OSchip
/
llvm-project
mirror of https://github.com/THU-DSP-LAB/llvm-project.git
13
0
Fork 6
Code Issues Packages Projects Releases Wiki Activity
llvm-project/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp

1210 lines
44 KiB
C++
Raw Blame History

//===-- llvm/CodeGen/GlobalISel/LegalizerHelper.cpp -----------------------===//
//
// 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 the LegalizerHelper class to legalize
/// individual instructions and the LegalizeMachineIR wrapper pass for the
/// primary legalization.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/GlobalISel/LegalizerHelper.h"
#include "llvm/CodeGen/GlobalISel/CallLowering.h"
#include "llvm/CodeGen/GlobalISel/LegalizerInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#define DEBUG_TYPE "legalizer"
using namespace llvm;
using namespace LegalizeActions;
LegalizerHelper::LegalizerHelper(MachineFunction &MF)
: MRI(MF.getRegInfo()), LI(*MF.getSubtarget().getLegalizerInfo()) {
MIRBuilder.setMF(MF);
}
LegalizerHelper::LegalizerHelper(MachineFunction &MF, const LegalizerInfo &LI)
: MRI(MF.getRegInfo()), LI(LI) {
MIRBuilder.setMF(MF);
}
LegalizerHelper::LegalizeResult
LegalizerHelper::legalizeInstrStep(MachineInstr &MI) {
LLVM_DEBUG(dbgs() << "Legalizing: "; MI.print(dbgs()));
auto Step = LI.getAction(MI, MRI);
switch (Step.Action) {
case Legal:
LLVM_DEBUG(dbgs() << ".. Already legal\n");
return AlreadyLegal;
case Libcall:
LLVM_DEBUG(dbgs() << ".. Convert to libcall\n");
return libcall(MI);
case NarrowScalar:
LLVM_DEBUG(dbgs() << ".. Narrow scalar\n");
return narrowScalar(MI, Step.TypeIdx, Step.NewType);
case WidenScalar:
LLVM_DEBUG(dbgs() << ".. Widen scalar\n");
return widenScalar(MI, Step.TypeIdx, Step.NewType);
case Lower:
LLVM_DEBUG(dbgs() << ".. Lower\n");
return lower(MI, Step.TypeIdx, Step.NewType);
case FewerElements:
LLVM_DEBUG(dbgs() << ".. Reduce number of elements\n");
return fewerElementsVector(MI, Step.TypeIdx, Step.NewType);
case Custom:
LLVM_DEBUG(dbgs() << ".. Custom legalization\n");
return LI.legalizeCustom(MI, MRI, MIRBuilder) ? Legalized
: UnableToLegalize;
default:
LLVM_DEBUG(dbgs() << ".. Unable to legalize\n");
return UnableToLegalize;
}
}
void LegalizerHelper::extractParts(unsigned Reg, LLT Ty, int NumParts,
SmallVectorImpl<unsigned> &VRegs) {
for (int i = 0; i < NumParts; ++i)
VRegs.push_back(MRI.createGenericVirtualRegister(Ty));
MIRBuilder.buildUnmerge(VRegs, Reg);
}
static RTLIB::Libcall getRTLibDesc(unsigned Opcode, unsigned Size) {
switch (Opcode) {
case TargetOpcode::G_SDIV:
assert(Size == 32 && "Unsupported size");
return RTLIB::SDIV_I32;
case TargetOpcode::G_UDIV:
assert(Size == 32 && "Unsupported size");
return RTLIB::UDIV_I32;
case TargetOpcode::G_SREM:
assert(Size == 32 && "Unsupported size");
return RTLIB::SREM_I32;
case TargetOpcode::G_UREM:
assert(Size == 32 && "Unsupported size");
return RTLIB::UREM_I32;
case TargetOpcode::G_FADD:
assert((Size == 32 || Size == 64) && "Unsupported size");
return Size == 64 ? RTLIB::ADD_F64 : RTLIB::ADD_F32;
case TargetOpcode::G_FSUB:
assert((Size == 32 || Size == 64) && "Unsupported size");
return Size == 64 ? RTLIB::SUB_F64 : RTLIB::SUB_F32;
case TargetOpcode::G_FMUL:
assert((Size == 32 || Size == 64) && "Unsupported size");
return Size == 64 ? RTLIB::MUL_F64 : RTLIB::MUL_F32;
case TargetOpcode::G_FDIV:
assert((Size == 32 || Size == 64) && "Unsupported size");
return Size == 64 ? RTLIB::DIV_F64 : RTLIB::DIV_F32;
case TargetOpcode::G_FREM:
return Size == 64 ? RTLIB::REM_F64 : RTLIB::REM_F32;
case TargetOpcode::G_FPOW:
return Size == 64 ? RTLIB::POW_F64 : RTLIB::POW_F32;
case TargetOpcode::G_FMA:
assert((Size == 32 || Size == 64) && "Unsupported size");
return Size == 64 ? RTLIB::FMA_F64 : RTLIB::FMA_F32;
}
llvm_unreachable("Unknown libcall function");
}
LegalizerHelper::LegalizeResult
llvm::createLibcall(MachineIRBuilder &MIRBuilder, RTLIB::Libcall Libcall,
const CallLowering::ArgInfo &Result,
ArrayRef<CallLowering::ArgInfo> Args) {
auto &CLI = *MIRBuilder.getMF().getSubtarget().getCallLowering();
auto &TLI = *MIRBuilder.getMF().getSubtarget().getTargetLowering();
const char *Name = TLI.getLibcallName(Libcall);
MIRBuilder.getMF().getFrameInfo().setHasCalls(true);
if (!CLI.lowerCall(MIRBuilder, TLI.getLibcallCallingConv(Libcall),
MachineOperand::CreateES(Name), Result, Args))
return LegalizerHelper::UnableToLegalize;
return LegalizerHelper::Legalized;
}
// Useful for libcalls where all operands have the same type.
