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swiftshader / SwiftShader / refs/heads/llvm10-clean / . / third_party / llvm-10.0 / llvm / lib / Target / ARM / ARMTargetTransformInfo.cpp
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//===- ARMTargetTransformInfo.cpp - ARM specific TTI ----------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "ARMTargetTransformInfo.h"
#include "ARMSubtarget.h"
#include "MCTargetDesc/ARMAddressingModes.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/CodeGen/CostTable.h"
#include "llvm/CodeGen/ISDOpcodes.h"
#include "llvm/CodeGen/ValueTypes.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/IR/Type.h"
#include "llvm/MC/SubtargetFeature.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/MachineValueType.h"
#include "llvm/Target/TargetMachine.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <utility>
using namespace llvm;
#define DEBUG_TYPE "armtti"
static cl::opt<bool> EnableMaskedLoadStores(
"enable-arm-maskedldst", cl::Hidden, cl::init(true),
cl::desc("Enable the generation of masked loads and stores"));
static cl::opt<bool> DisableLowOverheadLoops(
"disable-arm-loloops", cl::Hidden, cl::init(false),
cl::desc("Disable the generation of low-overhead loops"));
extern cl::opt<bool> DisableTailPredication;
extern cl::opt<bool> EnableMaskedGatherScatters;
bool ARMTTIImpl::areInlineCompatible(const Function *Caller,
const Function *Callee) const {
const TargetMachine &TM = getTLI()->getTargetMachine();
const FeatureBitset &CallerBits =
TM.getSubtargetImpl(*Caller)->getFeatureBits();
const FeatureBitset &CalleeBits =
TM.getSubtargetImpl(*Callee)->getFeatureBits();
// To inline a callee, all features not in the whitelist must match exactly.
bool MatchExact = (CallerBits & ~InlineFeatureWhitelist) ==
(CalleeBits & ~InlineFeatureWhitelist);
// For features in the whitelist, the callee's features must be a subset of
// the callers'.
bool MatchSubset = ((CallerBits & CalleeBits) & InlineFeatureWhitelist) ==
(CalleeBits & InlineFeatureWhitelist);
return MatchExact && MatchSubset;
}
int ARMTTIImpl::getIntImmCost(const APInt &Imm, Type *Ty) {
assert(Ty->isIntegerTy());
unsigned Bits = Ty->getPrimitiveSizeInBits();
if (Bits == 0 || Imm.getActiveBits() >= 64)
return 4;
int64_t SImmVal = Imm.getSExtValue();
uint64_t ZImmVal = Imm.getZExtValue();
if (!ST->isThumb()) {
if ((SImmVal >= 0 && SImmVal < 65536) ||
(ARM_AM::getSOImmVal(ZImmVal) != -1) ||
(ARM_AM::getSOImmVal(~ZImmVal) != -1))
return 1;
return ST->hasV6T2Ops() ? 2 : 3;
}
if (ST->isThumb2()) {
if ((SImmVal >= 0 && SImmVal < 65536) ||
(ARM_AM::getT2SOImmVal(ZImmVal) != -1) ||
(ARM_AM::getT2SOImmVal(~ZImmVal) != -1))
return 1;
return ST->hasV6T2Ops() ? 2 : 3;
}
// Thumb1, any i8 imm cost 1.
if (Bits == 8 || (SImmVal >= 0 && SImmVal < 256))
return 1;
if ((~SImmVal < 256) || ARM_AM::isThumbImmShiftedVal(ZImmVal))
return 2;
// Load from constantpool.
return 3;
}
// Constants smaller than 256 fit in the immediate field of
// Thumb1 instructions so we return a zero cost and 1 otherwise.
int ARMTTIImpl::getIntImmCodeSizeCost(unsigned Opcode, unsigned Idx,
const APInt &Imm, Type *Ty) {
if (Imm.isNonNegative() && Imm.getLimitedValue() < 256)
return 0;
return 1;
}
int ARMTTIImpl::getIntImmCostInst(unsigned Opcode, unsigned Idx, const APInt &Imm,
Type *Ty) {
// Division by a constant can be turned into multiplication, but only if we
// know it's constant. So it's not so much that the immediate is cheap (it's
// not), but that the alternative is worse.
// FIXME: this is probably unneeded with GlobalISel.
if ((Opcode == Instruction::SDiv || Opcode == Instruction::UDiv ||
Opcode == Instruction::SRem || Opcode == Instruction::URem) &&
Idx == 1)
return 0;
if (Opcode == Instruction::And) {
// UXTB/UXTH
if (Imm == 255 || Imm == 65535)
return 0;
// Conversion to BIC is free, and means we can use ~Imm instead.
return std::min(getIntImmCost(Imm, Ty), getIntImmCost(~Imm, Ty));
}
if (Opcode == Instruction::Add)
// Conversion to SUB is free, and means we can use -Imm instead.
return std::min(getIntImmCost(Imm, Ty), getIntImmCost(-Imm, Ty));
if (Opcode == Instruction::ICmp && Imm.isNegative() &&
Ty->getIntegerBitWidth() == 32) {
int64_t NegImm = -Imm.getSExtValue();
if (ST->isThumb2() && NegImm < 1<<12)
// icmp X, #-C -> cmn X, #C
return 0;
if (ST->isThumb() && NegImm < 1<<8)
// icmp X, #-C -> adds X, #C
return 0;
}
// xor a, -1 can always be folded to MVN
if (Opcode == Instruction::Xor && Imm.isAllOnesValue())
return 0;
return getIntImmCost(Imm, Ty);
}
int ARMTTIImpl::getCastInstrCost(unsigned Opcode, Type *Dst, Type *Src,
const Instruction *I) {
int ISD = TLI->InstructionOpcodeToISD(Opcode);
assert(ISD && "Invalid opcode");
// Single to/from double precision conversions.
static const CostTblEntry NEONFltDblTbl[] = {
// Vector fptrunc/fpext conversions.
