This is an archive of the discontinued LLVM Phabricator instance.

Differential D46916

[llvm-mca] Move the RegisterFile class into its own translation unit. NFC
ClosedPublic

Authored by mattd on May 15 2018, 4:33 PM.

Details

Reviewers
andreadb
RKSimon
courbet
Commits
rGb7972f88c75f: [llvm-mca] Move the RegisterFile class into its own translation unit. NFC
rL332493: [llvm-mca] Move the RegisterFile class into its own translation unit. NFC
Summary

This change will help us turn the DispatchUnit into its own stage.

Diff Detail

Event Timeline

mattd created this revision.May 15 2018, 4:33 PM
Herald added subscribers: gbedwell, tschuett, mgorny. · View Herald TranscriptMay 15 2018, 4:33 PM
mattd added a reviewer: courbet.May 15 2018, 4:33 PM
courbet accepted this revision.May 16 2018, 1:29 AM

yay, smaller files :)

This revision is now accepted and ready to land.May 16 2018, 1:29 AM
andreadb accepted this revision.May 16 2018, 1:33 AM

If the goal is to make the current DispatchUnit a DispatchStage, then this makes sense.

A couple of minor nits. Otherwise it looks good to me.

tools/llvm-mca/Dispatch.h
22

This include should stay in this file.

tools/llvm-mca/RegisterFile.h
23

This include file is not needed.
Instead, you should include llvm/MC/MCSchedule.h.

mattd updated this revision to Diff 147112.May 16 2018, 9:27 AM
mattd marked 2 inline comments as done.

Corrected the #include directives.

mattd added a comment.May 16 2018, 9:28 AM

Thanks for the reviews.

Closed by commit rL332493: [llvm-mca] Move the RegisterFile class into its own translation unit. NFC (authored by mattd). · Explain WhyMay 16 2018, 10:10 AM
This revision was automatically updated to reflect the committed changes.

Revision Contents

PathSize
tools/
llvm-mca/
1 line
138 lines
237 lines
162 lines
261 lines

Diff 147112

tools/llvm-mca/CMakeLists.txt

Show All 17 Linesadd_llvm_tool(llvm-mca
FetchStage.cpp FetchStage.cpp
HWEventListener.cpp HWEventListener.cpp
InstrBuilder.cpp InstrBuilder.cpp
Instruction.cpp Instruction.cpp
InstructionInfoView.cpp InstructionInfoView.cpp
InstructionTables.cpp InstructionTables.cpp
LSUnit.cpp LSUnit.cpp
llvm-mca.cpp llvm-mca.cpp
RegisterFile.cpp
RegisterFileStatistics.cpp RegisterFileStatistics.cpp
ResourcePressureView.cpp ResourcePressureView.cpp
RetireControlUnit.cpp RetireControlUnit.cpp
RetireControlUnitStatistics.cpp RetireControlUnitStatistics.cpp
Scheduler.cpp Scheduler.cpp
SchedulerStatistics.cpp SchedulerStatistics.cpp
Stage.cpp Stage.cpp
Support.cpp Support.cpp
SummaryView.cpp SummaryView.cpp
TimelineView.cpp TimelineView.cpp
View.cpp View.cpp
) )

tools/llvm-mca/Dispatch.h

//===----------------------- Dispatch.h -------------------------*- C++ -*-===// //===----------------------- Dispatch.h -------------------------*- C++ -*-===//
// //
// The LLVM Compiler Infrastructure // The LLVM Compiler Infrastructure
// //
// This file is distributed under the University of Illinois Open Source // This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details. // License. See LICENSE.TXT for details.
// //
//===----------------------------------------------------------------------===// //===----------------------------------------------------------------------===//
/// \file /// \file
/// ///
/// This file implements classes that are used to model register files, /// This file implements classes that are used to model reorder buffers and
/// reorder buffers and the hardware dispatch logic. /// the hardware dispatch logic.
/// ///
//===----------------------------------------------------------------------===// //===----------------------------------------------------------------------===//
#ifndef LLVM_TOOLS_LLVM_MCA_DISPATCH_H #ifndef LLVM_TOOLS_LLVM_MCA_DISPATCH_H
#define LLVM_TOOLS_LLVM_MCA_DISPATCH_H #define LLVM_TOOLS_LLVM_MCA_DISPATCH_H
#include "Instruction.h" #include "Instruction.h"
#include "RegisterFile.h"
#include "RetireControlUnit.h" #include "RetireControlUnit.h"
#include "llvm/MC/MCRegisterInfo.h" #include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCSubtargetInfo.h" #include "llvm/MC/MCSubtargetInfo.h"
andreadbUnsubmitted
Done
ReplyInline Actions

This include should stay in this file.

