Move core RDF files from lib/Target/Hexagon to CodeGen

[kparzysz]

Summary

The RDF now supports regmasks, which was the major missing feature preventing it from being used on other targets besides Hexagon.

[More tests have been done since the first patch was posted. See below for more details.]
This move includes the data-flow graph construction and recalculation of block live-ins. I have tested 3 targets: ARM, PowerPC and X86 using this scaffold, usually placed in post-RA pseudo-instruction expansion:

1. Construct the DFG.
2. Recalculate the block live-ins using the DFG.
3. Replace the existing live-ins with the calculated ones.
4. Carry on with the rest of the pass.

Then I checked each target via make check-llvm-codegen-<target>.

All tests on ARM and PowerPC pass, the X86 backend has 14 failures. At the first glance, about half of them are caused by the issue with EAX and AX having the same set of register units (in general E_X and _X). The remaining half seems to be caused by (as of yet) undetermined issues related to exception handling on Windows.

This patch does not introduce any functional changes, the only changes are in the locations of the files. Putting the files in CodeGen will make it easier to further test it and enable any potentially interested users to try it out.

New round of tests:

Implemented a target-independent RDF-optimization pass similar to Hexagon's RDF optimizations, i.e.:

• copy propagation
• dead code elimination
• liveness recomputation

Not surprisingly, many tests failed in "make check-llvm-codegen". I have manually checked the differences for AArch64, ARM and PowerPC, and the final code appeared to be correct, and the differences seemed to have been caused by the optimizations taking effect.

These tests also involved RDFCopy.cpp and RDFDeadCode.cpp, but these files are not included in this patch (for no other reason than that they were not included in the original patch).

[MatzeB]

My intuition would be that needing/computing a full dataflow graph that late in the compilation process is a bad sign. Having said that this probably won't go away for Hexagon and sharing code between targets is a good idea. Do you know of any plans to use this in other targets?

Some random nitpicks following but I didn't really read the whole patch yet.

include/llvm/CodeGen/RDFGraph.h

11

should be /// \file

279

I usually declare bitsets like this:

enum MyBitSet {
   A = 1u << 0,
   B = 1u << 1,
   C = 1u << 2,
   // ...
   // or 1u << FirstBit, 1u << FirstBit+1, if you cannot start at 1
   Mask = 0xf // Though I usually avoid masks and rather try to pack stuff into separate bitfield
              // members instead of putting them all in a uint16_t
};

which makes it more obvious what is happening.

361

Use doxygen comments.

lib/CodeGen/RDFLiveness.cpp

20

There is an alternative algorithm floating around, for example https://reviews.llvm.org/D28934

Which I usually prefer because it is simpler and doesn't require dominance tree construction. But I may be biased here :)

[hfinkel]

In D29295#660902, @MatzeB wrote:

My intuition would be that needing/computing a full dataflow graph that late in the compilation process is a bad sign. Having said that this probably won't go away for Hexagon and sharing code between targets is a good idea. Do you know of any plans to use this in other targets?

I'm certainly interested in testing this for PowerPC, and I'm happy to see this as target independent code. There are certainly cases where we want to do transformations post-RA where this kind of information is helpful (e.g. where we do register scavenging, shrink wrapping, etc.), and I'm definitely open to the possibility that this is the right way to get it.

We should definitely address the question of "Why is this needed currently?". If you're using this for copy propagation and DCE, why do you have dead code post-RA that was not eliminated by our pre-RA DCE? Why do you have copy-propagation opportunities that present themselves only after RA? Does this mean that you/we're missing opportunities to make better RA decisions?

Some random nitpicks following but I didn't really read the whole patch yet.

[kparzysz]

In D29295#661310, @hfinkel wrote:

We should definitely address the question of "Why is this needed currently?". If you're using this for copy propagation and DCE, why do you have dead code post-RA that was not eliminated by our pre-RA DCE? Why do you have copy-propagation opportunities that present themselves only after RA? Does this mean that you/we're missing opportunities to make better RA decisions?

CP/DCE was part of the original motivation for this effort. The idea of doing some post-RA optimizations had been floating around for quite some time before this code was written. Then after it was written, it took some time before it was upstreamed. Back then, the code coming out of the register allocator was not great---there were quite a few cases of register copies left over after PHI elimination, which we thought could be removed. We were receiving bug reports from our customers about redundant register assignments (crossing basic block boundary), etc., and we thought that having a general framework would help solve that, as well as provide a way to address any future concerns related to register allocation specifics.[1] Eventually, the register allocator became a lot better, and so that issue was no longer the most important. The CP/DCE code uses target-specific hooks, which on Hexagon, allow us to do some cleanup in cases that the register allocator cannot handle. For example, we can convert a post-increment load into a regular load where the address register is not used afterwards (i.e. the "increment" part of the instruction is "dead"). We could also recognize certain Hexagon instructions as copies, for example "r1:0 = combine(r2, r3)", which is equivalent to "r1 = r2; r0 = r3". In a more specific case, like "r1:0 = combine(r1, r3)", it could be replaced with "r0 = r3".[2] Those are not sources of major improvements in code size of performance, but still do some useful things that help certain benchmarks. Another role that they play at the moment is helping to test developments in the graph construction and liveness computations.

One of existing use cases for CP are situations where a register copy is immediately followed by uses of the destination register. This creates a flow dependency and restricts packetization. Even in the absence of DCE, CP itself could make a difference. The note [2] also refers to such cases. I don't have a testcase handy that shows this, but it still does happen in our code.

[1] Not all such issues are correctible in the allocator itself, as not all of them qualify as "bugs". For example, having a pair of copies "r1 = r10; r2 = r18" takes two instructions, but a pair "r1 = r10; r0 = r18" could be replaced with a single instruction "r1:0 = combine(r10, r18)". This form of register renaming is not implemented yet, but it would be a good use case for this framework. So far most of the time has been spent on developing the framework itself, and not so much on actually utilizing it (although we do have other users than the CP/DCE).

[2] Other things unchanged, this wouldn't make much of a difference. The benefit of doing it is to relax restrictions on post-RA scheduling (which on Hexagon includes packetization).

[kparzysz]

Converted comments with descriptions to doxygen format.

[kparzysz]

lib/CodeGen/RDFLiveness.cpp

20

The algorithm you linked to is for building/updating SSA, this one is for calculating block live-ins from existing SSA.

[hiraditya]

lib/CodeGen/RDFGraph.cpp

597

This function findBlock appears to be O(n) algorithm, and it is used in multiple places where this function is called for each BasicBlock in the function. Is there a way to speed up this algorithm.

[kparzysz]

lib/CodeGen/RDFGraph.cpp

597

The DFG has a private cache where it stores the addresses for quick lookup and it uses its own function to locate block nodes.

This function is restricted to use the public interfaces available from its class hierarchy and from the DFG, so it has to search all blocks. The search itself could be improved a bit, but it would remain O(n), and the code would become more complex.

[kparzysz]

Multiple fixes to RDF, addressed comments.

Increased the scope of testing: created an extra post-RA pass that ran the RDF-based copy propagation and dead code elimination, followed by liveness recomputation (in a similar way to what HexagonRDFOpt.cpp does). I manually checked "make check-llvm-codegen" failures on AArch64, ARM and PowerPC, and they seem to be caused by these optimizations modifying the code to a form not expected by the testcase. In all those cases the code appeared to still be correct.

[MatzeB]

This is a huge chunk of code to review, and to really form an opinion about it I believe it needs to be used in practice.
Overal the code looks fine to me, but I didn't dive in too deeply. I wonder if inventing a new allocator was really necessary here or what the point of TargetOperandInfo is (I would expect the register and regmask operand to have a specific clear meaning and this looks like a way to have targets override that?).

But all in all I'll leave review to whoever plans to use this code.

include/llvm/CodeGen/RDFGraph.h

11

seems unchanged.

926–941

You could use the Printable helper class here.

include/llvm/CodeGen/RDFLiveness.h

23–28

no indentation for namespaces, also a strange de-dent when the rdf namespace starts. Similar in the other files.

lib/CodeGen/RDFLiveness.cpp

20

Sorry, indeed.

[arsenm]

I've briefly looked at this before to use in AMDGPU, but was never entirely sure if this would actually help with my problems.

[arsenm]

Is there any progress on this? Can you post a rebased version?

[kparzysz]

Replaced by a recent D75932.

include/llvm/CodeGen/RDFGraph.h

+//===--- RDFGraph.h ---------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Target-independent, SSA-based data flow graph for register data flow (RDF)
+// for a non-SSA program representation (e.g. post-RA machine code).
+//
+//
+// *** Introduction
+//
+// The RDF graph is a collection of nodes, each of which denotes some element
+// of the program. There are two main types of such elements: code and refe-
+// rences. Conceptually, "code" is something that represents the structure
+// of the program, e.g. basic block or a statement, while "reference" is an
+// instance of accessing a register, e.g. a definition or a use. Nodes are
+// connected with each other based on the structure of the program (such as
+// blocks, instructions, etc.), and based on the data flow (e.g. reaching
+// definitions, reached uses, etc.). The single-reaching-definition principle
+// of SSA is generally observed, although, due to the non-SSA representation
+// of the program, there are some differences between the graph and a "pure"
+// SSA representation.
+//
+//
+// *** Implementation remarks
+//
+// Since the graph can contain a large number of nodes, memory consumption
+// was one of the major design considerations. As a result, there is a single
+// base class NodeBase which defines all members used by all possible derived
+// classes. The members are arranged in a union, and a derived class cannot
+// add any data members of its own. Each derived class only defines the
+// functional interface, i.e. member functions. NodeBase must be a POD,
+// which implies that all of its members must also be PODs.
+// Since nodes need to be connected with other nodes, pointers have been
+// replaced with 32-bit identifiers: each node has an id of type NodeId.
+// There are mapping functions in the graph that translate between actual
+// memory addresses and the corresponding identifiers.
+// A node id of 0 is equivalent to nullptr.
+//
+//
+// *** Structure of the graph
+//
+// A code node is always a collection of other nodes. For example, a code
+// node corresponding to a basic block will contain code nodes corresponding
+// to instructions. In turn, a code node corresponding to an instruction will
+// contain a list of reference nodes that correspond to the definitions and
+// uses of registers in that instruction. The members are arranged into a
+// circular list, which is yet another consequence of the effort to save
+// memory: for each member node it should be possible to obtain its owner,
+// and it should be possible to access all other members. There are other
+// ways to accomplish that, but the circular list seemed the most natural.
+//
+// +- CodeNode -+
+// |            | <---------------------------------------------------+
+// +-+--------+-+                                                     |
+//   |FirstM  |LastM                                                  |
+//   |        +-------------------------------------+                 |
+//   |                                              |                 |
+//   V                                              V                 |
+//  +----------+ Next +----------+ Next       Next +----------+ Next  |
+//  |          |----->|          |-----> ... ----->|          |----->-+
+//  +- Member -+      +- Member -+                 +- Member -+
+//
+// The order of members is such that related reference nodes (see below)
+// should be contiguous on the member list.
+//
+// A reference node is a node that encapsulates an access to a register,
+// in other words, data flowing into or out of a register. There are two
+// major kinds of reference nodes: defs and uses. A def node will contain
+// the id of the first reached use, and the id of the first reached def.
+// Each def and use will contain the id of the reaching def, and also the
+// id of the next reached def (for def nodes) or use (for use nodes).
+// The "next node sharing the same reaching def" is denoted as "sibling".
+// In summary:
+// - Def node contains: reaching def, sibling, first reached def, and first
+// reached use.
+// - Use node contains: reaching def and sibling.
+//
+// +-- DefNode --+
+// | R2 = ...    | <---+--------------------+
+// ++---------+--+     |                    |
+//  |Reached  |Reached |                    |
+//  |Def      |Use     |                    |
+//  |         |        |Reaching            |Reaching
+//  |         V        |Def                 |Def
+//  |      +-- UseNode --+ Sib  +-- UseNode --+ Sib       Sib
+//  |      | ... = R2    |----->| ... = R2    |----> ... ----> 0
+//  |      +-------------+      +-------------+
+//  V
+// +-- DefNode --+ Sib
+// | R2 = ...    |----> ...
+// ++---------+--+
+//  |         |
+//  |         |
+// ...       ...
+//
+// To get a full picture, the circular lists connecting blocks within a
+// function, instructions within a block, etc. should be superimposed with
+// the def-def, def-use links shown above.
+// To illustrate this, consider a small example in a pseudo-assembly:
+// foo:
+//   add r2, r0, r1   ; r2 = r0+r1
+//   addi r0, r2, 1   ; r0 = r2+1
+//   ret r0           ; return value in r0
+//
+// The graph (in a format used by the debugging functions) would look like:
+//
+//   DFG dump:[
+//   f1: Function foo
+//   b2: === BB#0 === preds(0), succs(0):
+//   p3: phi [d4<r0>(,d12,u9):]
+//   p5: phi [d6<r1>(,,u10):]
+//   s7: add [d8<r2>(,,u13):, u9<r0>(d4):, u10<r1>(d6):]
+//   s11: addi [d12<r0>(d4,,u15):, u13<r2>(d8):]
+//   s14: ret [u15<r0>(d12):]
+//   ]
+//
+// The f1, b2, p3, etc. are node ids. The letter is prepended to indicate the
+// kind of the node (i.e. f - function, b - basic block, p - phi, s - state-
+// ment, d - def, u - use).
+// The format of a def node is:
+//   dN<R>(rd,d,u):sib,
+// where
+//   N   - numeric node id,
+//   R   - register being defined
+//   rd  - reaching def,
+//   d   - reached def,
+//   u   - reached use,
+//   sib - sibling.
+// The format of a use node is:
+//   uN<R>[!](rd):sib,
+// where
+//   N   - numeric node id,
+//   R   - register being used,
+//   rd  - reaching def,
+//   sib - sibling.
+// Possible annotations (usually preceding the node id):
+//   +   - preserving def,
+//   ~   - clobbering def,
+//   "   - shadow ref (follows the node id),
+//   !   - fixed register (appears after register name).
+//
+// The circular lists are not explicit in the dump.
+//
+//
+// *** Node attributes
+//
+// NodeBase has a member "Attrs", which is the primary way of determining
+// the node's characteristics. The fields in this member decide whether
+// the node is a code node or a reference node (i.e. node's "type"), then
+// within each type, the "kind" determines what specifically this node
+// represents. The remaining bits, "flags", contain additional information
+// that is even more detailed than the "kind".
+// CodeNode's kinds are:
+// - Phi:   Phi node, members are reference nodes.
+// - Stmt:  Statement, members are reference nodes.
+// - Block: Basic block, members are instruction nodes (i.e. Phi or Stmt).
+// - Func:  The whole function. The members are basic block nodes.
+// RefNode's kinds are:
+// - Use.
+// - Def.
+//
+// Meaning of flags:
+// - Preserving: applies only to defs. A preserving def is one that can
+//   preserve some of the original bits among those that are included in
+//   the register associated with that def. For example, if R0 is a 32-bit
+//   register, but a def can only change the lower 16 bits, then it will
+//   be marked as preserving.
+// - Shadow: a reference that has duplicates holding additional reaching
+//   defs (see more below).
+// - Clobbering: applied only to defs, indicates that the value generated
+//   by this def is unspecified. A typical example would be volatile registers
+//   after function calls.
+// - Fixed: the register in this def/use cannot be replaced with any other
+//   register. A typical case would be a parameter register to a call, or
+//   the register with the return value from a function.
+// - Undef: the register in this reference the register is assumed to have
+//   no pre-existing value, even if it appears to be reached by some def.
+//   This is typically used to prevent keeping registers artificially live
+//   in cases when they are defined via predicated instructions. For example:
+//     r0 = add-if-true cond, r10, r11                (1)
+//     r0 = add-if-false cond, r12, r13, r0<imp-use>  (2)
+//     ... = r0                                       (3)
+//   Before (1), r0 is not intended to be live, and the use of r0 in (3) is
+//   not meant to be reached by any def preceding (1). However, since the
+//   defs in (1) and (2) are both preserving, these properties alone would
+//   imply that the use in (3) may indeed be reached by some prior def.
+//   Adding Undef flag to the def in (1) prevents that. The Undef flag
+//   may be applied to both defs and uses.
+// - Dead: applies only to defs. The value coming out of a "dead" def is
+//   assumed to be unused, even if the def appears to be reaching other defs
+//   or uses. The motivation for this flag comes from dead defs on function
+//   calls: there is no way to determine if such a def is dead without
+//   analyzing the target's ABI. Hence the graph should contain this info,
+//   as it is unavailable otherwise. On the other hand, a def without any
+//   uses on a typical instruction is not the intended target for this flag.
+//
+// *** Shadow references
+//
+// It may happen that a super-register can have two (or more) non-overlapping
+// sub-registers. When both of these sub-registers are defined and followed
+// by a use of the super-register, the use of the super-register will not
+// have a unique reaching def: both defs of the sub-registers need to be
+// accounted for. In such cases, a duplicate use of the super-register is
+// added and it points to the extra reaching def. Both uses are marked with
+// a flag "shadow". Example:
+// Assume t0 is a super-register of r0 and r1, r0 and r1 do not overlap:
+//   set r0, 1        ; r0 = 1
+//   set r1, 1        ; r1 = 1
+//   addi t1, t0, 1   ; t1 = t0+1
+//
+// The DFG:
+//   s1: set [d2<r0>(,,u9):]
+//   s3: set [d4<r1>(,,u10):]
+//   s5: addi [d6<t1>(,,):, u7"<t0>(d2):, u8"<t0>(d4):]
+//
+// The statement s5 has two use nodes for t0: u7" and u9". The quotation
+// mark " indicates that the node is a shadow.
+//
+
+#ifndef LLVM_CODEGEN_RDFGRAPH_H
+#define LLVM_CODEGEN_RDFGRAPH_H
+
+#include "llvm/ADT/BitVector.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/CodeGen/RDFRegisters.h"
+#include "llvm/MC/LaneBitmask.h"
+#include "llvm/Support/Allocator.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include <cassert>
+#include <cstdint>
+#include <cstring>
+#include <functional>
+#include <map>
+#include <set>
+#include <unordered_map>
+#include <utility>
+#include <vector>
+
+// RDF uses uint32_t to refer to registers. This is to ensure that the type
+// size remains specific. In other places, registers are often stored using
+// unsigned.
+static_assert(sizeof(uint32_t) == sizeof(unsigned), "Those should be equal");
+
+namespace llvm {
+
+  class MachineBasicBlock;
+  class MachineFunction;
+  class MachineInstr;
+  class MachineOperand;
+  class MachineDominanceFrontier;
+  class MachineDominatorTree;
+  class TargetInstrInfo;
+
+namespace rdf {
+
+  typedef uint32_t NodeId;
+
+  struct DataFlowGraph;
+
+  struct NodeAttrs {
+    enum : uint16_t {
+      None          = 0x0000,   // Nothing
+
+      // Types: 2 bits
+      TypeMask      = 0x0003,
+      Code          = 0x0001,   // 01, Container
+      Ref           = 0x0002,   // 10, Reference
+
+      // Kind: 3 bits
+      KindMask      = 0x0007 << 2,
+      Def           = 0x0001 << 2,  // 001
+      Use           = 0x0002 << 2,  // 010
+      Phi           = 0x0003 << 2,  // 011
+      Stmt          = 0x0004 << 2,  // 100
+      Block         = 0x0005 << 2,  // 101
+      Func          = 0x0006 << 2,  // 110
+
+      // Flags: 7 bits for now
+      FlagMask      = 0x007F << 5,
+      Shadow        = 0x0001 << 5,  // 0000001, Has extra reaching defs.
+      Clobbering    = 0x0002 << 5,  // 0000010, Produces unspecified values.
+      PhiRef        = 0x0004 << 5,  // 0000100, Member of PhiNode.
+      Preserving    = 0x0008 << 5,  // 0001000, Def can keep original bits.
+      Fixed         = 0x0010 << 5,  // 0010000, Fixed register.
+      Undef         = 0x0020 << 5,  // 0100000, Has no pre-existing value.
+      Dead          = 0x0040 << 5,  // 1000000, Does not define a value.
+    };
+
+    static uint16_t type(uint16_t T)  { return T & TypeMask; }
+    static uint16_t kind(uint16_t T)  { return T & KindMask; }
+    static uint16_t flags(uint16_t T) { return T & FlagMask; }
+
+    static uint16_t set_type(uint16_t A, uint16_t T) {
+      return (A & ~TypeMask) | T;
+    }
+
+    static uint16_t set_kind(uint16_t A, uint16_t K) {
+      return (A & ~KindMask) | K;
+    }
+
+    static uint16_t set_flags(uint16_t A, uint16_t F) {
+      return (A & ~FlagMask) | F;
+    }
+
+    // Test if A contains B.
+    static bool contains(uint16_t A, uint16_t B) {
+      if (type(A) != Code)
+        return false;
+      uint16_t KB = kind(B);
+      switch (kind(A)) {
+        case Func:
+          return KB == Block;
+        case Block:
+          return KB == Phi || KB == Stmt;
+        case Phi:
+        case Stmt:
+          return type(B) == Ref;
+      }
+      return false;
+    }
+  };
+
+  struct BuildOptions {
+    enum : unsigned {
+      None          = 0x00,
+      KeepDeadPhis  = 0x01,   // Do not remove dead phis during build.
+    };
+  };
+
+  template <typename T> struct NodeAddr {
+    NodeAddr() : Addr(nullptr) {}
+    NodeAddr(T A, NodeId I) : Addr(A), Id(I) {}
+
+    // Type cast (casting constructor). The reason for having this class
+    // instead of std::pair.
+    template <typename S> NodeAddr(const NodeAddr<S> &NA)
+      : Addr(static_cast<T>(NA.Addr)), Id(NA.Id) {}
+
+    bool operator== (const NodeAddr<T> &NA) const {
+      assert((Addr == NA.Addr) == (Id == NA.Id));
+      return Addr == NA.Addr;
+    }
+    bool operator!= (const NodeAddr<T> &NA) const {
+      return !operator==(NA);
+    }
+
+    T Addr;
+    NodeId Id = 0;
+  };
+
+  struct NodeBase;
+
+  // Fast memory allocation and translation between node id and node address.
+  // This is really the same idea as the one underlying the "bump pointer
+  // allocator", the difference being in the translation. A node id is
+  // composed of two components: the index of the block in which it was
+  // allocated, and the index within the block. With the default settings,
+  // where the number of nodes per block is 4096, the node id (minus 1) is:
+  //
+  // bit position:                11             0
+  // +----------------------------+--------------+
+  // | Index of the block         |Index in block|
+  // +----------------------------+--------------+
+  //
+  // The actual node id is the above plus 1, to avoid creating a node id of 0.
+  //
+  // This method significantly improved the build time, compared to using maps
+  // (std::unordered_map or DenseMap) to translate between pointers and ids.
+  struct NodeAllocator {
+    // Amount of storage for a single node.
+    enum { NodeMemSize = 32 };
+
+    NodeAllocator(uint32_t NPB = 4096)
+        : NodesPerBlock(NPB), BitsPerIndex(Log2_32(NPB)),
+          IndexMask((1 << BitsPerIndex)-1) {
+      assert(isPowerOf2_32(NPB));
+    }
+
+    NodeBase *ptr(NodeId N) const {
+      uint32_t N1 = N-1;
+      uint32_t BlockN = N1 >> BitsPerIndex;
+      uint32_t Offset = (N1 & IndexMask) * NodeMemSize;
+      return reinterpret_cast<NodeBase*>(Blocks[BlockN]+Offset);
+    }
+
+    NodeId id(const NodeBase *P) const;
+    NodeAddr<NodeBase*> New();
+    void clear();
+
+  private:
+    void startNewBlock();
+    bool needNewBlock();
+
+    uint32_t makeId(uint32_t Block, uint32_t Index) const {
+      // Add 1 to the id, to avoid the id of 0, which is treated as "null".
+      return ((Block << BitsPerIndex) | Index) + 1;
+    }
+
+    const uint32_t NodesPerBlock;
+    const uint32_t BitsPerIndex;
+    const uint32_t IndexMask;
+    char *ActiveEnd = nullptr;
+    std::vector<char*> Blocks;
+    typedef BumpPtrAllocatorImpl<MallocAllocator, 65536> AllocatorTy;
+    AllocatorTy MemPool;
+  };
+
+  typedef std::set<RegisterRef> RegisterSet;
+
+  struct TargetOperandInfo {
+    TargetOperandInfo(const TargetInstrInfo &tii) : TII(tii) {}
+    virtual ~TargetOperandInfo() = default;
+
+    virtual bool isPreserving(const MachineInstr &In, unsigned OpNum) const;
+    virtual bool isClobbering(const MachineInstr &In, unsigned OpNum) const;
+    virtual bool isFixedReg(const MachineInstr &In, unsigned OpNum) const;
+
+    const TargetInstrInfo &TII;
+  };
+
+  // Packed register reference. Only used for storage.
+  struct PackedRegisterRef {
+    RegisterId Reg;
+    uint32_t MaskId;
+  };
+
+  struct LaneMaskIndex : private IndexedSet<LaneBitmask> {
+    LaneMaskIndex() = default;
+
+    LaneBitmask getLaneMaskForIndex(uint32_t K) const {
+      return K == 0 ? LaneBitmask::getAll() : get(K);
+    }
+    uint32_t getIndexForLaneMask(LaneBitmask LM) {
+      assert(LM.any());
+      return LM.all() ? 0 : insert(LM);
+    }
+    uint32_t getIndexForLaneMask(LaneBitmask LM) const {
+      assert(LM.any());
+      return LM.all() ? 0 : find(LM);
+    }
+  };
+
+  struct NodeBase {
+  public:
+    // Make sure this is a POD.
+    NodeBase() = default;
+
+    uint16_t getType()  const { return NodeAttrs::type(Attrs); }
+    uint16_t getKind()  const { return NodeAttrs::kind(Attrs); }
+    uint16_t getFlags() const { return NodeAttrs::flags(Attrs); }
+    NodeId   getNext()  const { return Next; }
+
+    uint16_t getAttrs() const { return Attrs; }
+    void setAttrs(uint16_t A) { Attrs = A; }
+    void setFlags(uint16_t F) { setAttrs(NodeAttrs::set_flags(getAttrs(), F)); }
+
+    // Insert node NA after "this" in the circular chain.
+    void append(NodeAddr<NodeBase*> NA);
+    // Initialize all members to 0.
+    void init() { memset(this, 0, sizeof *this); }
+    void setNext(NodeId N) { Next = N; }
+
+  protected:
+    uint16_t Attrs;
+    uint16_t Reserved;
+    NodeId Next;                // Id of the next node in the circular chain.
+    // Definitions of nested types. Using anonymous nested structs would make
+    // this class definition clearer, but unnamed structs are not a part of
+    // the standard.
+    struct Def_struct  {
+      NodeId DD, DU;          // Ids of the first reached def and use.
+    };
+    struct PhiU_struct  {
+      NodeId PredB;           // Id of the predecessor block for a phi use.
+    };
+    struct Code_struct {
+      void *CP;               // Pointer to the actual code.
+      NodeId FirstM, LastM;   // Id of the first member and last.
+    };
+    struct Ref_struct {
+      NodeId RD, Sib;         // Ids of the reaching def and the sibling.
+      union {
+        Def_struct Def;
+        PhiU_struct PhiU;
+      };
+      union {
+        MachineOperand *Op;   // Non-phi refs point to a machine operand.
+        PackedRegisterRef PR; // Phi refs store register info directly.
+      };
+    };
+
+    // The actual payload.
+    union {
+      Ref_struct Ref;
+      Code_struct Code;
+    };
+  };
+  // The allocator allocates chunks of 32 bytes for each node. The fact that
+  // each node takes 32 bytes in memory is used for fast translation between
+  // the node id and the node address.
+  static_assert(sizeof(NodeBase) <= NodeAllocator::NodeMemSize,
+        "NodeBase must be at most NodeAllocator::NodeMemSize bytes");
+
+  typedef std::vector<NodeAddr<NodeBase*>> NodeList;
+  typedef std::set<NodeId> NodeSet;
+
+  struct RefNode : public NodeBase {
+    RefNode() = default;
+
+    RegisterRef getRegRef(const DataFlowGraph &G) const;
+
+    MachineOperand &getOp() {
+      assert(!(getFlags() & NodeAttrs::PhiRef));
+      return *Ref.Op;
+    }
+
+    void setRegRef(RegisterRef RR, DataFlowGraph &G);
+    void setRegRef(MachineOperand *Op, DataFlowGraph &G);
+
+    NodeId getReachingDef() const {
+      return Ref.RD;
+    }
+    void setReachingDef(NodeId RD) {
+      Ref.RD = RD;
+    }
+
+    NodeId getSibling() const {
+      return Ref.Sib;
+    }
+    void setSibling(NodeId Sib) {
+      Ref.Sib = Sib;
+    }
+
+    bool isUse() const {
+      assert(getType() == NodeAttrs::Ref);
+      return getKind() == NodeAttrs::Use;
+    }
+
+    bool isDef() const {
+      assert(getType() == NodeAttrs::Ref);
+      return getKind() == NodeAttrs::Def;
+    }
+
+    template <typename Predicate>
+    NodeAddr<RefNode*> getNextRef(RegisterRef RR, Predicate P, bool NextOnly,
+        const DataFlowGraph &G);
+    NodeAddr<NodeBase*> getOwner(const DataFlowGraph &G);
+  };
+
+  struct DefNode : public RefNode {
+    NodeId getReachedDef() const {
+      return Ref.Def.DD;
+    }
+    void setReachedDef(NodeId D) {
+      Ref.Def.DD = D;
+    }
+    NodeId getReachedUse() const {
+      return Ref.Def.DU;
+    }
+    void setReachedUse(NodeId U) {
+      Ref.Def.DU = U;
+    }
+
+    void linkToDef(NodeId Self, NodeAddr<DefNode*> DA);
+  };
+
+  struct UseNode : public RefNode {
+    void linkToDef(NodeId Self, NodeAddr<DefNode*> DA);
+  };
+
+  struct PhiUseNode : public UseNode {
+    NodeId getPredecessor() const {
+      assert(getFlags() & NodeAttrs::PhiRef);
+      return Ref.PhiU.PredB;
+    }
+    void setPredecessor(NodeId B) {
+      assert(getFlags() & NodeAttrs::PhiRef);
+      Ref.PhiU.PredB = B;
+    }
+  };
+
+  struct CodeNode : public NodeBase {
+    template <typename T> T getCode() const {
+      return static_cast<T>(Code.CP);
+    }
+    void setCode(void *C) {
+      Code.CP = C;
+    }
+
+    NodeAddr<NodeBase*> getFirstMember(const DataFlowGraph &G) const;
+    NodeAddr<NodeBase*> getLastMember(const DataFlowGraph &G) const;
+    void addMember(NodeAddr<NodeBase*> NA, const DataFlowGraph &G);
+    void addMemberAfter(NodeAddr<NodeBase*> MA, NodeAddr<NodeBase*> NA,
+        const DataFlowGraph &G);
+    void removeMember(NodeAddr<NodeBase*> NA, const DataFlowGraph &G);
+
+    NodeList members(const DataFlowGraph &G) const;
+    template <typename Predicate>
+    NodeList members_if(Predicate P, const DataFlowGraph &G) const;
+  };
+
+  struct InstrNode : public CodeNode {
+    NodeAddr<NodeBase*> getOwner(const DataFlowGraph &G);
+  };
+
+  struct PhiNode : public InstrNode {
+    MachineInstr *getCode() const {
+      return nullptr;
+    }
+  };
+
+  struct StmtNode : public InstrNode {
+    MachineInstr *getCode() const {
+      return CodeNode::getCode<MachineInstr*>();
+    }
+  };
+
+  struct BlockNode : public CodeNode {
+    MachineBasicBlock *getCode() const {
+      return CodeNode::getCode<MachineBasicBlock*>();
+    }
+
+    void addPhi(NodeAddr<PhiNode*> PA, const DataFlowGraph &G);
+  };
+
+  struct FuncNode : public CodeNode {
+    MachineFunction *getCode() const {
+      return CodeNode::getCode<MachineFunction*>();
+    }
+
+    NodeAddr<BlockNode*> findBlock(const MachineBasicBlock *BB,
+        const DataFlowGraph &G) const;
+    NodeAddr<BlockNode*> getEntryBlock(const DataFlowGraph &G);
+  };
+
+  struct DataFlowGraph {
+    DataFlowGraph(MachineFunction &mf, const TargetInstrInfo &tii,
+        const TargetRegisterInfo &tri, const MachineDominatorTree &mdt,
+        const MachineDominanceFrontier &mdf, const TargetOperandInfo &toi);
+
+    NodeBase *ptr(NodeId N) const;
+    template <typename T> T ptr(NodeId N) const {
+      return static_cast<T>(ptr(N));
+    }
+
+    NodeId id(const NodeBase *P) const;
+
+    template <typename T> NodeAddr<T> addr(NodeId N) const {
+      return { ptr<T>(N), N };
+    }
+
+    NodeAddr<FuncNode*> getFunc() const { return Func; }
+    MachineFunction &getMF() const { return MF; }
+    const TargetInstrInfo &getTII() const { return TII; }
+    const TargetRegisterInfo &getTRI() const { return TRI; }
+    const PhysicalRegisterInfo &getPRI() const { return PRI; }
+    const MachineDominatorTree &getDT() const { return MDT; }
+    const MachineDominanceFrontier &getDF() const { return MDF; }
+    const RegisterAggr &getLiveIns() const { return LiveIns; }
+
+    struct DefStack {
+      DefStack() = default;
+
+      bool empty() const { return Stack.empty() || top() == bottom(); }
+
+    private:
+      typedef NodeAddr<DefNode*> value_type;
+      struct Iterator {
+        typedef DefStack::value_type value_type;
+
+        Iterator &up() { Pos = DS.nextUp(Pos); return *this; }
+        Iterator &down() { Pos = DS.nextDown(Pos); return *this; }
+
+        value_type operator*() const {
+          assert(Pos >= 1);
+          return DS.Stack[Pos-1];
+        }
+        const value_type *operator->() const {
+          assert(Pos >= 1);
+          return &DS.Stack[Pos-1];
+        }
+        bool operator==(const Iterator &It) const { return Pos == It.Pos; }
+        bool operator!=(const Iterator &It) const { return Pos != It.Pos; }
+
+      private:
+        Iterator(const DefStack &S, bool Top);
+
+        // Pos-1 is the index in the StorageType object that corresponds to
+        // the top of the DefStack.
+        const DefStack &DS;
+        unsigned Pos;
+        friend struct DefStack;
+      };
+
+    public:
+      typedef Iterator iterator;
+      iterator top() const { return Iterator(*this, true); }
+      iterator bottom() const { return Iterator(*this, false); }
+      unsigned size() const;
+
+      void push(NodeAddr<DefNode*> DA) { Stack.push_back(DA); }
+      void pop();
+      void start_block(NodeId N);
+      void clear_block(NodeId N);
+
+    private:
+      friend struct Iterator;
+      typedef std::vector<value_type> StorageType;
+
+      bool isDelimiter(const StorageType::value_type &P, NodeId N = 0) const {
+        return (P.Addr == nullptr) && (N == 0 || P.Id == N);
+      }
+
+      unsigned nextUp(unsigned P) const;
+      unsigned nextDown(unsigned P) const;
+
+      StorageType Stack;
+    };
+
+    // Make this std::unordered_map for speed of accessing elements.
+    // Map: Register (physical or virtual) -> DefStack
+    typedef std::unordered_map<RegisterId,DefStack> DefStackMap;
+
+    void build(unsigned Options = BuildOptions::None);
+    void pushAllDefs(NodeAddr<InstrNode*> IA, DefStackMap &DM);
+    void markBlock(NodeId B, DefStackMap &DefM);
+    void releaseBlock(NodeId B, DefStackMap &DefM);
+
+    PackedRegisterRef pack(RegisterRef RR) {
+      return { RR.Reg, LMI.getIndexForLaneMask(RR.Mask) };
+    }
+    PackedRegisterRef pack(RegisterRef RR) const {
+      return { RR.Reg, LMI.getIndexForLaneMask(RR.Mask) };
+    }
+    RegisterRef unpack(PackedRegisterRef PR) const {
+      return RegisterRef(PR.Reg, LMI.getLaneMaskForIndex(PR.MaskId));
+    }
+
+    RegisterRef makeRegRef(unsigned Reg, unsigned Sub) const;
+    RegisterRef makeRegRef(const MachineOperand &Op) const;
+    RegisterRef restrictRef(RegisterRef AR, RegisterRef BR) const;
+
+    NodeAddr<RefNode*> getNextRelated(NodeAddr<InstrNode*> IA,
+        NodeAddr<RefNode*> RA) const;
+    NodeAddr<RefNode*> getNextImp(NodeAddr<InstrNode*> IA,
+        NodeAddr<RefNode*> RA, bool Create);
+    NodeAddr<RefNode*> getNextImp(NodeAddr<InstrNode*> IA,
+        NodeAddr<RefNode*> RA) const;
+    NodeAddr<RefNode*> getNextShadow(NodeAddr<InstrNode*> IA,
+        NodeAddr<RefNode*> RA, bool Create);
+    NodeAddr<RefNode*> getNextShadow(NodeAddr<InstrNode*> IA,
+        NodeAddr<RefNode*> RA) const;
+
+    NodeList getRelatedRefs(NodeAddr<InstrNode*> IA,
+        NodeAddr<RefNode*> RA) const;
+
+    NodeAddr<BlockNode*> findBlock(MachineBasicBlock *BB) const {
+      return BlockNodes.at(BB);
+    }
+
+    void unlinkUse(NodeAddr<UseNode*> UA, bool RemoveFromOwner) {
+      unlinkUseDF(UA);
+      if (RemoveFromOwner)
+        removeFromOwner(UA);
+    }
+
+    void unlinkDef(NodeAddr<DefNode*> DA, bool RemoveFromOwner) {
+      unlinkDefDF(DA);
+      if (RemoveFromOwner)
+        removeFromOwner(DA);
+    }
+
+    // Some useful filters.
+    template <uint16_t Kind>
+    static bool IsRef(const NodeAddr<NodeBase*> BA) {
+      return BA.Addr->getType() == NodeAttrs::Ref &&
+             BA.Addr->getKind() == Kind;
+    }
+
+    template <uint16_t Kind>
+    static bool IsCode(const NodeAddr<NodeBase*> BA) {
+      return BA.Addr->getType() == NodeAttrs::Code &&
+             BA.Addr->getKind() == Kind;
+    }
+
+    static bool IsDef(const NodeAddr<NodeBase*> BA) {
+      return BA.Addr->getType() == NodeAttrs::Ref &&
+             BA.Addr->getKind() == NodeAttrs::Def;
+    }
+
+    static bool IsUse(const NodeAddr<NodeBase*> BA) {
+      return BA.Addr->getType() == NodeAttrs::Ref &&
+             BA.Addr->getKind() == NodeAttrs::Use;
+    }
+
+    static bool IsPhi(const NodeAddr<NodeBase*> BA) {
+      return BA.Addr->getType() == NodeAttrs::Code &&
+             BA.Addr->getKind() == NodeAttrs::Phi;
+    }
+
+    static bool IsPreservingDef(const NodeAddr<DefNode*> DA) {
+      uint16_t Flags = DA.Addr->getFlags();
+      return (Flags & NodeAttrs::Preserving) && !(Flags & NodeAttrs::Undef);
+    }
+
+  private:
+    void reset();
+
+    RegisterSet getLandingPadLiveIns() const;
+
+    NodeAddr<NodeBase*> newNode(uint16_t Attrs);
+    NodeAddr<NodeBase*> cloneNode(const NodeAddr<NodeBase*> B);
+    NodeAddr<UseNode*> newUse(NodeAddr<InstrNode*> Owner,
+        MachineOperand &Op, uint16_t Flags = NodeAttrs::None);
+    NodeAddr<PhiUseNode*> newPhiUse(NodeAddr<PhiNode*> Owner,
+        RegisterRef RR, NodeAddr<BlockNode*> PredB,
+        uint16_t Flags = NodeAttrs::PhiRef);
+    NodeAddr<DefNode*> newDef(NodeAddr<InstrNode*> Owner,
+        MachineOperand &Op, uint16_t Flags = NodeAttrs::None);
+    NodeAddr<DefNode*> newDef(NodeAddr<InstrNode*> Owner,
+        RegisterRef RR, uint16_t Flags = NodeAttrs::PhiRef);
+    NodeAddr<PhiNode*> newPhi(NodeAddr<BlockNode*> Owner);
+    NodeAddr<StmtNode*> newStmt(NodeAddr<BlockNode*> Owner,
+        MachineInstr *MI);
+    NodeAddr<BlockNode*> newBlock(NodeAddr<FuncNode*> Owner,
+        MachineBasicBlock *BB);
+    NodeAddr<FuncNode*> newFunc(MachineFunction *MF);
+
+    template <typename Predicate>
+    std::pair<NodeAddr<RefNode*>,NodeAddr<RefNode*>>
+    locateNextRef(NodeAddr<InstrNode*> IA, NodeAddr<RefNode*> RA,
+        Predicate P) const;
+
+    typedef std::map<NodeId,RegisterSet> BlockRefsMap;
+
+    void buildStmt(NodeAddr<BlockNode*> BA, MachineInstr &In);
+    void buildBlockRefs(NodeAddr<BlockNode*> BA, BlockRefsMap &RefM);
+    void recordDefsForDF(BlockRefsMap &PhiM, BlockRefsMap &RefM,
+        NodeAddr<BlockNode*> BA);
+    void buildPhis(BlockRefsMap &PhiM, BlockRefsMap &RefM,
+        NodeAddr<BlockNode*> BA);
+    void removeUnusedPhis();
+
+    void pushClobbers(NodeAddr<InstrNode*> IA, DefStackMap &DM);
+    void pushDefs(NodeAddr<InstrNode*> IA, DefStackMap &DM);
+    template <typename T> void linkRefUp(NodeAddr<InstrNode*> IA,
+        NodeAddr<T> TA, DefStack &DS);
+    template <typename Predicate> void linkStmtRefs(DefStackMap &DefM,
+        NodeAddr<StmtNode*> SA, Predicate P);
+    void linkBlockRefs(DefStackMap &DefM, NodeAddr<BlockNode*> BA);
+
+    void unlinkUseDF(NodeAddr<UseNode*> UA);
+    void unlinkDefDF(NodeAddr<DefNode*> DA);
+
+    void removeFromOwner(NodeAddr<RefNode*> RA) {
+      NodeAddr<InstrNode*> IA = RA.Addr->getOwner(*this);
+      IA.Addr->removeMember(RA, *this);
+    }
+
+    MachineFunction &MF;
+    const TargetInstrInfo &TII;
+    const TargetRegisterInfo &TRI;
+    const PhysicalRegisterInfo PRI;
+    const MachineDominatorTree &MDT;
+    const MachineDominanceFrontier &MDF;
+    const TargetOperandInfo &TOI;
+
+    RegisterAggr LiveIns;
+    NodeAddr<FuncNode*> Func;
+    NodeAllocator Memory;
+    // Local map:  MachineBasicBlock -> NodeAddr<BlockNode*>
+    std::map<MachineBasicBlock*,NodeAddr<BlockNode*>> BlockNodes;
+    // Lane mask map.
+    LaneMaskIndex LMI;
+  };  // struct DataFlowGraph
+
+  template <typename Predicate>
+  NodeAddr<RefNode*> RefNode::getNextRef(RegisterRef RR, Predicate P,
+        bool NextOnly, const DataFlowGraph &G) {
+    // Get the "Next" reference in the circular list that references RR and
+    // satisfies predicate "Pred".
+    auto NA = G.addr<NodeBase*>(getNext());
+
+    while (NA.Addr != this) {
+      if (NA.Addr->getType() == NodeAttrs::Ref) {
+        NodeAddr<RefNode*> RA = NA;
+        if (RA.Addr->getRegRef(G) == RR && P(NA))
+          return NA;
+        if (NextOnly)
+          break;
+        NA = G.addr<NodeBase*>(NA.Addr->getNext());
+      } else {
+        // We've hit the beginning of the chain.
+        assert(NA.Addr->getType() == NodeAttrs::Code);
+        NodeAddr<CodeNode*> CA = NA;
+        NA = CA.Addr->getFirstMember(G);
+      }
+    }
+    // Return the equivalent of "nullptr" if such a node was not found.
+    return NodeAddr<RefNode*>();
+  }
+
+  template <typename Predicate>
+  NodeList CodeNode::members_if(Predicate P, const DataFlowGraph &G) const {
+    NodeList MM;
+    auto M = getFirstMember(G);
+    if (M.Id == 0)
+      return MM;
+
+    while (M.Addr != this) {
+      if (P(M))
+        MM.push_back(M);
+      M = G.addr<NodeBase*>(M.Addr->getNext());
+    }
+    return MM;
+  }
+
+
+  template <typename T> struct Print;
+  template <typename T>
+  raw_ostream &operator<< (raw_ostream &OS, const Print<T> &P);
+
+  template <typename T>
+  struct Print {
+    Print(const T &x, const DataFlowGraph &g) : Obj(x), G(g) {}
+    const T &Obj;
+    const DataFlowGraph &G;
+  };
+
+  template <typename T>
+  struct PrintNode : Print<NodeAddr<T>> {
+    PrintNode(const NodeAddr<T> &x, const DataFlowGraph &g)
+      : Print<NodeAddr<T>>(x, g) {}
+  };
+
+} // end namespace rdf
+
+} // end namespace llvm
+
+#endif // LLVM_CODEGEN_RDFGRAPH_H

include/llvm/CodeGen/RDFLiveness.h

+//===--- RDFLiveness.h ----------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Recalculate the liveness information given a data flow graph.
+// This includes block live-ins and kill flags.
+
+#ifndef LLVM_CODEGEN_RDFLIVENESS_H
+#define LLVM_CODEGEN_RDFLIVENESS_H
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/CodeGen/RDFGraph.h"
+#include <map>
+
+using namespace llvm;
+
+namespace llvm {
+  class MachineBasicBlock;
+  class MachineFunction;
+  class MachineRegisterInfo;
+  class TargetRegisterInfo;
+  class MachineDominatorTree;
+  class MachineDominanceFrontier;
+
+namespace rdf {
+  struct Liveness {
+  public:
+    // This is really a std::map, except that it provides a non-trivial
+    // default constructor to the element accessed via [].
+    struct LiveMapType {
+      LiveMapType(const PhysicalRegisterInfo &pri) : Empty(pri) {}
+
+      RegisterAggr &operator[] (MachineBasicBlock *B) {
+        return Map.emplace(B, Empty).first->second;
+      }
+    private:
+      RegisterAggr Empty;
+      std::map<MachineBasicBlock*,RegisterAggr> Map;
+    };
+
+    typedef std::pair<NodeId,LaneBitmask> NodeRef;
+    typedef std::set<NodeRef> NodeRefSet;
+    // RegisterId in RefMap must be normalized.
+    typedef std::map<RegisterId,NodeRefSet> RefMap;
+
+    Liveness(MachineRegisterInfo &mri, const DataFlowGraph &g)
+      : DFG(g), TRI(g.getTRI()), PRI(g.getPRI()), MDT(g.getDT()),
+        MDF(g.getDF()), LiveMap(g.getPRI()), Empty(),
+        NoRegs(g.getPRI()), Trace(false) {}
+
+    NodeList getAllReachingDefs(RegisterRef RefRR, NodeAddr<RefNode*> RefA,
+        bool TopShadows, bool FullChain, const RegisterAggr &DefRRs);
+    NodeList getAllReachingDefs(NodeAddr<RefNode*> RefA) {
+      return getAllReachingDefs(RefA.Addr->getRegRef(DFG), RefA, false,
+                                false, NoRegs);
+    }
+    NodeList getAllReachingDefs(RegisterRef RefRR, NodeAddr<RefNode*> RefA) {
+      return getAllReachingDefs(RefRR, RefA, false, false, NoRegs);
+    }
+    NodeSet getAllReachedUses(RegisterRef RefRR, NodeAddr<DefNode*> DefA,
+        const RegisterAggr &DefRRs);
+    NodeSet getAllReachedUses(RegisterRef RefRR, NodeAddr<DefNode*> DefA) {
+      return getAllReachedUses(RefRR, DefA, NoRegs);
+    }
+
+    std::pair<NodeSet,bool> getAllReachingDefsRec(RegisterRef RefRR,
+        NodeAddr<RefNode*> RefA, NodeSet &Visited, const NodeSet &Defs);
+
+    NodeAddr<RefNode*> getNearestAliasedRef(RegisterRef RefRR,
+        NodeAddr<InstrNode*> IA);
+
+    LiveMapType &getLiveMap() { return LiveMap; }
+    const LiveMapType &getLiveMap() const { return LiveMap; }
+    const RefMap &getRealUses(NodeId P) const {
+      auto F = RealUseMap.find(P);
+      return F == RealUseMap.end() ? Empty : F->second;
+    }
+
+    void computePhiInfo();
+    void computeLiveIns();
+    void resetLiveIns();
+    void resetKills();
+    void resetKills(MachineBasicBlock *B);
+
+    void trace(bool T) { Trace = T; }
+
+  private:
+    const DataFlowGraph &DFG;
+    const TargetRegisterInfo &TRI;
+    const PhysicalRegisterInfo &PRI;
+    const MachineDominatorTree &MDT;
+    const MachineDominanceFrontier &MDF;
+    LiveMapType LiveMap;
+    const RefMap Empty;
+    const RegisterAggr NoRegs;
+    bool Trace;
+
+    // Cache of mapping from node ids (for RefNodes) to the containing
+    // basic blocks. Not computing it each time for each node reduces
+    // the liveness calculation time by a large fraction.
+    typedef DenseMap<NodeId,MachineBasicBlock*> NodeBlockMap;
+    NodeBlockMap NBMap;
+
+    // Phi information:
+    //
+    // RealUseMap
+    // map: NodeId -> (map: RegisterId -> NodeRefSet)
+    //      phi id -> (map: register -> set of reached non-phi uses)
+    std::map<NodeId, RefMap> RealUseMap;
+
+    // Inverse iterated dominance frontier.
+    std::map<MachineBasicBlock*,std::set<MachineBasicBlock*>> IIDF;
+
+    // Live on entry.
+    std::map<MachineBasicBlock*,RefMap> PhiLON;
+
+    // Phi uses are considered to be located at the end of the block that
+    // they are associated with. The reaching def of a phi use dominates the
+    // block that the use corresponds to, but not the block that contains
+    // the phi itself. To include these uses in the liveness propagation (up
+    // the dominator tree), create a map: block -> set of uses live on exit.
+    std::map<MachineBasicBlock*,RefMap> PhiLOX;
+
+    MachineBasicBlock *getBlockWithRef(NodeId RN) const;
+    void traverse(MachineBasicBlock *B, RefMap &LiveIn);
+    void emptify(RefMap &M);
+
+    std::pair<NodeSet,bool> getAllReachingDefsRecImpl(RegisterRef RefRR,
+        NodeAddr<RefNode*> RefA, NodeSet &Visited, const NodeSet &Defs,
+        unsigned Nest, unsigned MaxNest);
+  };
+} // namespace rdf
+} // namespace llvm
+
+#endif // LLVM_CODEGEN_RDFLIVENESS_H