{ ISD::FP_ROUND, MVT::v2f64, 2 },
{ ISD::FP_EXTEND, MVT::v2f32, 2 },
{ ISD::FP_EXTEND, MVT::v4f32, 4 }
};
if (Src->isVectorTy() && ST->hasNEON() && (ISD == ISD::FP_ROUND ||
ISD == ISD::FP_EXTEND)) {
std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, Src);
if (const auto *Entry = CostTableLookup(NEONFltDblTbl, ISD, LT.second))
return LT.first * Entry->Cost;
}
EVT SrcTy = TLI->getValueType(DL, Src);
EVT DstTy = TLI->getValueType(DL, Dst);
if (!SrcTy.isSimple() || !DstTy.isSimple())
return BaseT::getCastInstrCost(Opcode, Dst, Src);
// The extend of a load is free
if (I && isa<LoadInst>(I->getOperand(0))) {
static const TypeConversionCostTblEntry LoadConversionTbl[] = {
{ISD::SIGN_EXTEND, MVT::i32, MVT::i16, 0},
{ISD::ZERO_EXTEND, MVT::i32, MVT::i16, 0},
{ISD::SIGN_EXTEND, MVT::i32, MVT::i8, 0},
{ISD::ZERO_EXTEND, MVT::i32, MVT::i8, 0},
{ISD::SIGN_EXTEND, MVT::i16, MVT::i8, 0},
{ISD::ZERO_EXTEND, MVT::i16, MVT::i8, 0},
{ISD::SIGN_EXTEND, MVT::i64, MVT::i32, 1},
{ISD::ZERO_EXTEND, MVT::i64, MVT::i32, 1},
{ISD::SIGN_EXTEND, MVT::i64, MVT::i16, 1},
{ISD::ZERO_EXTEND, MVT::i64, MVT::i16, 1},
{ISD::SIGN_EXTEND, MVT::i64, MVT::i8, 1},
{ISD::ZERO_EXTEND, MVT::i64, MVT::i8, 1},
};
if (const auto *Entry = ConvertCostTableLookup(
LoadConversionTbl, ISD, DstTy.getSimpleVT(), SrcTy.getSimpleVT()))
return Entry->Cost;
static const TypeConversionCostTblEntry MVELoadConversionTbl[] = {
{ISD::SIGN_EXTEND, MVT::v4i32, MVT::v4i16, 0},
{ISD::ZERO_EXTEND, MVT::v4i32, MVT::v4i16, 0},
{ISD::SIGN_EXTEND, MVT::v4i32, MVT::v4i8, 0},
{ISD::ZERO_EXTEND, MVT::v4i32, MVT::v4i8, 0},
{ISD::SIGN_EXTEND, MVT::v8i16, MVT::v8i8, 0},
{ISD::ZERO_EXTEND, MVT::v8i16, MVT::v8i8, 0},
};
if (SrcTy.isVector() && ST->hasMVEIntegerOps()) {
if (const auto *Entry =
ConvertCostTableLookup(MVELoadConversionTbl, ISD,
DstTy.getSimpleVT(), SrcTy.getSimpleVT()))
return Entry->Cost;
}
}
// Some arithmetic, load and store operations have specific instructions
// to cast up/down their types automatically at no extra cost.
// TODO: Get these tables to know at least what the related operations are.
static const TypeConversionCostTblEntry NEONVectorConversionTbl[] = {
{ ISD::SIGN_EXTEND, MVT::v4i32, MVT::v4i16, 0 },
{ ISD::ZERO_EXTEND, MVT::v4i32, MVT::v4i16, 0 },
{ ISD::SIGN_EXTEND, MVT::v2i64, MVT::v2i32, 1 },
{ ISD::ZERO_EXTEND, MVT::v2i64, MVT::v2i32, 1 },
{ ISD::TRUNCATE, MVT::v4i32, MVT::v4i64, 0 },
{ ISD::TRUNCATE, MVT::v4i16, MVT::v4i32, 1 },
// The number of vmovl instructions for the extension.
{ ISD::SIGN_EXTEND, MVT::v4i64, MVT::v4i16, 3 },
{ ISD::ZERO_EXTEND, MVT::v4i64, MVT::v4i16, 3 },
{ ISD::SIGN_EXTEND, MVT::v8i32, MVT::v8i8, 3 },
{ ISD::ZERO_EXTEND, MVT::v8i32, MVT::v8i8, 3 },
{ ISD::SIGN_EXTEND, MVT::v8i64, MVT::v8i8, 7 },
{ ISD::ZERO_EXTEND, MVT::v8i64, MVT::v8i8, 7 },
{ ISD::SIGN_EXTEND, MVT::v8i64, MVT::v8i16, 6 },
{ ISD::ZERO_EXTEND, MVT::v8i64, MVT::v8i16, 6 },
{ ISD::SIGN_EXTEND, MVT::v16i32, MVT::v16i8, 6 },
{ ISD::ZERO_EXTEND, MVT::v16i32, MVT::v16i8, 6 },
// Operations that we legalize using splitting.
{ ISD::TRUNCATE, MVT::v16i8, MVT::v16i32, 6 },
{ ISD::TRUNCATE, MVT::v8i8, MVT::v8i32, 3 },
// Vector float <-> i32 conversions.
{ ISD::SINT_TO_FP, MVT::v4f32, MVT::v4i32, 1 },
{ ISD::UINT_TO_FP, MVT::v4f32, MVT::v4i32, 1 },
{ ISD::SINT_TO_FP, MVT::v2f32, MVT::v2i8, 3 },
{ ISD::UINT_TO_FP, MVT::v2f32, MVT::v2i8, 3 },
{ ISD::SINT_TO_FP, MVT::v2f32, MVT::v2i16, 2 },
{ ISD::UINT_TO_FP, MVT::v2f32, MVT::v2i16, 2 },
{ ISD::SINT_TO_FP, MVT::v2f32, MVT::v2i32, 1 },
{ ISD::UINT_TO_FP, MVT::v2f32, MVT::v2i32, 1 },
{ ISD::SINT_TO_FP, MVT::v4f32, MVT::v4i1, 3 },
{ ISD::UINT_TO_FP, MVT::v4f32, MVT::v4i1, 3 },
{ ISD::SINT_TO_FP, MVT::v4f32, MVT::v4i8, 3 },
{ ISD::UINT_TO_FP, MVT::v4f32, MVT::v4i8, 3 },
{ ISD::SINT_TO_FP, MVT::v4f32, MVT::v4i16, 2 },
{ ISD::UINT_TO_FP, MVT::v4f32, MVT::v4i16, 2 },
{ ISD::SINT_TO_FP, MVT::v8f32, MVT::v8i16, 4 },
{ ISD::UINT_TO_FP, MVT::v8f32, MVT::v8i16, 4 },
{ ISD::SINT_TO_FP, MVT::v8f32, MVT::v8i32, 2 },
{ ISD::UINT_TO_FP, MVT::v8f32, MVT::v8i32, 2 },
{ ISD::SINT_TO_FP, MVT::v16f32, MVT::v16i16, 8 },
{ ISD::UINT_TO_FP, MVT::v16f32, MVT::v16i16, 8 },
{ ISD::SINT_TO_FP, MVT::v16f32, MVT::v16i32, 4 },
{ ISD::UINT_TO_FP, MVT::v16f32, MVT::v16i32, 4 },
{ ISD::FP_TO_SINT, MVT::v4i32, MVT::v4f32, 1 },
{ ISD::FP_TO_UINT, MVT::v4i32, MVT::v4f32, 1 },
{ ISD::FP_TO_SINT, MVT::v4i8, MVT::v4f32, 3 },
{ ISD::FP_TO_UINT, MVT::v4i8, MVT::v4f32, 3 },
{ ISD::FP_TO_SINT, MVT::v4i16, MVT::v4f32, 2 },
{ ISD::FP_TO_UINT, MVT::v4i16, MVT::v4f32, 2 },
// Vector double <-> i32 conversions.
