LICM.cpp File Reference

#include "llvm/Transforms/Scalar/LICM.h"
#include "llvm/ADT/PriorityWorklist.h"
#include "llvm/ADT/SetOperations.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/AliasSetTracker.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/CaptureTracking.h"
#include "llvm/Analysis/DomTreeUpdater.h"
#include "llvm/Analysis/GuardUtils.h"
#include "llvm/Analysis/LazyBlockFrequencyInfo.h"
#include "llvm/Analysis/Loads.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/LoopIterator.h"
#include "llvm/Analysis/LoopNestAnalysis.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/MemorySSA.h"
#include "llvm/Analysis/MemorySSAUpdater.h"
#include "llvm/Analysis/MustExecute.h"
#include "llvm/Analysis/OptimizationRemarkEmitter.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/IR/PredIteratorCache.h"
#include "llvm/InitializePasses.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/AssumeBundleBuilder.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/LoopUtils.h"
#include "llvm/Transforms/Utils/SSAUpdater.h"
#include <algorithm>
#include <utility>

Go to the source code of this file.

Namespaces
namespace	llvm
	This is an optimization pass for GlobalISel generic memory operations.

Macros
#define	DEBUG_TYPE   "licm"

Typedefs
using	PointersAndHasReadsOutsideSet = std::pair< SmallSetVector< Value *, 8 >, bool >

