ARMTargetTransformInfo.h

Go to the documentation of this file.

//===- ARMTargetTransformInfo.h - ARM specific TTI --------------*- 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
//
//===----------------------------------------------------------------------===//
//
/// \file
/// This file a TargetTransformInfoImplBase conforming object specific to the
/// ARM target machine. It uses the target's detailed information to
/// provide more precise answers to certain TTI queries, while letting the
/// target independent and default TTI implementations handle the rest.
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_LIB_TARGET_ARM_ARMTARGETTRANSFORMINFO_H
#define LLVM_LIB_TARGET_ARM_ARMTARGETTRANSFORMINFO_H
 
#include "ARM.h"
#include "ARMSubtarget.h"
#include "ARMTargetMachine.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/CodeGen/BasicTTIImpl.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/Function.h"
#include "llvm/TargetParser/SubtargetFeature.h"
#include <optional>
 
namespace llvm {
 
class APInt;
class ARMTargetLowering;
class Instruction;
class Loop;
class SCEV;
class ScalarEvolution;
class Type;
class Value;
 
namespace TailPredication {
enum Mode {
  Disabled = 0,
  EnabledNoReductions,
  Enabled,
  ForceEnabledNoReductions,
  ForceEnabled
};
}
 
// For controlling conversion of memcpy into Tail Predicated loop.
namespace TPLoop {
enum MemTransfer { ForceDisabled = 0, ForceEnabled, Allow };
}
 
class ARMTTIImpl final : public BasicTTIImplBase<ARMTTIImpl> {
  using BaseT = BasicTTIImplBase<ARMTTIImpl>;
  using TTI = TargetTransformInfo;
 
  friend BaseT;
 
  const ARMSubtarget *ST;
  const ARMTargetLowering *TLI;
 
  const ARMSubtarget *getST() const { return ST; }
  const ARMTargetLowering *getTLI() const { return TLI; }
 
public:
  explicit ARMTTIImpl(const ARMBaseTargetMachine *TM, const Function &F)
      : BaseT(TM, F.getDataLayout()), ST(TM->getSubtargetImpl(F)),
        TLI(ST->getTargetLowering()) {}
 
  bool enableInterleavedAccessVectorization() const override { return true; }
 
  TTI::AddressingModeKind
  getPreferredAddressingMode(const Loop *L, ScalarEvolution *SE) const override;
 
  /// Floating-point computation using ARMv8 AArch32 Advanced
  /// SIMD instructions remains unchanged from ARMv7. Only AArch64 SIMD
  /// and Arm MVE are IEEE-754 compliant.
  bool isFPVectorizationPotentiallyUnsafe() const override {
    return !ST->isTargetDarwin() && !ST->hasMVEFloatOps();
  }
 
  std::optional<Instruction *>
  instCombineIntrinsic(InstCombiner &IC, IntrinsicInst &II) const override;
  std::optional<Value *> simplifyDemandedVectorEltsIntrinsic(
      InstCombiner &IC, IntrinsicInst &II, APInt DemandedElts, APInt &UndefElts,
      APInt &UndefElts2, APInt &UndefElts3,
      std::function<void(Instruction *, unsigned, APInt, APInt &)>
          SimplifyAndSetOp) const override;
 
  /// \name Scalar TTI Implementations
  /// @{
 
  InstructionCost getIntImmCodeSizeCost(unsigned Opcode, unsigned Idx,
                                        const APInt &Imm,
                                        Type *Ty) const override;
 
  using BaseT::getIntImmCost;
  InstructionCost getIntImmCost(const APInt &Imm, Type *Ty,
                                TTI::TargetCostKind CostKind) const override;
 
  InstructionCost getIntImmCostInst(unsigned Opcode, unsigned Idx,
                                    const APInt &Imm, Type *Ty,
                                    TTI::TargetCostKind CostKind,
                                    Instruction *Inst = nullptr) const override;
 
  /// @}
 
  /// \name Vector TTI Implementations
  /// @{
 
  unsigned getNumberOfRegisters(unsigned ClassID) const override {
    bool Vector = (ClassID == 1);
    if (Vector) {
      if (ST->hasNEON())
        return 16;
      if (ST->hasMVEIntegerOps())
        return 8;
      return 0;
    }
 
    if (ST->isThumb1Only())
      return 8;
    return 13;
  }
 
  TypeSize
  getRegisterBitWidth(TargetTransformInfo::RegisterKind K) const override {
    switch (K) {
    case TargetTransformInfo::RGK_Scalar:
      return TypeSize::getFixed(32);
    case TargetTransformInfo::RGK_FixedWidthVector:
      if (ST->hasNEON())
        return TypeSize::getFixed(128);
      if (ST->hasMVEIntegerOps())
        return TypeSize::getFixed(128);
      return TypeSize::getFixed(0);
    case TargetTransformInfo::RGK_ScalableVector:
      return TypeSize::getScalable(0);
    }
    llvm_unreachable("Unsupported register kind");
  }
 
  unsigned getMaxInterleaveFactor(ElementCount VF,
                                  bool HasUnorderedReductions) const override {
    return ST->getMaxInterleaveFactor();
  }
 
