[SparsePropagation] Move member definitions to header (NFC)

[mssimpso]

Summary

After rL314734, AbstractLatticeFunction and SparseSolver are class templates parameterized by a lattice value. In order to use the member functions, we need to move them into the header.

[• dberlin]

LGTM

[davide]

thanks

include/llvm/Analysis/SparsePropagation.h

 // This file implements an abstract sparse conditional propagation algorithm,
 // modeled after SCCP, but with a customizable lattice function.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_ANALYSIS_SPARSEPROPAGATION_H
 #define LLVM_ANALYSIS_SPARSEPROPAGATION_H
 
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/Support/Debug.h"
 #include <set>
-#include <utility>
-#include <vector>
+
+#define DEBUG_TYPE "sparseprop"
 
 namespace llvm {
 
-class Argument;
-class BasicBlock;
-class Constant;
-class Function;
-class Instruction;
-class PHINode;
-class raw_ostream;
 template <class LatticeVal> class SparseSolver;
-class TerminatorInst;
-class Value;
-template <typename T> class SmallVectorImpl;
 
 /// AbstractLatticeFunction - This class is implemented by the dataflow instance
 /// to specify what the lattice values are and how they handle merges etc.  This
 /// gives the client the power to compute lattice values from instructions,
 /// constants, etc.  The current requirement is that lattice values must be
 /// copyable.  At the moment, nothing tries to avoid copying.
-
-
 template <class LatticeVal> class AbstractLatticeFunction {
 private:
   LatticeVal UndefVal, OverdefinedVal, UntrackedVal;
 
 public:
   AbstractLatticeFunction(LatticeVal undefVal, LatticeVal overdefinedVal,
                           LatticeVal untrackedVal) {
     UndefVal = undefVal;
     OverdefinedVal = overdefinedVal;
     UntrackedVal = untrackedVal;
   }
 
-  virtual ~AbstractLatticeFunction();
+  virtual ~AbstractLatticeFunction() = default;
 
   LatticeVal getUndefVal()       const { return UndefVal; }
   LatticeVal getOverdefinedVal() const { return OverdefinedVal; }
   LatticeVal getUntrackedVal()   const { return UntrackedVal; }
 
   /// IsUntrackedValue - If the specified Value is something that is obviously
   /// uninteresting to the analysis (and would always return UntrackedVal),
   /// this function can return true to avoid pointless work.
public:
   /// ComputeInstructionState - Given an instruction and a vector of its operand
   /// values, compute the result value of the instruction.
   virtual LatticeVal ComputeInstructionState(Instruction &I,
                                              SparseSolver<LatticeVal> &SS) {
     return getOverdefinedVal(); // always safe, never useful.
   }
 
   /// PrintValue - Render the specified lattice value to the specified stream.
-  virtual void PrintValue(LatticeVal V, raw_ostream &OS);
+  virtual void PrintValue(LatticeVal V, raw_ostream &OS) {
+    if (V == UndefVal)
+      OS << "undefined";
+    else if (V == OverdefinedVal)
+      OS << "overdefined";
+    else if (V == UntrackedVal)
+      OS << "untracked";
+    else
+      OS << "unknown lattice value";
+  }
 };
 
 /// SparseSolver - This class is a general purpose solver for Sparse Conditional
 /// Propagation with a programmable lattice function.
 template <class LatticeVal> class SparseSolver {
 
   /// LatticeFunc - This is the object that knows the lattice and how to do
   /// compute transfer functions.
template <class LatticeVal> class SparseSolver {
   using Edge = std::pair<BasicBlock *, BasicBlock *>;
   std::set<Edge> KnownFeasibleEdges;
 
 public:
   explicit SparseSolver(AbstractLatticeFunction<LatticeVal> *Lattice)
       : LatticeFunc(Lattice) {}
   SparseSolver(const SparseSolver &) = delete;
   SparseSolver &operator=(const SparseSolver &) = delete;
-  ~SparseSolver() { delete LatticeFunc; }
 
