class CriticalAntiDepBreaker

Declaration

class CriticalAntiDepBreaker : public AntiDepBreaker { /* full declaration omitted */ };

Description

This class works in conjunction with the post-RA scheduler to rename registers to break register anti-dependencies (WAR hazards).

Declared at: llvm/lib/CodeGen/CriticalAntiDepBreaker.h:36

Inherits from: AntiDepBreaker

Member Variables

private llvm::MachineFunction& MF

private llvm::MachineRegisterInfo& MRI

private const llvm::TargetInstrInfo* TII

private const llvm::TargetRegisterInfo* TRI

private const llvm::RegisterClassInfo& RegClassInfo

private const llvm::BitVector AllocatableSet

The set of allocatable registers. We'll be ignoring anti-dependencies on non-allocatable registers, because they may not be safe to break.

private std::vector<const TargetRegisterClass*> Classes

For live regs that are only used in one register class in a live range, the register class. If the register is not live, the corresponding value is null. If the register is live but used in multiple register classes, the corresponding value is -1 casted to a pointer.

private std::multimap<unsigned int, MachineOperand*> RegRefs

Map registers to all their references within a live range.

private std::vector<unsigned int> KillIndices

The index of the most recent kill (proceeding bottom-up), or ~0u if the register is not live.

private std::vector<unsigned int> DefIndices

The index of the most recent complete def (proceeding bottom up), or ~0u if the register is live.

private llvm::BitVector KeepRegs

A set of registers which are live and cannot be changed to break anti-dependencies.

Method Overview

• public unsigned int BreakAntiDependencies(const std::vector<SUnit> & SUnits, MachineBasicBlock::iterator Begin, MachineBasicBlock::iterator End, unsigned int InsertPosIndex, llvm::AntiDepBreaker::DbgValueVector & DbgValues)
• public CriticalAntiDepBreaker(llvm::MachineFunction & MFi, const llvm::RegisterClassInfo & RCI)
• public void FinishBlock()
• public void Observe(llvm::MachineInstr & MI, unsigned int Count, unsigned int InsertPosIndex)
• private void PrescanInstruction(llvm::MachineInstr & MI)
• private void ScanInstruction(llvm::MachineInstr & MI, unsigned int Count)
• public void StartBlock(llvm::MachineBasicBlock * BB)
• private unsigned int findSuitableFreeRegister(llvm::CriticalAntiDepBreaker::RegRefIter RegRefBegin, llvm::CriticalAntiDepBreaker::RegRefIter RegRefEnd, unsigned int AntiDepReg, unsigned int LastNewReg, const llvm::TargetRegisterClass * RC, SmallVectorImpl<unsigned int> & Forbid)
• private bool isNewRegClobberedByRefs(llvm::CriticalAntiDepBreaker::RegRefIter RegRefBegin, llvm::CriticalAntiDepBreaker::RegRefIter RegRefEnd, unsigned int NewReg)
• public ~CriticalAntiDepBreaker()

Inherited from AntiDepBreaker:

• public BreakAntiDependencies
• public FinishBlock
• public Observe
• public StartBlock
• public UpdateDbgValue
• public UpdateDbgValues

Methods

¶unsigned int BreakAntiDependencies(
    const std::vector<SUnit>& SUnits,
    MachineBasicBlock::iterator Begin,
    MachineBasicBlock::iterator End,
    unsigned int InsertPosIndex,
    llvm::AntiDepBreaker::DbgValueVector&
        DbgValues)

Description

Identifiy anti-dependencies along the critical path of the ScheduleDAG and break them by renaming registers.

Declared at: llvm/lib/CodeGen/CriticalAntiDepBreaker.h:82

Parameters

const std::vector<SUnit>& SUnits

MachineBasicBlock::iterator Begin

MachineBasicBlock::iterator End

unsigned int InsertPosIndex

llvm::AntiDepBreaker::DbgValueVector& DbgValues

¶CriticalAntiDepBreaker(
    llvm::MachineFunction& MFi,
    const llvm::RegisterClassInfo& RCI)

Declared at: llvm/lib/CodeGen/CriticalAntiDepBreaker.h:74

Parameters

llvm::MachineFunction& MFi

const llvm::RegisterClassInfo& RCI

¶void FinishBlock()

Description

Finish anti-dep breaking for a basic block.

Declared at: llvm/lib/CodeGen/CriticalAntiDepBreaker.h:94

¶void Observe(llvm::MachineInstr& MI,
             unsigned int Count,
             unsigned int InsertPosIndex)

Description

Update liveness information to account for the current instruction, which will not be scheduled.

Declared at: llvm/lib/CodeGen/CriticalAntiDepBreaker.h:90

Parameters

llvm::MachineInstr& MI

unsigned int Count

unsigned int InsertPosIndex

¶void PrescanInstruction(llvm::MachineInstr& MI)

Declared at: llvm/lib/CodeGen/CriticalAntiDepBreaker.h:97

Parameters

llvm::MachineInstr& MI

¶void ScanInstruction(llvm::MachineInstr& MI,
                     unsigned int Count)

Declared at: llvm/lib/CodeGen/CriticalAntiDepBreaker.h:98

Parameters

llvm::MachineInstr& MI

unsigned int Count

¶void StartBlock(llvm::MachineBasicBlock* BB)

Description

Initialize anti-dep breaking for a new basic block.

Declared at: llvm/lib/CodeGen/CriticalAntiDepBreaker.h:78

Parameters

llvm::MachineBasicBlock* BB

¶unsigned int findSuitableFreeRegister(
    llvm::CriticalAntiDepBreaker::RegRefIter
        RegRefBegin,
    llvm::CriticalAntiDepBreaker::RegRefIter
        RegRefEnd,
    unsigned int AntiDepReg,
    unsigned int LastNewReg,
    const llvm::TargetRegisterClass* RC,
    SmallVectorImpl<unsigned int>& Forbid)

Declared at: llvm/lib/CodeGen/CriticalAntiDepBreaker.h:102

Parameters

llvm::CriticalAntiDepBreaker::RegRefIter RegRefBegin

llvm::CriticalAntiDepBreaker::RegRefIter RegRefEnd

unsigned int AntiDepReg

unsigned int LastNewReg

const llvm::TargetRegisterClass* RC

SmallVectorImpl<unsigned int>& Forbid

¶bool isNewRegClobberedByRefs(
    llvm::CriticalAntiDepBreaker::RegRefIter
        RegRefBegin,
    llvm::CriticalAntiDepBreaker::RegRefIter
        RegRefEnd,
    unsigned int NewReg)

Declared at: llvm/lib/CodeGen/CriticalAntiDepBreaker.h:99

Parameters

llvm::CriticalAntiDepBreaker::RegRefIter RegRefBegin

llvm::CriticalAntiDepBreaker::RegRefIter RegRefEnd

unsigned int NewReg

¶~CriticalAntiDepBreaker()

Declared at: llvm/lib/CodeGen/CriticalAntiDepBreaker.h:75