This class uses information about analyze scalars to rewrite expressions in canonical form. More...

#include "llvm/Transforms/Utils/ScalarEvolutionExpander.h"

Inheritance diagram for llvm::SCEVExpander:

Public Member Functions
	SCEVExpander (ScalarEvolution &se, const DataLayout &DL, const char *name, bool PreserveLCSSA=true)
	Construct a SCEVExpander in "canonical" mode.

	~SCEVExpander ()

void	clear ()
	Erase the contents of the InsertedExpressions map so that users trying to expand the same expression into multiple BasicBlocks or different places within the same BasicBlock can do so.

ScalarEvolution *	getSE ()

const SmallVectorImpl< WeakVH > &	getInsertedIVs () const

SmallVector< Instruction *, 32 >	getAllInsertedInstructions () const
	Return a vector containing all instructions inserted during expansion.

bool	isHighCostExpansion (ArrayRef< const SCEV * > Exprs, Loop L, unsigned Budget, const TargetTransformInfo TTI, const Instruction *At)
	Return true for expressions that can't be evaluated at runtime within given Budget.

Instruction *	getIVIncOperand (Instruction IncV, Instruction InsertPos, bool allowScale)
	Return the induction variable increment's IV operand.

bool	hoistIVInc (Instruction IncV, Instruction InsertPos, bool RecomputePoisonFlags=false)
	Utility for hoisting `IncV` (with all subexpressions requried for its computation) before `InsertPos`.

unsigned	replaceCongruentIVs (Loop L, const DominatorTree DT, SmallVectorImpl< WeakTrackingVH > &DeadInsts, const TargetTransformInfo *TTI=nullptr)
	replace congruent phis with their most canonical representative.

bool	isSafeToExpand (const SCEV *S) const
	Return true if the given expression is safe to expand in the sense that all materialized values are safe to speculate anywhere their operands are defined, and the expander is capable of expanding the expression.

bool	isSafeToExpandAt (const SCEV S, const Instruction InsertionPoint) const
	Return true if the given expression is safe to expand in the sense that all materialized values are defined and safe to speculate at the specified location and their operands are defined at this location.

Value *	expandCodeFor (const SCEV SH, Type Ty, BasicBlock::iterator I)
	Insert code to directly compute the specified SCEV expression into the program.

Value *	expandCodeFor (const SCEV SH, Type Ty, Instruction *I)

Value *	expandCodeFor (const SCEV SH, Type Ty=nullptr)
	Insert code to directly compute the specified SCEV expression into the program.

Value *	expandCodeForPredicate (const SCEVPredicate Pred, Instruction Loc)
	Generates a code sequence that evaluates this predicate.

Value *	expandComparePredicate (const SCEVComparePredicate Pred, Instruction Loc)
	A specialized variant of expandCodeForPredicate, handling the case when we are expanding code for a SCEVComparePredicate.

Value *	generateOverflowCheck (const SCEVAddRecExpr AR, Instruction Loc, bool Signed)
	Generates code that evaluates if the `AR` expression will overflow.

Value *	expandWrapPredicate (const SCEVWrapPredicate P, Instruction Loc)
	A specialized variant of expandCodeForPredicate, handling the case when we are expanding code for a SCEVWrapPredicate.

Value *	expandUnionPredicate (const SCEVUnionPredicate Pred, Instruction Loc)
	A specialized variant of expandCodeForPredicate, handling the case when we are expanding code for a SCEVUnionPredicate.

void	setIVIncInsertPos (const Loop L, Instruction Pos)
	Set the current IV increment loop and position.

void	setPostInc (const PostIncLoopSet &L)
	Enable post-inc expansion for addrecs referring to the given loops.

void	clearPostInc ()
	Disable all post-inc expansion.

void	disableCanonicalMode ()
	Disable the behavior of expanding expressions in canonical form rather than in a more literal form.

void	enableLSRMode ()

void	setInsertPoint (Instruction *IP)
	Set the current insertion point.

void	setInsertPoint (BasicBlock::iterator IP)

void	clearInsertPoint ()
	Clear the current insertion point.

void	SetCurrentDebugLocation (DebugLoc L)
	Set location information used by debugging information.