static LegalizerHelper::LegalizeResult
simpleLibcall(MachineInstr &MI, MachineIRBuilder &MIRBuilder, unsigned Size,
Type *OpType) {
auto Libcall = getRTLibDesc(MI.getOpcode(), Size);
SmallVector<CallLowering::ArgInfo, 3> Args;
for (unsigned i = 1; i < MI.getNumOperands(); i++)
Args.push_back({MI.getOperand(i).getReg(), OpType});
return createLibcall(MIRBuilder, Libcall, {MI.getOperand(0).getReg(), OpType},
Args);
}
static RTLIB::Libcall getConvRTLibDesc(unsigned Opcode, Type *ToType,
Type *FromType) {
auto ToMVT = MVT::getVT(ToType);
auto FromMVT = MVT::getVT(FromType);
switch (Opcode) {
case TargetOpcode::G_FPEXT:
return RTLIB::getFPEXT(FromMVT, ToMVT);
case TargetOpcode::G_FPTRUNC:
return RTLIB::getFPROUND(FromMVT, ToMVT);
case TargetOpcode::G_FPTOSI:
return RTLIB::getFPTOSINT(FromMVT, ToMVT);
case TargetOpcode::G_FPTOUI:
return RTLIB::getFPTOUINT(FromMVT, ToMVT);
case TargetOpcode::G_SITOFP:
return RTLIB::getSINTTOFP(FromMVT, ToMVT);
case TargetOpcode::G_UITOFP:
return RTLIB::getUINTTOFP(FromMVT, ToMVT);
}
llvm_unreachable("Unsupported libcall function");
}
static LegalizerHelper::LegalizeResult
conversionLibcall(MachineInstr &MI, MachineIRBuilder &MIRBuilder, Type *ToType,
Type *FromType) {
RTLIB::Libcall Libcall = getConvRTLibDesc(MI.getOpcode(), ToType, FromType);
return createLibcall(MIRBuilder, Libcall, {MI.getOperand(0).getReg(), ToType},
{{MI.getOperand(1).getReg(), FromType}});
}
LegalizerHelper::LegalizeResult
LegalizerHelper::libcall(MachineInstr &MI) {
LLT LLTy = MRI.getType(MI.getOperand(0).getReg());
unsigned Size = LLTy.getSizeInBits();
auto &Ctx = MIRBuilder.getMF().getFunction().getContext();
MIRBuilder.setInstr(MI);
switch (MI.getOpcode()) {
default:
return UnableToLegalize;
case TargetOpcode::G_SDIV:
case TargetOpcode::G_UDIV:
case TargetOpcode::G_SREM:
case TargetOpcode::G_UREM: {
Type *HLTy = Type::getInt32Ty(Ctx);
auto Status = simpleLibcall(MI, MIRBuilder, Size, HLTy);
if (Status != Legalized)
return Status;
break;
}
case TargetOpcode::G_FADD:
case TargetOpcode::G_FSUB:
case TargetOpcode::G_FMUL:
case TargetOpcode::G_FDIV:
case TargetOpcode::G_FMA:
case TargetOpcode::G_FPOW:
case TargetOpcode::G_FREM: {
Type *HLTy = Size == 64 ? Type::getDoubleTy(Ctx) : Type::getFloatTy(Ctx);
auto Status = simpleLibcall(MI, MIRBuilder, Size, HLTy);
if (Status != Legalized)
return Status;
break;
}
case TargetOpcode::G_FPEXT: {
// FIXME: Support other floating point types (half, fp128 etc)
unsigned FromSize = MRI.getType(MI.getOperand(1).getReg()).getSizeInBits();
unsigned ToSize = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
if (ToSize != 64 || FromSize != 32)
return UnableToLegalize;
LegalizeResult Status = conversionLibcall(
MI, MIRBuilder, Type::getDoubleTy(Ctx), Type::getFloatTy(Ctx));
if (Status != Legalized)
return Status;
break;
}
case TargetOpcode::G_FPTRUNC: {
// FIXME: Support other floating point types (half, fp128 etc)
unsigned FromSize = MRI.getType(MI.getOperand(1).getReg()).getSizeInBits();
unsigned ToSize = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
if (ToSize != 32 || FromSize != 64)
return UnableToLegalize;
LegalizeResult Status = conversionLibcall(
MI, MIRBuilder, Type::getFloatTy(Ctx), Type::getDoubleTy(Ctx));
if (Status != Legalized)
