//===-- X86TargetTransformInfo.cpp - X86 specific TTI pass ----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
/// \file
/// This file implements a TargetTransformInfo analysis pass specific to the
/// X86 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.
///
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "x86tti"
#include "X86.h"
#include "X86TargetMachine.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/Support/Debug.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/CostTable.h"
using namespace llvm;
// Declare the pass initialization routine locally as target-specific passes
// don't havve a target-wide initialization entry point, and so we rely on the
// pass constructor initialization.
namespace llvm {
void initializeX86TTIPass(PassRegistry &);
}
namespace {
class X86TTI : public ImmutablePass, public TargetTransformInfo {
const X86TargetMachine *TM;
const X86Subtarget *ST;
const X86TargetLowering *TLI;
/// Estimate the overhead of scalarizing an instruction. Insert and Extract
/// are set if the result needs to be inserted and/or extracted from vectors.
unsigned getScalarizationOverhead(Type *Ty, bool Insert, bool Extract) const;
public:
X86TTI() : ImmutablePass(ID), TM(0), ST(0), TLI(0) {
llvm_unreachable("This pass cannot be directly constructed");
}
X86TTI(const X86TargetMachine *TM)
: ImmutablePass(ID), TM(TM), ST(TM->getSubtargetImpl()),
TLI(TM->getTargetLowering()) {
initializeX86TTIPass(*PassRegistry::getPassRegistry());
}
virtual void initializePass() {
pushTTIStack(this);
}
virtual void finalizePass() {
popTTIStack();
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
TargetTransformInfo::getAnalysisUsage(AU);
}
/// Pass identification.
static char ID;
/// Provide necessary pointer adjustments for the two base classes.
virtual void *getAdjustedAnalysisPointer(const void *ID) {
if (ID == &TargetTransformInfo::ID)
return (TargetTransformInfo*)this;
return this;
}
/// \name Scalar TTI Implementations
/// @{
virtual PopcntSupportKind getPopcntSupport(unsigned TyWidth) const;
/// @}
/// \name Vector TTI Implementations
/// @{
virtual unsigned getNumberOfRegisters(bool Vector) const;
virtual unsigned getRegisterBitWidth(bool Vector) const;
virtual unsigned getMaximumUnrollFactor() const;
virtual unsigned getArithmeticInstrCost(unsigned Opcode, Type *Ty) const;
virtual unsigned getShuffleCost(ShuffleKind Kind, Type *Tp,
int Index, Type *SubTp) const;
virtual unsigned getCastInstrCost(unsigned Opcode, Type *Dst,
Type *Src) const;
virtual unsigned getCmpSelInstrCost(unsigned Opcode, Type *ValTy,
Type *CondTy) const;
virtual unsigned getVectorInstrCost(unsigned Opcode, Type *Val,
unsigned Index) const;
virtual unsigned getMemoryOpCost(unsigned Opcode, Type *Src,
unsigned Alignment,
unsigned AddressSpace) const;
/// @}
};
} // end anonymous namespace
INITIALIZE_AG_PASS(X86TTI, TargetTransformInfo, "x86tti",
"X86 Target Transform Info", true, true, false)
char X86TTI::ID = 0;
ImmutablePass *
llvm::createX86TargetTransformInfoPass(const X86TargetMachine *TM) {
return new X86TTI(TM);
}
//===----------------------------------------------------------------------===//
//
// X86 cost model.
//
//===----------------------------------------------------------------------===//
X86TTI::PopcntSupportKind X86TTI::getPopcntSupport(unsigned TyWidth) const {
assert(isPowerOf2_32(TyWidth) && "Ty width must be power of 2");
// TODO: Currently the __builtin_popcount() implementation using SSE3
// instructions is inefficient. Once the problem is fixed, we should
// call ST->hasSSE3() instead of ST->hasSSE4().
return ST->hasSSE41() ? PSK_FastHardware : PSK_Software;
}
unsigned X86TTI::getNumberOfRegisters(bool Vector) const {
if (Vector && !ST->hasSSE1())
return 0;
if (ST->is64Bit())
return 16;
return 8;
}
unsigned X86TTI::getRegisterBitWidth(bool Vector) const {
if (Vector) {
if (ST->hasAVX()) return 256;
if (ST->hasSSE1()) return 128;
return 0;
}
if (ST->is64Bit())
return 64;
return 32;
}
unsigned X86TTI::getMaximumUnrollFactor() const {
if (ST->isAtom())
return 1;
// Sandybridge and Haswell have multiple execution ports and pipelined
// vector units.
if (ST->hasAVX())
return 4;
return 2;
}
unsigned X86TTI::getArithmeticInstrCost(unsigned Opcode, Type *Ty) const {
// Legalize the type.
std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(Ty);
int ISD = TLI->InstructionOpcodeToISD(Opcode);
assert(ISD && "Invalid opcode");
static const CostTblEntry<MVT> AVX1CostTable[] = {
// We don't have to scalarize unsupported ops. We can issue two half-sized
// operations and we only need to extract the upper YMM half.