DebugLoc	getCurrentDebugLocation () const
	Get location information used by debugging information.

bool	isInsertedInstruction (Instruction *I) const
	Return true if the specified instruction was inserted by the code rewriter.

void	setChainedPhi (PHINode *PN)

bool	hasRelatedExistingExpansion (const SCEV S, const Instruction At, Loop *L)
	Determine whether there is an existing expansion of S that can be reused.

BasicBlock::iterator	findInsertPointAfter (Instruction I, Instruction MustDominate) const
	Returns a suitable insert point after `I`, that dominates `MustDominate`.

Public Member Functions inherited from llvm::SCEVVisitor< SCEVExpander, Value * >
Value *	visit (const SCEV *S)

Value *	visitCouldNotCompute (const SCEVCouldNotCompute *S)

Friends
struct	SCEVVisitor< SCEVExpander, Value * >

Detailed Description

This class uses information about analyze scalars to rewrite expressions in canonical form.

Clients should create an instance of this class when rewriting is needed, and destroy it when finished to allow the release of the associated memory.

Definition at line 50 of file ScalarEvolutionExpander.h.

Constructor & Destructor Documentation

◆ SCEVExpander()

llvm::SCEVExpander::SCEVExpander	(	ScalarEvolution &	se,
		const DataLayout &	DL,
		const char *	name,
		bool	PreserveLCSSA = `true`
	)

inlineexplicit

Construct a SCEVExpander in "canonical" mode.

Definition at line 161 of file ScalarEvolutionExpander.h.

References I.

◆ ~SCEVExpander()

llvm::SCEVExpander::~SCEVExpander ( )

inline

Definition at line 174 of file ScalarEvolutionExpander.h.

References assert(), and llvm::SmallVectorBase< Size_T >::empty().

Member Function Documentation

◆ clear()

void llvm::SCEVExpander::clear ( )

inline

Erase the contents of the InsertedExpressions map so that users trying to expand the same expression into multiple BasicBlocks or different places within the same BasicBlock can do so.

Definition at line 186 of file ScalarEvolutionExpander.h.

References llvm::SmallPtrSetImplBase::clear().

Referenced by llvm::SCEVExpanderCleaner::cleanup().

◆ clearInsertPoint()

void llvm::SCEVExpander::clearInsertPoint ( )

inline

Clear the current insertion point.

This is useful if the instruction that had been serving as the insertion point may have been deleted.

Definition at line 359 of file ScalarEvolutionExpander.h.

References llvm::IRBuilderBase::ClearInsertionPoint().

◆ clearPostInc()

void llvm::SCEVExpander::clearPostInc ( )

inline

Disable all post-inc expansion.

Definition at line 329 of file ScalarEvolutionExpander.h.

References llvm::SmallPtrSetImplBase::clear().

◆ disableCanonicalMode()

void llvm::SCEVExpander::disableCanonicalMode ( )

inline

Disable the behavior of expanding expressions in canonical form rather than in a more literal form.

Non-canonical mode is useful for late optimization passes.

Definition at line 340 of file ScalarEvolutionExpander.h.

◆ enableLSRMode()

void llvm::SCEVExpander::enableLSRMode ( )

inline

Definition at line 342 of file ScalarEvolutionExpander.h.

◆ expandCodeFor() [1/3]

Value * SCEVExpander::expandCodeFor	(	const SCEV *	SH,
		Type *	Ty,
		BasicBlock::iterator	I
	)

Insert code to directly compute the specified SCEV expression into the program.

The code is inserted into the specified block.

Definition at line 1354 of file ScalarEvolutionExpander.cpp.

References expandCodeFor(), and setInsertPoint().

Referenced by llvm::addDiffRuntimeChecks(), expandCodeFor(), llvm::LoopStructure::parseLoopStructure(), ReduceLoopStrength(), llvm::LoopConstrainer::run(), llvm::splitLoopBound(), and llvm::UnrollRuntimeLoopRemainder().

◆ expandCodeFor() [2/3]

Value * llvm::SCEVExpander::expandCodeFor	(	const SCEV *	SH,
		Type *	Ty,
		Instruction *	I
	)

inline

Definition at line 280 of file ScalarEvolutionExpander.h.