Functions
	STATISTIC (NumCreatedBlocks, "Number of blocks created")
	STATISTIC (NumClonedBranches, "Number of branches cloned")
	STATISTIC (NumSunk, "Number of instructions sunk out of loop")
	STATISTIC (NumHoisted, "Number of instructions hoisted out of loop")
	STATISTIC (NumMovedLoads, "Number of load insts hoisted or sunk")
	STATISTIC (NumMovedCalls, "Number of call insts hoisted or sunk")
	STATISTIC (NumPromotionCandidates, "Number of promotion candidates")
	STATISTIC (NumLoadPromoted, "Number of load-only promotions")
	STATISTIC (NumLoadStorePromoted, "Number of load and store promotions")
	STATISTIC (NumMinMaxHoisted, "Number of min/max expressions hoisted out of the loop")
	STATISTIC (NumGEPsHoisted, "Number of geps reassociated and hoisted out of the loop")
	STATISTIC (NumAddSubHoisted, "Number of add/subtract expressions reassociated " "and hoisted out of the loop")
	STATISTIC (NumFPAssociationsHoisted, "Number of invariant FP expressions " "reassociated and hoisted out of the loop")
	STATISTIC (NumIntAssociationsHoisted, "Number of invariant int expressions " "reassociated and hoisted out of the loop")
	STATISTIC (NumBOAssociationsHoisted, "Number of invariant BinaryOp expressions " "reassociated and hoisted out of the loop")
static bool	inSubLoop (BasicBlock *BB, Loop *CurLoop, LoopInfo *LI)
	Little predicate that returns true if the specified basic block is in a subloop of the current one, not the current one itself.
static bool	isNotUsedOrFoldableInLoop (const Instruction &I, const Loop *CurLoop, const LoopSafetyInfo *SafetyInfo, TargetTransformInfo *TTI, bool &FoldableInLoop, bool LoopNestMode)
	Return true if the only users of this instruction are outside of the loop.
static void	hoist (Instruction &I, const DominatorTree *DT, const Loop *CurLoop, BasicBlock *Dest, ICFLoopSafetyInfo *SafetyInfo, MemorySSAUpdater &MSSAU, ScalarEvolution *SE, OptimizationRemarkEmitter *ORE)
	When an instruction is found to only use loop invariant operands that is safe to hoist, this instruction is called to do the dirty work.
static bool	sink (Instruction &I, LoopInfo *LI, DominatorTree *DT, const Loop *CurLoop, ICFLoopSafetyInfo *SafetyInfo, MemorySSAUpdater &MSSAU, OptimizationRemarkEmitter *ORE)
	When an instruction is found to only be used outside of the loop, this function moves it to the exit blocks and patches up SSA form as needed.
static bool	isSafeToExecuteUnconditionally (Instruction &Inst, const DominatorTree *DT, const TargetLibraryInfo *TLI, const Loop *CurLoop, const LoopSafetyInfo *SafetyInfo, OptimizationRemarkEmitter *ORE, const Instruction *CtxI, AssumptionCache *AC, bool AllowSpeculation)
	Only sink or hoist an instruction if it is not a trapping instruction, or if the instruction is known not to trap when moved to the preheader.
static bool	pointerInvalidatedByLoop (MemorySSA *MSSA, MemoryUse *MU, Loop *CurLoop, Instruction &I, SinkAndHoistLICMFlags &Flags, bool InvariantGroup)
static bool	pointerInvalidatedByBlock (BasicBlock &BB, MemorySSA &MSSA, MemoryUse &MU)
static bool	hoistArithmetics (Instruction &I, Loop &L, ICFLoopSafetyInfo &SafetyInfo, MemorySSAUpdater &MSSAU, AssumptionCache *AC, DominatorTree *DT)
	Aggregates various functions for hoisting computations out of loop.
static Instruction *	cloneInstructionInExitBlock (Instruction &I, BasicBlock &ExitBlock, PHINode &PN, const LoopInfo *LI, const LoopSafetyInfo *SafetyInfo, MemorySSAUpdater &MSSAU)
static void	eraseInstruction (Instruction &I, ICFLoopSafetyInfo &SafetyInfo, MemorySSAUpdater &MSSAU)
static void	moveInstructionBefore (Instruction &I, BasicBlock::iterator Dest, ICFLoopSafetyInfo &SafetyInfo, MemorySSAUpdater &MSSAU, ScalarEvolution *SE)
static void	foreachMemoryAccess (MemorySSA *MSSA, Loop *L, function_ref< void(Instruction *)> Fn)
static SmallVector< PointersAndHasReadsOutsideSet, 0 >	collectPromotionCandidates (MemorySSA *MSSA, AliasAnalysis *AA, Loop *L)
	INITIALIZE_PASS_BEGIN (LegacyLICMPass, "licm", "Loop Invariant Code Motion", false, false) INITIALIZE_PASS_END(LegacyLICMPass
static bool	isLoadInvariantInLoop (LoadInst *LI, DominatorTree *DT, Loop *CurLoop)
static MemoryAccess *	getClobberingMemoryAccess (MemorySSA &MSSA, BatchAAResults &BAA, SinkAndHoistLICMFlags &Flags, MemoryUseOrDef *MA)
static bool	isTriviallyReplaceablePHI (const PHINode &PN, const Instruction &I)
	Returns true if a PHINode is a trivially replaceable with an Instruction.
static bool	isFoldableInLoop (const Instruction &I, const Loop *CurLoop, const TargetTransformInfo *TTI)
	Return true if the instruction is foldable in the loop.
static Instruction *	sinkThroughTriviallyReplaceablePHI (PHINode *TPN, Instruction *I, LoopInfo *LI, SmallDenseMap< BasicBlock *, Instruction *, 32 > &SunkCopies, const LoopSafetyInfo *SafetyInfo, const Loop *CurLoop, MemorySSAUpdater &MSSAU)
static bool	canSplitPredecessors (PHINode *PN, LoopSafetyInfo *SafetyInfo)
static void	splitPredecessorsOfLoopExit (PHINode *PN, DominatorTree *DT, LoopInfo *LI, const Loop *CurLoop, LoopSafetyInfo *SafetyInfo, MemorySSAUpdater *MSSAU)
static bool	hoistMinMax (Instruction &I, Loop &L, ICFLoopSafetyInfo &SafetyInfo, MemorySSAUpdater &MSSAU)
	Try to simplify things like (A < INV_1 AND icmp A < INV_2) into (A < min(INV_1, INV_2)), if INV_1 and INV_2 are both loop invariants and their minimun can be computed outside of loop, and X is not a loop-invariant.
static bool	hoistGEP (Instruction &I, Loop &L, ICFLoopSafetyInfo &SafetyInfo, MemorySSAUpdater &MSSAU, AssumptionCache *AC, DominatorTree *DT)
	Reassociate gep (gep ptr, idx1), idx2 to gep (gep ptr, idx2), idx1 if this allows hoisting the inner GEP.
static bool	hoistAdd (ICmpInst::Predicate Pred, Value *VariantLHS, Value *InvariantRHS, ICmpInst &ICmp, Loop &L, ICFLoopSafetyInfo &SafetyInfo, MemorySSAUpdater &MSSAU, AssumptionCache *AC, DominatorTree *DT)
	Try to turn things like "LV + C1 < C2" into "LV < C2 - C1".
static bool	hoistSub (ICmpInst::Predicate Pred, Value *VariantLHS, Value *InvariantRHS, ICmpInst &ICmp, Loop &L, ICFLoopSafetyInfo &SafetyInfo, MemorySSAUpdater &MSSAU, AssumptionCache *AC, DominatorTree *DT)
	Try to reassociate and hoist the following two patterns: LV - C1 < C2 --> LV < C1 + C2, C1 - LV < C2 --> LV > C1 - C2.
static bool	hoistAddSub (Instruction &I, Loop &L, ICFLoopSafetyInfo &SafetyInfo, MemorySSAUpdater &MSSAU, AssumptionCache *AC, DominatorTree *DT)
	Reassociate and hoist add/sub expressions.
static bool	isReassociableOp (Instruction *I, unsigned IntOpcode, unsigned FPOpcode)
static bool	hoistMulAddAssociation (Instruction &I, Loop &L, ICFLoopSafetyInfo &SafetyInfo, MemorySSAUpdater &MSSAU, AssumptionCache *AC, DominatorTree *DT)
	Try to reassociate expressions like ((A1 * B1) + (A2 * B2) + ...) * C where A1, A2, ... and C are loop invariants into expressions like ((A1 * C * B1) + (A2 * C * B2) + ...) and hoist the (A1 * C), (A2 * C), ... invariant expressions.
static bool	hoistBOAssociation (Instruction &I, Loop &L, ICFLoopSafetyInfo &SafetyInfo, MemorySSAUpdater &MSSAU, AssumptionCache *AC, DominatorTree *DT)
	Reassociate associative binary expressions of the form.