   /// Solve - Solve for constants and executable blocks.
-  void Solve(Function &F);
+  void Solve(Function &F) {
+    MarkBlockExecutable(&F.getEntryBlock());
+
+    // Process the work lists until they are empty!
+    while (!BBWorkList.empty() || !InstWorkList.empty()) {
+      // Process the instruction work list.
+      while (!InstWorkList.empty()) {
+        Instruction *I = InstWorkList.back();
+        InstWorkList.pop_back();
+
+        DEBUG(dbgs() << "\nPopped off I-WL: " << *I << "\n");
+
+        // "I" got into the work list because it made a transition. See if any
+        // users are both live and in need of updating.
+        for (User *U : I->users()) {
+          Instruction *UI = cast<Instruction>(U);
+          if (BBExecutable.count(UI->getParent())) // Inst is executable?
+            visitInst(*UI);
+        }
+      }
 
-  void Print(Function &F, raw_ostream &OS) const;
+      // Process the basic block work list.
+      while (!BBWorkList.empty()) {
+        BasicBlock *BB = BBWorkList.back();
+        BBWorkList.pop_back();
+
+        DEBUG(dbgs() << "\nPopped off BBWL: " << *BB);
+
+        // Notify all instructions in this basic block that they are newly
+        // executable.
+        for (Instruction &I : *BB)
+          visitInst(I);
+      }
+    }
+  }
+
+  void Print(Function &F, raw_ostream &OS) const {
+    OS << "\nFUNCTION: " << F.getName() << "\n";
+    for (auto &BB : F) {
+      if (!BBExecutable.count(&BB))
+        OS << "INFEASIBLE: ";
+      OS << "\t";
+      if (BB.hasName())
+        OS << BB.getName() << ":\n";
+      else
+        OS << "; anon bb\n";
+      for (auto &I : BB) {
+        LatticeFunc->PrintValue(getLatticeState(&I), OS);
+        OS << I << "\n";
+      }
+
+      OS << "\n";
+    }
+  }
 
   /// getLatticeState - Return the LatticeVal object that corresponds to the
   /// value.  If an value is not in the map, it is returned as untracked,
   /// unlike the getValueState method.
   LatticeVal getLatticeState(Value *V) const {
     auto I = ValueState.find(V);
     return I != ValueState.end() ? I->second : LatticeFunc->getUntrackedVal();
   }
 
   /// getValueState - Return the LatticeVal object that corresponds to the
   /// value, initializing the value's state if it hasn't been entered into the
   /// map yet.   This function is necessary because not all values should start
   /// out in the underdefined state... Arguments should be overdefined, and
   /// constants should be marked as constants.
-  LatticeVal getValueState(Value *V);
+  LatticeVal getValueState(Value *V) {
+    auto I = ValueState.find(V);
+    if (I != ValueState.end())
+      return I->second; // Common case, in the map
+
+    LatticeVal LV;
+    if (LatticeFunc->IsUntrackedValue(V))
+      return LatticeFunc->getUntrackedVal();
+    else if (Constant *C = dyn_cast<Constant>(V))
+      LV = LatticeFunc->ComputeConstant(C);
+    else if (Argument *A = dyn_cast<Argument>(V))
+      LV = LatticeFunc->ComputeArgument(A);
+    else if (!isa<Instruction>(V))
+      // All other non-instructions are overdefined.
+      LV = LatticeFunc->getOverdefinedVal();
+    else
+      // All instructions are underdefined by default.
+      LV = LatticeFunc->getUndefVal();
+
+    // If this value is untracked, don't add it to the map.
+    if (LV == LatticeFunc->getUntrackedVal())
+      return LV;
+    return ValueState[V] = LV;
+  }
 
   /// isEdgeFeasible - Return true if the control flow edge from the 'From'
   /// basic block to the 'To' basic block is currently feasible.  If
   /// AggressiveUndef is true, then this treats values with unknown lattice
   /// values as undefined.  This is generally only useful when solving the
   /// lattice, not when querying it.
   bool isEdgeFeasible(BasicBlock *From, BasicBlock *To,
-                      bool AggressiveUndef = false);
+                      bool AggressiveUndef = false) {
+    SmallVector<bool, 16> SuccFeasible;
+    TerminatorInst *TI = From->getTerminator();
+    getFeasibleSuccessors(*TI, SuccFeasible, AggressiveUndef);
+
+    for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
+      if (TI->getSuccessor(i) == To && SuccFeasible[i])
+        return true;
+
+    return false;
+  }
 
