LLVM 19.0.0git
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llvm::RecurrenceDescriptor Class Reference

The RecurrenceDescriptor is used to identify recurrences variables in a loop. More...

#include "llvm/Analysis/IVDescriptors.h"

Classes

class  InstDesc
 This POD struct holds information about a potential recurrence operation. More...
 

Public Member Functions

 RecurrenceDescriptor ()=default
 
 RecurrenceDescriptor (Value *Start, Instruction *Exit, StoreInst *Store, RecurKind K, FastMathFlags FMF, Instruction *ExactFP, Type *RT, bool Signed, bool Ordered, SmallPtrSetImpl< Instruction * > &CI, unsigned MinWidthCastToRecurTy)
 
ValuegetRecurrenceIdentity (RecurKind K, Type *Tp, FastMathFlags FMF) const
 Returns identity corresponding to the RecurrenceKind.
 
RecurKind getRecurrenceKind () const
 
unsigned getOpcode () const
 
FastMathFlags getFastMathFlags () const
 
TrackingVH< ValuegetRecurrenceStartValue () const
 
InstructiongetLoopExitInstr () const
 
bool hasExactFPMath () const
 Returns true if the recurrence has floating-point math that requires precise (ordered) operations.
 
InstructiongetExactFPMathInst () const
 Returns 1st non-reassociative FP instruction in the PHI node's use-chain.
 
TypegetRecurrenceType () const
 Returns the type of the recurrence.
 
const SmallPtrSet< Instruction *, 8 > & getCastInsts () const
 Returns a reference to the instructions used for type-promoting the recurrence.
 
unsigned getMinWidthCastToRecurrenceTypeInBits () const
 Returns the minimum width used by the recurrence in bits.
 
bool isSigned () const
 Returns true if all source operands of the recurrence are SExtInsts.
 
bool isOrdered () const
 Expose an ordered FP reduction to the instance users.
 
SmallVector< Instruction *, 4 > getReductionOpChain (PHINode *Phi, Loop *L) const
 Attempts to find a chain of operations from Phi to LoopExitInst that can be treated as a set of reductions instructions for in-loop reductions.
 

Static Public Member Functions

static InstDesc isRecurrenceInstr (Loop *L, PHINode *Phi, Instruction *I, RecurKind Kind, InstDesc &Prev, FastMathFlags FuncFMF)
 Returns a struct describing if the instruction 'I' can be a recurrence variable of type 'Kind' for a Loop L and reduction PHI Phi.
 
static bool hasMultipleUsesOf (Instruction *I, SmallPtrSetImpl< Instruction * > &Insts, unsigned MaxNumUses)
 Returns true if instruction I has multiple uses in Insts.
 
static bool areAllUsesIn (Instruction *I, SmallPtrSetImpl< Instruction * > &Set)
 Returns true if all uses of the instruction I is within the Set.
 
static InstDesc isMinMaxPattern (Instruction *I, RecurKind Kind, const InstDesc &Prev)
 Returns a struct describing if the instruction is a llvm.
 
static InstDesc isAnyOfPattern (Loop *Loop, PHINode *OrigPhi, Instruction *I, InstDesc &Prev)
 Returns a struct describing whether the instruction is either a Select(ICmp(A, B), X, Y), or Select(FCmp(A, B), X, Y) where one of (X, Y) is a loop invariant integer and the other is a PHI value.
 
static InstDesc isConditionalRdxPattern (RecurKind Kind, Instruction *I)
 Returns a struct describing if the instruction is a Select(FCmp(X, Y), (Z = X op PHINode), PHINode) instruction pattern.
 
static unsigned getOpcode (RecurKind Kind)
 Returns the opcode corresponding to the RecurrenceKind.
 
static bool AddReductionVar (PHINode *Phi, RecurKind Kind, Loop *TheLoop, FastMathFlags FuncFMF, RecurrenceDescriptor &RedDes, DemandedBits *DB=nullptr, AssumptionCache *AC=nullptr, DominatorTree *DT=nullptr, ScalarEvolution *SE=nullptr)
 Returns true if Phi is a reduction of type Kind and adds it to the RecurrenceDescriptor.
 