include/llvm/CodeGen/RDFRegisters.h

+//===--- RDFRegisters.h -----------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_RDFREGISTERS_H
+#define LLVM_CODEGEN_RDFREGISTERS_H
+
+#include "llvm/ADT/BitVector.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+
+#include <set>
+#include <unordered_map>
+#include <vector>
+
+namespace llvm {
+namespace rdf {
+
+  typedef uint32_t RegisterId;
+
+  // Template class for a map translating uint32_t into arbitrary types.
+  // The map will act like an indexed set: upon insertion of a new object,
+  // it will automatically assign a new index to it. Index of 0 is treated
+  // as invalid and is never allocated.
+  template <typename T, unsigned N = 32>
+  struct IndexedSet {
+    IndexedSet() : Map() { Map.reserve(N); }
+
+    T get(uint32_t Idx) const {
+      // Index Idx corresponds to Map[Idx-1].
+      assert(Idx != 0 && !Map.empty() && Idx-1 < Map.size());
+      return Map[Idx-1];
+    }
+
+    uint32_t insert(T Val) {
+      // Linear search.
+      auto F = llvm::find(Map, Val);
+      if (F != Map.end())
+        return F - Map.begin() + 1;
+      Map.push_back(Val);
+      return Map.size();  // Return actual_index + 1.
+    }
+
+    uint32_t find(T Val) const {
+      auto F = llvm::find(Map, Val);
+      assert(F != Map.end());
+      return F - Map.begin() + 1;
+    }
+
+    typedef typename std::vector<T>::const_iterator const_iterator;
+    const_iterator begin() const { return Map.begin(); }
+    const_iterator end() const { return Map.end(); }
+
+  private:
+    std::vector<T> Map;
+  };
+
+  struct RegisterRef {
+    RegisterId Reg = 0;
+    LaneBitmask Mask = LaneBitmask::getNone();
+
+    RegisterRef() = default;
+    explicit RegisterRef(RegisterId R, LaneBitmask M = LaneBitmask::getAll())
+      : Reg(R), Mask(R != 0 ? M : LaneBitmask::getNone()) {}
+
+    operator bool() const {
+      return Reg != 0 && Mask.any();
+    }
+    bool operator== (const RegisterRef &RR) const {
+      return Reg == RR.Reg && Mask == RR.Mask;
+    }
+    bool operator!= (const RegisterRef &RR) const {
+      return !operator==(RR);
+    }
+    bool operator< (const RegisterRef &RR) const {
+      return Reg < RR.Reg || (Reg == RR.Reg && Mask < RR.Mask);
+    }
+  };
+
+
+  struct PhysicalRegisterInfo {
+    PhysicalRegisterInfo(const TargetRegisterInfo &tri,
+                         const MachineFunction &mf);
+
+    static bool isRegMaskId(RegisterId R) {
+      return TargetRegisterInfo::isStackSlot(R);
+    }
+    RegisterId getRegMaskId(const uint32_t *RM) const {
+      return TargetRegisterInfo::index2StackSlot(RegMasks.find(RM));
+    }
+    const uint32_t *getRegMaskBits(RegisterId R) const {
+      return RegMasks.get(TargetRegisterInfo::stackSlot2Index(R));
+    }
+    RegisterRef normalize(RegisterRef RR) const;
+
+    bool alias(RegisterRef RA, RegisterRef RB) const {
+      if (!isRegMaskId(RA.Reg))
+        return !isRegMaskId(RB.Reg) ? aliasRR(RA, RB) : aliasRM(RA, RB);
+      return !isRegMaskId(RB.Reg) ? aliasRM(RB, RA) : aliasMM(RA, RB);
+    }
+    std::set<RegisterId> getAliasSet(RegisterId Reg) const;
+
+    RegisterRef getRefForUnit(uint32_t U) const {
+      return RegisterRef(UnitInfos[U].Reg, UnitInfos[U].Mask);
+    }
+
+    const TargetRegisterInfo &getTRI() const { return TRI; }
+
+  private:
+    struct RegInfo {
+      const TargetRegisterClass *RegClass = nullptr;
+    };
+    struct UnitInfo {
+      RegisterId Reg = 0;
+      LaneBitmask Mask;
+    };
+
+    const TargetRegisterInfo &TRI;
+    std::vector<RegInfo> RegInfos;
+    std::vector<UnitInfo> UnitInfos;
+    IndexedSet<const uint32_t*> RegMasks;
+
+    bool aliasRR(RegisterRef RA, RegisterRef RB) const;
+    bool aliasRM(RegisterRef RR, RegisterRef RM) const;
+    bool aliasMM(RegisterRef RM, RegisterRef RN) const;
+  };
+
+
+  struct RegisterAggr {
+    RegisterAggr(const PhysicalRegisterInfo &pri)
+        : Units(pri.getTRI().getNumRegUnits()), PRI(pri) {}
+    RegisterAggr(const RegisterAggr &RG) = default;
+
+    bool empty() const { return Units.empty(); }
+    bool hasAliasOf(RegisterRef RR) const;
+    bool hasCoverOf(RegisterRef RR) const;
+    static bool isCoverOf(RegisterRef RA, RegisterRef RB,
+                          const PhysicalRegisterInfo &PRI) {
+      return RegisterAggr(PRI).insert(RA).hasCoverOf(RB);
+    }
+
+    RegisterAggr &insert(RegisterRef RR);
+    RegisterAggr &insert(const RegisterAggr &RG);
+    RegisterAggr &intersect(RegisterRef RR);
+    RegisterAggr &intersect(const RegisterAggr &RG);
+    RegisterAggr &clear(RegisterRef RR);
+    RegisterAggr &clear(const RegisterAggr &RG);
+
+    RegisterRef intersectWith(RegisterRef RR) const;
+    RegisterRef clearIn(RegisterRef RR) const;
+    RegisterRef makeRegRef() const;
+
+    void print(raw_ostream &OS) const;
+
+    struct rr_iterator {
+      typedef std::map<RegisterId,LaneBitmask> MapType;
+    private:
+      MapType Masks;
+      MapType::iterator Pos;
+      unsigned Index;
+      const RegisterAggr *Owner;
+    public:
+      rr_iterator(const RegisterAggr &RG, bool End);
+      RegisterRef operator*() const {
+        return RegisterRef(Pos->first, Pos->second);
+      }
+      rr_iterator &operator++() {
+        ++Pos;
+        ++Index;
+        return *this;
+      }
+      bool operator==(const rr_iterator &I) const {
+        assert(Owner == I.Owner);
+        return Index == I.Index;
+      }
+      bool operator!=(const rr_iterator &I) const {
+        return !(*this == I);
+      }
+    };
+
+    rr_iterator rr_begin() const {
+      return rr_iterator(*this, false);
+    }
+    rr_iterator rr_end() const {
+      return rr_iterator(*this, true);
+    }
+
+  private:
+    BitVector Units;
+    const PhysicalRegisterInfo &PRI;
+  };
+
+
+  // Optionally print the lane mask, if it is not ~0.
+  struct PrintLaneMaskOpt {
+    PrintLaneMaskOpt(LaneBitmask M) : Mask(M) {}
+    LaneBitmask Mask;
+  };
+  raw_ostream &operator<< (raw_ostream &OS, const PrintLaneMaskOpt &P);
+
+} // namespace rdf
+} // namespace llvm
+
+#endif // LLVM_CODEGEN_RDFREGISTERS_H
+

lib/CodeGen/CMakeLists.txt

add_llvm_library(LLVMCodeGen
   PHIElimination.cpp
   PHIEliminationUtils.cpp
   PostRAHazardRecognizer.cpp
   PostRASchedulerList.cpp
   PreISelIntrinsicLowering.cpp
   ProcessImplicitDefs.cpp
   PrologEpilogInserter.cpp
   PseudoSourceValue.cpp
+  RDFGraph.cpp
+  RDFLiveness.cpp
+  RDFRegisters.cpp
   RegAllocBase.cpp
   RegAllocBasic.cpp
   RegAllocFast.cpp
   RegAllocGreedy.cpp
   RegAllocPBQP.cpp
   RegisterClassInfo.cpp
   RegisterCoalescer.cpp
   RegisterPressure.cpp

lib/CodeGen/RDFGraph.cpp

+//===--- RDFGraph.cpp -----------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Target-independent, SSA-based data flow graph for register data flow (RDF).
+//
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineDominanceFrontier.h"
+#include "llvm/CodeGen/MachineDominators.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineOperand.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/RDFGraph.h"
+#include "llvm/IR/Function.h"
+#include "llvm/MC/LaneBitmask.h"
+#include "llvm/MC/MCInstrDesc.h"
+#include "llvm/MC/MCRegisterInfo.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetLowering.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include <algorithm>
+#include <cassert>
+#include <cstdint>
+#include <cstring>
+#include <iterator>
+#include <utility>
+#include <vector>
+
+using namespace llvm;
+using namespace rdf;
+
+// Printing functions. Have them here first, so that the rest of the code
+// can use them.
+namespace llvm {
+namespace rdf {
+
+raw_ostream &operator<< (raw_ostream &OS, const PrintLaneMaskOpt &P) {
+  if (!P.Mask.all())
+    OS << ':' << PrintLaneMask(P.Mask);
+  return OS;
+}
+
+template<>
+raw_ostream &operator<< (raw_ostream &OS, const Print<RegisterRef> &P) {
+  auto &TRI = P.G.getTRI();
+  if (P.Obj.Reg > 0 && P.Obj.Reg < TRI.getNumRegs())
+    OS << TRI.getName(P.Obj.Reg);
+  else
+    OS << '#' << P.Obj.Reg;
+  OS << PrintLaneMaskOpt(P.Obj.Mask);
+  return OS;
+}
+
+template<>
+raw_ostream &operator<< (raw_ostream &OS, const Print<NodeId> &P) {
+  auto NA = P.G.addr<NodeBase*>(P.Obj);
+  uint16_t Attrs = NA.Addr->getAttrs();
+  uint16_t Kind = NodeAttrs::kind(Attrs);
+  uint16_t Flags = NodeAttrs::flags(Attrs);
+  switch (NodeAttrs::type(Attrs)) {
+    case NodeAttrs::Code:
+      switch (Kind) {
+        case NodeAttrs::Func:   OS << 'f'; break;
+        case NodeAttrs::Block:  OS << 'b'; break;
+        case NodeAttrs::Stmt:   OS << 's'; break;
+        case NodeAttrs::Phi:    OS << 'p'; break;
+        default:                OS << "c?"; break;
+      }
+      break;
+    case NodeAttrs::Ref:
+      if (Flags & NodeAttrs::Undef)
+        OS << '/';
+      if (Flags & NodeAttrs::Dead)
+        OS << '\\';
+      if (Flags & NodeAttrs::Preserving)
+        OS << '+';
+      if (Flags & NodeAttrs::Clobbering)
+        OS << '~';
+      switch (Kind) {
+        case NodeAttrs::Use:    OS << 'u'; break;
+        case NodeAttrs::Def:    OS << 'd'; break;
+        case NodeAttrs::Block:  OS << 'b'; break;
+        default:                OS << "r?"; break;
+      }
+      break;
+    default:
+      OS << '?';
+      break;
+  }
+  OS << P.Obj;
+  if (Flags & NodeAttrs::Shadow)
+    OS << '"';
+  return OS;
+}
+
+static void printRefHeader(raw_ostream &OS, const NodeAddr<RefNode*> RA,
+                const DataFlowGraph &G) {
+  OS << Print<NodeId>(RA.Id, G) << '<'
+     << Print<RegisterRef>(RA.Addr->getRegRef(G), G) << '>';
+  if (RA.Addr->getFlags() & NodeAttrs::Fixed)
+    OS << '!';
+}
+
+template<>
+raw_ostream &operator<< (raw_ostream &OS, const Print<NodeAddr<DefNode*>> &P) {
+  printRefHeader(OS, P.Obj, P.G);
+  OS << '(';
+  if (NodeId N = P.Obj.Addr->getReachingDef())
+    OS << Print<NodeId>(N, P.G);
+  OS << ',';
+  if (NodeId N = P.Obj.Addr->getReachedDef())
+    OS << Print<NodeId>(N, P.G);
+  OS << ',';
+  if (NodeId N = P.Obj.Addr->getReachedUse())
+    OS << Print<NodeId>(N, P.G);
+  OS << "):";
+  if (NodeId N = P.Obj.Addr->getSibling())
+    OS << Print<NodeId>(N, P.G);
+  return OS;
+}
+
+template<>
+raw_ostream &operator<< (raw_ostream &OS, const Print<NodeAddr<UseNode*>> &P) {
+  printRefHeader(OS, P.Obj, P.G);
+  OS << '(';
+  if (NodeId N = P.Obj.Addr->getReachingDef())
+    OS << Print<NodeId>(N, P.G);
+  OS << "):";
+  if (NodeId N = P.Obj.Addr->getSibling())
+    OS << Print<NodeId>(N, P.G);
+  return OS;
+}
+
+template<>
+raw_ostream &operator<< (raw_ostream &OS,
+      const Print<NodeAddr<PhiUseNode*>> &P) {
+  printRefHeader(OS, P.Obj, P.G);
+  OS << '(';
+  if (NodeId N = P.Obj.Addr->getReachingDef())
+    OS << Print<NodeId>(N, P.G);
+  OS << ',';
+  if (NodeId N = P.Obj.Addr->getPredecessor())
+    OS << Print<NodeId>(N, P.G);
+  OS << "):";
+  if (NodeId N = P.Obj.Addr->getSibling())
+    OS << Print<NodeId>(N, P.G);
+  return OS;
+}
+
+template<>
+raw_ostream &operator<< (raw_ostream &OS, const Print<NodeAddr<RefNode*>> &P) {
+  switch (P.Obj.Addr->getKind()) {
+    case NodeAttrs::Def:
+      OS << PrintNode<DefNode*>(P.Obj, P.G);
+      break;
+    case NodeAttrs::Use:
+      if (P.Obj.Addr->getFlags() & NodeAttrs::PhiRef)
+        OS << PrintNode<PhiUseNode*>(P.Obj, P.G);
+      else
+        OS << PrintNode<UseNode*>(P.Obj, P.G);
+      break;
+  }
+  return OS;
+}
+
+template<>
+raw_ostream &operator<< (raw_ostream &OS, const Print<NodeList> &P) {
+  unsigned N = P.Obj.size();
+  for (auto I : P.Obj) {
+    OS << Print<NodeId>(I.Id, P.G);
+    if (--N)
+      OS << ' ';
+  }
+  return OS;
+}
+
+template<>
+raw_ostream &operator<< (raw_ostream &OS, const Print<NodeSet> &P) {
+  unsigned N = P.Obj.size();
+  for (auto I : P.Obj) {
+    OS << Print<NodeId>(I, P.G);
+    if (--N)
+      OS << ' ';
+  }
+  return OS;
+}
+
+namespace {
+
+  template <typename T>
+  struct PrintListV {
+    PrintListV(const NodeList &L, const DataFlowGraph &G) : List(L), G(G) {}
+
+    typedef T Type;
+    const NodeList &List;
+    const DataFlowGraph &G;
+  };
+
+  template <typename T>
+  raw_ostream &operator<< (raw_ostream &OS, const PrintListV<T> &P) {
+    unsigned N = P.List.size();
+    for (NodeAddr<T> A : P.List) {
+      OS << PrintNode<T>(A, P.G);
+      if (--N)
+        OS << ", ";
+    }
+    return OS;
+  }
+
+} // end anonymous namespace
+
+template<>
+raw_ostream &operator<< (raw_ostream &OS, const Print<NodeAddr<PhiNode*>> &P) {
+  OS << Print<NodeId>(P.Obj.Id, P.G) << ": phi ["
+     << PrintListV<RefNode*>(P.Obj.Addr->members(P.G), P.G) << ']';
+  return OS;
+}
+
+template<>
+raw_ostream &operator<< (raw_ostream &OS,
+      const Print<NodeAddr<StmtNode*>> &P) {
+  const MachineInstr &MI = *P.Obj.Addr->getCode();
+  unsigned Opc = MI.getOpcode();
+  OS << Print<NodeId>(P.Obj.Id, P.G) << ": " << P.G.getTII().getName(Opc);
+  // Print the target for calls and branches (for readability).
+  if (MI.isCall() || MI.isBranch()) {
+    MachineInstr::const_mop_iterator T =
+          llvm::find_if(MI.operands(),
+                        [] (const MachineOperand &Op) -> bool {
+                          return Op.isMBB() || Op.isGlobal() || Op.isSymbol();
+                        });
+    if (T != MI.operands_end()) {
+      OS << ' ';
+      if (T->isMBB())
+        OS << "BB#" << T->getMBB()->getNumber();
+      else if (T->isGlobal())
+        OS << T->getGlobal()->getName();
+      else if (T->isSymbol())
+        OS << T->getSymbolName();
+    }
+  }
+  OS << " [" << PrintListV<RefNode*>(P.Obj.Addr->members(P.G), P.G) << ']';
+  return OS;
+}
+
+template<>
+raw_ostream &operator<< (raw_ostream &OS,
+      const Print<NodeAddr<InstrNode*>> &P) {
+  switch (P.Obj.Addr->getKind()) {
+    case NodeAttrs::Phi:
+      OS << PrintNode<PhiNode*>(P.Obj, P.G);
+      break;
+    case NodeAttrs::Stmt:
+      OS << PrintNode<StmtNode*>(P.Obj, P.G);
+      break;
+    default:
+      OS << "instr? " << Print<NodeId>(P.Obj.Id, P.G);
+      break;
+  }
+  return OS;
+}
+
+template<>
+raw_ostream &operator<< (raw_ostream &OS,
+      const Print<NodeAddr<BlockNode*>> &P) {
+  MachineBasicBlock *BB = P.Obj.Addr->getCode();
+  unsigned NP = BB->pred_size();
+  std::vector<int> Ns;
+  auto PrintBBs = [&OS] (std::vector<int> Ns) -> void {
+    unsigned N = Ns.size();
+    for (int I : Ns) {
+      OS << "BB#" << I;
+      if (--N)
+        OS << ", ";
+    }
+  };
+
+  OS << Print<NodeId>(P.Obj.Id, P.G) << ": --- BB#" << BB->getNumber()
+     << " --- preds(" << NP << "): ";
+  for (MachineBasicBlock *B : BB->predecessors())
+    Ns.push_back(B->getNumber());
+  PrintBBs(Ns);
+
+  unsigned NS = BB->succ_size();
+  OS << "  succs(" << NS << "): ";
+  Ns.clear();
+  for (MachineBasicBlock *B : BB->successors())
+    Ns.push_back(B->getNumber());
+  PrintBBs(Ns);
+  OS << '\n';
+
+  for (auto I : P.Obj.Addr->members(P.G))
+    OS << PrintNode<InstrNode*>(I, P.G) << '\n';
+  return OS;
+}
+
+template<>
+raw_ostream &operator<< (raw_ostream &OS,
+      const Print<NodeAddr<FuncNode*>> &P) {
+  OS << "DFG dump:[\n" << Print<NodeId>(P.Obj.Id, P.G) << ": Function: "
+     << P.Obj.Addr->getCode()->getName() << '\n';
+  for (auto I : P.Obj.Addr->members(P.G))
+    OS << PrintNode<BlockNode*>(I, P.G) << '\n';
+  OS << "]\n";
+  return OS;
+}
+
+template<>
+raw_ostream &operator<< (raw_ostream &OS, const Print<RegisterSet> &P) {
+  OS << '{';
+  for (auto I : P.Obj)
+    OS << ' ' << Print<RegisterRef>(I, P.G);
+  OS << " }";
+  return OS;
+}
+
+template<>
+raw_ostream &operator<< (raw_ostream &OS, const Print<RegisterAggr> &P) {
+  P.Obj.print(OS);
+  return OS;
+}
+
+template<>
+raw_ostream &operator<< (raw_ostream &OS,
+      const Print<DataFlowGraph::DefStack> &P) {
+  for (auto I = P.Obj.top(), E = P.Obj.bottom(); I != E; ) {
+    OS << Print<NodeId>(I->Id, P.G)
+       << '<' << Print<RegisterRef>(I->Addr->getRegRef(P.G), P.G) << '>';
+    I.down();
+    if (I != E)
+      OS << ' ';
+  }
+  return OS;
+}
+
+} // end namespace rdf
+} // end namespace llvm
+
+// Node allocation functions.
+//
+// Node allocator is like a slab memory allocator: it allocates blocks of
+// memory in sizes that are multiples of the size of a node. Each block has
+// the same size. Nodes are allocated from the currently active block, and
+// when it becomes full, a new one is created.
+// There is a mapping scheme between node id and its location in a block,
+// and within that block is described in the header file.
+//
+void NodeAllocator::startNewBlock() {
+  void *T = MemPool.Allocate(NodesPerBlock*NodeMemSize, NodeMemSize);
+  char *P = static_cast<char*>(T);
+  Blocks.push_back(P);
+  // Check if the block index is still within the allowed range, i.e. less
+  // than 2^N, where N is the number of bits in NodeId for the block index.
+  // BitsPerIndex is the number of bits per node index.
+  assert((Blocks.size() < ((size_t)1 << (8*sizeof(NodeId)-BitsPerIndex))) &&
+         "Out of bits for block index");
+  ActiveEnd = P;
+}
+
+bool NodeAllocator::needNewBlock() {
+  if (Blocks.empty())
+    return true;
+
+  char *ActiveBegin = Blocks.back();
+  uint32_t Index = (ActiveEnd-ActiveBegin)/NodeMemSize;
+  return Index >= NodesPerBlock;
+}
+
+NodeAddr<NodeBase*> NodeAllocator::New() {
+  if (needNewBlock())
+    startNewBlock();
+
+  uint32_t ActiveB = Blocks.size()-1;
+  uint32_t Index = (ActiveEnd - Blocks[ActiveB])/NodeMemSize;
+  NodeAddr<NodeBase*> NA = { reinterpret_cast<NodeBase*>(ActiveEnd),
+                             makeId(ActiveB, Index) };
+  ActiveEnd += NodeMemSize;
+  return NA;
+}
+
+NodeId NodeAllocator::id(const NodeBase *P) const {
+  uintptr_t A = reinterpret_cast<uintptr_t>(P);
+  for (unsigned i = 0, n = Blocks.size(); i != n; ++i) {
+    uintptr_t B = reinterpret_cast<uintptr_t>(Blocks[i]);
+    if (A < B || A >= B + NodesPerBlock*NodeMemSize)
+      continue;
+    uint32_t Idx = (A-B)/NodeMemSize;
+    return makeId(i, Idx);
+  }
+  llvm_unreachable("Invalid node address");
+}
+
+void NodeAllocator::clear() {
+  MemPool.Reset();
+  Blocks.clear();
+  ActiveEnd = nullptr;
+}
+
+// Insert node NA after "this" in the circular chain.
+void NodeBase::append(NodeAddr<NodeBase*> NA) {
+  NodeId Nx = Next;
+  // If NA is already "next", do nothing.
+  if (Next != NA.Id) {
+    Next = NA.Id;
+    NA.Addr->Next = Nx;
+  }
+}
+
+// Fundamental node manipulator functions.
+
+// Obtain the register reference from a reference node.
+RegisterRef RefNode::getRegRef(const DataFlowGraph &G) const {
+  assert(NodeAttrs::type(Attrs) == NodeAttrs::Ref);
+  if (NodeAttrs::flags(Attrs) & NodeAttrs::PhiRef)
+    return G.unpack(Ref.PR);
+  assert(Ref.Op != nullptr);
+  return G.makeRegRef(*Ref.Op);
+}
+
+// Set the register reference in the reference node directly (for references
+// in phi nodes).
+void RefNode::setRegRef(RegisterRef RR, DataFlowGraph &G) {
+  assert(NodeAttrs::type(Attrs) == NodeAttrs::Ref);
+  assert(NodeAttrs::flags(Attrs) & NodeAttrs::PhiRef);
+  Ref.PR = G.pack(RR);
+}
+
+// Set the register reference in the reference node based on a machine
+// operand (for references in statement nodes).
+void RefNode::setRegRef(MachineOperand *Op, DataFlowGraph &G) {
+  assert(NodeAttrs::type(Attrs) == NodeAttrs::Ref);
+  assert(!(NodeAttrs::flags(Attrs) & NodeAttrs::PhiRef));
+  (void)G;
+  Ref.Op = Op;
+}
+
+// Get the owner of a given reference node.
+NodeAddr<NodeBase*> RefNode::getOwner(const DataFlowGraph &G) {
+  NodeAddr<NodeBase*> NA = G.addr<NodeBase*>(getNext());
+
+  while (NA.Addr != this) {
+    if (NA.Addr->getType() == NodeAttrs::Code)
+      return NA;
+    NA = G.addr<NodeBase*>(NA.Addr->getNext());
+  }
+  llvm_unreachable("No owner in circular list");
+}
+
+// Connect the def node to the reaching def node.
+void DefNode::linkToDef(NodeId Self, NodeAddr<DefNode*> DA) {
+  Ref.RD = DA.Id;
+  Ref.Sib = DA.Addr->getReachedDef();
+  DA.Addr->setReachedDef(Self);
+}
+
+// Connect the use node to the reaching def node.
+void UseNode::linkToDef(NodeId Self, NodeAddr<DefNode*> DA) {
+  Ref.RD = DA.Id;
+  Ref.Sib = DA.Addr->getReachedUse();
+  DA.Addr->setReachedUse(Self);
+}
+
+// Get the first member of the code node.
+NodeAddr<NodeBase*> CodeNode::getFirstMember(const DataFlowGraph &G) const {
+  if (Code.FirstM == 0)
+    return NodeAddr<NodeBase*>();
+  return G.addr<NodeBase*>(Code.FirstM);
+}
+
+// Get the last member of the code node.
+NodeAddr<NodeBase*> CodeNode::getLastMember(const DataFlowGraph &G) const {
+  if (Code.LastM == 0)
+    return NodeAddr<NodeBase*>();
+  return G.addr<NodeBase*>(Code.LastM);
+}
+
+// Add node NA at the end of the member list of the given code node.
+void CodeNode::addMember(NodeAddr<NodeBase*> NA, const DataFlowGraph &G) {
+  NodeAddr<NodeBase*> ML = getLastMember(G);
+  if (ML.Id != 0) {
+    ML.Addr->append(NA);
+  } else {
+    Code.FirstM = NA.Id;
+    NodeId Self = G.id(this);
+    NA.Addr->setNext(Self);
+  }
+  Code.LastM = NA.Id;
+}
+
+// Add node NA after member node MA in the given code node.
+void CodeNode::addMemberAfter(NodeAddr<NodeBase*> MA, NodeAddr<NodeBase*> NA,
+      const DataFlowGraph &G) {
+  MA.Addr->append(NA);
+  if (Code.LastM == MA.Id)
+    Code.LastM = NA.Id;
+}
+
+// Remove member node NA from the given code node.
+void CodeNode::removeMember(NodeAddr<NodeBase*> NA, const DataFlowGraph &G) {
+  NodeAddr<NodeBase*> MA = getFirstMember(G);
+  assert(MA.Id != 0);
+
+  // Special handling if the member to remove is the first member.
+  if (MA.Id == NA.Id) {
+    if (Code.LastM == MA.Id) {
+      // If it is the only member, set both first and last to 0.
+      Code.FirstM = Code.LastM = 0;
+    } else {
+      // Otherwise, advance the first member.
+      Code.FirstM = MA.Addr->getNext();
+    }
+    return;
+  }
+
+  while (MA.Addr != this) {
+    NodeId MX = MA.Addr->getNext();
+    if (MX == NA.Id) {
+      MA.Addr->setNext(NA.Addr->getNext());
+      // If the member to remove happens to be the last one, update the
+      // LastM indicator.
+      if (Code.LastM == NA.Id)
+        Code.LastM = MA.Id;
+      return;
+    }
+    MA = G.addr<NodeBase*>(MX);
+  }
+  llvm_unreachable("No such member");
+}
+
+// Return the list of all members of the code node.
+NodeList CodeNode::members(const DataFlowGraph &G) const {
+  static auto True = [] (NodeAddr<NodeBase*>) -> bool { return true; };
+  return members_if(True, G);
+}
+
+// Return the owner of the given instr node.
+NodeAddr<NodeBase*> InstrNode::getOwner(const DataFlowGraph &G) {
+  NodeAddr<NodeBase*> NA = G.addr<NodeBase*>(getNext());
+
+  while (NA.Addr != this) {
+    assert(NA.Addr->getType() == NodeAttrs::Code);
+    if (NA.Addr->getKind() == NodeAttrs::Block)
+      return NA;
+    NA = G.addr<NodeBase*>(NA.Addr->getNext());
+  }
+  llvm_unreachable("No owner in circular list");
+}
+
+// Add the phi node PA to the given block node.
+void BlockNode::addPhi(NodeAddr<PhiNode*> PA, const DataFlowGraph &G) {
+  NodeAddr<NodeBase*> M = getFirstMember(G);
+  if (M.Id == 0) {
+    addMember(PA, G);
+    return;
+  }
+
+  assert(M.Addr->getType() == NodeAttrs::Code);
+  if (M.Addr->getKind() == NodeAttrs::Stmt) {
+    // If the first member of the block is a statement, insert the phi as
+    // the first member.
+    Code.FirstM = PA.Id;
+    PA.Addr->setNext(M.Id);
+  } else {
+    // If the first member is a phi, find the last phi, and append PA to it.
+    assert(M.Addr->getKind() == NodeAttrs::Phi);
+    NodeAddr<NodeBase*> MN = M;
+    do {
+      M = MN;
+      MN = G.addr<NodeBase*>(M.Addr->getNext());
+      assert(MN.Addr->getType() == NodeAttrs::Code);
+    } while (MN.Addr->getKind() == NodeAttrs::Phi);
+
+    // M is the last phi.
+    addMemberAfter(M, PA, G);
+  }
+}
+
+// Find the block node corresponding to the machine basic block BB in the
+// given func node.
+NodeAddr<BlockNode*> FuncNode::findBlock(const MachineBasicBlock *BB,
+      const DataFlowGraph &G) const {
+  auto EqBB = [BB] (NodeAddr<NodeBase*> NA) -> bool {
+    return NodeAddr<BlockNode*>(NA).Addr->getCode() == BB;
+  };
+  NodeList Ms = members_if(EqBB, G);
+  if (!Ms.empty())
+    return Ms[0];
+  return NodeAddr<BlockNode*>();
+}
+
+// Get the block node for the entry block in the given function.
+NodeAddr<BlockNode*> FuncNode::getEntryBlock(const DataFlowGraph &G) {
+  MachineBasicBlock *EntryB = &getCode()->front();
+  return findBlock(EntryB, G);
+}
+
+// Target operand information.
+//
+
+// For a given instruction, check if there are any bits of RR that can remain
+// unchanged across this def.
+bool TargetOperandInfo::isPreserving(const MachineInstr &In, unsigned OpNum)
+      const {
+  return TII.isPredicated(In);
+}
+
+// Check if the definition of RR produces an unspecified value.
+bool TargetOperandInfo::isClobbering(const MachineInstr &In, unsigned OpNum)
+      const {
+  const MachineOperand &Op = In.getOperand(OpNum);
+  if (Op.isRegMask())
+    return true;
+  assert(Op.isReg());
+  if (In.isCall())
+    if (Op.isDef() && Op.isDead())
+      return true;
+  return false;
+}
+
+// Check if the given instruction specifically requires
+bool TargetOperandInfo::isFixedReg(const MachineInstr &In, unsigned OpNum)
+      const {
+  if (In.isCall() || In.isReturn() || In.isInlineAsm())
+    return true;
+  // Check for a tail call.
+  if (In.isBranch())
+    for (const MachineOperand &O : In.operands())
+      if (O.isGlobal() || O.isSymbol())
+        return true;
+
+  const MCInstrDesc &D = In.getDesc();
+  if (!D.getImplicitDefs() && !D.getImplicitUses())
+    return false;
+  const MachineOperand &Op = In.getOperand(OpNum);
+  // If there is a sub-register, treat the operand as non-fixed. Currently,
+  // fixed registers are those that are listed in the descriptor as implicit
+  // uses or defs, and those lists do not allow sub-registers.
+  if (Op.getSubReg() != 0)
+    return false;
+  RegisterId Reg = Op.getReg();
+  const MCPhysReg *ImpR = Op.isDef() ? D.getImplicitDefs()
+                                     : D.getImplicitUses();
+  if (!ImpR)
+    return false;
+  while (*ImpR)
+    if (*ImpR++ == Reg)
+      return true;
+  return false;
+}
+
+//
+// The data flow graph construction.
+//
+
+DataFlowGraph::DataFlowGraph(MachineFunction &mf, const TargetInstrInfo &tii,
+      const TargetRegisterInfo &tri, const MachineDominatorTree &mdt,
+      const MachineDominanceFrontier &mdf, const TargetOperandInfo &toi)
+    : MF(mf), TII(tii), TRI(tri), PRI(tri, mf), MDT(mdt), MDF(mdf), TOI(toi),
+      LiveIns(PRI) {
+}
+
+// The implementation of the definition stack.
+// Each register reference has its own definition stack. In particular,
+// for a register references "Reg" and "Reg:subreg" will each have their
+// own definition stacks.
+
+// Construct a stack iterator.
+DataFlowGraph::DefStack::Iterator::Iterator(const DataFlowGraph::DefStack &S,
+      bool Top) : DS(S) {
+  if (!Top) {
+    // Initialize to bottom.
+    Pos = 0;
+    return;
+  }
+  // Initialize to the top, i.e. top-most non-delimiter (or 0, if empty).
+  Pos = DS.Stack.size();
+  while (Pos > 0 && DS.isDelimiter(DS.Stack[Pos-1]))
+    Pos--;
+}
+
+// Return the size of the stack, including block delimiters.
+unsigned DataFlowGraph::DefStack::size() const {
+  unsigned S = 0;
+  for (auto I = top(), E = bottom(); I != E; I.down())
+    S++;
+  return S;
+}
+
+// Remove the top entry from the stack. Remove all intervening delimiters
+// so that after this, the stack is either empty, or the top of the stack
+// is a non-delimiter.
+void DataFlowGraph::DefStack::pop() {
+  assert(!empty());
+  unsigned P = nextDown(Stack.size());
+  Stack.resize(P);
+}
+
+// Push a delimiter for block node N on the stack.
+void DataFlowGraph::DefStack::start_block(NodeId N) {
+  assert(N != 0);
+  Stack.push_back(NodeAddr<DefNode*>(nullptr, N));
+}
+
+// Remove all nodes from the top of the stack, until the delimited for
+// block node N is encountered. Remove the delimiter as well. In effect,
+// this will remove from the stack all definitions from block N.
+void DataFlowGraph::DefStack::clear_block(NodeId N) {
+  assert(N != 0);
+  unsigned P = Stack.size();
+  while (P > 0) {
+    bool Found = isDelimiter(Stack[P-1], N);
+    P--;
+    if (Found)
+      break;
+  }
+  // This will also remove the delimiter, if found.
+  Stack.resize(P);
+}
+
+// Move the stack iterator up by one.
+unsigned DataFlowGraph::DefStack::nextUp(unsigned P) const {
+  // Get the next valid position after P (skipping all delimiters).
+  // The input position P does not have to point to a non-delimiter.
+  unsigned SS = Stack.size();
+  bool IsDelim;
+  assert(P < SS);
+  do {
+    P++;
+    IsDelim = isDelimiter(Stack[P-1]);
+  } while (P < SS && IsDelim);
+  assert(!IsDelim);
+  return P;
+}
+
+// Move the stack iterator down by one.
+unsigned DataFlowGraph::DefStack::nextDown(unsigned P) const {
+  // Get the preceding valid position before P (skipping all delimiters).
+  // The input position P does not have to point to a non-delimiter.
+  assert(P > 0 && P <= Stack.size());
+  bool IsDelim = isDelimiter(Stack[P-1]);
+  do {
+    if (--P == 0)
+      break;
+    IsDelim = isDelimiter(Stack[P-1]);
+  } while (P > 0 && IsDelim);
+  assert(!IsDelim);
+  return P;
+}
+
+// Register information.
+
+RegisterSet DataFlowGraph::getLandingPadLiveIns() const {
+  RegisterSet LR;
+  const Function &F = *MF.getFunction();
+  const Constant *PF = F.hasPersonalityFn() ? F.getPersonalityFn()
+                                            : nullptr;
+  const TargetLowering &TLI = *MF.getSubtarget().getTargetLowering();
+  if (RegisterId R = TLI.getExceptionPointerRegister(PF))
+    LR.insert(RegisterRef(R));
+  if (RegisterId R = TLI.getExceptionSelectorRegister(PF))
+    LR.insert(RegisterRef(R));
+  return LR;
+}
+
+// Node management functions.
+
+// Get the pointer to the node with the id N.
+NodeBase *DataFlowGraph::ptr(NodeId N) const {
+  if (N == 0)
+    return nullptr;
+  return Memory.ptr(N);
+}
+
+// Get the id of the node at the address P.
+NodeId DataFlowGraph::id(const NodeBase *P) const {
+  if (P == nullptr)
+    return 0;
+  return Memory.id(P);
+}
+
+// Allocate a new node and set the attributes to Attrs.
+NodeAddr<NodeBase*> DataFlowGraph::newNode(uint16_t Attrs) {
+  NodeAddr<NodeBase*> P = Memory.New();
+  P.Addr->init();
+  P.Addr->setAttrs(Attrs);
+  return P;
+}
+
+// Make a copy of the given node B, except for the data-flow links, which
+// are set to 0.
+NodeAddr<NodeBase*> DataFlowGraph::cloneNode(const NodeAddr<NodeBase*> B) {
+  NodeAddr<NodeBase*> NA = newNode(0);
+  memcpy(NA.Addr, B.Addr, sizeof(NodeBase));
+  // Ref nodes need to have the data-flow links reset.
+  if (NA.Addr->getType() == NodeAttrs::Ref) {
+    NodeAddr<RefNode*> RA = NA;
+    RA.Addr->setReachingDef(0);
+    RA.Addr->setSibling(0);
+    if (NA.Addr->getKind() == NodeAttrs::Def) {
+      NodeAddr<DefNode*> DA = NA;
+      DA.Addr->setReachedDef(0);
+      DA.Addr->setReachedUse(0);
+    }
+  }
+  return NA;
+}
+
+// Allocation routines for specific node types/kinds.
+
+NodeAddr<UseNode*> DataFlowGraph::newUse(NodeAddr<InstrNode*> Owner,
+      MachineOperand &Op, uint16_t Flags) {
+  NodeAddr<UseNode*> UA = newNode(NodeAttrs::Ref | NodeAttrs::Use | Flags);
+  UA.Addr->setRegRef(&Op, *this);
+  return UA;
+}
+
+NodeAddr<PhiUseNode*> DataFlowGraph::newPhiUse(NodeAddr<PhiNode*> Owner,
+      RegisterRef RR, NodeAddr<BlockNode*> PredB, uint16_t Flags) {
+  NodeAddr<PhiUseNode*> PUA = newNode(NodeAttrs::Ref | NodeAttrs::Use | Flags);
+  assert(Flags & NodeAttrs::PhiRef);
+  PUA.Addr->setRegRef(RR, *this);
+  PUA.Addr->setPredecessor(PredB.Id);
+  return PUA;
+}
+
+NodeAddr<DefNode*> DataFlowGraph::newDef(NodeAddr<InstrNode*> Owner,
+      MachineOperand &Op, uint16_t Flags) {
+  NodeAddr<DefNode*> DA = newNode(NodeAttrs::Ref | NodeAttrs::Def | Flags);
+  DA.Addr->setRegRef(&Op, *this);
+  return DA;
+}
+
+NodeAddr<DefNode*> DataFlowGraph::newDef(NodeAddr<InstrNode*> Owner,
+      RegisterRef RR, uint16_t Flags) {
+  NodeAddr<DefNode*> DA = newNode(NodeAttrs::Ref | NodeAttrs::Def | Flags);
+  assert(Flags & NodeAttrs::PhiRef);
+  DA.Addr->setRegRef(RR, *this);
+  return DA;
+}
+
+NodeAddr<PhiNode*> DataFlowGraph::newPhi(NodeAddr<BlockNode*> Owner) {
+  NodeAddr<PhiNode*> PA = newNode(NodeAttrs::Code | NodeAttrs::Phi);
+  Owner.Addr->addPhi(PA, *this);
+  return PA;
+}
+
+NodeAddr<StmtNode*> DataFlowGraph::newStmt(NodeAddr<BlockNode*> Owner,
+      MachineInstr *MI) {
+  NodeAddr<StmtNode*> SA = newNode(NodeAttrs::Code | NodeAttrs::Stmt);
+  SA.Addr->setCode(MI);
+  Owner.Addr->addMember(SA, *this);
+  return SA;
+}
+
+NodeAddr<BlockNode*> DataFlowGraph::newBlock(NodeAddr<FuncNode*> Owner,
+      MachineBasicBlock *BB) {
+  NodeAddr<BlockNode*> BA = newNode(NodeAttrs::Code | NodeAttrs::Block);
+  BA.Addr->setCode(BB);
+  Owner.Addr->addMember(BA, *this);
+  return BA;
+}
+
+NodeAddr<FuncNode*> DataFlowGraph::newFunc(MachineFunction *MF) {
+  NodeAddr<FuncNode*> FA = newNode(NodeAttrs::Code | NodeAttrs::Func);
+  FA.Addr->setCode(MF);
+  return FA;
+}
+
+// Build the data flow graph.
+void DataFlowGraph::build(unsigned Options) {
+  reset();
+  Func = newFunc(&MF);
+
+  if (MF.empty())
+    return;
+
+  for (MachineBasicBlock &B : MF) {
+    NodeAddr<BlockNode*> BA = newBlock(Func, &B);
+    BlockNodes.insert(std::make_pair(&B, BA));
+    for (MachineInstr &I : B) {
+      if (I.isDebugValue())
+        continue;
+      buildStmt(BA, I);
+    }
+  }
+
+  NodeAddr<BlockNode*> EA = Func.Addr->getEntryBlock(*this);
+  NodeList Blocks = Func.Addr->members(*this);
+
+  // Collect information about block references.
+  BlockRefsMap RefM;
+  buildBlockRefs(EA, RefM);
+
+  // Collect function live-ins and entry block live-ins.
+  MachineRegisterInfo &MRI = MF.getRegInfo();
+  MachineBasicBlock &EntryB = *EA.Addr->getCode();
+  assert(EntryB.pred_empty() && "Function entry block has predecessors");
+  for (auto I = MRI.livein_begin(), E = MRI.livein_end(); I != E; ++I)
+    LiveIns.insert(RegisterRef(I->first));
+  if (MRI.tracksLiveness()) {
+    for (auto I : EntryB.liveins())
+      LiveIns.insert(RegisterRef(I.PhysReg, I.LaneMask));
+  }
+
+  // Add function-entry phi nodes for the live-in registers.
+  //for (std::pair<RegisterId,LaneBitmask> P : LiveIns) {