Variables
static cl::opt< bool >	DisablePromotion ("disable-licm-promotion", cl::Hidden, cl::init(false), cl::desc("Disable memory promotion in LICM pass"))
	Memory promotion is enabled by default.
static cl::opt< bool >	ControlFlowHoisting ("licm-control-flow-hoisting", cl::Hidden, cl::init(false), cl::desc("Enable control flow (and PHI) hoisting in LICM"))
static cl::opt< bool >	SingleThread ("licm-force-thread-model-single", cl::Hidden, cl::init(false), cl::desc("Force thread model single in LICM pass"))
static cl::opt< uint32_t >	MaxNumUsesTraversed ("licm-max-num-uses-traversed", cl::Hidden, cl::init(8), cl::desc("Max num uses visited for identifying load " "invariance in loop using invariant start (default = 8)"))
static cl::opt< unsigned >	FPAssociationUpperLimit ("licm-max-num-fp-reassociations", cl::init(5U), cl::Hidden, cl::desc("Set upper limit for the number of transformations performed " "during a single round of hoisting the reassociated expressions."))
cl::opt< unsigned >	IntAssociationUpperLimit ("licm-max-num-int-reassociations", cl::init(5U), cl::Hidden, cl::desc("Set upper limit for the number of transformations performed " "during a single round of hoisting the reassociated expressions."))
	licm
Loop Invariant Code	Motion
Loop Invariant Code	false

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "licm"

Definition at line 94 of file LICM.cpp.

Typedef Documentation

PointersAndHasReadsOutsideSet

using PointersAndHasReadsOutsideSet = std::pair<SmallSetVector<Value *, 8>, bool>

Definition at line 213 of file LICM.cpp.

Function Documentation

canSplitPredecessors()

static bool canSplitPredecessors ( PHINode *  PN, LoopSafetyInfo *  SafetyInfo  )

static

Definition at line 1544 of file LICM.cpp.

References llvm::BasicBlock::canSplitPredecessors(), llvm::LoopSafetyInfo::getBlockColors(), llvm::BasicBlock::getFirstNonPHI(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::Instruction::isEHPad(), and llvm::predecessors().

Referenced by sink().

cloneInstructionInExitBlock()

static Instruction * cloneInstructionInExitBlock ( Instruction &  I, BasicBlock &  ExitBlock, PHINode &  PN, const LoopInfo *  LI, const LoopSafetyInfo *  SafetyInfo, MemorySSAUpdater &  MSSAU  )

static

Definition at line 1427 of file LICM.cpp.

References llvm::PHINode::addIncoming(), assert(), llvm::BasicBlock::begin(), llvm::MemorySSA::Beginning, llvm::CallInst::Create(), llvm::PHINode::Create(), llvm::MemorySSAUpdater::createMemoryAccessInBB(), llvm::SmallVectorImpl< T >::emplace_back(), llvm::TinyPtrVector< EltTy >::front(), llvm::LoopSafetyInfo::getBlockColors(), llvm::BasicBlock::getFirstInsertionPt(), llvm::BasicBlock::getFirstNonPHI(), llvm::PHINode::getIncomingBlock(), llvm::MemorySSA::getMemoryAccess(), llvm::MemorySSAUpdater::getMemorySSA(), llvm::PHINode::getNumIncomingValues(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::OperandBundleUse::getTagID(), I, llvm::Instruction::insertBefore(), llvm::MemorySSAUpdater::insertDef(), llvm::MemorySSAUpdater::insertUse(), llvm::Instruction::isEHPad(), llvm::LLVMContext::OB_funclet, llvm::TinyPtrVector< EltTy >::size(), and llvm::LoopInfo::wouldBeOutOfLoopUseRequiringLCSSA().

Referenced by sinkThroughTriviallyReplaceablePHI().

collectPromotionCandidates()

static SmallVector< PointersAndHasReadsOutsideSet, 0 > collectPromotionCandidates ( MemorySSA *  MSSA, AliasAnalysis *  AA, Loop *  L  )

static

Definition at line 2296 of file LICM.cpp.

References llvm::AliasSetTracker::add(), llvm::SmallPtrSetImpl< PtrType >::contains(), llvm::erase_if(), foreachMemoryAccess(), I, llvm::SmallPtrSetImpl< PtrType >::insert(), and llvm::SmallVectorTemplateBase< T, bool >::push_back().

eraseInstruction()

static void eraseInstruction ( Instruction &  I, ICFLoopSafetyInfo &  SafetyInfo, MemorySSAUpdater &  MSSAU  )

static

Definition at line 1504 of file LICM.cpp.

References I, llvm::ICFLoopSafetyInfo::removeInstruction(), and llvm::MemorySSAUpdater::removeMemoryAccess().

Referenced by hoistAdd(), hoistBOAssociation(), hoistGEP(), hoistMinMax(), hoistMulAddAssociation(), llvm::hoistRegion(), hoistSub(), llvm::promoteLoopAccessesToScalars(), sink(), and llvm::sinkRegion().

foreachMemoryAccess()

static void foreachMemoryAccess ( MemorySSA *  MSSA, Loop *  L, function_ref< void(Instruction *)>  Fn  )

static

Definition at line 2284 of file LICM.cpp.