static bool isReductionPHI (PHINode *Phi, Loop *TheLoop, RecurrenceDescriptor &RedDes, DemandedBits *DB=nullptr, AssumptionCache *AC=nullptr, DominatorTree *DT=nullptr, ScalarEvolution *SE=nullptr)
 Returns true if Phi is a reduction in TheLoop.
 
static bool isFixedOrderRecurrence (PHINode *Phi, Loop *TheLoop, DominatorTree *DT)
 Returns true if Phi is a fixed-order recurrence.
 
static bool isIntegerRecurrenceKind (RecurKind Kind)
 Returns true if the recurrence kind is an integer kind.
 
static bool isFloatingPointRecurrenceKind (RecurKind Kind)
 Returns true if the recurrence kind is a floating point kind.
 
static bool isIntMinMaxRecurrenceKind (RecurKind Kind)
 Returns true if the recurrence kind is an integer min/max kind.
 
static bool isFPMinMaxRecurrenceKind (RecurKind Kind)
 Returns true if the recurrence kind is a floating-point min/max kind.
 
static bool isMinMaxRecurrenceKind (RecurKind Kind)
 Returns true if the recurrence kind is any min/max kind.
 
static bool isAnyOfRecurrenceKind (RecurKind Kind)
 Returns true if the recurrence kind is of the form select(cmp(),x,y) where one of (x,y) is loop invariant.
 
static bool isFMulAddIntrinsic (Instruction *I)
 Returns true if the instruction is a call to the llvm.fmuladd intrinsic.
 

Public Attributes

StoreInstIntermediateStore = nullptr
 Reductions may store temporary or final result to an invariant address.
 

Detailed Description

The RecurrenceDescriptor is used to identify recurrences variables in a loop.

Reduction is a special case of recurrence that has uses of the recurrence variable outside the loop. The method isReductionPHI identifies reductions that are basic recurrences.

Basic recurrences are defined as the summation, product, OR, AND, XOR, min, or max of a set of terms. For example: for(i=0; i<n; i++) { total += array[i]; } is a summation of array elements. Basic recurrences are a special case of chains of recurrences (CR). See ScalarEvolution for CR references. This struct holds information about recurrence variables.

Definition at line 71 of file IVDescriptors.h.

Constructor & Destructor Documentation

◆ RecurrenceDescriptor() [1/2]

llvm::RecurrenceDescriptor::RecurrenceDescriptor ( )
default

◆ RecurrenceDescriptor() [2/2]

llvm::RecurrenceDescriptor::RecurrenceDescriptor ( Value Start,
Instruction Exit,
StoreInst Store,
RecurKind  K,
FastMathFlags  FMF,
Instruction ExactFP,
Type RT,
bool  Signed,
bool  Ordered,
SmallPtrSetImpl< Instruction * > &  CI,
unsigned  MinWidthCastToRecurTy 
)
inline

Member Function Documentation

◆ AddReductionVar()

bool RecurrenceDescriptor::AddReductionVar ( PHINode Phi,
RecurKind  Kind,
Loop TheLoop,
FastMathFlags  FuncFMF,
RecurrenceDescriptor RedDes,
DemandedBits DB = nullptr,
AssumptionCache AC = nullptr,
DominatorTree DT = nullptr,
ScalarEvolution SE = nullptr 
)
static

Returns true if Phi is a reduction of type Kind and adds it to the RecurrenceDescriptor.

If either DB is non-null or AC and DT are non-null, the minimal bit width needed to compute the reduction will be computed.

Definition at line 213 of file IVDescriptors.cpp.