+  for (auto I = LiveIns.rr_begin(), E = LiveIns.rr_end(); I != E; ++I) {
+    RegisterRef RR = *I;
+    NodeAddr<PhiNode*> PA = newPhi(EA);
+    uint16_t PhiFlags = NodeAttrs::PhiRef | NodeAttrs::Preserving;
+    NodeAddr<DefNode*> DA = newDef(PA, RR, PhiFlags);
+    PA.Addr->addMember(DA, *this);
+  }
+
+  // Add phis for landing pads.
+  // Landing pads, unlike usual backs blocks, are not entered through
+  // branches in the program, or fall-throughs from other blocks. They
+  // are entered from the exception handling runtime and target's ABI
+  // may define certain registers as defined on entry to such a block.
+  RegisterSet EHRegs = getLandingPadLiveIns();
+  if (!EHRegs.empty()) {
+    for (NodeAddr<BlockNode*> BA : Blocks) {
+      const MachineBasicBlock &B = *BA.Addr->getCode();
+      if (!B.isEHPad())
+        continue;
+
+      // Prepare a list of NodeIds of the block's predecessors.
+      NodeList Preds;
+      for (MachineBasicBlock *PB : B.predecessors())
+        Preds.push_back(findBlock(PB));
+
+      // Build phi nodes for each live-in.
+      for (RegisterRef RR : EHRegs) {
+        NodeAddr<PhiNode*> PA = newPhi(BA);
+        uint16_t PhiFlags = NodeAttrs::PhiRef | NodeAttrs::Preserving;
+        // Add def:
+        NodeAddr<DefNode*> DA = newDef(PA, RR, PhiFlags);
+        PA.Addr->addMember(DA, *this);
+        // Add uses (no reaching defs for phi uses):
+        for (NodeAddr<BlockNode*> PBA : Preds) {
+          NodeAddr<PhiUseNode*> PUA = newPhiUse(PA, RR, PBA);
+          PA.Addr->addMember(PUA, *this);
+        }
+      }
+    }
+  }
+
+  // Build a map "PhiM" which will contain, for each block, the set
+  // of references that will require phi definitions in that block.
+  BlockRefsMap PhiM;
+  for (NodeAddr<BlockNode*> BA : Blocks)
+    recordDefsForDF(PhiM, RefM, BA);
+  for (NodeAddr<BlockNode*> BA : Blocks)
+    buildPhis(PhiM, RefM, BA);
+
+  // Link all the refs. This will recursively traverse the dominator tree.
+  DefStackMap DM;
+  linkBlockRefs(DM, EA);
+
+  // Finally, remove all unused phi nodes.
+  if (!(Options & BuildOptions::KeepDeadPhis))
+    removeUnusedPhis();
+}
+
+RegisterRef DataFlowGraph::makeRegRef(unsigned Reg, unsigned Sub) const {
+  assert(PhysicalRegisterInfo::isRegMaskId(Reg) ||
+         TargetRegisterInfo::isPhysicalRegister(Reg));
+  assert(Reg != 0);
+  if (Sub != 0)
+    Reg = TRI.getSubReg(Reg, Sub);
+  return RegisterRef(Reg);
+}
+
+RegisterRef DataFlowGraph::makeRegRef(const MachineOperand &Op) const {
+  assert(Op.isReg() || Op.isRegMask());
+  if (Op.isReg())
+    return makeRegRef(Op.getReg(), Op.getSubReg());
+  return RegisterRef(PRI.getRegMaskId(Op.getRegMask()), LaneBitmask::getAll());
+}
+
+RegisterRef DataFlowGraph::restrictRef(RegisterRef AR, RegisterRef BR) const {
+  if (AR.Reg == BR.Reg) {
+    LaneBitmask M = AR.Mask & BR.Mask;
+    return M.any() ? RegisterRef(AR.Reg, M) : RegisterRef();
+  }
+#ifndef NDEBUG
+//  RegisterRef NAR = PRI.normalize(AR);
+//  RegisterRef NBR = PRI.normalize(BR);
+//  assert(NAR.Reg != NBR.Reg);
+#endif
+  // This isn't strictly correct, because the overlap may happen in the
+  // part masked out.
+  if (PRI.alias(AR, BR))
+    return AR;
+  return RegisterRef();
+}
+
+// For each stack in the map DefM, push the delimiter for block B on it.
+void DataFlowGraph::markBlock(NodeId B, DefStackMap &DefM) {
+  // Push block delimiters.
+  for (auto I = DefM.begin(), E = DefM.end(); I != E; ++I)
+    I->second.start_block(B);
+}
+
+// Remove all definitions coming from block B from each stack in DefM.
+void DataFlowGraph::releaseBlock(NodeId B, DefStackMap &DefM) {
+  // Pop all defs from this block from the definition stack. Defs that were
+  // added to the map during the traversal of instructions will not have a
+  // delimiter, but for those, the whole stack will be emptied.
+  for (auto I = DefM.begin(), E = DefM.end(); I != E; ++I)
+    I->second.clear_block(B);
+
+  // Finally, remove empty stacks from the map.
+  for (auto I = DefM.begin(), E = DefM.end(), NextI = I; I != E; I = NextI) {
+    NextI = std::next(I);
+    // This preserves the validity of iterators other than I.
+    if (I->second.empty())
+      DefM.erase(I);
+  }
+}
+
+// Push all definitions from the instruction node IA to an appropriate
+// stack in DefM.
+void DataFlowGraph::pushAllDefs(NodeAddr<InstrNode*> IA, DefStackMap &DefM) {
+  pushClobbers(IA, DefM);
+  pushDefs(IA, DefM);
+}
+
+// Push all definitions from the instruction node IA to an appropriate
+// stack in DefM.
+void DataFlowGraph::pushClobbers(NodeAddr<InstrNode*> IA, DefStackMap &DefM) {
+  NodeSet Visited;
+  std::set<RegisterId> Defined;
+
+  // The important objectives of this function are:
+  // - to be able to handle instructions both while the graph is being
+  //   constructed, and after the graph has been constructed, and
+  // - maintain proper ordering of definitions on the stack for each
+  //   register reference:
+  //   - if there are two or more related defs in IA (i.e. coming from
+  //     the same machine operand), then only push one def on the stack,
+  //   - if there are multiple unrelated defs of non-overlapping
+  //     subregisters of S, then the stack for S will have both (in an
+  //     unspecified order), but the order does not matter from the data-
+  //     -flow perspective.
+
+  for (NodeAddr<DefNode*> DA : IA.Addr->members_if(IsDef, *this)) {
+    if (Visited.count(DA.Id))
+      continue;
+    if (!(DA.Addr->getFlags() & NodeAttrs::Clobbering))
+      continue;
+
+    NodeList Rel = getRelatedRefs(IA, DA);
+    NodeAddr<DefNode*> PDA = Rel.front();
+    RegisterRef RR = PDA.Addr->getRegRef(*this);
+
+    // Push the definition on the stack for the register and all aliases.
+    // The def stack traversal in linkNodeUp will check the exact aliasing.
+    DefM[RR.Reg].push(DA);
+    Defined.insert(RR.Reg);
+    for (RegisterId A : PRI.getAliasSet(RR.Reg)) {
+      // Check that we don't push the same def twice.
+      assert(A != RR.Reg);
+      if (!Defined.count(A))
+        DefM[A].push(DA);
+    }
+    // Mark all the related defs as visited.
+    for (NodeAddr<NodeBase*> T : Rel)
+      Visited.insert(T.Id);
+  }
+}
+
+// Push all definitions from the instruction node IA to an appropriate
+// stack in DefM.
+void DataFlowGraph::pushDefs(NodeAddr<InstrNode*> IA, DefStackMap &DefM) {
+  NodeSet Visited;
+#ifndef NDEBUG
+  std::set<RegisterId> Defined;
+#endif
+
+  // The important objectives of this function are:
+  // - to be able to handle instructions both while the graph is being
+  //   constructed, and after the graph has been constructed, and
+  // - maintain proper ordering of definitions on the stack for each
+  //   register reference:
+  //   - if there are two or more related defs in IA (i.e. coming from
+  //     the same machine operand), then only push one def on the stack,
+  //   - if there are multiple unrelated defs of non-overlapping
+  //     subregisters of S, then the stack for S will have both (in an
+  //     unspecified order), but the order does not matter from the data-
+  //     -flow perspective.
+
+  for (NodeAddr<DefNode*> DA : IA.Addr->members_if(IsDef, *this)) {
+    if (Visited.count(DA.Id))
+      continue;
+    if (DA.Addr->getFlags() & NodeAttrs::Clobbering)
+      continue;
+
+    NodeList Rel = getRelatedRefs(IA, DA);
+    NodeAddr<DefNode*> PDA = Rel.front();
+    RegisterRef RR = PDA.Addr->getRegRef(*this);
+#ifndef NDEBUG
+    // Assert if the register is defined in two or more unrelated defs.
+    // This could happen if there are two or more def operands defining it.
+    if (!Defined.insert(RR.Reg).second) {
+      MachineInstr *MI = NodeAddr<StmtNode*>(IA).Addr->getCode();
+      dbgs() << "Multiple definitions of register: "
+             << Print<RegisterRef>(RR, *this) << " in\n  " << *MI
+             << "in BB#" << MI->getParent()->getNumber() << '\n';
+      llvm_unreachable(nullptr);
+    }
+#endif
+    // Push the definition on the stack for the register and all aliases.
+    // The def stack traversal in linkNodeUp will check the exact aliasing.
+    DefM[RR.Reg].push(DA);
+    for (RegisterId A : PRI.getAliasSet(RR.Reg)) {
+      // Check that we don't push the same def twice.
+      assert(A != RR.Reg);
+      DefM[A].push(DA);
+    }
+    // Mark all the related defs as visited.
+    for (NodeAddr<NodeBase*> T : Rel)
+      Visited.insert(T.Id);
+  }
+}
+
+// Return the list of all reference nodes related to RA, including RA itself.
+// See "getNextRelated" for the meaning of a "related reference".
+NodeList DataFlowGraph::getRelatedRefs(NodeAddr<InstrNode*> IA,
+      NodeAddr<RefNode*> RA) const {
+  assert(IA.Id != 0 && RA.Id != 0);
+
+  NodeList Refs;
+  NodeId Start = RA.Id;
+  do {
+    Refs.push_back(RA);
+    RA = getNextRelated(IA, RA);
+  } while (RA.Id != 0 && RA.Id != Start);
+  return Refs;
+}
+
+// Clear all information in the graph.
+void DataFlowGraph::reset() {
+  Memory.clear();
+  BlockNodes.clear();
+  Func = NodeAddr<FuncNode*>();
+}
+
+// Return the next reference node in the instruction node IA that is related
+// to RA. Conceptually, two reference nodes are related if they refer to the
+// same instance of a register access, but differ in flags or other minor
+// characteristics. Specific examples of related nodes are shadow reference
+// nodes.
+// Return the equivalent of nullptr if there are no more related references.
+NodeAddr<RefNode*> DataFlowGraph::getNextRelated(NodeAddr<InstrNode*> IA,
+      NodeAddr<RefNode*> RA) const {
+  assert(IA.Id != 0 && RA.Id != 0);
+
+  auto Related = [this,RA](NodeAddr<RefNode*> TA) -> bool {
+    if (TA.Addr->getKind() != RA.Addr->getKind())
+      return false;
+    if (TA.Addr->getRegRef(*this) != RA.Addr->getRegRef(*this))
+      return false;
+    return true;
+  };
+  auto RelatedStmt = [&Related,RA](NodeAddr<RefNode*> TA) -> bool {
+    return Related(TA) &&
+           &RA.Addr->getOp() == &TA.Addr->getOp();
+  };
+  auto RelatedPhi = [&Related,RA](NodeAddr<RefNode*> TA) -> bool {
+    if (!Related(TA))
+      return false;
+    if (TA.Addr->getKind() != NodeAttrs::Use)
+      return true;
+    // For phi uses, compare predecessor blocks.
+    const NodeAddr<const PhiUseNode*> TUA = TA;
+    const NodeAddr<const PhiUseNode*> RUA = RA;
+    return TUA.Addr->getPredecessor() == RUA.Addr->getPredecessor();
+  };
+
+  RegisterRef RR = RA.Addr->getRegRef(*this);
+  if (IA.Addr->getKind() == NodeAttrs::Stmt)
+    return RA.Addr->getNextRef(RR, RelatedStmt, true, *this);
+  return RA.Addr->getNextRef(RR, RelatedPhi, true, *this);
+}
+
+// Find the next node related to RA in IA that satisfies condition P.
+// If such a node was found, return a pair where the second element is the
+// located node. If such a node does not exist, return a pair where the
+// first element is the element after which such a node should be inserted,
+// and the second element is a null-address.
+template <typename Predicate>
+std::pair<NodeAddr<RefNode*>,NodeAddr<RefNode*>>
+DataFlowGraph::locateNextRef(NodeAddr<InstrNode*> IA, NodeAddr<RefNode*> RA,
+      Predicate P) const {
+  assert(IA.Id != 0 && RA.Id != 0);
+
+  NodeAddr<RefNode*> NA;
+  NodeId Start = RA.Id;
+  while (true) {
+    NA = getNextRelated(IA, RA);
+    if (NA.Id == 0 || NA.Id == Start)
+      break;
+    if (P(NA))
+      break;
+    RA = NA;
+  }
+
+  if (NA.Id != 0 && NA.Id != Start)
+    return std::make_pair(RA, NA);
+  return std::make_pair(RA, NodeAddr<RefNode*>());
+}
+
+// Get the next shadow node in IA corresponding to RA, and optionally create
+// such a node if it does not exist.
+NodeAddr<RefNode*> DataFlowGraph::getNextShadow(NodeAddr<InstrNode*> IA,
+      NodeAddr<RefNode*> RA, bool Create) {
+  assert(IA.Id != 0 && RA.Id != 0);
+
+  uint16_t Flags = RA.Addr->getFlags() | NodeAttrs::Shadow;
+  auto IsShadow = [Flags] (NodeAddr<RefNode*> TA) -> bool {
+    return TA.Addr->getFlags() == Flags;
+  };
+  auto Loc = locateNextRef(IA, RA, IsShadow);
+  if (Loc.second.Id != 0 || !Create)
+    return Loc.second;
+
+  // Create a copy of RA and mark is as shadow.
+  NodeAddr<RefNode*> NA = cloneNode(RA);
+  NA.Addr->setFlags(Flags | NodeAttrs::Shadow);
+  IA.Addr->addMemberAfter(Loc.first, NA, *this);
+  return NA;
+}
+
+// Get the next shadow node in IA corresponding to RA. Return null-address
+// if such a node does not exist.
+NodeAddr<RefNode*> DataFlowGraph::getNextShadow(NodeAddr<InstrNode*> IA,
+      NodeAddr<RefNode*> RA) const {
+  assert(IA.Id != 0 && RA.Id != 0);
+  uint16_t Flags = RA.Addr->getFlags() | NodeAttrs::Shadow;
+  auto IsShadow = [Flags] (NodeAddr<RefNode*> TA) -> bool {
+    return TA.Addr->getFlags() == Flags;
+  };
+  return locateNextRef(IA, RA, IsShadow).second;
+}
+
+// Create a new statement node in the block node BA that corresponds to
+// the machine instruction MI.
+void DataFlowGraph::buildStmt(NodeAddr<BlockNode*> BA, MachineInstr &In) {
+  NodeAddr<StmtNode*> SA = newStmt(BA, &In);
+
+  auto isCall = [] (const MachineInstr &In) -> bool {
+    if (In.isCall())
+      return true;
+    // Is tail call?
+    if (In.isBranch()) {
+      for (const MachineOperand &Op : In.operands())
+        if (Op.isGlobal() || Op.isSymbol())
+          return true;
+      // Assume indirect branches are calls. This is for the purpose of
+      // keeping implicit operands, and so it won't hurt on intra-function
+      // indirect branches.
+      if (In.isIndirectBranch())
+        return true;
+    }
+    return false;
+  };
+
+  auto isDefUndef = [this] (const MachineInstr &In, RegisterRef DR) -> bool {
+    // This instruction defines DR. Check if there is a use operand that
+    // would make DR live on entry to the instruction.
+    for (const MachineOperand &Op : In.operands()) {
+      if (!Op.isReg() || Op.getReg() == 0 || !Op.isUse() || Op.isUndef())
+        continue;
+      RegisterRef UR = makeRegRef(Op);
+      if (PRI.alias(DR, UR))
+        return false;
+    }
+    return true;
+  };
+
+  bool IsCall = isCall(In);
+  unsigned NumOps = In.getNumOperands();
+
+  // Avoid duplicate implicit defs. This will not detect cases of implicit
+  // defs that define registers that overlap, but it is not clear how to
+  // interpret that in the absence of explicit defs. Overlapping explicit
+  // defs are likely illegal already.
+  BitVector DoneDefs(TRI.getNumRegs());
+  // Process explicit defs first.
+  for (unsigned OpN = 0; OpN < NumOps; ++OpN) {
+    MachineOperand &Op = In.getOperand(OpN);
+    if (!Op.isReg() || !Op.isDef() || Op.isImplicit())
+      continue;
+    unsigned R = Op.getReg();
+    if (!R || !TargetRegisterInfo::isPhysicalRegister(R))
+      continue;
+    uint16_t Flags = NodeAttrs::None;
+    if (TOI.isPreserving(In, OpN)) {
+      Flags |= NodeAttrs::Preserving;
+      // If the def is preserving, check if it is also undefined.
+      if (isDefUndef(In, makeRegRef(Op)))
+        Flags |= NodeAttrs::Undef;
+    }
+    if (TOI.isClobbering(In, OpN))
+      Flags |= NodeAttrs::Clobbering;
+    if (TOI.isFixedReg(In, OpN))
+      Flags |= NodeAttrs::Fixed;
+    if (IsCall && Op.isDead())
+      Flags |= NodeAttrs::Dead;
+    NodeAddr<DefNode*> DA = newDef(SA, Op, Flags);
+    SA.Addr->addMember(DA, *this);
+    assert(!DoneDefs.test(R));
+    DoneDefs.set(R);
+  }
+
+  // Process reg-masks (as clobbers).
+  BitVector DoneClobbers(TRI.getNumRegs());
+  for (unsigned OpN = 0; OpN < NumOps; ++OpN) {
+    MachineOperand &Op = In.getOperand(OpN);
+    if (!Op.isRegMask())
+      continue;
+    uint16_t Flags = NodeAttrs::Clobbering | NodeAttrs::Fixed |
+                     NodeAttrs::Dead;
+    NodeAddr<DefNode*> DA = newDef(SA, Op, Flags);
+    SA.Addr->addMember(DA, *this);
+    // Record all clobbered registers in DoneDefs.
+    const uint32_t *RM = Op.getRegMask();
+    for (unsigned i = 1, e = TRI.getNumRegs(); i != e; ++i)
+      if (!(RM[i/32] & (1u << (i%32))))
+        DoneClobbers.set(i);
+  }
+
+  // Process implicit defs, skipping those that have already been added
+  // as explicit.
+  for (unsigned OpN = 0; OpN < NumOps; ++OpN) {
+    MachineOperand &Op = In.getOperand(OpN);
+    if (!Op.isReg() || !Op.isDef() || !Op.isImplicit())
+      continue;
+    unsigned R = Op.getReg();
+    if (!R || !TargetRegisterInfo::isPhysicalRegister(R) || DoneDefs.test(R))
+      continue;
+    RegisterRef RR = makeRegRef(Op);
+    uint16_t Flags = NodeAttrs::None;
+    if (TOI.isPreserving(In, OpN)) {
+      Flags |= NodeAttrs::Preserving;
+      // If the def is preserving, check if it is also undefined.
+      if (isDefUndef(In, RR))
+        Flags |= NodeAttrs::Undef;
+    }
+    if (TOI.isClobbering(In, OpN))
+      Flags |= NodeAttrs::Clobbering;
+    if (TOI.isFixedReg(In, OpN))
+      Flags |= NodeAttrs::Fixed;
+    if (IsCall && Op.isDead()) {
+      if (DoneClobbers.test(R))
+        continue;
+      Flags |= NodeAttrs::Dead;
+    }
+    NodeAddr<DefNode*> DA = newDef(SA, Op, Flags);
+    SA.Addr->addMember(DA, *this);
+    DoneDefs.set(R);
+  }
+
+  for (unsigned OpN = 0; OpN < NumOps; ++OpN) {
+    MachineOperand &Op = In.getOperand(OpN);
+    if (!Op.isReg() || !Op.isUse())
+      continue;
+    unsigned R = Op.getReg();
+    if (!R || !TargetRegisterInfo::isPhysicalRegister(R))
+      continue;
+    uint16_t Flags = NodeAttrs::None;
+    if (Op.isUndef())
+      Flags |= NodeAttrs::Undef;
+    if (TOI.isFixedReg(In, OpN))
+      Flags |= NodeAttrs::Fixed;
+    NodeAddr<UseNode*> UA = newUse(SA, Op, Flags);
+    SA.Addr->addMember(UA, *this);
+  }
+}
+
+// Build a map that for each block will have the set of all references from
+// that block, and from all blocks dominated by it.
+void DataFlowGraph::buildBlockRefs(NodeAddr<BlockNode*> BA,
+      BlockRefsMap &RefM) {
+  RegisterSet &Refs = RefM[BA.Id];
+  MachineDomTreeNode *N = MDT.getNode(BA.Addr->getCode());
+  assert(N);
+  for (auto I : *N) {
+    MachineBasicBlock *SB = I->getBlock();
+    NodeAddr<BlockNode*> SBA = findBlock(SB);
+    buildBlockRefs(SBA, RefM);
+    const RegisterSet &RefsS = RefM[SBA.Id];
+    Refs.insert(RefsS.begin(), RefsS.end());
+  }
+
+  for (NodeAddr<InstrNode*> IA : BA.Addr->members(*this))
+    for (NodeAddr<RefNode*> RA : IA.Addr->members(*this))
+      Refs.insert(RA.Addr->getRegRef(*this));
+}
+
+// Scan all defs in the block node BA and record in PhiM the locations of
+// phi nodes corresponding to these defs.
+void DataFlowGraph::recordDefsForDF(BlockRefsMap &PhiM, BlockRefsMap &RefM,
+      NodeAddr<BlockNode*> BA) {
+  // Check all defs from block BA and record them in each block in BA's
+  // iterated dominance frontier. This information will later be used to
+  // create phi nodes.
+  MachineBasicBlock *BB = BA.Addr->getCode();
+  assert(BB);
+  auto DFLoc = MDF.find(BB);
+  if (DFLoc == MDF.end() || DFLoc->second.empty())
+    return;
+
+  // Traverse all instructions in the block and collect the set of all
+  // defined references. For each reference there will be a phi created
+  // in the block's iterated dominance frontier.
+  // This is done to make sure that each defined reference gets only one
+  // phi node, even if it is defined multiple times.
+  RegisterSet Defs;
+  for (NodeAddr<InstrNode*> IA : BA.Addr->members(*this))
+    for (NodeAddr<RefNode*> RA : IA.Addr->members_if(IsDef, *this))
+      Defs.insert(RA.Addr->getRegRef(*this));
+
+  // Calculate the iterated dominance frontier of BB.
+  const MachineDominanceFrontier::DomSetType &DF = DFLoc->second;
+  SetVector<MachineBasicBlock*> IDF(DF.begin(), DF.end());
+  for (unsigned i = 0; i < IDF.size(); ++i) {
+    auto F = MDF.find(IDF[i]);
+    if (F != MDF.end())
+      IDF.insert(F->second.begin(), F->second.end());
+  }
+
+  // Get the register references that are reachable from this block.
+  RegisterSet &Refs = RefM[BA.Id];
+  for (auto DB : IDF) {
+    NodeAddr<BlockNode*> DBA = findBlock(DB);
+    const RegisterSet &RefsD = RefM[DBA.Id];
+    Refs.insert(RefsD.begin(), RefsD.end());
+  }
+
+  // Finally, add the set of defs to each block in the iterated dominance
+  // frontier.
+  for (auto DB : IDF) {
+    NodeAddr<BlockNode*> DBA = findBlock(DB);
+    PhiM[DBA.Id].insert(Defs.begin(), Defs.end());
+  }
+}
+
+// Given the locations of phi nodes in the map PhiM, create the phi nodes
+// that are located in the block node BA.
+void DataFlowGraph::buildPhis(BlockRefsMap &PhiM, BlockRefsMap &RefM,
+      NodeAddr<BlockNode*> BA) {
+  // Check if this blocks has any DF defs, i.e. if there are any defs
+  // that this block is in the iterated dominance frontier of.
+  auto HasDF = PhiM.find(BA.Id);
+  if (HasDF == PhiM.end() || HasDF->second.empty())
+    return;
+
+  // First, remove all R in Refs in such that there exists T in Refs
+  // such that T covers R. In other words, only leave those refs that
+  // are not covered by another ref (i.e. maximal with respect to covering).
+
+  auto MaxCoverIn = [this] (RegisterRef RR, RegisterSet &RRs) -> RegisterRef {
+    for (RegisterRef I : RRs)
+      if (I != RR && RegisterAggr::isCoverOf(I, RR, PRI))
+        RR = I;
+    return RR;
+  };
+
+  RegisterSet MaxDF;
+  for (RegisterRef I : HasDF->second)
+    MaxDF.insert(MaxCoverIn(I, HasDF->second));
+
+  std::vector<RegisterRef> MaxRefs;
+  RegisterSet &RefB = RefM[BA.Id];
+  for (RegisterRef I : MaxDF)
+    MaxRefs.push_back(MaxCoverIn(I, RefB));
+
+  // Now, for each R in MaxRefs, get the alias closure of R. If the closure
+  // only has R in it, create a phi a def for R. Otherwise, create a phi,
+  // and add a def for each S in the closure.
+
+  // Sort the refs so that the phis will be created in a deterministic order.
+  std::sort(MaxRefs.begin(), MaxRefs.end());
+  // Remove duplicates.
+  auto NewEnd = std::unique(MaxRefs.begin(), MaxRefs.end());
+  MaxRefs.erase(NewEnd, MaxRefs.end());
+
+  auto Aliased = [this,&MaxRefs](RegisterRef RR,
+                                 std::vector<unsigned> &Closure) -> bool {
+    for (unsigned I : Closure)
+      if (PRI.alias(RR, MaxRefs[I]))
+        return true;
+    return false;
+  };
+
+  // Prepare a list of NodeIds of the block's predecessors.
+  NodeList Preds;
+  const MachineBasicBlock *MBB = BA.Addr->getCode();
+  for (MachineBasicBlock *PB : MBB->predecessors())
+    Preds.push_back(findBlock(PB));
+
+  while (!MaxRefs.empty()) {
+    // Put the first element in the closure, and then add all subsequent
+    // elements from MaxRefs to it, if they alias at least one element
+    // already in the closure.
+    // ClosureIdx: vector of indices in MaxRefs of members of the closure.
+    std::vector<unsigned> ClosureIdx = { 0 };
+    for (unsigned i = 1; i != MaxRefs.size(); ++i)
+      if (Aliased(MaxRefs[i], ClosureIdx))
+        ClosureIdx.push_back(i);
+
+    // Build a phi for the closure.
+    unsigned CS = ClosureIdx.size();
+    NodeAddr<PhiNode*> PA = newPhi(BA);
+
+    // Add defs.
+    for (unsigned X = 0; X != CS; ++X) {
+      RegisterRef RR = MaxRefs[ClosureIdx[X]];
+      uint16_t PhiFlags = NodeAttrs::PhiRef | NodeAttrs::Preserving;
+      NodeAddr<DefNode*> DA = newDef(PA, RR, PhiFlags);
+      PA.Addr->addMember(DA, *this);
+    }
+    // Add phi uses.
+    for (NodeAddr<BlockNode*> PBA : Preds) {
+      for (unsigned X = 0; X != CS; ++X) {
+        RegisterRef RR = MaxRefs[ClosureIdx[X]];
+        NodeAddr<PhiUseNode*> PUA = newPhiUse(PA, RR, PBA);
+        PA.Addr->addMember(PUA, *this);
+      }
+    }
+
+    // Erase from MaxRefs all elements in the closure.
+    auto Begin = MaxRefs.begin();
+    for (unsigned i = ClosureIdx.size(); i != 0; --i)
+      MaxRefs.erase(Begin + ClosureIdx[i-1]);
+  }
+}
+
+// Remove any unneeded phi nodes that were created during the build process.
+void DataFlowGraph::removeUnusedPhis() {
+  // This will remove unused phis, i.e. phis where each def does not reach
+  // any uses or other defs. This will not detect or remove circular phi
+  // chains that are otherwise dead. Unused/dead phis are created during
+  // the build process and this function is intended to remove these cases
+  // that are easily determinable to be unnecessary.
+
+  SetVector<NodeId> PhiQ;
+  for (NodeAddr<BlockNode*> BA : Func.Addr->members(*this)) {
+    for (auto P : BA.Addr->members_if(IsPhi, *this))
+      PhiQ.insert(P.Id);
+  }
+
+  static auto HasUsedDef = [](NodeList &Ms) -> bool {
+    for (NodeAddr<NodeBase*> M : Ms) {
+      if (M.Addr->getKind() != NodeAttrs::Def)
+        continue;
+      NodeAddr<DefNode*> DA = M;
+      if (DA.Addr->getReachedDef() != 0 || DA.Addr->getReachedUse() != 0)
+        return true;
+    }
+    return false;
+  };
+
+  // Any phi, if it is removed, may affect other phis (make them dead).
+  // For each removed phi, collect the potentially affected phis and add
+  // them back to the queue.
+  while (!PhiQ.empty()) {
+    auto PA = addr<PhiNode*>(PhiQ[0]);
+    PhiQ.remove(PA.Id);
+    NodeList Refs = PA.Addr->members(*this);
+    if (HasUsedDef(Refs))
+      continue;
+    for (NodeAddr<RefNode*> RA : Refs) {
+      if (NodeId RD = RA.Addr->getReachingDef()) {
+        auto RDA = addr<DefNode*>(RD);
+        NodeAddr<InstrNode*> OA = RDA.Addr->getOwner(*this);
+        if (IsPhi(OA))
+          PhiQ.insert(OA.Id);
+      }
+      if (RA.Addr->isDef())
+        unlinkDef(RA, true);
+      else
+        unlinkUse(RA, true);
+    }
+    NodeAddr<BlockNode*> BA = PA.Addr->getOwner(*this);
+    BA.Addr->removeMember(PA, *this);
+  }
+}
+
+// For a given reference node TA in an instruction node IA, connect the
+// reaching def of TA to the appropriate def node. Create any shadow nodes
+// as appropriate.
+template <typename T>
+void DataFlowGraph::linkRefUp(NodeAddr<InstrNode*> IA, NodeAddr<T> TA,
+      DefStack &DS) {
+  if (DS.empty())
+    return;
+  RegisterRef RR = TA.Addr->getRegRef(*this);
+  NodeAddr<T> TAP;
+
+  // References from the def stack that have been examined so far.
+  RegisterAggr Defs(PRI);
+
+  for (auto I = DS.top(), E = DS.bottom(); I != E; I.down()) {
+    RegisterRef QR = I->Addr->getRegRef(*this);
+
+    // Skip all defs that are aliased to any of the defs that we have already
+    // seen. If this completes a cover of RR, stop the stack traversal.
+    bool Alias = Defs.hasAliasOf(QR);
+    bool Cover = Defs.insert(QR).hasCoverOf(RR);
+    if (Alias) {
+      if (Cover)
+        break;
+      continue;
+    }
+
+    // The reaching def.
+    NodeAddr<DefNode*> RDA = *I;
+
+    // Pick the reached node.
+    if (TAP.Id == 0) {
+      TAP = TA;
+    } else {
+      // Mark the existing ref as "shadow" and create a new shadow.
+      TAP.Addr->setFlags(TAP.Addr->getFlags() | NodeAttrs::Shadow);
+      TAP = getNextShadow(IA, TAP, true);
+    }
+
+    // Create the link.
+    TAP.Addr->linkToDef(TAP.Id, RDA);
+
+    if (Cover)
+      break;
+  }
+}
+
+// Create data-flow links for all reference nodes in the statement node SA.
+template <typename Predicate>
+void DataFlowGraph::linkStmtRefs(DefStackMap &DefM, NodeAddr<StmtNode*> SA,
+      Predicate P) {
+#ifndef NDEBUG
+  RegisterSet Defs;
+#endif
+
+  // Link all nodes (upwards in the data-flow) with their reaching defs.
+  for (NodeAddr<RefNode*> RA : SA.Addr->members_if(P, *this)) {
+    uint16_t Kind = RA.Addr->getKind();
+    assert(Kind == NodeAttrs::Def || Kind == NodeAttrs::Use);
+    RegisterRef RR = RA.Addr->getRegRef(*this);
+#ifndef NDEBUG
+    // Do not expect multiple defs of the same reference.
+    assert(Kind != NodeAttrs::Def || !Defs.count(RR));
+    Defs.insert(RR);
+#endif
+
+    auto F = DefM.find(RR.Reg);
+    if (F == DefM.end())
+      continue;
+    DefStack &DS = F->second;
+    if (Kind == NodeAttrs::Use)
+      linkRefUp<UseNode*>(SA, RA, DS);
+    else if (Kind == NodeAttrs::Def)
+      linkRefUp<DefNode*>(SA, RA, DS);
+    else
+      llvm_unreachable("Unexpected node in instruction");
+  }
+}
+
+// Create data-flow links for all instructions in the block node BA. This
+// will include updating any phi nodes in BA.
+void DataFlowGraph::linkBlockRefs(DefStackMap &DefM, NodeAddr<BlockNode*> BA) {
+  // Push block delimiters.
+  markBlock(BA.Id, DefM);
+
+  auto IsClobber = [] (NodeAddr<RefNode*> RA) -> bool {
+    return IsDef(RA) && (RA.Addr->getFlags() & NodeAttrs::Clobbering);
+  };
+  auto IsNoClobber = [] (NodeAddr<RefNode*> RA) -> bool {
+    return IsDef(RA) && !(RA.Addr->getFlags() & NodeAttrs::Clobbering);
+  };
+
+  assert(BA.Addr && "block node address is needed to create a data-flow link");
+  // For each non-phi instruction in the block, link all the defs and uses
+  // to their reaching defs. For any member of the block (including phis),
+  // push the defs on the corresponding stacks.
+  for (NodeAddr<InstrNode*> IA : BA.Addr->members(*this)) {
+    // Ignore phi nodes here. They will be linked part by part from the
+    // predecessors.
+    if (IA.Addr->getKind() == NodeAttrs::Stmt) {
+      linkStmtRefs(DefM, IA, IsUse);
+      linkStmtRefs(DefM, IA, IsClobber);
+    }
+
+    // Push the definitions on the stack.
+    pushClobbers(IA, DefM);
+
+    if (IA.Addr->getKind() == NodeAttrs::Stmt)
+      linkStmtRefs(DefM, IA, IsNoClobber);
+
+    pushDefs(IA, DefM);
+  }
+
+  // Recursively process all children in the dominator tree.
+  MachineDomTreeNode *N = MDT.getNode(BA.Addr->getCode());
+  for (auto I : *N) {
+    MachineBasicBlock *SB = I->getBlock();
+    NodeAddr<BlockNode*> SBA = findBlock(SB);
+    linkBlockRefs(DefM, SBA);
+  }
+
+  // Link the phi uses from the successor blocks.
+  auto IsUseForBA = [BA](NodeAddr<NodeBase*> NA) -> bool {
+    if (NA.Addr->getKind() != NodeAttrs::Use)
+      return false;
+    assert(NA.Addr->getFlags() & NodeAttrs::PhiRef);
+    NodeAddr<PhiUseNode*> PUA = NA;
+    return PUA.Addr->getPredecessor() == BA.Id;
+  };
+
+  RegisterSet EHLiveIns = getLandingPadLiveIns();
+  MachineBasicBlock *MBB = BA.Addr->getCode();
+
+  for (MachineBasicBlock *SB : MBB->successors()) {
+    bool IsEHPad = SB->isEHPad();
+    NodeAddr<BlockNode*> SBA = findBlock(SB);
+    for (NodeAddr<InstrNode*> IA : SBA.Addr->members_if(IsPhi, *this)) {
+      // Do not link phi uses for landing pad live-ins.
+      if (IsEHPad) {
+        // Find what register this phi is for.
+        NodeAddr<RefNode*> RA = IA.Addr->getFirstMember(*this);
+        assert(RA.Id != 0);
+        if (EHLiveIns.count(RA.Addr->getRegRef(*this)))
+          continue;
+      }
+      // Go over each phi use associated with MBB, and link it.
+      for (auto U : IA.Addr->members_if(IsUseForBA, *this)) {
+        NodeAddr<PhiUseNode*> PUA = U;
+        RegisterRef RR = PUA.Addr->getRegRef(*this);
+        linkRefUp<UseNode*>(IA, PUA, DefM[RR.Reg]);
+      }
+    }
+  }
+
+  // Pop all defs from this block from the definition stacks.
+  releaseBlock(BA.Id, DefM);
+}
+
+// Remove the use node UA from any data-flow and structural links.
+void DataFlowGraph::unlinkUseDF(NodeAddr<UseNode*> UA) {
+  NodeId RD = UA.Addr->getReachingDef();
+  NodeId Sib = UA.Addr->getSibling();
+
+  if (RD == 0) {
+    assert(Sib == 0);
+    return;
+  }
+
+  auto RDA = addr<DefNode*>(RD);
+  auto TA = addr<UseNode*>(RDA.Addr->getReachedUse());
+  if (TA.Id == UA.Id) {
+    RDA.Addr->setReachedUse(Sib);
+    return;
+  }
+
+  while (TA.Id != 0) {
+    NodeId S = TA.Addr->getSibling();
+    if (S == UA.Id) {
+      TA.Addr->setSibling(UA.Addr->getSibling());
+      return;
+    }
+    TA = addr<UseNode*>(S);
+  }
+}
+
+// Remove the def node DA from any data-flow and structural links.
+void DataFlowGraph::unlinkDefDF(NodeAddr<DefNode*> DA) {
+  //
+  //         RD
+  //         | reached
+  //         | def
+  //         :
+  //         .
+  //        +----+
+  // ... -- | DA | -- ... -- 0  : sibling chain of DA
+  //        +----+
+  //         |  | reached
+  //         |  : def
+  //         |  .
+  //         | ...  : Siblings (defs)
+  //         |
+  //         : reached
+  //         . use
+  //        ... : sibling chain of reached uses
+
+  NodeId RD = DA.Addr->getReachingDef();
+
+  // Visit all siblings of the reached def and reset their reaching defs.
+  // Also, defs reached by DA are now "promoted" to being reached by RD,
+  // so all of them will need to be spliced into the sibling chain where
+  // DA belongs.
+  auto getAllNodes = [this] (NodeId N) -> NodeList {
+    NodeList Res;
+    while (N) {
+      auto RA = addr<RefNode*>(N);
+      // Keep the nodes in the exact sibling order.
+      Res.push_back(RA);
+      N = RA.Addr->getSibling();
+    }
+    return Res;
+  };
+  NodeList ReachedDefs = getAllNodes(DA.Addr->getReachedDef());
+  NodeList ReachedUses = getAllNodes(DA.Addr->getReachedUse());
+
+  if (RD == 0) {
+    for (NodeAddr<RefNode*> I : ReachedDefs)
+      I.Addr->setSibling(0);
+    for (NodeAddr<RefNode*> I : ReachedUses)
+      I.Addr->setSibling(0);
+  }
+  for (NodeAddr<DefNode*> I : ReachedDefs)
+    I.Addr->setReachingDef(RD);
+  for (NodeAddr<UseNode*> I : ReachedUses)
+    I.Addr->setReachingDef(RD);
+
+  NodeId Sib = DA.Addr->getSibling();
+  if (RD == 0) {
+    assert(Sib == 0);
+    return;
+  }
+
+  // Update the reaching def node and remove DA from the sibling list.
+  auto RDA = addr<DefNode*>(RD);
+  auto TA = addr<DefNode*>(RDA.Addr->getReachedDef());
+  if (TA.Id == DA.Id) {
+    // If DA is the first reached def, just update the RD's reached def
+    // to the DA's sibling.
+    RDA.Addr->setReachedDef(Sib);
+  } else {
+    // Otherwise, traverse the sibling list of the reached defs and remove
+    // DA from it.
+    while (TA.Id != 0) {
+      NodeId S = TA.Addr->getSibling();
+      if (S == DA.Id) {
+        TA.Addr->setSibling(Sib);
+        break;
+      }
+      TA = addr<DefNode*>(S);
+    }
+  }
+
+  // Splice the DA's reached defs into the RDA's reached def chain.
+  if (!ReachedDefs.empty()) {
+    auto Last = NodeAddr<DefNode*>(ReachedDefs.back());
+    Last.Addr->setSibling(RDA.Addr->getReachedDef());
+    RDA.Addr->setReachedDef(ReachedDefs.front().Id);
+  }
+  // Splice the DA's reached uses into the RDA's reached use chain.
+  if (!ReachedUses.empty()) {
+    auto Last = NodeAddr<UseNode*>(ReachedUses.back());
+    Last.Addr->setSibling(RDA.Addr->getReachedUse());
+    RDA.Addr->setReachedUse(ReachedUses.front().Id);
+  }
+}

