llvm::SCEV Class Reference

This class represents an analyzed expression in the program. More...

#include "llvm/Analysis/ScalarEvolution.h"

Inheritance diagram for llvm::SCEV:

Public Types
enum	NoWrapFlags {   FlagAnyWrap = 0 , FlagNW = (1 << 0) , FlagNUW = (1 << 1) , FlagNSW = (1 << 2) ,   NoWrapMask = (1 << 3) - 1 }
	NoWrapFlags are bitfield indices into SubclassData. More...

Public Member Functions
	SCEV (const FoldingSetNodeIDRef ID, SCEVTypes SCEVTy, unsigned short ExpressionSize)
	SCEV (const SCEV &)=delete
SCEV &	operator= (const SCEV &)=delete
SCEVTypes	getSCEVType () const
Type *	getType () const
	Return the LLVM type of this SCEV expression.
ArrayRef< const SCEV * >	operands () const
	Return operands of this SCEV expression.
bool	isZero () const
	Return true if the expression is a constant zero.
bool	isOne () const
	Return true if the expression is a constant one.
bool	isAllOnesValue () const
	Return true if the expression is a constant all-ones value.
bool	isNonConstantNegative () const
	Return true if the specified scev is negated, but not a constant.
unsigned short	getExpressionSize () const
void	print (raw_ostream &OS) const
	Print out the internal representation of this scalar to the specified stream.
void	dump () const
	This method is used for debugging.
Public Member Functions inherited from llvm::FoldingSetBase::Node
	Node ()=default
void *	getNextInBucket () const
void	SetNextInBucket (void *N)

Protected Attributes
const unsigned short	ExpressionSize
unsigned short	SubclassData = 0
	This field is initialized to zero and may be used in subclasses to store miscellaneous information.

Friends
struct	FoldingSetTrait< SCEV >

Detailed Description

This class represents an analyzed expression in the program.

These are opaque objects that the client is not allowed to do much with directly.

Definition at line 71 of file ScalarEvolution.h.

Member Enumeration Documentation

NoWrapFlags

enum llvm::SCEV::NoWrapFlags

NoWrapFlags are bitfield indices into SubclassData.

Add and Mul expressions may have no-unsigned-wrap <NUW> or no-signed-wrap <NSW> properties, which are derived from the IR operator. NSW is a misnomer that we use to mean no signed overflow or underflow.

AddRec expressions may have a no-self-wraparound <NW> property if, in the integer domain, abs(step) * max-iteration(loop) <= unsigned-max(bitwidth). This means that the recurrence will never reach its start value if the step is non-zero. Computing the same value on each iteration is not considered wrapping, and recurrences with step = 0 are trivially <NW>. <NW> is independent of the sign of step and the value the add recurrence starts with.

Note that NUW and NSW are also valid properties of a recurrence, and either implies NW. For convenience, NW will be set for a recurrence whenever either NUW or NSW are set.

We require that the flag on a SCEV apply to the entire scope in which that SCEV is defined. A SCEV's scope is set of locations dominated by a defining location, which is in turn described by the following rules:

• A SCEVUnknown is at the point of definition of the Value.
• A SCEVConstant is defined at all points.
• A SCEVAddRec is defined starting with the header of the associated loop.
• All other SCEVs are defined at the earlest point all operands are defined.

The above rules describe a maximally hoisted form (without regards to potential control dependence). A SCEV is defined anywhere a corresponding instruction could be defined in said maximally hoisted form. Note that SCEVUDivExpr (currently the only expression type which can trap) can be defined per these rules in regions where it would trap at runtime. A SCEV being defined does not require the existence of any instruction within the defined scope.

Enumerator
FlagAnyWrap
FlagNW
FlagNUW
FlagNSW
NoWrapMask

Definition at line 126 of file ScalarEvolution.h.

Constructor & Destructor Documentation

SCEV() [1/2]

llvm::SCEV::SCEV ( const FoldingSetNodeIDRef  ID, SCEVTypes  SCEVTy, unsigned short  ExpressionSize  )

inlineexplicit

Definition at line 134 of file ScalarEvolution.h.