   /// isBlockExecutable - Return true if there are any known feasible
   /// edges into the basic block.  This is generally only useful when
   /// querying the lattice.
   bool isBlockExecutable(BasicBlock *BB) const {
     return BBExecutable.count(BB);
   }
 
 private:
   /// UpdateState - When the state for some instruction is potentially updated,
   /// this function notices and adds I to the worklist if needed.
-  void UpdateState(Instruction &Inst, LatticeVal V);
+  void UpdateState(Instruction &Inst, LatticeVal V) {
+    auto I = ValueState.find(&Inst);
+    if (I != ValueState.end() && I->second == V)
+      return; // No change.
+
+    // An update.  Visit uses of I.
+    ValueState[&Inst] = V;
+    InstWorkList.push_back(&Inst);
+  }
 
   /// MarkBlockExecutable - This method can be used by clients to mark all of
   /// the blocks that are known to be intrinsically live in the processed unit.
-  void MarkBlockExecutable(BasicBlock *BB);
+  void MarkBlockExecutable(BasicBlock *BB) {
+    DEBUG(dbgs() << "Marking Block Executable: " << BB->getName() << "\n");
+    BBExecutable.insert(BB);  // Basic block is executable!
+    BBWorkList.push_back(BB); // Add the block to the work list!
+  }
 
   /// markEdgeExecutable - Mark a basic block as executable, adding it to the BB
   /// work list if it is not already executable.
-  void markEdgeExecutable(BasicBlock *Source, BasicBlock *Dest);
+  void markEdgeExecutable(BasicBlock *Source, BasicBlock *Dest) {
+    if (!KnownFeasibleEdges.insert(Edge(Source, Dest)).second)
+      return; // This edge is already known to be executable!
+
+    DEBUG(dbgs() << "Marking Edge Executable: " << Source->getName() << " -> "
+                 << Dest->getName() << "\n");
+
+    if (BBExecutable.count(Dest)) {
+      // The destination is already executable, but we just made an edge
+      // feasible that wasn't before.  Revisit the PHI nodes in the block
+      // because they have potentially new operands.
+      for (BasicBlock::iterator I = Dest->begin(); isa<PHINode>(I); ++I)
+        visitPHINode(*cast<PHINode>(I));
+    } else {
+      MarkBlockExecutable(Dest);
+    }
+  }
 
   /// getFeasibleSuccessors - Return a vector of booleans to indicate which
   /// successors are reachable from a given terminator instruction.
   void getFeasibleSuccessors(TerminatorInst &TI, SmallVectorImpl<bool> &Succs,
-                             bool AggressiveUndef);
+                             bool AggressiveUndef) {
+    Succs.resize(TI.getNumSuccessors());
+    if (TI.getNumSuccessors() == 0)
+      return;
+
+    if (BranchInst *BI = dyn_cast<BranchInst>(&TI)) {
+      if (BI->isUnconditional()) {
+        Succs[0] = true;
+        return;
+      }
+
+      LatticeVal BCValue;
+      if (AggressiveUndef)
+        BCValue = getValueState(BI->getCondition());
+      else
+        BCValue = getLatticeState(BI->getCondition());
+
+      if (BCValue == LatticeFunc->getOverdefinedVal() ||
+          BCValue == LatticeFunc->getUntrackedVal()) {
+        // Overdefined condition variables can branch either way.
+        Succs[0] = Succs[1] = true;
+        return;
+      }
 