References expandCodeFor(), and I.

◆ expandCodeFor() [3/3]

Value * SCEVExpander::expandCodeFor	(	const SCEV *	SH,
		Type *	Ty = `nullptr`
	)

Insert code to directly compute the specified SCEV expression into the program.

The code is inserted into the SCEVExpander's current insertion point. If a type is specified, the result will be expanded to have that type, with a cast if necessary.

Definition at line 1361 of file ScalarEvolutionExpander.cpp.

References assert(), llvm::SCEV::getType(), and llvm::ScalarEvolution::getTypeSizeInBits().

◆ expandCodeForPredicate()

Value * SCEVExpander::expandCodeForPredicate	(	const SCEVPredicate *	Pred,
		Instruction *	Loc
	)

Generates a code sequence that evaluates this predicate.

The inserted instructions will be at position Loc. The result will be of type i1 and will have a value of 0 when the predicate is false and 1 otherwise.

Definition at line 2000 of file ScalarEvolutionExpander.cpp.

References assert(), expandComparePredicate(), expandUnionPredicate(), expandWrapPredicate(), llvm::SCEVPredicate::getKind(), llvm_unreachable, llvm::SCEVPredicate::P_Compare, llvm::SCEVPredicate::P_Union, and llvm::SCEVPredicate::P_Wrap.

Referenced by expandUnionPredicate().

◆ expandComparePredicate()

Value * SCEVExpander::expandComparePredicate	(	const SCEVComparePredicate *	Pred,
		Instruction *	Loc
	)

A specialized variant of expandCodeForPredicate, handling the case when we are expanding code for a SCEVComparePredicate.

Definition at line 2016 of file ScalarEvolutionExpander.cpp.

References llvm::IRBuilderBase::CreateICmp(), llvm::CmpInst::getInversePredicate(), llvm::SCEVComparePredicate::getLHS(), llvm::SCEVComparePredicate::getPredicate(), llvm::SCEVComparePredicate::getRHS(), I, and llvm::IRBuilderBase::SetInsertPoint().

Referenced by expandCodeForPredicate().

◆ expandUnionPredicate()

Value * SCEVExpander::expandUnionPredicate	(	const SCEVUnionPredicate *	Pred,
		Instruction *	Loc
	)

A specialized variant of expandCodeForPredicate, handling the case when we are expanding code for a SCEVUnionPredicate.

Definition at line 2177 of file ScalarEvolutionExpander.cpp.

References llvm::IRBuilderBase::CreateOr(), llvm::SmallVectorBase< Size_T >::empty(), expandCodeForPredicate(), llvm::Value::getContext(), llvm::ConstantInt::getFalse(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), and llvm::IRBuilderBase::SetInsertPoint().

Referenced by expandCodeForPredicate().

◆ expandWrapPredicate()

Value * SCEVExpander::expandWrapPredicate	(	const SCEVWrapPredicate *	P,
		Instruction *	Loc
	)

A specialized variant of expandCodeForPredicate, handling the case when we are expanding code for a SCEVWrapPredicate.

Definition at line 2152 of file ScalarEvolutionExpander.cpp.

References A, llvm::IRBuilderBase::CreateOr(), generateOverflowCheck(), llvm::Value::getContext(), llvm::SCEVWrapPredicate::getExpr(), llvm::ConstantInt::getFalse(), llvm::SCEVWrapPredicate::getFlags(), llvm::SCEVWrapPredicate::IncrementNSSW, and llvm::SCEVWrapPredicate::IncrementNUSW.

Referenced by expandCodeForPredicate().

◆ findInsertPointAfter()

BasicBlock::iterator SCEVExpander::findInsertPointAfter	(	Instruction *	I,
		Instruction *	MustDominate
	)		const

Returns a suitable insert point after I, that dominates MustDominate.

Skips instructions inserted by the expander.

Definition at line 99 of file ScalarEvolutionExpander.cpp.

References assert(), llvm::BasicBlock::getFirstInsertionPt(), llvm::Instruction::getParent(), I, and isInsertedInstruction().