SCEV() [2/2]

llvm::SCEV::SCEV ( const SCEV &  )

delete

Member Function Documentation

dump()

LLVM_DUMP_METHOD void SCEV::dump

(

)

const

This method is used for debugging.

Definition at line 267 of file ScalarEvolution.cpp.

References llvm::dbgs(), and print().

getExpressionSize()

unsigned short llvm::SCEV::getExpressionSize ( ) const

inline

Definition at line 169 of file ScalarEvolution.h.

References ExpressionSize.

Referenced by hasHugeExpression().

getSCEVType()

SCEVTypes llvm::SCEV::getSCEVType ( ) const

inline

Definition at line 140 of file ScalarEvolution.h.

Referenced by llvm::SCEVCouldNotCompute::classof(), llvm::SCEVConstant::classof(), llvm::SCEVVScale::classof(), llvm::SCEVCastExpr::classof(), llvm::SCEVPtrToIntExpr::classof(), llvm::SCEVIntegralCastExpr::classof(), llvm::SCEVTruncateExpr::classof(), llvm::SCEVZeroExtendExpr::classof(), llvm::SCEVSignExtendExpr::classof(), llvm::SCEVNAryExpr::classof(), llvm::SCEVCommutativeExpr::classof(), llvm::SCEVAddExpr::classof(), llvm::SCEVMulExpr::classof(), llvm::SCEVUDivExpr::classof(), llvm::SCEVAddRecExpr::classof(), llvm::SCEVMinMaxExpr::classof(), llvm::SCEVSMaxExpr::classof(), llvm::SCEVUMaxExpr::classof(), llvm::SCEVSMinExpr::classof(), llvm::SCEVUMinExpr::classof(), llvm::SCEVSequentialMinMaxExpr::classof(), llvm::SCEVSequentialUMinExpr::classof(), llvm::SCEVUnknown::classof(), llvm::SCEVSequentialMinMaxExpr::getEquivalentNonSequentialSCEVType(), getExprBase(), getType(), GroupByComplexity(), isHighCostExpansion(), operands(), print(), SCEVMinMaxExprContains(), llvm::SCEVVisitor< SC, RetVal >::visit(), and llvm::SCEVTraversal< SV >::visitAll().

getType()

Type * SCEV::getType

(

)

const

Return the LLVM type of this SCEV expression.

Definition at line 386 of file ScalarEvolution.cpp.

References getSCEVType(), llvm_unreachable, llvm::scAddExpr, llvm::scAddRecExpr, llvm::scConstant, llvm::scCouldNotCompute, llvm::scMulExpr, llvm::scPtrToInt, llvm::scSequentialUMinExpr, llvm::scSignExtend, llvm::scSMaxExpr, llvm::scSMinExpr, llvm::scTruncate, llvm::scUDivExpr, llvm::scUMaxExpr, llvm::scUMinExpr, llvm::scUnknown, llvm::scVScale, and llvm::scZeroExtend.