-  void visitInst(Instruction &I);
-  void visitPHINode(PHINode &I);
-  void visitTerminatorInst(TerminatorInst &TI);
+      // If undefined, neither is feasible yet.
+      if (BCValue == LatticeFunc->getUndefVal())
+        return;
+
+      Constant *C =
+          LatticeFunc->GetConstant(BCValue, BI->getCondition(), *this);
+      if (!C || !isa<ConstantInt>(C)) {
+        // Non-constant values can go either way.
+        Succs[0] = Succs[1] = true;
+        return;
+      }
+
+      // Constant condition variables mean the branch can only go a single way
+      Succs[C->isNullValue()] = true;
+      return;
+    }
+
+    if (isa<InvokeInst>(TI)) {
+      // Invoke instructions successors are always executable.
+      // TODO: Could ask the lattice function if the value can throw.
+      Succs[0] = Succs[1] = true;
+      return;
+    }
+
+    if (isa<IndirectBrInst>(TI)) {
+      Succs.assign(Succs.size(), true);
+      return;
+    }
+
+    SwitchInst &SI = cast<SwitchInst>(TI);
+    LatticeVal SCValue;
+    if (AggressiveUndef)
+      SCValue = getValueState(SI.getCondition());
+    else
+      SCValue = getLatticeState(SI.getCondition());
+
+    if (SCValue == LatticeFunc->getOverdefinedVal() ||
+        SCValue == LatticeFunc->getUntrackedVal()) {
+      // All destinations are executable!
+      Succs.assign(TI.getNumSuccessors(), true);
+      return;
+    }
+
+    // If undefined, neither is feasible yet.
+    if (SCValue == LatticeFunc->getUndefVal())
+      return;
+
+    Constant *C = LatticeFunc->GetConstant(SCValue, SI.getCondition(), *this);
+    if (!C || !isa<ConstantInt>(C)) {
+      // All destinations are executable!
+      Succs.assign(TI.getNumSuccessors(), true);
+      return;
+    }
+    SwitchInst::CaseHandle Case = *SI.findCaseValue(cast<ConstantInt>(C));
+    Succs[Case.getSuccessorIndex()] = true;
+  }
+
+  void visitInst(Instruction &I) {
+    // PHIs are handled by the propagation logic, they are never passed into the
+    // transfer functions.
+    if (PHINode *PN = dyn_cast<PHINode>(&I))
+      return visitPHINode(*PN);
+
+    // Otherwise, ask the transfer function what the result is.  If this is
+    // something that we care about, remember it.
+    LatticeVal IV = LatticeFunc->ComputeInstructionState(I, *this);
+    if (IV != LatticeFunc->getUntrackedVal())
+      UpdateState(I, IV);
+
+    if (TerminatorInst *TI = dyn_cast<TerminatorInst>(&I))
+      visitTerminatorInst(*TI);
+  }
+
+  void visitPHINode(PHINode &PN) {
+    // The lattice function may store more information on a PHINode than could
+    // be computed from its incoming values. For example, SSI form stores its
+    // sigma functions as PHINodes with a single incoming value.
+    if (LatticeFunc->IsSpecialCasedPHI(&PN)) {
+      LatticeVal IV = LatticeFunc->ComputeInstructionState(PN, *this);
+      if (IV != LatticeFunc->getUntrackedVal())
+        UpdateState(PN, IV);
+      return;
+    }
+
+    LatticeVal PNIV = getValueState(&PN);
+    LatticeVal Overdefined = LatticeFunc->getOverdefinedVal();
+
+    // If this value is already overdefined (common) just return.
+    if (PNIV == Overdefined || PNIV == LatticeFunc->getUntrackedVal())
+      return; // Quick exit
+
+    // Super-extra-high-degree PHI nodes are unlikely to ever be interesting,
+    // and slow us down a lot.  Just mark them overdefined.
+    if (PN.getNumIncomingValues() > 64) {
+      UpdateState(PN, Overdefined);
+      return;
+    }
+
+    // Look at all of the executable operands of the PHI node. If any of them
+    // are overdefined, the PHI becomes overdefined as well. Otherwise, ask the
+    // transfer function to give us the merge of the incoming values.
+    for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
+      // If the edge is not yet known to be feasible, it doesn't impact the PHI.
+      if (!isEdgeFeasible(PN.getIncomingBlock(i), PN.getParent(), true))
+        continue;
+
+      // Merge in this value.
+      LatticeVal OpVal = getValueState(PN.getIncomingValue(i));
+      if (OpVal != PNIV)
+        PNIV = LatticeFunc->MergeValues(PNIV, OpVal);
+
+      if (PNIV == Overdefined)
+        break; // Rest of input values don't matter.
+    }
+
+    // Update the PHI with the compute value, which is the merge of the inputs.
+    UpdateState(PN, PNIV);
+  }
+
+  void visitTerminatorInst(TerminatorInst &TI) {
+    SmallVector<bool, 16> SuccFeasible;
+    getFeasibleSuccessors(TI, SuccFeasible, true);
+
+    BasicBlock *BB = TI.getParent();
+
+    // Mark all feasible successors executable...
+    for (unsigned i = 0, e = SuccFeasible.size(); i != e; ++i)
+      if (SuccFeasible[i])
+        markEdgeExecutable(BB, TI.getSuccessor(i));
+  }
 };
 