andreadb: This include should stay in this file.
#include <map>
namespace mca { namespace mca {
class WriteState; class WriteState;
class DispatchUnit;
class Scheduler; class Scheduler;
class Backend; class Backend;
/// Manages hardware register files, and tracks data dependencies
/// between registers.
class RegisterFile {
const llvm::MCRegisterInfo &MRI;
// Each register file is described by an instance of RegisterMappingTracker.
// RegisterMappingTracker tracks the number of register mappings dynamically
// allocated during the execution.
struct RegisterMappingTracker {
// Total number of register mappings that are available for register
// renaming. A value of zero for this field means: this register file has
// an unbounded number of registers.
const unsigned TotalMappings;
// Number of mappings that are currently in use.
unsigned NumUsedMappings;
RegisterMappingTracker(unsigned NumMappings)
: TotalMappings(NumMappings), NumUsedMappings(0) {}
};
// This is where information related to the various register files is kept.
// This set always contains at least one register file at index #0. That
// register file "sees" all the physical registers declared by the target, and
// (by default) it allows an unbounded number of mappings.
// Users can limit the number of mappings that can be created by register file
// #0 through the command line flag `-register-file-size`.
llvm::SmallVector<RegisterMappingTracker, 4> RegisterFiles;
// This pair is used to identify the owner of a physical register, as well as
// the cost of using that register file.
using IndexPlusCostPairTy = std::pair<unsigned, unsigned>;
// RegisterMapping objects are mainly used to track physical register
// definitions. A WriteState object describes a register definition, and it is
// used to track RAW dependencies (see Instruction.h). A RegisterMapping
// object also specifies the set of register files. The mapping between
// physreg and register files is done using a "register file mask".
//
// A register file index identifies a user defined register file.
// There is one index per RegisterMappingTracker, and index #0 is reserved to
// the default unified register file.
//
// This implementation does not allow overlapping register files. The only
// register file that is allowed to overlap with other register files is
// register file #0.
using RegisterMapping = std::pair<WriteState *, IndexPlusCostPairTy>;
// This map contains one entry for each physical register defined by the
// processor scheduling model.
std::vector<RegisterMapping> RegisterMappings;
// This method creates a new RegisterMappingTracker for a register file that
// contains all the physical registers specified by the register classes in
// the 'RegisterClasses' set.
//
// The long term goal is to let scheduling models optionally describe register
// files via tablegen definitions. This is still a work in progress.
// For example, here is how a tablegen definition for a x86 FP register file
// that features AVX might look like:
//
// def FPRegisterFile : RegisterFile<[VR128RegClass, VR256RegClass], 60>
//
// Here FPRegisterFile contains all the registers defined by register class
// VR128RegClass and VR256RegClass. FPRegisterFile implements 60
// registers which can be used for register renaming purpose.
//
// The list of register classes is then converted by the tablegen backend into
// a list of register class indices. That list, along with the number of
// available mappings, is then used to create a new RegisterMappingTracker.
void
addRegisterFile(llvm::ArrayRef<llvm::MCRegisterCostEntry> RegisterClasses,
unsigned NumPhysRegs);
// Allocates register mappings in register file specified by the
// IndexPlusCostPairTy object. This method is called from addRegisterMapping.
void allocatePhysRegs(IndexPlusCostPairTy IPC,
llvm::MutableArrayRef<unsigned> UsedPhysRegs);
// Removes a previously allocated mapping from the register file referenced
// by the IndexPlusCostPairTy object. This method is called from
// invalidateRegisterMapping.
void freePhysRegs(IndexPlusCostPairTy IPC,
llvm::MutableArrayRef<unsigned> FreedPhysRegs);
// Create an instance of RegisterMappingTracker for every register file
// specified by the processor model.
// If no register file is specified, then this method creates a single
// register file with an unbounded number of registers.
void initialize(const llvm::MCSchedModel &SM, unsigned NumRegs);
public:
RegisterFile(const llvm::MCSchedModel &SM, const llvm::MCRegisterInfo &mri,
unsigned NumRegs = 0)
: MRI(mri), RegisterMappings(mri.getNumRegs(), {nullptr, {0, 0}}) {
initialize(SM, NumRegs);
}
// This method updates the data dependency graph by inserting a new register
// definition. This method is also responsible for updating the number of used
// physical registers in the register file(s). The number of physical
// registers is updated only if flag ShouldAllocatePhysRegs is set.
void addRegisterWrite(WriteState &WS,
llvm::MutableArrayRef<unsigned> UsedPhysRegs,
bool ShouldAllocatePhysRegs = true);
// Updates the data dependency graph by removing a write. It also updates the
// internal state of the register file(s) by freeing physical registers.
// The number of physical registers is updated only if flag ShouldFreePhysRegs
// is set.
void removeRegisterWrite(const WriteState &WS,
llvm::MutableArrayRef<unsigned> FreedPhysRegs,
bool ShouldFreePhysRegs = true);
// Checks if there are enough microarchitectural registers in the register
// files. Returns a "response mask" where each bit is the response from a
// RegisterMappingTracker.
// For example: if all register files are available, then the response mask
// is a bitmask of all zeroes. If Instead register file #1 is not available,
// then the response mask is 0b10.
unsigned isAvailable(llvm::ArrayRef<unsigned> Regs) const;
void collectWrites(llvm::SmallVectorImpl<WriteState *> &Writes,
unsigned RegID) const;
void updateOnRead(ReadState &RS, unsigned RegID);
unsigned getNumRegisterFiles() const { return RegisterFiles.size(); }
#ifndef NDEBUG
void dump() const;
#endif
};
// Implements the hardware dispatch logic. // Implements the hardware dispatch logic.
// //
// This class is responsible for the dispatch stage, in which instructions are // This class is responsible for the dispatch stage, in which instructions are
// dispatched in groups to the Scheduler. An instruction can be dispatched if // dispatched in groups to the Scheduler. An instruction can be dispatched if
// functional units are available. // functional units are available.
// To be more specific, an instruction can be dispatched to the Scheduler if: // To be more specific, an instruction can be dispatched to the Scheduler if:
// 1) There are enough entries in the reorder buffer (implemented by class // 1) There are enough entries in the reorder buffer (implemented by class
// RetireControlUnit) to accomodate all opcodes. // RetireControlUnit) to accomodate all opcodes.
▲ Show 20 Lines • Show All 84 Lines • Show Last 20 Lines