return Status;
break;
}
case TargetOpcode::G_FPTOSI:
case TargetOpcode::G_FPTOUI: {
// FIXME: Support other types
unsigned FromSize = MRI.getType(MI.getOperand(1).getReg()).getSizeInBits();
unsigned ToSize = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
if (ToSize != 32 || (FromSize != 32 && FromSize != 64))
return UnableToLegalize;
LegalizeResult Status = conversionLibcall(
MI, MIRBuilder, Type::getInt32Ty(Ctx),
FromSize == 64 ? Type::getDoubleTy(Ctx) : Type::getFloatTy(Ctx));
if (Status != Legalized)
return Status;
break;
}
case TargetOpcode::G_SITOFP:
case TargetOpcode::G_UITOFP: {
// FIXME: Support other types
unsigned FromSize = MRI.getType(MI.getOperand(1).getReg()).getSizeInBits();
unsigned ToSize = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
if (FromSize != 32 || (ToSize != 32 && ToSize != 64))
return UnableToLegalize;
LegalizeResult Status = conversionLibcall(
MI, MIRBuilder,
ToSize == 64 ? Type::getDoubleTy(Ctx) : Type::getFloatTy(Ctx),
Type::getInt32Ty(Ctx));
if (Status != Legalized)
return Status;
break;
}
}
MI.eraseFromParent();
return Legalized;
}
LegalizerHelper::LegalizeResult LegalizerHelper::narrowScalar(MachineInstr &MI,
unsigned TypeIdx,
LLT NarrowTy) {
// FIXME: Don't know how to handle secondary types yet.
if (TypeIdx != 0 && MI.getOpcode() != TargetOpcode::G_EXTRACT)
return UnableToLegalize;
MIRBuilder.setInstr(MI);
uint64_t SizeOp0 = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
uint64_t NarrowSize = NarrowTy.getSizeInBits();
switch (MI.getOpcode()) {
default:
return UnableToLegalize;
case TargetOpcode::G_IMPLICIT_DEF: {
// FIXME: add support for when SizeOp0 isn't an exact multiple of
// NarrowSize.
if (SizeOp0 % NarrowSize != 0)
return UnableToLegalize;
int NumParts = SizeOp0 / NarrowSize;
SmallVector<unsigned, 2> DstRegs;
for (int i = 0; i < NumParts; ++i)
DstRegs.push_back(
MIRBuilder.buildUndef(NarrowTy)->getOperand(0).getReg());
MIRBuilder.buildMerge(MI.getOperand(0).getReg(), DstRegs);
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_ADD: {
// FIXME: add support for when SizeOp0 isn't an exact multiple of
// NarrowSize.
if (SizeOp0 % NarrowSize != 0)
return UnableToLegalize;
// Expand in terms of carry-setting/consuming G_ADDE instructions.
int NumParts = SizeOp0 / NarrowTy.getSizeInBits();
SmallVector<unsigned, 2> Src1Regs, Src2Regs, DstRegs;
extractParts(MI.getOperand(1).getReg(), NarrowTy, NumParts, Src1Regs);
extractParts(MI.getOperand(2).getReg(), NarrowTy, NumParts, Src2Regs);
unsigned CarryIn = MRI.createGenericVirtualRegister(LLT::scalar(1));
MIRBuilder.buildConstant(CarryIn, 0);
for (int i = 0; i < NumParts; ++i) {
unsigned DstReg = MRI.createGenericVirtualRegister(NarrowTy);
unsigned CarryOut = MRI.createGenericVirtualRegister(LLT::scalar(1));
MIRBuilder.buildUAdde(DstReg, CarryOut, Src1Regs[i],
Src2Regs[i], CarryIn);
DstRegs.push_back(DstReg);
CarryIn = CarryOut;
}
unsigned DstReg = MI.getOperand(0).getReg();
MIRBuilder.buildMerge(DstReg, DstRegs);
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_EXTRACT: {
if (TypeIdx != 1)
return UnableToLegalize;
int64_t SizeOp1 = MRI.getType(MI.getOperand(1).getReg()).getSizeInBits();
// FIXME: add support for when SizeOp1 isn't an exact multiple of
// NarrowSize.