 } // end namespace llvm
 
 #endif // LLVM_ANALYSIS_SPARSEPROPAGATION_H

lib/Analysis/CMakeLists.txt

add_llvm_library(LLVMAnalysis
   PtrUseVisitor.cpp
   RegionInfo.cpp
   RegionPass.cpp
   RegionPrinter.cpp
   ScalarEvolution.cpp
   ScalarEvolutionAliasAnalysis.cpp
   ScalarEvolutionExpander.cpp
   ScalarEvolutionNormalization.cpp
-  SparsePropagation.cpp
   TargetLibraryInfo.cpp
   TargetTransformInfo.cpp
   Trace.cpp
   TypeBasedAliasAnalysis.cpp
   TypeMetadataUtils.cpp
   ScopedNoAliasAA.cpp
   ValueLattice.cpp
   ValueTracking.cpp
   VectorUtils.cpp
 
   ADDITIONAL_HEADER_DIRS
   ${LLVM_MAIN_INCLUDE_DIR}/llvm/Analysis
 
   DEPENDS
   intrinsics_gen
   )

lib/Analysis/SparsePropagation.cpp

-//===- SparsePropagation.cpp - Sparse Conditional Property Propagation ----===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This file implements an abstract sparse conditional propagation algorithm,
-// modeled after SCCP, but with a customizable lattice function.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/Analysis/SparsePropagation.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/IR/Argument.h"
-#include "llvm/IR/BasicBlock.h"
-#include "llvm/IR/Constant.h"
-#include "llvm/IR/Constants.h"
-#include "llvm/IR/Function.h"
-#include "llvm/IR/InstrTypes.h"
-#include "llvm/IR/Instruction.h"
-#include "llvm/IR/Instructions.h"
-#include "llvm/IR/User.h"
-#include "llvm/Support/Casting.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/raw_ostream.h"
-
-using namespace llvm;
-
-#define DEBUG_TYPE "sparseprop"
-
-//===----------------------------------------------------------------------===//
-//                  AbstractLatticeFunction Implementation
-//===----------------------------------------------------------------------===//
-
-template <class LatticeVal>
-AbstractLatticeFunction<LatticeVal>::~AbstractLatticeFunction() = default;
-
-/// PrintValue - Render the specified lattice value to the specified stream.
-template <class LatticeVal>
-void AbstractLatticeFunction<LatticeVal>::PrintValue(LatticeVal V,
-                                                     raw_ostream &OS) {
-  if (V == UndefVal)
-    OS << "undefined";
-  else if (V == OverdefinedVal)
-    OS << "overdefined";
-  else if (V == UntrackedVal)
-    OS << "untracked";
-  else
-    OS << "unknown lattice value";
-}
-
-//===----------------------------------------------------------------------===//
-//                          SparseSolver Implementation
-//===----------------------------------------------------------------------===//
-
-/// getValueState - Return the LatticeVal object that corresponds to the
-/// value, initializing the value's state if it hasn't been entered into the
-/// map yet.   This function is necessary because not all values should start
-/// out in the underdefined state... Arguments should be overdefined, and
-/// constants should be marked as constants.
-template <class LatticeVal>
-LatticeVal SparseSolver<LatticeVal>::getValueState(Value *V) {
-  auto I = ValueState.find(V);
-  if (I != ValueState.end()) return I->second;  // Common case, in the map
-  
-  LatticeVal LV;
-  if (LatticeFunc->IsUntrackedValue(V))
-    return LatticeFunc->getUntrackedVal();
-  else if (Constant *C = dyn_cast<Constant>(V))
-    LV = LatticeFunc->ComputeConstant(C);
-  else if (Argument *A = dyn_cast<Argument>(V))