◆ generateOverflowCheck()

Value * SCEVExpander::generateOverflowCheck	(	const SCEVAddRecExpr *	AR,
		Instruction *	Loc,
		bool	Signed
	)

Generates code that evaluates if the AR expression will overflow.

Definition at line 2027 of file ScalarEvolutionExpander.cpp.

Referenced by expandWrapPredicate().

◆ getAllInsertedInstructions()

SmallVector< Instruction *, 32 > llvm::SCEVExpander::getAllInsertedInstructions ( ) const

inline

Return a vector containing all instructions inserted during expansion.

Definition at line 199 of file ScalarEvolutionExpander.h.

References llvm::SmallPtrSetImpl< PtrType >::contains().

Referenced by llvm::SCEVExpanderCleaner::cleanup().

◆ getCurrentDebugLocation()

DebugLoc llvm::SCEVExpander::getCurrentDebugLocation ( ) const

inline

Get location information used by debugging information.

Definition at line 367 of file ScalarEvolutionExpander.h.

References llvm::IRBuilderBase::getCurrentDebugLocation().

◆ getInsertedIVs()

const SmallVectorImpl< WeakVH > & llvm::SCEVExpander::getInsertedIVs ( ) const

inline

Definition at line 196 of file ScalarEvolutionExpander.h.

◆ getIVIncOperand()

Instruction * SCEVExpander::getIVIncOperand	(	Instruction *	IncV,
		Instruction *	InsertPos,
		bool	allowScale
	)

Return the induction variable increment's IV operand.

getIVIncOperand returns an induction variable increment's induction variable operand.

If allowScale is set, any type of GEP is allowed as long as the nonIV operands dominate InsertPos.

If allowScale is not set, ensure that a GEP increment conforms to one of the simple patterns generated by getAddRecExprPHILiterally and expandAddtoGEP. If the pattern isn't recognized, return NULL.

Definition at line 666 of file ScalarEvolutionExpander.cpp.

References llvm::DominatorTree::dominates(), llvm::drop_begin(), llvm::Instruction::getOpcode(), llvm::User::getOperand(), and llvm::User::operands().

Referenced by hoistIVInc().

◆ getSE()

ScalarEvolution * llvm::SCEVExpander::getSE ( )

inline

Definition at line 195 of file ScalarEvolutionExpander.h.

Referenced by llvm::addDiffRuntimeChecks().

◆ hasRelatedExistingExpansion()

bool SCEVExpander::hasRelatedExistingExpansion	(	const SCEV *	S,
		const Instruction *	At,
		Loop *	L
	)

Determine whether there is an existing expansion of S that can be reused.

This is used to check whether S can be expanded cheaply.

L is a hint which tells in which loop to look for the suitable value.

Note that this function does not perform an exhaustive search. I.e if it didn't find any value it does not mean that there is no such value.

Definition at line 1716 of file ScalarEvolutionExpander.cpp.

References llvm::DominatorTree::dominates(), llvm::ScalarEvolution::getSCEV(), LHS, llvm::PatternMatch::m_BasicBlock(), llvm::PatternMatch::m_Br(), llvm::PatternMatch::m_ICmp(), llvm::PatternMatch::m_Instruction(), llvm::PatternMatch::match(), and RHS.

◆ hoistIVInc()

bool SCEVExpander::hoistIVInc	(	Instruction *	IncV,
		Instruction *	InsertPos,
		bool	RecomputePoisonFlags = `false`
	)

Utility for hoisting IncV (with all subexpressions requried for its computation) before InsertPos.

hoistStep - Attempt to hoist a simple IV increment above InsertPos to make it available to other uses in this loop.

If RecomputePoisonFlags is set, drops all poison-generating flags from instructions being hoisted and tries to re-infer them in the new location. It should be used when we are going to introduce a new use in the new position that didn't exist before, and may trigger new UB in case of poison.

Recursively hoist any operands, until we reach a value that dominates InsertPos.

Definition at line 726 of file ScalarEvolutionExpander.cpp.

References llvm::DominatorTree::dominates(), llvm::SCEV::FlagNSW, llvm::SCEV::FlagNUW, getIVIncOperand(), llvm::Instruction::getParent(), llvm::ScalarEvolution::getStrengthenedNoWrapFlagsFromBinOp(), I, llvm::ScalarEvolution::maskFlags(), llvm::LoopInfo::movementPreservesLCSSAForm(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::reverse(), llvm::Instruction::setHasNoSignedWrap(), and llvm::Instruction::setHasNoUnsignedWrap().