Referenced by llvm::SCEVAAResult::alias(), BinomialCoefficient(), calculateRtStride(), llvm::cannotBeMaxInLoop(), llvm::cannotBeMinInLoop(), llvm::ScalarEvolution::computeConstantDifference(), llvm::LoopVectorizationCostModel::computeMaxVF(), llvm::IndexedReference::computeRefCost(), computeTripCount(), countToEliminateCompares(), llvm::VPlan::createInitialVPlan(), createNodeForSelectViaUMinSeq(), createReplacement(), DoInitialMatch(), llvm::VPExpandSCEVRecipe::execute(), llvm::ScalarEvolution::ExitLimit::ExitLimit(), expandBounds(), llvm::SCEVExpander::expandCodeFor(), findForkedSCEVs(), FindLoopCounter(), llvm::SCEVExpander::generateOverflowCheck(), genLoopLimit(), llvm::ScalarEvolution::getAnyExtendExpr(), llvm::ScalarEvolution::getGEPExpr(), llvm::ScalarEvolution::getLoopInvariantExitCondDuringFirstIterationsImpl(), llvm::ScalarEvolution::getLosslessPtrToIntExpr(), llvm::ScalarEvolution::getMinTrailingZeros(), getNewAlignment(), getSignedOverflowLimitForStep(), llvm::ScalarEvolution::getSignExtendExprImpl(), getStartAndEndForAccess(), llvm::ScalarEvolution::getTripCountFromExitCount(), llvm::SCEVMulExpr::getType(), llvm::SCEVUDivExpr::getType(), llvm::SCEVAddRecExpr::getType(), llvm::SCEVMinMaxExpr::getType(), llvm::SCEVSequentialMinMaxExpr::getType(), llvm::ScalarEvolution::getUMinFromMismatchedTypes(), getUnsignedOverflowLimitForStep(), llvm::ScalarEvolution::getZeroExtendExprImpl(), llvm::hasIterationCountInvariantInParent(), llvm::SCEVWrapPredicate::implies(), llvm::ARMTTIImpl::isHardwareLoopProfitable(), llvm::isKnownNegativeInLoop(), llvm::isKnownNonNegativeInLoop(), llvm::isKnownNonPositiveInLoop(), llvm::isKnownPositiveInLoop(), llvm::ScalarEvolution::isLoopBackedgeGuardedByCond(), isSafeDecreasingBound(), isSafeDependenceDistance(), isSafeIncreasingBound(), IsSimplerBaseSCEVForTarget(), llvm::SCEVPatternMatch::cst_pred_ty< Predicate >::match(), llvm::VPlanTransforms::optimizeForVFAndUF(), optimizeLoopExitWithUnknownExitCount(), llvm::LoopStructure::parseLoopStructure(), PrintSCEVWithTypeHint(), llvm::replaceSymbolicStrideSCEV(), llvm::splitLoopBound(), llvm::UnrollRuntimeLoopRemainder(), verifyTripCount(), llvm::SCEVDivision::visitAddExpr(), llvm::SCEVDivision::visitAddRecExpr(), and llvm::SCEVDivision::visitMulExpr().

isAllOnesValue()

bool SCEV::isAllOnesValue

(

)

const

Return true if the expression is a constant all-ones value.

Definition at line 452 of file ScalarEvolution.cpp.

References llvm::SCEVPatternMatch::m_scev_AllOnes(), and llvm::PatternMatch::match().

Referenced by MatchNotExpr().

isNonConstantNegative()

bool SCEV::isNonConstantNegative

(

)

const

Return true if the specified scev is negated, but not a constant.

Definition at line 454 of file ScalarEvolution.cpp.

References llvm::Mul.

Referenced by calculateRtStride().

isOne()

bool SCEV::isOne

(

)

const

Return true if the expression is a constant one.

Definition at line 450 of file ScalarEvolution.cpp.

References llvm::SCEVPatternMatch::m_scev_One(), and llvm::PatternMatch::match().

Referenced by llvm::SCEVDivision::divide(), llvm::SCEVExpander::generateOverflowCheck(), genLoopLimit(), llvm::LoopVectorizationCostModel::getInstructionCost(), getStartForNegStride(), and isLoopCounter().

isZero()

bool SCEV::isZero

(

)

const

Return true if the expression is a constant zero.

Definition at line 448 of file ScalarEvolution.cpp.

References llvm::SCEVPatternMatch::m_scev_Zero(), and llvm::PatternMatch::match().

Referenced by breakBackedgeIfNotTaken(), calculateRtStride(), CollectSubexprs(), llvm::LoopVectorizationCostModel::computeMaxVF(), llvm::SCEVDivision::divide(), llvm::ScalarEvolution::ExitLimit::ExitLimit(), llvm::findArrayDimensions(), FindLoopCounter(), isAlwaysFoldable(), llvm::VPlanTransforms::optimizeForVFAndUF(), SolveQuadraticAddRecRange(), llvm::ScalarEvolution::verify(), and llvm::SCEVDivision::visitMulExpr().

operands()

ArrayRef< const SCEV * > SCEV::operands

(

)

const

Return operands of this SCEV expression.

