This node represents a polynomial recurrence on the trip count of the specified loop. More...

#include "llvm/Analysis/ScalarEvolutionExpressions.h"

Inheritance diagram for llvm::SCEVAddRecExpr:

Public Member Functions
Type *	getType () const
const SCEV *	getStart () const
const Loop *	getLoop () const
const SCEV *	getStepRecurrence (ScalarEvolution &SE) const
	Constructs and returns the recurrence indicating how much this expression steps by.
bool	isAffine () const
	Return true if this represents an expression A + B*x where A and B are loop invariant values.
bool	isQuadratic () const
	Return true if this represents an expression A + Bx + Cx^2 where A, B and C are loop invariant values.
void	setNoWrapFlags (NoWrapFlags Flags)
	Set flags for a recurrence without clearing any previously set flags.
LLVM_ABI const SCEV *	evaluateAtIteration (const SCEV *It, ScalarEvolution &SE) const
	Return the value of this chain of recurrences at the specified iteration number.
LLVM_ABI const SCEV *	getNumIterationsInRange (const ConstantRange &Range, ScalarEvolution &SE) const
	Return the number of iterations of this loop that produce values in the specified constant range.
LLVM_ABI const SCEVAddRecExpr *	getPostIncExpr (ScalarEvolution &SE) const
	Return an expression representing the value of this expression one iteration of the loop ahead.
Public Member Functions inherited from llvm::SCEVNAryExpr
size_t	getNumOperands () const
const SCEV *	getOperand (unsigned i) const
ArrayRef< const SCEV * >	operands () const
NoWrapFlags	getNoWrapFlags (NoWrapFlags Mask=NoWrapMask) const
bool	hasNoUnsignedWrap () const
bool	hasNoSignedWrap () const
bool	hasNoSelfWrap () const
Public Member Functions inherited from llvm::SCEV
	SCEV (const FoldingSetNodeIDRef ID, SCEVTypes SCEVTy, unsigned short ExpressionSize)
	SCEV (const SCEV &)=delete
SCEV &	operator= (const SCEV &)=delete
SCEVTypes	getSCEVType () const
LLVM_ABI Type *	getType () const
	Return the LLVM type of this SCEV expression.
LLVM_ABI ArrayRef< const SCEV * >	operands () const
	Return operands of this SCEV expression.
LLVM_ABI bool	isZero () const
	Return true if the expression is a constant zero.
LLVM_ABI bool	isOne () const
	Return true if the expression is a constant one.
LLVM_ABI bool	isAllOnesValue () const
	Return true if the expression is a constant all-ones value.
LLVM_ABI bool	isNonConstantNegative () const
	Return true if the specified scev is negated, but not a constant.
unsigned short	getExpressionSize () const
LLVM_ABI void	print (raw_ostream &OS) const
	Print out the internal representation of this scalar to the specified stream.
LLVM_ABI 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)

Static Public Member Functions
static LLVM_ABI const SCEV *	evaluateAtIteration (ArrayRef< const SCEV * > Operands, const SCEV *It, ScalarEvolution &SE)
	Return the value of this chain of recurrences at the specified iteration number.
static bool	classof (const SCEV *S)
	Methods for support type inquiry through isa, cast, and dyn_cast:
Static Public Member Functions inherited from llvm::SCEVNAryExpr
static bool	classof (const SCEV *S)
	Methods for support type inquiry through isa, cast, and dyn_cast:

Friends
class	ScalarEvolution

Additional Inherited Members
Public Types inherited from llvm::SCEV
enum	NoWrapFlags { FlagAnyWrap = 0 , FlagNW = (1 << 0) , FlagNUW = (1 << 1) , FlagNSW = (1 << 2) , NoWrapMask = (1 << 3) - 1 }
	NoWrapFlags are bitfield indices into SubclassData. More...
Protected Member Functions inherited from llvm::SCEVNAryExpr
	SCEVNAryExpr (const FoldingSetNodeIDRef ID, enum SCEVTypes T, const SCEV const O, size_t N)
Protected Attributes inherited from llvm::SCEVNAryExpr
const SCEV const	Operands
size_t	NumOperands
Protected Attributes inherited from llvm::SCEV
const unsigned short	ExpressionSize
unsigned short	SubclassData = 0
	This field is initialized to zero and may be used in subclasses to store miscellaneous information.