{ ISD::SINT_TO_FP, MVT::v2f64, MVT::v2i32, 2 },
{ ISD::UINT_TO_FP, MVT::v2f64, MVT::v2i32, 2 },
{ ISD::SINT_TO_FP, MVT::v2f64, MVT::v2i8, 4 },
{ ISD::UINT_TO_FP, MVT::v2f64, MVT::v2i8, 4 },
{ ISD::SINT_TO_FP, MVT::v2f64, MVT::v2i16, 3 },
{ ISD::UINT_TO_FP, MVT::v2f64, MVT::v2i16, 3 },
{ ISD::SINT_TO_FP, MVT::v2f64, MVT::v2i32, 2 },
{ ISD::UINT_TO_FP, MVT::v2f64, MVT::v2i32, 2 },
{ ISD::FP_TO_SINT, MVT::v2i32, MVT::v2f64, 2 },
{ ISD::FP_TO_UINT, MVT::v2i32, MVT::v2f64, 2 },
{ ISD::FP_TO_SINT, MVT::v8i16, MVT::v8f32, 4 },
{ ISD::FP_TO_UINT, MVT::v8i16, MVT::v8f32, 4 },
{ ISD::FP_TO_SINT, MVT::v16i16, MVT::v16f32, 8 },
{ ISD::FP_TO_UINT, MVT::v16i16, MVT::v16f32, 8 }
};
if (SrcTy.isVector() && ST->hasNEON()) {
if (const auto *Entry = ConvertCostTableLookup(NEONVectorConversionTbl, ISD,
DstTy.getSimpleVT(),
SrcTy.getSimpleVT()))
return Entry->Cost;
}
// Scalar float to integer conversions.
static const TypeConversionCostTblEntry NEONFloatConversionTbl[] = {
{ ISD::FP_TO_SINT, MVT::i1, MVT::f32, 2 },
{ ISD::FP_TO_UINT, MVT::i1, MVT::f32, 2 },
{ ISD::FP_TO_SINT, MVT::i1, MVT::f64, 2 },
{ ISD::FP_TO_UINT, MVT::i1, MVT::f64, 2 },
{ ISD::FP_TO_SINT, MVT::i8, MVT::f32, 2 },
{ ISD::FP_TO_UINT, MVT::i8, MVT::f32, 2 },
{ ISD::FP_TO_SINT, MVT::i8, MVT::f64, 2 },
{ ISD::FP_TO_UINT, MVT::i8, MVT::f64, 2 },
{ ISD::FP_TO_SINT, MVT::i16, MVT::f32, 2 },
{ ISD::FP_TO_UINT, MVT::i16, MVT::f32, 2 },
{ ISD::FP_TO_SINT, MVT::i16, MVT::f64, 2 },
{ ISD::FP_TO_UINT, MVT::i16, MVT::f64, 2 },
{ ISD::FP_TO_SINT, MVT::i32, MVT::f32, 2 },
{ ISD::FP_TO_UINT, MVT::i32, MVT::f32, 2 },
{ ISD::FP_TO_SINT, MVT::i32, MVT::f64, 2 },
{ ISD::FP_TO_UINT, MVT::i32, MVT::f64, 2 },
{ ISD::FP_TO_SINT, MVT::i64, MVT::f32, 10 },
{ ISD::FP_TO_UINT, MVT::i64, MVT::f32, 10 },
{ ISD::FP_TO_SINT, MVT::i64, MVT::f64, 10 },
{ ISD::FP_TO_UINT, MVT::i64, MVT::f64, 10 }
};
if (SrcTy.isFloatingPoint() && ST->hasNEON()) {
if (const auto *Entry = ConvertCostTableLookup(NEONFloatConversionTbl, ISD,
DstTy.getSimpleVT(),
SrcTy.getSimpleVT()))
return Entry->Cost;
}
// Scalar integer to float conversions.
static const TypeConversionCostTblEntry NEONIntegerConversionTbl[] = {
{ ISD::SINT_TO_FP, MVT::f32, MVT::i1, 2 },
{ ISD::UINT_TO_FP, MVT::f32, MVT::i1, 2 },
{ ISD::SINT_TO_FP, MVT::f64, MVT::i1, 2 },
{ ISD::UINT_TO_FP, MVT::f64, MVT::i1, 2 },
{ ISD::SINT_TO_FP, MVT::f32, MVT::i8, 2 },
{ ISD::UINT_TO_FP, MVT::f32, MVT::i8, 2 },
{ ISD::SINT_TO_FP, MVT::f64, MVT::i8, 2 },
{ ISD::UINT_TO_FP, MVT::f64, MVT::i8, 2 },
{ ISD::SINT_TO_FP, MVT::f32, MVT::i16, 2 },
{ ISD::UINT_TO_FP, MVT::f32, MVT::i16, 2 },
{ ISD::SINT_TO_FP, MVT::f64, MVT::i16, 2 },
{ ISD::UINT_TO_FP, MVT::f64, MVT::i16, 2 },
{ ISD::SINT_TO_FP, MVT::f32, MVT::i32, 2 },
{ ISD::UINT_TO_FP, MVT::f32, MVT::i32, 2 },
{ ISD::SINT_TO_FP, MVT::f64, MVT::i32, 2 },
{ ISD::UINT_TO_FP, MVT::f64, MVT::i32, 2 },
{ ISD::SINT_TO_FP, MVT::f32, MVT::i64, 10 },
{ ISD::UINT_TO_FP, MVT::f32, MVT::i64, 10 },
{ ISD::SINT_TO_FP, MVT::f64, MVT::i64, 10 },
{ ISD::UINT_TO_FP, MVT::f64, MVT::i64, 10 }
};
if (SrcTy.isInteger() && ST->hasNEON()) {
if (const auto *Entry = ConvertCostTableLookup(NEONIntegerConversionTbl,
ISD, DstTy.getSimpleVT(),
SrcTy.getSimpleVT()))
return Entry->Cost;
}
// MVE extend costs, taken from codegen tests. i8->i16 or i16->i32 is one
// instruction, i8->i32 is two. i64 zexts are an VAND with a constant, sext
// are linearised so take more.
static const TypeConversionCostTblEntry MVEVectorConversionTbl[] = {
{ ISD::SIGN_EXTEND, MVT::v8i16, MVT::v8i8, 1 },
{ ISD::ZERO_EXTEND, MVT::v8i16, MVT::v8i8, 1 },
{ ISD::SIGN_EXTEND, MVT::v4i32, MVT::v4i8, 2 },
{ ISD::ZERO_EXTEND, MVT::v4i32, MVT::v4i8, 2 },
{ ISD::SIGN_EXTEND, MVT::v2i64, MVT::v2i8, 10 },
{ ISD::ZERO_EXTEND, MVT::v2i64, MVT::v2i8, 2 },
{ ISD::SIGN_EXTEND, MVT::v4i32, MVT::v4i16, 1 },
{ ISD::ZERO_EXTEND, MVT::v4i32, MVT::v4i16, 1 },
{ ISD::SIGN_EXTEND, MVT::v2i64, MVT::v2i16, 10 },
{ ISD::ZERO_EXTEND, MVT::v2i64, MVT::v2i16, 2 },
{ ISD::SIGN_EXTEND, MVT::v2i64, MVT::v2i32, 8 },
{ ISD::ZERO_EXTEND, MVT::v2i64, MVT::v2i32, 2 },
};
if (SrcTy.isVector() && ST->hasMVEIntegerOps()) {
if (const auto *Entry = ConvertCostTableLookup(MVEVectorConversionTbl,
ISD, DstTy.getSimpleVT(),
SrcTy.getSimpleVT()))
return Entry->Cost * ST->getMVEVectorCostFactor();
}
// Scalar integer conversion costs.
static const TypeConversionCostTblEntry ARMIntegerConversionTbl[] = {
// i16 -> i64 requires two dependent operations.
{ ISD::SIGN_EXTEND, MVT::i64, MVT::i16, 2 },
// Truncates on i64 are assumed to be free.