References Access, and llvm::MemorySSA::getBlockAccesses().

Referenced by collectPromotionCandidates().

getClobberingMemoryAccess()

static MemoryAccess * getClobberingMemoryAccess ( MemorySSA &  MSSA, BatchAAResults &  BAA, SinkAndHoistLICMFlags &  Flags, MemoryUseOrDef *  MA  )

static

Definition at line 1147 of file LICM.cpp.

References llvm::MemorySSAWalker::getClobberingMemoryAccess(), llvm::MemoryUseOrDef::getDefiningAccess(), and llvm::MemorySSA::getSkipSelfWalker().

Referenced by llvm::canSinkOrHoistInst(), and pointerInvalidatedByLoop().

hoist()

static void hoist ( Instruction &  I, const DominatorTree *  DT, const Loop *  CurLoop, BasicBlock *  Dest, ICFLoopSafetyInfo *  SafetyInfo, MemorySSAUpdater &  MSSAU, ScalarEvolution *  SE, OptimizationRemarkEmitter *  ORE  )

static

When an instruction is found to only use loop invariant operands that is safe to hoist, this instruction is called to do the dirty work.

Definition at line 1741 of file LICM.cpp.

References llvm::dbgs(), DEBUG_TYPE, llvm::OptimizationRemarkEmitter::emit(), llvm::BasicBlock::getFirstNonPHIIt(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::Value::getNameOrAsOperand(), llvm::BasicBlock::getTerminator(), I, llvm::ICFLoopSafetyInfo::isGuaranteedToExecute(), LLVM_DEBUG, and moveInstructionBefore().

Referenced by llvm::hoistRegion().

hoistAdd()

static bool hoistAdd ( ICmpInst::Predicate  Pred, Value *  VariantLHS, Value *  InvariantRHS, ICmpInst &  ICmp, Loop &  L, ICFLoopSafetyInfo &  SafetyInfo, MemorySSAUpdater &  MSSAU, AssumptionCache *  AC, DominatorTree *  DT  )

static

Try to turn things like "LV + C1 < C2" into "LV < C2 - C1".

Here C1 and C2 are loop invariants and LV is a loop-variant.

Definition at line 2549 of file LICM.cpp.

References assert(), llvm::computeOverflowForSignedSub(), llvm::computeOverflowForUnsignedSub(), llvm::IRBuilderBase::CreateSub(), DL, eraseInstruction(), llvm::BasicBlock::getTerminator(), llvm::CmpInst::isSigned(), llvm::PatternMatch::m_NSWAdd(), llvm::PatternMatch::m_NUWAdd(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), llvm::NeverOverflows, llvm::User::setOperand(), llvm::CmpInst::setPredicate(), and std::swap().

Referenced by hoistAddSub().

hoistAddSub()

static bool hoistAddSub ( Instruction &  I, Loop &  L, ICFLoopSafetyInfo &  SafetyInfo, MemorySSAUpdater &  MSSAU, AssumptionCache *  AC, DominatorTree *  DT  )

static

Reassociate and hoist add/sub expressions.

Definition at line 2680 of file LICM.cpp.

References llvm::CmpInst::getSwappedPredicate(), llvm::Value::hasOneUse(), hoistAdd(), hoistSub(), I, LHS, llvm::PatternMatch::m_ICmp(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), RHS, and std::swap().

Referenced by hoistArithmetics().

hoistArithmetics()

static bool hoistArithmetics ( Instruction &  I, Loop &  L, ICFLoopSafetyInfo &  SafetyInfo, MemorySSAUpdater &  MSSAU, AssumptionCache *  AC, DominatorTree *  DT  )

static

Aggregates various functions for hoisting computations out of loop.

Definition at line 2888 of file LICM.cpp.

References hoistAddSub(), hoistBOAssociation(), hoistGEP(), hoistMinMax(), hoistMulAddAssociation(), and I.

Referenced by llvm::hoistRegion().

hoistBOAssociation()

static bool hoistBOAssociation ( Instruction &  I, Loop &  L, ICFLoopSafetyInfo &  SafetyInfo, MemorySSAUpdater &  MSSAU, AssumptionCache *  AC, DominatorTree *  DT  )

static

Reassociate associative binary expressions of the form.

1. "(LV op C1) op C2" ==> "LV op (C1 op C2)"
2. "(C1 op LV) op C2" ==> "LV op (C1 op C2)"
3. "C2 op (C1 op LV)" ==> "LV op (C1 op C2)"
4. "C2 op (LV op C1)" ==> "LV op (C1 op C2)"

where op is an associative BinOp, LV is a loop variant, and C1 and C2 are loop invariants that we want to hoist, noting that associativity implies commutativity.

Definition at line 2827 of file LICM.cpp.

References assert(), llvm::BinaryOperator::Create(), llvm::IRBuilderBase::CreateBinOp(), eraseInstruction(), llvm::Value::getName(), llvm::BasicBlock::getTerminator(), I, and std::swap().

Referenced by hoistArithmetics().

hoistGEP()

static bool hoistGEP ( Instruction &  I, Loop &  L, ICFLoopSafetyInfo &  SafetyInfo, MemorySSAUpdater &  MSSAU, AssumptionCache *  AC, DominatorTree *  DT  )

static

Reassociate gep (gep ptr, idx1), idx2 to gep (gep ptr, idx2), idx1 if this allows hoisting the inner GEP.