tools/llvm-mca/Dispatch.cpp

//===--------------------- Dispatch.cpp -------------------------*- C++ -*-===// //===--------------------- Dispatch.cpp -------------------------*- C++ -*-===//
// //
// The LLVM Compiler Infrastructure // The LLVM Compiler Infrastructure
// //
// This file is distributed under the University of Illinois Open Source // This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details. // License. See LICENSE.TXT for details.
// //
//===----------------------------------------------------------------------===// //===----------------------------------------------------------------------===//
/// \file /// \file
/// ///
/// This file implements methods declared by class RegisterFile and /// This file implements methods declared by the DispatchUnit class.
/// DispatchUnit.
/// ///
//===----------------------------------------------------------------------===// //===----------------------------------------------------------------------===//
#include "Dispatch.h" #include "Dispatch.h"
#include "Backend.h" #include "Backend.h"
#include "HWEventListener.h" #include "HWEventListener.h"
#include "Scheduler.h" #include "Scheduler.h"
#include "llvm/Support/Debug.h" #include "llvm/Support/Debug.h"
using namespace llvm; using namespace llvm;
#define DEBUG_TYPE "llvm-mca" #define DEBUG_TYPE "llvm-mca"
namespace mca { namespace mca {
void RegisterFile::initialize(const MCSchedModel &SM, unsigned NumRegs) {
// Create a default register file that "sees" all the machine registers
// declared by the target. The number of physical registers in the default
// register file is set equal to `NumRegs`. A value of zero for `NumRegs`
// means: this register file has an unbounded number of physical registers.
addRegisterFile({} /* all registers */, NumRegs);
if (!SM.hasExtraProcessorInfo())
return;
// For each user defined register file, allocate a RegisterMappingTracker
// object. The size of every register file, as well as the mapping between
// register files and register classes is specified via tablegen.
const MCExtraProcessorInfo &Info = SM.getExtraProcessorInfo();
for (unsigned I = 0, E = Info.NumRegisterFiles; I < E; ++I) {
const MCRegisterFileDesc &RF = Info.RegisterFiles[I];
// Skip invalid register files with zero physical registers.
unsigned Length = RF.NumRegisterCostEntries;
if (!RF.NumPhysRegs)
continue;
// The cost of a register definition is equivalent to the number of
// physical registers that are allocated at register renaming stage.
const MCRegisterCostEntry *FirstElt =
&Info.RegisterCostTable[RF.RegisterCostEntryIdx];
addRegisterFile(ArrayRef<MCRegisterCostEntry>(FirstElt, Length),
RF.NumPhysRegs);
}
}
void RegisterFile::addRegisterFile(ArrayRef<MCRegisterCostEntry> Entries,
unsigned NumPhysRegs) {
// A default register file is always allocated at index #0. That register file
// is mainly used to count the total number of mappings created by all
// register files at runtime. Users can limit the number of available physical
// registers in register file #0 through the command line flag
// `-register-file-size`.
unsigned RegisterFileIndex = RegisterFiles.size();
RegisterFiles.emplace_back(NumPhysRegs);
// Special case where there is no register class identifier in the set.
// An empty set of register classes means: this register file contains all
// the physical registers specified by the target.