Referenced by replaceCongruentIVs().

◆ isHighCostExpansion()

bool llvm::SCEVExpander::isHighCostExpansion	(	ArrayRef< const SCEV * >	Exprs,
		Loop *	L,
		unsigned	Budget,
		const TargetTransformInfo *	TTI,
		const Instruction *	At
	)

inline

Return true for expressions that can't be evaluated at runtime within given Budget.

At is a parameter which specifies point in code where user is going to expand these expressions. Sometimes this knowledge can lead to a less pessimistic cost estimation.

Definition at line 225 of file ScalarEvolutionExpander.h.

References assert(), llvm::SmallVectorImpl< T >::emplace_back(), llvm::SmallVectorBase< Size_T >::empty(), llvm::SmallVectorImpl< T >::pop_back_val(), and llvm::TargetTransformInfo::TCC_Basic.

Referenced by llvm::UnrollRuntimeLoopRemainder().

◆ isInsertedInstruction()

bool llvm::SCEVExpander::isInsertedInstruction ( Instruction * I ) const

inline

Return true if the specified instruction was inserted by the code rewriter.

If so, the client should not modify the instruction. Note that this also includes instructions re-used during expansion.

Definition at line 374 of file ScalarEvolutionExpander.h.

References I.

Referenced by findInsertPointAfter().

◆ isSafeToExpand()

bool SCEVExpander::isSafeToExpand ( const SCEV * S ) const

Return true if the given expression is safe to expand in the sense that all materialized values are safe to speculate anywhere their operands are defined, and the expander is capable of expanding the expression.

Definition at line 2287 of file ScalarEvolutionExpander.cpp.

References llvm::visitAll().

Referenced by canFoldTermCondOfLoop(), isSafeToExpandAt(), and ReduceLoopStrength().

◆ isSafeToExpandAt()

bool SCEVExpander::isSafeToExpandAt	(	const SCEV *	S,
		const Instruction *	InsertionPoint
	)		const

Return true if the given expression is safe to expand in the sense that all materialized values are defined and safe to speculate at the specified location and their operands are defined at this location.

Definition at line 2293 of file ScalarEvolutionExpander.cpp.

References llvm::ScalarEvolution::dominates(), llvm::Instruction::getParent(), llvm::BasicBlock::getTerminator(), llvm::is_contained(), isSafeToExpand(), llvm::User::operand_values(), and llvm::ScalarEvolution::properlyDominates().

Referenced by llvm::LoopConstrainer::run().

◆ replaceCongruentIVs()

unsigned SCEVExpander::replaceCongruentIVs	(	Loop *	L,
		const DominatorTree *	DT,
		SmallVectorImpl< WeakTrackingVH > &	DeadInsts,
		const TargetTransformInfo *	TTI = `nullptr`
	)

replace congruent phis with their most canonical representative.

replaceCongruentIVs - Check for congruent phis in this loop header and replace them with their most canonical representative.

Return the number of phis eliminated.

This does not depend on any SCEVExpander state but should be used in the same context that SCEVExpander is used.

Definition at line 1565 of file ScalarEvolutionExpander.cpp.

References llvm::SmallVectorTemplateCommon< T, typename >::back(), llvm::IRBuilderBase::CreateTruncOrBitCast(), llvm::dbgs(), llvm::SmallVectorImpl< T >::emplace_back(), llvm::ScalarEvolution::forgetValue(), llvm::Instruction::getDebugLoc(), llvm::BasicBlock::getFirstInsertionPt(), llvm::details::FixedOrScalableQuantity< LeafTy, ValueTy >::getFixedValue(), llvm::PHINode::getIncomingValueForBlock(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::Instruction::getNextNonDebugInstruction(), llvm::Instruction::getParent(), llvm::Type::getPrimitiveSizeInBits(), llvm::ScalarEvolution::getSCEV(), llvm::ScalarEvolution::getTruncateExpr(), llvm::ScalarEvolution::getTruncateOrNoop(), llvm::Value::getType(), hoistIVInc(), llvm::Type::isIntegerTy(), llvm::Type::isPointerTy(), llvm::ScalarEvolution::isSCEVable(), llvm::TargetTransformInfo::isTruncateFree(), LHS, llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::Value::replaceAllUsesWith(), llvm::LoopInfo::replacementPreservesLCSSAForm(), RHS, SCEV_DEBUG_WITH_TYPE, llvm::IRBuilderBase::SetCurrentDebugLocation(), llvm::simplifyInstruction(), llvm::stable_sort(), and std::swap().