lib/CodeGen/RDFLiveness.cpp

+//===--- RDFLiveness.cpp --------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Computation of the liveness information from the data-flow graph.
+//
+// The main functionality of this code is to compute block live-in
+// information. With the live-in information in place, the placement
+// of kill flags can also be recalculated.
+//
+// The block live-in calculation is based on the ideas from the following
+// publication:
+//
+// Dibyendu Das, Ramakrishna Upadrasta, Benoit Dupont de Dinechin.
+// "Efficient Liveness Computation Using Merge Sets and DJ-Graphs."
+// ACM Transactions on Architecture and Code Optimization, Association for
+// Computing Machinery, 2012, ACM TACO Special Issue on "High-Performance
+// and Embedded Architectures and Compilers", 8 (4),
+// <10.1145/2086696.2086706>. <hal-00647369>
+//
+#include "llvm/ADT/SetVector.h"
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineDominanceFrontier.h"
+#include "llvm/CodeGen/MachineDominators.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/RDFGraph.h"
+#include "llvm/CodeGen/RDFLiveness.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+
+using namespace llvm;
+using namespace rdf;
+
+static cl::opt<unsigned> MaxRecNest("rdf-liveness-max-rec", cl::init(25),
+  cl::Hidden, cl::desc("Maximum recursion level"));
+
+namespace llvm {
+namespace rdf {
+  template<>
+  raw_ostream &operator<< (raw_ostream &OS, const Print<Liveness::RefMap> &P) {
+    OS << '{';
+    for (auto &I : P.Obj) {
+      OS << ' ' << PrintReg(I.first, &P.G.getTRI()) << '{';
+      for (auto J = I.second.begin(), E = I.second.end(); J != E; ) {
+        OS << Print<NodeId>(J->first, P.G) << PrintLaneMaskOpt(J->second);
+        if (++J != E)
+          OS << ',';
+      }
+      OS << '}';
+    }
+    OS << " }";
+    return OS;
+  }
+} // namespace rdf
+} // namespace llvm
+
+// The order in the returned sequence is the order of reaching defs in the
+// upward traversal: the first def is the closest to the given reference RefA,
+// the next one is further up, and so on.
+// The list ends at a reaching phi def, or when the reference from RefA is
+// covered by the defs in the list (see FullChain).
+// This function provides two modes of operation:
+// (1) Returning the sequence of reaching defs for a particular reference
+// node. This sequence will terminate at the first phi node [1].
+// (2) Returning a partial sequence of reaching defs, where the final goal
+// is to traverse past phi nodes to the actual defs arising from the code
+// itself.
+// In mode (2), the register reference for which the search was started
+// may be different from the reference node RefA, for which this call was
+// made, hence the argument RefRR, which holds the original register.
+// Also, some definitions may have already been encountered in a previous
+// call that will influence register covering. The register references
+// already defined are passed in through DefRRs.
+// In mode (1), the "continuation" considerations do not apply, and the
+// RefRR is the same as the register in RefA, and the set DefRRs is empty.
+//
+// [1] It is possible for multiple phi nodes to be included in the returned
+// sequence:
+//   SubA = phi ...
+//   SubB = phi ...
+//   ...  = SuperAB(rdef:SubA), SuperAB"(rdef:SubB)
+// However, these phi nodes are independent from one another in terms of
+// the data-flow.
+
+NodeList Liveness::getAllReachingDefs(RegisterRef RefRR,
+      NodeAddr<RefNode*> RefA, bool TopShadows, bool FullChain,
+      const RegisterAggr &DefRRs) {
+  NodeList RDefs; // Return value.
+  SetVector<NodeId> DefQ;
+  SetVector<NodeId> Owners;
+
+  // Dead defs will be treated as if they were live, since they are actually
+  // on the data-flow path. They cannot be ignored because even though they
+  // do not generate meaningful values, they still modify registers.
+
+  // If the reference is undefined, there is nothing to do.
+  if (RefA.Addr->getFlags() & NodeAttrs::Undef)
+    return RDefs;
+
+  // The initial queue should not have reaching defs for shadows. The
+  // whole point of a shadow is that it will have a reaching def that
+  // is not aliased to the reaching defs of the related shadows.
+  NodeId Start = RefA.Id;
+  auto SNA = DFG.addr<RefNode*>(Start);
+  if (NodeId RD = SNA.Addr->getReachingDef())
+    DefQ.insert(RD);
+  if (TopShadows) {
+    for (auto S : DFG.getRelatedRefs(RefA.Addr->getOwner(DFG), RefA))
+      if (NodeId RD = NodeAddr<RefNode*>(S).Addr->getReachingDef())
+        DefQ.insert(RD);
+  }
+
+  // Collect all the reaching defs, going up until a phi node is encountered,
+  // or there are no more reaching defs. From this set, the actual set of
+  // reaching defs will be selected.
+  // The traversal upwards must go on until a covering def is encountered.
+  // It is possible that a collection of non-covering (individually) defs
+  // will be sufficient, but keep going until a covering one is found.
+  for (unsigned i = 0; i < DefQ.size(); ++i) {
+    auto TA = DFG.addr<DefNode*>(DefQ[i]);
+    if (TA.Addr->getFlags() & NodeAttrs::PhiRef)
+      continue;
+    // Stop at the covering/overwriting def of the initial register reference.
+    RegisterRef RR = TA.Addr->getRegRef(DFG);
+    if (!DFG.IsPreservingDef(TA))
+      if (RegisterAggr::isCoverOf(RR, RefRR, PRI))
+        continue;
+    // Get the next level of reaching defs. This will include multiple
+    // reaching defs for shadows.
+    for (auto S : DFG.getRelatedRefs(TA.Addr->getOwner(DFG), TA))
+      if (NodeId RD = NodeAddr<RefNode*>(S).Addr->getReachingDef())
+        DefQ.insert(RD);
+  }
+
+  // Remove all non-phi defs that are not aliased to RefRR, and collect
+  // the owners of the remaining defs.
+  SetVector<NodeId> Defs;
+  for (NodeId N : DefQ) {
+    auto TA = DFG.addr<DefNode*>(N);
+    bool IsPhi = TA.Addr->getFlags() & NodeAttrs::PhiRef;
+    if (!IsPhi && !PRI.alias(RefRR, TA.Addr->getRegRef(DFG)))
+      continue;
+    Defs.insert(TA.Id);
+    Owners.insert(TA.Addr->getOwner(DFG).Id);
+  }
+
+  // Return the MachineBasicBlock containing a given instruction.
+  auto Block = [this] (NodeAddr<InstrNode*> IA) -> MachineBasicBlock* {
+    if (IA.Addr->getKind() == NodeAttrs::Stmt)
+      return NodeAddr<StmtNode*>(IA).Addr->getCode()->getParent();
+    assert(IA.Addr->getKind() == NodeAttrs::Phi);
+    NodeAddr<PhiNode*> PA = IA;
+    NodeAddr<BlockNode*> BA = PA.Addr->getOwner(DFG);
+    return BA.Addr->getCode();
+  };
+  // Less(A,B) iff instruction A is further down in the dominator tree than B.
+  auto Less = [&Block,this] (NodeId A, NodeId B) -> bool {
+    if (A == B)
+      return false;
+    auto OA = DFG.addr<InstrNode*>(A), OB = DFG.addr<InstrNode*>(B);
+    MachineBasicBlock *BA = Block(OA), *BB = Block(OB);
+    if (BA != BB)
+      return MDT.dominates(BB, BA);
+    // They are in the same block.
+    bool StmtA = OA.Addr->getKind() == NodeAttrs::Stmt;
+    bool StmtB = OB.Addr->getKind() == NodeAttrs::Stmt;
+    if (StmtA) {
+      if (!StmtB)   // OB is a phi and phis dominate statements.
+        return true;
+      MachineInstr *CA = NodeAddr<StmtNode*>(OA).Addr->getCode();
+      MachineInstr *CB = NodeAddr<StmtNode*>(OB).Addr->getCode();
+      // The order must be linear, so tie-break such equalities.
+      if (CA == CB)
+        return A < B;
+      return MDT.dominates(CB, CA);
+    } else {
+      // OA is a phi.
+      if (StmtB)
+        return false;
+      // Both are phis. There is no ordering between phis (in terms of
+      // the data-flow), so tie-break this via node id comparison.
+      return A < B;
+    }
+  };
+
+  std::vector<NodeId> Tmp(Owners.begin(), Owners.end());
+  std::sort(Tmp.begin(), Tmp.end(), Less);
+
+  // The vector is a list of instructions, so that defs coming from
+  // the same instruction don't need to be artificially ordered.
+  // Then, when computing the initial segment, and iterating over an
+  // instruction, pick the defs that contribute to the covering (i.e. is
+  // not covered by previously added defs). Check the defs individually,
+  // i.e. first check each def if is covered or not (without adding them
+  // to the tracking set), and then add all the selected ones.
+
+  // The reason for this is this example:
+  // *d1<A>, *d2<B>, ... Assume A and B are aliased (can happen in phi nodes).
+  // *d3<C>              If A \incl BuC, and B \incl AuC, then *d2 would be
+  //                     covered if we added A first, and A would be covered
+  //                     if we added B first.
+
+  RegisterAggr RRs(DefRRs);
+
+  auto DefInSet = [&Defs] (NodeAddr<RefNode*> TA) -> bool {
+    return TA.Addr->getKind() == NodeAttrs::Def &&
+           Defs.count(TA.Id);
+  };
+  for (NodeId T : Tmp) {
+    if (!FullChain && RRs.hasCoverOf(RefRR))
+      break;
+    auto TA = DFG.addr<InstrNode*>(T);
+    bool IsPhi = DFG.IsCode<NodeAttrs::Phi>(TA);
+    NodeList Ds;
+    for (NodeAddr<DefNode*> DA : TA.Addr->members_if(DefInSet, DFG)) {
+      RegisterRef QR = DA.Addr->getRegRef(DFG);
+      // Add phi defs even if they are covered by subsequent defs. This is
+      // for cases where the reached use is not covered by any of the defs
+      // encountered so far: the phi def is needed to expose the liveness
+      // of that use to the entry of the block.
+      // Example:
+      //   phi d1<R3>(,d2,), ...  Phi def d1 is covered by d2.
+      //   d2<R3>(d1,,u3), ...
+      //   ..., u3<D1>(d2)        This use needs to be live on entry.
+      if (FullChain || IsPhi || !RRs.hasCoverOf(QR))
+        Ds.push_back(DA);
+    }
+    RDefs.insert(RDefs.end(), Ds.begin(), Ds.end());
+    for (NodeAddr<DefNode*> DA : Ds) {
+      // When collecting a full chain of definitions, do not consider phi
+      // defs to actually define a register.
+      uint16_t Flags = DA.Addr->getFlags();
+      if (!FullChain || !(Flags & NodeAttrs::PhiRef))
+        if (!(Flags & NodeAttrs::Preserving)) // Don't care about Undef here.
+          RRs.insert(DA.Addr->getRegRef(DFG));
+    }
+  }
+
+  auto DeadP = [](const NodeAddr<DefNode*> DA) -> bool {
+    return DA.Addr->getFlags() & NodeAttrs::Dead;
+  };
+  RDefs.resize(std::distance(RDefs.begin(), remove_if(RDefs, DeadP)));
+
+  return RDefs;
+}
+
+
+std::pair<NodeSet,bool>
+Liveness::getAllReachingDefsRec(RegisterRef RefRR, NodeAddr<RefNode*> RefA,
+      NodeSet &Visited, const NodeSet &Defs) {
+  return getAllReachingDefsRecImpl(RefRR, RefA, Visited, Defs, 0, MaxRecNest);
+}
+
+
+std::pair<NodeSet,bool>
+Liveness::getAllReachingDefsRecImpl(RegisterRef RefRR, NodeAddr<RefNode*> RefA,
+      NodeSet &Visited, const NodeSet &Defs, unsigned Nest, unsigned MaxNest) {
+  if (Nest > MaxNest)
+    return { NodeSet(), false };
+  // Collect all defined registers. Do not consider phis to be defining
+  // anything, only collect "real" definitions.
+  RegisterAggr DefRRs(PRI);
+  for (NodeId D : Defs) {
+    const auto DA = DFG.addr<const DefNode*>(D);
+    if (!(DA.Addr->getFlags() & NodeAttrs::PhiRef))
+      DefRRs.insert(DA.Addr->getRegRef(DFG));
+  }
+
+  NodeList RDs = getAllReachingDefs(RefRR, RefA, false, true, DefRRs);
+  if (RDs.empty())
+    return { Defs, true };
+
+  // Make a copy of the preexisting definitions and add the newly found ones.
+  NodeSet TmpDefs = Defs;
+  for (NodeAddr<NodeBase*> R : RDs)
+    TmpDefs.insert(R.Id);
+
+  NodeSet Result = Defs;
+
+  for (NodeAddr<DefNode*> DA : RDs) {
+    Result.insert(DA.Id);
+    if (!(DA.Addr->getFlags() & NodeAttrs::PhiRef))
+      continue;
+    NodeAddr<PhiNode*> PA = DA.Addr->getOwner(DFG);
+    if (Visited.count(PA.Id))
+      continue;
+    Visited.insert(PA.Id);
+    // Go over all phi uses and get the reaching defs for each use.
+    for (auto U : PA.Addr->members_if(DFG.IsRef<NodeAttrs::Use>, DFG)) {
+      const auto &T = getAllReachingDefsRecImpl(RefRR, U, Visited, TmpDefs,
+                                                Nest+1, MaxNest);
+      if (!T.second)
+        return { T.first, false };
+      Result.insert(T.first.begin(), T.first.end());
+    }
+  }
+
+  return { Result, true };
+}
+
+/// Find the nearest ref node aliased to RefRR, going upwards in the data
+/// flow, starting from the instruction immediately preceding Inst.
+NodeAddr<RefNode*> Liveness::getNearestAliasedRef(RegisterRef RefRR,
+      NodeAddr<InstrNode*> IA) {
+  NodeAddr<BlockNode*> BA = IA.Addr->getOwner(DFG);
+  NodeList Ins = BA.Addr->members(DFG);
+  NodeId FindId = IA.Id;
+  auto E = Ins.rend();
+  auto B = std::find_if(Ins.rbegin(), E,
+                        [FindId] (const NodeAddr<InstrNode*> T) {
+                          return T.Id == FindId;
+                        });
+  // Do not scan IA (which is what B would point to).
+  if (B != E)
+    ++B;
+
+  do {
+    // Process the range of instructions from B to E.
+    for (NodeAddr<InstrNode*> I : make_range(B, E)) {
+      NodeList Refs = I.Addr->members(DFG);
+      NodeAddr<RefNode*> Clob, Use;
+      // Scan all the refs in I aliased to RefRR, and return the one that
+      // is the closest to the output of I, i.e. def > clobber > use.
+      for (NodeAddr<RefNode*> R : Refs) {
+        if (!PRI.alias(R.Addr->getRegRef(DFG), RefRR))
+          continue;
+        if (DFG.IsDef(R)) {
+          // If it's a non-clobbering def, just return it.
+          if (!(R.Addr->getFlags() & NodeAttrs::Clobbering))
+            return R;
+          Clob = R;
+        } else {
+          Use = R;
+        }
+      }
+      if (Clob.Id != 0)
+        return Clob;
+      if (Use.Id != 0)
+        return Use;
+    }
+
+    // Go up to the immediate dominator, if any.
+    MachineBasicBlock *BB = BA.Addr->getCode();
+    BA = NodeAddr<BlockNode*>();
+    if (MachineDomTreeNode *N = MDT.getNode(BB)) {
+      if ((N = N->getIDom()))
+        BA = DFG.findBlock(N->getBlock());
+    }
+    if (!BA.Id)
+      break;
+
+    Ins = BA.Addr->members(DFG);
+    B = Ins.rbegin();
+    E = Ins.rend();
+  } while (true);
+
+  return NodeAddr<RefNode*>();
+}
+
+
+NodeSet Liveness::getAllReachedUses(RegisterRef RefRR,
+      NodeAddr<DefNode*> DefA, const RegisterAggr &DefRRs) {
+  NodeSet Uses;
+
+  // If the original register is already covered by all the intervening
+  // defs, no more uses can be reached.
+  if (DefRRs.hasCoverOf(RefRR))
+    return Uses;
+
+  // Add all directly reached uses.
+  // If the def is dead, it does not provide a value for any use.
+  bool IsDead = DefA.Addr->getFlags() & NodeAttrs::Dead;
+  NodeId U = !IsDead ? DefA.Addr->getReachedUse() : 0;
+  while (U != 0) {
+    auto UA = DFG.addr<UseNode*>(U);
+    if (!(UA.Addr->getFlags() & NodeAttrs::Undef)) {
+      RegisterRef UR = UA.Addr->getRegRef(DFG);
+      if (PRI.alias(RefRR, UR) && !DefRRs.hasCoverOf(UR))
+        Uses.insert(U);
+    }
+    U = UA.Addr->getSibling();
+  }
+
+  // Traverse all reached defs. This time dead defs cannot be ignored.
+  for (NodeId D = DefA.Addr->getReachedDef(), NextD; D != 0; D = NextD) {
+    auto DA = DFG.addr<DefNode*>(D);
+    NextD = DA.Addr->getSibling();
+    RegisterRef DR = DA.Addr->getRegRef(DFG);
+    // If this def is already covered, it cannot reach anything new.
+    // Similarly, skip it if it is not aliased to the interesting register.
+    if (DefRRs.hasCoverOf(DR) || !PRI.alias(RefRR, DR))
+      continue;
+    NodeSet T;
+    if (DFG.IsPreservingDef(DA)) {
+      // If it is a preserving def, do not update the set of intervening defs.
+      T = getAllReachedUses(RefRR, DA, DefRRs);
+    } else {
+      RegisterAggr NewDefRRs = DefRRs;
+      NewDefRRs.insert(DR);
+      T = getAllReachedUses(RefRR, DA, NewDefRRs);
+    }
+    Uses.insert(T.begin(), T.end());
+  }
+  return Uses;
+}
+
+
+void Liveness::computePhiInfo() {
+  RealUseMap.clear();
+
+  NodeList Phis;
+  NodeAddr<FuncNode*> FA = DFG.getFunc();
+  NodeList Blocks = FA.Addr->members(DFG);
+  for (NodeAddr<BlockNode*> BA : Blocks) {
+    auto Ps = BA.Addr->members_if(DFG.IsCode<NodeAttrs::Phi>, DFG);
+    Phis.insert(Phis.end(), Ps.begin(), Ps.end());
+  }
+
+  // phi use -> (map: reaching phi -> set of registers defined in between)
+  std::map<NodeId,std::map<NodeId,RegisterAggr>> PhiUp;
+  std::vector<NodeId> PhiUQ;  // Work list of phis for upward propagation.
+  std::map<NodeId,RegisterAggr> PhiDRs;  // Phi -> registers defined by it.
+
+  // Go over all phis.
+  for (NodeAddr<PhiNode*> PhiA : Phis) {
+    // Go over all defs and collect the reached uses that are non-phi uses
+    // (i.e. the "real uses").
+    RefMap &RealUses = RealUseMap[PhiA.Id];
+    NodeList PhiRefs = PhiA.Addr->members(DFG);
+
+    // Have a work queue of defs whose reached uses need to be found.
+    // For each def, add to the queue all reached (non-phi) defs.
+    SetVector<NodeId> DefQ;
+    NodeSet PhiDefs;
+    RegisterAggr DRs(PRI);
+    for (NodeAddr<RefNode*> R : PhiRefs) {
+      if (!DFG.IsRef<NodeAttrs::Def>(R))
+        continue;
+      DRs.insert(R.Addr->getRegRef(DFG));
+      DefQ.insert(R.Id);
+      PhiDefs.insert(R.Id);
+    }
+    PhiDRs.insert(std::make_pair(PhiA.Id, DRs));
+
+    // Collect the super-set of all possible reached uses. This set will
+    // contain all uses reached from this phi, either directly from the
+    // phi defs, or (recursively) via non-phi defs reached by the phi defs.
+    // This set of uses will later be trimmed to only contain these uses that
+    // are actually reached by the phi defs.
+    for (unsigned i = 0; i < DefQ.size(); ++i) {
+      NodeAddr<DefNode*> DA = DFG.addr<DefNode*>(DefQ[i]);
+      // Visit all reached uses. Phi defs should not really have the "dead"
+      // flag set, but check it anyway for consistency.
+      bool IsDead = DA.Addr->getFlags() & NodeAttrs::Dead;
+      NodeId UN = !IsDead ? DA.Addr->getReachedUse() : 0;
+      while (UN != 0) {
+        NodeAddr<UseNode*> A = DFG.addr<UseNode*>(UN);
+        uint16_t F = A.Addr->getFlags();
+        if ((F & (NodeAttrs::Undef | NodeAttrs::PhiRef)) == 0) {
+          RegisterRef R = PRI.normalize(A.Addr->getRegRef(DFG));
+          RealUses[R.Reg].insert({A.Id,R.Mask});
+        }
+        UN = A.Addr->getSibling();
+      }
+      // Visit all reached defs, and add them to the queue. These defs may
+      // override some of the uses collected here, but that will be handled
+      // later.
+      NodeId DN = DA.Addr->getReachedDef();
+      while (DN != 0) {
+        NodeAddr<DefNode*> A = DFG.addr<DefNode*>(DN);
+        for (auto T : DFG.getRelatedRefs(A.Addr->getOwner(DFG), A)) {
+          uint16_t Flags = NodeAddr<DefNode*>(T).Addr->getFlags();
+          // Must traverse the reached-def chain. Consider:
+          //   def(D0) -> def(R0) -> def(R0) -> use(D0)
+          // The reachable use of D0 passes through a def of R0.
+          if (!(Flags & NodeAttrs::PhiRef))
+            DefQ.insert(T.Id);
+        }
+        DN = A.Addr->getSibling();
+      }
+    }
+    // Filter out these uses that appear to be reachable, but really
+    // are not. For example:
+    //
+    // R1:0 =          d1
+    //      = R1:0     u2     Reached by d1.
+    //   R0 =          d3
+    //      = R1:0     u4     Still reached by d1: indirectly through
+    //                        the def d3.
+    //   R1 =          d5
+    //      = R1:0     u6     Not reached by d1 (covered collectively
+    //                        by d3 and d5), but following reached
+    //                        defs and uses from d1 will lead here.
+    auto InPhiDefs = [&PhiDefs] (NodeAddr<DefNode*> DA) -> bool {
+      return PhiDefs.count(DA.Id);
+    };
+    for (auto UI = RealUses.begin(), UE = RealUses.end(); UI != UE; ) {
+      // For each reached register UI->first, there is a set UI->second, of
+      // uses of it. For each such use, check if it is reached by this phi,
+      // i.e. check if the set of its reaching uses intersects the set of
+      // this phi's defs.
+      NodeRefSet &Uses = UI->second;
+      for (auto I = Uses.begin(), E = Uses.end(); I != E; ) {
+        auto UA = DFG.addr<UseNode*>(I->first);
+        // Undef flag is checked above.
+        assert((UA.Addr->getFlags() & NodeAttrs::Undef) == 0);
+        RegisterRef R(UI->first, I->second);
+        NodeList RDs = getAllReachingDefs(R, UA);
+        // If none of the reaching defs of R are from this phi, remove this
+        // use of R.
+        I = any_of(RDs, InPhiDefs) ? std::next(I) : Uses.erase(I);
+      }
+      UI = Uses.empty() ? RealUses.erase(UI) : std::next(UI);
+    }
+
+    // If this phi reaches some "real" uses, add it to the queue for upward
+    // propagation.
+    if (!RealUses.empty())
+      PhiUQ.push_back(PhiA.Id);
+
+    // Go over all phi uses and check if the reaching def is another phi.
+    // Collect the phis that are among the reaching defs of these uses.
+    // While traversing the list of reaching defs for each phi use, accumulate
+    // the set of registers defined between this phi (PhiA) and the owner phi
+    // of the reaching def.
+    NodeSet SeenUses;
+
+    for (auto I : PhiRefs) {
+      if (!DFG.IsRef<NodeAttrs::Use>(I) || SeenUses.count(I.Id))
+        continue;
+      NodeAddr<PhiUseNode*> PUA = I;
+      if (PUA.Addr->getReachingDef() == 0)
+        continue;
+
+      RegisterRef UR = PUA.Addr->getRegRef(DFG);
+      NodeList Ds = getAllReachingDefs(UR, PUA, true, false, NoRegs);
+      RegisterAggr DefRRs(PRI);
+
+      for (NodeAddr<DefNode*> D : Ds) {
+        if (D.Addr->getFlags() & NodeAttrs::PhiRef) {
+          NodeId RP = D.Addr->getOwner(DFG).Id;
+          std::map<NodeId,RegisterAggr> &M = PhiUp[PUA.Id];
+          auto F = M.find(RP);
+          if (F == M.end())
+            M.insert(std::make_pair(RP, DefRRs));
+          else
+            F->second.insert(DefRRs);
+        }
+        DefRRs.insert(D.Addr->getRegRef(DFG));
+      }
+
+      for (NodeAddr<PhiUseNode*> T : DFG.getRelatedRefs(PhiA, PUA))
+        SeenUses.insert(T.Id);
+    }
+  }
+
+  if (Trace) {
+    dbgs() << "Phi-up-to-phi map with intervening defs:\n";
+    for (auto I : PhiUp) {
+      dbgs() << "phi " << Print<NodeId>(I.first, DFG) << " -> {";
+      for (auto R : I.second)
+        dbgs() << ' ' << Print<NodeId>(R.first, DFG)
+               << Print<RegisterAggr>(R.second, DFG);
+      dbgs() << " }\n";
+    }
+  }
+
+  // Propagate the reached registers up in the phi chain.
+  //
+  // The following type of situation needs careful handling:
+  //
+  //   phi d1<R1:0>  (1)
+  //        |
+  //   ... d2<R1>
+  //        |
+  //   phi u3<R1:0>  (2)
+  //        |
+  //   ... u4<R1>
+  //
+  // The phi node (2) defines a register pair R1:0, and reaches a "real"
+  // use u4 of just R1. The same phi node is also known to reach (upwards)
+  // the phi node (1). However, the use u4 is not reached by phi (1),
+  // because of the intervening definition d2 of R1. The data flow between
+  // phis (1) and (2) is restricted to R1:0 minus R1, i.e. R0.
+  //
+  // When propagating uses up the phi chains, get the all reaching defs
+  // for a given phi use, and traverse the list until the propagated ref
+  // is covered, or until reaching the final phi. Only assume that the
+  // reference reaches the phi in the latter case.
+
+  for (unsigned i = 0; i < PhiUQ.size(); ++i) {
+    auto PA = DFG.addr<PhiNode*>(PhiUQ[i]);
+    NodeList PUs = PA.Addr->members_if(DFG.IsRef<NodeAttrs::Use>, DFG);
+    RefMap &RUM = RealUseMap[PA.Id];
+
+    for (NodeAddr<UseNode*> UA : PUs) {
+      std::map<NodeId,RegisterAggr> &PUM = PhiUp[UA.Id];
+      RegisterRef UR = PRI.normalize(UA.Addr->getRegRef(DFG));
+      for (const std::pair<NodeId,RegisterAggr> &P : PUM) {
+        bool Changed = false;
+        const RegisterAggr &MidDefs = P.second;
+
+        // Collect the set PropUp of uses that are reached by the current
+        // phi PA, and are not covered by any intervening def between the
+        // currently visited use UA and the the upward phi P.
+
+        if (MidDefs.hasCoverOf(UR))
+          continue;
+
+        // General algorithm:
+        //   for each (R,U) : U is use node of R, U is reached by PA
+        //     if MidDefs does not cover (R,U)
+        //       then add (R-MidDefs,U) to RealUseMap[P]
+        //
+        for (const std::pair<RegisterId,NodeRefSet> &T : RUM) {
+          RegisterRef R(T.first);
+          // The current phi (PA) could be a phi for a regmask. It could
+          // reach a whole variety of uses that are not related to the
+          // specific upward phi (P.first).
+          const RegisterAggr &DRs = PhiDRs.at(P.first);
+          if (!DRs.hasAliasOf(R))
+            continue;
+          R = DRs.intersectWith(R);
+          for (std::pair<NodeId,LaneBitmask> V : T.second) {
+            LaneBitmask M = R.Mask & V.second;
+            if (M.none())
+              continue;
+            if (RegisterRef SS = MidDefs.clearIn(RegisterRef(R.Reg, M))) {
+              NodeRefSet &RS = RealUseMap[P.first][SS.Reg];
+              Changed |= RS.insert({V.first,SS.Mask}).second;
+            }
+          }
+        }
+
+        if (Changed)
+          PhiUQ.push_back(P.first);
+      }
+    }
+  }
+
+  if (Trace) {
+    dbgs() << "Real use map:\n";
+    for (auto I : RealUseMap) {
+      dbgs() << "phi " << Print<NodeId>(I.first, DFG);
+      NodeAddr<PhiNode*> PA = DFG.addr<PhiNode*>(I.first);
+      NodeList Ds = PA.Addr->members_if(DFG.IsRef<NodeAttrs::Def>, DFG);
+      if (!Ds.empty()) {
+        RegisterRef RR = NodeAddr<DefNode*>(Ds[0]).Addr->getRegRef(DFG);
+        dbgs() << '<' << Print<RegisterRef>(RR, DFG) << '>';
+      } else {
+        dbgs() << "<noreg>";
+      }
+      dbgs() << " -> " << Print<RefMap>(I.second, DFG) << '\n';
+    }
+  }
+}
+
+
+void Liveness::computeLiveIns() {
+  // Populate the node-to-block map. This speeds up the calculations
+  // significantly.
+  NBMap.clear();
+  for (NodeAddr<BlockNode*> BA : DFG.getFunc().Addr->members(DFG)) {
+    MachineBasicBlock *BB = BA.Addr->getCode();
+    for (NodeAddr<InstrNode*> IA : BA.Addr->members(DFG)) {
+      for (NodeAddr<RefNode*> RA : IA.Addr->members(DFG))
+        NBMap.insert(std::make_pair(RA.Id, BB));
+      NBMap.insert(std::make_pair(IA.Id, BB));
+    }
+  }
+
+  MachineFunction &MF = DFG.getMF();
+
+  // Compute IDF first, then the inverse.
+  decltype(IIDF) IDF;
+  for (MachineBasicBlock &B : MF) {
+    auto F1 = MDF.find(&B);
+    if (F1 == MDF.end())
+      continue;
+    SetVector<MachineBasicBlock*> IDFB(F1->second.begin(), F1->second.end());
+    for (unsigned i = 0; i < IDFB.size(); ++i) {
+      auto F2 = MDF.find(IDFB[i]);
+      if (F2 != MDF.end())
+        IDFB.insert(F2->second.begin(), F2->second.end());
+    }
+    // Add B to the IDF(B). This will put B in the IIDF(B).
+    IDFB.insert(&B);
+    IDF[&B].insert(IDFB.begin(), IDFB.end());
+  }
+
+  for (auto I : IDF)
+    for (auto S : I.second)
+      IIDF[S].insert(I.first);
+
+  computePhiInfo();
+
+  NodeAddr<FuncNode*> FA = DFG.getFunc();
+  NodeList Blocks = FA.Addr->members(DFG);
+
+  // Build the phi live-on-entry map.
+  for (NodeAddr<BlockNode*> BA : Blocks) {
+    MachineBasicBlock *MB = BA.Addr->getCode();
+    RefMap &LON = PhiLON[MB];
+    for (auto P : BA.Addr->members_if(DFG.IsCode<NodeAttrs::Phi>, DFG))
+      for (const RefMap::value_type &S : RealUseMap[P.Id])
+        LON[S.first].insert(S.second.begin(), S.second.end());
+  }
+
+  if (Trace) {
+    dbgs() << "Phi live-on-entry map:\n";
+    for (auto &I : PhiLON)
+      dbgs() << "block #" << I.first->getNumber() << " -> "
+             << Print<RefMap>(I.second, DFG) << '\n';
+  }
+
+  // Build the phi live-on-exit map. Each phi node has some set of reached
+  // "real" uses. Propagate this set backwards into the block predecessors
+  // through the reaching defs of the corresponding phi uses.
+  for (NodeAddr<BlockNode*> BA : Blocks) {
+    NodeList Phis = BA.Addr->members_if(DFG.IsCode<NodeAttrs::Phi>, DFG);
+    for (NodeAddr<PhiNode*> PA : Phis) {
+      RefMap &RUs = RealUseMap[PA.Id];
+      if (RUs.empty())
+        continue;
+
+      NodeSet SeenUses;
+      for (auto U : PA.Addr->members_if(DFG.IsRef<NodeAttrs::Use>, DFG)) {
+        if (!SeenUses.insert(U.Id).second)
+          continue;
+        NodeAddr<PhiUseNode*> PUA = U;
+        if (PUA.Addr->getReachingDef() == 0)
+          continue;
+
+        // Each phi has some set (possibly empty) of reached "real" uses,
+        // that is, uses that are part of the compiled program. Such a use
+        // may be located in some farther block, but following a chain of
+        // reaching defs will eventually lead to this phi.
+        // Any chain of reaching defs may fork at a phi node, but there
+        // will be a path upwards that will lead to this phi. Now, this
+        // chain will need to fork at this phi, since some of the reached
+        // uses may have definitions joining in from multiple predecessors.
+        // For each reached "real" use, identify the set of reaching defs
+        // coming from each predecessor P, and add them to PhiLOX[P].
+        //
+        auto PrA = DFG.addr<BlockNode*>(PUA.Addr->getPredecessor());
+        RefMap &LOX = PhiLOX[PrA.Addr->getCode()];
+
+        for (const std::pair<RegisterId,NodeRefSet> &RS : RUs) {
+          // We need to visit each individual use.
+          for (std::pair<NodeId,LaneBitmask> P : RS.second) {
+            // Create a register ref corresponding to the use, and find
+            // all reaching defs starting from the phi use, and treating
+            // all related shadows as a single use cluster.
+            RegisterRef S(RS.first, P.second);
+            NodeList Ds = getAllReachingDefs(S, PUA, true, false, NoRegs);
+            for (NodeAddr<DefNode*> D : Ds)
+              LOX[S.Reg].insert({D.Id, S.Mask});
+          }
+        }
+
+        for (NodeAddr<PhiUseNode*> T : DFG.getRelatedRefs(PA, PUA))
+          SeenUses.insert(T.Id);
+      }  // for U : phi uses
+    }  // for P : Phis
+  }  // for B : Blocks
+
+  if (Trace) {
+    dbgs() << "Phi live-on-exit map:\n";
+    for (auto &I : PhiLOX)
+      dbgs() << "block #" << I.first->getNumber() << " -> "
+             << Print<RefMap>(I.second, DFG) << '\n';
+  }
+
+  RefMap LiveIn;
+  traverse(&MF.front(), LiveIn);
+
+  // Add function live-ins to the live-in set of the function entry block.
+  LiveMap[&MF.front()].insert(DFG.getLiveIns());
+
+  if (Trace) {
+    // Dump the liveness map
+    for (MachineBasicBlock &B : MF) {
+      std::vector<RegisterRef> LV;
+      for (auto I = B.livein_begin(), E = B.livein_end(); I != E; ++I)
+        LV.push_back(RegisterRef(I->PhysReg, I->LaneMask));
+      std::sort(LV.begin(), LV.end());
+      dbgs() << "BB#" << B.getNumber() << "\t rec = {";
+      for (auto I : LV)
+        dbgs() << ' ' << Print<RegisterRef>(I, DFG);
+      dbgs() << " }\n";
+      //dbgs() << "\tcomp = " << Print<RegisterAggr>(LiveMap[&B], DFG) << '\n';
+
+      LV.clear();
+      const RegisterAggr &LG = LiveMap[&B];
+      for (auto I = LG.rr_begin(), E = LG.rr_end(); I != E; ++I)
+        LV.push_back(*I);
+      std::sort(LV.begin(), LV.end());
+      dbgs() << "\tcomp = {";
+      for (auto I : LV)
+        dbgs() << ' ' << Print<RegisterRef>(I, DFG);
+      dbgs() << " }\n";
+
+    }
+  }
+}
+
+
+void Liveness::resetLiveIns() {
+  for (auto &B : DFG.getMF()) {
+    // Remove all live-ins.
+    std::vector<unsigned> T;
+    for (auto I = B.livein_begin(), E = B.livein_end(); I != E; ++I)
+      T.push_back(I->PhysReg);
+    for (auto I : T)
+      B.removeLiveIn(I);
+    // Add the newly computed live-ins.
+    const RegisterAggr &LiveIns = LiveMap[&B];
+    for (auto I = LiveIns.rr_begin(), E = LiveIns.rr_end(); I != E; ++I) {
+      RegisterRef R = *I;
+      B.addLiveIn({MCPhysReg(R.Reg), R.Mask});
+    }
+  }
+}
+
+
+void Liveness::resetKills() {
+  for (auto &B : DFG.getMF())
+    resetKills(&B);
+}
+
+
+void Liveness::resetKills(MachineBasicBlock *B) {
+  auto CopyLiveIns = [this] (MachineBasicBlock *B, BitVector &LV) -> void {
+    for (auto I : B->liveins()) {
+      MCSubRegIndexIterator S(I.PhysReg, &TRI);
+      if (!S.isValid()) {
+        LV.set(I.PhysReg);
+        continue;
+      }
+      do {
+        LaneBitmask M = TRI.getSubRegIndexLaneMask(S.getSubRegIndex());
+        if ((M & I.LaneMask).any())
+          LV.set(S.getSubReg());
+        ++S;
+      } while (S.isValid());
+    }
+  };
+
+  BitVector LiveIn(TRI.getNumRegs()), Live(TRI.getNumRegs());
+  CopyLiveIns(B, LiveIn);
+  for (auto SI : B->successors())
+    CopyLiveIns(SI, Live);
+
+  for (auto I = B->rbegin(), E = B->rend(); I != E; ++I) {
+    MachineInstr *MI = &*I;
+    if (MI->isDebugValue())
+      continue;
+
+    MI->clearKillInfo();
+    for (auto &Op : MI->operands()) {
+      // An implicit def of a super-register may not necessarily start a
+      // live range of it, since an implicit use could be used to keep parts
+      // of it live. Instead of analyzing the implicit operands, ignore
+      // implicit defs.
+      if (!Op.isReg() || !Op.isDef() || Op.isImplicit())
+        continue;
+      unsigned R = Op.getReg();
+      if (!TargetRegisterInfo::isPhysicalRegister(R))
+        continue;
+      for (MCSubRegIterator SR(R, &TRI, true); SR.isValid(); ++SR)
+        Live.reset(*SR);
+    }
+    for (auto &Op : MI->operands()) {
+      if (!Op.isReg() || !Op.isUse() || Op.isUndef())
+        continue;
+      unsigned R = Op.getReg();
+      if (!TargetRegisterInfo::isPhysicalRegister(R))
+        continue;
+      bool IsLive = false;
+      for (MCRegAliasIterator AR(R, &TRI, true); AR.isValid(); ++AR) {
+        if (!Live[*AR])
+          continue;
+        IsLive = true;
+        break;
+      }
+      if (!IsLive)
+        Op.setIsKill(true);
+      for (MCSubRegIterator SR(R, &TRI, true); SR.isValid(); ++SR)
+        Live.set(*SR);
+    }
+  }
+}
+
+
+// Helper function to obtain the basic block containing the reaching def
+// of the given use.
+MachineBasicBlock *Liveness::getBlockWithRef(NodeId RN) const {
+  auto F = NBMap.find(RN);
+  if (F != NBMap.end())
+    return F->second;
+  llvm_unreachable("Node id not in map");
+}
+
+
+void Liveness::traverse(MachineBasicBlock *B, RefMap &LiveIn) {
+  // The LiveIn map, for each (physical) register, contains the set of live
+  // reaching defs of that register that are live on entry to the associated
+  // block.
+
+  // The summary of the traversal algorithm:
+  //
+  // R is live-in in B, if there exists a U(R), such that rdef(R) dom B
+  // and (U \in IDF(B) or B dom U).
+  //
+  // for (C : children) {
+  //   LU = {}
+  //   traverse(C, LU)
+  //   LiveUses += LU
+  // }
+  //
+  // LiveUses -= Defs(B);
+  // LiveUses += UpwardExposedUses(B);
+  // for (C : IIDF[B])
+  //   for (U : LiveUses)
+  //     if (Rdef(U) dom C)
+  //       C.addLiveIn(U)
+  //
+
+  // Go up the dominator tree (depth-first).
+  MachineDomTreeNode *N = MDT.getNode(B);
+  for (auto I : *N) {
+    RefMap L;
+    MachineBasicBlock *SB = I->getBlock();
+    traverse(SB, L);
+
+    for (auto S : L)
+      LiveIn[S.first].insert(S.second.begin(), S.second.end());
+  }
+
+  if (Trace) {
+    dbgs() << "\n-- BB#" << B->getNumber() << ": " << __func__
+           << " after recursion into: {";
+    for (auto I : *N)
+      dbgs() << ' ' << I->getBlock()->getNumber();
+    dbgs() << " }\n";
+    dbgs() << "  LiveIn: " << Print<RefMap>(LiveIn, DFG) << '\n';
+    dbgs() << "  Local:  " << Print<RegisterAggr>(LiveMap[B], DFG) << '\n';
+  }
+
+  // Add reaching defs of phi uses that are live on exit from this block.
+  RefMap &PUs = PhiLOX[B];
+  for (auto &S : PUs)
+    LiveIn[S.first].insert(S.second.begin(), S.second.end());
+
+  if (Trace) {
+    dbgs() << "after LOX\n";
+    dbgs() << "  LiveIn: " << Print<RefMap>(LiveIn, DFG) << '\n';
+    dbgs() << "  Local:  " << Print<RegisterAggr>(LiveMap[B], DFG) << '\n';
+  }
+
+  // The LiveIn map at this point has all defs that are live-on-exit from B,
+  // as if they were live-on-entry to B. First, we need to filter out all
+  // defs that are present in this block. Then we will add reaching defs of
+  // all upward-exposed uses.
+
+  // To filter out the defs, first make a copy of LiveIn, and then re-populate
+  // LiveIn with the defs that should remain.
+  RefMap LiveInCopy = LiveIn;
+  LiveIn.clear();
+
+  for (const std::pair<RegisterId,NodeRefSet> &LE : LiveInCopy) {
+    RegisterRef LRef(LE.first);
+    NodeRefSet &NewDefs = LiveIn[LRef.Reg]; // To be filled.
+    const NodeRefSet &OldDefs = LE.second;
+    for (NodeRef OR : OldDefs) {
+      // R is a def node that was live-on-exit
+      auto DA = DFG.addr<DefNode*>(OR.first);
+      NodeAddr<InstrNode*> IA = DA.Addr->getOwner(DFG);
+      NodeAddr<BlockNode*> BA = IA.Addr->getOwner(DFG);
+      if (B != BA.Addr->getCode()) {
+        // Defs from a different block need to be preserved. Defs from this
+        // block will need to be processed further, except for phi defs, the
+        // liveness of which is handled through the PhiLON/PhiLOX maps.
+        NewDefs.insert(OR);
+        continue;
+      }
+
+      // Defs from this block need to stop the liveness from being
+      // propagated upwards. This only applies to non-preserving defs,
+      // and to the parts of the register actually covered by those defs.
+      // (Note that phi defs should always be preserving.)
+      RegisterAggr RRs(PRI);
+      LRef.Mask = OR.second;
+
+      if (!DFG.IsPreservingDef(DA)) {
+        assert(!(IA.Addr->getFlags() & NodeAttrs::Phi));
+        // DA is a non-phi def that is live-on-exit from this block, and
+        // that is also located in this block. LRef is a register ref
+        // whose use this def reaches. If DA covers LRef, then no part
+        // of LRef is exposed upwards.A
+        if (RRs.insert(DA.Addr->getRegRef(DFG)).hasCoverOf(LRef))
+          continue;
+      }
+
+      // DA itself was not sufficient to cover LRef. In general, it is
+      // the last in a chain of aliased defs before the exit from this block.
+      // There could be other defs in this block that are a part of that
+      // chain. Check that now: accumulate the registers from these defs,
+      // and if they all together cover LRef, it is not live-on-entry.
+      for (NodeAddr<DefNode*> TA : getAllReachingDefs(DA)) {
+        // DefNode -> InstrNode -> BlockNode.
+        NodeAddr<InstrNode*> ITA = TA.Addr->getOwner(DFG);
+        NodeAddr<BlockNode*> BTA = ITA.Addr->getOwner(DFG);
+        // Reaching defs are ordered in the upward direction.
+        if (BTA.Addr->getCode() != B) {
+          // We have reached past the beginning of B, and the accumulated
+          // registers are not covering LRef. The first def from the
+          // upward chain will be live.
+          // Subtract all accumulated defs (RRs) from LRef.
+          RegisterRef T = RRs.clearIn(LRef);
+          assert(T);
+          NewDefs.insert({TA.Id,T.Mask});
+          break;
+        }
+
+        // TA is in B. Only add this def to the accumulated cover if it is
+        // not preserving.
+        if (!(TA.Addr->getFlags() & NodeAttrs::Preserving))
+          RRs.insert(TA.Addr->getRegRef(DFG));
+        // If this is enough to cover LRef, then stop.
+        if (RRs.hasCoverOf(LRef))
+          break;
+      }
+    }
+  }
+
+  emptify(LiveIn);
+
+  if (Trace) {
+    dbgs() << "after defs in block\n";
+    dbgs() << "  LiveIn: " << Print<RefMap>(LiveIn, DFG) << '\n';
+    dbgs() << "  Local:  " << Print<RegisterAggr>(LiveMap[B], DFG) << '\n';
+  }
+
+  // Scan the block for upward-exposed uses and add them to the tracking set.
+  for (auto I : DFG.getFunc().Addr->findBlock(B, DFG).Addr->members(DFG)) {
+    NodeAddr<InstrNode*> IA = I;
+    if (IA.Addr->getKind() != NodeAttrs::Stmt)
+      continue;
+    for (NodeAddr<UseNode*> UA : IA.Addr->members_if(DFG.IsUse, DFG)) {
+      if (UA.Addr->getFlags() & NodeAttrs::Undef)
+        continue;
+      RegisterRef RR = PRI.normalize(UA.Addr->getRegRef(DFG));
+      for (NodeAddr<DefNode*> D : getAllReachingDefs(UA))
+        if (getBlockWithRef(D.Id) != B)
+          LiveIn[RR.Reg].insert({D.Id,RR.Mask});
+    }
+  }
+
+  if (Trace) {
+    dbgs() << "after uses in block\n";
+    dbgs() << "  LiveIn: " << Print<RefMap>(LiveIn, DFG) << '\n';
+    dbgs() << "  Local:  " << Print<RegisterAggr>(LiveMap[B], DFG) << '\n';
+  }
+
+  // Phi uses should not be propagated up the dominator tree, since they
+  // are not dominated by their corresponding reaching defs.
+  RegisterAggr &Local = LiveMap[B];
+  RefMap &LON = PhiLON[B];
+  for (auto &R : LON) {
+    LaneBitmask M;
+    for (auto P : R.second)
+      M |= P.second;
+    Local.insert(RegisterRef(R.first,M));
+  }
+
+  if (Trace) {
+    dbgs() << "after phi uses in block\n";
+    dbgs() << "  LiveIn: " << Print<RefMap>(LiveIn, DFG) << '\n';
+    dbgs() << "  Local:  " << Print<RegisterAggr>(Local, DFG) << '\n';
+  }
+
+  for (auto C : IIDF[B]) {
+    RegisterAggr &LiveC = LiveMap[C];
+    for (const std::pair<RegisterId,NodeRefSet> &S : LiveIn)
+      for (auto R : S.second)
+        if (MDT.properlyDominates(getBlockWithRef(R.first), C))
+          LiveC.insert(RegisterRef(S.first, R.second));
+  }
+}
+
+
+void Liveness::emptify(RefMap &M) {
+  for (auto I = M.begin(), E = M.end(); I != E; )
+    I = I->second.empty() ? M.erase(I) : std::next(I);
+}
+

lib/CodeGen/RDFRegisters.cpp

+//===--- RDFRegisters.cpp ---------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/BitVector.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/RDFRegisters.h"
+
+using namespace llvm;
+using namespace rdf;
+
+PhysicalRegisterInfo::PhysicalRegisterInfo(const TargetRegisterInfo &tri,
+      const MachineFunction &mf)
+    : TRI(tri) {
+  RegInfos.resize(TRI.getNumRegs());
+
+  BitVector BadRC(TRI.getNumRegs());
+  for (const TargetRegisterClass *RC : TRI.regclasses()) {
+    for (MCPhysReg R : *RC) {
+      RegInfo &RI = RegInfos[R];
+      if (RI.RegClass != nullptr && !BadRC[R]) {
+        if (RC->LaneMask != RI.RegClass->LaneMask) {
+          BadRC.set(R);
+          RI.RegClass = nullptr;
+        }
+      } else
+        RI.RegClass = RC;
+    }
+  }
+
+  UnitInfos.resize(TRI.getNumRegUnits());
+
+  for (uint32_t U = 0, NU = TRI.getNumRegUnits(); U != NU; ++U) {
+    if (UnitInfos[U].Reg != 0)
+      continue;
+    MCRegUnitRootIterator R(U, &TRI);
+    assert(R.isValid());
+    RegisterId F = *R;
+    ++R;
+    if (R.isValid()) {
+      UnitInfos[U].Mask = LaneBitmask::getAll();
+      UnitInfos[U].Reg = F;
+    } else {
+      for (MCRegUnitMaskIterator I(F, &TRI); I.isValid(); ++I) {
+        std::pair<uint32_t,LaneBitmask> P = *I;
+        UnitInfo &UI = UnitInfos[P.first];
+        UI.Reg = F;
+        if (P.second.any()) {
+          UI.Mask = P.second;
+        } else {
+          if (const TargetRegisterClass *RC = RegInfos[F].RegClass)
+            UI.Mask = RC->LaneMask;
+          else
+            UI.Mask = LaneBitmask::getAll();
+        }
+      }
+    }
+  }
+
+  for (const uint32_t *RM : TRI.getRegMasks())
+    RegMasks.insert(RM);
+  for (const MachineBasicBlock &B : mf)
+    for (const MachineInstr &In : B)
+      for (const MachineOperand &Op : In.operands())
+        if (Op.isRegMask())
+          RegMasks.insert(Op.getRegMask());
+}
+
+RegisterRef PhysicalRegisterInfo::normalize(RegisterRef RR) const {
+  return RR;
+}
+
+std::set<RegisterId> PhysicalRegisterInfo::getAliasSet(RegisterId Reg) const {
+  // Do not include RR in the alias set.
+  std::set<RegisterId> AS;
+  assert(isRegMaskId(Reg) || TargetRegisterInfo::isPhysicalRegister(Reg));
+  if (isRegMaskId(Reg)) {
+    // XXX SLOW
+    const uint32_t *MB = getRegMaskBits(Reg);
+    for (unsigned i = 1, e = TRI.getNumRegs(); i != e; ++i) {
+      if (MB[i/32] & (1u << (i%32)))
+        continue;
+      AS.insert(i);
+    }
+    for (const uint32_t *RM : RegMasks) {
+      RegisterId MI = getRegMaskId(RM);
+      if (MI != Reg && aliasMM(RegisterRef(Reg), RegisterRef(MI)))
+        AS.insert(MI);
+    }
+    return AS;
+  }
+
+  for (MCRegAliasIterator AI(Reg, &TRI, false); AI.isValid(); ++AI)
+    AS.insert(*AI);
+  for (const uint32_t *RM : RegMasks) {
+    RegisterId MI = getRegMaskId(RM);
+    if (aliasRM(RegisterRef(Reg), RegisterRef(MI)))
+      AS.insert(MI);
+  }
+  return AS;
+}
+
+bool PhysicalRegisterInfo::aliasRR(RegisterRef RA, RegisterRef RB) const {
+  assert(TargetRegisterInfo::isPhysicalRegister(RA.Reg));
+  assert(TargetRegisterInfo::isPhysicalRegister(RB.Reg));
+
+  MCRegUnitMaskIterator UMA(RA.Reg, &TRI);
+  MCRegUnitMaskIterator UMB(RB.Reg, &TRI);
+  // Reg units are returned in the numerical order.
+  while (UMA.isValid() && UMB.isValid()) {
+    // Skip units that are masked off in RA.
+    std::pair<RegisterId,LaneBitmask> PA = *UMA;
+    if (PA.second.any() && (PA.second & RA.Mask).none()) {
+      ++UMA;
+      continue;
+    }
+    // Skip units that are masked off in RB.
+    std::pair<RegisterId,LaneBitmask> PB = *UMB;
+    if (PB.second.any() && (PB.second & RB.Mask).none()) {
+      ++UMB;
+      continue;
+    }
+
+    if (PA.first == PB.first)
+      return true;
+    if (PA.first < PB.first)
+      ++UMA;
+    else if (PB.first < PA.first)
+      ++UMB;
+  }
+  return false;
+}
+
+bool PhysicalRegisterInfo::aliasRM(RegisterRef RR, RegisterRef RM) const {
+  assert(TargetRegisterInfo::isPhysicalRegister(RR.Reg) && isRegMaskId(RM.Reg));
+  const uint32_t *MB = getRegMaskBits(RM.Reg);
+  bool Preserved = MB[RR.Reg/32] & (1u << (RR.Reg%32));
+  // If the lane mask information is "full", e.g. when the given lane mask
+  // is a superset of the lane mask from the register class, check the regmask
+  // bit directly.
+  if (RR.Mask == LaneBitmask::getAll())
+    return !Preserved;
+  const TargetRegisterClass *RC = RegInfos[RR.Reg].RegClass;
+  if (RC != nullptr && (RR.Mask & RC->LaneMask) == RC->LaneMask)
+    return !Preserved;
+
+  // Otherwise, check all subregisters whose lane mask overlaps the given
+  // mask. For each such register, if it is preserved by the regmask, then
+  // clear the corresponding bits in the given mask. If at the end, all
+  // bits have been cleared, the register does not alias the regmask (i.e.
+  // is it preserved by it).
+  LaneBitmask M = RR.Mask;
+  for (MCSubRegIndexIterator SI(RR.Reg, &TRI); SI.isValid(); ++SI) {
+    LaneBitmask SM = TRI.getSubRegIndexLaneMask(SI.getSubRegIndex());
+    if ((SM & RR.Mask).none())
+      continue;
+    unsigned SR = SI.getSubReg();
+    if (!(MB[SR/32] & (1u << (SR%32))))
+      continue;
+    // The subregister SR is preserved.
+    M &= ~SM;
+    if (M.none())
+      return false;
+  }
+
+  return true;
+}
+
+bool PhysicalRegisterInfo::aliasMM(RegisterRef RM, RegisterRef RN) const {
+  assert(isRegMaskId(RM.Reg) && isRegMaskId(RN.Reg));
+  unsigned NumRegs = TRI.getNumRegs();
+  const uint32_t *BM = getRegMaskBits(RM.Reg);
+  const uint32_t *BN = getRegMaskBits(RN.Reg);
+
+  for (unsigned w = 0, nw = NumRegs/32; w != nw; ++w) {
+    // Intersect the negations of both words. Disregard reg=0,
+    // i.e. 0th bit in the 0th word.
+    uint32_t C = ~BM[w] & ~BN[w];
+    if (w == 0)
+      C &= ~1;
+    if (C)
+      return true;
+  }
+
+  // Check the remaining registers in the last word.
+  unsigned TailRegs = NumRegs % 32;
+  if (TailRegs == 0)
+    return false;
+  unsigned TW = NumRegs / 32;
+  uint32_t TailMask = (1u << TailRegs) - 1;
+  if (~BM[TW] & ~BN[TW] & TailMask)
+    return true;
+
+  return false;
+}
+
+
+bool RegisterAggr::hasAliasOf(RegisterRef RR) const {
+  if (PhysicalRegisterInfo::isRegMaskId(RR.Reg)) {
+    // XXX SLOW
+    const uint32_t *MB = PRI.getRegMaskBits(RR.Reg);
+    for (unsigned i = 1, e = PRI.getTRI().getNumRegs(); i != e; ++i) {
+      if (MB[i/32] & (1u << (i%32)))
+        continue;
+      if (hasAliasOf(RegisterRef(i, LaneBitmask::getAll())))
+        return true;
+    }
+    return false;
+  }
+
+  for (MCRegUnitMaskIterator U(RR.Reg, &PRI.getTRI()); U.isValid(); ++U) {
+    std::pair<uint32_t,LaneBitmask> P = *U;
+    if (P.second.none() || (P.second & RR.Mask).any())
+      if (Units.test(P.first))
+        return true;
+  }
+  return false;
+}
+
+bool RegisterAggr::hasCoverOf(RegisterRef RR) const {
+  if (PhysicalRegisterInfo::isRegMaskId(RR.Reg)) {
+    // XXX SLOW
+    const uint32_t *MB = PRI.getRegMaskBits(RR.Reg);
+    for (unsigned i = 1, e = PRI.getTRI().getNumRegs(); i != e; ++i) {
+      if (MB[i/32] & (1u << (i%32)))
+        continue;
+      if (!hasCoverOf(RegisterRef(i, LaneBitmask::getAll())))
+        return false;
+    }
+    return true;
+  }
+
+  for (MCRegUnitMaskIterator U(RR.Reg, &PRI.getTRI()); U.isValid(); ++U) {
+    std::pair<uint32_t,LaneBitmask> P = *U;
+    if (P.second.none() || (P.second & RR.Mask).any())
+      if (!Units.test(P.first))
+        return false;
+  }
+  return true;
+}
+
+RegisterAggr &RegisterAggr::insert(RegisterRef RR) {
+  if (PhysicalRegisterInfo::isRegMaskId(RR.Reg)) {
+    BitVector PU(PRI.getTRI().getNumRegUnits()); // Preserved units.
+    const uint32_t *MB = PRI.getRegMaskBits(RR.Reg);
+    for (unsigned i = 1, e = PRI.getTRI().getNumRegs(); i != e; ++i) {
+      if (!(MB[i/32] & (1u << (i%32))))
+        continue;
+      for (MCRegUnitIterator U(i, &PRI.getTRI()); U.isValid(); ++U)
+        PU.set(*U);
+    }
+    Units |= PU.flip();
+    return *this;
+  }
+
+  for (MCRegUnitMaskIterator U(RR.Reg, &PRI.getTRI()); U.isValid(); ++U) {
+    std::pair<uint32_t,LaneBitmask> P = *U;
+    if (P.second.none() || (P.second & RR.Mask).any())
+      Units.set(P.first);
+  }
+  return *this;
+}
+
+RegisterAggr &RegisterAggr::insert(const RegisterAggr &RG) {
+  Units |= RG.Units;
+  return *this;
+}
+
+RegisterAggr &RegisterAggr::intersect(RegisterRef RR) {
+  return intersect(RegisterAggr(PRI).insert(RR));
+}
+
+RegisterAggr &RegisterAggr::intersect(const RegisterAggr &RG) {
+  Units &= RG.Units;
+  return *this;
+}
+
+RegisterAggr &RegisterAggr::clear(RegisterRef RR) {
+  return clear(RegisterAggr(PRI).insert(RR));
+}
+
+RegisterAggr &RegisterAggr::clear(const RegisterAggr &RG) {
+  Units.reset(RG.Units);
+  return *this;
+}
+
+RegisterRef RegisterAggr::intersectWith(RegisterRef RR) const {
+  RegisterAggr T(PRI);
+  T.insert(RR).intersect(*this);
+  if (T.empty())
+    return RegisterRef();
+  RegisterRef NR = T.makeRegRef();
+  assert(NR);
+  return NR;
+}
+
+RegisterRef RegisterAggr::clearIn(RegisterRef RR) const {
+  return RegisterAggr(PRI).insert(RR).clear(*this).makeRegRef();
+}
+
+RegisterRef RegisterAggr::makeRegRef() const {
+  int U = Units.find_first();
+  if (U < 0)
+    return RegisterRef();
+
+  auto AliasedRegs = [this] (uint32_t Unit, BitVector &Regs) {
+    for (MCRegUnitRootIterator R(Unit, &PRI.getTRI()); R.isValid(); ++R)
+      for (MCSuperRegIterator S(*R, &PRI.getTRI(), true); S.isValid(); ++S)
+        Regs.set(*S);
+  };
+
+  // Find the set of all registers that are aliased to all the units
+  // in this aggregate.
+
+  // Get all the registers aliased to the first unit in the bit vector.
+  BitVector Regs(PRI.getTRI().getNumRegs());
+  AliasedRegs(U, Regs);
+  U = Units.find_next(U);
+
+  // For each other unit, intersect it with the set of all registers
+  // aliased that unit.
+  while (U >= 0) {
+    BitVector AR(PRI.getTRI().getNumRegs());
+    AliasedRegs(U, AR);
+    Regs &= AR;
+    U = Units.find_next(U);
+  }
+
+  // If there is at least one register remaining, pick the first one,
+  // and consolidate the masks of all of its units contained in this
+  // aggregate.
+
+  int F = Regs.find_first();
+  if (F <= 0)
+    return RegisterRef();
+
+  LaneBitmask M;
+  for (MCRegUnitMaskIterator I(F, &PRI.getTRI()); I.isValid(); ++I) {
+    std::pair<uint32_t,LaneBitmask> P = *I;
+    if (Units.test(P.first))
+      M |= P.second.none() ? LaneBitmask::getAll() : P.second;
+  }
+  return RegisterRef(F, M);
+}
+
+void RegisterAggr::print(raw_ostream &OS) const {
+  OS << '{';
+  for (int U = Units.find_first(); U >= 0; U = Units.find_next(U))
+    OS << ' ' << PrintRegUnit(U, &PRI.getTRI());
+  OS << " }";
+}
+
+RegisterAggr::rr_iterator::rr_iterator(const RegisterAggr &RG,
+      bool End)
+    : Owner(&RG) {
+  for (int U = RG.Units.find_first(); U >= 0; U = RG.Units.find_next(U)) {
+    RegisterRef R = RG.PRI.getRefForUnit(U);
+    Masks[R.Reg] |= R.Mask;
+  }
+  Pos = End ? Masks.end() : Masks.begin();
+  Index = End ? Masks.size() : 0;
+}
+

lib/Target/Hexagon/CMakeLists.txt

add_llvm_target(HexagonCodeGen
   HexagonSubtarget.cpp
   HexagonTargetMachine.cpp
   HexagonTargetObjectFile.cpp
   HexagonTargetTransformInfo.cpp
   HexagonVectorPrint.cpp
   HexagonVLIWPacketizer.cpp
   RDFCopy.cpp
   RDFDeadCode.cpp
-  RDFGraph.cpp
-  RDFLiveness.cpp
-  RDFRegisters.cpp
 )
 
 add_subdirectory(AsmParser)
 add_subdirectory(TargetInfo)
 add_subdirectory(MCTargetDesc)
 add_subdirectory(Disassembler)

lib/Target/Hexagon/HexagonOptAddrMode.cpp

 // load/store instructions.
 //===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "opt-addr-mode"
 
 #include "HexagonInstrInfo.h"
 #include "HexagonSubtarget.h"
 #include "MCTargetDesc/HexagonBaseInfo.h"
-#include "RDFGraph.h"
-#include "RDFLiveness.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
 #include "llvm/CodeGen/MachineDominanceFrontier.h"
 #include "llvm/CodeGen/MachineDominators.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineInstr.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineOperand.h"
+#include "llvm/CodeGen/RDFGraph.h"
+#include "llvm/CodeGen/RDFLiveness.h"
 #include "llvm/MC/MCInstrDesc.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cassert>
 #include <cstdint>

lib/Target/Hexagon/HexagonRDFOpt.cpp

 //===--- HexagonRDFOpt.cpp ------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #include "HexagonInstrInfo.h"
 #include "HexagonSubtarget.h"
 #include "RDFCopy.h"
 #include "RDFDeadCode.h"
-#include "RDFGraph.h"
-#include "RDFLiveness.h"
 #include "llvm/ADT/SetVector.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
 #include "llvm/CodeGen/MachineDominanceFrontier.h"
 #include "llvm/CodeGen/MachineDominators.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/RDFGraph.h"
+#include "llvm/CodeGen/RDFLiveness.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetRegisterInfo.h"
 
 using namespace llvm;
 using namespace rdf;
 

lib/Target/Hexagon/RDFCopy.h

 //===--- RDFCopy.h ----------------------------------------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_LIB_TARGET_HEXAGON_RDFCOPY_H
 #define LLVM_LIB_TARGET_HEXAGON_RDFCOPY_H
 
-#include "RDFGraph.h"
-#include "RDFLiveness.h"
 #include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/RDFGraph.h"
+#include "llvm/CodeGen/RDFLiveness.h"
 
 #include <map>
 #include <vector>
 
 namespace llvm {
 
   class MachineBasicBlock;
   class MachineDominatorTree;

lib/Target/Hexagon/RDFCopy.cpp

 //===--- RDFCopy.cpp ------------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // RDF-based copy propagation.
 