References llvm::SmallVectorImpl< T >::append(), areAllUsesIn(), llvm::SmallVectorTemplateCommon< T, typename >::begin(), checkOrderedReduction(), collectCastInstrs(), computeRecurrenceType(), llvm::LoopBase< BlockT, LoopT >::contains(), llvm::SmallPtrSetImpl< PtrType >::count(), llvm::dbgs(), llvm::SmallVectorBase< Size_T >::empty(), llvm::SmallVectorTemplateCommon< T, typename >::end(), llvm::FAdd, llvm::FAnyOf, llvm::FMul, llvm::RecurrenceDescriptor::InstDesc::getExactFPMathInst(), llvm::FastMathFlags::getFast(), llvm::Instruction::getFastMathFlags(), llvm::LoopBase< BlockT, LoopT >::getHeader(), llvm::LoopBase< BlockT, LoopT >::getLoopPreheader(), llvm::User::getOperand(), llvm::Instruction::getParent(), llvm::RecurrenceDescriptor::InstDesc::getPatternInst(), llvm::StoreInst::getPointerOperand(), llvm::RecurrenceDescriptor::InstDesc::getRecKind(), llvm::ScalarEvolution::getSCEV(), llvm::StoreInst::getValueOperand(), hasMultipleUsesOf(), llvm::IAnyOf, llvm::SmallPtrSetImpl< PtrType >::insert(), IntermediateStore, llvm::is_contained(), isAnyOfPattern(), isAnyOfRecurrenceKind(), llvm::Instruction::isCommutative(), isConditionalRdxPattern(), isFloatingPointRecurrenceKind(), llvm::Type::isFloatingPointTy(), isFMulAddIntrinsic(), isFPMinMaxRecurrenceKind(), isIntegerRecurrenceKind(), llvm::Type::isIntegerTy(), isIntMinMaxRecurrenceKind(), llvm::ScalarEvolution::isLoopInvariant(), isMinMaxPattern(), isMinMaxRecurrenceKind(), llvm::RecurrenceDescriptor::InstDesc::isRecurrence(), isRecurrenceInstr(), LLVM_DEBUG, lookThroughAnd(), llvm::None, llvm::SmallVectorImpl< T >::pop_back_val(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::Value::use_empty(), and llvm::Value::users().

Referenced by isReductionPHI().

◆ areAllUsesIn()

bool RecurrenceDescriptor::areAllUsesIn ( Instruction I,
SmallPtrSetImpl< Instruction * > &  Set 
)
static

Returns true if all uses of the instruction I is within the Set.

Definition at line 32 of file IVDescriptors.cpp.

References llvm::SmallPtrSetImpl< PtrType >::count(), and I.

Referenced by AddReductionVar().

◆ getCastInsts()

const SmallPtrSet< Instruction *, 8 > & llvm::RecurrenceDescriptor::getCastInsts ( ) const
inline

Returns a reference to the instructions used for type-promoting the recurrence.

Definition at line 249 of file IVDescriptors.h.

Referenced by llvm::LoopVectorizationCostModel::collectValuesToIgnore().

◆ getExactFPMathInst()

Instruction * llvm::RecurrenceDescriptor::getExactFPMathInst ( ) const
inline

Returns 1st non-reassociative FP instruction in the PHI node's use-chain.

Definition at line 212 of file IVDescriptors.h.

Referenced by findInnerReductionPhi().

◆ getFastMathFlags()

FastMathFlags llvm::RecurrenceDescriptor::getFastMathFlags ( ) const
inline

◆ getLoopExitInstr()

Instruction * llvm::RecurrenceDescriptor::getLoopExitInstr ( ) const
inline

Definition at line 205 of file IVDescriptors.h.

Referenced by createAndCollectMergePhiForReduction().

◆ getMinWidthCastToRecurrenceTypeInBits()

unsigned llvm::RecurrenceDescriptor::getMinWidthCastToRecurrenceTypeInBits ( ) const
inline

Returns the minimum width used by the recurrence in bits.

Definition at line 252 of file IVDescriptors.h.

Referenced by llvm::LoopVectorizationCostModel::getSmallestAndWidestTypes().

◆ getOpcode() [1/2]

unsigned llvm::RecurrenceDescriptor::getOpcode ( ) const
inline

Definition at line 199 of file IVDescriptors.h.

References getOpcode(), and getRecurrenceKind().

Referenced by getOpcode(), and getReductionOpChain().