if (Entries.empty()) {
for (std::pair<WriteState *, IndexPlusCostPairTy> &Mapping :
RegisterMappings)
Mapping.second = std::make_pair(RegisterFileIndex, 1U);
return;
}
// Now update the cost of individual registers.
for (const MCRegisterCostEntry &RCE : Entries) {
const MCRegisterClass &RC = MRI.getRegClass(RCE.RegisterClassID);
for (const MCPhysReg Reg : RC) {
IndexPlusCostPairTy &Entry = RegisterMappings[Reg].second;
if (Entry.first) {
// The only register file that is allowed to overlap is the default
// register file at index #0. The analysis is inaccurate if register
// files overlap.
errs() << "warning: register " << MRI.getName(Reg)
<< " defined in multiple register files.";
}
Entry.first = RegisterFileIndex;
Entry.second = RCE.Cost;
}
}
}
void RegisterFile::allocatePhysRegs(IndexPlusCostPairTy Entry,
MutableArrayRef<unsigned> UsedPhysRegs) {
unsigned RegisterFileIndex = Entry.first;
unsigned Cost = Entry.second;
if (RegisterFileIndex) {
RegisterMappingTracker &RMT = RegisterFiles[RegisterFileIndex];
RMT.NumUsedMappings += Cost;
UsedPhysRegs[RegisterFileIndex] += Cost;
}
// Now update the default register mapping tracker.
RegisterFiles[0].NumUsedMappings += Cost;
UsedPhysRegs[0] += Cost;
}
void RegisterFile::freePhysRegs(IndexPlusCostPairTy Entry,
MutableArrayRef<unsigned> FreedPhysRegs) {
unsigned RegisterFileIndex = Entry.first;
unsigned Cost = Entry.second;
if (RegisterFileIndex) {
RegisterMappingTracker &RMT = RegisterFiles[RegisterFileIndex];
RMT.NumUsedMappings -= Cost;
FreedPhysRegs[RegisterFileIndex] += Cost;
}
// Now update the default register mapping tracker.
RegisterFiles[0].NumUsedMappings -= Cost;
FreedPhysRegs[0] += Cost;
}
void RegisterFile::addRegisterWrite(WriteState &WS,
MutableArrayRef<unsigned> UsedPhysRegs,
bool ShouldAllocatePhysRegs) {
unsigned RegID = WS.getRegisterID();
assert(RegID && "Adding an invalid register definition?");
RegisterMapping &Mapping = RegisterMappings[RegID];
Mapping.first = &WS;
for (MCSubRegIterator I(RegID, &MRI); I.isValid(); ++I)
RegisterMappings[*I].first = &WS;
// No physical registers are allocated for instructions that are optimized in
// hardware. For example, zero-latency data-dependency breaking instructions
// don't consume physical registers.
if (ShouldAllocatePhysRegs)
allocatePhysRegs(Mapping.second, UsedPhysRegs);
// If this is a partial update, then we are done.
if (!WS.fullyUpdatesSuperRegs())
return;
for (MCSuperRegIterator I(RegID, &MRI); I.isValid(); ++I)
RegisterMappings[*I].first = &WS;
}
void RegisterFile::removeRegisterWrite(const WriteState &WS,
MutableArrayRef<unsigned> FreedPhysRegs,
bool ShouldFreePhysRegs) {
unsigned RegID = WS.getRegisterID();
bool ShouldInvalidateSuperRegs = WS.fullyUpdatesSuperRegs();
assert(RegID != 0 && "Invalidating an already invalid register?");
assert(WS.getCyclesLeft() != -512 &&
"Invalidating a write of unknown cycles!");
assert(WS.getCyclesLeft() <= 0 && "Invalid cycles left for this write!");
RegisterMapping &Mapping = RegisterMappings[RegID];
if (!Mapping.first)
return;
if (ShouldFreePhysRegs)
freePhysRegs(Mapping.second, FreedPhysRegs);
if (Mapping.first == &WS)
Mapping.first = nullptr;
for (MCSubRegIterator I(RegID, &MRI); I.isValid(); ++I)
if (RegisterMappings[*I].first == &WS)
RegisterMappings[*I].first = nullptr;
if (!ShouldInvalidateSuperRegs)
return;