 #include "RDFCopy.h"
-#include "RDFGraph.h"
-#include "RDFLiveness.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
 #include "llvm/CodeGen/MachineDominators.h"
 #include "llvm/CodeGen/MachineInstr.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/RDFGraph.h"
+#include "llvm/CodeGen/RDFLiveness.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetRegisterInfo.h"
 using namespace llvm;
 using namespace rdf;
 
 #ifndef NDEBUG
 static cl::opt<unsigned> CpLimit("rdf-cp-limit", cl::init(0), cl::Hidden);

lib/Target/Hexagon/RDFDeadCode.h

 // or not, and if it is, convert the instruction to a non-updating form.
 // After that "erase" can be called with the set of nodes including both,
 // dead defs from the updating instructions and the nodes corresponding
 // to the dead instructions.
 
 #ifndef RDF_DEADCODE_H
 #define RDF_DEADCODE_H
 
-#include "RDFGraph.h"
-#include "RDFLiveness.h"
 #include "llvm/ADT/SetVector.h"
+#include "llvm/CodeGen/RDFGraph.h"
+#include "llvm/CodeGen/RDFLiveness.h"
 
 namespace llvm {
   class MachineRegisterInfo;
 
 namespace rdf {
   struct DeadCodeElimination {
     DeadCodeElimination(DataFlowGraph &dfg, MachineRegisterInfo &mri)
       : Trace(false), DFG(dfg), MRI(mri), LV(mri, dfg) {}

lib/Target/Hexagon/RDFDeadCode.cpp

 //===--- RDFDeadCode.cpp --------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // RDF-based generic dead code elimination.
 
-#include "RDFGraph.h"
-#include "RDFLiveness.h"
 #include "RDFDeadCode.h"
 
 #include "llvm/ADT/SetVector.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/RDFGraph.h"
+#include "llvm/CodeGen/RDFLiveness.h"
 
 #include <queue>
 
 using namespace llvm;
 using namespace rdf;
 
 // This drastically improves execution time in "collect" over using
 // SetVector as a work queue, and popping the first element from it.

lib/Target/Hexagon/RDFGraph.h

-//===--- RDFGraph.h ---------------------------------------------*- C++ -*-===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// Target-independent, SSA-based data flow graph for register data flow (RDF)
-// for a non-SSA program representation (e.g. post-RA machine code).
-//
-//
-// *** Introduction
-//
-// The RDF graph is a collection of nodes, each of which denotes some element
-// of the program. There are two main types of such elements: code and refe-
-// rences. Conceptually, "code" is something that represents the structure
-// of the program, e.g. basic block or a statement, while "reference" is an
-// instance of accessing a register, e.g. a definition or a use. Nodes are
-// connected with each other based on the structure of the program (such as
-// blocks, instructions, etc.), and based on the data flow (e.g. reaching
-// definitions, reached uses, etc.). The single-reaching-definition principle
-// of SSA is generally observed, although, due to the non-SSA representation
-// of the program, there are some differences between the graph and a "pure"
-// SSA representation.
-//
-//
-// *** Implementation remarks
-//
-// Since the graph can contain a large number of nodes, memory consumption
-// was one of the major design considerations. As a result, there is a single
-// base class NodeBase which defines all members used by all possible derived
-// classes. The members are arranged in a union, and a derived class cannot
-// add any data members of its own. Each derived class only defines the
-// functional interface, i.e. member functions. NodeBase must be a POD,
-// which implies that all of its members must also be PODs.
-// Since nodes need to be connected with other nodes, pointers have been
-// replaced with 32-bit identifiers: each node has an id of type NodeId.
-// There are mapping functions in the graph that translate between actual
-// memory addresses and the corresponding identifiers.
-// A node id of 0 is equivalent to nullptr.
-//
-//
-// *** Structure of the graph
-//
-// A code node is always a collection of other nodes. For example, a code
-// node corresponding to a basic block will contain code nodes corresponding
-// to instructions. In turn, a code node corresponding to an instruction will
-// contain a list of reference nodes that correspond to the definitions and
-// uses of registers in that instruction. The members are arranged into a
-// circular list, which is yet another consequence of the effort to save
-// memory: for each member node it should be possible to obtain its owner,
-// and it should be possible to access all other members. There are other
-// ways to accomplish that, but the circular list seemed the most natural.
-//
-// +- CodeNode -+
-// |            | <---------------------------------------------------+
-// +-+--------+-+                                                     |
-//   |FirstM  |LastM                                                  |
-//   |        +-------------------------------------+                 |
-//   |                                              |                 |
-//   V                                              V                 |
-//  +----------+ Next +----------+ Next       Next +----------+ Next  |
-//  |          |----->|          |-----> ... ----->|          |----->-+
-//  +- Member -+      +- Member -+                 +- Member -+
-//
-// The order of members is such that related reference nodes (see below)
-// should be contiguous on the member list.
-//
-// A reference node is a node that encapsulates an access to a register,
-// in other words, data flowing into or out of a register. There are two
-// major kinds of reference nodes: defs and uses. A def node will contain
-// the id of the first reached use, and the id of the first reached def.
-// Each def and use will contain the id of the reaching def, and also the
-// id of the next reached def (for def nodes) or use (for use nodes).
-// The "next node sharing the same reaching def" is denoted as "sibling".
-// In summary:
-// - Def node contains: reaching def, sibling, first reached def, and first
-// reached use.
-// - Use node contains: reaching def and sibling.
-//
-// +-- DefNode --+
-// | R2 = ...    | <---+--------------------+
-// ++---------+--+     |                    |
-//  |Reached  |Reached |                    |
-//  |Def      |Use     |                    |
-//  |         |        |Reaching            |Reaching
-//  |         V        |Def                 |Def
-//  |      +-- UseNode --+ Sib  +-- UseNode --+ Sib       Sib
-//  |      | ... = R2    |----->| ... = R2    |----> ... ----> 0
-//  |      +-------------+      +-------------+
-//  V
-// +-- DefNode --+ Sib
-// | R2 = ...    |----> ...
-// ++---------+--+
-//  |         |
-//  |         |
-// ...       ...
-//
-// To get a full picture, the circular lists connecting blocks within a
-// function, instructions within a block, etc. should be superimposed with
-// the def-def, def-use links shown above.
-// To illustrate this, consider a small example in a pseudo-assembly:
-// foo:
-//   add r2, r0, r1   ; r2 = r0+r1
-//   addi r0, r2, 1   ; r0 = r2+1
-//   ret r0           ; return value in r0
-//
-// The graph (in a format used by the debugging functions) would look like:
-//
-//   DFG dump:[
-//   f1: Function foo
-//   b2: === BB#0 === preds(0), succs(0):
-//   p3: phi [d4<r0>(,d12,u9):]
-//   p5: phi [d6<r1>(,,u10):]
-//   s7: add [d8<r2>(,,u13):, u9<r0>(d4):, u10<r1>(d6):]
-//   s11: addi [d12<r0>(d4,,u15):, u13<r2>(d8):]
-//   s14: ret [u15<r0>(d12):]
-//   ]
-//
-// The f1, b2, p3, etc. are node ids. The letter is prepended to indicate the
-// kind of the node (i.e. f - function, b - basic block, p - phi, s - state-
-// ment, d - def, u - use).
-// The format of a def node is:
-//   dN<R>(rd,d,u):sib,
-// where
-//   N   - numeric node id,
-//   R   - register being defined
-//   rd  - reaching def,
-//   d   - reached def,
-//   u   - reached use,
-//   sib - sibling.
-// The format of a use node is:
-//   uN<R>[!](rd):sib,
-// where
-//   N   - numeric node id,
-//   R   - register being used,
-//   rd  - reaching def,
-//   sib - sibling.
-// Possible annotations (usually preceding the node id):
-//   +   - preserving def,
-//   ~   - clobbering def,
-//   "   - shadow ref (follows the node id),
-//   !   - fixed register (appears after register name).
-//
-// The circular lists are not explicit in the dump.
-//
-//
-// *** Node attributes
-//
-// NodeBase has a member "Attrs", which is the primary way of determining
-// the node's characteristics. The fields in this member decide whether
-// the node is a code node or a reference node (i.e. node's "type"), then
-// within each type, the "kind" determines what specifically this node
-// represents. The remaining bits, "flags", contain additional information
-// that is even more detailed than the "kind".
-// CodeNode's kinds are:
-// - Phi:   Phi node, members are reference nodes.
-// - Stmt:  Statement, members are reference nodes.
-// - Block: Basic block, members are instruction nodes (i.e. Phi or Stmt).
-// - Func:  The whole function. The members are basic block nodes.
-// RefNode's kinds are:
-// - Use.
-// - Def.
-//
-// Meaning of flags:
-// - Preserving: applies only to defs. A preserving def is one that can
-//   preserve some of the original bits among those that are included in
-//   the register associated with that def. For example, if R0 is a 32-bit
-//   register, but a def can only change the lower 16 bits, then it will
-//   be marked as preserving.
-// - Shadow: a reference that has duplicates holding additional reaching
-//   defs (see more below).
-// - Clobbering: applied only to defs, indicates that the value generated
-//   by this def is unspecified. A typical example would be volatile registers
-//   after function calls.
-// - Fixed: the register in this def/use cannot be replaced with any other
-//   register. A typical case would be a parameter register to a call, or
-//   the register with the return value from a function.
-// - Undef: the register in this reference the register is assumed to have
-//   no pre-existing value, even if it appears to be reached by some def.
-//   This is typically used to prevent keeping registers artificially live
-//   in cases when they are defined via predicated instructions. For example:
-//     r0 = add-if-true cond, r10, r11                (1)
-//     r0 = add-if-false cond, r12, r13, r0<imp-use>  (2)
-//     ... = r0                                       (3)
-//   Before (1), r0 is not intended to be live, and the use of r0 in (3) is
-//   not meant to be reached by any def preceding (1). However, since the
-//   defs in (1) and (2) are both preserving, these properties alone would
-//   imply that the use in (3) may indeed be reached by some prior def.
-//   Adding Undef flag to the def in (1) prevents that. The Undef flag
-//   may be applied to both defs and uses.
-// - Dead: applies only to defs. The value coming out of a "dead" def is
-//   assumed to be unused, even if the def appears to be reaching other defs
-//   or uses. The motivation for this flag comes from dead defs on function
-//   calls: there is no way to determine if such a def is dead without
-//   analyzing the target's ABI. Hence the graph should contain this info,
-//   as it is unavailable otherwise. On the other hand, a def without any
-//   uses on a typical instruction is not the intended target for this flag.
-//
-// *** Shadow references
-//
-// It may happen that a super-register can have two (or more) non-overlapping
-// sub-registers. When both of these sub-registers are defined and followed
-// by a use of the super-register, the use of the super-register will not
-// have a unique reaching def: both defs of the sub-registers need to be
-// accounted for. In such cases, a duplicate use of the super-register is
-// added and it points to the extra reaching def. Both uses are marked with
-// a flag "shadow". Example:
-// Assume t0 is a super-register of r0 and r1, r0 and r1 do not overlap:
-//   set r0, 1        ; r0 = 1
-//   set r1, 1        ; r1 = 1
-//   addi t1, t0, 1   ; t1 = t0+1
-//
-// The DFG:
-//   s1: set [d2<r0>(,,u9):]
-//   s3: set [d4<r1>(,,u10):]
-//   s5: addi [d6<t1>(,,):, u7"<t0>(d2):, u8"<t0>(d4):]
-//
-// The statement s5 has two use nodes for t0: u7" and u9". The quotation
-// mark " indicates that the node is a shadow.
-//
-
-#ifndef LLVM_LIB_TARGET_HEXAGON_RDFGRAPH_H
-#define LLVM_LIB_TARGET_HEXAGON_RDFGRAPH_H
-
-#include "RDFRegisters.h"
-#include "llvm/ADT/BitVector.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/MC/LaneBitmask.h"
-#include "llvm/Support/Allocator.h"
-#include "llvm/Support/MathExtras.h"
-#include "llvm/Support/raw_ostream.h"
-#include "llvm/Target/TargetRegisterInfo.h"
-#include <cassert>
-#include <cstdint>
-#include <cstring>
-#include <functional>
-#include <map>
-#include <set>
-#include <unordered_map>
-#include <utility>
-#include <vector>
-
-// RDF uses uint32_t to refer to registers. This is to ensure that the type
-// size remains specific. In other places, registers are often stored using
-// unsigned.
-static_assert(sizeof(uint32_t) == sizeof(unsigned), "Those should be equal");
-
-namespace llvm {
-
-  class MachineBasicBlock;
-  class MachineFunction;
-  class MachineInstr;
-  class MachineOperand;
-  class MachineDominanceFrontier;
-  class MachineDominatorTree;
-  class TargetInstrInfo;
-
-namespace rdf {
-
-  typedef uint32_t NodeId;
-
-  struct DataFlowGraph;
-
-  struct NodeAttrs {
-    enum : uint16_t {
-      None          = 0x0000,   // Nothing
-
-      // Types: 2 bits
-      TypeMask      = 0x0003,
-      Code          = 0x0001,   // 01, Container
-      Ref           = 0x0002,   // 10, Reference
-
-      // Kind: 3 bits
-      KindMask      = 0x0007 << 2,
-      Def           = 0x0001 << 2,  // 001
-      Use           = 0x0002 << 2,  // 010
-      Phi           = 0x0003 << 2,  // 011
-      Stmt          = 0x0004 << 2,  // 100
-      Block         = 0x0005 << 2,  // 101
-      Func          = 0x0006 << 2,  // 110
-
-      // Flags: 7 bits for now
-      FlagMask      = 0x007F << 5,
-      Shadow        = 0x0001 << 5,  // 0000001, Has extra reaching defs.
-      Clobbering    = 0x0002 << 5,  // 0000010, Produces unspecified values.
-      PhiRef        = 0x0004 << 5,  // 0000100, Member of PhiNode.
-      Preserving    = 0x0008 << 5,  // 0001000, Def can keep original bits.
-      Fixed         = 0x0010 << 5,  // 0010000, Fixed register.
-      Undef         = 0x0020 << 5,  // 0100000, Has no pre-existing value.
-      Dead          = 0x0040 << 5,  // 1000000, Does not define a value.
-    };
-
-    static uint16_t type(uint16_t T)  { return T & TypeMask; }
-    static uint16_t kind(uint16_t T)  { return T & KindMask; }
-    static uint16_t flags(uint16_t T) { return T & FlagMask; }
-
-    static uint16_t set_type(uint16_t A, uint16_t T) {
-      return (A & ~TypeMask) | T;
-    }
-
-    static uint16_t set_kind(uint16_t A, uint16_t K) {
-      return (A & ~KindMask) | K;
-    }
-
-    static uint16_t set_flags(uint16_t A, uint16_t F) {
-      return (A & ~FlagMask) | F;
-    }
-
-    // Test if A contains B.
-    static bool contains(uint16_t A, uint16_t B) {
-      if (type(A) != Code)
-        return false;
-      uint16_t KB = kind(B);
-      switch (kind(A)) {
-        case Func:
-          return KB == Block;
-        case Block:
-          return KB == Phi || KB == Stmt;
-        case Phi:
-        case Stmt:
-          return type(B) == Ref;
-      }
-      return false;
-    }
-  };
-
-  struct BuildOptions {
-    enum : unsigned {
-      None          = 0x00,
-      KeepDeadPhis  = 0x01,   // Do not remove dead phis during build.
-    };
-  };
-
-  template <typename T> struct NodeAddr {
-    NodeAddr() : Addr(nullptr) {}
-    NodeAddr(T A, NodeId I) : Addr(A), Id(I) {}
-
-    // Type cast (casting constructor). The reason for having this class
-    // instead of std::pair.
-    template <typename S> NodeAddr(const NodeAddr<S> &NA)
-      : Addr(static_cast<T>(NA.Addr)), Id(NA.Id) {}
-
-    bool operator== (const NodeAddr<T> &NA) const {
-      assert((Addr == NA.Addr) == (Id == NA.Id));
-      return Addr == NA.Addr;
-    }
-    bool operator!= (const NodeAddr<T> &NA) const {
-      return !operator==(NA);
-    }
-
-    T Addr;
-    NodeId Id = 0;
-  };
-
-  struct NodeBase;
-
-  // Fast memory allocation and translation between node id and node address.
-  // This is really the same idea as the one underlying the "bump pointer
-  // allocator", the difference being in the translation. A node id is
-  // composed of two components: the index of the block in which it was
-  // allocated, and the index within the block. With the default settings,
-  // where the number of nodes per block is 4096, the node id (minus 1) is:
-  //
-  // bit position:                11             0
-  // +----------------------------+--------------+
-  // | Index of the block         |Index in block|
-  // +----------------------------+--------------+
-  //
-  // The actual node id is the above plus 1, to avoid creating a node id of 0.
-  //
-  // This method significantly improved the build time, compared to using maps
-  // (std::unordered_map or DenseMap) to translate between pointers and ids.
-  struct NodeAllocator {
-    // Amount of storage for a single node.
-    enum { NodeMemSize = 32 };
-
-    NodeAllocator(uint32_t NPB = 4096)
-        : NodesPerBlock(NPB), BitsPerIndex(Log2_32(NPB)),
-          IndexMask((1 << BitsPerIndex)-1) {
-      assert(isPowerOf2_32(NPB));
-    }
-
-    NodeBase *ptr(NodeId N) const {
-      uint32_t N1 = N-1;
-      uint32_t BlockN = N1 >> BitsPerIndex;
-      uint32_t Offset = (N1 & IndexMask) * NodeMemSize;
-      return reinterpret_cast<NodeBase*>(Blocks[BlockN]+Offset);
-    }
-
-    NodeId id(const NodeBase *P) const;
-    NodeAddr<NodeBase*> New();
-    void clear();
-
-  private:
-    void startNewBlock();
-    bool needNewBlock();
-
-    uint32_t makeId(uint32_t Block, uint32_t Index) const {
-      // Add 1 to the id, to avoid the id of 0, which is treated as "null".
-      return ((Block << BitsPerIndex) | Index) + 1;
-    }
-
-    const uint32_t NodesPerBlock;
-    const uint32_t BitsPerIndex;
-    const uint32_t IndexMask;
-    char *ActiveEnd = nullptr;
-    std::vector<char*> Blocks;
-    typedef BumpPtrAllocatorImpl<MallocAllocator, 65536> AllocatorTy;
-    AllocatorTy MemPool;
-  };
-
-  typedef std::set<RegisterRef> RegisterSet;
-
-  struct TargetOperandInfo {
-    TargetOperandInfo(const TargetInstrInfo &tii) : TII(tii) {}
-    virtual ~TargetOperandInfo() = default;
-
-    virtual bool isPreserving(const MachineInstr &In, unsigned OpNum) const;
-    virtual bool isClobbering(const MachineInstr &In, unsigned OpNum) const;
-    virtual bool isFixedReg(const MachineInstr &In, unsigned OpNum) const;
-
-    const TargetInstrInfo &TII;
-  };
-
-  // Packed register reference. Only used for storage.
-  struct PackedRegisterRef {
-    RegisterId Reg;
-    uint32_t MaskId;
-  };
-
-  struct LaneMaskIndex : private IndexedSet<LaneBitmask> {
-    LaneMaskIndex() = default;
-
-    LaneBitmask getLaneMaskForIndex(uint32_t K) const {
-      return K == 0 ? LaneBitmask::getAll() : get(K);
-    }
-    uint32_t getIndexForLaneMask(LaneBitmask LM) {
-      assert(LM.any());
-      return LM.all() ? 0 : insert(LM);
-    }
-    uint32_t getIndexForLaneMask(LaneBitmask LM) const {
-      assert(LM.any());
-      return LM.all() ? 0 : find(LM);
-    }
-  };
-
-  struct NodeBase {
-  public:
-    // Make sure this is a POD.
-    NodeBase() = default;
-
-    uint16_t getType()  const { return NodeAttrs::type(Attrs); }
-    uint16_t getKind()  const { return NodeAttrs::kind(Attrs); }
-    uint16_t getFlags() const { return NodeAttrs::flags(Attrs); }
-    NodeId   getNext()  const { return Next; }
-
-    uint16_t getAttrs() const { return Attrs; }
-    void setAttrs(uint16_t A) { Attrs = A; }
-    void setFlags(uint16_t F) { setAttrs(NodeAttrs::set_flags(getAttrs(), F)); }
-
-    // Insert node NA after "this" in the circular chain.
-    void append(NodeAddr<NodeBase*> NA);
-    // Initialize all members to 0.
-    void init() { memset(this, 0, sizeof *this); }
-    void setNext(NodeId N) { Next = N; }
-
-  protected:
-    uint16_t Attrs;
-    uint16_t Reserved;
-    NodeId Next;                // Id of the next node in the circular chain.
-    // Definitions of nested types. Using anonymous nested structs would make
-    // this class definition clearer, but unnamed structs are not a part of
-    // the standard.
-    struct Def_struct  {
-      NodeId DD, DU;          // Ids of the first reached def and use.
-    };
-    struct PhiU_struct  {
-      NodeId PredB;           // Id of the predecessor block for a phi use.
-    };
-    struct Code_struct {
-      void *CP;               // Pointer to the actual code.
-      NodeId FirstM, LastM;   // Id of the first member and last.
-    };
-    struct Ref_struct {
-      NodeId RD, Sib;         // Ids of the reaching def and the sibling.
-      union {
-        Def_struct Def;
-        PhiU_struct PhiU;
-      };
-      union {
-        MachineOperand *Op;   // Non-phi refs point to a machine operand.
-        PackedRegisterRef PR; // Phi refs store register info directly.
-      };
-    };
-
-    // The actual payload.
-    union {
-      Ref_struct Ref;
-      Code_struct Code;
-    };
-  };
-  // The allocator allocates chunks of 32 bytes for each node. The fact that
-  // each node takes 32 bytes in memory is used for fast translation between
-  // the node id and the node address.
-  static_assert(sizeof(NodeBase) <= NodeAllocator::NodeMemSize,
-        "NodeBase must be at most NodeAllocator::NodeMemSize bytes");
-
-  typedef std::vector<NodeAddr<NodeBase*>> NodeList;
-  typedef std::set<NodeId> NodeSet;
-
-  struct RefNode : public NodeBase {
-    RefNode() = default;
-
-    RegisterRef getRegRef(const DataFlowGraph &G) const;
-
-    MachineOperand &getOp() {
-      assert(!(getFlags() & NodeAttrs::PhiRef));
-      return *Ref.Op;
-    }
-
-    void setRegRef(RegisterRef RR, DataFlowGraph &G);
-    void setRegRef(MachineOperand *Op, DataFlowGraph &G);
-
-    NodeId getReachingDef() const {
-      return Ref.RD;
-    }
-    void setReachingDef(NodeId RD) {
-      Ref.RD = RD;
-    }
-
-    NodeId getSibling() const {
-      return Ref.Sib;
-    }
-    void setSibling(NodeId Sib) {
-      Ref.Sib = Sib;
-    }
-
-    bool isUse() const {
-      assert(getType() == NodeAttrs::Ref);
-      return getKind() == NodeAttrs::Use;
-    }
-
-    bool isDef() const {
-      assert(getType() == NodeAttrs::Ref);
-      return getKind() == NodeAttrs::Def;
-    }
-
-    template <typename Predicate>
-    NodeAddr<RefNode*> getNextRef(RegisterRef RR, Predicate P, bool NextOnly,
-        const DataFlowGraph &G);
-    NodeAddr<NodeBase*> getOwner(const DataFlowGraph &G);
-  };
-
-  struct DefNode : public RefNode {
-    NodeId getReachedDef() const {
-      return Ref.Def.DD;
-    }
-    void setReachedDef(NodeId D) {
-      Ref.Def.DD = D;
-    }
-    NodeId getReachedUse() const {
-      return Ref.Def.DU;
-    }
-    void setReachedUse(NodeId U) {
-      Ref.Def.DU = U;
-    }
-
-    void linkToDef(NodeId Self, NodeAddr<DefNode*> DA);
-  };
-
-  struct UseNode : public RefNode {
-    void linkToDef(NodeId Self, NodeAddr<DefNode*> DA);
-  };
-
-  struct PhiUseNode : public UseNode {
-    NodeId getPredecessor() const {
-      assert(getFlags() & NodeAttrs::PhiRef);
-      return Ref.PhiU.PredB;
-    }
-    void setPredecessor(NodeId B) {
-      assert(getFlags() & NodeAttrs::PhiRef);
-      Ref.PhiU.PredB = B;
-    }
-  };
-
-  struct CodeNode : public NodeBase {
-    template <typename T> T getCode() const {
-      return static_cast<T>(Code.CP);
-    }
-    void setCode(void *C) {
-      Code.CP = C;
-    }
-
-    NodeAddr<NodeBase*> getFirstMember(const DataFlowGraph &G) const;
-    NodeAddr<NodeBase*> getLastMember(const DataFlowGraph &G) const;
-    void addMember(NodeAddr<NodeBase*> NA, const DataFlowGraph &G);
-    void addMemberAfter(NodeAddr<NodeBase*> MA, NodeAddr<NodeBase*> NA,
-        const DataFlowGraph &G);
-    void removeMember(NodeAddr<NodeBase*> NA, const DataFlowGraph &G);
-
-    NodeList members(const DataFlowGraph &G) const;
-    template <typename Predicate>
-    NodeList members_if(Predicate P, const DataFlowGraph &G) const;
-  };
-
-  struct InstrNode : public CodeNode {
-    NodeAddr<NodeBase*> getOwner(const DataFlowGraph &G);
-  };
-
-  struct PhiNode : public InstrNode {
-    MachineInstr *getCode() const {
-      return nullptr;
-    }
-  };
-
-  struct StmtNode : public InstrNode {
-    MachineInstr *getCode() const {
-      return CodeNode::getCode<MachineInstr*>();
-    }
-  };
-
-  struct BlockNode : public CodeNode {
-    MachineBasicBlock *getCode() const {
-      return CodeNode::getCode<MachineBasicBlock*>();
-    }
-
-    void addPhi(NodeAddr<PhiNode*> PA, const DataFlowGraph &G);
-  };
-
-  struct FuncNode : public CodeNode {
-    MachineFunction *getCode() const {
-      return CodeNode::getCode<MachineFunction*>();
-    }
-
-    NodeAddr<BlockNode*> findBlock(const MachineBasicBlock *BB,
-        const DataFlowGraph &G) const;
-    NodeAddr<BlockNode*> getEntryBlock(const DataFlowGraph &G);
-  };
-
-  struct DataFlowGraph {
-    DataFlowGraph(MachineFunction &mf, const TargetInstrInfo &tii,
-        const TargetRegisterInfo &tri, const MachineDominatorTree &mdt,
-        const MachineDominanceFrontier &mdf, const TargetOperandInfo &toi);
-
-    NodeBase *ptr(NodeId N) const;
-    template <typename T> T ptr(NodeId N) const {
-      return static_cast<T>(ptr(N));
-    }
-
-    NodeId id(const NodeBase *P) const;
-
-    template <typename T> NodeAddr<T> addr(NodeId N) const {
-      return { ptr<T>(N), N };
-    }
-
-    NodeAddr<FuncNode*> getFunc() const { return Func; }
-    MachineFunction &getMF() const { return MF; }
-    const TargetInstrInfo &getTII() const { return TII; }
-    const TargetRegisterInfo &getTRI() const { return TRI; }
-    const PhysicalRegisterInfo &getPRI() const { return PRI; }
-    const MachineDominatorTree &getDT() const { return MDT; }
-    const MachineDominanceFrontier &getDF() const { return MDF; }
-    const RegisterAggr &getLiveIns() const { return LiveIns; }
-
-    struct DefStack {
-      DefStack() = default;
-
-      bool empty() const { return Stack.empty() || top() == bottom(); }
-
-    private:
-      typedef NodeAddr<DefNode*> value_type;
-      struct Iterator {
-        typedef DefStack::value_type value_type;
-
-        Iterator &up() { Pos = DS.nextUp(Pos); return *this; }
-        Iterator &down() { Pos = DS.nextDown(Pos); return *this; }
-
-        value_type operator*() const {
-          assert(Pos >= 1);
-          return DS.Stack[Pos-1];
-        }
-        const value_type *operator->() const {
-          assert(Pos >= 1);
-          return &DS.Stack[Pos-1];
-        }
-        bool operator==(const Iterator &It) const { return Pos == It.Pos; }
-        bool operator!=(const Iterator &It) const { return Pos != It.Pos; }
-
-      private:
-        Iterator(const DefStack &S, bool Top);
-
-        // Pos-1 is the index in the StorageType object that corresponds to
-        // the top of the DefStack.
-        const DefStack &DS;
-        unsigned Pos;
-        friend struct DefStack;
-      };
-
-    public:
-      typedef Iterator iterator;
-      iterator top() const { return Iterator(*this, true); }
-      iterator bottom() const { return Iterator(*this, false); }
-      unsigned size() const;
-
-      void push(NodeAddr<DefNode*> DA) { Stack.push_back(DA); }
-      void pop();
-      void start_block(NodeId N);
-      void clear_block(NodeId N);
-
-    private:
-      friend struct Iterator;
-      typedef std::vector<value_type> StorageType;
-
-      bool isDelimiter(const StorageType::value_type &P, NodeId N = 0) const {
-        return (P.Addr == nullptr) && (N == 0 || P.Id == N);
-      }
-
-      unsigned nextUp(unsigned P) const;
-      unsigned nextDown(unsigned P) const;
-
-      StorageType Stack;
-    };
-
-    // Make this std::unordered_map for speed of accessing elements.
-    // Map: Register (physical or virtual) -> DefStack
-    typedef std::unordered_map<RegisterId,DefStack> DefStackMap;
-
-    void build(unsigned Options = BuildOptions::None);
-    void pushAllDefs(NodeAddr<InstrNode*> IA, DefStackMap &DM);
-    void markBlock(NodeId B, DefStackMap &DefM);
-    void releaseBlock(NodeId B, DefStackMap &DefM);
-
-    PackedRegisterRef pack(RegisterRef RR) {
-      return { RR.Reg, LMI.getIndexForLaneMask(RR.Mask) };
-    }
-    PackedRegisterRef pack(RegisterRef RR) const {
-      return { RR.Reg, LMI.getIndexForLaneMask(RR.Mask) };
-    }
-    RegisterRef unpack(PackedRegisterRef PR) const {
-      return RegisterRef(PR.Reg, LMI.getLaneMaskForIndex(PR.MaskId));
-    }
-
-    RegisterRef makeRegRef(unsigned Reg, unsigned Sub) const;
-    RegisterRef makeRegRef(const MachineOperand &Op) const;
-    RegisterRef restrictRef(RegisterRef AR, RegisterRef BR) const;
-
-    NodeAddr<RefNode*> getNextRelated(NodeAddr<InstrNode*> IA,
-        NodeAddr<RefNode*> RA) const;
-    NodeAddr<RefNode*> getNextImp(NodeAddr<InstrNode*> IA,
-        NodeAddr<RefNode*> RA, bool Create);
-    NodeAddr<RefNode*> getNextImp(NodeAddr<InstrNode*> IA,
-        NodeAddr<RefNode*> RA) const;
-    NodeAddr<RefNode*> getNextShadow(NodeAddr<InstrNode*> IA,
-        NodeAddr<RefNode*> RA, bool Create);
-    NodeAddr<RefNode*> getNextShadow(NodeAddr<InstrNode*> IA,
-        NodeAddr<RefNode*> RA) const;
-
-    NodeList getRelatedRefs(NodeAddr<InstrNode*> IA,
-        NodeAddr<RefNode*> RA) const;
-
-    NodeAddr<BlockNode*> findBlock(MachineBasicBlock *BB) const {
-      return BlockNodes.at(BB);
-    }
-
-    void unlinkUse(NodeAddr<UseNode*> UA, bool RemoveFromOwner) {
-      unlinkUseDF(UA);
-      if (RemoveFromOwner)
-        removeFromOwner(UA);
-    }
-
-    void unlinkDef(NodeAddr<DefNode*> DA, bool RemoveFromOwner) {
-      unlinkDefDF(DA);
-      if (RemoveFromOwner)
-        removeFromOwner(DA);
-    }
-
-    // Some useful filters.
-    template <uint16_t Kind>
-    static bool IsRef(const NodeAddr<NodeBase*> BA) {
-      return BA.Addr->getType() == NodeAttrs::Ref &&
-             BA.Addr->getKind() == Kind;
-    }
-
-    template <uint16_t Kind>
-    static bool IsCode(const NodeAddr<NodeBase*> BA) {
-      return BA.Addr->getType() == NodeAttrs::Code &&
-             BA.Addr->getKind() == Kind;
-    }
-
-    static bool IsDef(const NodeAddr<NodeBase*> BA) {
-      return BA.Addr->getType() == NodeAttrs::Ref &&
-             BA.Addr->getKind() == NodeAttrs::Def;
-    }
-
-    static bool IsUse(const NodeAddr<NodeBase*> BA) {
-      return BA.Addr->getType() == NodeAttrs::Ref &&
-             BA.Addr->getKind() == NodeAttrs::Use;
-    }
-
-    static bool IsPhi(const NodeAddr<NodeBase*> BA) {
-      return BA.Addr->getType() == NodeAttrs::Code &&
-             BA.Addr->getKind() == NodeAttrs::Phi;
-    }
-
-    static bool IsPreservingDef(const NodeAddr<DefNode*> DA) {
-      uint16_t Flags = DA.Addr->getFlags();
-      return (Flags & NodeAttrs::Preserving) && !(Flags & NodeAttrs::Undef);
-    }
-
-  private:
-    void reset();
-
-    RegisterSet getLandingPadLiveIns() const;
-
-    NodeAddr<NodeBase*> newNode(uint16_t Attrs);
-    NodeAddr<NodeBase*> cloneNode(const NodeAddr<NodeBase*> B);
-    NodeAddr<UseNode*> newUse(NodeAddr<InstrNode*> Owner,
-        MachineOperand &Op, uint16_t Flags = NodeAttrs::None);
-    NodeAddr<PhiUseNode*> newPhiUse(NodeAddr<PhiNode*> Owner,
-        RegisterRef RR, NodeAddr<BlockNode*> PredB,
-        uint16_t Flags = NodeAttrs::PhiRef);
-    NodeAddr<DefNode*> newDef(NodeAddr<InstrNode*> Owner,
-        MachineOperand &Op, uint16_t Flags = NodeAttrs::None);
-    NodeAddr<DefNode*> newDef(NodeAddr<InstrNode*> Owner,
-        RegisterRef RR, uint16_t Flags = NodeAttrs::PhiRef);
-    NodeAddr<PhiNode*> newPhi(NodeAddr<BlockNode*> Owner);
-    NodeAddr<StmtNode*> newStmt(NodeAddr<BlockNode*> Owner,
-        MachineInstr *MI);
-    NodeAddr<BlockNode*> newBlock(NodeAddr<FuncNode*> Owner,
-        MachineBasicBlock *BB);
-    NodeAddr<FuncNode*> newFunc(MachineFunction *MF);
-
-    template <typename Predicate>
-    std::pair<NodeAddr<RefNode*>,NodeAddr<RefNode*>>
-    locateNextRef(NodeAddr<InstrNode*> IA, NodeAddr<RefNode*> RA,
-        Predicate P) const;
-
-    typedef std::map<NodeId,RegisterSet> BlockRefsMap;
-
-    void buildStmt(NodeAddr<BlockNode*> BA, MachineInstr &In);
-    void buildBlockRefs(NodeAddr<BlockNode*> BA, BlockRefsMap &RefM);
-    void recordDefsForDF(BlockRefsMap &PhiM, BlockRefsMap &RefM,
-        NodeAddr<BlockNode*> BA);
-    void buildPhis(BlockRefsMap &PhiM, BlockRefsMap &RefM,
-        NodeAddr<BlockNode*> BA);
-    void removeUnusedPhis();
-
-    void pushClobbers(NodeAddr<InstrNode*> IA, DefStackMap &DM);
-    void pushDefs(NodeAddr<InstrNode*> IA, DefStackMap &DM);
-    template <typename T> void linkRefUp(NodeAddr<InstrNode*> IA,
-        NodeAddr<T> TA, DefStack &DS);
-    template <typename Predicate> void linkStmtRefs(DefStackMap &DefM,
-        NodeAddr<StmtNode*> SA, Predicate P);
-    void linkBlockRefs(DefStackMap &DefM, NodeAddr<BlockNode*> BA);
-
-    void unlinkUseDF(NodeAddr<UseNode*> UA);
-    void unlinkDefDF(NodeAddr<DefNode*> DA);
-
-    void removeFromOwner(NodeAddr<RefNode*> RA) {
-      NodeAddr<InstrNode*> IA = RA.Addr->getOwner(*this);
-      IA.Addr->removeMember(RA, *this);
-    }
-
-    MachineFunction &MF;
-    const TargetInstrInfo &TII;
-    const TargetRegisterInfo &TRI;
-    const PhysicalRegisterInfo PRI;
-    const MachineDominatorTree &MDT;
-    const MachineDominanceFrontier &MDF;
-    const TargetOperandInfo &TOI;
-
-    RegisterAggr LiveIns;
-    NodeAddr<FuncNode*> Func;
-    NodeAllocator Memory;
-    // Local map:  MachineBasicBlock -> NodeAddr<BlockNode*>
-    std::map<MachineBasicBlock*,NodeAddr<BlockNode*>> BlockNodes;
-    // Lane mask map.
-    LaneMaskIndex LMI;
-  };  // struct DataFlowGraph
-
-  template <typename Predicate>
-  NodeAddr<RefNode*> RefNode::getNextRef(RegisterRef RR, Predicate P,
-        bool NextOnly, const DataFlowGraph &G) {
-    // Get the "Next" reference in the circular list that references RR and
-    // satisfies predicate "Pred".
-    auto NA = G.addr<NodeBase*>(getNext());
-
-    while (NA.Addr != this) {
-      if (NA.Addr->getType() == NodeAttrs::Ref) {
-        NodeAddr<RefNode*> RA = NA;
-        if (RA.Addr->getRegRef(G) == RR && P(NA))
-          return NA;
-        if (NextOnly)
-          break;
-        NA = G.addr<NodeBase*>(NA.Addr->getNext());
-      } else {
-        // We've hit the beginning of the chain.
-        assert(NA.Addr->getType() == NodeAttrs::Code);
-        NodeAddr<CodeNode*> CA = NA;
-        NA = CA.Addr->getFirstMember(G);
-      }
-    }
-    // Return the equivalent of "nullptr" if such a node was not found.
-    return NodeAddr<RefNode*>();
-  }
-
-  template <typename Predicate>
-  NodeList CodeNode::members_if(Predicate P, const DataFlowGraph &G) const {
-    NodeList MM;
-    auto M = getFirstMember(G);
-    if (M.Id == 0)
-      return MM;
-
-    while (M.Addr != this) {
-      if (P(M))
-        MM.push_back(M);
-      M = G.addr<NodeBase*>(M.Addr->getNext());
-    }
-    return MM;
-  }
-
-
-  template <typename T> struct Print;
-  template <typename T>
-  raw_ostream &operator<< (raw_ostream &OS, const Print<T> &P);
-
-  template <typename T>
-  struct Print {
-    Print(const T &x, const DataFlowGraph &g) : Obj(x), G(g) {}
-    const T &Obj;
-    const DataFlowGraph &G;
-  };
-
-  template <typename T>
-  struct PrintNode : Print<NodeAddr<T>> {
-    PrintNode(const NodeAddr<T> &x, const DataFlowGraph &g)
-      : Print<NodeAddr<T>>(x, g) {}
-  };
-
-} // end namespace rdf
-
-} // end namespace llvm
-
-#endif // LLVM_LIB_TARGET_HEXAGON_RDFGRAPH_H