  bool isProfitableLSRChainElement(Instruction *I) const override;
 
  bool
  isLegalMaskedLoad(Type *DataTy, Align Alignment, unsigned AddressSpace,
                    TTI::MaskKind MaskKind =
                        TTI::MaskKind::VariableOrConstantMask) const override;
 
  bool
  isLegalMaskedStore(Type *DataTy, Align Alignment, unsigned AddressSpace,
                     TTI::MaskKind MaskKind =
                         TTI::MaskKind::VariableOrConstantMask) const override {
    return isLegalMaskedLoad(DataTy, Alignment, AddressSpace, MaskKind);
  }
 
  bool forceScalarizeMaskedGather(VectorType *VTy,
                                  Align Alignment) const override {
    // For MVE, we have a custom lowering pass that will already have custom
    // legalised any gathers that we can lower to MVE intrinsics, and want to
    // expand all the rest. The pass runs before the masked intrinsic lowering
    // pass.
    return true;
  }
 
  bool forceScalarizeMaskedScatter(VectorType *VTy,
                                   Align Alignment) const override {
    return forceScalarizeMaskedGather(VTy, Alignment);
  }
 
  bool isLegalMaskedGather(Type *Ty, Align Alignment) const override;
 
  bool isLegalMaskedScatter(Type *Ty, Align Alignment) const override {
    return isLegalMaskedGather(Ty, Alignment);
  }
 
  InstructionCost getMemcpyCost(const Instruction *I) const override;
 
  uint64_t getMaxMemIntrinsicInlineSizeThreshold() const override {
    return ST->getMaxInlineSizeThreshold();
  }
 
  int getNumMemOps(const IntrinsicInst *I) const;
 
  InstructionCost
  getShuffleCost(TTI::ShuffleKind Kind, VectorType *DstTy, VectorType *SrcTy,
                 TTI::TargetCostKind CostKind, ArrayRef<int> Mask, int Index,
                 VectorType *SubTp, ArrayRef<const Value *> Args = {},
                 const Instruction *CtxI = nullptr,
                 TTI::VectorInstrContext VIC =
                     TTI::VectorInstrContext::None) const override;
 
  bool preferInLoopReduction(RecurKind Kind, Type *Ty) const override;
 
  bool preferPredicatedReductionSelect() const override;
 
  bool shouldExpandReduction(const IntrinsicInst *II) const override {
    return false;
  }
 
  InstructionCost getCFInstrCost(unsigned Opcode, TTI::TargetCostKind CostKind,
                                 const Instruction *I = nullptr) const override;
 
  InstructionCost
  getCastInstrCost(unsigned Opcode, Type *Dst, Type *Src,
                   TTI::CastContextHint CCH, TTI::TargetCostKind CostKind,
                   const Instruction *I = nullptr) const override;
 
  InstructionCost getCmpSelInstrCost(
      unsigned Opcode, Type *ValTy, Type *CondTy, CmpInst::Predicate VecPred,
      TTI::TargetCostKind CostKind,
      TTI::OperandValueInfo Op1Info = {TTI::OK_AnyValue, TTI::OP_None},
      TTI::OperandValueInfo Op2Info = {TTI::OK_AnyValue, TTI::OP_None},
      const Instruction *I = nullptr) const override;
 
  using BaseT::getVectorInstrCost;
  InstructionCost
  getVectorInstrCost(unsigned Opcode, Type *Ty, TTI::TargetCostKind CostKind,
                     unsigned Index, const Value *Op0, const Value *Op1,
                     TTI::VectorInstrContext VIC =
                         TTI::VectorInstrContext::None) const override;
 
  InstructionCost
  getAddressComputationCost(Type *Ty, ScalarEvolution *SE, const SCEV *Ptr,
                            TTI::TargetCostKind CostKind) const override;
 
  InstructionCost getArithmeticInstrCost(
      unsigned Opcode, Type *Ty, TTI::TargetCostKind CostKind,
      TTI::OperandValueInfo Op1Info = {TTI::OK_AnyValue, TTI::OP_None},
      TTI::OperandValueInfo Op2Info = {TTI::OK_AnyValue, TTI::OP_None},
      ArrayRef<const Value *> Args = {},
      const Instruction *CtxI = nullptr) const override;
 
  InstructionCost getMemoryOpCost(
      unsigned Opcode, Type *Src, Align Alignment, unsigned AddressSpace,
      TTI::TargetCostKind CostKind,
      TTI::OperandValueInfo OpInfo = {TTI::OK_AnyValue, TTI::OP_None},
      const Instruction *I = nullptr) const override;
 
  InstructionCost
  getMemIntrinsicInstrCost(const MemIntrinsicCostAttributes &MICA,
                           TTI::TargetCostKind CostKind) const override;
 
  InstructionCost getMaskedMemoryOpCost(const MemIntrinsicCostAttributes &MICA,
                                        TTI::TargetCostKind CostKind) const;
 