// Two ops + 1 extract + 1 insert = 4.
{ ISD::MUL, MVT::v8i32, 4 },
{ ISD::SUB, MVT::v8i32, 4 },
{ ISD::ADD, MVT::v8i32, 4 },
{ ISD::SUB, MVT::v4i64, 4 },
{ ISD::ADD, MVT::v4i64, 4 },
// A v4i64 multiply is custom lowered as two split v2i64 vectors that then
// are lowered as a series of long multiplies(3), shifts(4) and adds(2)
// Because we believe v4i64 to be a legal type, we must also include the
// split factor of two in the cost table. Therefore, the cost here is 18
// instead of 9.
{ ISD::MUL, MVT::v4i64, 18 },
};
// Look for AVX1 lowering tricks.
if (ST->hasAVX() && !ST->hasAVX2()) {
int Idx = CostTableLookup<MVT>(AVX1CostTable, array_lengthof(AVX1CostTable),
ISD, LT.second);
if (Idx != -1)
return LT.first * AVX1CostTable[Idx].Cost;
}
// Custom lowering of vectors.
static const CostTblEntry<MVT> CustomLowered[] = {
// A v2i64/v4i64 and multiply is custom lowered as a series of long
// multiplies(3), shifts(4) and adds(2).
{ ISD::MUL, MVT::v2i64, 9 },
{ ISD::MUL, MVT::v4i64, 9 },
};
int Idx = CostTableLookup<MVT>(CustomLowered, array_lengthof(CustomLowered),
ISD, LT.second);
if (Idx != -1)
return LT.first * CustomLowered[Idx].Cost;
// Special lowering of v4i32 mul on sse2, sse3: Lower v4i32 mul as 2x shuffle,
// 2x pmuludq, 2x shuffle.
if (ISD == ISD::MUL && LT.second == MVT::v4i32 && ST->hasSSE2() &&
!ST->hasSSE41())
return 6;
// Fallback to the default implementation.
return TargetTransformInfo::getArithmeticInstrCost(Opcode, Ty);
}
unsigned X86TTI::getShuffleCost(ShuffleKind Kind, Type *Tp, int Index,
Type *SubTp) const {
// We only estimate the cost of reverse shuffles.
if (Kind != SK_Reverse)
return TargetTransformInfo::getShuffleCost(Kind, Tp, Index, SubTp);
std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(Tp);
unsigned Cost = 1;
if (LT.second.getSizeInBits() > 128)
Cost = 3; // Extract + insert + copy.
// Multiple by the number of parts.
return Cost * LT.first;
}
unsigned X86TTI::getCastInstrCost(unsigned Opcode, Type *Dst, Type *Src) const {
int ISD = TLI->InstructionOpcodeToISD(Opcode);
assert(ISD && "Invalid opcode");
EVT SrcTy = TLI->getValueType(Src);
EVT DstTy = TLI->getValueType(Dst);
if (!SrcTy.isSimple() || !DstTy.isSimple())
return TargetTransformInfo::getCastInstrCost(Opcode, Dst, Src);
static const TypeConversionCostTblEntry<MVT> AVXConversionTbl[] = {
{ ISD::SIGN_EXTEND, MVT::v8i32, MVT::v8i16, 1 },
{ ISD::ZERO_EXTEND, MVT::v8i32, MVT::v8i16, 1 },
{ ISD::SIGN_EXTEND, MVT::v4i64, MVT::v4i32, 1 },
{ ISD::ZERO_EXTEND, MVT::v4i64, MVT::v4i32, 1 },
{ ISD::TRUNCATE, MVT::v4i32, MVT::v4i64, 1 },
{ ISD::TRUNCATE, MVT::v8i16, MVT::v8i32, 1 },
{ ISD::SINT_TO_FP, MVT::v8f32, MVT::v8i8, 1 },
{ ISD::SINT_TO_FP, MVT::v4f32, MVT::v4i8, 1 },
{ ISD::UINT_TO_FP, MVT::v8f32, MVT::v8i8, 1 },
{ ISD::UINT_TO_FP, MVT::v4f32, MVT::v4i8, 1 },
{ ISD::FP_TO_SINT, MVT::v8i8, MVT::v8f32, 1 },
{ ISD::FP_TO_SINT, MVT::v4i8, MVT::v4f32, 1 },
{ ISD::ZERO_EXTEND, MVT::v8i32, MVT::v8i1, 6 },
{ ISD::SIGN_EXTEND, MVT::v8i32, MVT::v8i1, 9 },
{ ISD::SIGN_EXTEND, MVT::v4i64, MVT::v4i1, 8 },
{ ISD::SIGN_EXTEND, MVT::v4i64, MVT::v4i8, 8 },
{ ISD::SIGN_EXTEND, MVT::v4i64, MVT::v4i16, 8 },
{ ISD::TRUNCATE, MVT::v8i32, MVT::v8i64, 3 },
};
if (ST->hasAVX()) {
int Idx = ConvertCostTableLookup<MVT>(AVXConversionTbl,
array_lengthof(AVXConversionTbl),
ISD, DstTy.getSimpleVT(), SrcTy.getSimpleVT());
if (Idx != -1)
return AVXConversionTbl[Idx].Cost;
}
return TargetTransformInfo::getCastInstrCost(Opcode, Dst, Src);
}
unsigned X86TTI::getCmpSelInstrCost(unsigned Opcode, Type *ValTy,
Type *CondTy) const {
// Legalize the type.