{ ISD::TRUNCATE, MVT::i32, MVT::i64, 0 },
{ ISD::TRUNCATE, MVT::i16, MVT::i64, 0 },
{ ISD::TRUNCATE, MVT::i8, MVT::i64, 0 },
{ ISD::TRUNCATE, MVT::i1, MVT::i64, 0 }
};
if (SrcTy.isInteger()) {
if (const auto *Entry = ConvertCostTableLookup(ARMIntegerConversionTbl, ISD,
DstTy.getSimpleVT(),
SrcTy.getSimpleVT()))
return Entry->Cost;
}
int BaseCost = ST->hasMVEIntegerOps() && Src->isVectorTy()
? ST->getMVEVectorCostFactor()
: 1;
return BaseCost * BaseT::getCastInstrCost(Opcode, Dst, Src);
}
int ARMTTIImpl::getVectorInstrCost(unsigned Opcode, Type *ValTy,
unsigned Index) {
// Penalize inserting into an D-subregister. We end up with a three times
// lower estimated throughput on swift.
if (ST->hasSlowLoadDSubregister() && Opcode == Instruction::InsertElement &&
ValTy->isVectorTy() && ValTy->getScalarSizeInBits() <= 32)
return 3;
if (ST->hasNEON() && (Opcode == Instruction::InsertElement ||
Opcode == Instruction::ExtractElement)) {
// Cross-class copies are expensive on many microarchitectures,
// so assume they are expensive by default.
if (ValTy->getVectorElementType()->isIntegerTy())
return 3;
// Even if it's not a cross class copy, this likely leads to mixing
// of NEON and VFP code and should be therefore penalized.
if (ValTy->isVectorTy() &&
ValTy->getScalarSizeInBits() <= 32)
return std::max(BaseT::getVectorInstrCost(Opcode, ValTy, Index), 2U);
}
if (ST->hasMVEIntegerOps() && (Opcode == Instruction::InsertElement ||
Opcode == Instruction::ExtractElement)) {
// We say MVE moves costs at least the MVEVectorCostFactor, even though
// they are scalar instructions. This helps prevent mixing scalar and
// vector, to prevent vectorising where we end up just scalarising the
// result anyway.
return std::max(BaseT::getVectorInstrCost(Opcode, ValTy, Index),
ST->getMVEVectorCostFactor()) *
ValTy->getVectorNumElements() / 2;
}
return BaseT::getVectorInstrCost(Opcode, ValTy, Index);
}
int ARMTTIImpl::getCmpSelInstrCost(unsigned Opcode, Type *ValTy, Type *CondTy,
const Instruction *I) {
int ISD = TLI->InstructionOpcodeToISD(Opcode);
// On NEON a vector select gets lowered to vbsl.
if (ST->hasNEON() && ValTy->isVectorTy() && ISD == ISD::SELECT) {
// Lowering of some vector selects is currently far from perfect.
static const TypeConversionCostTblEntry NEONVectorSelectTbl[] = {
{ ISD::SELECT, MVT::v4i1, MVT::v4i64, 4*4 + 1*2 + 1 },
{ ISD::SELECT, MVT::v8i1, MVT::v8i64, 50 },
{ ISD::SELECT, MVT::v16i1, MVT::v16i64, 100 }
};
EVT SelCondTy = TLI->getValueType(DL, CondTy);
EVT SelValTy = TLI->getValueType(DL, ValTy);
if (SelCondTy.isSimple() && SelValTy.isSimple()) {
if (const auto *Entry = ConvertCostTableLookup(NEONVectorSelectTbl, ISD,
SelCondTy.getSimpleVT(),
SelValTy.getSimpleVT()))
return Entry->Cost;
}
std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, ValTy);
return LT.first;
}
int BaseCost = ST->hasMVEIntegerOps() && ValTy->isVectorTy()
? ST->getMVEVectorCostFactor()
: 1;
return BaseCost * BaseT::getCmpSelInstrCost(Opcode, ValTy, CondTy, I);
}
int ARMTTIImpl::getAddressComputationCost(Type *Ty, ScalarEvolution *SE,
const SCEV *Ptr) {
// Address computations in vectorized code with non-consecutive addresses will
// likely result in more instructions compared to scalar code where the
// computation can more often be merged into the index mode. The resulting
// extra micro-ops can significantly decrease throughput.
unsigned NumVectorInstToHideOverhead = 10;
int MaxMergeDistance = 64;
if (ST->hasNEON()) {
if (Ty->isVectorTy() && SE &&
!BaseT::isConstantStridedAccessLessThan(SE, Ptr, MaxMergeDistance + 1))
return NumVectorInstToHideOverhead;
// In many cases the address computation is not merged into the instruction
// addressing mode.
return 1;
}
return BaseT::getAddressComputationCost(Ty, SE, Ptr);
}
bool ARMTTIImpl::isLegalMaskedLoad(Type *DataTy, MaybeAlign Alignment) {
if (!EnableMaskedLoadStores || !ST->hasMVEIntegerOps())
return false;
if (auto *VecTy = dyn_cast<VectorType>(DataTy)) {
// Don't support v2i1 yet.
if (VecTy->getNumElements() == 2)
return false;
// We don't support extending fp types.
unsigned VecWidth = DataTy->getPrimitiveSizeInBits();
if (VecWidth != 128 && VecTy->getElementType()->isFloatingPointTy())
return false;
}
unsigned EltWidth = DataTy->getScalarSizeInBits();
return (EltWidth == 32 && (!Alignment || Alignment >= 4)) ||
(EltWidth == 16 && (!Alignment || Alignment >= 2)) ||
(EltWidth == 8);
}
bool ARMTTIImpl::isLegalMaskedGather(Type *Ty, MaybeAlign Alignment) {
if (!EnableMaskedGatherScatters || !ST->hasMVEIntegerOps())
return false;
// This method is called in 2 places:
// - from the vectorizer with a scalar type, in which case we need to get
// this as good as we can with the limited info we have (and rely on the cost
// model for the rest).
// - from the masked intrinsic lowering pass with the actual vector type.
// For MVE, we have a custom lowering pass that will already have custom
// legalised any gathers that we can to MVE intrinsics, and want to expand all
// the rest. The pass runs before the masked intrinsic lowering pass, so if we
// are here, we know we want to expand.
if (isa<VectorType>(Ty))
return false;
unsigned EltWidth = Ty->getScalarSizeInBits();
return ((EltWidth == 32 && (!Alignment || Alignment >= 4)) ||
(EltWidth == 16 && (!Alignment || Alignment >= 2)) || EltWidth == 8);
}
int ARMTTIImpl::getMemcpyCost(const Instruction *I) {
const MemCpyInst *MI = dyn_cast<MemCpyInst>(I);
assert(MI && "MemcpyInst expected");
ConstantInt *C = dyn_cast<ConstantInt>(MI->getLength());
// To model the cost of a library call, we assume 1 for the call, and
// 3 for the argument setup.
const unsigned LibCallCost = 4;
// If 'size' is not a constant, a library call will be generated.
if (!C)
return LibCallCost;
const unsigned Size = C->getValue().getZExtValue();
const unsigned DstAlign = MI->getDestAlignment();
const unsigned SrcAlign = MI->getSourceAlignment();
const Function *F = I->getParent()->getParent();
const unsigned Limit = TLI->getMaxStoresPerMemmove(F->hasMinSize());
std::vector<EVT> MemOps;
// MemOps will be poplulated with a list of data types that needs to be
// loaded and stored. That's why we multiply the number of elements by 2 to
// get the cost for this memcpy.
if (getTLI()->findOptimalMemOpLowering(
MemOps, Limit, Size, DstAlign, SrcAlign, false /*IsMemset*/,
false /*ZeroMemset*/, false /*MemcpyStrSrc*/, false /*AllowOverlap*/,
MI->getDestAddressSpace(), MI->getSourceAddressSpace(),
F->getAttributes()))
return MemOps.size() * 2;
// If we can't find an optimal memop lowering, return the default cost
return LibCallCost;
}
int ARMTTIImpl::getShuffleCost(TTI::ShuffleKind Kind, Type *Tp, int Index,
Type *SubTp) {
if (ST->hasNEON()) {
if (Kind == TTI::SK_Broadcast) {
static const CostTblEntry NEONDupTbl[] = {
// VDUP handles these cases.
