diff options
Diffstat (limited to 'clang-r353983/include/llvm/Analysis/IVDescriptors.h')
| -rw-r--r-- | clang-r353983/include/llvm/Analysis/IVDescriptors.h | 356 |
1 files changed, 356 insertions, 0 deletions
diff --git a/clang-r353983/include/llvm/Analysis/IVDescriptors.h b/clang-r353983/include/llvm/Analysis/IVDescriptors.h new file mode 100644 index 00000000..254cabfc --- /dev/null +++ b/clang-r353983/include/llvm/Analysis/IVDescriptors.h @@ -0,0 +1,356 @@ +//===- llvm/Analysis/IVDescriptors.h - IndVar Descriptors -------*- C++ -*-===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This file "describes" induction and recurrence variables. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_ANALYSIS_IVDESCRIPTORS_H +#define LLVM_ANALYSIS_IVDESCRIPTORS_H + +#include "llvm/ADT/DenseMap.h" +#include "llvm/ADT/Optional.h" +#include "llvm/ADT/SetVector.h" +#include "llvm/ADT/SmallPtrSet.h" +#include "llvm/ADT/SmallVector.h" +#include "llvm/ADT/StringRef.h" +#include "llvm/Analysis/AliasAnalysis.h" +#include "llvm/Analysis/DemandedBits.h" +#include "llvm/Analysis/EHPersonalities.h" +#include "llvm/Analysis/MustExecute.h" +#include "llvm/Analysis/TargetTransformInfo.h" +#include "llvm/IR/Dominators.h" +#include "llvm/IR/IRBuilder.h" +#include "llvm/IR/InstrTypes.h" +#include "llvm/IR/Operator.h" +#include "llvm/IR/ValueHandle.h" +#include "llvm/Support/Casting.h" + +namespace llvm { + +class AliasSet; +class AliasSetTracker; +class BasicBlock; +class DataLayout; +class Loop; +class LoopInfo; +class OptimizationRemarkEmitter; +class PredicatedScalarEvolution; +class PredIteratorCache; +class ScalarEvolution; +class SCEV; +class TargetLibraryInfo; +class TargetTransformInfo; + +/// 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. +class RecurrenceDescriptor { +public: + /// This enum represents the kinds of recurrences that we support. + enum RecurrenceKind { + RK_NoRecurrence, ///< Not a recurrence. + RK_IntegerAdd, ///< Sum of integers. + RK_IntegerMult, ///< Product of integers. + RK_IntegerOr, ///< Bitwise or logical OR of numbers. + RK_IntegerAnd, ///< Bitwise or logical AND of numbers. + RK_IntegerXor, ///< Bitwise or logical XOR of numbers. + RK_IntegerMinMax, ///< Min/max implemented in terms of select(cmp()). + RK_FloatAdd, ///< Sum of floats. + RK_FloatMult, ///< Product of floats. + RK_FloatMinMax ///< Min/max implemented in terms of select(cmp()). + }; + + // This enum represents the kind of minmax recurrence. + enum MinMaxRecurrenceKind { + MRK_Invalid, + MRK_UIntMin, + MRK_UIntMax, + MRK_SIntMin, + MRK_SIntMax, + MRK_FloatMin, + MRK_FloatMax + }; + + RecurrenceDescriptor() = default; + + RecurrenceDescriptor(Value *Start, Instruction *Exit, RecurrenceKind K, + MinMaxRecurrenceKind MK, Instruction *UAI, Type *RT, + bool Signed, SmallPtrSetImpl<Instruction *> &CI) + : StartValue(Start), LoopExitInstr(Exit), Kind(K), MinMaxKind(MK), + UnsafeAlgebraInst(UAI), RecurrenceType(RT), IsSigned(Signed) { + CastInsts.insert(CI.begin(), CI.end()); + } + + /// This POD struct holds information about a potential recurrence operation. + class InstDesc { + public: + InstDesc(bool IsRecur, Instruction *I, Instruction *UAI = nullptr) + : IsRecurrence(IsRecur), PatternLastInst(I), MinMaxKind(MRK_Invalid), + UnsafeAlgebraInst(UAI) {} + + InstDesc(Instruction *I, MinMaxRecurrenceKind K, Instruction *UAI = nullptr) + : IsRecurrence(true), PatternLastInst(I), MinMaxKind(K), + UnsafeAlgebraInst(UAI) {} + + bool isRecurrence() { return IsRecurrence; } + + bool hasUnsafeAlgebra() { return UnsafeAlgebraInst != nullptr; } + + Instruction *getUnsafeAlgebraInst() { return UnsafeAlgebraInst; } + + MinMaxRecurrenceKind getMinMaxKind() { return MinMaxKind; } + + Instruction *getPatternInst() { return PatternLastInst; } + + private: + // Is this instruction a recurrence candidate. + bool IsRecurrence; + // The last instruction in a min/max pattern (select of the select(icmp()) + // pattern), or the current recurrence instruction otherwise. + Instruction *PatternLastInst; + // If this is a min/max pattern the comparison predicate. + MinMaxRecurrenceKind MinMaxKind; + // Recurrence has unsafe algebra. + Instruction *UnsafeAlgebraInst; + }; + + /// Returns a struct describing if the instruction 'I' can be a recurrence + /// variable of type 'Kind'. 