  InstructionCost getInterleavedMemoryOpCost(
      unsigned Opcode, Type *VecTy, unsigned Factor, ArrayRef<unsigned> Indices,
      Align Alignment, unsigned AddressSpace, TTI::TargetCostKind CostKind,
      bool UseMaskForCond = false, bool UseMaskForGaps = false) const override;
 
  InstructionCost getGatherScatterOpCost(const MemIntrinsicCostAttributes &MICA,
                                         TTI::TargetCostKind CostKind) const;
 
  InstructionCost
  getArithmeticReductionCost(unsigned Opcode, VectorType *ValTy,
                             std::optional<FastMathFlags> FMF,
                             TTI::TargetCostKind CostKind) const override;
  InstructionCost
  getExtendedReductionCost(unsigned Opcode, bool IsUnsigned, Type *ResTy,
                           VectorType *ValTy, std::optional<FastMathFlags> FMF,
                           TTI::TargetCostKind CostKind) const override;
  InstructionCost
  getMulAccReductionCost(bool IsUnsigned, unsigned RedOpcode, Type *ResTy,
                         VectorType *ValTy,
                         TTI::TargetCostKind CostKind) const override;
 
  InstructionCost
  getMinMaxReductionCost(Intrinsic::ID IID, VectorType *Ty, FastMathFlags FMF,
                         TTI::TargetCostKind CostKind) const override;
 
  InstructionCost
  getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
                        TTI::TargetCostKind CostKind) const override;
 
  InstructionCost getPartialReductionCost(
      unsigned Opcode, Type *InputTypeA, Type *InputTypeB, Type *AccumType,
      ElementCount VF, TTI::PartialReductionExtendKind OpAExtend,
      TTI::PartialReductionExtendKind OpBExtend, std::optional<unsigned> BinOp,
      TTI::TargetCostKind CostKind,
      std::optional<FastMathFlags> FMF) const override {
    return InstructionCost::getInvalid();
  }
 
  /// getScalingFactorCost - Return the cost of the scaling used in
  /// addressing mode represented by AM.
  /// If the AM is supported, the return value must be >= 0.
  /// If the AM is not supported, the return value is an invalid cost.
  InstructionCost getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
                                       StackOffset BaseOffset, bool HasBaseReg,
                                       int64_t Scale,
                                       unsigned AddrSpace) const override;
 
  bool maybeLoweredToCall(Instruction &I) const;
  bool isLoweredToCall(const Function *F) const override;
  bool isHardwareLoopProfitable(Loop *L, ScalarEvolution &SE,
                                AssumptionCache &AC, TargetLibraryInfo *LibInfo,
                                HardwareLoopInfo &HWLoopInfo) const override;
  bool preferTailFoldingOverEpilogue(TailFoldingInfo *TFI) const override;
  void getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
                               TTI::UnrollingPreferences &UP,
                               OptimizationRemarkEmitter *ORE) const override;
 
  TailFoldingStyle getPreferredTailFoldingStyle() const override;
 
  void getPeelingPreferences(Loop *L, ScalarEvolution &SE,
                             TTI::PeelingPreferences &PP) const override;
  bool shouldBuildLookupTablesForConstant(Constant *C) const override {
    // In the ROPI and RWPI relocation models we can't have pointers to global
    // variables or functions in constant data, so don't convert switches to
    // lookup tables if any of the values would need relocation.
    if (ST->isROPI() || ST->isRWPI())
      return !C->needsDynamicRelocation();
 
    return true;
  }
 
  bool shouldConsiderVectorizationRegPressure() const override;
 
  bool hasArmWideBranch(bool Thumb) const override;
 
  bool isProfitableToSinkOperands(Instruction *I,
                                  SmallVectorImpl<Use *> &Ops) const override;
 
  unsigned getNumBytesToPadGlobalArray(unsigned Size,
                                       Type *ArrayType) const override;
 
  /// @}
};
 
/// isVREVMask - Check if a vector shuffle corresponds to a VREV
/// instruction with the specified blocksize.  (The order of the elements
/// within each block of the vector is reversed.)
inline bool isVREVMask(ArrayRef<int> M, EVT VT, unsigned BlockSize) {
  assert((BlockSize == 16 || BlockSize == 32 || BlockSize == 64) &&
         "Only possible block sizes for VREV are: 16, 32, 64");
 
  unsigned EltSz = VT.getScalarSizeInBits();
  if (EltSz != 8 && EltSz != 16 && EltSz != 32)
    return false;
 
  unsigned BlockElts = M[0] + 1;
  // If the first shuffle index is UNDEF, be optimistic.
  if (M[0] < 0)
    BlockElts = BlockSize / EltSz;
 
  if (BlockSize <= EltSz || BlockSize != BlockElts * EltSz)
    return false;
 
  for (unsigned i = 0, e = M.size(); i < e; ++i) {
    if (M[i] < 0)
      continue; // ignore UNDEF indices
    if ((unsigned)M[i] != (i - i % BlockElts) + (BlockElts - 1 - i % BlockElts))
      return false;
  }
 
  return true;
}
 
} // end namespace llvm
 
#endif // LLVM_LIB_TARGET_ARM_ARMTARGETTRANSFORMINFO_H