{ISD::VECTOR_SHUFFLE, MVT::v2i32, 1},
{ISD::VECTOR_SHUFFLE, MVT::v2f32, 1},
{ISD::VECTOR_SHUFFLE, MVT::v2i64, 1},
{ISD::VECTOR_SHUFFLE, MVT::v2f64, 1},
{ISD::VECTOR_SHUFFLE, MVT::v4i16, 1},
{ISD::VECTOR_SHUFFLE, MVT::v8i8, 1},
{ISD::VECTOR_SHUFFLE, MVT::v4i32, 1},
{ISD::VECTOR_SHUFFLE, MVT::v4f32, 1},
{ISD::VECTOR_SHUFFLE, MVT::v8i16, 1},
{ISD::VECTOR_SHUFFLE, MVT::v16i8, 1}};
std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, Tp);
if (const auto *Entry =
CostTableLookup(NEONDupTbl, ISD::VECTOR_SHUFFLE, LT.second))
return LT.first * Entry->Cost;
}
if (Kind == TTI::SK_Reverse) {
static const CostTblEntry NEONShuffleTbl[] = {
// Reverse shuffle cost one instruction if we are shuffling within a
// double word (vrev) or two if we shuffle a quad word (vrev, vext).
{ISD::VECTOR_SHUFFLE, MVT::v2i32, 1},
{ISD::VECTOR_SHUFFLE, MVT::v2f32, 1},
{ISD::VECTOR_SHUFFLE, MVT::v2i64, 1},
{ISD::VECTOR_SHUFFLE, MVT::v2f64, 1},
{ISD::VECTOR_SHUFFLE, MVT::v4i16, 1},
{ISD::VECTOR_SHUFFLE, MVT::v8i8, 1},
{ISD::VECTOR_SHUFFLE, MVT::v4i32, 2},
{ISD::VECTOR_SHUFFLE, MVT::v4f32, 2},
{ISD::VECTOR_SHUFFLE, MVT::v8i16, 2},
{ISD::VECTOR_SHUFFLE, MVT::v16i8, 2}};
std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, Tp);
if (const auto *Entry =
CostTableLookup(NEONShuffleTbl, ISD::VECTOR_SHUFFLE, LT.second))
return LT.first * Entry->Cost;
}
if (Kind == TTI::SK_Select) {
static const CostTblEntry NEONSelShuffleTbl[] = {
// Select shuffle cost table for ARM. Cost is the number of
// instructions
// required to create the shuffled vector.
{ISD::VECTOR_SHUFFLE, MVT::v2f32, 1},
{ISD::VECTOR_SHUFFLE, MVT::v2i64, 1},
{ISD::VECTOR_SHUFFLE, MVT::v2f64, 1},
{ISD::VECTOR_SHUFFLE, MVT::v2i32, 1},
{ISD::VECTOR_SHUFFLE, MVT::v4i32, 2},
{ISD::VECTOR_SHUFFLE, MVT::v4f32, 2},
{ISD::VECTOR_SHUFFLE, MVT::v4i16, 2},
{ISD::VECTOR_SHUFFLE, MVT::v8i16, 16},
{ISD::VECTOR_SHUFFLE, MVT::v16i8, 32}};
std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, Tp);
if (const auto *Entry = CostTableLookup(NEONSelShuffleTbl,
ISD::VECTOR_SHUFFLE, LT.second))
return LT.first * Entry->Cost;
}
}
if (ST->hasMVEIntegerOps()) {
if (Kind == TTI::SK_Broadcast) {
static const CostTblEntry MVEDupTbl[] = {
// VDUP handles these cases.
{ISD::VECTOR_SHUFFLE, MVT::v4i32, 1},
{ISD::VECTOR_SHUFFLE, MVT::v8i16, 1},
{ISD::VECTOR_SHUFFLE, MVT::v16i8, 1},
{ISD::VECTOR_SHUFFLE, MVT::v4f32, 1},
{ISD::VECTOR_SHUFFLE, MVT::v8f16, 1}};
std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, Tp);
if (const auto *Entry = CostTableLookup(MVEDupTbl, ISD::VECTOR_SHUFFLE,
LT.second))
return LT.first * Entry->Cost * ST->getMVEVectorCostFactor();
}
}
int BaseCost = ST->hasMVEIntegerOps() && Tp->isVectorTy()
? ST->getMVEVectorCostFactor()
: 1;
return BaseCost * BaseT::getShuffleCost(Kind, Tp, Index, SubTp);
}
int ARMTTIImpl::getArithmeticInstrCost(unsigned Opcode, Type *Ty,
TTI::OperandValueKind Op1Info,
TTI::OperandValueKind Op2Info,
TTI::OperandValueProperties Opd1PropInfo,
TTI::OperandValueProperties Opd2PropInfo,
ArrayRef<const Value *> Args,
const Instruction *CxtI) {
int ISDOpcode = TLI->InstructionOpcodeToISD(Opcode);
std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, Ty);
if (ST->hasNEON()) {
const unsigned FunctionCallDivCost = 20;
const unsigned ReciprocalDivCost = 10;
static const CostTblEntry CostTbl[] = {
// Division.
// These costs are somewhat random. Choose a cost of 20 to indicate that
// vectorizing devision (added function call) is going to be very expensive.
// Double registers types.
{ ISD::SDIV, MVT::v1i64, 1 * FunctionCallDivCost},
{ ISD::UDIV, MVT::v1i64, 1 * FunctionCallDivCost},
{ ISD::SREM, MVT::v1i64, 1 * FunctionCallDivCost},
{ ISD::UREM, MVT::v1i64, 1 * FunctionCallDivCost},
{ ISD::SDIV, MVT::v2i32, 2 * FunctionCallDivCost},
{ ISD::UDIV, MVT::v2i32, 2 * FunctionCallDivCost},
{ ISD::SREM, MVT::v2i32, 2 * FunctionCallDivCost},
{ ISD::UREM, MVT::v2i32, 2 * FunctionCallDivCost},
{ ISD::SDIV, MVT::v4i16, ReciprocalDivCost},
{ ISD::UDIV, MVT::v4i16, ReciprocalDivCost},
{ ISD::SREM, MVT::v4i16, 4 * FunctionCallDivCost},
{ ISD::UREM, MVT::v4i16, 4 * FunctionCallDivCost},
{ ISD::SDIV, MVT::v8i8, ReciprocalDivCost},
{ ISD::UDIV, MVT::v8i8, ReciprocalDivCost},
{ ISD::SREM, MVT::v8i8, 8 * FunctionCallDivCost},
{ ISD::UREM, MVT::v8i8, 8 * FunctionCallDivCost},
// Quad register types.