if (SizeOp1 % NarrowSize != 0)
return UnableToLegalize;
int NumParts = SizeOp1 / NarrowSize;
SmallVector<unsigned, 2> SrcRegs, DstRegs;
SmallVector<uint64_t, 2> Indexes;
extractParts(MI.getOperand(1).getReg(), NarrowTy, NumParts, SrcRegs);
unsigned OpReg = MI.getOperand(0).getReg();
uint64_t OpStart = MI.getOperand(2).getImm();
uint64_t OpSize = MRI.getType(OpReg).getSizeInBits();
for (int i = 0; i < NumParts; ++i) {
unsigned SrcStart = i * NarrowSize;
if (SrcStart + NarrowSize <= OpStart || SrcStart >= OpStart + OpSize) {
// No part of the extract uses this subregister, ignore it.
continue;
} else if (SrcStart == OpStart && NarrowTy == MRI.getType(OpReg)) {
// The entire subregister is extracted, forward the value.
DstRegs.push_back(SrcRegs[i]);
continue;
}
// OpSegStart is where this destination segment would start in OpReg if it
// extended infinitely in both directions.
int64_t ExtractOffset;
uint64_t SegSize;
if (OpStart < SrcStart) {
ExtractOffset = 0;
SegSize = std::min(NarrowSize, OpStart + OpSize - SrcStart);
} else {
ExtractOffset = OpStart - SrcStart;
SegSize = std::min(SrcStart + NarrowSize - OpStart, OpSize);
}
unsigned SegReg = SrcRegs[i];
if (ExtractOffset != 0 || SegSize != NarrowSize) {
// A genuine extract is needed.
SegReg = MRI.createGenericVirtualRegister(LLT::scalar(SegSize));
MIRBuilder.buildExtract(SegReg, SrcRegs[i], ExtractOffset);
}
DstRegs.push_back(SegReg);
}
MIRBuilder.buildMerge(MI.getOperand(0).getReg(), DstRegs);
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_INSERT: {
// FIXME: add support for when SizeOp0 isn't an exact multiple of
// NarrowSize.
if (SizeOp0 % NarrowSize != 0)
return UnableToLegalize;
int NumParts = SizeOp0 / NarrowSize;
SmallVector<unsigned, 2> SrcRegs, DstRegs;
SmallVector<uint64_t, 2> Indexes;
extractParts(MI.getOperand(1).getReg(), NarrowTy, NumParts, SrcRegs);
unsigned OpReg = MI.getOperand(2).getReg();
uint64_t OpStart = MI.getOperand(3).getImm();
uint64_t OpSize = MRI.getType(OpReg).getSizeInBits();
for (int i = 0; i < NumParts; ++i) {
unsigned DstStart = i * NarrowSize;
if (DstStart + NarrowSize <= OpStart || DstStart >= OpStart + OpSize) {
// No part of the insert affects this subregister, forward the original.
DstRegs.push_back(SrcRegs[i]);
continue;
} else if (DstStart == OpStart && NarrowTy == MRI.getType(OpReg)) {
// The entire subregister is defined by this insert, forward the new
// value.
DstRegs.push_back(OpReg);
continue;
}
// OpSegStart is where this destination segment would start in OpReg if it
// extended infinitely in both directions.
int64_t ExtractOffset, InsertOffset;
uint64_t SegSize;
if (OpStart < DstStart) {
InsertOffset = 0;
ExtractOffset = DstStart - OpStart;
SegSize = std::min(NarrowSize, OpStart + OpSize - DstStart);
} else {
InsertOffset = OpStart - DstStart;
ExtractOffset = 0;
SegSize =
std::min(NarrowSize - InsertOffset, OpStart + OpSize - DstStart);
}
unsigned SegReg = OpReg;
if (ExtractOffset != 0 || SegSize != OpSize) {
// A genuine extract is needed.