lib/Target/Hexagon/RDFGraph.cpp

-//===--- RDFGraph.cpp -----------------------------------------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// Target-independent, SSA-based data flow graph for register data flow (RDF).
-//
-#include "RDFGraph.h"
-#include "llvm/ADT/SetVector.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/CodeGen/MachineBasicBlock.h"
-#include "llvm/CodeGen/MachineDominanceFrontier.h"
-#include "llvm/CodeGen/MachineDominators.h"
-#include "llvm/CodeGen/MachineFunction.h"
-#include "llvm/CodeGen/MachineInstr.h"
-#include "llvm/CodeGen/MachineOperand.h"
-#include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/IR/Function.h"
-#include "llvm/MC/LaneBitmask.h"
-#include "llvm/MC/MCInstrDesc.h"
-#include "llvm/MC/MCRegisterInfo.h"
-#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/raw_ostream.h"
-#include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Target/TargetLowering.h"
-#include "llvm/Target/TargetRegisterInfo.h"
-#include <algorithm>
-#include <cassert>
-#include <cstdint>
-#include <cstring>
-#include <iterator>
-#include <utility>
-#include <vector>
-
-using namespace llvm;
-using namespace rdf;
-
-// Printing functions. Have them here first, so that the rest of the code
-// can use them.
-namespace llvm {
-namespace rdf {
-
-raw_ostream &operator<< (raw_ostream &OS, const PrintLaneMaskOpt &P) {
-  if (!P.Mask.all())
-    OS << ':' << PrintLaneMask(P.Mask);
-  return OS;
-}
-
-template<>
-raw_ostream &operator<< (raw_ostream &OS, const Print<RegisterRef> &P) {
-  auto &TRI = P.G.getTRI();
-  if (P.Obj.Reg > 0 && P.Obj.Reg < TRI.getNumRegs())
-    OS << TRI.getName(P.Obj.Reg);
-  else
-    OS << '#' << P.Obj.Reg;
-  OS << PrintLaneMaskOpt(P.Obj.Mask);
-  return OS;
-}
-
-template<>
-raw_ostream &operator<< (raw_ostream &OS, const Print<NodeId> &P) {
-  auto NA = P.G.addr<NodeBase*>(P.Obj);
-  uint16_t Attrs = NA.Addr->getAttrs();
-  uint16_t Kind = NodeAttrs::kind(Attrs);
-  uint16_t Flags = NodeAttrs::flags(Attrs);
-  switch (NodeAttrs::type(Attrs)) {
-    case NodeAttrs::Code:
-      switch (Kind) {
-        case NodeAttrs::Func:   OS << 'f'; break;
-        case NodeAttrs::Block:  OS << 'b'; break;
-        case NodeAttrs::Stmt:   OS << 's'; break;
-        case NodeAttrs::Phi:    OS << 'p'; break;
-        default:                OS << "c?"; break;
-      }
-      break;
-    case NodeAttrs::Ref:
-      if (Flags & NodeAttrs::Undef)
-        OS << '/';
-      if (Flags & NodeAttrs::Dead)
-        OS << '\\';
-      if (Flags & NodeAttrs::Preserving)
-        OS << '+';
-      if (Flags & NodeAttrs::Clobbering)
-        OS << '~';
-      switch (Kind) {
-        case NodeAttrs::Use:    OS << 'u'; break;
-        case NodeAttrs::Def:    OS << 'd'; break;
-        case NodeAttrs::Block:  OS << 'b'; break;
-        default:                OS << "r?"; break;
-      }
-      break;
-    default:
-      OS << '?';
-      break;
-  }
-  OS << P.Obj;
-  if (Flags & NodeAttrs::Shadow)
-    OS << '"';
-  return OS;
-}
-
-static void printRefHeader(raw_ostream &OS, const NodeAddr<RefNode*> RA,
-                const DataFlowGraph &G) {
-  OS << Print<NodeId>(RA.Id, G) << '<'
-     << Print<RegisterRef>(RA.Addr->getRegRef(G), G) << '>';
-  if (RA.Addr->getFlags() & NodeAttrs::Fixed)
-    OS << '!';
-}
-
-template<>
-raw_ostream &operator<< (raw_ostream &OS, const Print<NodeAddr<DefNode*>> &P) {
-  printRefHeader(OS, P.Obj, P.G);
-  OS << '(';
-  if (NodeId N = P.Obj.Addr->getReachingDef())
-    OS << Print<NodeId>(N, P.G);
-  OS << ',';
-  if (NodeId N = P.Obj.Addr->getReachedDef())
-    OS << Print<NodeId>(N, P.G);
-  OS << ',';
-  if (NodeId N = P.Obj.Addr->getReachedUse())
-    OS << Print<NodeId>(N, P.G);
-  OS << "):";
-  if (NodeId N = P.Obj.Addr->getSibling())
-    OS << Print<NodeId>(N, P.G);
-  return OS;
-}
-
-template<>
-raw_ostream &operator<< (raw_ostream &OS, const Print<NodeAddr<UseNode*>> &P) {
-  printRefHeader(OS, P.Obj, P.G);
-  OS << '(';
-  if (NodeId N = P.Obj.Addr->getReachingDef())
-    OS << Print<NodeId>(N, P.G);
-  OS << "):";
-  if (NodeId N = P.Obj.Addr->getSibling())
-    OS << Print<NodeId>(N, P.G);
-  return OS;
-}
-
-template<>
-raw_ostream &operator<< (raw_ostream &OS,
-      const Print<NodeAddr<PhiUseNode*>> &P) {
-  printRefHeader(OS, P.Obj, P.G);
-  OS << '(';
-  if (NodeId N = P.Obj.Addr->getReachingDef())
-    OS << Print<NodeId>(N, P.G);
-  OS << ',';
-  if (NodeId N = P.Obj.Addr->getPredecessor())
-    OS << Print<NodeId>(N, P.G);
-  OS << "):";
-  if (NodeId N = P.Obj.Addr->getSibling())
-    OS << Print<NodeId>(N, P.G);
-  return OS;
-}
-
-template<>
-raw_ostream &operator<< (raw_ostream &OS, const Print<NodeAddr<RefNode*>> &P) {
-  switch (P.Obj.Addr->getKind()) {
-    case NodeAttrs::Def:
-      OS << PrintNode<DefNode*>(P.Obj, P.G);
-      break;
-    case NodeAttrs::Use:
-      if (P.Obj.Addr->getFlags() & NodeAttrs::PhiRef)
-        OS << PrintNode<PhiUseNode*>(P.Obj, P.G);
-      else
-        OS << PrintNode<UseNode*>(P.Obj, P.G);
-      break;
-  }
-  return OS;
-}
-
-template<>
-raw_ostream &operator<< (raw_ostream &OS, const Print<NodeList> &P) {
-  unsigned N = P.Obj.size();
-  for (auto I : P.Obj) {
-    OS << Print<NodeId>(I.Id, P.G);
-    if (--N)
-      OS << ' ';
-  }
-  return OS;
-}
-
-template<>
-raw_ostream &operator<< (raw_ostream &OS, const Print<NodeSet> &P) {
-  unsigned N = P.Obj.size();
-  for (auto I : P.Obj) {
-    OS << Print<NodeId>(I, P.G);
-    if (--N)
-      OS << ' ';
-  }
-  return OS;
-}
-
-namespace {
-
-  template <typename T>
-  struct PrintListV {
-    PrintListV(const NodeList &L, const DataFlowGraph &G) : List(L), G(G) {}
-
-    typedef T Type;
-    const NodeList &List;
-    const DataFlowGraph &G;
-  };
-
-  template <typename T>
-  raw_ostream &operator<< (raw_ostream &OS, const PrintListV<T> &P) {
-    unsigned N = P.List.size();
-    for (NodeAddr<T> A : P.List) {
-      OS << PrintNode<T>(A, P.G);
-      if (--N)
-        OS << ", ";
-    }
-    return OS;
-  }
-
-} // end anonymous namespace
-
-template<>
-raw_ostream &operator<< (raw_ostream &OS, const Print<NodeAddr<PhiNode*>> &P) {
-  OS << Print<NodeId>(P.Obj.Id, P.G) << ": phi ["
-     << PrintListV<RefNode*>(P.Obj.Addr->members(P.G), P.G) << ']';
-  return OS;
-}
-
-template<>
-raw_ostream &operator<< (raw_ostream &OS,
-      const Print<NodeAddr<StmtNode*>> &P) {
-  const MachineInstr &MI = *P.Obj.Addr->getCode();
-  unsigned Opc = MI.getOpcode();
-  OS << Print<NodeId>(P.Obj.Id, P.G) << ": " << P.G.getTII().getName(Opc);
-  // Print the target for calls and branches (for readability).
-  if (MI.isCall() || MI.isBranch()) {
-    MachineInstr::const_mop_iterator T =
-          llvm::find_if(MI.operands(),
-                        [] (const MachineOperand &Op) -> bool {
-                          return Op.isMBB() || Op.isGlobal() || Op.isSymbol();
-                        });
-    if (T != MI.operands_end()) {
-      OS << ' ';
-      if (T->isMBB())
-        OS << "BB#" << T->getMBB()->getNumber();
-      else if (T->isGlobal())
-        OS << T->getGlobal()->getName();
-      else if (T->isSymbol())
-        OS << T->getSymbolName();
-    }
-  }
-  OS << " [" << PrintListV<RefNode*>(P.Obj.Addr->members(P.G), P.G) << ']';
-  return OS;
-}
-
-template<>
-raw_ostream &operator<< (raw_ostream &OS,
-      const Print<NodeAddr<InstrNode*>> &P) {
-  switch (P.Obj.Addr->getKind()) {
-    case NodeAttrs::Phi:
-      OS << PrintNode<PhiNode*>(P.Obj, P.G);
-      break;
-    case NodeAttrs::Stmt:
-      OS << PrintNode<StmtNode*>(P.Obj, P.G);
-      break;
-    default:
-      OS << "instr? " << Print<NodeId>(P.Obj.Id, P.G);
-      break;
-  }
-  return OS;
-}
-
-template<>
-raw_ostream &operator<< (raw_ostream &OS,
-      const Print<NodeAddr<BlockNode*>> &P) {
-  MachineBasicBlock *BB = P.Obj.Addr->getCode();
-  unsigned NP = BB->pred_size();
-  std::vector<int> Ns;
-  auto PrintBBs = [&OS] (std::vector<int> Ns) -> void {
-    unsigned N = Ns.size();
-    for (int I : Ns) {
-      OS << "BB#" << I;
-      if (--N)
-        OS << ", ";
-    }
-  };
-
-  OS << Print<NodeId>(P.Obj.Id, P.G) << ": --- BB#" << BB->getNumber()
-     << " --- preds(" << NP << "): ";
-  for (MachineBasicBlock *B : BB->predecessors())
-    Ns.push_back(B->getNumber());
-  PrintBBs(Ns);
-
-  unsigned NS = BB->succ_size();
-  OS << "  succs(" << NS << "): ";
-  Ns.clear();
-  for (MachineBasicBlock *B : BB->successors())
-    Ns.push_back(B->getNumber());
-  PrintBBs(Ns);
-  OS << '\n';
-
-  for (auto I : P.Obj.Addr->members(P.G))
-    OS << PrintNode<InstrNode*>(I, P.G) << '\n';
-  return OS;
-}
-
-template<>
-raw_ostream &operator<< (raw_ostream &OS,
-      const Print<NodeAddr<FuncNode*>> &P) {
-  OS << "DFG dump:[\n" << Print<NodeId>(P.Obj.Id, P.G) << ": Function: "
-     << P.Obj.Addr->getCode()->getName() << '\n';
-  for (auto I : P.Obj.Addr->members(P.G))
-    OS << PrintNode<BlockNode*>(I, P.G) << '\n';
-  OS << "]\n";
-  return OS;
-}
-
-template<>
-raw_ostream &operator<< (raw_ostream &OS, const Print<RegisterSet> &P) {
-  OS << '{';
-  for (auto I : P.Obj)
-    OS << ' ' << Print<RegisterRef>(I, P.G);
-  OS << " }";
-  return OS;
-}
-
-template<>
-raw_ostream &operator<< (raw_ostream &OS, const Print<RegisterAggr> &P) {
-  P.Obj.print(OS);
-  return OS;
-}
-
-template<>
-raw_ostream &operator<< (raw_ostream &OS,
-      const Print<DataFlowGraph::DefStack> &P) {
-  for (auto I = P.Obj.top(), E = P.Obj.bottom(); I != E; ) {
-    OS << Print<NodeId>(I->Id, P.G)
-       << '<' << Print<RegisterRef>(I->Addr->getRegRef(P.G), P.G) << '>';
-    I.down();
-    if (I != E)
-      OS << ' ';
-  }
-  return OS;
-}
-
-} // end namespace rdf
-} // end namespace llvm
-
-// Node allocation functions.
-//
-// Node allocator is like a slab memory allocator: it allocates blocks of
-// memory in sizes that are multiples of the size of a node. Each block has
-// the same size. Nodes are allocated from the currently active block, and
-// when it becomes full, a new one is created.
-// There is a mapping scheme between node id and its location in a block,
-// and within that block is described in the header file.
-//
-void NodeAllocator::startNewBlock() {
-  void *T = MemPool.Allocate(NodesPerBlock*NodeMemSize, NodeMemSize);
-  char *P = static_cast<char*>(T);
-  Blocks.push_back(P);
-  // Check if the block index is still within the allowed range, i.e. less
-  // than 2^N, where N is the number of bits in NodeId for the block index.
-  // BitsPerIndex is the number of bits per node index.
-  assert((Blocks.size() < ((size_t)1 << (8*sizeof(NodeId)-BitsPerIndex))) &&
-         "Out of bits for block index");
-  ActiveEnd = P;
-}
-
-bool NodeAllocator::needNewBlock() {
-  if (Blocks.empty())
-    return true;
-
-  char *ActiveBegin = Blocks.back();
-  uint32_t Index = (ActiveEnd-ActiveBegin)/NodeMemSize;
-  return Index >= NodesPerBlock;
-}
-
-NodeAddr<NodeBase*> NodeAllocator::New() {
-  if (needNewBlock())
-    startNewBlock();
-
-  uint32_t ActiveB = Blocks.size()-1;
-  uint32_t Index = (ActiveEnd - Blocks[ActiveB])/NodeMemSize;
-  NodeAddr<NodeBase*> NA = { reinterpret_cast<NodeBase*>(ActiveEnd),
-                             makeId(ActiveB, Index) };
-  ActiveEnd += NodeMemSize;
-  return NA;
-}
-
-NodeId NodeAllocator::id(const NodeBase *P) const {
-  uintptr_t A = reinterpret_cast<uintptr_t>(P);
-  for (unsigned i = 0, n = Blocks.size(); i != n; ++i) {
-    uintptr_t B = reinterpret_cast<uintptr_t>(Blocks[i]);
-    if (A < B || A >= B + NodesPerBlock*NodeMemSize)
-      continue;
-    uint32_t Idx = (A-B)/NodeMemSize;
-    return makeId(i, Idx);
-  }
-  llvm_unreachable("Invalid node address");
-}
-
-void NodeAllocator::clear() {
-  MemPool.Reset();
-  Blocks.clear();
-  ActiveEnd = nullptr;
-}
-
-// Insert node NA after "this" in the circular chain.
-void NodeBase::append(NodeAddr<NodeBase*> NA) {
-  NodeId Nx = Next;
-  // If NA is already "next", do nothing.
-  if (Next != NA.Id) {
-    Next = NA.Id;
-    NA.Addr->Next = Nx;
-  }
-}
-
-// Fundamental node manipulator functions.
-
-// Obtain the register reference from a reference node.
-RegisterRef RefNode::getRegRef(const DataFlowGraph &G) const {
-  assert(NodeAttrs::type(Attrs) == NodeAttrs::Ref);
-  if (NodeAttrs::flags(Attrs) & NodeAttrs::PhiRef)
-    return G.unpack(Ref.PR);
-  assert(Ref.Op != nullptr);
-  return G.makeRegRef(*Ref.Op);
-}
-
-// Set the register reference in the reference node directly (for references
-// in phi nodes).
-void RefNode::setRegRef(RegisterRef RR, DataFlowGraph &G) {
-  assert(NodeAttrs::type(Attrs) == NodeAttrs::Ref);
-  assert(NodeAttrs::flags(Attrs) & NodeAttrs::PhiRef);
-  Ref.PR = G.pack(RR);
-}
-
-// Set the register reference in the reference node based on a machine
-// operand (for references in statement nodes).
-void RefNode::setRegRef(MachineOperand *Op, DataFlowGraph &G) {
-  assert(NodeAttrs::type(Attrs) == NodeAttrs::Ref);
-  assert(!(NodeAttrs::flags(Attrs) & NodeAttrs::PhiRef));
-  (void)G;
-  Ref.Op = Op;
-}
-
-// Get the owner of a given reference node.
-NodeAddr<NodeBase*> RefNode::getOwner(const DataFlowGraph &G) {
-  NodeAddr<NodeBase*> NA = G.addr<NodeBase*>(getNext());
-
-  while (NA.Addr != this) {
-    if (NA.Addr->getType() == NodeAttrs::Code)
-      return NA;
-    NA = G.addr<NodeBase*>(NA.Addr->getNext());
-  }
-  llvm_unreachable("No owner in circular list");
-}
-
-// Connect the def node to the reaching def node.
-void DefNode::linkToDef(NodeId Self, NodeAddr<DefNode*> DA) {
-  Ref.RD = DA.Id;
-  Ref.Sib = DA.Addr->getReachedDef();
-  DA.Addr->setReachedDef(Self);
-}
-
-// Connect the use node to the reaching def node.
-void UseNode::linkToDef(NodeId Self, NodeAddr<DefNode*> DA) {
-  Ref.RD = DA.Id;
-  Ref.Sib = DA.Addr->getReachedUse();
-  DA.Addr->setReachedUse(Self);
-}
-
-// Get the first member of the code node.
-NodeAddr<NodeBase*> CodeNode::getFirstMember(const DataFlowGraph &G) const {
-  if (Code.FirstM == 0)
-    return NodeAddr<NodeBase*>();
-  return G.addr<NodeBase*>(Code.FirstM);
-}
-
-// Get the last member of the code node.
-NodeAddr<NodeBase*> CodeNode::getLastMember(const DataFlowGraph &G) const {
-  if (Code.LastM == 0)
-    return NodeAddr<NodeBase*>();
-  return G.addr<NodeBase*>(Code.LastM);
-}
-
-// Add node NA at the end of the member list of the given code node.
-void CodeNode::addMember(NodeAddr<NodeBase*> NA, const DataFlowGraph &G) {
-  NodeAddr<NodeBase*> ML = getLastMember(G);
-  if (ML.Id != 0) {
-    ML.Addr->append(NA);
-  } else {
-    Code.FirstM = NA.Id;
-    NodeId Self = G.id(this);
-    NA.Addr->setNext(Self);
-  }
-  Code.LastM = NA.Id;
-}
-
-// Add node NA after member node MA in the given code node.
-void CodeNode::addMemberAfter(NodeAddr<NodeBase*> MA, NodeAddr<NodeBase*> NA,
-      const DataFlowGraph &G) {
-  MA.Addr->append(NA);
-  if (Code.LastM == MA.Id)
-    Code.LastM = NA.Id;
-}
-
-// Remove member node NA from the given code node.
-void CodeNode::removeMember(NodeAddr<NodeBase*> NA, const DataFlowGraph &G) {
-  NodeAddr<NodeBase*> MA = getFirstMember(G);
-  assert(MA.Id != 0);
-
-  // Special handling if the member to remove is the first member.
-  if (MA.Id == NA.Id) {
-    if (Code.LastM == MA.Id) {
-      // If it is the only member, set both first and last to 0.
-      Code.FirstM = Code.LastM = 0;
-    } else {
-      // Otherwise, advance the first member.
-      Code.FirstM = MA.Addr->getNext();
-    }
-    return;
-  }
-
-  while (MA.Addr != this) {
-    NodeId MX = MA.Addr->getNext();
-    if (MX == NA.Id) {
-      MA.Addr->setNext(NA.Addr->getNext());
-      // If the member to remove happens to be the last one, update the
-      // LastM indicator.
-      if (Code.LastM == NA.Id)
-        Code.LastM = MA.Id;
-      return;
-    }
-    MA = G.addr<NodeBase*>(MX);
-  }
-  llvm_unreachable("No such member");
-}
-
-// Return the list of all members of the code node.
-NodeList CodeNode::members(const DataFlowGraph &G) const {
-  static auto True = [] (NodeAddr<NodeBase*>) -> bool { return true; };
-  return members_if(True, G);
-}
-
-// Return the owner of the given instr node.
-NodeAddr<NodeBase*> InstrNode::getOwner(const DataFlowGraph &G) {
-  NodeAddr<NodeBase*> NA = G.addr<NodeBase*>(getNext());
-
-  while (NA.Addr != this) {
-    assert(NA.Addr->getType() == NodeAttrs::Code);
-    if (NA.Addr->getKind() == NodeAttrs::Block)
-      return NA;
-    NA = G.addr<NodeBase*>(NA.Addr->getNext());
-  }
-  llvm_unreachable("No owner in circular list");
-}
-
-// Add the phi node PA to the given block node.
-void BlockNode::addPhi(NodeAddr<PhiNode*> PA, const DataFlowGraph &G) {
-  NodeAddr<NodeBase*> M = getFirstMember(G);
-  if (M.Id == 0) {
-    addMember(PA, G);
-    return;
-  }
-
-  assert(M.Addr->getType() == NodeAttrs::Code);
-  if (M.Addr->getKind() == NodeAttrs::Stmt) {
-    // If the first member of the block is a statement, insert the phi as
-    // the first member.
-    Code.FirstM = PA.Id;
-    PA.Addr->setNext(M.Id);
-  } else {
-    // If the first member is a phi, find the last phi, and append PA to it.
-    assert(M.Addr->getKind() == NodeAttrs::Phi);
-    NodeAddr<NodeBase*> MN = M;
-    do {
-      M = MN;
-      MN = G.addr<NodeBase*>(M.Addr->getNext());
-      assert(MN.Addr->getType() == NodeAttrs::Code);
-    } while (MN.Addr->getKind() == NodeAttrs::Phi);
-
-    // M is the last phi.
-    addMemberAfter(M, PA, G);
-  }
-}
-
-// Find the block node corresponding to the machine basic block BB in the
-// given func node.
-NodeAddr<BlockNode*> FuncNode::findBlock(const MachineBasicBlock *BB,
-      const DataFlowGraph &G) const {
-  auto EqBB = [BB] (NodeAddr<NodeBase*> NA) -> bool {
-    return NodeAddr<BlockNode*>(NA).Addr->getCode() == BB;
-  };
-  NodeList Ms = members_if(EqBB, G);
-  if (!Ms.empty())
-    return Ms[0];
-  return NodeAddr<BlockNode*>();
-}
-
-// Get the block node for the entry block in the given function.
-NodeAddr<BlockNode*> FuncNode::getEntryBlock(const DataFlowGraph &G) {
-  MachineBasicBlock *EntryB = &getCode()->front();
-  return findBlock(EntryB, G);
-}
-
-// Target operand information.
-//
-
-// For a given instruction, check if there are any bits of RR that can remain
-// unchanged across this def.
-bool TargetOperandInfo::isPreserving(const MachineInstr &In, unsigned OpNum)
-      const {
-  return TII.isPredicated(In);
-}
-
-// Check if the definition of RR produces an unspecified value.
-bool TargetOperandInfo::isClobbering(const MachineInstr &In, unsigned OpNum)
-      const {
-  const MachineOperand &Op = In.getOperand(OpNum);
-  if (Op.isRegMask())
-    return true;
-  assert(Op.isReg());
-  if (In.isCall())
-    if (Op.isDef() && Op.isDead())
-      return true;
-  return false;
-}
-
-// Check if the given instruction specifically requires
-bool TargetOperandInfo::isFixedReg(const MachineInstr &In, unsigned OpNum)
-      const {
-  if (In.isCall() || In.isReturn() || In.isInlineAsm())
-    return true;
-  // Check for a tail call.
-  if (In.isBranch())
-    for (const MachineOperand &O : In.operands())
-      if (O.isGlobal() || O.isSymbol())
-        return true;
-
-  const MCInstrDesc &D = In.getDesc();
-  if (!D.getImplicitDefs() && !D.getImplicitUses())
-    return false;
-  const MachineOperand &Op = In.getOperand(OpNum);
-  // If there is a sub-register, treat the operand as non-fixed. Currently,
-  // fixed registers are those that are listed in the descriptor as implicit
-  // uses or defs, and those lists do not allow sub-registers.
-  if (Op.getSubReg() != 0)
-    return false;
-  RegisterId Reg = Op.getReg();
-  const MCPhysReg *ImpR = Op.isDef() ? D.getImplicitDefs()
-                                     : D.getImplicitUses();
-  if (!ImpR)
-    return false;
-  while (*ImpR)
-    if (*ImpR++ == Reg)
-      return true;
-  return false;
-}
-
-//
-// The data flow graph construction.
-//
-
-DataFlowGraph::DataFlowGraph(MachineFunction &mf, const TargetInstrInfo &tii,
-      const TargetRegisterInfo &tri, const MachineDominatorTree &mdt,
-      const MachineDominanceFrontier &mdf, const TargetOperandInfo &toi)
-    : MF(mf), TII(tii), TRI(tri), PRI(tri, mf), MDT(mdt), MDF(mdf), TOI(toi),
-      LiveIns(PRI) {
-}
-
-// The implementation of the definition stack.
-// Each register reference has its own definition stack. In particular,
-// for a register references "Reg" and "Reg:subreg" will each have their
-// own definition stacks.
-
-// Construct a stack iterator.
-DataFlowGraph::DefStack::Iterator::Iterator(const DataFlowGraph::DefStack &S,
-      bool Top) : DS(S) {
-  if (!Top) {
-    // Initialize to bottom.
-    Pos = 0;
-    return;
-  }
-  // Initialize to the top, i.e. top-most non-delimiter (or 0, if empty).
-  Pos = DS.Stack.size();
-  while (Pos > 0 && DS.isDelimiter(DS.Stack[Pos-1]))
-    Pos--;
-}
-
-// Return the size of the stack, including block delimiters.
-unsigned DataFlowGraph::DefStack::size() const {
-  unsigned S = 0;
-  for (auto I = top(), E = bottom(); I != E; I.down())
-    S++;
-  return S;
-}
-
-// Remove the top entry from the stack. Remove all intervening delimiters
-// so that after this, the stack is either empty, or the top of the stack
-// is a non-delimiter.
-void DataFlowGraph::DefStack::pop() {
-  assert(!empty());
-  unsigned P = nextDown(Stack.size());
-  Stack.resize(P);
-}
-
-// Push a delimiter for block node N on the stack.
-void DataFlowGraph::DefStack::start_block(NodeId N) {
-  assert(N != 0);
-  Stack.push_back(NodeAddr<DefNode*>(nullptr, N));
-}
-
-// Remove all nodes from the top of the stack, until the delimited for
-// block node N is encountered. Remove the delimiter as well. In effect,
-// this will remove from the stack all definitions from block N.
-void DataFlowGraph::DefStack::clear_block(NodeId N) {
-  assert(N != 0);
-  unsigned P = Stack.size();
-  while (P > 0) {
-    bool Found = isDelimiter(Stack[P-1], N);
-    P--;
-    if (Found)
-      break;
-  }
-  // This will also remove the delimiter, if found.
-  Stack.resize(P);
-}
-
-// Move the stack iterator up by one.
-unsigned DataFlowGraph::DefStack::nextUp(unsigned P) const {
-  // Get the next valid position after P (skipping all delimiters).
-  // The input position P does not have to point to a non-delimiter.
-  unsigned SS = Stack.size();
-  bool IsDelim;
-  assert(P < SS);
-  do {
-    P++;
-    IsDelim = isDelimiter(Stack[P-1]);
-  } while (P < SS && IsDelim);
-  assert(!IsDelim);
-  return P;
-}
-
-// Move the stack iterator down by one.
-unsigned DataFlowGraph::DefStack::nextDown(unsigned P) const {
-  // Get the preceding valid position before P (skipping all delimiters).
-  // The input position P does not have to point to a non-delimiter.
-  assert(P > 0 && P <= Stack.size());
-  bool IsDelim = isDelimiter(Stack[P-1]);
-  do {
-    if (--P == 0)
-      break;
-    IsDelim = isDelimiter(Stack[P-1]);
-  } while (P > 0 && IsDelim);
-  assert(!IsDelim);
-  return P;
-}
-
-// Register information.
-
-RegisterSet DataFlowGraph::getLandingPadLiveIns() const {
-  RegisterSet LR;
-  const Function &F = *MF.getFunction();
-  const Constant *PF = F.hasPersonalityFn() ? F.getPersonalityFn()
-                                            : nullptr;
-  const TargetLowering &TLI = *MF.getSubtarget().getTargetLowering();
-  if (RegisterId R = TLI.getExceptionPointerRegister(PF))
-    LR.insert(RegisterRef(R));
-  if (RegisterId R = TLI.getExceptionSelectorRegister(PF))
-    LR.insert(RegisterRef(R));
-  return LR;
-}
-
-// Node management functions.
-
-// Get the pointer to the node with the id N.
-NodeBase *DataFlowGraph::ptr(NodeId N) const {
-  if (N == 0)
-    return nullptr;
-  return Memory.ptr(N);
-}
-
-// Get the id of the node at the address P.
-NodeId DataFlowGraph::id(const NodeBase *P) const {
-  if (P == nullptr)
-    return 0;
-  return Memory.id(P);
-}
-
-// Allocate a new node and set the attributes to Attrs.
-NodeAddr<NodeBase*> DataFlowGraph::newNode(uint16_t Attrs) {
-  NodeAddr<NodeBase*> P = Memory.New();
-  P.Addr->init();
-  P.Addr->setAttrs(Attrs);
-  return P;
-}
-
-// Make a copy of the given node B, except for the data-flow links, which
-// are set to 0.
-NodeAddr<NodeBase*> DataFlowGraph::cloneNode(const NodeAddr<NodeBase*> B) {
-  NodeAddr<NodeBase*> NA = newNode(0);
-  memcpy(NA.Addr, B.Addr, sizeof(NodeBase));
-  // Ref nodes need to have the data-flow links reset.
-  if (NA.Addr->getType() == NodeAttrs::Ref) {
-    NodeAddr<RefNode*> RA = NA;
-    RA.Addr->setReachingDef(0);
-    RA.Addr->setSibling(0);
-    if (NA.Addr->getKind() == NodeAttrs::Def) {
-      NodeAddr<DefNode*> DA = NA;
-      DA.Addr->setReachedDef(0);
-      DA.Addr->setReachedUse(0);
-    }
-  }
-  return NA;
-}
-
-// Allocation routines for specific node types/kinds.
-
-NodeAddr<UseNode*> DataFlowGraph::newUse(NodeAddr<InstrNode*> Owner,
-      MachineOperand &Op, uint16_t Flags) {
-  NodeAddr<UseNode*> UA = newNode(NodeAttrs::Ref | NodeAttrs::Use | Flags);
-  UA.Addr->setRegRef(&Op, *this);
-  return UA;
-}
-
-NodeAddr<PhiUseNode*> DataFlowGraph::newPhiUse(NodeAddr<PhiNode*> Owner,
-      RegisterRef RR, NodeAddr<BlockNode*> PredB, uint16_t Flags) {
-  NodeAddr<PhiUseNode*> PUA = newNode(NodeAttrs::Ref | NodeAttrs::Use | Flags);
-  assert(Flags & NodeAttrs::PhiRef);
-  PUA.Addr->setRegRef(RR, *this);
-  PUA.Addr->setPredecessor(PredB.Id);
-  return PUA;
-}
-
-NodeAddr<DefNode*> DataFlowGraph::newDef(NodeAddr<InstrNode*> Owner,
-      MachineOperand &Op, uint16_t Flags) {
-  NodeAddr<DefNode*> DA = newNode(NodeAttrs::Ref | NodeAttrs::Def | Flags);
-  DA.Addr->setRegRef(&Op, *this);
-  return DA;
-}
-
-NodeAddr<DefNode*> DataFlowGraph::newDef(NodeAddr<InstrNode*> Owner,
-      RegisterRef RR, uint16_t Flags) {
-  NodeAddr<DefNode*> DA = newNode(NodeAttrs::Ref | NodeAttrs::Def | Flags);
-  assert(Flags & NodeAttrs::PhiRef);
-  DA.Addr->setRegRef(RR, *this);
-  return DA;
-}
-
-NodeAddr<PhiNode*> DataFlowGraph::newPhi(NodeAddr<BlockNode*> Owner) {
-  NodeAddr<PhiNode*> PA = newNode(NodeAttrs::Code | NodeAttrs::Phi);
-  Owner.Addr->addPhi(PA, *this);
-  return PA;
-}
-
-NodeAddr<StmtNode*> DataFlowGraph::newStmt(NodeAddr<BlockNode*> Owner,
-      MachineInstr *MI) {
-  NodeAddr<StmtNode*> SA = newNode(NodeAttrs::Code | NodeAttrs::Stmt);
-  SA.Addr->setCode(MI);
-  Owner.Addr->addMember(SA, *this);
-  return SA;
-}
-
-NodeAddr<BlockNode*> DataFlowGraph::newBlock(NodeAddr<FuncNode*> Owner,
-      MachineBasicBlock *BB) {
-  NodeAddr<BlockNode*> BA = newNode(NodeAttrs::Code | NodeAttrs::Block);
-  BA.Addr->setCode(BB);
-  Owner.Addr->addMember(BA, *this);
-  return BA;
-}
-
-NodeAddr<FuncNode*> DataFlowGraph::newFunc(MachineFunction *MF) {
-  NodeAddr<FuncNode*> FA = newNode(NodeAttrs::Code | NodeAttrs::Func);
-  FA.Addr->setCode(MF);
-  return FA;
-}
-
-// Build the data flow graph.
-void DataFlowGraph::build(unsigned Options) {
-  reset();
-  Func = newFunc(&MF);
-
-  if (MF.empty())
-    return;
-
-  for (MachineBasicBlock &B : MF) {
-    NodeAddr<BlockNode*> BA = newBlock(Func, &B);
-    BlockNodes.insert(std::make_pair(&B, BA));
-    for (MachineInstr &I : B) {
-      if (I.isDebugValue())
-        continue;
-      buildStmt(BA, I);
-    }
-  }
-
-  NodeAddr<BlockNode*> EA = Func.Addr->getEntryBlock(*this);
-  NodeList Blocks = Func.Addr->members(*this);
-
-  // Collect information about block references.
-  BlockRefsMap RefM;
-  buildBlockRefs(EA, RefM);
-
-  // Collect function live-ins and entry block live-ins.
-  MachineRegisterInfo &MRI = MF.getRegInfo();
-  MachineBasicBlock &EntryB = *EA.Addr->getCode();
-  assert(EntryB.pred_empty() && "Function entry block has predecessors");
-  for (auto I = MRI.livein_begin(), E = MRI.livein_end(); I != E; ++I)
-    LiveIns.insert(RegisterRef(I->first));
-  if (MRI.tracksLiveness()) {
-    for (auto I : EntryB.liveins())
-      LiveIns.insert(RegisterRef(I.PhysReg, I.LaneMask));
-  }
-
-  // Add function-entry phi nodes for the live-in registers.
-  //for (std::pair<RegisterId,LaneBitmask> P : LiveIns) {
-  for (auto I = LiveIns.rr_begin(), E = LiveIns.rr_end(); I != E; ++I) {
-    RegisterRef RR = *I;
-    NodeAddr<PhiNode*> PA = newPhi(EA);
-    uint16_t PhiFlags = NodeAttrs::PhiRef | NodeAttrs::Preserving;
-    NodeAddr<DefNode*> DA = newDef(PA, RR, PhiFlags);
-    PA.Addr->addMember(DA, *this);
-  }
-
-  // Add phis for landing pads.
-  // Landing pads, unlike usual backs blocks, are not entered through
-  // branches in the program, or fall-throughs from other blocks. They
-  // are entered from the exception handling runtime and target's ABI
-  // may define certain registers as defined on entry to such a block.
-  RegisterSet EHRegs = getLandingPadLiveIns();
-  if (!EHRegs.empty()) {
-    for (NodeAddr<BlockNode*> BA : Blocks) {
-      const MachineBasicBlock &B = *BA.Addr->getCode();
-      if (!B.isEHPad())
-        continue;
-
-      // Prepare a list of NodeIds of the block's predecessors.
-      NodeList Preds;
-      for (MachineBasicBlock *PB : B.predecessors())
-        Preds.push_back(findBlock(PB));
-
-      // Build phi nodes for each live-in.
-      for (RegisterRef RR : EHRegs) {
-        NodeAddr<PhiNode*> PA = newPhi(BA);
-        uint16_t PhiFlags = NodeAttrs::PhiRef | NodeAttrs::Preserving;
-        // Add def:
-        NodeAddr<DefNode*> DA = newDef(PA, RR, PhiFlags);
-        PA.Addr->addMember(DA, *this);
-        // Add uses (no reaching defs for phi uses):
-        for (NodeAddr<BlockNode*> PBA : Preds) {
-          NodeAddr<PhiUseNode*> PUA = newPhiUse(PA, RR, PBA);
-          PA.Addr->addMember(PUA, *this);
-        }
-      }
-    }
-  }
-
-  // Build a map "PhiM" which will contain, for each block, the set
-  // of references that will require phi definitions in that block.
-  BlockRefsMap PhiM;
-  for (NodeAddr<BlockNode*> BA : Blocks)
-    recordDefsForDF(PhiM, RefM, BA);
-  for (NodeAddr<BlockNode*> BA : Blocks)
-    buildPhis(PhiM, RefM, BA);
-
-  // Link all the refs. This will recursively traverse the dominator tree.
-  DefStackMap DM;
-  linkBlockRefs(DM, EA);
-
-  // Finally, remove all unused phi nodes.
-  if (!(Options & BuildOptions::KeepDeadPhis))
-    removeUnusedPhis();
-}
-
-RegisterRef DataFlowGraph::makeRegRef(unsigned Reg, unsigned Sub) const {
-  assert(PhysicalRegisterInfo::isRegMaskId(Reg) ||
-         TargetRegisterInfo::isPhysicalRegister(Reg));
-  assert(Reg != 0);
-  if (Sub != 0)
-    Reg = TRI.getSubReg(Reg, Sub);
-  return RegisterRef(Reg);
-}
-
-RegisterRef DataFlowGraph::makeRegRef(const MachineOperand &Op) const {
-  assert(Op.isReg() || Op.isRegMask());
-  if (Op.isReg())
-    return makeRegRef(Op.getReg(), Op.getSubReg());
-  return RegisterRef(PRI.getRegMaskId(Op.getRegMask()), LaneBitmask::getAll());
-}
-
-RegisterRef DataFlowGraph::restrictRef(RegisterRef AR, RegisterRef BR) const {
-  if (AR.Reg == BR.Reg) {
-    LaneBitmask M = AR.Mask & BR.Mask;
-    return M.any() ? RegisterRef(AR.Reg, M) : RegisterRef();
-  }
-#ifndef NDEBUG
-//  RegisterRef NAR = PRI.normalize(AR);
-//  RegisterRef NBR = PRI.normalize(BR);
-//  assert(NAR.Reg != NBR.Reg);
-#endif
-  // This isn't strictly correct, because the overlap may happen in the
-  // part masked out.
-  if (PRI.alias(AR, BR))
-    return AR;
-  return RegisterRef();
-}
-
-// For each stack in the map DefM, push the delimiter for block B on it.
-void DataFlowGraph::markBlock(NodeId B, DefStackMap &DefM) {
-  // Push block delimiters.
-  for (auto I = DefM.begin(), E = DefM.end(); I != E; ++I)
-    I->second.start_block(B);
-}
-
-// Remove all definitions coming from block B from each stack in DefM.
-void DataFlowGraph::releaseBlock(NodeId B, DefStackMap &DefM) {
-  // Pop all defs from this block from the definition stack. Defs that were
-  // added to the map during the traversal of instructions will not have a
-  // delimiter, but for those, the whole stack will be emptied.
-  for (auto I = DefM.begin(), E = DefM.end(); I != E; ++I)
-    I->second.clear_block(B);
-
-  // Finally, remove empty stacks from the map.
-  for (auto I = DefM.begin(), E = DefM.end(), NextI = I; I != E; I = NextI) {
-    NextI = std::next(I);
-    // This preserves the validity of iterators other than I.
-    if (I->second.empty())
-      DefM.erase(I);
-  }
-}
-
-// Push all definitions from the instruction node IA to an appropriate
-// stack in DefM.
-void DataFlowGraph::pushAllDefs(NodeAddr<InstrNode*> IA, DefStackMap &DefM) {
-  pushClobbers(IA, DefM);
-  pushDefs(IA, DefM);
-}
-
-// Push all definitions from the instruction node IA to an appropriate
-// stack in DefM.
-void DataFlowGraph::pushClobbers(NodeAddr<InstrNode*> IA, DefStackMap &DefM) {
-  NodeSet Visited;
-  std::set<RegisterId> Defined;
-
-  // The important objectives of this function are:
-  // - to be able to handle instructions both while the graph is being
-  //   constructed, and after the graph has been constructed, and
-  // - maintain proper ordering of definitions on the stack for each
-  //   register reference:
-  //   - if there are two or more related defs in IA (i.e. coming from
-  //     the same machine operand), then only push one def on the stack,
-  //   - if there are multiple unrelated defs of non-overlapping
-  //     subregisters of S, then the stack for S will have both (in an
-  //     unspecified order), but the order does not matter from the data-
-  //     -flow perspective.
-
-  for (NodeAddr<DefNode*> DA : IA.Addr->members_if(IsDef, *this)) {
-    if (Visited.count(DA.Id))
-      continue;
-    if (!(DA.Addr->getFlags() & NodeAttrs::Clobbering))
-      continue;
-
-    NodeList Rel = getRelatedRefs(IA, DA);
-    NodeAddr<DefNode*> PDA = Rel.front();
-    RegisterRef RR = PDA.Addr->getRegRef(*this);
-
-    // Push the definition on the stack for the register and all aliases.
-    // The def stack traversal in linkNodeUp will check the exact aliasing.
-    DefM[RR.Reg].push(DA);
-    Defined.insert(RR.Reg);
-    for (RegisterId A : PRI.getAliasSet(RR.Reg)) {
-      // Check that we don't push the same def twice.
-      assert(A != RR.Reg);
-      if (!Defined.count(A))
-        DefM[A].push(DA);
-    }
-    // Mark all the related defs as visited.
-    for (NodeAddr<NodeBase*> T : Rel)
-      Visited.insert(T.Id);
-  }
-}
-
-// Push all definitions from the instruction node IA to an appropriate
-// stack in DefM.
-void DataFlowGraph::pushDefs(NodeAddr<InstrNode*> IA, DefStackMap &DefM) {
-  NodeSet Visited;
-#ifndef NDEBUG
-  std::set<RegisterId> Defined;
-#endif
-
-  // The important objectives of this function are:
-  // - to be able to handle instructions both while the graph is being
-  //   constructed, and after the graph has been constructed, and
-  // - maintain proper ordering of definitions on the stack for each
-  //   register reference:
-  //   - if there are two or more related defs in IA (i.e. coming from
-  //     the same machine operand), then only push one def on the stack,
-  //   - if there are multiple unrelated defs of non-overlapping
-  //     subregisters of S, then the stack for S will have both (in an
-  //     unspecified order), but the order does not matter from the data-
-  //     -flow perspective.
-
-  for (NodeAddr<DefNode*> DA : IA.Addr->members_if(IsDef, *this)) {
-    if (Visited.count(DA.Id))
-      continue;
-    if (DA.Addr->getFlags() & NodeAttrs::Clobbering)
-      continue;
-
-    NodeList Rel = getRelatedRefs(IA, DA);
-    NodeAddr<DefNode*> PDA = Rel.front();
-    RegisterRef RR = PDA.Addr->getRegRef(*this);
-#ifndef NDEBUG
-    // Assert if the register is defined in two or more unrelated defs.
-    // This could happen if there are two or more def operands defining it.
-    if (!Defined.insert(RR.Reg).second) {
-      MachineInstr *MI = NodeAddr<StmtNode*>(IA).Addr->getCode();
-      dbgs() << "Multiple definitions of register: "
-             << Print<RegisterRef>(RR, *this) << " in\n  " << *MI
-             << "in BB#" << MI->getParent()->getNumber() << '\n';
-      llvm_unreachable(nullptr);
-    }
-#endif
-    // Push the definition on the stack for the register and all aliases.
-    // The def stack traversal in linkNodeUp will check the exact aliasing.
-    DefM[RR.Reg].push(DA);
-    for (RegisterId A : PRI.getAliasSet(RR.Reg)) {
-      // Check that we don't push the same def twice.
-      assert(A != RR.Reg);
-      DefM[A].push(DA);
-    }
-    // Mark all the related defs as visited.
-    for (NodeAddr<NodeBase*> T : Rel)
-      Visited.insert(T.Id);
-  }
-}
-
-// Return the list of all reference nodes related to RA, including RA itself.
-// See "getNextRelated" for the meaning of a "related reference".
-NodeList DataFlowGraph::getRelatedRefs(NodeAddr<InstrNode*> IA,
-      NodeAddr<RefNode*> RA) const {
-  assert(IA.Id != 0 && RA.Id != 0);
-
-  NodeList Refs;
-  NodeId Start = RA.Id;
-  do {
-    Refs.push_back(RA);
-    RA = getNextRelated(IA, RA);
-  } while (RA.Id != 0 && RA.Id != Start);
-  return Refs;
-}
-
-// Clear all information in the graph.
-void DataFlowGraph::reset() {
-  Memory.clear();
-  BlockNodes.clear();
-  Func = NodeAddr<FuncNode*>();
-}
-
-// Return the next reference node in the instruction node IA that is related
-// to RA. Conceptually, two reference nodes are related if they refer to the
-// same instance of a register access, but differ in flags or other minor
-// characteristics. Specific examples of related nodes are shadow reference
-// nodes.
-// Return the equivalent of nullptr if there are no more related references.
-NodeAddr<RefNode*> DataFlowGraph::getNextRelated(NodeAddr<InstrNode*> IA,
-      NodeAddr<RefNode*> RA) const {
-  assert(IA.Id != 0 && RA.Id != 0);
-
-  auto Related = [this,RA](NodeAddr<RefNode*> TA) -> bool {
-    if (TA.Addr->getKind() != RA.Addr->getKind())
-      return false;
-    if (TA.Addr->getRegRef(*this) != RA.Addr->getRegRef(*this))
-      return false;
-    return true;
-  };
-  auto RelatedStmt = [&Related,RA](NodeAddr<RefNode*> TA) -> bool {
-    return Related(TA) &&
-           &RA.Addr->getOp() == &TA.Addr->getOp();
-  };
-  auto RelatedPhi = [&Related,RA](NodeAddr<RefNode*> TA) -> bool {
-    if (!Related(TA))
-      return false;
-    if (TA.Addr->getKind() != NodeAttrs::Use)
-      return true;
-    // For phi uses, compare predecessor blocks.
-    const NodeAddr<const PhiUseNode*> TUA = TA;
-    const NodeAddr<const PhiUseNode*> RUA = RA;
-    return TUA.Addr->getPredecessor() == RUA.Addr->getPredecessor();
-  };
-
-  RegisterRef RR = RA.Addr->getRegRef(*this);
-  if (IA.Addr->getKind() == NodeAttrs::Stmt)
-    return RA.Addr->getNextRef(RR, RelatedStmt, true, *this);
-  return RA.Addr->getNextRef(RR, RelatedPhi, true, *this);
-}
-
-// Find the next node related to RA in IA that satisfies condition P.
-// If such a node was found, return a pair where the second element is the
-// located node. If such a node does not exist, return a pair where the
-// first element is the element after which such a node should be inserted,
-// and the second element is a null-address.
-template <typename Predicate>
-std::pair<NodeAddr<RefNode*>,NodeAddr<RefNode*>>
-DataFlowGraph::locateNextRef(NodeAddr<InstrNode*> IA, NodeAddr<RefNode*> RA,
-      Predicate P) const {
-  assert(IA.Id != 0 && RA.Id != 0);
-
-  NodeAddr<RefNode*> NA;
-  NodeId Start = RA.Id;
-  while (true) {
-    NA = getNextRelated(IA, RA);
-    if (NA.Id == 0 || NA.Id == Start)
-      break;
-    if (P(NA))
-      break;
-    RA = NA;
-  }
-
-  if (NA.Id != 0 && NA.Id != Start)
-    return std::make_pair(RA, NA);
-  return std::make_pair(RA, NodeAddr<RefNode*>());
-}
-
-// Get the next shadow node in IA corresponding to RA, and optionally create
-// such a node if it does not exist.
-NodeAddr<RefNode*> DataFlowGraph::getNextShadow(NodeAddr<InstrNode*> IA,
-      NodeAddr<RefNode*> RA, bool Create) {
-  assert(IA.Id != 0 && RA.Id != 0);
-
-  uint16_t Flags = RA.Addr->getFlags() | NodeAttrs::Shadow;
-  auto IsShadow = [Flags] (NodeAddr<RefNode*> TA) -> bool {
-    return TA.Addr->getFlags() == Flags;
-  };
-  auto Loc = locateNextRef(IA, RA, IsShadow);
-  if (Loc.second.Id != 0 || !Create)
-    return Loc.second;
-
-  // Create a copy of RA and mark is as shadow.
-  NodeAddr<RefNode*> NA = cloneNode(RA);
-  NA.Addr->setFlags(Flags | NodeAttrs::Shadow);
-  IA.Addr->addMemberAfter(Loc.first, NA, *this);
-  return NA;
-}
-
-// Get the next shadow node in IA corresponding to RA. Return null-address
-// if such a node does not exist.
-NodeAddr<RefNode*> DataFlowGraph::getNextShadow(NodeAddr<InstrNode*> IA,
-      NodeAddr<RefNode*> RA) const {
-  assert(IA.Id != 0 && RA.Id != 0);
-  uint16_t Flags = RA.Addr->getFlags() | NodeAttrs::Shadow;
-  auto IsShadow = [Flags] (NodeAddr<RefNode*> TA) -> bool {
-    return TA.Addr->getFlags() == Flags;
-  };
-  return locateNextRef(IA, RA, IsShadow).second;
-}
-
-// Create a new statement node in the block node BA that corresponds to
-// the machine instruction MI.
-void DataFlowGraph::buildStmt(NodeAddr<BlockNode*> BA, MachineInstr &In) {
-  NodeAddr<StmtNode*> SA = newStmt(BA, &In);
-
-  auto isCall = [] (const MachineInstr &In) -> bool {
-    if (In.isCall())
-      return true;
-    // Is tail call?
-    if (In.isBranch()) {
-      for (const MachineOperand &Op : In.operands())
-        if (Op.isGlobal() || Op.isSymbol())
-          return true;
-      // Assume indirect branches are calls. This is for the purpose of
-      // keeping implicit operands, and so it won't hurt on intra-function
-      // indirect branches.
-      if (In.isIndirectBranch())
-        return true;
-    }
-    return false;
-  };
-
-  auto isDefUndef = [this] (const MachineInstr &In, RegisterRef DR) -> bool {
-    // This instruction defines DR. Check if there is a use operand that
-    // would make DR live on entry to the instruction.
-    for (const MachineOperand &Op : In.operands()) {
-      if (!Op.isReg() || Op.getReg() == 0 || !Op.isUse() || Op.isUndef())
-        continue;
-      RegisterRef UR = makeRegRef(Op);
-      if (PRI.alias(DR, UR))
-        return false;
-    }
-    return true;
-  };
-
-  bool IsCall = isCall(In);
-  unsigned NumOps = In.getNumOperands();
-
-  // Avoid duplicate implicit defs. This will not detect cases of implicit
-  // defs that define registers that overlap, but it is not clear how to
-  // interpret that in the absence of explicit defs. Overlapping explicit
-  // defs are likely illegal already.
-  BitVector DoneDefs(TRI.getNumRegs());
-  // Process explicit defs first.
-  for (unsigned OpN = 0; OpN < NumOps; ++OpN) {
-    MachineOperand &Op = In.getOperand(OpN);
-    if (!Op.isReg() || !Op.isDef() || Op.isImplicit())
-      continue;
-    unsigned R = Op.getReg();
-    if (!R || !TargetRegisterInfo::isPhysicalRegister(R))
-      continue;
-    uint16_t Flags = NodeAttrs::None;
-    if (TOI.isPreserving(In, OpN)) {
-      Flags |= NodeAttrs::Preserving;
-      // If the def is preserving, check if it is also undefined.
-      if (isDefUndef(In, makeRegRef(Op)))
-        Flags |= NodeAttrs::Undef;
-    }
-    if (TOI.isClobbering(In, OpN))
-      Flags |= NodeAttrs::Clobbering;
-    if (TOI.isFixedReg(In, OpN))
-      Flags |= NodeAttrs::Fixed;
-    if (IsCall && Op.isDead())
-      Flags |= NodeAttrs::Dead;
-    NodeAddr<DefNode*> DA = newDef(SA, Op, Flags);
-    SA.Addr->addMember(DA, *this);
-    assert(!DoneDefs.test(R));
-    DoneDefs.set(R);
-  }
-
-  // Process reg-masks (as clobbers).
-  BitVector DoneClobbers(TRI.getNumRegs());
-  for (unsigned OpN = 0; OpN < NumOps; ++OpN) {
-    MachineOperand &Op = In.getOperand(OpN);
-    if (!Op.isRegMask())
-      continue;
-    uint16_t Flags = NodeAttrs::Clobbering | NodeAttrs::Fixed |
-                     NodeAttrs::Dead;
-    NodeAddr<DefNode*> DA = newDef(SA, Op, Flags);
-    SA.Addr->addMember(DA, *this);
-    // Record all clobbered registers in DoneDefs.
-    const uint32_t *RM = Op.getRegMask();
-    for (unsigned i = 1, e = TRI.getNumRegs(); i != e; ++i)
-      if (!(RM[i/32] & (1u << (i%32))))
-        DoneClobbers.set(i);
-  }
-
-  // Process implicit defs, skipping those that have already been added
-  // as explicit.
-  for (unsigned OpN = 0; OpN < NumOps; ++OpN) {
-    MachineOperand &Op = In.getOperand(OpN);
-    if (!Op.isReg() || !Op.isDef() || !Op.isImplicit())
-      continue;
-    unsigned R = Op.getReg();
-    if (!R || !TargetRegisterInfo::isPhysicalRegister(R) || DoneDefs.test(R))
-      continue;
-    RegisterRef RR = makeRegRef(Op);
-    uint16_t Flags = NodeAttrs::None;
-    if (TOI.isPreserving(In, OpN)) {
-      Flags |= NodeAttrs::Preserving;
-      // If the def is preserving, check if it is also undefined.
-      if (isDefUndef(In, RR))
-        Flags |= NodeAttrs::Undef;
-    }
-    if (TOI.isClobbering(In, OpN))
-      Flags |= NodeAttrs::Clobbering;
-    if (TOI.isFixedReg(In, OpN))
-      Flags |= NodeAttrs::Fixed;
-    if (IsCall && Op.isDead()) {
-      if (DoneClobbers.test(R))
-        continue;
-      Flags |= NodeAttrs::Dead;
-    }
-    NodeAddr<DefNode*> DA = newDef(SA, Op, Flags);
-    SA.Addr->addMember(DA, *this);
-    DoneDefs.set(R);
-  }
-
-  for (unsigned OpN = 0; OpN < NumOps; ++OpN) {
-    MachineOperand &Op = In.getOperand(OpN);
-    if (!Op.isReg() || !Op.isUse())
-      continue;
-    unsigned R = Op.getReg();
-    if (!R || !TargetRegisterInfo::isPhysicalRegister(R))
-      continue;
-    uint16_t Flags = NodeAttrs::None;
-    if (Op.isUndef())
-      Flags |= NodeAttrs::Undef;
-    if (TOI.isFixedReg(In, OpN))
-      Flags |= NodeAttrs::Fixed;
-    NodeAddr<UseNode*> UA = newUse(SA, Op, Flags);
-    SA.Addr->addMember(UA, *this);
-  }
-}
-
-// Build a map that for each block will have the set of all references from
-// that block, and from all blocks dominated by it.
-void DataFlowGraph::buildBlockRefs(NodeAddr<BlockNode*> BA,
-      BlockRefsMap &RefM) {
-  RegisterSet &Refs = RefM[BA.Id];
-  MachineDomTreeNode *N = MDT.getNode(BA.Addr->getCode());
-  assert(N);
-  for (auto I : *N) {
-    MachineBasicBlock *SB = I->getBlock();
-    NodeAddr<BlockNode*> SBA = findBlock(SB);
-    buildBlockRefs(SBA, RefM);
-    const RegisterSet &RefsS = RefM[SBA.Id];
-    Refs.insert(RefsS.begin(), RefsS.end());
-  }
-
-  for (NodeAddr<InstrNode*> IA : BA.Addr->members(*this))
-    for (NodeAddr<RefNode*> RA : IA.Addr->members(*this))
-      Refs.insert(RA.Addr->getRegRef(*this));
-}
-
-// Scan all defs in the block node BA and record in PhiM the locations of
-// phi nodes corresponding to these defs.
-void DataFlowGraph::recordDefsForDF(BlockRefsMap &PhiM, BlockRefsMap &RefM,
-      NodeAddr<BlockNode*> BA) {
-  // Check all defs from block BA and record them in each block in BA's
-  // iterated dominance frontier. This information will later be used to
-  // create phi nodes.
-  MachineBasicBlock *BB = BA.Addr->getCode();
-  assert(BB);
-  auto DFLoc = MDF.find(BB);
-  if (DFLoc == MDF.end() || DFLoc->second.empty())
-    return;
-
-  // Traverse all instructions in the block and collect the set of all
-  // defined references. For each reference there will be a phi created
-  // in the block's iterated dominance frontier.
-  // This is done to make sure that each defined reference gets only one
-  // phi node, even if it is defined multiple times.
-  RegisterSet Defs;
-  for (NodeAddr<InstrNode*> IA : BA.Addr->members(*this))
-    for (NodeAddr<RefNode*> RA : IA.Addr->members_if(IsDef, *this))
-      Defs.insert(RA.Addr->getRegRef(*this));
-
-  // Calculate the iterated dominance frontier of BB.
-  const MachineDominanceFrontier::DomSetType &DF = DFLoc->second;
-  SetVector<MachineBasicBlock*> IDF(DF.begin(), DF.end());
-  for (unsigned i = 0; i < IDF.size(); ++i) {
-    auto F = MDF.find(IDF[i]);
-    if (F != MDF.end())
-      IDF.insert(F->second.begin(), F->second.end());
-  }
-
-  // Get the register references that are reachable from this block.
-  RegisterSet &Refs = RefM[BA.Id];
-  for (auto DB : IDF) {
-    NodeAddr<BlockNode*> DBA = findBlock(DB);
-    const RegisterSet &RefsD = RefM[DBA.Id];
-    Refs.insert(RefsD.begin(), RefsD.end());
-  }
-
-  // Finally, add the set of defs to each block in the iterated dominance
-  // frontier.
-  for (auto DB : IDF) {
-    NodeAddr<BlockNode*> DBA = findBlock(DB);
-    PhiM[DBA.Id].insert(Defs.begin(), Defs.end());
-  }
-}
-
-// Given the locations of phi nodes in the map PhiM, create the phi nodes
-// that are located in the block node BA.
-void DataFlowGraph::buildPhis(BlockRefsMap &PhiM, BlockRefsMap &RefM,
-      NodeAddr<BlockNode*> BA) {
-  // Check if this blocks has any DF defs, i.e. if there are any defs
-  // that this block is in the iterated dominance frontier of.
-  auto HasDF = PhiM.find(BA.Id);
-  if (HasDF == PhiM.end() || HasDF->second.empty())
-    return;
-
-  // First, remove all R in Refs in such that there exists T in Refs
-  // such that T covers R. In other words, only leave those refs that
-  // are not covered by another ref (i.e. maximal with respect to covering).
-
-  auto MaxCoverIn = [this] (RegisterRef RR, RegisterSet &RRs) -> RegisterRef {
-    for (RegisterRef I : RRs)
-      if (I != RR && RegisterAggr::isCoverOf(I, RR, PRI))
-        RR = I;
-    return RR;
-  };
-
-  RegisterSet MaxDF;
-  for (RegisterRef I : HasDF->second)
-    MaxDF.insert(MaxCoverIn(I, HasDF->second));
-
-  std::vector<RegisterRef> MaxRefs;
-  RegisterSet &RefB = RefM[BA.Id];
-  for (RegisterRef I : MaxDF)
-    MaxRefs.push_back(MaxCoverIn(I, RefB));
-
-  // Now, for each R in MaxRefs, get the alias closure of R. If the closure
-  // only has R in it, create a phi a def for R. Otherwise, create a phi,
-  // and add a def for each S in the closure.
-
-  // Sort the refs so that the phis will be created in a deterministic order.
-  std::sort(MaxRefs.begin(), MaxRefs.end());
-  // Remove duplicates.
-  auto NewEnd = std::unique(MaxRefs.begin(), MaxRefs.end());
-  MaxRefs.erase(NewEnd, MaxRefs.end());
-
-  auto Aliased = [this,&MaxRefs](RegisterRef RR,
-                                 std::vector<unsigned> &Closure) -> bool {
-    for (unsigned I : Closure)
-      if (PRI.alias(RR, MaxRefs[I]))
-        return true;
-    return false;
-  };
-
-  // Prepare a list of NodeIds of the block's predecessors.
-  NodeList Preds;
-  const MachineBasicBlock *MBB = BA.Addr->getCode();
-  for (MachineBasicBlock *PB : MBB->predecessors())
-    Preds.push_back(findBlock(PB));
-
-  while (!MaxRefs.empty()) {
-    // Put the first element in the closure, and then add all subsequent
-    // elements from MaxRefs to it, if they alias at least one element
-    // already in the closure.
-    // ClosureIdx: vector of indices in MaxRefs of members of the closure.
-    std::vector<unsigned> ClosureIdx = { 0 };
-    for (unsigned i = 1; i != MaxRefs.size(); ++i)
-      if (Aliased(MaxRefs[i], ClosureIdx))
-        ClosureIdx.push_back(i);
-
-    // Build a phi for the closure.
-    unsigned CS = ClosureIdx.size();
-    NodeAddr<PhiNode*> PA = newPhi(BA);
-
-    // Add defs.
-    for (unsigned X = 0; X != CS; ++X) {
-      RegisterRef RR = MaxRefs[ClosureIdx[X]];
-      uint16_t PhiFlags = NodeAttrs::PhiRef | NodeAttrs::Preserving;
-      NodeAddr<DefNode*> DA = newDef(PA, RR, PhiFlags);
-      PA.Addr->addMember(DA, *this);
-    }
-    // Add phi uses.
-    for (NodeAddr<BlockNode*> PBA : Preds) {
-      for (unsigned X = 0; X != CS; ++X) {
-        RegisterRef RR = MaxRefs[ClosureIdx[X]];
-        NodeAddr<PhiUseNode*> PUA = newPhiUse(PA, RR, PBA);
-        PA.Addr->addMember(PUA, *this);
-      }
-    }
-
-    // Erase from MaxRefs all elements in the closure.
-    auto Begin = MaxRefs.begin();
-    for (unsigned i = ClosureIdx.size(); i != 0; --i)
-      MaxRefs.erase(Begin + ClosureIdx[i-1]);
-  }
-}
-
-// Remove any unneeded phi nodes that were created during the build process.
-void DataFlowGraph::removeUnusedPhis() {
-  // This will remove unused phis, i.e. phis where each def does not reach
-  // any uses or other defs. This will not detect or remove circular phi
-  // chains that are otherwise dead. Unused/dead phis are created during
-  // the build process and this function is intended to remove these cases
-  // that are easily determinable to be unnecessary.
-
-  SetVector<NodeId> PhiQ;
-  for (NodeAddr<BlockNode*> BA : Func.Addr->members(*this)) {
-    for (auto P : BA.Addr->members_if(IsPhi, *this))
-      PhiQ.insert(P.Id);
-  }
-
-  static auto HasUsedDef = [](NodeList &Ms) -> bool {
-    for (NodeAddr<NodeBase*> M : Ms) {
-      if (M.Addr->getKind() != NodeAttrs::Def)
-        continue;
-      NodeAddr<DefNode*> DA = M;
-      if (DA.Addr->getReachedDef() != 0 || DA.Addr->getReachedUse() != 0)
-        return true;
-    }
-    return false;
-  };
-
-  // Any phi, if it is removed, may affect other phis (make them dead).
-  // For each removed phi, collect the potentially affected phis and add
-  // them back to the queue.
-  while (!PhiQ.empty()) {
-    auto PA = addr<PhiNode*>(PhiQ[0]);
-    PhiQ.remove(PA.Id);
-    NodeList Refs = PA.Addr->members(*this);
-    if (HasUsedDef(Refs))
-      continue;
-    for (NodeAddr<RefNode*> RA : Refs) {
-      if (NodeId RD = RA.Addr->getReachingDef()) {
-        auto RDA = addr<DefNode*>(RD);
-        NodeAddr<InstrNode*> OA = RDA.Addr->getOwner(*this);
-        if (IsPhi(OA))
-          PhiQ.insert(OA.Id);
-      }
-      if (RA.Addr->isDef())
-        unlinkDef(RA, true);
-      else
-        unlinkUse(RA, true);
-    }
-    NodeAddr<BlockNode*> BA = PA.Addr->getOwner(*this);
-    BA.Addr->removeMember(PA, *this);
-  }
-}
-
-// For a given reference node TA in an instruction node IA, connect the
-// reaching def of TA to the appropriate def node. Create any shadow nodes
-// as appropriate.
-template <typename T>
-void DataFlowGraph::linkRefUp(NodeAddr<InstrNode*> IA, NodeAddr<T> TA,
-      DefStack &DS) {
-  if (DS.empty())
-    return;
-  RegisterRef RR = TA.Addr->getRegRef(*this);
-  NodeAddr<T> TAP;
-
-  // References from the def stack that have been examined so far.
-  RegisterAggr Defs(PRI);
-
-  for (auto I = DS.top(), E = DS.bottom(); I != E; I.down()) {
-    RegisterRef QR = I->Addr->getRegRef(*this);
-
-    // Skip all defs that are aliased to any of the defs that we have already
-    // seen. If this completes a cover of RR, stop the stack traversal.
-    bool Alias = Defs.hasAliasOf(QR);
-    bool Cover = Defs.insert(QR).hasCoverOf(RR);
-    if (Alias) {
-      if (Cover)
-        break;
-      continue;
-    }
-
-    // The reaching def.
-    NodeAddr<DefNode*> RDA = *I;
-
-    // Pick the reached node.
-    if (TAP.Id == 0) {
-      TAP = TA;
-    } else {
-      // Mark the existing ref as "shadow" and create a new shadow.
-      TAP.Addr->setFlags(TAP.Addr->getFlags() | NodeAttrs::Shadow);
-      TAP = getNextShadow(IA, TAP, true);
-    }
-
-    // Create the link.
-    TAP.Addr->linkToDef(TAP.Id, RDA);
-
-    if (Cover)
-      break;
-  }
-}
-
-// Create data-flow links for all reference nodes in the statement node SA.
-template <typename Predicate>
-void DataFlowGraph::linkStmtRefs(DefStackMap &DefM, NodeAddr<StmtNode*> SA,
-      Predicate P) {
-#ifndef NDEBUG
-  RegisterSet Defs;
-#endif
-
-  // Link all nodes (upwards in the data-flow) with their reaching defs.
-  for (NodeAddr<RefNode*> RA : SA.Addr->members_if(P, *this)) {
-    uint16_t Kind = RA.Addr->getKind();
-    assert(Kind == NodeAttrs::Def || Kind == NodeAttrs::Use);
-    RegisterRef RR = RA.Addr->getRegRef(*this);
-#ifndef NDEBUG
-    // Do not expect multiple defs of the same reference.
-    assert(Kind != NodeAttrs::Def || !Defs.count(RR));
-    Defs.insert(RR);
-#endif
-
-    auto F = DefM.find(RR.Reg);
-    if (F == DefM.end())
-      continue;
-    DefStack &DS = F->second;
-    if (Kind == NodeAttrs::Use)
-      linkRefUp<UseNode*>(SA, RA, DS);
-    else if (Kind == NodeAttrs::Def)
-      linkRefUp<DefNode*>(SA, RA, DS);
-    else
-      llvm_unreachable("Unexpected node in instruction");
-  }
-}
-
-// Create data-flow links for all instructions in the block node BA. This
-// will include updating any phi nodes in BA.
-void DataFlowGraph::linkBlockRefs(DefStackMap &DefM, NodeAddr<BlockNode*> BA) {
-  // Push block delimiters.
-  markBlock(BA.Id, DefM);
-
-  auto IsClobber = [] (NodeAddr<RefNode*> RA) -> bool {
-    return IsDef(RA) && (RA.Addr->getFlags() & NodeAttrs::Clobbering);
-  };
-  auto IsNoClobber = [] (NodeAddr<RefNode*> RA) -> bool {
-    return IsDef(RA) && !(RA.Addr->getFlags() & NodeAttrs::Clobbering);
-  };
-
-  assert(BA.Addr && "block node address is needed to create a data-flow link");
-  // For each non-phi instruction in the block, link all the defs and uses
-  // to their reaching defs. For any member of the block (including phis),
-  // push the defs on the corresponding stacks.
-  for (NodeAddr<InstrNode*> IA : BA.Addr->members(*this)) {
-    // Ignore phi nodes here. They will be linked part by part from the
-    // predecessors.
-    if (IA.Addr->getKind() == NodeAttrs::Stmt) {
-      linkStmtRefs(DefM, IA, IsUse);
-      linkStmtRefs(DefM, IA, IsClobber);
-    }
-
-    // Push the definitions on the stack.
-    pushClobbers(IA, DefM);
-
-    if (IA.Addr->getKind() == NodeAttrs::Stmt)
-      linkStmtRefs(DefM, IA, IsNoClobber);
-
-    pushDefs(IA, DefM);
-  }
-
-  // Recursively process all children in the dominator tree.
-  MachineDomTreeNode *N = MDT.getNode(BA.Addr->getCode());
-  for (auto I : *N) {
-    MachineBasicBlock *SB = I->getBlock();
-    NodeAddr<BlockNode*> SBA = findBlock(SB);
-    linkBlockRefs(DefM, SBA);
-  }
-
-  // Link the phi uses from the successor blocks.
-  auto IsUseForBA = [BA](NodeAddr<NodeBase*> NA) -> bool {
-    if (NA.Addr->getKind() != NodeAttrs::Use)
-      return false;
-    assert(NA.Addr->getFlags() & NodeAttrs::PhiRef);
-    NodeAddr<PhiUseNode*> PUA = NA;
-    return PUA.Addr->getPredecessor() == BA.Id;
-  };
-
-  RegisterSet EHLiveIns = getLandingPadLiveIns();
-  MachineBasicBlock *MBB = BA.Addr->getCode();
-
-  for (MachineBasicBlock *SB : MBB->successors()) {
-    bool IsEHPad = SB->isEHPad();
-    NodeAddr<BlockNode*> SBA = findBlock(SB);
-    for (NodeAddr<InstrNode*> IA : SBA.Addr->members_if(IsPhi, *this)) {
-      // Do not link phi uses for landing pad live-ins.
-      if (IsEHPad) {
-        // Find what register this phi is for.
-        NodeAddr<RefNode*> RA = IA.Addr->getFirstMember(*this);
-        assert(RA.Id != 0);
-        if (EHLiveIns.count(RA.Addr->getRegRef(*this)))
-          continue;
-      }
-      // Go over each phi use associated with MBB, and link it.
-      for (auto U : IA.Addr->members_if(IsUseForBA, *this)) {
-        NodeAddr<PhiUseNode*> PUA = U;
-        RegisterRef RR = PUA.Addr->getRegRef(*this);
-        linkRefUp<UseNode*>(IA, PUA, DefM[RR.Reg]);
-      }
-    }
-  }
-
-  // Pop all defs from this block from the definition stacks.
-  releaseBlock(BA.Id, DefM);
-}
-
-// Remove the use node UA from any data-flow and structural links.
-void DataFlowGraph::unlinkUseDF(NodeAddr<UseNode*> UA) {
-  NodeId RD = UA.Addr->getReachingDef();
-  NodeId Sib = UA.Addr->getSibling();
-
-  if (RD == 0) {
-    assert(Sib == 0);
-    return;
-  }
-
-  auto RDA = addr<DefNode*>(RD);
-  auto TA = addr<UseNode*>(RDA.Addr->getReachedUse());
-  if (TA.Id == UA.Id) {
-    RDA.Addr->setReachedUse(Sib);
-    return;
-  }
-
-  while (TA.Id != 0) {
-    NodeId S = TA.Addr->getSibling();
-    if (S == UA.Id) {
-      TA.Addr->setSibling(UA.Addr->getSibling());
-      return;
-    }
-    TA = addr<UseNode*>(S);
-  }
-}
-
-// Remove the def node DA from any data-flow and structural links.
-void DataFlowGraph::unlinkDefDF(NodeAddr<DefNode*> DA) {
-  //
-  //         RD
-  //         | reached
-  //         | def
-  //         :
-  //         .
-  //        +----+
-  // ... -- | DA | -- ... -- 0  : sibling chain of DA
-  //        +----+
-  //         |  | reached
-  //         |  : def
-  //         |  .
-  //         | ...  : Siblings (defs)
-  //         |
-  //         : reached
-  //         . use
-  //        ... : sibling chain of reached uses
-
-  NodeId RD = DA.Addr->getReachingDef();
-
-  // Visit all siblings of the reached def and reset their reaching defs.
-  // Also, defs reached by DA are now "promoted" to being reached by RD,
-  // so all of them will need to be spliced into the sibling chain where
-  // DA belongs.
-  auto getAllNodes = [this] (NodeId N) -> NodeList {
-    NodeList Res;
-    while (N) {
-      auto RA = addr<RefNode*>(N);
-      // Keep the nodes in the exact sibling order.
-      Res.push_back(RA);
-      N = RA.Addr->getSibling();
-    }
-    return Res;
-  };
-  NodeList ReachedDefs = getAllNodes(DA.Addr->getReachedDef());
-  NodeList ReachedUses = getAllNodes(DA.Addr->getReachedUse());
-
-  if (RD == 0) {
-    for (NodeAddr<RefNode*> I : ReachedDefs)
-      I.Addr->setSibling(0);
-    for (NodeAddr<RefNode*> I : ReachedUses)
-      I.Addr->setSibling(0);
-  }
-  for (NodeAddr<DefNode*> I : ReachedDefs)
-    I.Addr->setReachingDef(RD);
-  for (NodeAddr<UseNode*> I : ReachedUses)
-    I.Addr->setReachingDef(RD);
-
-  NodeId Sib = DA.Addr->getSibling();
-  if (RD == 0) {
-    assert(Sib == 0);
-    return;
-  }
-
-  // Update the reaching def node and remove DA from the sibling list.
-  auto RDA = addr<DefNode*>(RD);
-  auto TA = addr<DefNode*>(RDA.Addr->getReachedDef());
-  if (TA.Id == DA.Id) {
-    // If DA is the first reached def, just update the RD's reached def
-    // to the DA's sibling.
-    RDA.Addr->setReachedDef(Sib);
-  } else {
-    // Otherwise, traverse the sibling list of the reached defs and remove
-    // DA from it.
-    while (TA.Id != 0) {
-      NodeId S = TA.Addr->getSibling();
-      if (S == DA.Id) {
-        TA.Addr->setSibling(Sib);
-        break;
-      }
-      TA = addr<DefNode*>(S);
-    }
-  }
-
-  // Splice the DA's reached defs into the RDA's reached def chain.
-  if (!ReachedDefs.empty()) {
-    auto Last = NodeAddr<DefNode*>(ReachedDefs.back());
-    Last.Addr->setSibling(RDA.Addr->getReachedDef());
-    RDA.Addr->setReachedDef(ReachedDefs.front().Id);
-  }
-  // Splice the DA's reached uses into the RDA's reached use chain.
-  if (!ReachedUses.empty()) {
-    auto Last = NodeAddr<UseNode*>(ReachedUses.back());
-    Last.Addr->setSibling(RDA.Addr->getReachedUse());
-    RDA.Addr->setReachedUse(ReachedUses.front().Id);
-  }
-}