for (MCSuperRegIterator I(RegID, &MRI); I.isValid(); ++I)
if (RegisterMappings[*I].first == &WS)
RegisterMappings[*I].first = nullptr;
}
void RegisterFile::collectWrites(SmallVectorImpl<WriteState *> &Writes,
unsigned RegID) const {
assert(RegID && RegID < RegisterMappings.size());
WriteState *WS = RegisterMappings[RegID].first;
if (WS) {
LLVM_DEBUG(dbgs() << "Found a dependent use of RegID=" << RegID << '\n');
Writes.push_back(WS);
}
// Handle potential partial register updates.
for (MCSubRegIterator I(RegID, &MRI); I.isValid(); ++I) {
WS = RegisterMappings[*I].first;
if (WS && std::find(Writes.begin(), Writes.end(), WS) == Writes.end()) {
LLVM_DEBUG(dbgs() << "Found a dependent use of subReg " << *I
<< " (part of " << RegID << ")\n");
Writes.push_back(WS);
}
}
}
unsigned RegisterFile::isAvailable(ArrayRef<unsigned> Regs) const {
SmallVector<unsigned, 4> NumPhysRegs(getNumRegisterFiles());
// Find how many new mappings must be created for each register file.
for (const unsigned RegID : Regs) {
const IndexPlusCostPairTy &Entry = RegisterMappings[RegID].second;
if (Entry.first)
NumPhysRegs[Entry.first] += Entry.second;
NumPhysRegs[0] += Entry.second;
}
unsigned Response = 0;
for (unsigned I = 0, E = getNumRegisterFiles(); I < E; ++I) {
unsigned NumRegs = NumPhysRegs[I];
if (!NumRegs)
continue;
const RegisterMappingTracker &RMT = RegisterFiles[I];
if (!RMT.TotalMappings) {
// The register file has an unbounded number of microarchitectural
// registers.
continue;
}
if (RMT.TotalMappings < NumRegs) {
// The current register file is too small. This may occur if the number of
// microarchitectural registers in register file #0 was changed by the
// users via flag -reg-file-size. Alternatively, the scheduling model
// specified a too small number of registers for this register file.
report_fatal_error(
"Not enough microarchitectural registers in the register file");
}
if (RMT.TotalMappings < (RMT.NumUsedMappings + NumRegs))
Response |= (1U << I);
}
return Response;
}
#ifndef NDEBUG
void RegisterFile::dump() const {
for (unsigned I = 0, E = MRI.getNumRegs(); I < E; ++I) {
const RegisterMapping &RM = RegisterMappings[I];
dbgs() << MRI.getName(I) << ", " << I << ", Map=" << RM.second.first
<< ", ";
if (RM.first)
RM.first->dump();
else
dbgs() << "(null)\n";
}
for (unsigned I = 0, E = getNumRegisterFiles(); I < E; ++I) {
dbgs() << "Register File #" << I;
const RegisterMappingTracker &RMT = RegisterFiles[I];
dbgs() << "\n TotalMappings: " << RMT.TotalMappings
<< "\n NumUsedMappings: " << RMT.NumUsedMappings << '\n';
}
}
#endif
void DispatchUnit::notifyInstructionDispatched(const InstRef &IR, void DispatchUnit::notifyInstructionDispatched(const InstRef &IR,
ArrayRef<unsigned> UsedRegs) { ArrayRef<unsigned> UsedRegs) {
LLVM_DEBUG(dbgs() << "[E] Instruction Dispatched: " << IR << '\n'); LLVM_DEBUG(dbgs() << "[E] Instruction Dispatched: " << IR << '\n');
Owner->notifyInstructionEvent(HWInstructionDispatchedEvent(IR, UsedRegs)); Owner->notifyInstructionEvent(HWInstructionDispatchedEvent(IR, UsedRegs));
} }
void DispatchUnit::notifyInstructionRetired(const InstRef &IR) { void DispatchUnit::notifyInstructionRetired(const InstRef &IR) {
LLVM_DEBUG(dbgs() << "[E] Instruction Retired: " << IR << '\n'); LLVM_DEBUG(dbgs() << "[E] Instruction Retired: " << IR << '\n');
▲ Show 20 Lines • Show All 117 Lines • Show Last 20 Lines