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. + static InstDesc isRecurrenceInstr(Instruction *I, RecurrenceKind Kind, + InstDesc &Prev, bool HasFunNoNaNAttr); + + /// Returns true if instruction I has multiple uses in Insts + static bool hasMultipleUsesOf(Instruction *I, + SmallPtrSetImpl<Instruction *> &Insts, + unsigned MaxNumUses); + + /// Returns true if all uses of the instruction I is within the Set. + static bool areAllUsesIn(Instruction *I, SmallPtrSetImpl<Instruction *> &Set); + + /// Returns a struct describing if the instruction if the instruction is a + /// Select(ICmp(X, Y), X, Y) instruction pattern corresponding to a min(X, Y) + /// or max(X, Y). + static InstDesc isMinMaxSelectCmpPattern(Instruction *I, InstDesc &Prev); + + /// Returns a struct describing if the instruction is a + /// Select(FCmp(X, Y), (Z = X op PHINode), PHINode) instruction pattern. + static InstDesc isConditionalRdxPattern(RecurrenceKind Kind, Instruction *I); + + /// Returns identity corresponding to the RecurrenceKind. + static Constant *getRecurrenceIdentity(RecurrenceKind K, Type *Tp); + + /// Returns the opcode of binary operation corresponding to the + /// RecurrenceKind. + static unsigned getRecurrenceBinOp(RecurrenceKind Kind); + + /// Returns true if Phi is a reduction of type Kind and adds it to the + /// RecurrenceDescriptor. If either \p DB is non-null or \p AC and \p DT are + /// non-null, the minimal bit width needed to compute the reduction will be + /// computed. + static bool AddReductionVar(PHINode *Phi, RecurrenceKind Kind, Loop *TheLoop, + bool HasFunNoNaNAttr, + RecurrenceDescriptor &RedDes, + DemandedBits *DB = nullptr, + AssumptionCache *AC = nullptr, + DominatorTree *DT = nullptr); + + /// Returns true if Phi is a reduction in TheLoop. The RecurrenceDescriptor + /// is returned in RedDes. If either \p DB is non-null or \p AC and \p DT are + /// non-null, the minimal bit width needed to compute the reduction will be + /// computed. + static bool isReductionPHI(PHINode *Phi, Loop *TheLoop, + RecurrenceDescriptor &RedDes, + DemandedBits *DB = nullptr, + AssumptionCache *AC = nullptr, + DominatorTree *DT = nullptr); + + /// Returns true if Phi is a first-order recurrence. A first-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 the + /// previous iteration. \p SinkAfter includes pairs of instructions where the + /// first will be rescheduled to appear after the second if/when the loop is + /// vectorized. It may be augmented with additional pairs if needed in order + /// to handle Phi as a first-order recurrence. + static bool + isFirstOrderRecurrence(PHINode *Phi, Loop *TheLoop, + DenseMap<Instruction *, Instruction *> &SinkAfter, + DominatorTree *DT); + + RecurrenceKind getRecurrenceKind() { return Kind; } + + MinMaxRecurrenceKind getMinMaxRecurrenceKind() { return MinMaxKind; } + + TrackingVH<Value> getRecurrenceStartValue() { return StartValue; } + + Instruction *getLoopExitInstr() { return LoopExitInstr; } + + /// Returns true if the recurrence has unsafe algebra which requires a relaxed + /// floating-point model. + bool hasUnsafeAlgebra() { return UnsafeAlgebraInst != nullptr; } + + /// Returns first unsafe algebra instruction in the PHI node's use-chain. + Instruction *getUnsafeAlgebraInst() { return UnsafeAlgebraInst; } + + /// Returns true if the recurrence kind is an integer kind. + static bool isIntegerRecurrenceKind(RecurrenceKind Kind); + + /// Returns true if the recurrence kind is a floating point kind. + static bool isFloatingPointRecurrenceKind(RecurrenceKind Kind); + + /// Returns true if the recurrence kind is an arithmetic kind. + static bool isArithmeticRecurrenceKind(RecurrenceKind Kind); + + /// Returns the type of the recurrence. This type can be narrower than the + /// actual type of the Phi if the recurrence has been type-promoted. + Type *getRecurrenceType() { return RecurrenceType; } + + /// Returns a reference to the instructions used for type-promoting the + /// recurrence. + SmallPtrSet<Instruction *, 8> &getCastInsts() { return CastInsts; } + + /// Returns true if all source operands of the recurrence are SExtInsts. + bool isSigned() { return IsSigned; } + +private: + // The starting value of the recurrence. + // It does not have to be zero! + TrackingVH<Value> StartValue; + // The instruction who's value is used outside the loop. + Instruction *LoopExitInstr = nullptr; + // The kind of the recurrence. + RecurrenceKind Kind = RK_NoRecurrence; + // If this a min/max recurrence the kind of recurrence. + MinMaxRecurrenceKind MinMaxKind = MRK_Invalid; + // First occurrence of unasfe algebra in the PHI's use-chain. + Instruction *UnsafeAlgebraInst = nullptr; + // The type of the recurrence. + Type *RecurrenceType = nullptr; + // True if all source operands of the recurrence are SExtInsts. + bool IsSigned = false; + // Instructions used for type-promoting the recurrence. + SmallPtrSet<Instruction *, 8> CastInsts; +}; + +/// A struct for saving information about induction variables. +class InductionDescriptor { +public: + /// This enum represents the kinds of inductions that we support. + enum InductionKind { + IK_NoInduction, ///< Not an induction variable. + IK_IntInduction, ///< Integer induction variable. Step = C. + IK_PtrInduction, ///< Pointer induction var. Step = C / sizeof(elem). + IK_FpInduction ///< Floating point induction variable. + }; + +public: + /// Default constructor - creates an invalid induction. + InductionDescriptor() = default; + + /// Get the consecutive direction. Returns: + /// 0 - unknown or non-consecutive. + /// 1 - consecutive and increasing. + /// -1 - consecutive and decreasing. + int getConsecutiveDirection() const; + + Value *getStartValue() const { return StartValue; } + InductionKind getKind() const { return IK; } + const SCEV *getStep() const { return Step; } + BinaryOperator *getInductionBinOp() const { return InductionBinOp; } + ConstantInt *getConstIntStepValue() const; + + /// Returns true if \p Phi is an induction in the loop \p L. If \p Phi is an + /// induction, the induction descriptor \p D will contain the data describing + /// this induction. If by some other means the caller has a better SCEV + /// expression for \p Phi than the one returned by the ScalarEvolution + /// analysis, it can be passed through \p Expr. If the def-use chain + /// associated with the phi includes casts (that we know we can ignore + /// under proper runtime checks), they are passed through \p CastsToIgnore. + static bool + isInductionPHI(PHINode *Phi, const Loop *L, ScalarEvolution *SE, + InductionDescriptor &D, const SCEV *Expr = nullptr, + SmallVectorImpl<Instruction *> *CastsToIgnore = nullptr); + + /// Returns true if \p Phi is a floating point induction in the loop \p L. + /// If \p Phi is an induction, the induction descriptor \p D will contain + /// the data describing this induction. + static bool isFPInductionPHI(PHINode *Phi, const Loop *L, ScalarEvolution *SE, + InductionDescriptor &D); + + /// Returns true if \p Phi is a loop \p L induction, in the context associated + /// with the run-time predicate of PSE. If \p Assume is true, this can add + /// further SCEV predicates to \p PSE in order to prove that \p Phi is an + /// induction. + /// If \p Phi is an induction, \p D will contain the data describing this + /// induction. + static bool isInductionPHI(PHINode *Phi, const Loop *L, + PredicatedScalarEvolution &PSE, + InductionDescriptor &D, bool Assume = false); + + /// Returns true if the induction type is FP and the binary operator does + /// not have the "fast-math" property. Such operation requires a relaxed FP + /// mode. + bool hasUnsafeAlgebra() { + return InductionBinOp && !cast<FPMathOperator>(InductionBinOp)->isFast(); + } + + /// Returns induction operator that does not have "fast-math" property + /// and requires FP unsafe mode. + Instruction *getUnsafeAlgebraInst() { + if (!InductionBinOp || cast<FPMathOperator>(InductionBinOp)->isFast()) + return nullptr; + return InductionBinOp; + } + + /// Returns binary opcode of the induction operator. + Instruction::BinaryOps getInductionOpcode() const { + return InductionBinOp ? InductionBinOp->getOpcode() + : Instruction::BinaryOpsEnd; + } + + /// Returns a reference to the type cast instructions in the induction + /// update chain, that are redundant when guarded with a runtime + /// SCEV overflow check. + const SmallVectorImpl<Instruction *> &getCastInsts() const { + return RedundantCasts; + } + +private: + /// Private constructor - used by \c isInductionPHI. + InductionDescriptor(Value *Start, InductionKind K, const SCEV *Step, + BinaryOperator *InductionBinOp = nullptr, + SmallVectorImpl<Instruction *> *Casts = nullptr); + + /// Start value. + TrackingVH<Value> StartValue; + /// Induction kind. + InductionKind IK = IK_NoInduction; + /// Step value. + const SCEV *Step = nullptr; + // Instruction that advances induction variable. + BinaryOperator *InductionBinOp = nullptr; + // Instructions used for type-casts of the induction variable, + // that are redundant when guarded with a runtime SCEV overflow check. + SmallVector<Instruction *, 2> RedundantCasts; +}; + +} // end namespace llvm + +#endif // LLVM_ANALYSIS_IVDESCRIPTORS_H |