std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(ValTy);
MVT MTy = LT.second;
int ISD = TLI->InstructionOpcodeToISD(Opcode);
assert(ISD && "Invalid opcode");
static const CostTblEntry<MVT> SSE42CostTbl[] = {
{ ISD::SETCC, MVT::v2f64, 1 },
{ ISD::SETCC, MVT::v4f32, 1 },
{ ISD::SETCC, MVT::v2i64, 1 },
{ ISD::SETCC, MVT::v4i32, 1 },
{ ISD::SETCC, MVT::v8i16, 1 },
{ ISD::SETCC, MVT::v16i8, 1 },
};
static const CostTblEntry<MVT> AVX1CostTbl[] = {
{ ISD::SETCC, MVT::v4f64, 1 },
{ ISD::SETCC, MVT::v8f32, 1 },
// AVX1 does not support 8-wide integer compare.
{ ISD::SETCC, MVT::v4i64, 4 },
{ ISD::SETCC, MVT::v8i32, 4 },
{ ISD::SETCC, MVT::v16i16, 4 },
{ ISD::SETCC, MVT::v32i8, 4 },
};
static const CostTblEntry<MVT> AVX2CostTbl[] = {
{ ISD::SETCC, MVT::v4i64, 1 },
{ ISD::SETCC, MVT::v8i32, 1 },
{ ISD::SETCC, MVT::v16i16, 1 },
{ ISD::SETCC, MVT::v32i8, 1 },
};
if (ST->hasAVX2()) {
int Idx = CostTableLookup<MVT>(AVX2CostTbl, array_lengthof(AVX2CostTbl), ISD, MTy);
if (Idx != -1)
return LT.first * AVX2CostTbl[Idx].Cost;
}
if (ST->hasAVX()) {
int Idx = CostTableLookup<MVT>(AVX1CostTbl, array_lengthof(AVX1CostTbl), ISD, MTy);
if (Idx != -1)
return LT.first * AVX1CostTbl[Idx].Cost;
}
if (ST->hasSSE42()) {
int Idx = CostTableLookup<MVT>(SSE42CostTbl, array_lengthof(SSE42CostTbl), ISD, MTy);
if (Idx != -1)
return LT.first * SSE42CostTbl[Idx].Cost;
}
return TargetTransformInfo::getCmpSelInstrCost(Opcode, ValTy, CondTy);
}
unsigned X86TTI::getVectorInstrCost(unsigned Opcode, Type *Val,
unsigned Index) const {
assert(Val->isVectorTy() && "This must be a vector type");
if (Index != -1U) {
// Legalize the type.
std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(Val);
// This type is legalized to a scalar type.
if (!LT.second.isVector())
return 0;
// The type may be split. Normalize the index to the new type.
unsigned Width = LT.second.getVectorNumElements();
Index = Index % Width;
// Floating point scalars are already located in index #0.
if (Val->getScalarType()->isFloatingPointTy() && Index == 0)
return 0;
}
return TargetTransformInfo::getVectorInstrCost(Opcode, Val, Index);
}
unsigned X86TTI::getMemoryOpCost(unsigned Opcode, Type *Src, unsigned Alignment,
unsigned AddressSpace) const {
// Legalize the type.
std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(Src);
assert((Opcode == Instruction::Load || Opcode == Instruction::Store) &&
"Invalid Opcode");
// Each load/store unit costs 1.
unsigned Cost = LT.first * 1;
// On Sandybridge 256bit load/stores are double pumped
// (but not on Haswell).
if (LT.second.getSizeInBits() > 128 && !ST->hasAVX2())
Cost*=2;
return Cost;
}