tools/llvm-mca/RegisterFile.h

  • This file was added.
//===--------------------- RegisterFile.h -----------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
/// \file
///
/// This file defines a register mapping file class. This class is responsible
/// for managing hardware register files and the tracking of data dependencies
/// between registers.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_TOOLS_LLVM_MCA_REGISTER_FILE_H
#define LLVM_TOOLS_LLVM_MCA_REGISTER_FILE_H
#include "llvm/ADT/SmallVector.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCSchedule.h"
andreadbUnsubmitted
Done
ReplyInline Actions

This include file is not needed.
Instead, you should include llvm/MC/MCSchedule.h.

andreadb: This include file is not needed. Instead, you should include `llvm/MC/MCSchedule.h`.
namespace mca {
class ReadState;
class WriteState;
/// Manages hardware register files, and tracks data dependencies
/// between registers.
class RegisterFile {
const llvm::MCRegisterInfo &MRI;
// Each register file is described by an instance of RegisterMappingTracker.
// RegisterMappingTracker tracks the number of register mappings dynamically
// allocated during the execution.
struct RegisterMappingTracker {
// Total number of register mappings that are available for register
// renaming. A value of zero for this field means: this register file has
// an unbounded number of registers.
const unsigned TotalMappings;
// Number of mappings that are currently in use.
unsigned NumUsedMappings;
RegisterMappingTracker(unsigned NumMappings)
: TotalMappings(NumMappings), NumUsedMappings(0) {}
};
// This is where information related to the various register files is kept.
// This set always contains at least one register file at index #0. That
// register file "sees" all the physical registers declared by the target, and
// (by default) it allows an unbounded number of mappings.
// Users can limit the number of mappings that can be created by register file
// #0 through the command line flag `-register-file-size`.
llvm::SmallVector<RegisterMappingTracker, 4> RegisterFiles;
// This pair is used to identify the owner of a physical register, as well as
// the cost of using that register file.
using IndexPlusCostPairTy = std::pair<unsigned, unsigned>;
// RegisterMapping objects are mainly used to track physical register
// definitions. A WriteState object describes a register definition, and it is
// used to track RAW dependencies (see Instruction.h). A RegisterMapping
// object also specifies the set of register files. The mapping between
// physreg and register files is done using a "register file mask".
//
// A register file index identifies a user defined register file.
// There is one index per RegisterMappingTracker, and index #0 is reserved to
// the default unified register file.
//
// This implementation does not allow overlapping register files. The only
// register file that is allowed to overlap with other register files is
// register file #0.
using RegisterMapping = std::pair<WriteState *, IndexPlusCostPairTy>;
// This map contains one entry for each physical register defined by the
// processor scheduling model.
std::vector<RegisterMapping> RegisterMappings;
// This method creates a new RegisterMappingTracker for a register file that
// contains all the physical registers specified by the register classes in
// the 'RegisterClasses' set.
//
// The long term goal is to let scheduling models optionally describe register
// files via tablegen definitions. This is still a work in progress.
// For example, here is how a tablegen definition for a x86 FP register file
// that features AVX might look like:
//
// def FPRegisterFile : RegisterFile<[VR128RegClass, VR256RegClass], 60>
//
// Here FPRegisterFile contains all the registers defined by register class
// VR128RegClass and VR256RegClass. FPRegisterFile implements 60
// registers which can be used for register renaming purpose.
//
// The list of register classes is then converted by the tablegen backend into
// a list of register class indices. That list, along with the number of
// available mappings, is then used to create a new RegisterMappingTracker.
void
addRegisterFile(llvm::ArrayRef<llvm::MCRegisterCostEntry> RegisterClasses,
unsigned NumPhysRegs);
// Allocates register mappings in register file specified by the
// IndexPlusCostPairTy object. This method is called from addRegisterMapping.
void allocatePhysRegs(IndexPlusCostPairTy IPC,
llvm::MutableArrayRef<unsigned> UsedPhysRegs);
// Removes a previously allocated mapping from the register file referenced
// by the IndexPlusCostPairTy object. This method is called from
// invalidateRegisterMapping.
void freePhysRegs(IndexPlusCostPairTy IPC,
llvm::MutableArrayRef<unsigned> FreedPhysRegs);
// Create an instance of RegisterMappingTracker for every register file
// specified by the processor model.
// If no register file is specified, then this method creates a single
// register file with an unbounded number of registers.
void initialize(const llvm::MCSchedModel &SM, unsigned NumRegs);
public:
RegisterFile(const llvm::MCSchedModel &SM, const llvm::MCRegisterInfo &mri,
unsigned NumRegs = 0)
: MRI(mri), RegisterMappings(mri.getNumRegs(), {nullptr, {0, 0}}) {
initialize(SM, NumRegs);
}
// This method updates the data dependency graph by inserting a new register
// definition. This method is also responsible for updating the number of used
// physical registers in the register file(s). The number of physical
// registers is updated only if flag ShouldAllocatePhysRegs is set.
void addRegisterWrite(WriteState &WS,
llvm::MutableArrayRef<unsigned> UsedPhysRegs,
bool ShouldAllocatePhysRegs = true);
// Updates the data dependency graph by removing a write. It also updates the
// internal state of the register file(s) by freeing physical registers.
// The number of physical registers is updated only if flag ShouldFreePhysRegs
// is set.
void removeRegisterWrite(const WriteState &WS,
llvm::MutableArrayRef<unsigned> FreedPhysRegs,
bool ShouldFreePhysRegs = true);
// Checks if there are enough microarchitectural registers in the register
// files. Returns a "response mask" where each bit is the response from a
// RegisterMappingTracker.
// For example: if all register files are available, then the response mask
// is a bitmask of all zeroes. If Instead register file #1 is not available,
// then the response mask is 0b10.
unsigned isAvailable(llvm::ArrayRef<unsigned> Regs) const;
void collectWrites(llvm::SmallVectorImpl<WriteState *> &Writes,
unsigned RegID) const;
void updateOnRead(ReadState &RS, unsigned RegID);
unsigned getNumRegisterFiles() const { return RegisterFiles.size(); }
#ifndef NDEBUG
void dump() const;
#endif
};
} // namespace mca
#endif // LLVM_TOOLS_LLVM_MCA_REGISTER_FILE_H