lib/Target/Hexagon/RDFLiveness.h

-//===--- RDFLiveness.h ----------------------------------------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// Recalculate the liveness information given a data flow graph.
-// This includes block live-ins and kill flags.
-
-#ifndef RDF_LIVENESS_H
-#define RDF_LIVENESS_H
-
-#include "RDFGraph.h"
-#include "llvm/ADT/DenseMap.h"
-#include <map>
-
-using namespace llvm;
-
-namespace llvm {
-  class MachineBasicBlock;
-  class MachineFunction;
-  class MachineRegisterInfo;
-  class TargetRegisterInfo;
-  class MachineDominatorTree;
-  class MachineDominanceFrontier;
-
-namespace rdf {
-  struct Liveness {
-  public:
-    // This is really a std::map, except that it provides a non-trivial
-    // default constructor to the element accessed via [].
-    struct LiveMapType {
-      LiveMapType(const PhysicalRegisterInfo &pri) : Empty(pri) {}
-
-      RegisterAggr &operator[] (MachineBasicBlock *B) {
-        return Map.emplace(B, Empty).first->second;
-      }
-    private:
-      RegisterAggr Empty;
-      std::map<MachineBasicBlock*,RegisterAggr> Map;
-    };
-
-    typedef std::pair<NodeId,LaneBitmask> NodeRef;
-    typedef std::set<NodeRef> NodeRefSet;
-    // RegisterId in RefMap must be normalized.
-    typedef std::map<RegisterId,NodeRefSet> RefMap;
-
-    Liveness(MachineRegisterInfo &mri, const DataFlowGraph &g)
-      : DFG(g), TRI(g.getTRI()), PRI(g.getPRI()), MDT(g.getDT()),
-        MDF(g.getDF()), LiveMap(g.getPRI()), Empty(),
-        NoRegs(g.getPRI()), Trace(false) {}
-
-    NodeList getAllReachingDefs(RegisterRef RefRR, NodeAddr<RefNode*> RefA,
-        bool TopShadows, bool FullChain, const RegisterAggr &DefRRs);
-    NodeList getAllReachingDefs(NodeAddr<RefNode*> RefA) {
-      return getAllReachingDefs(RefA.Addr->getRegRef(DFG), RefA, false,
-                                false, NoRegs);
-    }
-    NodeList getAllReachingDefs(RegisterRef RefRR, NodeAddr<RefNode*> RefA) {
-      return getAllReachingDefs(RefRR, RefA, false, false, NoRegs);
-    }
-    NodeSet getAllReachedUses(RegisterRef RefRR, NodeAddr<DefNode*> DefA,
-        const RegisterAggr &DefRRs);
-    NodeSet getAllReachedUses(RegisterRef RefRR, NodeAddr<DefNode*> DefA) {
-      return getAllReachedUses(RefRR, DefA, NoRegs);
-    }
-
-    std::pair<NodeSet,bool> getAllReachingDefsRec(RegisterRef RefRR,
-        NodeAddr<RefNode*> RefA, NodeSet &Visited, const NodeSet &Defs);
-
-    NodeAddr<RefNode*> getNearestAliasedRef(RegisterRef RefRR,
-        NodeAddr<InstrNode*> IA);
-
-    LiveMapType &getLiveMap() { return LiveMap; }
-    const LiveMapType &getLiveMap() const { return LiveMap; }
-    const RefMap &getRealUses(NodeId P) const {
-      auto F = RealUseMap.find(P);
-      return F == RealUseMap.end() ? Empty : F->second;
-    }
-
-    void computePhiInfo();
-    void computeLiveIns();
-    void resetLiveIns();
-    void resetKills();
-    void resetKills(MachineBasicBlock *B);
-
-    void trace(bool T) { Trace = T; }
-
-  private:
-    const DataFlowGraph &DFG;
-    const TargetRegisterInfo &TRI;
-    const PhysicalRegisterInfo &PRI;
-    const MachineDominatorTree &MDT;
-    const MachineDominanceFrontier &MDF;
-    LiveMapType LiveMap;
-    const RefMap Empty;
-    const RegisterAggr NoRegs;
-    bool Trace;
-
-    // Cache of mapping from node ids (for RefNodes) to the containing
-    // basic blocks. Not computing it each time for each node reduces
-    // the liveness calculation time by a large fraction.
-    typedef DenseMap<NodeId,MachineBasicBlock*> NodeBlockMap;
-    NodeBlockMap NBMap;
-
-    // Phi information:
-    //
-    // RealUseMap
-    // map: NodeId -> (map: RegisterId -> NodeRefSet)
-    //      phi id -> (map: register -> set of reached non-phi uses)
-    std::map<NodeId, RefMap> RealUseMap;
-
-    // Inverse iterated dominance frontier.
-    std::map<MachineBasicBlock*,std::set<MachineBasicBlock*>> IIDF;
-
-    // Live on entry.
-    std::map<MachineBasicBlock*,RefMap> PhiLON;
-
-    // Phi uses are considered to be located at the end of the block that
-    // they are associated with. The reaching def of a phi use dominates the
-    // block that the use corresponds to, but not the block that contains
-    // the phi itself. To include these uses in the liveness propagation (up
-    // the dominator tree), create a map: block -> set of uses live on exit.
-    std::map<MachineBasicBlock*,RefMap> PhiLOX;
-
-    MachineBasicBlock *getBlockWithRef(NodeId RN) const;
-    void traverse(MachineBasicBlock *B, RefMap &LiveIn);
-    void emptify(RefMap &M);
-
-    std::pair<NodeSet,bool> getAllReachingDefsRecImpl(RegisterRef RefRR,
-        NodeAddr<RefNode*> RefA, NodeSet &Visited, const NodeSet &Defs,
-        unsigned Nest, unsigned MaxNest);
-  };
-} // namespace rdf
-} // namespace llvm
-
-#endif // RDF_LIVENESS_H