-    LV = LatticeFunc->ComputeArgument(A);
-  else if (!isa<Instruction>(V))
-    // All other non-instructions are overdefined.
-    LV = LatticeFunc->getOverdefinedVal();
-  else
-    // All instructions are underdefined by default.
-    LV = LatticeFunc->getUndefVal();
-  
-  // If this value is untracked, don't add it to the map.
-  if (LV == LatticeFunc->getUntrackedVal())
-    return LV;
-  return ValueState[V] = LV;
-}
-
-/// UpdateState - When the state for some instruction is potentially updated,
-/// this function notices and adds I to the worklist if needed.
-template <class LatticeVal>
-void SparseSolver<LatticeVal>::UpdateState(Instruction &Inst, LatticeVal V) {
-  auto I = ValueState.find(&Inst);
-  if (I != ValueState.end() && I->second == V)
-    return;  // No change.
-  
-  // An update.  Visit uses of I.
-  ValueState[&Inst] = V;
-  InstWorkList.push_back(&Inst);
-}
-
-/// MarkBlockExecutable - This method can be used by clients to mark all of
-/// the blocks that are known to be intrinsically live in the processed unit.
-template <class LatticeVal>
-void SparseSolver<LatticeVal>::MarkBlockExecutable(BasicBlock *BB) {
-  DEBUG(dbgs() << "Marking Block Executable: " << BB->getName() << "\n");
-  BBExecutable.insert(BB);   // Basic block is executable!
-  BBWorkList.push_back(BB);  // Add the block to the work list!
-}
-
-/// markEdgeExecutable - Mark a basic block as executable, adding it to the BB
-/// work list if it is not already executable...
-template <class LatticeVal>
-void SparseSolver<LatticeVal>::markEdgeExecutable(BasicBlock *Source,
-                                                  BasicBlock *Dest) {
-  if (!KnownFeasibleEdges.insert(Edge(Source, Dest)).second)
-    return;  // This edge is already known to be executable!
-  
-  DEBUG(dbgs() << "Marking Edge Executable: " << Source->getName()
-        << " -> " << Dest->getName() << "\n");
-
-  if (BBExecutable.count(Dest)) {
-    // The destination is already executable, but we just made an edge
-    // feasible that wasn't before.  Revisit the PHI nodes in the block
-    // because they have potentially new operands.
-    for (BasicBlock::iterator I = Dest->begin(); isa<PHINode>(I); ++I)
-      visitPHINode(*cast<PHINode>(I));
-  } else {
-    MarkBlockExecutable(Dest);
-  }
-}
-
-/// getFeasibleSuccessors - Return a vector of booleans to indicate which
-/// successors are reachable from a given terminator instruction.
-template <class LatticeVal>
-void SparseSolver<LatticeVal>::getFeasibleSuccessors(
-    TerminatorInst &TI, SmallVectorImpl<bool> &Succs, bool AggressiveUndef) {
-  Succs.resize(TI.getNumSuccessors());
-  if (TI.getNumSuccessors() == 0) return;
-  
-  if (BranchInst *BI = dyn_cast<BranchInst>(&TI)) {
-    if (BI->isUnconditional()) {
-      Succs[0] = true;
-      return;
-    }
-    
-    LatticeVal BCValue;
-    if (AggressiveUndef)
-      BCValue = getValueState(BI->getCondition());
-    else
-      BCValue = getLatticeState(BI->getCondition());
-    
-    if (BCValue == LatticeFunc->getOverdefinedVal() ||
-        BCValue == LatticeFunc->getUntrackedVal()) {
-      // Overdefined condition variables can branch either way.
-      Succs[0] = Succs[1] = true;
-      return;
-    }
-
-    // If undefined, neither is feasible yet.
-    if (BCValue == LatticeFunc->getUndefVal())
-      return;
-