Definition at line 2498 of file LICM.cpp.

References llvm::all_of(), llvm::IRBuilderBase::CreateGEP(), DL, eraseInstruction(), GEP, llvm::BasicBlock::getTerminator(), I, llvm::isKnownNonNegative(), NonNegative, and llvm::IRBuilderBase::SetInsertPoint().

Referenced by hoistArithmetics().

hoistMinMax()

static bool hoistMinMax ( Instruction &  I, Loop &  L, ICFLoopSafetyInfo &  SafetyInfo, MemorySSAUpdater &  MSSAU  )

static

Try to simplify things like (A < INV_1 AND icmp A < INV_2) into (A < min(INV_1, INV_2)), if INV_1 and INV_2 are both loop invariants and their minimun can be computed outside of loop, and X is not a loop-invariant.

Definition at line 2421 of file LICM.cpp.

References assert(), llvm::CallingConv::C, llvm::IRBuilderBase::CreateBinaryIntrinsic(), llvm::IRBuilderBase::CreateFreeze(), llvm::IRBuilderBase::CreateICmp(), eraseInstruction(), llvm::CmpInst::getInversePredicate(), llvm::CmpPredicate::getMatching(), llvm::Value::getName(), llvm::CmpInst::getSwappedPredicate(), llvm::BasicBlock::getTerminator(), llvm::Value::getType(), I, llvm::ICmpInst::isGE(), llvm::ICmpInst::isGT(), llvm::Type::isIntegerTy(), llvm::ICmpInst::isLE(), llvm::ICmpInst::isLT(), llvm::ICmpInst::isRelational(), llvm::CmpInst::isSigned(), LHS, llvm::PatternMatch::m_ICmp(), llvm::PatternMatch::m_LogicalAnd(), llvm::PatternMatch::m_LogicalOr(), llvm::PatternMatch::m_OneUse(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), P, RHS, llvm::IRBuilderBase::SetInsertPoint(), std::swap(), and llvm::Value::takeName().

Referenced by hoistArithmetics().

hoistMulAddAssociation()

static bool hoistMulAddAssociation ( Instruction &  I, Loop &  L, ICFLoopSafetyInfo &  SafetyInfo, MemorySSAUpdater &  MSSAU, AssumptionCache *  AC, DominatorTree *  DT  )

static

Try to reassociate expressions like ((A1 * B1) + (A2 * B2) + ...) * C where A1, A2, ... and C are loop invariants into expressions like ((A1 * C * B1) + (A2 * C * B2) + ...) and hoist the (A1 * C), (A2 * C), ... invariant expressions.

This functions returns true only if any hoisting has actually occured.

Definition at line 2725 of file LICM.cpp.

References llvm::Add, assert(), llvm::BinaryOperator::Create(), llvm::IRBuilderBase::CreateFMulFMF(), llvm::IRBuilderBase::CreateMul(), llvm::SmallVectorBase< Size_T >::empty(), eraseInstruction(), FPAssociationUpperLimit, llvm::User::getOperand(), llvm::User::getOperandUse(), llvm::BasicBlock::getTerminator(), llvm::Value::hasOneUse(), I, IntAssociationUpperLimit, isReassociableOp(), LHS, llvm::Mul, llvm::SmallVectorImpl< T >::pop_back_val(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), RHS, llvm::SmallVectorBase< Size_T >::size(), and std::swap().

Referenced by hoistArithmetics().

hoistSub()

static bool hoistSub ( ICmpInst::Predicate  Pred, Value *  VariantLHS, Value *  InvariantRHS, ICmpInst &  ICmp, Loop &  L, ICFLoopSafetyInfo &  SafetyInfo, MemorySSAUpdater &  MSSAU, AssumptionCache *  AC, DominatorTree *  DT  )

static

Try to reassociate and hoist the following two patterns: LV - C1 < C2 --> LV < C1 + C2, C1 - LV < C2 --> LV > C1 - C2.

Definition at line 2604 of file LICM.cpp.

References assert(), llvm::computeOverflowForSignedAdd(), llvm::computeOverflowForSignedSub(), llvm::computeOverflowForUnsignedAdd(), llvm::computeOverflowForUnsignedSub(), llvm::IRBuilderBase::CreateAdd(), llvm::IRBuilderBase::CreateSub(), DL, eraseInstruction(), llvm::CmpInst::getSwappedPredicate(), llvm::BasicBlock::getTerminator(), llvm::CmpInst::isSigned(), llvm::PatternMatch::m_NSWSub(), llvm::PatternMatch::m_NUWSub(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), llvm::NeverOverflows, llvm::User::setOperand(), llvm::CmpInst::setPredicate(), and std::swap().

Referenced by hoistAddSub().

INITIALIZE_PASS_BEGIN()

INITIALIZE_PASS_BEGIN	(	LegacyLICMPass	,
		"licm"	,
		"Loop Invariant Code Motion"	,
		false	,
		false
	)

inSubLoop()

static bool inSubLoop ( BasicBlock *  BB, Loop *  CurLoop, LoopInfo *  LI  )

static

Little predicate that returns true if the specified basic block is in a subloop of the current one, not the current one itself.

