LLVM 19.0.0git
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llvm::SCEVAddRecExpr Class Reference

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:
Inheritance graph
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Public Member Functions

TypegetType () const
 
const SCEVgetStart () const
 
const LoopgetLoop () const
 
const SCEVgetStepRecurrence (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 + B*x + C*x^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.
 
const SCEVevaluateAtIteration (const SCEV *It, ScalarEvolution &SE) const
 Return the value of this chain of recurrences at the specified iteration number.
 
const SCEVgetNumIterationsInRange (const ConstantRange &Range, ScalarEvolution &SE) const
 Return the number of iterations of this loop that produce values in the specified constant range.
 
const SCEVAddRecExprgetPostIncExpr (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 SCEVgetOperand (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
 
SCEVoperator= (const SCEV &)=delete
 
SCEVTypes getSCEVType () const
 
TypegetType () 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)
 

Static Public Member Functions

static const SCEVevaluateAtIteration (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 *constOperands
 
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 347 of file ScalarEvolutionExpressions.h.

Member Function Documentation

◆ classof()

static bool llvm::SCEVAddRecExpr::classof ( const SCEV S)
inlinestatic

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

Definition at line 418 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 985 of file ScalarEvolution.cpp.

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

◆ 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 979 of file ScalarEvolution.cpp.

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

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

◆ getLoop()

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

◆ 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 13245 of file ScalarEvolution.cpp.

References A, llvm::any_of(), assert(), llvm::BitWidth, End, EvaluateConstantChrecAtConstant(), llvm::ScalarEvolution::getAddRecExpr(), llvm::ScalarEvolution::getConstant(), llvm::ScalarEvolution::getContext(), llvm::ScalarEvolution::getCouldNotCompute(), getType(), llvm::ScalarEvolution::getTypeSizeInBits(), llvm::ConstantInt::getValue(), llvm::ScalarEvolution::getZero(), Operands, and SolveQuadraticAddRecRange().

◆ getPostIncExpr()

const SCEVAddRecExpr * SCEVAddRecExpr::getPostIncExpr ( ScalarEvolution SE) const

Return an expression representing the value of this expression one iteration of the loop ahead.

Definition at line 13317 of file ScalarEvolution.cpp.

References assert(), llvm::SCEV::FlagAnyWrap, llvm::ScalarEvolution::getAddExpr(), llvm::ScalarEvolution::getAddRecExpr(), llvm::Last, and llvm::SmallVectorTemplateBase< T, bool >::push_back().

Referenced by canFoldTermCondOfLoop(), and genLoopLimit().

◆ getStart()

const SCEV * llvm::SCEVAddRecExpr::getStart ( ) const
inline

◆ getStepRecurrence()

const SCEV * llvm::SCEVAddRecExpr::getStepRecurrence ( ScalarEvolution SE) const
inline

◆ getType()

Type * llvm::SCEVAddRecExpr::getType ( ) const
inline

◆ isAffine()

bool llvm::SCEVAddRecExpr::isAffine ( ) const
inline

◆ isQuadratic()

bool llvm::SCEVAddRecExpr::isQuadratic ( ) const
inline

Return true if this represents an expression A + B*x + C*x^2 where A, B and C are loop invariant values.

This corresponds to an addrec of the form {L,+,M,+,N}

Definition at line 384 of file ScalarEvolutionExpressions.h.

References llvm::SCEVNAryExpr::getNumOperands().

◆ setNoWrapFlags()

void llvm::SCEVAddRecExpr::setNoWrapFlags ( NoWrapFlags  Flags)
inline

Set flags for a recurrence without clearing any previously set flags.

For AddRec, either NUW or NSW implies NW. Keep track of this fact here to make it easier to propagate flags.

Definition at line 389 of file ScalarEvolutionExpressions.h.

References llvm::SCEV::FlagNSW, llvm::SCEV::FlagNUW, llvm::SCEV::FlagNW, llvm::ScalarEvolution::setFlags(), and llvm::SCEV::SubclassData.

Referenced by llvm::ScalarEvolution::setNoWrapFlags().

Friends And Related Function Documentation

◆ ScalarEvolution

friend class ScalarEvolution
friend

Definition at line 348 of file ScalarEvolutionExpressions.h.


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