PeepholeOptimizer.cpp File Reference

#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/MachineBasicBlock.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/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetOpcodes.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/InitializePasses.h"
#include "llvm/MC/LaneBitmask.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>
#include <memory>
#include <utility>

Include dependency graph for PeepholeOptimizer.cpp:

Go to the source code of this file.

Macros
#define	DEBUG_TYPE   "peephole-opt"

Typedefs
using	RegSubRegPair = TargetInstrInfo::RegSubRegPair
using	RegSubRegPairAndIdx = TargetInstrInfo::RegSubRegPairAndIdx

Functions
	STATISTIC (NumReuse, "Number of extension results reused")
	STATISTIC (NumCmps, "Number of compares eliminated")
	STATISTIC (NumImmFold, "Number of move immediate folded")
	STATISTIC (NumLoadFold, "Number of loads folded")
	STATISTIC (NumSelects, "Number of selects optimized")
	STATISTIC (NumUncoalescableCopies, "Number of uncoalescable copies optimized")
	STATISTIC (NumRewrittenCopies, "Number of copies rewritten")
	STATISTIC (NumNAPhysCopies, "Number of non-allocatable physical copies removed")
	INITIALIZE_PASS_BEGIN (PeepholeOptimizer, DEBUG_TYPE, "Peephole Optimizations", false, false) INITIALIZE_PASS_END(PeepholeOptimizer
static MachineInstr &	insertPHI (MachineRegisterInfo &MRI, const TargetInstrInfo &TII, const SmallVectorImpl< RegSubRegPair > &SrcRegs, MachineInstr &OrigPHI)
	Insert a PHI instruction with incoming edges SrcRegs that are guaranteed to have the same register class. More...
static Rewriter *	getCopyRewriter (MachineInstr &MI, const TargetInstrInfo &TII)
	Get the appropriated Rewriter for MI. More...
static RegSubRegPair	getNewSource (MachineRegisterInfo *MRI, const TargetInstrInfo *TII, RegSubRegPair Def, const PeepholeOptimizer::RewriteMapTy &RewriteMap, bool HandleMultipleSources=true)
	Given a Def.Reg and Def.SubReg pair, use RewriteMap to find the new source to use for rewrite. More...
static bool	isVirtualRegisterOperand (MachineOperand &MO)
	\bried Returns true if MO is a virtual register operand. More...

Variables
static cl::opt< bool >	Aggressive ("aggressive-ext-opt", cl::Hidden, cl::desc("Aggressive extension optimization"))
static cl::opt< bool >	DisablePeephole ("disable-peephole", cl::Hidden, cl::init(false), cl::desc("Disable the peephole optimizer"))
static cl::opt< bool >	DisableAdvCopyOpt ("disable-adv-copy-opt", cl::Hidden, cl::init(false), cl::desc("Disable advanced copy optimization"))
	Specifiy whether or not the value tracking looks through complex instructions. More...
static cl::opt< bool >	DisableNAPhysCopyOpt ("disable-non-allocatable-phys-copy-opt", cl::Hidden, cl::init(false), cl::desc("Disable non-allocatable physical register copy optimization"))
static cl::opt< unsigned >	RewritePHILimit ("rewrite-phi-limit", cl::Hidden, cl::init(10), cl::desc("Limit the length of PHI chains to lookup"))
static cl::opt< unsigned >	MaxRecurrenceChain ("recurrence-chain-limit", cl::Hidden, cl::init(3), cl::desc("Maximum length of recurrence chain when evaluating the benefit " "of commuting operands"))
	DEBUG_TYPE
Peephole	Optimizations
Peephole	false

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "peephole-opt"

Definition at line 104 of file PeepholeOptimizer.cpp.

Typedef Documentation

RegSubRegPair

using RegSubRegPair = TargetInstrInfo::RegSubRegPair

Definition at line 101 of file PeepholeOptimizer.cpp.

RegSubRegPairAndIdx

using RegSubRegPairAndIdx = TargetInstrInfo::RegSubRegPairAndIdx

Definition at line 102 of file PeepholeOptimizer.cpp.

Function Documentation

getCopyRewriter()

static Rewriter* getCopyRewriter ( MachineInstr &  MI, const TargetInstrInfo &  TII  )

static

Get the appropriated Rewriter for MI.

Returns

A pointer to a dynamically allocated Rewriter or nullptr if no rewriter works for MI.

Definition at line 1105 of file PeepholeOptimizer.cpp.

References MI, and TII.

getNewSource()

static RegSubRegPair getNewSource ( MachineRegisterInfo *  MRI, const TargetInstrInfo *  TII, RegSubRegPair  Def, const PeepholeOptimizer::RewriteMapTy &  RewriteMap, bool  HandleMultipleSources = true  )

static

Given a Def.Reg and Def.SubReg pair, use RewriteMap to find the new source to use for rewrite.

If HandleMultipleSources is true and multiple sources for a given Def are found along the way, we found a PHI instructions that needs to be rewritten. TODO: HandleMultipleSources should be removed once we test PHI handling with coalescable copies.