-    Constant *C = LatticeFunc->GetConstant(BCValue, BI->getCondition(), *this);
-    if (!C || !isa<ConstantInt>(C)) {
-      // Non-constant values can go either way.
-      Succs[0] = Succs[1] = true;
-      return;
-    }
-
-    // Constant condition variables mean the branch can only go a single way
-    Succs[C->isNullValue()] = true;
-    return;
-  }
-  
-  if (isa<InvokeInst>(TI)) {
-    // Invoke instructions successors are always executable.
-    // TODO: Could ask the lattice function if the value can throw.
-    Succs[0] = Succs[1] = true;
-    return;
-  }
-  
-  if (isa<IndirectBrInst>(TI)) {
-    Succs.assign(Succs.size(), true);
-    return;
-  }
-  
-  SwitchInst &SI = cast<SwitchInst>(TI);
-  LatticeVal SCValue;
-  if (AggressiveUndef)
-    SCValue = getValueState(SI.getCondition());
-  else
-    SCValue = getLatticeState(SI.getCondition());
-  
-  if (SCValue == LatticeFunc->getOverdefinedVal() ||
-      SCValue == LatticeFunc->getUntrackedVal()) {
-    // All destinations are executable!
-    Succs.assign(TI.getNumSuccessors(), true);
-    return;
-  }
-  
-  // If undefined, neither is feasible yet.
-  if (SCValue == LatticeFunc->getUndefVal())
-    return;
-  
-  Constant *C = LatticeFunc->GetConstant(SCValue, SI.getCondition(), *this);
-  if (!C || !isa<ConstantInt>(C)) {
-    // All destinations are executable!
-    Succs.assign(TI.getNumSuccessors(), true);
-    return;
-  }
-  SwitchInst::CaseHandle Case = *SI.findCaseValue(cast<ConstantInt>(C));
-  Succs[Case.getSuccessorIndex()] = true;
-}
-
-/// isEdgeFeasible - Return true if the control flow edge from the 'From'
-/// basic block to the 'To' basic block is currently feasible...
-template <class LatticeVal>
-bool SparseSolver<LatticeVal>::isEdgeFeasible(BasicBlock *From, BasicBlock *To,
-                                              bool AggressiveUndef) {
-  SmallVector<bool, 16> SuccFeasible;
-  TerminatorInst *TI = From->getTerminator();
-  getFeasibleSuccessors(*TI, SuccFeasible, AggressiveUndef);
-  
-  for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
-    if (TI->getSuccessor(i) == To && SuccFeasible[i])
-      return true;
-  
-  return false;
-}
-
-template <class LatticeVal>
-void SparseSolver<LatticeVal>::visitTerminatorInst(TerminatorInst &TI) {
-  SmallVector<bool, 16> SuccFeasible;
-  getFeasibleSuccessors(TI, SuccFeasible, true);
-  
-  BasicBlock *BB = TI.getParent();
-  
-  // Mark all feasible successors executable...
-  for (unsigned i = 0, e = SuccFeasible.size(); i != e; ++i)
-    if (SuccFeasible[i])
-      markEdgeExecutable(BB, TI.getSuccessor(i));
-}
-
-template <class LatticeVal>
-void SparseSolver<LatticeVal>::visitPHINode(PHINode &PN) {
-  // The lattice function may store more information on a PHINode than could be
-  // computed from its incoming values.  For example, SSI form stores its sigma
-  // functions as PHINodes with a single incoming value.
-  if (LatticeFunc->IsSpecialCasedPHI(&PN)) {
-    LatticeVal IV = LatticeFunc->ComputeInstructionState(PN, *this);
-    if (IV != LatticeFunc->getUntrackedVal())
-      UpdateState(PN, IV);
-    return;
-  }
-
-  LatticeVal PNIV = getValueState(&PN);
-  LatticeVal Overdefined = LatticeFunc->getOverdefinedVal();
-  
-  // If this value is already overdefined (common) just return.
-  if (PNIV == Overdefined || PNIV == LatticeFunc->getUntrackedVal())
-    return;  // Quick exit
-  