◆ setChainedPhi()

void llvm::SCEVExpander::setChainedPhi ( PHINode * PN )

inline

Definition at line 378 of file ScalarEvolutionExpander.h.

◆ SetCurrentDebugLocation()

void llvm::SCEVExpander::SetCurrentDebugLocation ( DebugLoc L )

inline

Set location information used by debugging information.

Definition at line 362 of file ScalarEvolutionExpander.h.

References llvm::IRBuilderBase::SetCurrentDebugLocation().

◆ setInsertPoint() [1/2]

void llvm::SCEVExpander::setInsertPoint ( BasicBlock::iterator IP )

inline

Definition at line 353 of file ScalarEvolutionExpander.h.

References llvm::IRBuilderBase::SetInsertPoint().

◆ setInsertPoint() [2/2]

void llvm::SCEVExpander::setInsertPoint ( Instruction * IP )

inline

Set the current insertion point.

This is useful if multiple calls to expandCodeFor() are going to be made with the same insert point and the insert point may be moved during one of the expansions (e.g. if the insert point is not a block terminator).

Definition at line 348 of file ScalarEvolutionExpander.h.

References assert(), and llvm::IRBuilderBase::SetInsertPoint().

Referenced by expandCodeFor().

◆ setIVIncInsertPos()

void llvm::SCEVExpander::setIVIncInsertPos	(	const Loop *	L,
		Instruction *	Pos
	)

inline

Set the current IV increment loop and position.

Definition at line 313 of file ScalarEvolutionExpander.h.

References assert().

◆ setPostInc()

void llvm::SCEVExpander::setPostInc ( const PostIncLoopSet & L )

inline

Enable post-inc expansion for addrecs referring to the given loops.

Post-inc expansion is only supported in non-canonical mode.

Definition at line 322 of file ScalarEvolutionExpander.h.

References assert().

Friends And Related Function Documentation

◆ SCEVVisitor< SCEVExpander, Value * >

friend struct SCEVVisitor< SCEVExpander, Value * >

friend

Definition at line 151 of file ScalarEvolutionExpander.h.

The documentation for this class was generated from the following files:

include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
lib/Transforms/Utils/ScalarEvolutionExpander.cpp

Public Member Functions

Friends

Detailed Description

Constructor & Destructor Documentation

◆ SCEVExpander()

◆ ~SCEVExpander()

Member Function Documentation

◆ clear()

◆ clearInsertPoint()

◆ clearPostInc()

◆ disableCanonicalMode()

◆ enableLSRMode()

◆ expandCodeFor() [1/3]

◆ expandCodeFor() [2/3]

◆ expandCodeFor() [3/3]

◆ expandCodeForPredicate()

◆ expandComparePredicate()

◆ expandUnionPredicate()

◆ expandWrapPredicate()

◆ findInsertPointAfter()

◆ generateOverflowCheck()

◆ getAllInsertedInstructions()

◆ getCurrentDebugLocation()

◆ getInsertedIVs()

◆ getIVIncOperand()

◆ getSE()

◆ hasRelatedExistingExpansion()

◆ hoistIVInc()

◆ isHighCostExpansion()

◆ isInsertedInstruction()

◆ isSafeToExpand()

◆ isSafeToExpandAt()

◆ replaceCongruentIVs()

◆ setChainedPhi()

◆ SetCurrentDebugLocation()

◆ setInsertPoint() [1/2]

◆ setInsertPoint() [2/2]

◆ setIVIncInsertPos()

◆ setPostInc()

Friends And Related Function Documentation

◆ SCEVVisitor< SCEVExpander, Value * >