tools/llvm-mca/RegisterFile.cpp

  • This file was added.
//===--------------------- RegisterFile.cpp ---------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
/// \file
///
/// This file defines a register mapping file class. This class is responsible
/// for managing hardware register files and the tracking of data dependencies
/// between registers.
///
//===----------------------------------------------------------------------===//
#include "RegisterFile.h"
#include "Instruction.h"
#include "llvm/Support/Debug.h"
using namespace llvm;
#define DEBUG_TYPE "llvm-mca"
namespace mca {
void RegisterFile::initialize(const MCSchedModel &SM, unsigned NumRegs) {
// Create a default register file that "sees" all the machine registers
// declared by the target. The number of physical registers in the default
// register file is set equal to `NumRegs`. A value of zero for `NumRegs`
// means: this register file has an unbounded number of physical registers.
addRegisterFile({} /* all registers */, NumRegs);
if (!SM.hasExtraProcessorInfo())
return;
// For each user defined register file, allocate a RegisterMappingTracker
// object. The size of every register file, as well as the mapping between
// register files and register classes is specified via tablegen.
const MCExtraProcessorInfo &Info = SM.getExtraProcessorInfo();
for (unsigned I = 0, E = Info.NumRegisterFiles; I < E; ++I) {
const MCRegisterFileDesc &RF = Info.RegisterFiles[I];
// Skip invalid register files with zero physical registers.
unsigned Length = RF.NumRegisterCostEntries;
if (!RF.NumPhysRegs)
continue;
// The cost of a register definition is equivalent to the number of
// physical registers that are allocated at register renaming stage.
const MCRegisterCostEntry *FirstElt =
&Info.RegisterCostTable[RF.RegisterCostEntryIdx];
addRegisterFile(ArrayRef<MCRegisterCostEntry>(FirstElt, Length),
RF.NumPhysRegs);
}
}
void RegisterFile::addRegisterFile(ArrayRef<MCRegisterCostEntry> Entries,
unsigned NumPhysRegs) {
// A default register file is always allocated at index #0. That register file
// is mainly used to count the total number of mappings created by all
// register files at runtime. Users can limit the number of available physical
// registers in register file #0 through the command line flag
// `-register-file-size`.
unsigned RegisterFileIndex = RegisterFiles.size();
RegisterFiles.emplace_back(NumPhysRegs);
// Special case where there is no register class identifier in the set.
// An empty set of register classes means: this register file contains all
// the physical registers specified by the target.
if (Entries.empty()) {
for (std::pair<WriteState *, IndexPlusCostPairTy> &Mapping :
RegisterMappings)
Mapping.second = std::make_pair(RegisterFileIndex, 1U);
return;
}
// Now update the cost of individual registers.
for (const MCRegisterCostEntry &RCE : Entries) {
const MCRegisterClass &RC = MRI.getRegClass(RCE.RegisterClassID);
for (const MCPhysReg Reg : RC) {
IndexPlusCostPairTy &Entry = RegisterMappings[Reg].second;
if (Entry.first) {
// The only register file that is allowed to overlap is the default
// register file at index #0. The analysis is inaccurate if register
// files overlap.
errs() << "warning: register " << MRI.getName(Reg)
<< " defined in multiple register files.";
}
Entry.first = RegisterFileIndex;
Entry.second = RCE.Cost;
}
}
}
void RegisterFile::allocatePhysRegs(IndexPlusCostPairTy Entry,
MutableArrayRef<unsigned> UsedPhysRegs) {
unsigned RegisterFileIndex = Entry.first;
unsigned Cost = Entry.second;
if (RegisterFileIndex) {
RegisterMappingTracker &RMT = RegisterFiles[RegisterFileIndex];
RMT.NumUsedMappings += Cost;
UsedPhysRegs[RegisterFileIndex] += Cost;
}
// Now update the default register mapping tracker.
RegisterFiles[0].NumUsedMappings += Cost;
UsedPhysRegs[0] += Cost;
}
void RegisterFile::freePhysRegs(IndexPlusCostPairTy Entry,
MutableArrayRef<unsigned> FreedPhysRegs) {
unsigned RegisterFileIndex = Entry.first;
unsigned Cost = Entry.second;
if (RegisterFileIndex) {
RegisterMappingTracker &RMT = RegisterFiles[RegisterFileIndex];
RMT.NumUsedMappings -= Cost;
FreedPhysRegs[RegisterFileIndex] += Cost;
}
// Now update the default register mapping tracker.
RegisterFiles[0].NumUsedMappings -= Cost;