-  // Super-extra-high-degree PHI nodes are unlikely to ever be interesting,
-  // and slow us down a lot.  Just mark them overdefined.
-  if (PN.getNumIncomingValues() > 64) {
-    UpdateState(PN, Overdefined);
-    return;
-  }
-  
-  // Look at all of the executable operands of the PHI node.  If any of them
-  // are overdefined, the PHI becomes overdefined as well.  Otherwise, ask the
-  // transfer function to give us the merge of the incoming values.
-  for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
-    // If the edge is not yet known to be feasible, it doesn't impact the PHI.
-    if (!isEdgeFeasible(PN.getIncomingBlock(i), PN.getParent(), true))
-      continue;
-    
-    // Merge in this value.
-    LatticeVal OpVal = getValueState(PN.getIncomingValue(i));
-    if (OpVal != PNIV)
-      PNIV = LatticeFunc->MergeValues(PNIV, OpVal);
-    
-    if (PNIV == Overdefined)
-      break;  // Rest of input values don't matter.
-  }
-
-  // Update the PHI with the compute value, which is the merge of the inputs.
-  UpdateState(PN, PNIV);
-}
-
-template <class LatticeVal>
-void SparseSolver<LatticeVal>::visitInst(Instruction &I) {
-  // PHIs are handled by the propagation logic, they are never passed into the
-  // transfer functions.
-  if (PHINode *PN = dyn_cast<PHINode>(&I))
-    return visitPHINode(*PN);
-  
-  // Otherwise, ask the transfer function what the result is.  If this is
-  // something that we care about, remember it.
-  LatticeVal IV = LatticeFunc->ComputeInstructionState(I, *this);
-  if (IV != LatticeFunc->getUntrackedVal())
-    UpdateState(I, IV);
-  
-  if (TerminatorInst *TI = dyn_cast<TerminatorInst>(&I))
-    visitTerminatorInst(*TI);
-}
-
-template <class LatticeVal> void SparseSolver<LatticeVal>::Solve(Function &F) {
-  MarkBlockExecutable(&F.getEntryBlock());
-  
-  // Process the work lists until they are empty!
-  while (!BBWorkList.empty() || !InstWorkList.empty()) {
-    // Process the instruction work list.
-    while (!InstWorkList.empty()) {
-      Instruction *I = InstWorkList.back();
-      InstWorkList.pop_back();
-
-      DEBUG(dbgs() << "\nPopped off I-WL: " << *I << "\n");
-
-      // "I" got into the work list because it made a transition.  See if any
-      // users are both live and in need of updating.
-      for (User *U : I->users()) {
-        Instruction *UI = cast<Instruction>(U);
-        if (BBExecutable.count(UI->getParent()))   // Inst is executable?
-          visitInst(*UI);
-      }
-    }
-
-    // Process the basic block work list.
-    while (!BBWorkList.empty()) {
-      BasicBlock *BB = BBWorkList.back();
-      BBWorkList.pop_back();
-
-      DEBUG(dbgs() << "\nPopped off BBWL: " << *BB);
-
-      // Notify all instructions in this basic block that they are newly
-      // executable.
-      for (Instruction &I : *BB)
-        visitInst(I);
-    }
-  }
-}
-
-template <class LatticeVal>
-void SparseSolver<LatticeVal>::Print(Function &F, raw_ostream &OS) const {
-  OS << "\nFUNCTION: " << F.getName() << "\n";
-  for (auto &BB : F) {
-    if (!BBExecutable.count(&BB))
-      OS << "INFEASIBLE: ";
-    OS << "\t";
-    if (BB.hasName())
-      OS << BB.getName() << ":\n";
-    else
-      OS << "; anon bb\n";
-    for (auto &I : BB) {
-      LatticeFunc->PrintValue(getLatticeState(&I), OS);
-      OS << I << "\n";
-    }
-    
-    OS << "\n";
-  }
-}