SegReg = MRI.createGenericVirtualRegister(LLT::scalar(SegSize));
MIRBuilder.buildExtract(SegReg, OpReg, ExtractOffset);
}
unsigned DstReg = MRI.createGenericVirtualRegister(NarrowTy);
MIRBuilder.buildInsert(DstReg, SrcRegs[i], SegReg, InsertOffset);
DstRegs.push_back(DstReg);
}
assert(DstRegs.size() == (unsigned)NumParts && "not all parts covered");
MIRBuilder.buildMerge(MI.getOperand(0).getReg(), DstRegs);
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_LOAD: {
// FIXME: add support for when SizeOp0 isn't an exact multiple of
// NarrowSize.
if (SizeOp0 % NarrowSize != 0)
return UnableToLegalize;
const auto &MMO = **MI.memoperands_begin();
// This implementation doesn't work for atomics. Give up instead of doing
// something invalid.
if (MMO.getOrdering() != AtomicOrdering::NotAtomic ||
MMO.getFailureOrdering() != AtomicOrdering::NotAtomic)
return UnableToLegalize;
int NumParts = SizeOp0 / NarrowSize;
LLT OffsetTy = LLT::scalar(
MRI.getType(MI.getOperand(1).getReg()).getScalarSizeInBits());
SmallVector<unsigned, 2> DstRegs;
for (int i = 0; i < NumParts; ++i) {
unsigned DstReg = MRI.createGenericVirtualRegister(NarrowTy);
unsigned SrcReg = 0;
unsigned Adjustment = i * NarrowSize / 8;
MachineMemOperand *SplitMMO = MIRBuilder.getMF().getMachineMemOperand(
MMO.getPointerInfo().getWithOffset(Adjustment), MMO.getFlags(),
NarrowSize / 8, i == 0 ? MMO.getAlignment() : NarrowSize / 8,
MMO.getAAInfo(), MMO.getRanges(), MMO.getSyncScopeID(),
MMO.getOrdering(), MMO.getFailureOrdering());
MIRBuilder.materializeGEP(SrcReg, MI.getOperand(1).getReg(), OffsetTy,
Adjustment);
MIRBuilder.buildLoad(DstReg, SrcReg, *SplitMMO);
DstRegs.push_back(DstReg);
}
unsigned DstReg = MI.getOperand(0).getReg();
MIRBuilder.buildMerge(DstReg, DstRegs);
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_STORE: {
// FIXME: add support for when SizeOp0 isn't an exact multiple of
// NarrowSize.
if (SizeOp0 % NarrowSize != 0)
return UnableToLegalize;
const auto &MMO = **MI.memoperands_begin();
// This implementation doesn't work for atomics. Give up instead of doing
// something invalid.
if (MMO.getOrdering() != AtomicOrdering::NotAtomic ||
MMO.getFailureOrdering() != AtomicOrdering::NotAtomic)
return UnableToLegalize;
int NumParts = SizeOp0 / NarrowSize;
LLT OffsetTy = LLT::scalar(
MRI.getType(MI.getOperand(1).getReg()).getScalarSizeInBits());
SmallVector<unsigned, 2> SrcRegs;
extractParts(MI.getOperand(0).getReg(), NarrowTy, NumParts, SrcRegs);
for (int i = 0; i < NumParts; ++i) {
unsigned DstReg = 0;
unsigned Adjustment = i * NarrowSize / 8;
MachineMemOperand *SplitMMO = MIRBuilder.getMF().getMachineMemOperand(
MMO.getPointerInfo().getWithOffset(Adjustment), MMO.getFlags(),
NarrowSize / 8, i == 0 ? MMO.getAlignment() : NarrowSize / 8,
MMO.getAAInfo(), MMO.getRanges(), MMO.getSyncScopeID(),
MMO.getOrdering(), MMO.getFailureOrdering());
MIRBuilder.materializeGEP(DstReg, MI.getOperand(1).getReg(), OffsetTy,
Adjustment);
MIRBuilder.buildStore(SrcRegs[i], DstReg, *SplitMMO);
}
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_CONSTANT: {
// FIXME: add support for when SizeOp0 isn't an exact multiple of
// NarrowSize.
if (SizeOp0 % NarrowSize != 0)
return UnableToLegalize;
int NumParts = SizeOp0 / NarrowSize;
const APInt &Cst = MI.getOperand(1).getCImm()->getValue();
LLVMContext &Ctx = MIRBuilder.getMF().getFunction().getContext();
SmallVector<unsigned, 2> DstRegs;
for (int i = 0; i < NumParts; ++i) {
unsigned DstReg = MRI.createGenericVirtualRegister(NarrowTy);
ConstantInt *CI =
ConstantInt::get(Ctx, Cst.lshr(NarrowSize * i).trunc(NarrowSize));
MIRBuilder.buildConstant(DstReg, *CI);
DstRegs.push_back(DstReg);
}
unsigned DstReg = MI.getOperand(0).getReg();
MIRBuilder.buildMerge(DstReg, DstRegs);
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_OR: {
// Legalize bitwise operation:
// A = BinOp<Ty> B, C
// into:
// B1, ..., BN = G_UNMERGE_VALUES B
// C1, ..., CN = G_UNMERGE_VALUES C
// A1 = BinOp<Ty/N> B1, C2
// ...