◆ getOpcode() [2/2]

unsigned RecurrenceDescriptor::getOpcode ( RecurKind  Kind)
static

◆ getRecurrenceIdentity()

Value * RecurrenceDescriptor::getRecurrenceIdentity ( RecurKind  K,
Type Tp,
FastMathFlags  FMF 
) const

◆ getRecurrenceKind()

RecurKind llvm::RecurrenceDescriptor::getRecurrenceKind ( ) const
inline

◆ getRecurrenceStartValue()

TrackingVH< Value > llvm::RecurrenceDescriptor::getRecurrenceStartValue ( ) const
inline

◆ getRecurrenceType()

Type * llvm::RecurrenceDescriptor::getRecurrenceType ( ) const
inline

◆ getReductionOpChain()

SmallVector< Instruction *, 4 > RecurrenceDescriptor::getReductionOpChain ( PHINode Phi,
Loop L 
) const

Attempts to find a chain of operations from Phi to LoopExitInst that can be treated as a set of reductions instructions for in-loop reductions.

Definition at line 1132 of file IVDescriptors.cpp.

References getOpcode(), llvm::Value::hasNUses(), isFMulAddIntrinsic(), llvm::SelectPatternResult::isMinOrMax(), LHS, llvm::matchSelectPattern(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), RHS, and llvm::Value::users().

Referenced by llvm::LoopVectorizationCostModel::collectInLoopReductions().

◆ hasExactFPMath()

bool llvm::RecurrenceDescriptor::hasExactFPMath ( ) const
inline

Returns true if the recurrence has floating-point math that requires precise (ordered) operations.

Definition at line 209 of file IVDescriptors.h.

Referenced by llvm::LoopVectorizationLegality::canVectorizeFPMath().

◆ hasMultipleUsesOf()

bool RecurrenceDescriptor::hasMultipleUsesOf ( Instruction I,
SmallPtrSetImpl< Instruction * > &  Insts,
unsigned  MaxNumUses 
)
static

Returns true if instruction I has multiple uses in Insts.

Definition at line 825 of file IVDescriptors.cpp.

References llvm::SmallPtrSetImpl< PtrType >::count(), and I.

Referenced by AddReductionVar().

◆ isAnyOfPattern()

RecurrenceDescriptor::InstDesc RecurrenceDescriptor::isAnyOfPattern ( Loop Loop,
PHINode OrigPhi,
Instruction I,
InstDesc Prev 
)
static

Returns a struct describing whether the instruction is either a Select(ICmp(A, B), X, Y), or Select(FCmp(A, B), X, Y) where one of (X, Y) is a loop invariant integer and the other is a PHI value.

Prev specifies the description of an already processed select instruction, so its corresponding cmp can be matched to it.

Definition at line 628 of file IVDescriptors.cpp.

References llvm::FAnyOf, llvm::RecurrenceDescriptor::InstDesc::getRecKind(), I, llvm::IAnyOf, llvm::Loop::isLoopInvariant(), llvm::PatternMatch::m_Cmp(), llvm::PatternMatch::m_OneUse(), llvm::PatternMatch::m_Select(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), and Select.

Referenced by AddReductionVar(), and isRecurrenceInstr().

◆ isAnyOfRecurrenceKind()

static bool llvm::RecurrenceDescriptor::isAnyOfRecurrenceKind ( RecurKind  Kind)
inlinestatic

Returns true if the recurrence kind is of the form select(cmp(),x,y) where one of (x,y) is loop invariant.

Definition at line 239 of file IVDescriptors.h.

References llvm::FAnyOf, and llvm::IAnyOf.

Referenced by AddReductionVar(), llvm::createAnyOfTargetReduction(), llvm::createTargetReduction(), llvm::VPReductionPHIRecipe::execute(), and isRecurrenceInstr().

◆ isConditionalRdxPattern()

RecurrenceDescriptor::InstDesc RecurrenceDescriptor::isConditionalRdxPattern ( RecurKind  Kind,
Instruction I 
)
static

Returns a struct describing if the instruction is a Select(FCmp(X, Y), (Z = X op PHINode), PHINode) instruction pattern.

Returns true if the select instruction has users in the compare-and-add reduction pattern below.

The select instruction argument is the last one in the sequence.

sum.1 = phi ... ... cmp = fcmp pred %0, CFP add = fadd %0, sum.1 sum.2 = select cmp, add, sum.1

Definition at line 724 of file IVDescriptors.cpp.

References llvm::Value::hasOneUse(), I, llvm::PatternMatch::m_Add(), llvm::PatternMatch::m_FAdd(), llvm::PatternMatch::m_FMul(), llvm::PatternMatch::m_FSub(), llvm::PatternMatch::m_Mul(), llvm::PatternMatch::m_Sub(), llvm::PatternMatch::m_Value(), and llvm::PatternMatch::match().