{ ISD::SDIV, MVT::v2i64, 2 * FunctionCallDivCost},
{ ISD::UDIV, MVT::v2i64, 2 * FunctionCallDivCost},
{ ISD::SREM, MVT::v2i64, 2 * FunctionCallDivCost},
{ ISD::UREM, MVT::v2i64, 2 * FunctionCallDivCost},
{ ISD::SDIV, MVT::v4i32, 4 * FunctionCallDivCost},
{ ISD::UDIV, MVT::v4i32, 4 * FunctionCallDivCost},
{ ISD::SREM, MVT::v4i32, 4 * FunctionCallDivCost},
{ ISD::UREM, MVT::v4i32, 4 * FunctionCallDivCost},
{ ISD::SDIV, MVT::v8i16, 8 * FunctionCallDivCost},
{ ISD::UDIV, MVT::v8i16, 8 * FunctionCallDivCost},
{ ISD::SREM, MVT::v8i16, 8 * FunctionCallDivCost},
{ ISD::UREM, MVT::v8i16, 8 * FunctionCallDivCost},
{ ISD::SDIV, MVT::v16i8, 16 * FunctionCallDivCost},
{ ISD::UDIV, MVT::v16i8, 16 * FunctionCallDivCost},
{ ISD::SREM, MVT::v16i8, 16 * FunctionCallDivCost},
{ ISD::UREM, MVT::v16i8, 16 * FunctionCallDivCost},
// Multiplication.
};
if (const auto *Entry = CostTableLookup(CostTbl, ISDOpcode, LT.second))
return LT.first * Entry->Cost;
int Cost = BaseT::getArithmeticInstrCost(Opcode, Ty, Op1Info, Op2Info,
Opd1PropInfo, Opd2PropInfo);
// This is somewhat of a hack. The problem that we are facing is that SROA
// creates a sequence of shift, and, or instructions to construct values.
// These sequences are recognized by the ISel and have zero-cost. Not so for
// the vectorized code. Because we have support for v2i64 but not i64 those
// sequences look particularly beneficial to vectorize.
// To work around this we increase the cost of v2i64 operations to make them
// seem less beneficial.
if (LT.second == MVT::v2i64 &&
Op2Info == TargetTransformInfo::OK_UniformConstantValue)
Cost += 4;
return Cost;
}
// If this operation is a shift on arm/thumb2, it might well be folded into
// the following instruction, hence having a cost of 0.
auto LooksLikeAFreeShift = [&]() {
if (ST->isThumb1Only() || Ty->isVectorTy())
return false;
if (!CxtI || !CxtI->hasOneUse() || !CxtI->isShift())
return false;
if (Op2Info != TargetTransformInfo::OK_UniformConstantValue)
return false;
// Folded into a ADC/ADD/AND/BIC/CMP/EOR/MVN/ORR/ORN/RSB/SBC/SUB
switch (cast<Instruction>(CxtI->user_back())->getOpcode()) {
case Instruction::Add:
case Instruction::Sub:
case Instruction::And:
case Instruction::Xor:
case Instruction::Or:
case Instruction::ICmp:
return true;
default:
return false;
}
};
if (LooksLikeAFreeShift())
return 0;
int BaseCost = ST->hasMVEIntegerOps() && Ty->isVectorTy()
? ST->getMVEVectorCostFactor()
: 1;
// The rest of this mostly follows what is done in BaseT::getArithmeticInstrCost,
// without treating floats as more expensive that scalars or increasing the
// costs for custom operations. The results is also multiplied by the
// MVEVectorCostFactor where appropriate.
if (TLI->isOperationLegalOrCustomOrPromote(ISDOpcode, LT.second))
return LT.first * BaseCost;
// Else this is expand, assume that we need to scalarize this op.
if (Ty->isVectorTy()) {
unsigned Num = Ty->getVectorNumElements();
unsigned Cost = getArithmeticInstrCost(Opcode, Ty->getScalarType());
// Return the cost of multiple scalar invocation plus the cost of
// inserting and extracting the values.
return BaseT::getScalarizationOverhead(Ty, Args) + Num * Cost;
}
return BaseCost;
}
int ARMTTIImpl::getMemoryOpCost(unsigned Opcode, Type *Src,
MaybeAlign Alignment, unsigned AddressSpace,
const Instruction *I) {
std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, Src);
if (ST->hasNEON() && Src->isVectorTy() &&
(Alignment && *Alignment != Align(16)) &&
Src->getVectorElementType()->isDoubleTy()) {
// Unaligned loads/stores are extremely inefficient.
// We need 4 uops for vst.1/vld.1 vs 1uop for vldr/vstr.
return LT.first * 4;
}
int BaseCost = ST->hasMVEIntegerOps() && Src->isVectorTy()
? ST->getMVEVectorCostFactor()
: 1;
return BaseCost * LT.first;
}
int ARMTTIImpl::getInterleavedMemoryOpCost(
unsigned Opcode, Type *VecTy, unsigned Factor, ArrayRef<unsigned> Indices,
unsigned Alignment, unsigned AddressSpace, bool UseMaskForCond,
bool UseMaskForGaps) {
assert(Factor >= 2 && "Invalid interleave factor");
assert(isa<VectorType>(VecTy) && "Expect a vector type");
// vldN/vstN doesn't support vector types of i64/f64 element.
bool EltIs64Bits = DL.getTypeSizeInBits(VecTy->getScalarType()) == 64;
if (Factor <= TLI->getMaxSupportedInterleaveFactor() && !EltIs64Bits &&
!UseMaskForCond && !UseMaskForGaps) {
unsigned NumElts = VecTy->getVectorNumElements();
auto *SubVecTy = VectorType::get(VecTy->getScalarType(), NumElts / Factor);
// vldN/vstN only support legal vector types of size 64 or 128 in bits.
// Accesses having vector types that are a multiple of 128 bits can be
// matched to more than one vldN/vstN instruction.
int BaseCost = ST->hasMVEIntegerOps() ? ST->getMVEVectorCostFactor() : 1;
if (NumElts % Factor == 0 &&
TLI->isLegalInterleavedAccessType(Factor, SubVecTy, DL))
return Factor * BaseCost * TLI->getNumInterleavedAccesses(SubVecTy, DL);
// Some smaller than legal interleaved patterns are cheap as we can make
// use of the vmovn or vrev patterns to interleave a standard load. This is
// true for v4i8, v8i8 and v4i16 at least (but not for v4f16 as it is
// promoted differently). The cost of 2 here is then a load and vrev or
// vmovn.
if (ST->hasMVEIntegerOps() && Factor == 2 && NumElts / Factor > 2 &&
VecTy->isIntOrIntVectorTy() && DL.getTypeSizeInBits(SubVecTy) <= 64)
return 2 * BaseCost;
}
return BaseT::getInterleavedMemoryOpCost(Opcode, VecTy, Factor, Indices,
Alignment, AddressSpace,
UseMaskForCond, UseMaskForGaps);
}
bool ARMTTIImpl::isLoweredToCall(const Function *F) {
if (!F->isIntrinsic())
BaseT::isLoweredToCall(F);
// Assume all Arm-specific intrinsics map to an instruction.
if (F->getName().startswith("llvm.arm"))
return false;
switch (F->getIntrinsicID()) {
default: break;
case Intrinsic::powi:
case Intrinsic::sin:
case Intrinsic::cos:
case Intrinsic::pow:
case Intrinsic::log:
case Intrinsic::log10:
case Intrinsic::log2:
case Intrinsic::exp:
case Intrinsic::exp2:
return true;
case Intrinsic::sqrt:
case Intrinsic::fabs:
case Intrinsic::copysign:
case Intrinsic::floor:
case Intrinsic::ceil:
case Intrinsic::trunc:
case Intrinsic::rint:
case Intrinsic::nearbyint:
case Intrinsic::round:
case Intrinsic::canonicalize:
case Intrinsic::lround:
case Intrinsic::llround:
case Intrinsic::lrint:
case Intrinsic::llrint:
if (F->getReturnType()->isDoubleTy() && !ST->hasFP64())
return true;
if (F->getReturnType()->isHalfTy() && !ST->hasFullFP16())
return true;
// Some operations can be handled by vector instructions and assume
// unsupported vectors will be expanded into supported scalar ones.
