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//===- AArch64TargetTransformInfo.h - AArch64 specific TTI ------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
/// \file
/// This file a TargetTransformInfo::Concept conforming object specific to the
/// AArch64 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.
#include "AArch64.h"
#include "AArch64Subtarget.h"
#include "AArch64TargetMachine.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/CodeGen/BasicTTIImpl.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Intrinsics.h"
#include <cstdint>
#include <optional>
namespace llvm {
class APInt;
class Instruction;
class IntrinsicInst;
class Loop;
class SCEV;
class ScalarEvolution;
class Type;
class Value;
class VectorType;
class AArch64TTIImpl : public BasicTTIImplBase<AArch64TTIImpl> {
using BaseT = BasicTTIImplBase<AArch64TTIImpl>;
using TTI = TargetTransformInfo;
friend BaseT;
const AArch64Subtarget *ST;
const AArch64TargetLowering *TLI;
const AArch64Subtarget *getST() const { return ST; }
const AArch64TargetLowering *getTLI() const { return TLI; }
enum MemIntrinsicType {
bool isWideningInstruction(Type *DstTy, unsigned Opcode,
ArrayRef<const Value *> Args,
Type *SrcOverrideTy = nullptr);
// A helper function called by 'getVectorInstrCost'.
// 'Val' and 'Index' are forwarded from 'getVectorInstrCost'; 'HasRealUse'
// indicates whether the vector instruction is available in the input IR or
// just imaginary in vectorizer passes.
InstructionCost getVectorInstrCostHelper(const Instruction *I, Type *Val,
unsigned Index, bool HasRealUse);
explicit AArch64TTIImpl(const AArch64TargetMachine *TM, const Function &F)
: BaseT(TM, F.getParent()->getDataLayout()), ST(TM->getSubtargetImpl(F)),
TLI(ST->getTargetLowering()) {}
bool areInlineCompatible(const Function *Caller,
const Function *Callee) const;
/// \name Scalar TTI Implementations
/// @{
using BaseT::getIntImmCost;
InstructionCost getIntImmCost(int64_t Val);
InstructionCost getIntImmCost(const APInt &Imm, Type *Ty,
TTI::TargetCostKind CostKind);
InstructionCost getIntImmCostInst(unsigned Opcode, unsigned Idx,
const APInt &Imm, Type *Ty,
TTI::TargetCostKind CostKind,
Instruction *Inst = nullptr);
InstructionCost getIntImmCostIntrin(Intrinsic::ID IID, unsigned Idx,
const APInt &Imm, Type *Ty,
TTI::TargetCostKind CostKind);
TTI::PopcntSupportKind getPopcntSupport(unsigned TyWidth);
/// @}
/// \name Vector TTI Implementations
/// @{
bool enableInterleavedAccessVectorization() { return true; }
bool enableMaskedInterleavedAccessVectorization() { return ST->hasSVE(); }
unsigned getNumberOfRegisters(unsigned ClassID) const {
bool Vector = (ClassID == 1);
if (Vector) {
if (ST->hasNEON())
return 32;
return 0;
return 31;
InstructionCost getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
TTI::TargetCostKind CostKind);
std::optional<Instruction *> instCombineIntrinsic(InstCombiner &IC,
IntrinsicInst &II) const;
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;
TypeSize getRegisterBitWidth(TargetTransformInfo::RegisterKind K) const;
unsigned getMinVectorRegisterBitWidth() const {
return ST->getMinVectorRegisterBitWidth();
std::optional<unsigned> getVScaleForTuning() const {
return ST->getVScaleForTuning();
bool isVScaleKnownToBeAPowerOfTwo() const { return true; }
bool shouldMaximizeVectorBandwidth(TargetTransformInfo::RegisterKind K) const;
/// Try to return an estimate cost factor that can be used as a multiplier
/// when scalarizing an operation for a vector with ElementCount \p VF.
/// For scalable vectors this currently takes the most pessimistic view based
/// upon the maximum possible value for vscale.