Referenced by AddReductionVar(), and isRecurrenceInstr().

◆ isFixedOrderRecurrence()

bool RecurrenceDescriptor::isFixedOrderRecurrence ( PHINode Phi,
Loop TheLoop,
DominatorTree DT 
)
static

Returns true if Phi is a fixed-order recurrence.

A fixed-order recurrence is a non-reduction recurrence relation in which the value of the recurrence in the current loop iteration equals a value defined in a previous iteration (e.g. if the value is defined in the previous iteration, we refer to it as first-order recurrence, if it is defined in the iteration before the previous, we refer to it as second-order recurrence and so on). Note that this function optimistically assumes that uses of the recurrence can be re-ordered if necessary and users need to check and perform the re-ordering.

Definition at line 948 of file IVDescriptors.cpp.

References llvm::LoopBase< BlockT, LoopT >::contains(), llvm::DominatorTree::dominates(), llvm::SmallVectorBase< Size_T >::empty(), llvm::LoopBase< BlockT, LoopT >::getHeader(), llvm::LoopBase< BlockT, LoopT >::getLoopLatch(), llvm::LoopBase< BlockT, LoopT >::getLoopPreheader(), llvm::SmallPtrSetImpl< PtrType >::insert(), llvm::SmallVectorImpl< T >::pop_back_val(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), and llvm::Value::users().

◆ isFloatingPointRecurrenceKind()

bool RecurrenceDescriptor::isFloatingPointRecurrenceKind ( RecurKind  Kind)
static

Returns true if the recurrence kind is a floating point kind.

Definition at line 60 of file IVDescriptors.cpp.

References isIntegerRecurrenceKind(), and llvm::None.

Referenced by AddReductionVar().

◆ isFMulAddIntrinsic()

static bool llvm::RecurrenceDescriptor::isFMulAddIntrinsic ( Instruction I)
inlinestatic

Returns true if the instruction is a call to the llvm.fmuladd intrinsic.

Definition at line 268 of file IVDescriptors.h.

References I.

Referenced by AddReductionVar(), checkOrderedReduction(), getReductionOpChain(), llvm::LoopVectorizationCostModel::getVectorCallCost(), isRecurrenceInstr(), and llvm::LoopVectorizationCostModel::setVectorizedCallDecision().

◆ isFPMinMaxRecurrenceKind()

static bool llvm::RecurrenceDescriptor::isFPMinMaxRecurrenceKind ( RecurKind  Kind)
inlinestatic

Returns true if the recurrence kind is a floating-point min/max kind.

Definition at line 227 of file IVDescriptors.h.

References llvm::FMax, llvm::FMaximum, llvm::FMin, and llvm::FMinimum.

Referenced by AddReductionVar(), isMinMaxRecurrenceKind(), and isRecurrenceInstr().

◆ isIntegerRecurrenceKind()

bool RecurrenceDescriptor::isIntegerRecurrenceKind ( RecurKind  Kind)
static

Returns true if the recurrence kind is an integer kind.

Definition at line 40 of file IVDescriptors.cpp.

References llvm::Add, llvm::And, llvm::FAnyOf, llvm::IAnyOf, llvm::Mul, llvm::Or, llvm::SMax, llvm::SMin, llvm::UMax, llvm::UMin, and llvm::Xor.

Referenced by AddReductionVar(), and isFloatingPointRecurrenceKind().

◆ isIntMinMaxRecurrenceKind()

static bool llvm::RecurrenceDescriptor::isIntMinMaxRecurrenceKind ( RecurKind  Kind)
inlinestatic

Returns true if the recurrence kind is an integer min/max kind.

Definition at line 221 of file IVDescriptors.h.

References llvm::SMax, llvm::SMin, llvm::UMax, and llvm::UMin.

Referenced by AddReductionVar(), isMinMaxRecurrenceKind(), and isRecurrenceInstr().