// AN = BinOp<Ty/N> BN, CN
// A = G_MERGE_VALUES A1, ..., AN
// FIXME: add support for when SizeOp0 isn't an exact multiple of
// NarrowSize.
if (SizeOp0 % NarrowSize != 0)
return UnableToLegalize;
int NumParts = SizeOp0 / NarrowSize;
// List the registers where the destination will be scattered.
SmallVector<unsigned, 2> DstRegs;
// List the registers where the first argument will be split.
SmallVector<unsigned, 2> SrcsReg1;
// List the registers where the second argument will be split.
SmallVector<unsigned, 2> SrcsReg2;
// Create all the temporary registers.
for (int i = 0; i < NumParts; ++i) {
unsigned DstReg = MRI.createGenericVirtualRegister(NarrowTy);
unsigned SrcReg1 = MRI.createGenericVirtualRegister(NarrowTy);
unsigned SrcReg2 = MRI.createGenericVirtualRegister(NarrowTy);
DstRegs.push_back(DstReg);
SrcsReg1.push_back(SrcReg1);
SrcsReg2.push_back(SrcReg2);
}
// Explode the big arguments into smaller chunks.
MIRBuilder.buildUnmerge(SrcsReg1, MI.getOperand(1).getReg());
MIRBuilder.buildUnmerge(SrcsReg2, MI.getOperand(2).getReg());
// Do the operation on each small part.
for (int i = 0; i < NumParts; ++i)
MIRBuilder.buildOr(DstRegs[i], SrcsReg1[i], SrcsReg2[i]);
// Gather the destination registers into the final destination.
unsigned DstReg = MI.getOperand(0).getReg();
MIRBuilder.buildMerge(DstReg, DstRegs);
MI.eraseFromParent();
return Legalized;
}
}
}
void LegalizerHelper::widenScalarSrc(MachineInstr &MI, LLT WideTy,
unsigned OpIdx, unsigned ExtOpcode) {
MachineOperand &MO = MI.getOperand(OpIdx);
auto ExtB = MIRBuilder.buildInstr(ExtOpcode, WideTy, MO.getReg());
MO.setReg(ExtB->getOperand(0).getReg());
}
void LegalizerHelper::widenScalarDst(MachineInstr &MI, LLT WideTy,
unsigned OpIdx, unsigned TruncOpcode) {
MachineOperand &MO = MI.getOperand(OpIdx);
unsigned DstExt = MRI.createGenericVirtualRegister(WideTy);
MIRBuilder.setInsertPt(MIRBuilder.getMBB(), ++MIRBuilder.getInsertPt());
MIRBuilder.buildInstr(TruncOpcode, MO.getReg(), DstExt);
MO.setReg(DstExt);
}
LegalizerHelper::LegalizeResult
LegalizerHelper::widenScalar(MachineInstr &MI, unsigned TypeIdx, LLT WideTy) {
MIRBuilder.setInstr(MI);
switch (MI.getOpcode()) {
default:
return UnableToLegalize;
case TargetOpcode::G_UADDO:
case TargetOpcode::G_USUBO: {
if (TypeIdx == 1)
return UnableToLegalize; // TODO
auto LHSZext = MIRBuilder.buildInstr(TargetOpcode::G_ZEXT, WideTy,
MI.getOperand(2).getReg());
auto RHSZext = MIRBuilder.buildInstr(TargetOpcode::G_ZEXT, WideTy,
MI.getOperand(3).getReg());
unsigned Opcode = MI.getOpcode() == TargetOpcode::G_UADDO
? TargetOpcode::G_ADD
: TargetOpcode::G_SUB;
// Do the arithmetic in the larger type.
auto NewOp = MIRBuilder.buildInstr(Opcode, WideTy, LHSZext, RHSZext);
LLT OrigTy = MRI.getType(MI.getOperand(0).getReg());
APInt Mask = APInt::getAllOnesValue(OrigTy.getSizeInBits());
auto AndOp = MIRBuilder.buildInstr(
TargetOpcode::G_AND, WideTy, NewOp,
MIRBuilder.buildConstant(WideTy, Mask.getZExtValue()));
// There is no overflow if the AndOp is the same as NewOp.
MIRBuilder.buildICmp(CmpInst::ICMP_NE, MI.getOperand(1).getReg(), NewOp,
AndOp);
// Now trunc the NewOp to the original result.