FreedPhysRegs[0] += Cost;
}
void RegisterFile::addRegisterWrite(WriteState &WS,
MutableArrayRef<unsigned> UsedPhysRegs,
bool ShouldAllocatePhysRegs) {
unsigned RegID = WS.getRegisterID();
assert(RegID && "Adding an invalid register definition?");
RegisterMapping &Mapping = RegisterMappings[RegID];
Mapping.first = &WS;
for (MCSubRegIterator I(RegID, &MRI); I.isValid(); ++I)
RegisterMappings[*I].first = &WS;
// No physical registers are allocated for instructions that are optimized in
// hardware. For example, zero-latency data-dependency breaking instructions
// don't consume physical registers.
if (ShouldAllocatePhysRegs)
allocatePhysRegs(Mapping.second, UsedPhysRegs);
// If this is a partial update, then we are done.
if (!WS.fullyUpdatesSuperRegs())
return;
for (MCSuperRegIterator I(RegID, &MRI); I.isValid(); ++I)
RegisterMappings[*I].first = &WS;
}
void RegisterFile::removeRegisterWrite(const WriteState &WS,
MutableArrayRef<unsigned> FreedPhysRegs,
bool ShouldFreePhysRegs) {
unsigned RegID = WS.getRegisterID();
bool ShouldInvalidateSuperRegs = WS.fullyUpdatesSuperRegs();
assert(RegID != 0 && "Invalidating an already invalid register?");
assert(WS.getCyclesLeft() != -512 &&
"Invalidating a write of unknown cycles!");
assert(WS.getCyclesLeft() <= 0 && "Invalid cycles left for this write!");
RegisterMapping &Mapping = RegisterMappings[RegID];
if (!Mapping.first)
return;
if (ShouldFreePhysRegs)
freePhysRegs(Mapping.second, FreedPhysRegs);
if (Mapping.first == &WS)
Mapping.first = nullptr;
for (MCSubRegIterator I(RegID, &MRI); I.isValid(); ++I)
if (RegisterMappings[*I].first == &WS)
RegisterMappings[*I].first = nullptr;
if (!ShouldInvalidateSuperRegs)
return;
for (MCSuperRegIterator I(RegID, &MRI); I.isValid(); ++I)
if (RegisterMappings[*I].first == &WS)
RegisterMappings[*I].first = nullptr;
}
void RegisterFile::collectWrites(SmallVectorImpl<WriteState *> &Writes,
unsigned RegID) const {
assert(RegID && RegID < RegisterMappings.size());
WriteState *WS = RegisterMappings[RegID].first;
if (WS) {
LLVM_DEBUG(dbgs() << "Found a dependent use of RegID=" << RegID << '\n');
Writes.push_back(WS);
}
// Handle potential partial register updates.
for (MCSubRegIterator I(RegID, &MRI); I.isValid(); ++I) {
WS = RegisterMappings[*I].first;
if (WS && std::find(Writes.begin(), Writes.end(), WS) == Writes.end()) {
LLVM_DEBUG(dbgs() << "Found a dependent use of subReg " << *I
<< " (part of " << RegID << ")\n");
Writes.push_back(WS);
}
}
}
unsigned RegisterFile::isAvailable(ArrayRef<unsigned> Regs) const {
SmallVector<unsigned, 4> NumPhysRegs(getNumRegisterFiles());
// Find how many new mappings must be created for each register file.
for (const unsigned RegID : Regs) {
const IndexPlusCostPairTy &Entry = RegisterMappings[RegID].second;
if (Entry.first)
NumPhysRegs[Entry.first] += Entry.second;
NumPhysRegs[0] += Entry.second;
}
unsigned Response = 0;
for (unsigned I = 0, E = getNumRegisterFiles(); I < E; ++I) {
unsigned NumRegs = NumPhysRegs[I];
if (!NumRegs)
continue;
const RegisterMappingTracker &RMT = RegisterFiles[I];
if (!RMT.TotalMappings) {
// The register file has an unbounded number of microarchitectural
// registers.
continue;
}
if (RMT.TotalMappings < NumRegs) {
// The current register file is too small. This may occur if the number of
// microarchitectural registers in register file #0 was changed by the
// users via flag -reg-file-size. Alternatively, the scheduling model
// specified a too small number of registers for this register file.
report_fatal_error(
"Not enough microarchitectural registers in the register file");
}
if (RMT.TotalMappings < (RMT.NumUsedMappings + NumRegs))
Response |= (1U << I);
}
return Response;
}
#ifndef NDEBUG
void RegisterFile::dump() const {
for (unsigned I = 0, E = MRI.getNumRegs(); I < E; ++I) {
const RegisterMapping &RM = RegisterMappings[I];
dbgs() << MRI.getName(I) << ", " << I << ", Map=" << RM.second.first
<< ", ";
if (RM.first)
RM.first->dump();
else
dbgs() << "(null)\n";
}
for (unsigned I = 0, E = getNumRegisterFiles(); I < E; ++I) {
dbgs() << "Register File #" << I;
const RegisterMappingTracker &RMT = RegisterFiles[I];
dbgs() << "\n TotalMappings: " << RMT.TotalMappings
<< "\n NumUsedMappings: " << RMT.NumUsedMappings << '\n';
}
}
#endif
} // namespace mca