Definition at line 2937 of file LICM.cpp.

References assert(), llvm::LoopBase< BlockT, LoopT >::contains(), and llvm::LoopInfoBase< BlockT, LoopT >::getLoopFor().

Referenced by llvm::hoistRegion(), and llvm::sinkRegion().

isFoldableInLoop()

static bool isFoldableInLoop ( const Instruction &  I, const Loop *  CurLoop, const TargetTransformInfo *  TTI  )

static

Return true if the instruction is foldable in the loop.

Definition at line 1355 of file LICM.cpp.

References llvm::LoopBase< BlockT, LoopT >::contains(), GEP, llvm::TargetTransformInfo::getInstructionCost(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), I, llvm::TargetTransformInfo::TCC_Free, and llvm::TargetTransformInfo::TCK_SizeAndLatency.

Referenced by isNotUsedOrFoldableInLoop().

isLoadInvariantInLoop()

static bool isLoadInvariantInLoop ( LoadInst *  LI, DominatorTree *  DT, Loop *  CurLoop  )

static

Definition at line 1053 of file LICM.cpp.

References Addr, DL, llvm::Instruction::getDataLayout(), llvm::details::FixedOrScalableQuantity< LeafTy, ValueTy >::getFixedValue(), llvm::LoopBase< BlockT, LoopT >::getHeader(), llvm::LoadInst::getPointerOperand(), llvm::ConstantInt::getSExtValue(), llvm::Value::getType(), II, llvm::ConstantInt::isNegative(), llvm::details::FixedOrScalableQuantity< LeafTy, ValueTy >::isScalable(), MaxNumUsesTraversed, and llvm::DominatorTreeBase< NodeT, IsPostDom >::properlyDominates().

Referenced by llvm::canSinkOrHoistInst().

isNotUsedOrFoldableInLoop()

static bool isNotUsedOrFoldableInLoop ( const Instruction &  I, const Loop *  CurLoop, const LoopSafetyInfo *  SafetyInfo, TargetTransformInfo *  TTI, bool &  FoldableInLoop, bool  LoopNestMode  )

static

Return true if the only users of this instruction are outside of the loop.

If this is true, we can sink the instruction to the exit blocks of the loop.

We also return true if the instruction could be folded away in lowering. (e.g., a GEP can be folded into a load as an addressing mode in the loop).

Definition at line 1385 of file LICM.cpp.

References llvm::LoopBase< BlockT, LoopT >::contains(), llvm::LoopSafetyInfo::getBlockColors(), llvm::User::getNumOperands(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::BasicBlock::getTerminator(), llvm::Value::hasOneUser(), I, isFoldableInLoop(), and llvm::Instruction::user_back().

Referenced by llvm::sinkRegion().

isReassociableOp()

static bool isReassociableOp ( Instruction *  I, unsigned  IntOpcode, unsigned  FPOpcode  )

static

Definition at line 2710 of file LICM.cpp.

References I.

Referenced by FindSingleUseMultiplyFactors(), hoistMulAddAssociation(), LinearizeExprTree(), NegateValue(), ShouldBreakUpSubtract(), and shouldConvertOrWithNoCommonBitsToAdd().

isSafeToExecuteUnconditionally()

static bool isSafeToExecuteUnconditionally ( Instruction &  Inst, const DominatorTree *  DT, const TargetLibraryInfo *  TLI, const Loop *  CurLoop, const LoopSafetyInfo *  SafetyInfo, OptimizationRemarkEmitter *  ORE, const Instruction *  CtxI, AssumptionCache *  AC, bool  AllowSpeculation  )

static

Only sink or hoist an instruction if it is not a trapping instruction, or if the instruction is known not to trap when moved to the preheader.

or if it is a trapping instruction and is guaranteed to execute.

Definition at line 1787 of file LICM.cpp.

References DEBUG_TYPE, llvm::OptimizationRemarkEmitter::emit(), llvm::LoopSafetyInfo::isGuaranteedToExecute(), llvm::Loop::isLoopInvariant(), and llvm::isSafeToSpeculativelyExecute().

Referenced by llvm::hoistRegion(), and llvm::promoteLoopAccessesToScalars().

isTriviallyReplaceablePHI()

static bool isTriviallyReplaceablePHI ( const PHINode &  PN, const Instruction &  I  )

static

Returns true if a PHINode is a trivially replaceable with an Instruction.

This is true when all incoming values are that instruction. This pattern occurs most often with LCSSA PHI nodes.

Definition at line 1346 of file LICM.cpp.

References I, and llvm::PHINode::incoming_values().

Referenced by sink(), and sinkThroughTriviallyReplaceablePHI().

moveInstructionBefore()

static void moveInstructionBefore ( Instruction &  I, BasicBlock::iterator  Dest, ICFLoopSafetyInfo &  SafetyInfo, MemorySSAUpdater &  MSSAU, ScalarEvolution *  SE  )

static

Definition at line 1511 of file LICM.cpp.