MIRBuilder.buildTrunc(MI.getOperand(0).getReg(), NewOp);
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_CTTZ:
case TargetOpcode::G_CTTZ_ZERO_UNDEF:
case TargetOpcode::G_CTLZ:
case TargetOpcode::G_CTLZ_ZERO_UNDEF:
case TargetOpcode::G_CTPOP: {
// First ZEXT the input.
auto MIBSrc = MIRBuilder.buildZExt(WideTy, MI.getOperand(1).getReg());
LLT CurTy = MRI.getType(MI.getOperand(0).getReg());
if (MI.getOpcode() == TargetOpcode::G_CTTZ) {
// The count is the same in the larger type except if the original
// value was zero. This can be handled by setting the bit just off
// the top of the original type.
auto TopBit =
APInt::getOneBitSet(WideTy.getSizeInBits(), CurTy.getSizeInBits());
MIBSrc = MIRBuilder.buildInstr(
TargetOpcode::G_OR, WideTy, MIBSrc,
MIRBuilder.buildConstant(WideTy, TopBit.getSExtValue()));
}
// Perform the operation at the larger size.
auto MIBNewOp = MIRBuilder.buildInstr(MI.getOpcode(), WideTy, MIBSrc);
// This is already the correct result for CTPOP and CTTZs
if (MI.getOpcode() == TargetOpcode::G_CTLZ ||
MI.getOpcode() == TargetOpcode::G_CTLZ_ZERO_UNDEF) {
// The correct result is NewOp - (Difference in widety and current ty).
unsigned SizeDiff = WideTy.getSizeInBits() - CurTy.getSizeInBits();
MIBNewOp =
MIRBuilder.buildInstr(TargetOpcode::G_SUB, WideTy, MIBNewOp,
MIRBuilder.buildConstant(WideTy, SizeDiff));
}
auto &TII = *MI.getMF()->getSubtarget().getInstrInfo();
// Make the original instruction a trunc now, and update it's source.
MI.setDesc(TII.get(TargetOpcode::G_TRUNC));
MI.getOperand(1).setReg(MIBNewOp->getOperand(0).getReg());
MIRBuilder.recordInsertion(&MI);
return Legalized;
}
case TargetOpcode::G_ADD:
case TargetOpcode::G_AND:
case TargetOpcode::G_MUL:
case TargetOpcode::G_OR:
case TargetOpcode::G_XOR:
case TargetOpcode::G_SUB:
// Perform operation at larger width (any extension is fine here, high bits
// don't affect the result) and then truncate the result back to the
// original type.
widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_ANYEXT);
widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_ANYEXT);
widenScalarDst(MI, WideTy);
MIRBuilder.recordInsertion(&MI);
return Legalized;
case TargetOpcode::G_SHL:
widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_ANYEXT);
// The "number of bits to shift" operand must preserve its value as an
// unsigned integer:
widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_ZEXT);
widenScalarDst(MI, WideTy);
MIRBuilder.recordInsertion(&MI);
return Legalized;
case TargetOpcode::G_SDIV:
case TargetOpcode::G_SREM:
widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_SEXT);
widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_SEXT);
widenScalarDst(MI, WideTy);
MIRBuilder.recordInsertion(&MI);
return Legalized;
case TargetOpcode::G_ASHR:
widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_SEXT);
// The "number of bits to shift" operand must preserve its value as an
// unsigned integer:
widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_ZEXT);
widenScalarDst(MI, WideTy);
MIRBuilder.recordInsertion(&MI);
return Legalized;
case TargetOpcode::G_UDIV:
case TargetOpcode::G_UREM:
case TargetOpcode::G_LSHR:
widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_ZEXT);
widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_ZEXT);
widenScalarDst(MI, WideTy);
MIRBuilder.recordInsertion(&MI);
return Legalized;
case TargetOpcode::G_SELECT:
if (TypeIdx != 0)
return UnableToLegalize;
// Perform operation at larger width (any extension is fine here, high bits
// don't affect the result) and then truncate the result back to the
// original type.
widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_ANYEXT);
widenScalarSrc(MI, WideTy, 3, TargetOpcode::G_ANYEXT);
widenScalarDst(MI, WideTy);
MIRBuilder.recordInsertion(&MI);
return Legalized;
case TargetOpcode::G_FPTOSI:
case TargetOpcode::G_FPTOUI:
if (TypeIdx != 0)
return UnableToLegalize;
widenScalarDst(MI, WideTy);
MIRBuilder.recordInsertion(&MI);
return Legalized;
case TargetOpcode::G_SITOFP:
if (TypeIdx != 1)
return UnableToLegalize;
widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_SEXT);
MIRBuilder.recordInsertion(&MI);
return Legalized;
case TargetOpcode::G_UITOFP:
if (TypeIdx != 1)
return UnableToLegalize;
widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_ZEXT);
MIRBuilder.recordInsertion(&MI);
return Legalized;
case TargetOpcode::G_INSERT:
if (TypeIdx != 0)
return UnableToLegalize;
widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_ANYEXT);
widenScalarDst(MI, WideTy);
MIRBuilder.recordInsertion(&MI);
return Legalized;
case TargetOpcode::G_LOAD:
// For some types like i24, we might try to widen to i32. To properly handle
// this we should be using a dedicated extending load, until then avoid
// trying to legalize.