unsigned getMaxNumElements(ElementCount VF) const {
if (!VF.isScalable())
return VF.getFixedValue();
return VF.getKnownMinValue() * ST->getVScaleForTuning();
unsigned getMaxInterleaveFactor(ElementCount VF);
bool prefersVectorizedAddressing() const;
InstructionCost getMaskedMemoryOpCost(unsigned Opcode, Type *Src,
Align Alignment, unsigned AddressSpace,
TTI::TargetCostKind CostKind);
InstructionCost getGatherScatterOpCost(unsigned Opcode, Type *DataTy,
const Value *Ptr, bool VariableMask,
Align Alignment,
TTI::TargetCostKind CostKind,
const Instruction *I = nullptr);
bool isExtPartOfAvgExpr(const Instruction *ExtUser, Type *Dst, Type *Src);
InstructionCost getCastInstrCost(unsigned Opcode, Type *Dst, Type *Src,
TTI::CastContextHint CCH,
TTI::TargetCostKind CostKind,
const Instruction *I = nullptr);
InstructionCost getExtractWithExtendCost(unsigned Opcode, Type *Dst,
VectorType *VecTy, unsigned Index);
InstructionCost getCFInstrCost(unsigned Opcode, TTI::TargetCostKind CostKind,
const Instruction *I = nullptr);
InstructionCost getVectorInstrCost(unsigned Opcode, Type *Val,
TTI::TargetCostKind CostKind,
unsigned Index, Value *Op0, Value *Op1);
InstructionCost getVectorInstrCost(const Instruction &I, Type *Val,
TTI::TargetCostKind CostKind,
unsigned Index);
InstructionCost getMinMaxReductionCost(Intrinsic::ID IID, VectorType *Ty,
FastMathFlags FMF,
TTI::TargetCostKind CostKind);
InstructionCost getArithmeticReductionCostSVE(unsigned Opcode,
VectorType *ValTy,
TTI::TargetCostKind CostKind);
InstructionCost getSpliceCost(VectorType *Tp, int Index);
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 = ArrayRef<const Value *>(),
const Instruction *CxtI = nullptr);
InstructionCost getAddressComputationCost(Type *Ty, ScalarEvolution *SE,
const SCEV *Ptr);
InstructionCost getCmpSelInstrCost(unsigned Opcode, Type *ValTy, Type *CondTy,
CmpInst::Predicate VecPred,
TTI::TargetCostKind CostKind,
const Instruction *I = nullptr);
TTI::MemCmpExpansionOptions enableMemCmpExpansion(bool OptSize,
bool IsZeroCmp) const;
bool useNeonVector(const Type *Ty) const;
getMemoryOpCost(unsigned Opcode, Type *Src, MaybeAlign Alignment,
unsigned AddressSpace, TTI::TargetCostKind CostKind,
TTI::OperandValueInfo OpInfo = {TTI::OK_AnyValue, TTI::OP_None},
const Instruction *I = nullptr);
InstructionCost getCostOfKeepingLiveOverCall(ArrayRef<Type *> Tys);
void getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
TTI::UnrollingPreferences &UP,
OptimizationRemarkEmitter *ORE);
void getPeelingPreferences(Loop *L, ScalarEvolution &SE,
TTI::PeelingPreferences &PP);
Value *getOrCreateResultFromMemIntrinsic(IntrinsicInst *Inst,
Type *ExpectedType);
bool getTgtMemIntrinsic(IntrinsicInst *Inst, MemIntrinsicInfo &Info);
bool isElementTypeLegalForScalableVector(Type *Ty) const {
if (Ty->isPointerTy())
return true;
if (Ty->isBFloatTy() && ST->hasBF16())
return true;
if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy())
return true;
if (Ty->isIntegerTy(8) || Ty->isIntegerTy(16) ||
Ty->isIntegerTy(32) || Ty->isIntegerTy(64))
return true;
return false;
bool isLegalMaskedLoadStore(Type *DataType, Align Alignment) {
if (!ST->hasSVE())
return false;
// For fixed vectors, avoid scalarization if using SVE for them.
if (isa<FixedVectorType>(DataType) && !ST->useSVEForFixedLengthVectors())
return false; // Fall back to scalarization of masked operations.
return isElementTypeLegalForScalableVector(DataType->getScalarType());
bool isLegalMaskedLoad(Type *DataType, Align Alignment) {
return isLegalMaskedLoadStore(DataType, Alignment);
bool isLegalMaskedStore(Type *DataType, Align Alignment) {
return isLegalMaskedLoadStore(DataType, Alignment);
bool isLegalMaskedGatherScatter(Type *DataType) const {
if (!ST->hasSVE() || !ST->isNeonAvailable())
return false;
// For fixed vectors, scalarize if not using SVE for them.
auto *DataTypeFVTy = dyn_cast<FixedVectorType>(DataType);
if (DataTypeFVTy && (!ST->useSVEForFixedLengthVectors() ||
DataTypeFVTy->getNumElements() < 2))
return false;
return isElementTypeLegalForScalableVector(DataType->getScalarType());
bool isLegalMaskedGather(Type *DataType, Align Alignment) const {
return isLegalMaskedGatherScatter(DataType);
bool isLegalMaskedScatter(Type *DataType, Align Alignment) const {
return isLegalMaskedGatherScatter(DataType);
bool isLegalBroadcastLoad(Type *ElementTy, ElementCount NumElements) const {
// Return true if we can generate a `ld1r` splat load instruction.
if (!ST->hasNEON() || NumElements.isScalable())
return false;
switch (unsigned ElementBits = ElementTy->getScalarSizeInBits()) {
case 8:
case 16:
case 32:
case 64: {
// We accept bit-widths >= 64bits and elements {8,16,32,64} bits.
unsigned VectorBits = NumElements.getFixedValue() * ElementBits;
return VectorBits >= 64;
return false;
bool isLegalNTStoreLoad(Type *DataType, Align Alignment) {
// NOTE: The logic below is mostly geared towards LV, which calls it with
// vectors with 2 elements. We might want to improve that, if other
// users show up.