◆ isMinMaxPattern()

RecurrenceDescriptor::InstDesc RecurrenceDescriptor::isMinMaxPattern ( Instruction I,
RecurKind  Kind,
const InstDesc Prev 
)
static

◆ isMinMaxRecurrenceKind()

static bool llvm::RecurrenceDescriptor::isMinMaxRecurrenceKind ( RecurKind  Kind)
inlinestatic

◆ isOrdered()

bool llvm::RecurrenceDescriptor::isOrdered ( ) const
inline

Expose an ordered FP reduction to the instance users.

Definition at line 260 of file IVDescriptors.h.

Referenced by llvm::LoopVectorizationLegality::canVectorizeFPMath(), and llvm::LoopVectorizationCostModel::useOrderedReductions().

◆ isRecurrenceInstr()

RecurrenceDescriptor::InstDesc RecurrenceDescriptor::isRecurrenceInstr ( Loop L,
PHINode Phi,
Instruction I,
RecurKind  Kind,
InstDesc Prev,
FastMathFlags  FuncFMF 
)
static

Returns a struct describing if the instruction 'I' can be a recurrence variable of type 'Kind' for a Loop L and reduction PHI Phi.

If the recurrence is a min/max pattern of select(icmp()) this function advances the instruction pointer 'I' from the compare instruction to the select instruction and stores this pointer in 'PatternLastInst' member of the returned struct.

Definition at line 767 of file IVDescriptors.cpp.

References llvm::Add, llvm::And, assert(), llvm::FAdd, llvm::FMul, llvm::FMulAdd, llvm::RecurrenceDescriptor::InstDesc::getExactFPMathInst(), llvm::RecurrenceDescriptor::InstDesc::getRecKind(), I, isAnyOfPattern(), isAnyOfRecurrenceKind(), isConditionalRdxPattern(), isFMulAddIntrinsic(), isFPMinMaxRecurrenceKind(), isIntMinMaxRecurrenceKind(), isMinMaxPattern(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), llvm::Mul, llvm::FastMathFlags::noNaNs(), llvm::None, llvm::FastMathFlags::noSignedZeros(), llvm::Or, and llvm::Xor.

Referenced by AddReductionVar().

◆ isReductionPHI()

bool RecurrenceDescriptor::isReductionPHI ( PHINode Phi,
Loop TheLoop,
RecurrenceDescriptor RedDes,
DemandedBits DB = nullptr,
AssumptionCache AC = nullptr,
DominatorTree DT = nullptr,
ScalarEvolution SE = nullptr 
)
static

Returns true if Phi is a reduction in TheLoop.

The RecurrenceDescriptor is returned in RedDes. If either DB is non-null or AC and DT are non-null, the minimal bit width needed to compute the reduction will be computed. If SE is non-null, store instructions to loop invariant addresses are processed.

Definition at line 839 of file IVDescriptors.cpp.

References llvm::Add, AddReductionVar(), llvm::And, llvm::dbgs(), F, llvm::FAdd, llvm::FAnyOf, llvm::FMax, llvm::FMaximum, llvm::FMin, llvm::FMinimum, llvm::FMul, llvm::FMulAdd, llvm::LoopBase< BlockT, LoopT >::getHeader(), llvm::IAnyOf, LLVM_DEBUG, llvm::Mul, llvm::Or, llvm::FastMathFlags::setNoNaNs(), llvm::FastMathFlags::setNoSignedZeros(), llvm::SMax, llvm::SMin, llvm::UMax, llvm::UMin, and llvm::Xor.

Referenced by findInnerReductionPhi().

◆ isSigned()

bool llvm::RecurrenceDescriptor::isSigned ( ) const
inline

Returns true if all source operands of the recurrence are SExtInsts.

Definition at line 257 of file IVDescriptors.h.

Member Data Documentation

◆ IntermediateStore

StoreInst* llvm::RecurrenceDescriptor::IntermediateStore = nullptr

Reductions may store temporary or final result to an invariant address.

If there is such a store in the loop then, after successfull run of AddReductionVar method, this field will be assigned the last met store.

Definition at line 276 of file IVDescriptors.h.

Referenced by AddReductionVar(), llvm::LoopVectorizationLegality::isInvariantAddressOfReduction(), llvm::LoopVectorizationLegality::isInvariantStoreOfReduction(), and llvm::VPReductionRecipe::print().


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