// TODO Handle scalar operations properly.
return !ST->hasFPARMv8Base() && !ST->hasVFP2Base();
case Intrinsic::masked_store:
case Intrinsic::masked_load:
case Intrinsic::masked_gather:
case Intrinsic::masked_scatter:
return !ST->hasMVEIntegerOps();
case Intrinsic::sadd_with_overflow:
case Intrinsic::uadd_with_overflow:
case Intrinsic::ssub_with_overflow:
case Intrinsic::usub_with_overflow:
case Intrinsic::sadd_sat:
case Intrinsic::uadd_sat:
case Intrinsic::ssub_sat:
case Intrinsic::usub_sat:
return false;
}
return BaseT::isLoweredToCall(F);
}
bool ARMTTIImpl::isHardwareLoopProfitable(Loop *L, ScalarEvolution &SE,
AssumptionCache &AC,
TargetLibraryInfo *LibInfo,
HardwareLoopInfo &HWLoopInfo) {
// Low-overhead branches are only supported in the 'low-overhead branch'
// extension of v8.1-m.
if (!ST->hasLOB() || DisableLowOverheadLoops)
return false;
if (!SE.hasLoopInvariantBackedgeTakenCount(L))
return false;
const SCEV *BackedgeTakenCount = SE.getBackedgeTakenCount(L);
if (isa<SCEVCouldNotCompute>(BackedgeTakenCount))
return false;
const SCEV *TripCountSCEV =
SE.getAddExpr(BackedgeTakenCount,
SE.getOne(BackedgeTakenCount->getType()));
// We need to store the trip count in LR, a 32-bit register.
if (SE.getUnsignedRangeMax(TripCountSCEV).getBitWidth() > 32)
return false;
// Making a call will trash LR and clear LO_BRANCH_INFO, so there's little
// point in generating a hardware loop if that's going to happen.
auto MaybeCall = [this](Instruction &I) {
const ARMTargetLowering *TLI = getTLI();
unsigned ISD = TLI->InstructionOpcodeToISD(I.getOpcode());
EVT VT = TLI->getValueType(DL, I.getType(), true);
if (TLI->getOperationAction(ISD, VT) == TargetLowering::LibCall)
return true;
// Check if an intrinsic will be lowered to a call and assume that any
// other CallInst will generate a bl.
if (auto *Call = dyn_cast<CallInst>(&I)) {
if (isa<IntrinsicInst>(Call)) {
if (const Function *F = Call->getCalledFunction())
return isLoweredToCall(F);
}
return true;
}
// FPv5 provides conversions between integer, double-precision,
// single-precision, and half-precision formats.
switch (I.getOpcode()) {
default:
break;
case Instruction::FPToSI:
case Instruction::FPToUI:
case Instruction::SIToFP:
case Instruction::UIToFP:
case Instruction::FPTrunc:
case Instruction::FPExt:
return !ST->hasFPARMv8Base();
}
// FIXME: Unfortunately the approach of checking the Operation Action does
// not catch all cases of Legalization that use library calls. Our
// Legalization step categorizes some transformations into library calls as
// Custom, Expand or even Legal when doing type legalization. So for now
// we have to special case for instance the SDIV of 64bit integers and the
// use of floating point emulation.
if (VT.isInteger() && VT.getSizeInBits() >= 64) {
switch (ISD) {
default:
break;
case ISD::SDIV:
case ISD::UDIV:
case ISD::SREM:
case ISD::UREM:
case ISD::SDIVREM:
case ISD::UDIVREM:
return true;
}
}
// Assume all other non-float operations are supported.
if (!VT.isFloatingPoint())
return false;
// We'll need a library call to handle most floats when using soft.
if (TLI->useSoftFloat()) {
switch (I.getOpcode()) {
default:
return true;
case Instruction::Alloca:
case Instruction::Load:
case Instruction::Store:
case Instruction::Select:
case Instruction::PHI:
return false;
}
}
// We'll need a libcall to perform double precision operations on a single
// precision only FPU.
if (I.getType()->isDoubleTy() && !ST->hasFP64())
return true;
// Likewise for half precision arithmetic.
if (I.getType()->isHalfTy() && !ST->hasFullFP16())
return true;
return false;
};
auto IsHardwareLoopIntrinsic = [](Instruction &I) {
if (auto *Call = dyn_cast<IntrinsicInst>(&I)) {
switch (Call->getIntrinsicID()) {
default:
break;
case Intrinsic::set_loop_iterations:
case Intrinsic::test_set_loop_iterations:
case Intrinsic::loop_decrement:
case Intrinsic::loop_decrement_reg:
return true;
}
}
return false;
};
// Scan the instructions to see if there's any that we know will turn into a
// call or if this loop is already a low-overhead loop.
auto ScanLoop = [&](Loop *L) {
for (auto *BB : L->getBlocks()) {
for (auto &I : *BB) {
if (MaybeCall(I) || IsHardwareLoopIntrinsic(I))
return false;
}
}
return true;
};
// Visit inner loops.
for (auto Inner : *L)
if (!ScanLoop(Inner))
return false;
if (!ScanLoop(L))
return false;
// TODO: Check whether the trip count calculation is expensive. If L is the
// inner loop but we know it has a low trip count, calculating that trip
// count (in the parent loop) may be detrimental.
LLVMContext &C = L->getHeader()->getContext();
HWLoopInfo.CounterInReg = true;
HWLoopInfo.IsNestingLegal = false;
HWLoopInfo.PerformEntryTest = true;
HWLoopInfo.CountType = Type::getInt32Ty(C);
HWLoopInfo.LoopDecrement = ConstantInt::get(HWLoopInfo.CountType, 1);
return true;
}
static bool canTailPredicateInstruction(Instruction &I, int &ICmpCount) {
// We don't allow icmp's, and because we only look at single block loops,
// we simply count the icmps, i.e. there should only be 1 for the backedge.
if (isa<ICmpInst>(&I) && ++ICmpCount > 1)
return false;
if (isa<FCmpInst>(&I))
return false;
// We could allow extending/narrowing FP loads/stores, but codegen is
// too inefficient so reject this for now.
if (isa<FPExtInst>(&I) || isa<FPTruncInst>(&I))
return false;
// Extends have to be extending-loads
if (isa<SExtInst>(&I) || isa<ZExtInst>(&I) )
if (!I.getOperand(0)->hasOneUse() || !isa<LoadInst>(I.getOperand(0)))
return false;
// Truncs have to be narrowing-stores
if (isa<TruncInst>(&I) )
if (!I.hasOneUse() || !isa<StoreInst>(*I.user_begin()))
return false;
return true;
}
// To set up a tail-predicated loop, we need to know the total number of
// elements processed by that loop. Thus, we need to determine the element
// size and:
// 1) it should be uniform for all operations in the vector loop, so we
// e.g. don't want any widening/narrowing operations.