// Nontemporal vector loads/stores can be directly lowered to LDNP/STNP, if
// the vector can be halved so that each half fits into a register. That's
// the case if the element type fits into a register and the number of
// elements is a power of 2 > 1.
if (auto *DataTypeTy = dyn_cast<FixedVectorType>(DataType)) {
unsigned NumElements = DataTypeTy->getNumElements();
unsigned EltSize = DataTypeTy->getElementType()->getScalarSizeInBits();
return NumElements > 1 && isPowerOf2_64(NumElements) && EltSize >= 8 &&
EltSize <= 128 && isPowerOf2_64(EltSize);
return BaseT::isLegalNTStore(DataType, Alignment);
bool isLegalNTStore(Type *DataType, Align Alignment) {
return isLegalNTStoreLoad(DataType, Alignment);
bool isLegalNTLoad(Type *DataType, Align Alignment) {
// Only supports little-endian targets.
if (ST->isLittleEndian())
return isLegalNTStoreLoad(DataType, Alignment);
return BaseT::isLegalNTLoad(DataType, Alignment);
bool enableOrderedReductions() const { return true; }
InstructionCost getInterleavedMemoryOpCost(
unsigned Opcode, Type *VecTy, unsigned Factor, ArrayRef<unsigned> Indices,
Align Alignment, unsigned AddressSpace, TTI::TargetCostKind CostKind,
bool UseMaskForCond = false, bool UseMaskForGaps = false);
shouldConsiderAddressTypePromotion(const Instruction &I,
bool &AllowPromotionWithoutCommonHeader);
bool shouldExpandReduction(const IntrinsicInst *II) const { return false; }
unsigned getGISelRematGlobalCost() const {
return 2;
unsigned getMinTripCountTailFoldingThreshold() const {
return ST->hasSVE() ? 5 : 0;
TailFoldingStyle getPreferredTailFoldingStyle(bool IVUpdateMayOverflow) const {
if (ST->hasSVE())
return IVUpdateMayOverflow
? TailFoldingStyle::DataAndControlFlowWithoutRuntimeCheck
: TailFoldingStyle::DataAndControlFlow;
return TailFoldingStyle::DataWithoutLaneMask;
bool preferPredicateOverEpilogue(TailFoldingInfo *TFI);
bool supportsScalableVectors() const { return ST->hasSVE(); }
bool enableScalableVectorization() const { return ST->hasSVE(); }
bool isLegalToVectorizeReduction(const RecurrenceDescriptor &RdxDesc,
ElementCount VF) const;
bool preferPredicatedReductionSelect(unsigned Opcode, Type *Ty,
TTI::ReductionFlags Flags) const {
return ST->hasSVE();
InstructionCost getArithmeticReductionCost(unsigned Opcode, VectorType *Ty,
std::optional<FastMathFlags> FMF,
TTI::TargetCostKind CostKind);
InstructionCost getShuffleCost(TTI::ShuffleKind Kind, VectorType *Tp,
ArrayRef<int> Mask,
TTI::TargetCostKind CostKind, int Index,
VectorType *SubTp,
ArrayRef<const Value *> Args = std::nullopt);
InstructionCost getScalarizationOverhead(VectorType *Ty,
const APInt &DemandedElts,
bool Insert, bool Extract,
TTI::TargetCostKind CostKind);
/// Return the cost of the scaling factor used in the addressing
/// mode represented by AM for this target, for a load/store
/// of the specified type.
/// If the AM is supported, the return value must be >= 0.
/// If the AM is not supported, it returns a negative value.
InstructionCost getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
int64_t BaseOffset, bool HasBaseReg,
int64_t Scale, unsigned AddrSpace) const;
/// @}
bool enableSelectOptimize() { return ST->enableSelectOptimize(); }
unsigned getStoreMinimumVF(unsigned VF, Type *ScalarMemTy,
Type *ScalarValTy) const {
// We can vectorize store v4i8.
if (ScalarMemTy->isIntegerTy(8) && isPowerOf2_32(VF) && VF >= 4)
return 4;
return BaseT::getStoreMinimumVF(VF, ScalarMemTy, ScalarValTy);
} // end namespace llvm