Detailed Description

This node represents a polynomial recurrence on the trip count of the specified loop.

This is the primary focus of the ScalarEvolution framework; all the other SCEV subclasses are mostly just supporting infrastructure to allow SCEVAddRecExpr expressions to be created and analyzed.

All operands of an AddRec are required to be loop invariant.

Definition at line 348 of file ScalarEvolutionExpressions.h.

Member Function Documentation

◆ classof()

bool llvm::SCEVAddRecExpr::classof ( const SCEV * S )

inlinestatic

Methods for support type inquiry through isa, cast, and dyn_cast:

Definition at line 421 of file ScalarEvolutionExpressions.h.

References llvm::SCEV::getSCEVType(), and llvm::scAddRecExpr.

◆ evaluateAtIteration() [1/2]

const SCEV * SCEVAddRecExpr::evaluateAtIteration	(	ArrayRef< const SCEV * >	Operands,
		const SCEV *	It,
		ScalarEvolution &	SE )

static

Return the value of this chain of recurrences at the specified iteration number.

Takes an explicit list of operands to represent an AddRec.

Definition at line 986 of file ScalarEvolution.cpp.

References assert(), BinomialCoefficient(), llvm::ScalarEvolution::getAddExpr(), llvm::ScalarEvolution::getMulExpr(), llvm::isa(), llvm::SCEVNAryExpr::Operands, and ScalarEvolution.

◆ evaluateAtIteration() [2/2]

const SCEV * SCEVAddRecExpr::evaluateAtIteration	(	const SCEV *	It,
		ScalarEvolution &	SE ) const

Return the value of this chain of recurrences at the specified iteration number.

We can evaluate this recurrence by multiplying each element in the chain by the binomial coefficient corresponding to it. In other words, we can evaluate {A,+,B,+,C,+,D} as:

A*BC(It, 0) + B*BC(It, 1) + C*BC(It, 2) + D*BC(It, 3)

where BC(It, k) stands for binomial coefficient.

Definition at line 980 of file ScalarEvolution.cpp.

References evaluateAtIteration(), llvm::SCEVNAryExpr::operands(), and ScalarEvolution.

Referenced by countToEliminateCompares(), evaluateAtIteration(), EvaluateConstantChrecAtConstant(), genLoopLimit(), llvm::ScalarEvolution::getLoopInvariantExitCondDuringFirstIterationsImpl(), shouldPeelLastIteration(), and llvm::SCEVLoopAddRecRewriter::visitAddRecExpr().

◆ getLoop()

const Loop * llvm::SCEVAddRecExpr::getLoop ( ) const

inline

Definition at line 360 of file ScalarEvolutionExpressions.h.

◆ getNumIterationsInRange()

const SCEV * SCEVAddRecExpr::getNumIterationsInRange	(	const ConstantRange &	Range,
		ScalarEvolution &	SE ) const

Return the number of iterations of this loop that produce values in the specified constant range.

Another way of looking at this is that it returns the first iteration number where the value is not in the condition, thus computing the exit count. If the iteration count can't be computed, an instance of SCEVCouldNotCompute is returned.

Definition at line 13556 of file ScalarEvolution.cpp.

References A(), llvm::any_of(), assert(), llvm::BitWidth, llvm::cast(), llvm::dyn_cast(), EvaluateConstantChrecAtConstant(), llvm::SCEV::FlagNW, llvm::ScalarEvolution::getAddRecExpr(), llvm::ScalarEvolution::getConstant(), llvm::ScalarEvolution::getContext(), llvm::ScalarEvolution::getCouldNotCompute(), getLoop(), llvm::SCEVNAryExpr::getNoWrapFlags(), llvm::SCEVNAryExpr::getOperand(), getStart(), getType(), llvm::ScalarEvolution::getTypeSizeInBits(), llvm::ConstantInt::getValue(), llvm::ScalarEvolution::getZero(), llvm::isa(), isAffine(), isQuadratic(), llvm::SCEVNAryExpr::Operands, Operands, llvm::SCEVNAryExpr::operands(), Range, ScalarEvolution, and SolveQuadraticAddRecRange().