Definition at line 420 of file ScalarEvolution.cpp.

References getSCEVType(), llvm_unreachable, llvm::scAddExpr, llvm::scAddRecExpr, llvm::scConstant, llvm::scCouldNotCompute, llvm::scMulExpr, llvm::scPtrToInt, llvm::scSequentialUMinExpr, llvm::scSignExtend, llvm::scSMaxExpr, llvm::scSMinExpr, llvm::scTruncate, llvm::scUDivExpr, llvm::scUMaxExpr, llvm::scUMinExpr, llvm::scUnknown, llvm::scVScale, and llvm::scZeroExtend.

Referenced by llvm::ScalarEvolution::computeConstantDifference(), llvm::ScalarEvolution::getMulExpr(), llvm::ScalarEvolution::getNotSCEV(), getSetupCost(), llvm::ScalarEvolution::verify(), and llvm::SCEVTraversal< SV >::visitAll().

operator=()

SCEV & llvm::SCEV::operator= ( const SCEV &  )

delete

print()

void SCEV::print

(

raw_ostream &

OS

)

const

Print out the internal representation of this scalar to the specified stream.

This should really only be used for debugging purposes.

Definition at line 273 of file ScalarEvolution.cpp.

References FlagNSW, FlagNUW, llvm::LoopBase< BlockT, LoopT >::getHeader(), llvm::SCEVUDivExpr::getLHS(), llvm::SCEVAddRecExpr::getLoop(), llvm::SCEVNAryExpr::getNoWrapFlags(), llvm::SCEVNAryExpr::getNumOperands(), llvm::SCEVCastExpr::getOperand(), llvm::SCEVNAryExpr::getOperand(), llvm::SCEVUDivExpr::getRHS(), getSCEVType(), llvm::SCEVCastExpr::getType(), llvm::SCEVNAryExpr::hasNoSelfWrap(), llvm::SCEVNAryExpr::hasNoSignedWrap(), llvm::SCEVNAryExpr::hasNoUnsignedWrap(), llvm_unreachable, llvm::SCEVNAryExpr::operands(), OS, llvm::Value::printAsOperand(), llvm::scAddExpr, llvm::scAddRecExpr, llvm::scConstant, llvm::scCouldNotCompute, llvm::scMulExpr, llvm::scPtrToInt, llvm::scSequentialUMinExpr, llvm::scSignExtend, llvm::scSMaxExpr, llvm::scSMinExpr, llvm::scTruncate, llvm::scUDivExpr, llvm::scUMaxExpr, llvm::scUMinExpr, llvm::scUnknown, llvm::scVScale, and llvm::scZeroExtend.

Referenced by dump(), llvm::operator<<(), and llvm::ScalarEvolution::print().

Friends And Related Function Documentation

FoldingSetTrait< SCEV >

friend struct FoldingSetTrait< SCEV >

friend

Definition at line 412 of file ScalarEvolution.h.

Member Data Documentation

ExpressionSize

const unsigned short llvm::SCEV::ExpressionSize

protected

Definition at line 83 of file ScalarEvolution.h.

Referenced by getExpressionSize().

SubclassData

unsigned short llvm::SCEV::SubclassData = 0

protected

This field is initialized to zero and may be used in subclasses to store miscellaneous information.

Definition at line 87 of file ScalarEvolution.h.

Referenced by llvm::SCEVNAryExpr::getNoWrapFlags(), llvm::SCEVCommutativeExpr::setNoWrapFlags(), and llvm::SCEVAddRecExpr::setNoWrapFlags().

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

• include/llvm/Analysis/ScalarEvolution.h
• lib/Analysis/ScalarEvolution.cpp