// 2) it should be smaller than i64s because we don't have vector operations
// that work on i64s.
// 3) we don't want elements to be reversed or shuffled, to make sure the
// tail-predication masks/predicates the right lanes.
//
static bool canTailPredicateLoop(Loop *L, LoopInfo *LI, ScalarEvolution &SE,
const DataLayout &DL,
const LoopAccessInfo *LAI) {
PredicatedScalarEvolution PSE = LAI->getPSE();
int ICmpCount = 0;
int Stride = 0;
LLVM_DEBUG(dbgs() << "tail-predication: checking allowed instructions\n");
SmallVector<Instruction *, 16> LoadStores;
for (BasicBlock *BB : L->blocks()) {
for (Instruction &I : BB->instructionsWithoutDebug()) {
if (isa<PHINode>(&I))
continue;
if (!canTailPredicateInstruction(I, ICmpCount)) {
LLVM_DEBUG(dbgs() << "Instruction not allowed: "; I.dump());
return false;
}
Type *T = I.getType();
if (T->isPointerTy())
T = T->getPointerElementType();
if (T->getScalarSizeInBits() > 32) {
LLVM_DEBUG(dbgs() << "Unsupported Type: "; T->dump());
return false;
}
if (isa<StoreInst>(I) || isa<LoadInst>(I)) {
Value *Ptr = isa<LoadInst>(I) ? I.getOperand(0) : I.getOperand(1);
int64_t NextStride = getPtrStride(PSE, Ptr, L);
// TODO: for now only allow consecutive strides of 1. We could support
// other strides as long as it is uniform, but let's keep it simple for
// now.
if (Stride == 0 && NextStride == 1) {
Stride = NextStride;
continue;
}
if (Stride != NextStride) {
LLVM_DEBUG(dbgs() << "Different strides found, can't "
"tail-predicate\n.");
return false;
}
}
}
}
LLVM_DEBUG(dbgs() << "tail-predication: all instructions allowed!\n");
return true;
}
bool ARMTTIImpl::preferPredicateOverEpilogue(Loop *L, LoopInfo *LI,
ScalarEvolution &SE,
AssumptionCache &AC,
TargetLibraryInfo *TLI,
DominatorTree *DT,
const LoopAccessInfo *LAI) {
if (DisableTailPredication)
return false;
// Creating a predicated vector loop is the first step for generating a
// tail-predicated hardware loop, for which we need the MVE masked
// load/stores instructions:
if (!ST->hasMVEIntegerOps())
return false;
// For now, restrict this to single block loops.
if (L->getNumBlocks() > 1) {
LLVM_DEBUG(dbgs() << "preferPredicateOverEpilogue: not a single block "
"loop.\n");
return false;
}
assert(L->empty() && "preferPredicateOverEpilogue: inner-loop expected");
HardwareLoopInfo HWLoopInfo(L);
if (!HWLoopInfo.canAnalyze(*LI)) {
LLVM_DEBUG(dbgs() << "preferPredicateOverEpilogue: hardware-loop is not "
"analyzable.\n");
return false;
}
// This checks if we have the low-overhead branch architecture
// extension, and if we will create a hardware-loop:
if (!isHardwareLoopProfitable(L, SE, AC, TLI, HWLoopInfo)) {
LLVM_DEBUG(dbgs() << "preferPredicateOverEpilogue: hardware-loop is not "
"profitable.\n");
return false;
}
if (!HWLoopInfo.isHardwareLoopCandidate(SE, *LI, *DT)) {
LLVM_DEBUG(dbgs() << "preferPredicateOverEpilogue: hardware-loop is not "
"a candidate.\n");
return false;
}
return canTailPredicateLoop(L, LI, SE, DL, LAI);
}
void ARMTTIImpl::getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
TTI::UnrollingPreferences &UP) {
// Only currently enable these preferences for M-Class cores.
if (!ST->isMClass())
return BasicTTIImplBase::getUnrollingPreferences(L, SE, UP);
// Disable loop unrolling for Oz and Os.
UP.OptSizeThreshold = 0;
UP.PartialOptSizeThreshold = 0;
if (L->getHeader()->getParent()->hasOptSize())
return;
// Only enable on Thumb-2 targets.
if (!ST->isThumb2())
return;
SmallVector<BasicBlock*, 4> ExitingBlocks;
L->getExitingBlocks(ExitingBlocks);
LLVM_DEBUG(dbgs() << "Loop has:\n"
<< "Blocks: " << L->getNumBlocks() << "\n"
<< "Exit blocks: " << ExitingBlocks.size() << "\n");
// Only allow another exit other than the latch. This acts as an early exit
// as it mirrors the profitability calculation of the runtime unroller.
if (ExitingBlocks.size() > 2)
return;
// Limit the CFG of the loop body for targets with a branch predictor.
// Allowing 4 blocks permits if-then-else diamonds in the body.
if (ST->hasBranchPredictor() && L->getNumBlocks() > 4)
return;
// Scan the loop: don't unroll loops with calls as this could prevent
// inlining.
unsigned Cost = 0;
for (auto *BB : L->getBlocks()) {
for (auto &I : *BB) {
// Don't unroll vectorised loop. MVE does not benefit from it as much as
// scalar code.
if (I.getType()->isVectorTy())
return;
if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
ImmutableCallSite CS(&I);
if (const Function *F = CS.getCalledFunction()) {
if (!isLoweredToCall(F))
continue;
}
return;
}
SmallVector<const Value*, 4> Operands(I.value_op_begin(),
I.value_op_end());
Cost += getUserCost(&I, Operands);
}
}
LLVM_DEBUG(dbgs() << "Cost of loop: " << Cost << "\n");
UP.Partial = true;
UP.Runtime = true;
UP.UpperBound = true;
UP.UnrollRemainder = true;
UP.DefaultUnrollRuntimeCount = 4;
UP.UnrollAndJam = true;
UP.UnrollAndJamInnerLoopThreshold = 60;
// Force unrolling small loops can be very useful because of the branch
// taken cost of the backedge.
if (Cost < 12)
UP.Force = true;
}
bool ARMTTIImpl::useReductionIntrinsic(unsigned Opcode, Type *Ty,
TTI::ReductionFlags Flags) const {
assert(isa<VectorType>(Ty) && "Expected Ty to be a vector type");
unsigned ScalarBits = Ty->getScalarSizeInBits();
if (!ST->hasMVEIntegerOps())
return false;
switch (Opcode) {
case Instruction::FAdd:
case Instruction::FMul:
case Instruction::And:
case Instruction::Or:
case Instruction::Xor:
case Instruction::Mul:
case Instruction::FCmp:
return false;
case Instruction::ICmp:
case Instruction::Add:
return ScalarBits < 64 && ScalarBits * Ty->getVectorNumElements() == 128;
default:
llvm_unreachable("Unhandled reduction opcode");
}
return false;
}