References llvm::MemorySSA::BeforeTerminator, llvm::ScalarEvolution::forgetBlockAndLoopDispositions(), llvm::MemorySSA::getMemoryAccess(), llvm::MemorySSAUpdater::getMemorySSA(), I, llvm::ICFLoopSafetyInfo::insertInstructionTo(), llvm::MemorySSAUpdater::moveToPlace(), and llvm::ICFLoopSafetyInfo::removeInstruction().

Referenced by hoist(), and llvm::hoistRegion().

pointerInvalidatedByBlock()

bool pointerInvalidatedByBlock ( BasicBlock &  BB, MemorySSA &  MSSA, MemoryUse &  MU  )

static

Definition at line 2409 of file LICM.cpp.

References llvm::MemoryAccess::getBlock(), llvm::MemorySSA::getBlockDefs(), and llvm::MemorySSA::locallyDominates().

Referenced by pointerInvalidatedByLoop().

pointerInvalidatedByLoop()

static bool pointerInvalidatedByLoop ( MemorySSA *  MSSA, MemoryUse *  MU, Loop *  CurLoop, Instruction &  I, SinkAndHoistLICMFlags &  Flags, bool  InvariantGroup  )

static

Definition at line 2358 of file LICM.cpp.

References llvm::LoopBase< BlockT, LoopT >::contains(), llvm::MemorySSA::getAA(), llvm::LoopBase< BlockT, LoopT >::getBlocks(), getClobberingMemoryAccess(), llvm::LoopBase< BlockT, LoopT >::getHeader(), I, llvm::MemorySSA::isLiveOnEntryDef(), and pointerInvalidatedByBlock().

Referenced by llvm::canSinkOrHoistInst().

sink()

static bool sink ( Instruction &  I, LoopInfo *  LI, DominatorTree *  DT, const Loop *  CurLoop, ICFLoopSafetyInfo *  SafetyInfo, MemorySSAUpdater &  MSSAU, OptimizationRemarkEmitter *  ORE  )

static

When an instruction is found to only be used outside of the loop, this function moves it to the exit blocks and patches up SSA form as needed.

This method is guaranteed to remove the original instruction from its position, and may either delete it or move it to outside of the loop.

Definition at line 1634 of file LICM.cpp.

References assert(), llvm::SmallVectorTemplateCommon< T, typename >::begin(), canSplitPredecessors(), llvm::LoopBase< BlockT, LoopT >::contains(), llvm::SmallPtrSetImpl< PtrType >::count(), llvm::dbgs(), DEBUG_TYPE, llvm::OptimizationRemarkEmitter::emit(), llvm::SmallPtrSetImplBase::empty(), llvm::SmallVectorTemplateCommon< T, typename >::end(), eraseInstruction(), llvm::PoisonValue::get(), llvm::PHINode::getIncomingBlock(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::LoopBase< BlockT, LoopT >::getUniqueExitBlocks(), I, llvm::SmallPtrSetImpl< PtrType >::insert(), llvm::DominatorTree::isReachableFromEntry(), isTriviallyReplaceablePHI(), LLVM_DEBUG, llvm::Value::replaceAllUsesWith(), sinkThroughTriviallyReplaceablePHI(), splitPredecessorsOfLoopExit(), and Users.

Referenced by llvm::GCOVFile::readGCDA(), and llvm::sinkRegion().

sinkThroughTriviallyReplaceablePHI()

static Instruction * sinkThroughTriviallyReplaceablePHI ( PHINode *  TPN, Instruction *  I, LoopInfo *  LI, SmallDenseMap< BasicBlock *, Instruction *, 32 > &  SunkCopies, const LoopSafetyInfo *  SafetyInfo, const Loop *  CurLoop, MemorySSAUpdater &  MSSAU  )

static

Definition at line 1526 of file LICM.cpp.

References assert(), cloneInstructionInExitBlock(), llvm::DenseMapBase< DerivedT, KeyT, ValueT, KeyInfoT, BucketT >::end(), llvm::DenseMapBase< DerivedT, KeyT, ValueT, KeyInfoT, BucketT >::find(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), I, and isTriviallyReplaceablePHI().

Referenced by sink().

splitPredecessorsOfLoopExit()

static void splitPredecessorsOfLoopExit ( PHINode *  PN, DominatorTree *  DT, LoopInfo *  LI, const Loop *  CurLoop, LoopSafetyInfo *  SafetyInfo, MemorySSAUpdater *  MSSAU  )

static

Definition at line 1561 of file LICM.cpp.

References assert(), llvm::SetVector< T, Vector, Set, N >::begin(), llvm::SmallVectorTemplateCommon< T, typename >::begin(), llvm::LoopBase< BlockT, LoopT >::contains(), llvm::LoopSafetyInfo::copyColors(), llvm::SmallPtrSetImpl< PtrType >::count(), llvm::SetVector< T, Vector, Set, N >::empty(), llvm::SmallVectorTemplateCommon< T, typename >::end(), llvm::PHINode::getBasicBlockIndex(), llvm::LoopSafetyInfo::getBlockColors(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::LoopBase< BlockT, LoopT >::getUniqueExitBlocks(), llvm::pred_begin(), llvm::pred_end(), llvm::SetVector< T, Vector, Set, N >::remove(), and llvm::SplitBlockPredecessors().

Referenced by sink().