lib/Target/Hexagon/RDFLiveness.cpp

-//===--- RDFLiveness.cpp --------------------------------------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// Computation of the liveness information from the data-flow graph.
-//
-// The main functionality of this code is to compute block live-in
-// information. With the live-in information in place, the placement
-// of kill flags can also be recalculated.
-//
-// The block live-in calculation is based on the ideas from the following
-// publication:
-//
-// Dibyendu Das, Ramakrishna Upadrasta, Benoit Dupont de Dinechin.
-// "Efficient Liveness Computation Using Merge Sets and DJ-Graphs."
-// ACM Transactions on Architecture and Code Optimization, Association for
-// Computing Machinery, 2012, ACM TACO Special Issue on "High-Performance
-// and Embedded Architectures and Compilers", 8 (4),
-// <10.1145/2086696.2086706>. <hal-00647369>
-//
-#include "RDFGraph.h"
-#include "RDFLiveness.h"
-#include "llvm/ADT/SetVector.h"
-#include "llvm/CodeGen/MachineBasicBlock.h"
-#include "llvm/CodeGen/MachineDominanceFrontier.h"
-#include "llvm/CodeGen/MachineDominators.h"
-#include "llvm/CodeGen/MachineFunction.h"
-#include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/Support/CommandLine.h"
-#include "llvm/Target/TargetRegisterInfo.h"
-
-using namespace llvm;
-using namespace rdf;
-
-static cl::opt<unsigned> MaxRecNest("rdf-liveness-max-rec", cl::init(25),
-  cl::Hidden, cl::desc("Maximum recursion level"));
-
-namespace llvm {
-namespace rdf {
-  template<>
-  raw_ostream &operator<< (raw_ostream &OS, const Print<Liveness::RefMap> &P) {
-    OS << '{';
-    for (auto &I : P.Obj) {
-      OS << ' ' << PrintReg(I.first, &P.G.getTRI()) << '{';
-      for (auto J = I.second.begin(), E = I.second.end(); J != E; ) {
-        OS << Print<NodeId>(J->first, P.G) << PrintLaneMaskOpt(J->second);
-        if (++J != E)
-          OS << ',';
-      }
-      OS << '}';
-    }
-    OS << " }";
-    return OS;
-  }
-} // namespace rdf
-} // namespace llvm
-
-// The order in the returned sequence is the order of reaching defs in the
-// upward traversal: the first def is the closest to the given reference RefA,
-// the next one is further up, and so on.
-// The list ends at a reaching phi def, or when the reference from RefA is
-// covered by the defs in the list (see FullChain).
-// This function provides two modes of operation:
-// (1) Returning the sequence of reaching defs for a particular reference
-// node. This sequence will terminate at the first phi node [1].
-// (2) Returning a partial sequence of reaching defs, where the final goal
-// is to traverse past phi nodes to the actual defs arising from the code
-// itself.
-// In mode (2), the register reference for which the search was started
-// may be different from the reference node RefA, for which this call was
-// made, hence the argument RefRR, which holds the original register.
-// Also, some definitions may have already been encountered in a previous
-// call that will influence register covering. The register references
-// already defined are passed in through DefRRs.
-// In mode (1), the "continuation" considerations do not apply, and the
-// RefRR is the same as the register in RefA, and the set DefRRs is empty.
-//
-// [1] It is possible for multiple phi nodes to be included in the returned
-// sequence:
-//   SubA = phi ...
-//   SubB = phi ...
-//   ...  = SuperAB(rdef:SubA), SuperAB"(rdef:SubB)
-// However, these phi nodes are independent from one another in terms of
-// the data-flow.
-
-NodeList Liveness::getAllReachingDefs(RegisterRef RefRR,
-      NodeAddr<RefNode*> RefA, bool TopShadows, bool FullChain,
-      const RegisterAggr &DefRRs) {
-  NodeList RDefs; // Return value.
-  SetVector<NodeId> DefQ;
-  SetVector<NodeId> Owners;
-
-  // Dead defs will be treated as if they were live, since they are actually
-  // on the data-flow path. They cannot be ignored because even though they
-  // do not generate meaningful values, they still modify registers.
-
-  // If the reference is undefined, there is nothing to do.
-  if (RefA.Addr->getFlags() & NodeAttrs::Undef)
-    return RDefs;
-
-  // The initial queue should not have reaching defs for shadows. The
-  // whole point of a shadow is that it will have a reaching def that
-  // is not aliased to the reaching defs of the related shadows.
-  NodeId Start = RefA.Id;
-  auto SNA = DFG.addr<RefNode*>(Start);
-  if (NodeId RD = SNA.Addr->getReachingDef())
-    DefQ.insert(RD);
-  if (TopShadows) {
-    for (auto S : DFG.getRelatedRefs(RefA.Addr->getOwner(DFG), RefA))
-      if (NodeId RD = NodeAddr<RefNode*>(S).Addr->getReachingDef())
-        DefQ.insert(RD);
-  }
-
-  // Collect all the reaching defs, going up until a phi node is encountered,
-  // or there are no more reaching defs. From this set, the actual set of
-  // reaching defs will be selected.
-  // The traversal upwards must go on until a covering def is encountered.
-  // It is possible that a collection of non-covering (individually) defs
-  // will be sufficient, but keep going until a covering one is found.
-  for (unsigned i = 0; i < DefQ.size(); ++i) {
-    auto TA = DFG.addr<DefNode*>(DefQ[i]);
-    if (TA.Addr->getFlags() & NodeAttrs::PhiRef)
-      continue;
-    // Stop at the covering/overwriting def of the initial register reference.
-    RegisterRef RR = TA.Addr->getRegRef(DFG);
-    if (!DFG.IsPreservingDef(TA))
-      if (RegisterAggr::isCoverOf(RR, RefRR, PRI))
-        continue;
-    // Get the next level of reaching defs. This will include multiple
-    // reaching defs for shadows.
-    for (auto S : DFG.getRelatedRefs(TA.Addr->getOwner(DFG), TA))
-      if (NodeId RD = NodeAddr<RefNode*>(S).Addr->getReachingDef())
-        DefQ.insert(RD);
-  }
-
-  // Remove all non-phi defs that are not aliased to RefRR, and collect
-  // the owners of the remaining defs.
-  SetVector<NodeId> Defs;
-  for (NodeId N : DefQ) {
-    auto TA = DFG.addr<DefNode*>(N);
-    bool IsPhi = TA.Addr->getFlags() & NodeAttrs::PhiRef;
-    if (!IsPhi && !PRI.alias(RefRR, TA.Addr->getRegRef(DFG)))
-      continue;
-    Defs.insert(TA.Id);
-    Owners.insert(TA.Addr->getOwner(DFG).Id);
-  }
-
-  // Return the MachineBasicBlock containing a given instruction.
-  auto Block = [this] (NodeAddr<InstrNode*> IA) -> MachineBasicBlock* {
-    if (IA.Addr->getKind() == NodeAttrs::Stmt)
-      return NodeAddr<StmtNode*>(IA).Addr->getCode()->getParent();
-    assert(IA.Addr->getKind() == NodeAttrs::Phi);
-    NodeAddr<PhiNode*> PA = IA;
-    NodeAddr<BlockNode*> BA = PA.Addr->getOwner(DFG);
-    return BA.Addr->getCode();
-  };
-  // Less(A,B) iff instruction A is further down in the dominator tree than B.
-  auto Less = [&Block,this] (NodeId A, NodeId B) -> bool {
-    if (A == B)
-      return false;
-    auto OA = DFG.addr<InstrNode*>(A), OB = DFG.addr<InstrNode*>(B);
-    MachineBasicBlock *BA = Block(OA), *BB = Block(OB);
-    if (BA != BB)
-      return MDT.dominates(BB, BA);
-    // They are in the same block.
-    bool StmtA = OA.Addr->getKind() == NodeAttrs::Stmt;
-    bool StmtB = OB.Addr->getKind() == NodeAttrs::Stmt;
-    if (StmtA) {
-      if (!StmtB)   // OB is a phi and phis dominate statements.
-        return true;
-      MachineInstr *CA = NodeAddr<StmtNode*>(OA).Addr->getCode();
-      MachineInstr *CB = NodeAddr<StmtNode*>(OB).Addr->getCode();
-      // The order must be linear, so tie-break such equalities.
-      if (CA == CB)
-        return A < B;
-      return MDT.dominates(CB, CA);
-    } else {
-      // OA is a phi.
-      if (StmtB)
-        return false;
-      // Both are phis. There is no ordering between phis (in terms of
-      // the data-flow), so tie-break this via node id comparison.
-      return A < B;
-    }
-  };
-
-  std::vector<NodeId> Tmp(Owners.begin(), Owners.end());
-  std::sort(Tmp.begin(), Tmp.end(), Less);
-
-  // The vector is a list of instructions, so that defs coming from
-  // the same instruction don't need to be artificially ordered.
-  // Then, when computing the initial segment, and iterating over an
-  // instruction, pick the defs that contribute to the covering (i.e. is
-  // not covered by previously added defs). Check the defs individually,
-  // i.e. first check each def if is covered or not (without adding them
-  // to the tracking set), and then add all the selected ones.
-
-  // The reason for this is this example:
-  // *d1<A>, *d2<B>, ... Assume A and B are aliased (can happen in phi nodes).
-  // *d3<C>              If A \incl BuC, and B \incl AuC, then *d2 would be
-  //                     covered if we added A first, and A would be covered
-  //                     if we added B first.
-
-  RegisterAggr RRs(DefRRs);
-
-  auto DefInSet = [&Defs] (NodeAddr<RefNode*> TA) -> bool {
-    return TA.Addr->getKind() == NodeAttrs::Def &&
-           Defs.count(TA.Id);
-  };
-  for (NodeId T : Tmp) {
-    if (!FullChain && RRs.hasCoverOf(RefRR))
-      break;
-    auto TA = DFG.addr<InstrNode*>(T);
-    bool IsPhi = DFG.IsCode<NodeAttrs::Phi>(TA);
-    NodeList Ds;
-    for (NodeAddr<DefNode*> DA : TA.Addr->members_if(DefInSet, DFG)) {
-      RegisterRef QR = DA.Addr->getRegRef(DFG);
-      // Add phi defs even if they are covered by subsequent defs. This is
-      // for cases where the reached use is not covered by any of the defs
-      // encountered so far: the phi def is needed to expose the liveness
-      // of that use to the entry of the block.
-      // Example:
-      //   phi d1<R3>(,d2,), ...  Phi def d1 is covered by d2.
-      //   d2<R3>(d1,,u3), ...
-      //   ..., u3<D1>(d2)        This use needs to be live on entry.
-      if (FullChain || IsPhi || !RRs.hasCoverOf(QR))
-        Ds.push_back(DA);
-    }
-    RDefs.insert(RDefs.end(), Ds.begin(), Ds.end());
-    for (NodeAddr<DefNode*> DA : Ds) {
-      // When collecting a full chain of definitions, do not consider phi
-      // defs to actually define a register.
-      uint16_t Flags = DA.Addr->getFlags();
-      if (!FullChain || !(Flags & NodeAttrs::PhiRef))
-        if (!(Flags & NodeAttrs::Preserving)) // Don't care about Undef here.
-          RRs.insert(DA.Addr->getRegRef(DFG));
-    }
-  }
-
-  auto DeadP = [](const NodeAddr<DefNode*> DA) -> bool {
-    return DA.Addr->getFlags() & NodeAttrs::Dead;
-  };
-  RDefs.resize(std::distance(RDefs.begin(), remove_if(RDefs, DeadP)));
-
-  return RDefs;
-}
-
-
-std::pair<NodeSet,bool>
-Liveness::getAllReachingDefsRec(RegisterRef RefRR, NodeAddr<RefNode*> RefA,
-      NodeSet &Visited, const NodeSet &Defs) {
-  return getAllReachingDefsRecImpl(RefRR, RefA, Visited, Defs, 0, MaxRecNest);
-}
-
-
-std::pair<NodeSet,bool>
-Liveness::getAllReachingDefsRecImpl(RegisterRef RefRR, NodeAddr<RefNode*> RefA,
-      NodeSet &Visited, const NodeSet &Defs, unsigned Nest, unsigned MaxNest) {
-  if (Nest > MaxNest)
-    return { NodeSet(), false };
-  // Collect all defined registers. Do not consider phis to be defining
-  // anything, only collect "real" definitions.
-  RegisterAggr DefRRs(PRI);
-  for (NodeId D : Defs) {
-    const auto DA = DFG.addr<const DefNode*>(D);
-    if (!(DA.Addr->getFlags() & NodeAttrs::PhiRef))
-      DefRRs.insert(DA.Addr->getRegRef(DFG));
-  }
-
-  NodeList RDs = getAllReachingDefs(RefRR, RefA, false, true, DefRRs);
-  if (RDs.empty())
-    return { Defs, true };
-
-  // Make a copy of the preexisting definitions and add the newly found ones.
-  NodeSet TmpDefs = Defs;
-  for (NodeAddr<NodeBase*> R : RDs)
-    TmpDefs.insert(R.Id);
-
-  NodeSet Result = Defs;
-
-  for (NodeAddr<DefNode*> DA : RDs) {
-    Result.insert(DA.Id);
-    if (!(DA.Addr->getFlags() & NodeAttrs::PhiRef))
-      continue;
-    NodeAddr<PhiNode*> PA = DA.Addr->getOwner(DFG);
-    if (Visited.count(PA.Id))
-      continue;
-    Visited.insert(PA.Id);
-    // Go over all phi uses and get the reaching defs for each use.
-    for (auto U : PA.Addr->members_if(DFG.IsRef<NodeAttrs::Use>, DFG)) {
-      const auto &T = getAllReachingDefsRecImpl(RefRR, U, Visited, TmpDefs,
-                                                Nest+1, MaxNest);
-      if (!T.second)
-        return { T.first, false };
-      Result.insert(T.first.begin(), T.first.end());
-    }
-  }
-
-  return { Result, true };
-}
-
-/// Find the nearest ref node aliased to RefRR, going upwards in the data
-/// flow, starting from the instruction immediately preceding Inst.
-NodeAddr<RefNode*> Liveness::getNearestAliasedRef(RegisterRef RefRR,
-      NodeAddr<InstrNode*> IA) {
-  NodeAddr<BlockNode*> BA = IA.Addr->getOwner(DFG);
-  NodeList Ins = BA.Addr->members(DFG);
-  NodeId FindId = IA.Id;
-  auto E = Ins.rend();
-  auto B = std::find_if(Ins.rbegin(), E,
-                        [FindId] (const NodeAddr<InstrNode*> T) {
-                          return T.Id == FindId;
-                        });
-  // Do not scan IA (which is what B would point to).
-  if (B != E)
-    ++B;
-
-  do {
-    // Process the range of instructions from B to E.
-    for (NodeAddr<InstrNode*> I : make_range(B, E)) {
-      NodeList Refs = I.Addr->members(DFG);
-      NodeAddr<RefNode*> Clob, Use;
-      // Scan all the refs in I aliased to RefRR, and return the one that
-      // is the closest to the output of I, i.e. def > clobber > use.
-      for (NodeAddr<RefNode*> R : Refs) {
-        if (!PRI.alias(R.Addr->getRegRef(DFG), RefRR))
-          continue;
-        if (DFG.IsDef(R)) {
-          // If it's a non-clobbering def, just return it.
-          if (!(R.Addr->getFlags() & NodeAttrs::Clobbering))
-            return R;
-          Clob = R;
-        } else {
-          Use = R;
-        }
-      }
-      if (Clob.Id != 0)
-        return Clob;
-      if (Use.Id != 0)
-        return Use;
-    }
-
-    // Go up to the immediate dominator, if any.
-    MachineBasicBlock *BB = BA.Addr->getCode();
-    BA = NodeAddr<BlockNode*>();
-    if (MachineDomTreeNode *N = MDT.getNode(BB)) {
-      if ((N = N->getIDom()))
-        BA = DFG.findBlock(N->getBlock());
-    }
-    if (!BA.Id)
-      break;
-
-    Ins = BA.Addr->members(DFG);
-    B = Ins.rbegin();
-    E = Ins.rend();
-  } while (true);
-
-  return NodeAddr<RefNode*>();
-}
-
-
-NodeSet Liveness::getAllReachedUses(RegisterRef RefRR,
-      NodeAddr<DefNode*> DefA, const RegisterAggr &DefRRs) {
-  NodeSet Uses;
-
-  // If the original register is already covered by all the intervening
-  // defs, no more uses can be reached.
-  if (DefRRs.hasCoverOf(RefRR))
-    return Uses;
-
-  // Add all directly reached uses.
-  // If the def is dead, it does not provide a value for any use.
-  bool IsDead = DefA.Addr->getFlags() & NodeAttrs::Dead;
-  NodeId U = !IsDead ? DefA.Addr->getReachedUse() : 0;
-  while (U != 0) {
-    auto UA = DFG.addr<UseNode*>(U);
-    if (!(UA.Addr->getFlags() & NodeAttrs::Undef)) {
-      RegisterRef UR = UA.Addr->getRegRef(DFG);
-      if (PRI.alias(RefRR, UR) && !DefRRs.hasCoverOf(UR))
-        Uses.insert(U);
-    }
-    U = UA.Addr->getSibling();
-  }
-
-  // Traverse all reached defs. This time dead defs cannot be ignored.
-  for (NodeId D = DefA.Addr->getReachedDef(), NextD; D != 0; D = NextD) {
-    auto DA = DFG.addr<DefNode*>(D);
-    NextD = DA.Addr->getSibling();
-    RegisterRef DR = DA.Addr->getRegRef(DFG);
-    // If this def is already covered, it cannot reach anything new.
-    // Similarly, skip it if it is not aliased to the interesting register.
-    if (DefRRs.hasCoverOf(DR) || !PRI.alias(RefRR, DR))
-      continue;
-    NodeSet T;
-    if (DFG.IsPreservingDef(DA)) {
-      // If it is a preserving def, do not update the set of intervening defs.
-      T = getAllReachedUses(RefRR, DA, DefRRs);
-    } else {
-      RegisterAggr NewDefRRs = DefRRs;
-      NewDefRRs.insert(DR);
-      T = getAllReachedUses(RefRR, DA, NewDefRRs);
-    }
-    Uses.insert(T.begin(), T.end());
-  }
-  return Uses;
-}
-
-
-void Liveness::computePhiInfo() {
-  RealUseMap.clear();
-
-  NodeList Phis;
-  NodeAddr<FuncNode*> FA = DFG.getFunc();
-  NodeList Blocks = FA.Addr->members(DFG);
-  for (NodeAddr<BlockNode*> BA : Blocks) {
-    auto Ps = BA.Addr->members_if(DFG.IsCode<NodeAttrs::Phi>, DFG);
-    Phis.insert(Phis.end(), Ps.begin(), Ps.end());
-  }
-
-  // phi use -> (map: reaching phi -> set of registers defined in between)
-  std::map<NodeId,std::map<NodeId,RegisterAggr>> PhiUp;
-  std::vector<NodeId> PhiUQ;  // Work list of phis for upward propagation.
-  std::map<NodeId,RegisterAggr> PhiDRs;  // Phi -> registers defined by it.
-
-  // Go over all phis.
-  for (NodeAddr<PhiNode*> PhiA : Phis) {
-    // Go over all defs and collect the reached uses that are non-phi uses
-    // (i.e. the "real uses").
-    RefMap &RealUses = RealUseMap[PhiA.Id];
-    NodeList PhiRefs = PhiA.Addr->members(DFG);
-
-    // Have a work queue of defs whose reached uses need to be found.
-    // For each def, add to the queue all reached (non-phi) defs.
-    SetVector<NodeId> DefQ;
-    NodeSet PhiDefs;
-    RegisterAggr DRs(PRI);
-    for (NodeAddr<RefNode*> R : PhiRefs) {
-      if (!DFG.IsRef<NodeAttrs::Def>(R))
-        continue;
-      DRs.insert(R.Addr->getRegRef(DFG));
-      DefQ.insert(R.Id);
-      PhiDefs.insert(R.Id);
-    }
-    PhiDRs.insert(std::make_pair(PhiA.Id, DRs));
-
-    // Collect the super-set of all possible reached uses. This set will
-    // contain all uses reached from this phi, either directly from the
-    // phi defs, or (recursively) via non-phi defs reached by the phi defs.
-    // This set of uses will later be trimmed to only contain these uses that
-    // are actually reached by the phi defs.
-    for (unsigned i = 0; i < DefQ.size(); ++i) {
-      NodeAddr<DefNode*> DA = DFG.addr<DefNode*>(DefQ[i]);
-      // Visit all reached uses. Phi defs should not really have the "dead"
-      // flag set, but check it anyway for consistency.
-      bool IsDead = DA.Addr->getFlags() & NodeAttrs::Dead;
-      NodeId UN = !IsDead ? DA.Addr->getReachedUse() : 0;
-      while (UN != 0) {
-        NodeAddr<UseNode*> A = DFG.addr<UseNode*>(UN);
-        uint16_t F = A.Addr->getFlags();
-        if ((F & (NodeAttrs::Undef | NodeAttrs::PhiRef)) == 0) {
-          RegisterRef R = PRI.normalize(A.Addr->getRegRef(DFG));
-          RealUses[R.Reg].insert({A.Id,R.Mask});
-        }
-        UN = A.Addr->getSibling();
-      }
-      // Visit all reached defs, and add them to the queue. These defs may
-      // override some of the uses collected here, but that will be handled
-      // later.
-      NodeId DN = DA.Addr->getReachedDef();
-      while (DN != 0) {
-        NodeAddr<DefNode*> A = DFG.addr<DefNode*>(DN);
-        for (auto T : DFG.getRelatedRefs(A.Addr->getOwner(DFG), A)) {
-          uint16_t Flags = NodeAddr<DefNode*>(T).Addr->getFlags();
-          // Must traverse the reached-def chain. Consider:
-          //   def(D0) -> def(R0) -> def(R0) -> use(D0)
-          // The reachable use of D0 passes through a def of R0.
-          if (!(Flags & NodeAttrs::PhiRef))
-            DefQ.insert(T.Id);
-        }
-        DN = A.Addr->getSibling();
-      }
-    }
-    // Filter out these uses that appear to be reachable, but really
-    // are not. For example:
-    //
-    // R1:0 =          d1
-    //      = R1:0     u2     Reached by d1.
-    //   R0 =          d3
-    //      = R1:0     u4     Still reached by d1: indirectly through
-    //                        the def d3.
-    //   R1 =          d5
-    //      = R1:0     u6     Not reached by d1 (covered collectively
-    //                        by d3 and d5), but following reached
-    //                        defs and uses from d1 will lead here.
-    auto InPhiDefs = [&PhiDefs] (NodeAddr<DefNode*> DA) -> bool {
-      return PhiDefs.count(DA.Id);
-    };
-    for (auto UI = RealUses.begin(), UE = RealUses.end(); UI != UE; ) {
-      // For each reached register UI->first, there is a set UI->second, of
-      // uses of it. For each such use, check if it is reached by this phi,
-      // i.e. check if the set of its reaching uses intersects the set of
-      // this phi's defs.
-      NodeRefSet &Uses = UI->second;
-      for (auto I = Uses.begin(), E = Uses.end(); I != E; ) {
-        auto UA = DFG.addr<UseNode*>(I->first);
-        // Undef flag is checked above.
-        assert((UA.Addr->getFlags() & NodeAttrs::Undef) == 0);
-        RegisterRef R(UI->first, I->second);
-        NodeList RDs = getAllReachingDefs(R, UA);
-        // If none of the reaching defs of R are from this phi, remove this
-        // use of R.
-        I = any_of(RDs, InPhiDefs) ? std::next(I) : Uses.erase(I);
-      }
-      UI = Uses.empty() ? RealUses.erase(UI) : std::next(UI);
-    }
-
-    // If this phi reaches some "real" uses, add it to the queue for upward
-    // propagation.
-    if (!RealUses.empty())
-      PhiUQ.push_back(PhiA.Id);
-
-    // Go over all phi uses and check if the reaching def is another phi.
-    // Collect the phis that are among the reaching defs of these uses.
-    // While traversing the list of reaching defs for each phi use, accumulate
-    // the set of registers defined between this phi (PhiA) and the owner phi
-    // of the reaching def.
-    NodeSet SeenUses;
-
-    for (auto I : PhiRefs) {
-      if (!DFG.IsRef<NodeAttrs::Use>(I) || SeenUses.count(I.Id))
-        continue;
-      NodeAddr<PhiUseNode*> PUA = I;
-      if (PUA.Addr->getReachingDef() == 0)
-        continue;
-
-      RegisterRef UR = PUA.Addr->getRegRef(DFG);
-      NodeList Ds = getAllReachingDefs(UR, PUA, true, false, NoRegs);
-      RegisterAggr DefRRs(PRI);
-
-      for (NodeAddr<DefNode*> D : Ds) {
-        if (D.Addr->getFlags() & NodeAttrs::PhiRef) {
-          NodeId RP = D.Addr->getOwner(DFG).Id;
-          std::map<NodeId,RegisterAggr> &M = PhiUp[PUA.Id];
-          auto F = M.find(RP);
-          if (F == M.end())
-            M.insert(std::make_pair(RP, DefRRs));
-          else
-            F->second.insert(DefRRs);
-        }
-        DefRRs.insert(D.Addr->getRegRef(DFG));
-      }
-
-      for (NodeAddr<PhiUseNode*> T : DFG.getRelatedRefs(PhiA, PUA))
-        SeenUses.insert(T.Id);
-    }
-  }
-
-  if (Trace) {
-    dbgs() << "Phi-up-to-phi map with intervening defs:\n";
-    for (auto I : PhiUp) {
-      dbgs() << "phi " << Print<NodeId>(I.first, DFG) << " -> {";
-      for (auto R : I.second)
-        dbgs() << ' ' << Print<NodeId>(R.first, DFG)
-               << Print<RegisterAggr>(R.second, DFG);
-      dbgs() << " }\n";
-    }
-  }
-
-  // Propagate the reached registers up in the phi chain.
-  //
-  // The following type of situation needs careful handling:
-  //
-  //   phi d1<R1:0>  (1)
-  //        |
-  //   ... d2<R1>
-  //        |
-  //   phi u3<R1:0>  (2)
-  //        |
-  //   ... u4<R1>
-  //
-  // The phi node (2) defines a register pair R1:0, and reaches a "real"
-  // use u4 of just R1. The same phi node is also known to reach (upwards)
-  // the phi node (1). However, the use u4 is not reached by phi (1),
-  // because of the intervening definition d2 of R1. The data flow between
-  // phis (1) and (2) is restricted to R1:0 minus R1, i.e. R0.
-  //
-  // When propagating uses up the phi chains, get the all reaching defs
-  // for a given phi use, and traverse the list until the propagated ref
-  // is covered, or until reaching the final phi. Only assume that the
-  // reference reaches the phi in the latter case.
-
-  for (unsigned i = 0; i < PhiUQ.size(); ++i) {
-    auto PA = DFG.addr<PhiNode*>(PhiUQ[i]);
-    NodeList PUs = PA.Addr->members_if(DFG.IsRef<NodeAttrs::Use>, DFG);
-    RefMap &RUM = RealUseMap[PA.Id];
-
-    for (NodeAddr<UseNode*> UA : PUs) {
-      std::map<NodeId,RegisterAggr> &PUM = PhiUp[UA.Id];
-      RegisterRef UR = PRI.normalize(UA.Addr->getRegRef(DFG));
-      for (const std::pair<NodeId,RegisterAggr> &P : PUM) {
-        bool Changed = false;
-        const RegisterAggr &MidDefs = P.second;
-
-        // Collect the set PropUp of uses that are reached by the current
-        // phi PA, and are not covered by any intervening def between the
-        // currently visited use UA and the the upward phi P.
-
-        if (MidDefs.hasCoverOf(UR))
-          continue;
-
-        // General algorithm:
-        //   for each (R,U) : U is use node of R, U is reached by PA
-        //     if MidDefs does not cover (R,U)
-        //       then add (R-MidDefs,U) to RealUseMap[P]
-        //
-        for (const std::pair<RegisterId,NodeRefSet> &T : RUM) {
-          RegisterRef R(T.first);
-          // The current phi (PA) could be a phi for a regmask. It could
-          // reach a whole variety of uses that are not related to the
-          // specific upward phi (P.first).
-          const RegisterAggr &DRs = PhiDRs.at(P.first);
-          if (!DRs.hasAliasOf(R))
-            continue;
-          R = DRs.intersectWith(R);
-          for (std::pair<NodeId,LaneBitmask> V : T.second) {
-            LaneBitmask M = R.Mask & V.second;
-            if (M.none())
-              continue;
-            if (RegisterRef SS = MidDefs.clearIn(RegisterRef(R.Reg, M))) {
-              NodeRefSet &RS = RealUseMap[P.first][SS.Reg];
-              Changed |= RS.insert({V.first,SS.Mask}).second;
-            }
-          }
-        }
-
-        if (Changed)
-          PhiUQ.push_back(P.first);
-      }
-    }
-  }
-
-  if (Trace) {
-    dbgs() << "Real use map:\n";
-    for (auto I : RealUseMap) {
-      dbgs() << "phi " << Print<NodeId>(I.first, DFG);
-      NodeAddr<PhiNode*> PA = DFG.addr<PhiNode*>(I.first);
-      NodeList Ds = PA.Addr->members_if(DFG.IsRef<NodeAttrs::Def>, DFG);
-      if (!Ds.empty()) {
-        RegisterRef RR = NodeAddr<DefNode*>(Ds[0]).Addr->getRegRef(DFG);
-        dbgs() << '<' << Print<RegisterRef>(RR, DFG) << '>';
-      } else {
-        dbgs() << "<noreg>";
-      }
-      dbgs() << " -> " << Print<RefMap>(I.second, DFG) << '\n';
-    }
-  }
-}
-
-
-void Liveness::computeLiveIns() {
-  // Populate the node-to-block map. This speeds up the calculations
-  // significantly.
-  NBMap.clear();
-  for (NodeAddr<BlockNode*> BA : DFG.getFunc().Addr->members(DFG)) {
-    MachineBasicBlock *BB = BA.Addr->getCode();
-    for (NodeAddr<InstrNode*> IA : BA.Addr->members(DFG)) {
-      for (NodeAddr<RefNode*> RA : IA.Addr->members(DFG))
-        NBMap.insert(std::make_pair(RA.Id, BB));
-      NBMap.insert(std::make_pair(IA.Id, BB));
-    }
-  }
-
-  MachineFunction &MF = DFG.getMF();
-
-  // Compute IDF first, then the inverse.
-  decltype(IIDF) IDF;
-  for (MachineBasicBlock &B : MF) {
-    auto F1 = MDF.find(&B);
-    if (F1 == MDF.end())
-      continue;
-    SetVector<MachineBasicBlock*> IDFB(F1->second.begin(), F1->second.end());
-    for (unsigned i = 0; i < IDFB.size(); ++i) {
-      auto F2 = MDF.find(IDFB[i]);
-      if (F2 != MDF.end())
-        IDFB.insert(F2->second.begin(), F2->second.end());
-    }
-    // Add B to the IDF(B). This will put B in the IIDF(B).
-    IDFB.insert(&B);
-    IDF[&B].insert(IDFB.begin(), IDFB.end());
-  }
-
-  for (auto I : IDF)
-    for (auto S : I.second)
-      IIDF[S].insert(I.first);
-
-  computePhiInfo();
-
-  NodeAddr<FuncNode*> FA = DFG.getFunc();
-  NodeList Blocks = FA.Addr->members(DFG);
-
-  // Build the phi live-on-entry map.
-  for (NodeAddr<BlockNode*> BA : Blocks) {
-    MachineBasicBlock *MB = BA.Addr->getCode();
-    RefMap &LON = PhiLON[MB];
-    for (auto P : BA.Addr->members_if(DFG.IsCode<NodeAttrs::Phi>, DFG))
-      for (const RefMap::value_type &S : RealUseMap[P.Id])
-        LON[S.first].insert(S.second.begin(), S.second.end());
-  }
-
-  if (Trace) {
-    dbgs() << "Phi live-on-entry map:\n";
-    for (auto &I : PhiLON)
-      dbgs() << "block #" << I.first->getNumber() << " -> "
-             << Print<RefMap>(I.second, DFG) << '\n';
-  }
-
-  // Build the phi live-on-exit map. Each phi node has some set of reached
-  // "real" uses. Propagate this set backwards into the block predecessors
-  // through the reaching defs of the corresponding phi uses.
-  for (NodeAddr<BlockNode*> BA : Blocks) {
-    NodeList Phis = BA.Addr->members_if(DFG.IsCode<NodeAttrs::Phi>, DFG);
-    for (NodeAddr<PhiNode*> PA : Phis) {
-      RefMap &RUs = RealUseMap[PA.Id];
-      if (RUs.empty())
-        continue;
-
-      NodeSet SeenUses;
-      for (auto U : PA.Addr->members_if(DFG.IsRef<NodeAttrs::Use>, DFG)) {
-        if (!SeenUses.insert(U.Id).second)
-          continue;
-        NodeAddr<PhiUseNode*> PUA = U;
-        if (PUA.Addr->getReachingDef() == 0)
-          continue;
-
-        // Each phi has some set (possibly empty) of reached "real" uses,
-        // that is, uses that are part of the compiled program. Such a use
-        // may be located in some farther block, but following a chain of
-        // reaching defs will eventually lead to this phi.
-        // Any chain of reaching defs may fork at a phi node, but there
-        // will be a path upwards that will lead to this phi. Now, this
-        // chain will need to fork at this phi, since some of the reached
-        // uses may have definitions joining in from multiple predecessors.
-        // For each reached "real" use, identify the set of reaching defs
-        // coming from each predecessor P, and add them to PhiLOX[P].
-        //
-        auto PrA = DFG.addr<BlockNode*>(PUA.Addr->getPredecessor());
-        RefMap &LOX = PhiLOX[PrA.Addr->getCode()];
-
-        for (const std::pair<RegisterId,NodeRefSet> &RS : RUs) {
-          // We need to visit each individual use.
-          for (std::pair<NodeId,LaneBitmask> P : RS.second) {
-            // Create a register ref corresponding to the use, and find
-            // all reaching defs starting from the phi use, and treating
-            // all related shadows as a single use cluster.
-            RegisterRef S(RS.first, P.second);
-            NodeList Ds = getAllReachingDefs(S, PUA, true, false, NoRegs);
-            for (NodeAddr<DefNode*> D : Ds)
-              LOX[S.Reg].insert({D.Id, S.Mask});
-          }
-        }
-
-        for (NodeAddr<PhiUseNode*> T : DFG.getRelatedRefs(PA, PUA))
-          SeenUses.insert(T.Id);
-      }  // for U : phi uses
-    }  // for P : Phis
-  }  // for B : Blocks
-
-  if (Trace) {
-    dbgs() << "Phi live-on-exit map:\n";
-    for (auto &I : PhiLOX)
-      dbgs() << "block #" << I.first->getNumber() << " -> "
-             << Print<RefMap>(I.second, DFG) << '\n';
-  }
-
-  RefMap LiveIn;
-  traverse(&MF.front(), LiveIn);
-
-  // Add function live-ins to the live-in set of the function entry block.
-  LiveMap[&MF.front()].insert(DFG.getLiveIns());
-
-  if (Trace) {
-    // Dump the liveness map
-    for (MachineBasicBlock &B : MF) {
-      std::vector<RegisterRef> LV;
-      for (auto I = B.livein_begin(), E = B.livein_end(); I != E; ++I)
-        LV.push_back(RegisterRef(I->PhysReg, I->LaneMask));
-      std::sort(LV.begin(), LV.end());
-      dbgs() << "BB#" << B.getNumber() << "\t rec = {";
-      for (auto I : LV)
-        dbgs() << ' ' << Print<RegisterRef>(I, DFG);
-      dbgs() << " }\n";
-      //dbgs() << "\tcomp = " << Print<RegisterAggr>(LiveMap[&B], DFG) << '\n';
-
-      LV.clear();
-      const RegisterAggr &LG = LiveMap[&B];
-      for (auto I = LG.rr_begin(), E = LG.rr_end(); I != E; ++I)
-        LV.push_back(*I);
-      std::sort(LV.begin(), LV.end());
-      dbgs() << "\tcomp = {";
-      for (auto I : LV)
-        dbgs() << ' ' << Print<RegisterRef>(I, DFG);
-      dbgs() << " }\n";
-
-    }
-  }
-}
-
-
-void Liveness::resetLiveIns() {
-  for (auto &B : DFG.getMF()) {
-    // Remove all live-ins.
-    std::vector<unsigned> T;
-    for (auto I = B.livein_begin(), E = B.livein_end(); I != E; ++I)
-      T.push_back(I->PhysReg);
-    for (auto I : T)
-      B.removeLiveIn(I);
-    // Add the newly computed live-ins.
-    const RegisterAggr &LiveIns = LiveMap[&B];
-    for (auto I = LiveIns.rr_begin(), E = LiveIns.rr_end(); I != E; ++I) {
-      RegisterRef R = *I;
-      B.addLiveIn({MCPhysReg(R.Reg), R.Mask});
-    }
-  }
-}
-
-
-void Liveness::resetKills() {
-  for (auto &B : DFG.getMF())
-    resetKills(&B);
-}
-
-
-void Liveness::resetKills(MachineBasicBlock *B) {
-  auto CopyLiveIns = [this] (MachineBasicBlock *B, BitVector &LV) -> void {
-    for (auto I : B->liveins()) {
-      MCSubRegIndexIterator S(I.PhysReg, &TRI);
-      if (!S.isValid()) {
-        LV.set(I.PhysReg);
-        continue;
-      }
-      do {
-        LaneBitmask M = TRI.getSubRegIndexLaneMask(S.getSubRegIndex());
-        if ((M & I.LaneMask).any())
-          LV.set(S.getSubReg());
-        ++S;
-      } while (S.isValid());
-    }
-  };
-
-  BitVector LiveIn(TRI.getNumRegs()), Live(TRI.getNumRegs());
-  CopyLiveIns(B, LiveIn);
-  for (auto SI : B->successors())
-    CopyLiveIns(SI, Live);
-
-  for (auto I = B->rbegin(), E = B->rend(); I != E; ++I) {
-    MachineInstr *MI = &*I;
-    if (MI->isDebugValue())
-      continue;
-
-    MI->clearKillInfo();
-    for (auto &Op : MI->operands()) {
-      // An implicit def of a super-register may not necessarily start a
-      // live range of it, since an implicit use could be used to keep parts
-      // of it live. Instead of analyzing the implicit operands, ignore
-      // implicit defs.
-      if (!Op.isReg() || !Op.isDef() || Op.isImplicit())
-        continue;
-      unsigned R = Op.getReg();
-      if (!TargetRegisterInfo::isPhysicalRegister(R))
-        continue;
-      for (MCSubRegIterator SR(R, &TRI, true); SR.isValid(); ++SR)
-        Live.reset(*SR);
-    }
-    for (auto &Op : MI->operands()) {
-      if (!Op.isReg() || !Op.isUse() || Op.isUndef())
-        continue;
-      unsigned R = Op.getReg();
-      if (!TargetRegisterInfo::isPhysicalRegister(R))
-        continue;
-      bool IsLive = false;
-      for (MCRegAliasIterator AR(R, &TRI, true); AR.isValid(); ++AR) {
-        if (!Live[*AR])
-          continue;
-        IsLive = true;
-        break;
-      }
-      if (!IsLive)
-        Op.setIsKill(true);
-      for (MCSubRegIterator SR(R, &TRI, true); SR.isValid(); ++SR)
-        Live.set(*SR);
-    }
-  }
-}
-
-
-// Helper function to obtain the basic block containing the reaching def
-// of the given use.
-MachineBasicBlock *Liveness::getBlockWithRef(NodeId RN) const {
-  auto F = NBMap.find(RN);
-  if (F != NBMap.end())
-    return F->second;
-  llvm_unreachable("Node id not in map");
-}
-
-
-void Liveness::traverse(MachineBasicBlock *B, RefMap &LiveIn) {
-  // The LiveIn map, for each (physical) register, contains the set of live
-  // reaching defs of that register that are live on entry to the associated
-  // block.
-
-  // The summary of the traversal algorithm:
-  //
-  // R is live-in in B, if there exists a U(R), such that rdef(R) dom B
-  // and (U \in IDF(B) or B dom U).
-  //
-  // for (C : children) {
-  //   LU = {}
-  //   traverse(C, LU)
-  //   LiveUses += LU
-  // }
-  //
-  // LiveUses -= Defs(B);
-  // LiveUses += UpwardExposedUses(B);
-  // for (C : IIDF[B])
-  //   for (U : LiveUses)
-  //     if (Rdef(U) dom C)
-  //       C.addLiveIn(U)
-  //
-
-  // Go up the dominator tree (depth-first).
-  MachineDomTreeNode *N = MDT.getNode(B);
-  for (auto I : *N) {
-    RefMap L;
-    MachineBasicBlock *SB = I->getBlock();
-    traverse(SB, L);
-
-    for (auto S : L)
-      LiveIn[S.first].insert(S.second.begin(), S.second.end());
-  }
-
-  if (Trace) {
-    dbgs() << "\n-- BB#" << B->getNumber() << ": " << __func__
-           << " after recursion into: {";
-    for (auto I : *N)
-      dbgs() << ' ' << I->getBlock()->getNumber();
-    dbgs() << " }\n";
-    dbgs() << "  LiveIn: " << Print<RefMap>(LiveIn, DFG) << '\n';
-    dbgs() << "  Local:  " << Print<RegisterAggr>(LiveMap[B], DFG) << '\n';
-  }
-
-  // Add reaching defs of phi uses that are live on exit from this block.
-  RefMap &PUs = PhiLOX[B];
-  for (auto &S : PUs)
-    LiveIn[S.first].insert(S.second.begin(), S.second.end());
-
-  if (Trace) {
-    dbgs() << "after LOX\n";
-    dbgs() << "  LiveIn: " << Print<RefMap>(LiveIn, DFG) << '\n';
-    dbgs() << "  Local:  " << Print<RegisterAggr>(LiveMap[B], DFG) << '\n';
-  }
-
-  // The LiveIn map at this point has all defs that are live-on-exit from B,
-  // as if they were live-on-entry to B. First, we need to filter out all
-  // defs that are present in this block. Then we will add reaching defs of
-  // all upward-exposed uses.
-
-  // To filter out the defs, first make a copy of LiveIn, and then re-populate
-  // LiveIn with the defs that should remain.
-  RefMap LiveInCopy = LiveIn;
-  LiveIn.clear();
-
-  for (const std::pair<RegisterId,NodeRefSet> &LE : LiveInCopy) {
-    RegisterRef LRef(LE.first);
-    NodeRefSet &NewDefs = LiveIn[LRef.Reg]; // To be filled.
-    const NodeRefSet &OldDefs = LE.second;
-    for (NodeRef OR : OldDefs) {
-      // R is a def node that was live-on-exit
-      auto DA = DFG.addr<DefNode*>(OR.first);
-      NodeAddr<InstrNode*> IA = DA.Addr->getOwner(DFG);
-      NodeAddr<BlockNode*> BA = IA.Addr->getOwner(DFG);
-      if (B != BA.Addr->getCode()) {
-        // Defs from a different block need to be preserved. Defs from this
-        // block will need to be processed further, except for phi defs, the
-        // liveness of which is handled through the PhiLON/PhiLOX maps.
-        NewDefs.insert(OR);
-        continue;
-      }
-
-      // Defs from this block need to stop the liveness from being
-      // propagated upwards. This only applies to non-preserving defs,
-      // and to the parts of the register actually covered by those defs.
-      // (Note that phi defs should always be preserving.)
-      RegisterAggr RRs(PRI);
-      LRef.Mask = OR.second;
-
-      if (!DFG.IsPreservingDef(DA)) {
-        assert(!(IA.Addr->getFlags() & NodeAttrs::Phi));
-        // DA is a non-phi def that is live-on-exit from this block, and
-        // that is also located in this block. LRef is a register ref
-        // whose use this def reaches. If DA covers LRef, then no part
-        // of LRef is exposed upwards.A
-        if (RRs.insert(DA.Addr->getRegRef(DFG)).hasCoverOf(LRef))
-          continue;
-      }
-
-      // DA itself was not sufficient to cover LRef. In general, it is
-      // the last in a chain of aliased defs before the exit from this block.
-      // There could be other defs in this block that are a part of that
-      // chain. Check that now: accumulate the registers from these defs,
-      // and if they all together cover LRef, it is not live-on-entry.
-      for (NodeAddr<DefNode*> TA : getAllReachingDefs(DA)) {
-        // DefNode -> InstrNode -> BlockNode.
-        NodeAddr<InstrNode*> ITA = TA.Addr->getOwner(DFG);
-        NodeAddr<BlockNode*> BTA = ITA.Addr->getOwner(DFG);
-        // Reaching defs are ordered in the upward direction.
-        if (BTA.Addr->getCode() != B) {
-          // We have reached past the beginning of B, and the accumulated
-          // registers are not covering LRef. The first def from the
-          // upward chain will be live.
-          // Subtract all accumulated defs (RRs) from LRef.
-          RegisterRef T = RRs.clearIn(LRef);
-          assert(T);
-          NewDefs.insert({TA.Id,T.Mask});
-          break;
-        }
-
-        // TA is in B. Only add this def to the accumulated cover if it is
-        // not preserving.
-        if (!(TA.Addr->getFlags() & NodeAttrs::Preserving))
-          RRs.insert(TA.Addr->getRegRef(DFG));
-        // If this is enough to cover LRef, then stop.
-        if (RRs.hasCoverOf(LRef))
-          break;
-      }
-    }
-  }
-
-  emptify(LiveIn);
-
-  if (Trace) {
-    dbgs() << "after defs in block\n";
-    dbgs() << "  LiveIn: " << Print<RefMap>(LiveIn, DFG) << '\n';
-    dbgs() << "  Local:  " << Print<RegisterAggr>(LiveMap[B], DFG) << '\n';
-  }
-
-  // Scan the block for upward-exposed uses and add them to the tracking set.
-  for (auto I : DFG.getFunc().Addr->findBlock(B, DFG).Addr->members(DFG)) {
-    NodeAddr<InstrNode*> IA = I;
-    if (IA.Addr->getKind() != NodeAttrs::Stmt)
-      continue;
-    for (NodeAddr<UseNode*> UA : IA.Addr->members_if(DFG.IsUse, DFG)) {
-      if (UA.Addr->getFlags() & NodeAttrs::Undef)
-        continue;
-      RegisterRef RR = PRI.normalize(UA.Addr->getRegRef(DFG));
-      for (NodeAddr<DefNode*> D : getAllReachingDefs(UA))
-        if (getBlockWithRef(D.Id) != B)
-          LiveIn[RR.Reg].insert({D.Id,RR.Mask});
-    }
-  }
-
-  if (Trace) {
-    dbgs() << "after uses in block\n";
-    dbgs() << "  LiveIn: " << Print<RefMap>(LiveIn, DFG) << '\n';
-    dbgs() << "  Local:  " << Print<RegisterAggr>(LiveMap[B], DFG) << '\n';
-  }
-
-  // Phi uses should not be propagated up the dominator tree, since they
-  // are not dominated by their corresponding reaching defs.
-  RegisterAggr &Local = LiveMap[B];
-  RefMap &LON = PhiLON[B];
-  for (auto &R : LON) {
-    LaneBitmask M;
-    for (auto P : R.second)
-      M |= P.second;
-    Local.insert(RegisterRef(R.first,M));
-  }
-
-  if (Trace) {
-    dbgs() << "after phi uses in block\n";
-    dbgs() << "  LiveIn: " << Print<RefMap>(LiveIn, DFG) << '\n';
-    dbgs() << "  Local:  " << Print<RegisterAggr>(Local, DFG) << '\n';
-  }
-
-  for (auto C : IIDF[B]) {
-    RegisterAggr &LiveC = LiveMap[C];
-    for (const std::pair<RegisterId,NodeRefSet> &S : LiveIn)
-      for (auto R : S.second)
-        if (MDT.properlyDominates(getBlockWithRef(R.first), C))
-          LiveC.insert(RegisterRef(S.first, R.second));
-  }
-}
-
-
-void Liveness::emptify(RefMap &M) {
-  for (auto I = M.begin(), E = M.end(); I != E; )
-    I = I->second.empty() ? M.erase(I) : std::next(I);
-}
-

lib/Target/Hexagon/RDFRegisters.h

-//===--- RDFRegisters.h -----------------------------------------*- C++ -*-===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_LIB_TARGET_HEXAGON_RDFREGISTERS_H
-#define LLVM_LIB_TARGET_HEXAGON_RDFREGISTERS_H
-
-#include "llvm/ADT/BitVector.h"
-#include "llvm/Target/TargetRegisterInfo.h"
-
-#include <set>
-#include <unordered_map>
-#include <vector>
-
-namespace llvm {
-namespace rdf {
-
-  typedef uint32_t RegisterId;
-
-  // Template class for a map translating uint32_t into arbitrary types.
-  // The map will act like an indexed set: upon insertion of a new object,
-  // it will automatically assign a new index to it. Index of 0 is treated
-  // as invalid and is never allocated.
-  template <typename T, unsigned N = 32>
-  struct IndexedSet {
-    IndexedSet() : Map() { Map.reserve(N); }
-
-    T get(uint32_t Idx) const {
-      // Index Idx corresponds to Map[Idx-1].
-      assert(Idx != 0 && !Map.empty() && Idx-1 < Map.size());
-      return Map[Idx-1];
-    }
-
-    uint32_t insert(T Val) {
-      // Linear search.
-      auto F = llvm::find(Map, Val);
-      if (F != Map.end())
-        return F - Map.begin() + 1;
-      Map.push_back(Val);
-      return Map.size();  // Return actual_index + 1.
-    }
-
-    uint32_t find(T Val) const {
-      auto F = llvm::find(Map, Val);
-      assert(F != Map.end());
-      return F - Map.begin() + 1;
-    }
-
-    typedef typename std::vector<T>::const_iterator const_iterator;
-    const_iterator begin() const { return Map.begin(); }
-    const_iterator end() const { return Map.end(); }
-
-  private:
-    std::vector<T> Map;
-  };
-
-  struct RegisterRef {
-    RegisterId Reg = 0;
-    LaneBitmask Mask = LaneBitmask::getNone();
-
-    RegisterRef() = default;
-    explicit RegisterRef(RegisterId R, LaneBitmask M = LaneBitmask::getAll())
-      : Reg(R), Mask(R != 0 ? M : LaneBitmask::getNone()) {}
-
-    operator bool() const {
-      return Reg != 0 && Mask.any();
-    }
-    bool operator== (const RegisterRef &RR) const {
-      return Reg == RR.Reg && Mask == RR.Mask;
-    }
-    bool operator!= (const RegisterRef &RR) const {
-      return !operator==(RR);
-    }
-    bool operator< (const RegisterRef &RR) const {
-      return Reg < RR.Reg || (Reg == RR.Reg && Mask < RR.Mask);
-    }
-  };
-
-
-  struct PhysicalRegisterInfo {
-    PhysicalRegisterInfo(const TargetRegisterInfo &tri,
-                         const MachineFunction &mf);
-
-    static bool isRegMaskId(RegisterId R) {
-      return TargetRegisterInfo::isStackSlot(R);
-    }
-    RegisterId getRegMaskId(const uint32_t *RM) const {
-      return TargetRegisterInfo::index2StackSlot(RegMasks.find(RM));
-    }
-    const uint32_t *getRegMaskBits(RegisterId R) const {
-      return RegMasks.get(TargetRegisterInfo::stackSlot2Index(R));
-    }
-    RegisterRef normalize(RegisterRef RR) const;
-
-    bool alias(RegisterRef RA, RegisterRef RB) const {
-      if (!isRegMaskId(RA.Reg))
-        return !isRegMaskId(RB.Reg) ? aliasRR(RA, RB) : aliasRM(RA, RB);
-      return !isRegMaskId(RB.Reg) ? aliasRM(RB, RA) : aliasMM(RA, RB);
-    }
-    std::set<RegisterId> getAliasSet(RegisterId Reg) const;
-
-    RegisterRef getRefForUnit(uint32_t U) const {
-      return RegisterRef(UnitInfos[U].Reg, UnitInfos[U].Mask);
-    }
-
-    const TargetRegisterInfo &getTRI() const { return TRI; }
-
-  private:
-    struct RegInfo {
-      const TargetRegisterClass *RegClass = nullptr;
-    };
-    struct UnitInfo {
-      RegisterId Reg = 0;
-      LaneBitmask Mask;
-    };
-
-    const TargetRegisterInfo &TRI;
-    std::vector<RegInfo> RegInfos;
-    std::vector<UnitInfo> UnitInfos;
-    IndexedSet<const uint32_t*> RegMasks;
-
-    bool aliasRR(RegisterRef RA, RegisterRef RB) const;
-    bool aliasRM(RegisterRef RR, RegisterRef RM) const;
-    bool aliasMM(RegisterRef RM, RegisterRef RN) const;
-  };
-
-
-  struct RegisterAggr {
-    RegisterAggr(const PhysicalRegisterInfo &pri)
-        : Units(pri.getTRI().getNumRegUnits()), PRI(pri) {}
-    RegisterAggr(const RegisterAggr &RG) = default;
-
-    bool empty() const { return Units.empty(); }
-    bool hasAliasOf(RegisterRef RR) const;
-    bool hasCoverOf(RegisterRef RR) const;
-    static bool isCoverOf(RegisterRef RA, RegisterRef RB,
-                          const PhysicalRegisterInfo &PRI) {
-      return RegisterAggr(PRI).insert(RA).hasCoverOf(RB);
-    }
-
-    RegisterAggr &insert(RegisterRef RR);
-    RegisterAggr &insert(const RegisterAggr &RG);
-    RegisterAggr &intersect(RegisterRef RR);
-    RegisterAggr &intersect(const RegisterAggr &RG);
-    RegisterAggr &clear(RegisterRef RR);
-    RegisterAggr &clear(const RegisterAggr &RG);
-
-    RegisterRef intersectWith(RegisterRef RR) const;
-    RegisterRef clearIn(RegisterRef RR) const;
-    RegisterRef makeRegRef() const;
-
-    void print(raw_ostream &OS) const;
-
-    struct rr_iterator {
-      typedef std::map<RegisterId,LaneBitmask> MapType;
-    private:
-      MapType Masks;
-      MapType::iterator Pos;
-      unsigned Index;
-      const RegisterAggr *Owner;
-    public:
-      rr_iterator(const RegisterAggr &RG, bool End);
-      RegisterRef operator*() const {
-        return RegisterRef(Pos->first, Pos->second);
-      }
-      rr_iterator &operator++() {
-        ++Pos;
-        ++Index;
-        return *this;
-      }
-      bool operator==(const rr_iterator &I) const {
-        assert(Owner == I.Owner);
-        return Index == I.Index;
-      }
-      bool operator!=(const rr_iterator &I) const {
-        return !(*this == I);
-      }
-    };
-
-    rr_iterator rr_begin() const {
-      return rr_iterator(*this, false);
-    }
-    rr_iterator rr_end() const {
-      return rr_iterator(*this, true);
-    }
-
-  private:
-    BitVector Units;
-    const PhysicalRegisterInfo &PRI;
-  };
-
-
-  // Optionally print the lane mask, if it is not ~0.
-  struct PrintLaneMaskOpt {
-    PrintLaneMaskOpt(LaneBitmask M) : Mask(M) {}
-    LaneBitmask Mask;
-  };
-  raw_ostream &operator<< (raw_ostream &OS, const PrintLaneMaskOpt &P);
-
-} // namespace rdf
-} // namespace llvm
-
-#endif
-

lib/Target/Hexagon/RDFRegisters.cpp

-//===--- RDFRegisters.cpp ---------------------------------------*- C++ -*-===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#include "RDFRegisters.h"
-#include "llvm/ADT/BitVector.h"
-#include "llvm/CodeGen/MachineFunction.h"
-
-using namespace llvm;
-using namespace rdf;
-
-PhysicalRegisterInfo::PhysicalRegisterInfo(const TargetRegisterInfo &tri,
-      const MachineFunction &mf)
-    : TRI(tri) {
-  RegInfos.resize(TRI.getNumRegs());
-
-  BitVector BadRC(TRI.getNumRegs());
-  for (const TargetRegisterClass *RC : TRI.regclasses()) {
-    for (MCPhysReg R : *RC) {
-      RegInfo &RI = RegInfos[R];
-      if (RI.RegClass != nullptr && !BadRC[R]) {
-        if (RC->LaneMask != RI.RegClass->LaneMask) {
-          BadRC.set(R);
-          RI.RegClass = nullptr;
-        }
-      } else
-        RI.RegClass = RC;
-    }
-  }
-
-  UnitInfos.resize(TRI.getNumRegUnits());
-
-  for (uint32_t U = 0, NU = TRI.getNumRegUnits(); U != NU; ++U) {
-    if (UnitInfos[U].Reg != 0)
-      continue;
-    MCRegUnitRootIterator R(U, &TRI);
-    assert(R.isValid());
-    RegisterId F = *R;
-    ++R;
-    if (R.isValid()) {
-      UnitInfos[U].Mask = LaneBitmask::getAll();
-      UnitInfos[U].Reg = F;
-    } else {
-      for (MCRegUnitMaskIterator I(F, &TRI); I.isValid(); ++I) {
-        std::pair<uint32_t,LaneBitmask> P = *I;
-        UnitInfo &UI = UnitInfos[P.first];
-        UI.Reg = F;
-        if (P.second.any()) {
-          UI.Mask = P.second;
-        } else {
-          if (const TargetRegisterClass *RC = RegInfos[F].RegClass)
-            UI.Mask = RC->LaneMask;
-          else
-            UI.Mask = LaneBitmask::getAll();
-        }
-      }
-    }
-  }
-
-  for (const uint32_t *RM : TRI.getRegMasks())
-    RegMasks.insert(RM);
-  for (const MachineBasicBlock &B : mf)
-    for (const MachineInstr &In : B)
-      for (const MachineOperand &Op : In.operands())
-        if (Op.isRegMask())
-          RegMasks.insert(Op.getRegMask());
-}
-
-RegisterRef PhysicalRegisterInfo::normalize(RegisterRef RR) const {
-  return RR;
-}
-
-std::set<RegisterId> PhysicalRegisterInfo::getAliasSet(RegisterId Reg) const {
-  // Do not include RR in the alias set.
-  std::set<RegisterId> AS;
-  assert(isRegMaskId(Reg) || TargetRegisterInfo::isPhysicalRegister(Reg));
-  if (isRegMaskId(Reg)) {
-    // XXX SLOW
-    const uint32_t *MB = getRegMaskBits(Reg);
-    for (unsigned i = 1, e = TRI.getNumRegs(); i != e; ++i) {
-      if (MB[i/32] & (1u << (i%32)))
-        continue;
-      AS.insert(i);
-    }
-    for (const uint32_t *RM : RegMasks) {
-      RegisterId MI = getRegMaskId(RM);
-      if (MI != Reg && aliasMM(RegisterRef(Reg), RegisterRef(MI)))
-        AS.insert(MI);
-    }
-    return AS;
-  }
-
-  for (MCRegAliasIterator AI(Reg, &TRI, false); AI.isValid(); ++AI)
-    AS.insert(*AI);
-  for (const uint32_t *RM : RegMasks) {
-    RegisterId MI = getRegMaskId(RM);
-    if (aliasRM(RegisterRef(Reg), RegisterRef(MI)))
-      AS.insert(MI);
-  }
-  return AS;
-}
-
-bool PhysicalRegisterInfo::aliasRR(RegisterRef RA, RegisterRef RB) const {
-  assert(TargetRegisterInfo::isPhysicalRegister(RA.Reg));
-  assert(TargetRegisterInfo::isPhysicalRegister(RB.Reg));
-
-  MCRegUnitMaskIterator UMA(RA.Reg, &TRI);
-  MCRegUnitMaskIterator UMB(RB.Reg, &TRI);
-  // Reg units are returned in the numerical order.
-  while (UMA.isValid() && UMB.isValid()) {
-    // Skip units that are masked off in RA.
-    std::pair<RegisterId,LaneBitmask> PA = *UMA;
-    if (PA.second.any() && (PA.second & RA.Mask).none()) {
-      ++UMA;
-      continue;
-    }
-    // Skip units that are masked off in RB.
-    std::pair<RegisterId,LaneBitmask> PB = *UMB;
-    if (PB.second.any() && (PB.second & RB.Mask).none()) {
-      ++UMB;
-      continue;
-    }
-
-    if (PA.first == PB.first)
-      return true;
-    if (PA.first < PB.first)
-      ++UMA;
-    else if (PB.first < PA.first)
-      ++UMB;
-  }
-  return false;
-}
-
-bool PhysicalRegisterInfo::aliasRM(RegisterRef RR, RegisterRef RM) const {
-  assert(TargetRegisterInfo::isPhysicalRegister(RR.Reg) && isRegMaskId(RM.Reg));
-  const uint32_t *MB = getRegMaskBits(RM.Reg);
-  bool Preserved = MB[RR.Reg/32] & (1u << (RR.Reg%32));
-  // If the lane mask information is "full", e.g. when the given lane mask
-  // is a superset of the lane mask from the register class, check the regmask
-  // bit directly.
-  if (RR.Mask == LaneBitmask::getAll())
-    return !Preserved;
-  const TargetRegisterClass *RC = RegInfos[RR.Reg].RegClass;
-  if (RC != nullptr && (RR.Mask & RC->LaneMask) == RC->LaneMask)
-    return !Preserved;
-
-  // Otherwise, check all subregisters whose lane mask overlaps the given
-  // mask. For each such register, if it is preserved by the regmask, then
-  // clear the corresponding bits in the given mask. If at the end, all
-  // bits have been cleared, the register does not alias the regmask (i.e.
-  // is it preserved by it).
-  LaneBitmask M = RR.Mask;
-  for (MCSubRegIndexIterator SI(RR.Reg, &TRI); SI.isValid(); ++SI) {
-    LaneBitmask SM = TRI.getSubRegIndexLaneMask(SI.getSubRegIndex());
-    if ((SM & RR.Mask).none())
-      continue;
-    unsigned SR = SI.getSubReg();
-    if (!(MB[SR/32] & (1u << (SR%32))))
-      continue;
-    // The subregister SR is preserved.
-    M &= ~SM;
-    if (M.none())
-      return false;
-  }
-
-  return true;
-}
-
-bool PhysicalRegisterInfo::aliasMM(RegisterRef RM, RegisterRef RN) const {
-  assert(isRegMaskId(RM.Reg) && isRegMaskId(RN.Reg));
-  unsigned NumRegs = TRI.getNumRegs();
-  const uint32_t *BM = getRegMaskBits(RM.Reg);
-  const uint32_t *BN = getRegMaskBits(RN.Reg);
-
-  for (unsigned w = 0, nw = NumRegs/32; w != nw; ++w) {
-    // Intersect the negations of both words. Disregard reg=0,
-    // i.e. 0th bit in the 0th word.
-    uint32_t C = ~BM[w] & ~BN[w];
-    if (w == 0)
-      C &= ~1;
-    if (C)
-      return true;
-  }
-
-  // Check the remaining registers in the last word.
-  unsigned TailRegs = NumRegs % 32;
-  if (TailRegs == 0)
-    return false;
-  unsigned TW = NumRegs / 32;
-  uint32_t TailMask = (1u << TailRegs) - 1;
-  if (~BM[TW] & ~BN[TW] & TailMask)
-    return true;
-
-  return false;
-}
-
-
-bool RegisterAggr::hasAliasOf(RegisterRef RR) const {
-  if (PhysicalRegisterInfo::isRegMaskId(RR.Reg)) {
-    // XXX SLOW
-    const uint32_t *MB = PRI.getRegMaskBits(RR.Reg);
-    for (unsigned i = 1, e = PRI.getTRI().getNumRegs(); i != e; ++i) {
-      if (MB[i/32] & (1u << (i%32)))
-        continue;
-      if (hasAliasOf(RegisterRef(i, LaneBitmask::getAll())))
-        return true;
-    }
-    return false;
-  }
-
-  for (MCRegUnitMaskIterator U(RR.Reg, &PRI.getTRI()); U.isValid(); ++U) {
-    std::pair<uint32_t,LaneBitmask> P = *U;
-    if (P.second.none() || (P.second & RR.Mask).any())
-      if (Units.test(P.first))
-        return true;
-  }
-  return false;
-}
-
-bool RegisterAggr::hasCoverOf(RegisterRef RR) const {
-  if (PhysicalRegisterInfo::isRegMaskId(RR.Reg)) {
-    // XXX SLOW
-    const uint32_t *MB = PRI.getRegMaskBits(RR.Reg);
-    for (unsigned i = 1, e = PRI.getTRI().getNumRegs(); i != e; ++i) {
-      if (MB[i/32] & (1u << (i%32)))
-        continue;
-      if (!hasCoverOf(RegisterRef(i, LaneBitmask::getAll())))
-        return false;
-    }
-    return true;
-  }
-
-  for (MCRegUnitMaskIterator U(RR.Reg, &PRI.getTRI()); U.isValid(); ++U) {
-    std::pair<uint32_t,LaneBitmask> P = *U;
-    if (P.second.none() || (P.second & RR.Mask).any())
-      if (!Units.test(P.first))
-        return false;
-  }
-  return true;
-}
-
-RegisterAggr &RegisterAggr::insert(RegisterRef RR) {
-  if (PhysicalRegisterInfo::isRegMaskId(RR.Reg)) {
-    BitVector PU(PRI.getTRI().getNumRegUnits()); // Preserved units.
-    const uint32_t *MB = PRI.getRegMaskBits(RR.Reg);
-    for (unsigned i = 1, e = PRI.getTRI().getNumRegs(); i != e; ++i) {
-      if (!(MB[i/32] & (1u << (i%32))))
-        continue;
-      for (MCRegUnitIterator U(i, &PRI.getTRI()); U.isValid(); ++U)
-        PU.set(*U);
-    }
-    Units |= PU.flip();
-    return *this;
-  }
-
-  for (MCRegUnitMaskIterator U(RR.Reg, &PRI.getTRI()); U.isValid(); ++U) {
-    std::pair<uint32_t,LaneBitmask> P = *U;
-    if (P.second.none() || (P.second & RR.Mask).any())
-      Units.set(P.first);
-  }
-  return *this;
-}
-
-RegisterAggr &RegisterAggr::insert(const RegisterAggr &RG) {
-  Units |= RG.Units;
-  return *this;
-}
-
-RegisterAggr &RegisterAggr::intersect(RegisterRef RR) {
-  return intersect(RegisterAggr(PRI).insert(RR));
-}
-
-RegisterAggr &RegisterAggr::intersect(const RegisterAggr &RG) {
-  Units &= RG.Units;
-  return *this;
-}
-
-RegisterAggr &RegisterAggr::clear(RegisterRef RR) {
-  return clear(RegisterAggr(PRI).insert(RR));
-}
-
-RegisterAggr &RegisterAggr::clear(const RegisterAggr &RG) {
-  Units.reset(RG.Units);
-  return *this;
-}
-
-RegisterRef RegisterAggr::intersectWith(RegisterRef RR) const {
-  RegisterAggr T(PRI);
-  T.insert(RR).intersect(*this);
-  if (T.empty())
-    return RegisterRef();
-  RegisterRef NR = T.makeRegRef();
-  assert(NR);
-  return NR;
-}
-
-RegisterRef RegisterAggr::clearIn(RegisterRef RR) const {
-  return RegisterAggr(PRI).insert(RR).clear(*this).makeRegRef();
-}
-
-RegisterRef RegisterAggr::makeRegRef() const {
-  int U = Units.find_first();
-  if (U < 0)
-    return RegisterRef();
-
-  auto AliasedRegs = [this] (uint32_t Unit, BitVector &Regs) {
-    for (MCRegUnitRootIterator R(Unit, &PRI.getTRI()); R.isValid(); ++R)
-      for (MCSuperRegIterator S(*R, &PRI.getTRI(), true); S.isValid(); ++S)
-        Regs.set(*S);
-  };
-
-  // Find the set of all registers that are aliased to all the units
-  // in this aggregate.
-
-  // Get all the registers aliased to the first unit in the bit vector.
-  BitVector Regs(PRI.getTRI().getNumRegs());
-  AliasedRegs(U, Regs);
-  U = Units.find_next(U);
-
-  // For each other unit, intersect it with the set of all registers
-  // aliased that unit.
-  while (U >= 0) {
-    BitVector AR(PRI.getTRI().getNumRegs());
-    AliasedRegs(U, AR);
-    Regs &= AR;
-    U = Units.find_next(U);
-  }
-
-  // If there is at least one register remaining, pick the first one,
-  // and consolidate the masks of all of its units contained in this
-  // aggregate.
-
-  int F = Regs.find_first();
-  if (F <= 0)
-    return RegisterRef();
-
-  LaneBitmask M;
-  for (MCRegUnitMaskIterator I(F, &PRI.getTRI()); I.isValid(); ++I) {
-    std::pair<uint32_t,LaneBitmask> P = *I;
-    if (Units.test(P.first))
-      M |= P.second.none() ? LaneBitmask::getAll() : P.second;
-  }
-  return RegisterRef(F, M);
-}
-
-void RegisterAggr::print(raw_ostream &OS) const {
-  OS << '{';
-  for (int U = Units.find_first(); U >= 0; U = Units.find_next(U))
-    OS << ' ' << PrintRegUnit(U, &PRI.getTRI());
-  OS << " }";
-}
-
-RegisterAggr::rr_iterator::rr_iterator(const RegisterAggr &RG,
-      bool End)
-    : Owner(&RG) {
-  for (int U = RG.Units.find_first(); U >= 0; U = RG.Units.find_next(U)) {
-    RegisterRef R = RG.PRI.getRefForUnit(U);
-    Masks[R.Reg] |= R.Mask;
-  }
-  Pos = End ? Masks.end() : Masks.begin();
-  Index = End ? Masks.size() : 0;
-}
-