Definition at line 1132 of file PeepholeOptimizer.cpp.

References llvm::dbgs(), llvm::tgtok::Def, llvm::MachineInstr::getOperand(), llvm::MachineOperand::getReg(), llvm::MachineOperand::getSubReg(), i, insertPHI(), LLVM_DEBUG, llvm::DenseMapBase< DerivedT, KeyT, ValueT, KeyInfoT, BucketT >::lookup(), MRI, llvm::TargetInstrInfo::RegSubRegPair::Reg, llvm::TargetInstrInfo::RegSubRegPair::SubReg, and TII.

INITIALIZE_PASS_BEGIN()

INITIALIZE_PASS_BEGIN	(	PeepholeOptimizer	,
		DEBUG_TYPE	,
		"Peephole Optimizations"	,
		false	,
		false
	)

insertPHI()

static MachineInstr& insertPHI ( MachineRegisterInfo &  MRI, const TargetInstrInfo &  TII, const SmallVectorImpl< RegSubRegPair > &  SrcRegs, MachineInstr &  OrigPHI  )

static

Insert a PHI instruction with incoming edges SrcRegs that are guaranteed to have the same register class.

This is necessary whenever we successfully traverse a PHI instruction and find suitable sources coming from its edges. By inserting a new PHI, we provide a rewritten PHI def suitable to be used in a new COPY instruction.

Definition at line 776 of file PeepholeOptimizer.cpp.

References llvm::MachineInstrBuilder::addMBB(), llvm::MachineInstrBuilder::addReg(), assert(), llvm::BuildMI(), llvm::MachineRegisterInfo::clearKillFlags(), llvm::MachineRegisterInfo::createVirtualRegister(), llvm::MachineInstr::getDebugLoc(), llvm::MachineOperand::getMBB(), llvm::MachineInstr::getOperand(), llvm::MachineInstr::getParent(), llvm::MachineRegisterInfo::getRegClass(), MBB, MRI, Reg, SubReg, and TII.

Referenced by getNewSource().

isVirtualRegisterOperand()

static bool isVirtualRegisterOperand ( MachineOperand &  MO )

static

\bried Returns true if MO is a virtual register operand.

Definition at line 1503 of file PeepholeOptimizer.cpp.

References llvm::MachineOperand::getReg(), llvm::MachineOperand::isReg(), and llvm::Register::isVirtual().

STATISTIC() [1/8]

STATISTIC	(	NumCmps	,
		"Number of compares eliminated"
	)

STATISTIC() [2/8]

STATISTIC	(	NumImmFold	,
		"Number of move immediate folded"
	)

STATISTIC() [3/8]

STATISTIC	(	NumLoadFold	,
		"Number of loads folded"
	)

STATISTIC() [4/8]

STATISTIC	(	NumNAPhysCopies	,
		"Number of non-allocatable physical copies removed"
	)

STATISTIC() [5/8]

STATISTIC	(	NumReuse	,
		"Number of extension results reused"
	)

STATISTIC() [6/8]

STATISTIC	(	NumRewrittenCopies	,
		"Number of copies rewritten"
	)

STATISTIC() [7/8]

STATISTIC	(	NumSelects	,
		"Number of selects optimized"
	)

STATISTIC() [8/8]

STATISTIC	(	NumUncoalescableCopies	,
		"Number of uncoalescable copies optimized"
	)

Variable Documentation

Aggressive

cl::opt<bool> Aggressive("aggressive-ext-opt", cl::Hidden, cl::desc("Aggressive extension optimization"))

static

DEBUG_TYPE

DEBUG_TYPE

Definition at line 449 of file PeepholeOptimizer.cpp.

DisableAdvCopyOpt

cl::opt<bool> DisableAdvCopyOpt("disable-adv-copy-opt", cl::Hidden, cl::init(false), cl::desc("Disable advanced copy optimization"))

static

Specifiy whether or not the value tracking looks through complex instructions.

When this is true, the value tracker bails on everything that is not a copy or a bitcast.

DisableNAPhysCopyOpt

cl::opt<bool> DisableNAPhysCopyOpt("disable-non-allocatable-phys-copy-opt", cl::Hidden, cl::init(false), cl::desc("Disable non-allocatable physical register copy optimization"))

static

DisablePeephole

cl::opt<bool> DisablePeephole("disable-peephole", cl::Hidden, cl::init(false), cl::desc("Disable the peephole optimizer"))

static

false

Peephole false

Definition at line 450 of file PeepholeOptimizer.cpp.

MaxRecurrenceChain

cl::opt<unsigned> MaxRecurrenceChain("recurrence-chain-limit", cl::Hidden, cl::init(3), cl::desc("Maximum length of recurrence chain when evaluating the benefit " "of commuting operands"))

static

Optimizations

Peephole Optimizations

Definition at line 450 of file PeepholeOptimizer.cpp.

RewritePHILimit

cl::opt<unsigned> RewritePHILimit("rewrite-phi-limit", cl::Hidden, cl::init(10), cl::desc("Limit the length of PHI chains to lookup"))

static