STATISTIC() [1/15]

STATISTIC	(	NumAddSubHoisted	,
		"Number of add/subtract expressions reassociated " "and hoisted out of the loop"
	)

STATISTIC() [2/15]

STATISTIC	(	NumBOAssociationsHoisted	,
		"Number of invariant BinaryOp expressions " "reassociated and hoisted out of the loop"
	)

STATISTIC() [3/15]

STATISTIC	(	NumClonedBranches	,
		"Number of branches cloned"
	)

STATISTIC() [4/15]

STATISTIC	(	NumCreatedBlocks	,
		"Number of blocks created"
	)

STATISTIC() [5/15]

STATISTIC	(	NumFPAssociationsHoisted	,
		"Number of invariant FP expressions " "reassociated and hoisted out of the loop"
	)

STATISTIC() [6/15]

STATISTIC	(	NumGEPsHoisted	,
		"Number of geps reassociated and hoisted out of the loop"
	)

STATISTIC() [7/15]

STATISTIC	(	NumHoisted	,
		"Number of instructions hoisted out of loop"
	)

STATISTIC() [8/15]

STATISTIC	(	NumIntAssociationsHoisted	,
		"Number of invariant int expressions " "reassociated and hoisted out of the loop"
	)

STATISTIC() [9/15]

STATISTIC	(	NumLoadPromoted	,
		"Number of load-only promotions"
	)

STATISTIC() [10/15]

STATISTIC	(	NumLoadStorePromoted	,
		"Number of load and store promotions"
	)

STATISTIC() [11/15]

STATISTIC	(	NumMinMaxHoisted	,
		"Number of min/max expressions hoisted out of the loop"
	)

STATISTIC() [12/15]

STATISTIC	(	NumMovedCalls	,
		"Number of call insts hoisted or sunk"
	)

STATISTIC() [13/15]

STATISTIC	(	NumMovedLoads	,
		"Number of load insts hoisted or sunk"
	)

STATISTIC() [14/15]

STATISTIC	(	NumPromotionCandidates	,
		"Number of promotion candidates"
	)

STATISTIC() [15/15]

STATISTIC	(	NumSunk	,
		"Number of instructions sunk out of loop"
	)

Variable Documentation

ControlFlowHoisting

cl::opt< bool > ControlFlowHoisting("licm-control-flow-hoisting", cl::Hidden, cl::init(false), cl::desc("Enable control flow (and PHI) hoisting in LICM")) ( "licm-control-flow-hoisting"  , cl::Hidden  , cl::init(false)  , cl::desc("Enable control flow (and PHI) hoisting in LICM")    )

static

Referenced by llvm::hoistRegion().

DisablePromotion

cl::opt< bool > DisablePromotion("disable-licm-promotion", cl::Hidden, cl::init(false), cl::desc("Disable memory promotion in LICM pass")) ( "disable-licm-promotion"  , cl::Hidden  , cl::init(false)  , cl::desc("Disable memory promotion in LICM pass")    )

static

Memory promotion is enabled by default.

false

Loop Invariant Code false

Definition at line 378 of file LICM.cpp.

FPAssociationUpperLimit

cl::opt< unsigned > FPAssociationUpperLimit("licm-max-num-fp-reassociations", cl::init(5U), cl::Hidden, cl::desc( "Set upper limit for the number of transformations performed " "during a single round of hoisting the reassociated expressions.")) ( "licm-max-num-fp-reassociations"  , cl::init(5U)  , cl::Hidden  , cl::desc( "Set upper limit for the number of transformations performed " "during a single round of hoisting the reassociated expressions.")    )

static

Referenced by hoistMulAddAssociation().

IntAssociationUpperLimit

cl::opt< unsigned > IntAssociationUpperLimit("licm-max-num-int-reassociations", cl::init(5U), cl::Hidden, cl::desc( "Set upper limit for the number of transformations performed " "during a single round of hoisting the reassociated expressions."))	(	"licm-max-num-int-reassociations"	,
		cl::init(5U)	,
		cl::Hidden	,
		cl::desc( "Set upper limit for the number of transformations performed " "during a single round of hoisting the reassociated expressions.")
	)

Referenced by hoistMulAddAssociation().

licm

licm

Definition at line 378 of file LICM.cpp.

Referenced by llvm::VPlanTransforms::optimize().

MaxNumUsesTraversed

cl::opt< uint32_t > MaxNumUsesTraversed("licm-max-num-uses-traversed", cl::Hidden, cl::init(8), cl::desc("Max num uses visited for identifying load " "invariance in loop using invariant start (default = 8)")) ( "licm-max-num-uses-traversed"  , cl::Hidden  , cl::init(8)  , cl::desc("Max num uses visited for identifying load " "invariance in loop using invariant start (default = 8)")    )

static

Referenced by isLoadInvariantInLoop().

Motion

Loop Invariant Code Motion

Definition at line 378 of file LICM.cpp.

SingleThread

cl::opt< bool > SingleThread("licm-force-thread-model-single", cl::Hidden, cl::init(false), cl::desc("Force thread model single in LICM pass")) ( "licm-force-thread-model-single"  , cl::Hidden  , cl::init(false)  , cl::desc("Force thread model single in LICM pass")    )

static