if (alignTo(MRI.getType(MI.getOperand(0).getReg()).getSizeInBits(), 8) !=
WideTy.getSizeInBits())
return UnableToLegalize;
LLVM_FALLTHROUGH;
case TargetOpcode::G_SEXTLOAD:
case TargetOpcode::G_ZEXTLOAD:
widenScalarDst(MI, WideTy);
MIRBuilder.recordInsertion(&MI);
return Legalized;
case TargetOpcode::G_STORE: {
if (MRI.getType(MI.getOperand(0).getReg()) != LLT::scalar(1) ||
WideTy != LLT::scalar(8))
return UnableToLegalize;
widenScalarSrc(MI, WideTy, 0, TargetOpcode::G_ZEXT);
MIRBuilder.recordInsertion(&MI);
return Legalized;
}
case TargetOpcode::G_CONSTANT: {
MachineOperand &SrcMO = MI.getOperand(1);
LLVMContext &Ctx = MIRBuilder.getMF().getFunction().getContext();
const APInt &Val = SrcMO.getCImm()->getValue().sext(WideTy.getSizeInBits());
SrcMO.setCImm(ConstantInt::get(Ctx, Val));
widenScalarDst(MI, WideTy);
MIRBuilder.recordInsertion(&MI);
return Legalized;
}
case TargetOpcode::G_FCONSTANT: {
MachineOperand &SrcMO = MI.getOperand(1);
LLVMContext &Ctx = MIRBuilder.getMF().getFunction().getContext();
APFloat Val = SrcMO.getFPImm()->getValueAPF();
bool LosesInfo;
switch (WideTy.getSizeInBits()) {
case 32:
Val.convert(APFloat::IEEEsingle(), APFloat::rmTowardZero, &LosesInfo);
break;
case 64:
Val.convert(APFloat::IEEEdouble(), APFloat::rmTowardZero, &LosesInfo);
break;
default:
llvm_unreachable("Unhandled fp widen type");
}
SrcMO.setFPImm(ConstantFP::get(Ctx, Val));
widenScalarDst(MI, WideTy, 0, TargetOpcode::G_FPTRUNC);
MIRBuilder.recordInsertion(&MI);
return Legalized;
}
case TargetOpcode::G_BRCOND:
widenScalarSrc(MI, WideTy, 0, TargetOpcode::G_ANYEXT);
MIRBuilder.recordInsertion(&MI);
return Legalized;
case TargetOpcode::G_FCMP:
if (TypeIdx == 0)
widenScalarDst(MI, WideTy);
else {
widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_FPEXT);
widenScalarSrc(MI, WideTy, 3, TargetOpcode::G_FPEXT);
}
MIRBuilder.recordInsertion(&MI);
return Legalized;
case TargetOpcode::G_ICMP:
if (TypeIdx == 0)
widenScalarDst(MI, WideTy);
else {
unsigned ExtOpcode = CmpInst::isSigned(static_cast<CmpInst::Predicate>(
MI.getOperand(1).getPredicate()))
? TargetOpcode::G_SEXT
: TargetOpcode::G_ZEXT;
widenScalarSrc(MI, WideTy, 2, ExtOpcode);
widenScalarSrc(MI, WideTy, 3, ExtOpcode);
}
MIRBuilder.recordInsertion(&MI);
return Legalized;
case TargetOpcode::G_GEP:
assert(TypeIdx == 1 && "unable to legalize pointer of GEP");
widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_SEXT);
MIRBuilder.recordInsertion(&MI);
return Legalized;
case TargetOpcode::G_PHI: {
assert(TypeIdx == 0 && "Expecting only Idx 0");
for (unsigned I = 1; I < MI.getNumOperands(); I += 2) {
MachineBasicBlock &OpMBB = *MI.getOperand(I + 1).getMBB();
MIRBuilder.setInsertPt(OpMBB, OpMBB.getFirstTerminator());
widenScalarSrc(MI, WideTy, I, TargetOpcode::G_ANYEXT);
}
MachineBasicBlock &MBB = *MI.getParent();
MIRBuilder.setInsertPt(MBB, --MBB.getFirstNonPHI());
widenScalarDst(MI, WideTy);
MIRBuilder.recordInsertion(&MI);
return Legalized;
}
}
}
LegalizerHelper::LegalizeResult
LegalizerHelper::lower(MachineInstr &MI, unsigned TypeIdx, LLT Ty) {
using namespace TargetOpcode;
MIRBuilder.setInstr(MI);
switch(MI.getOpcode()) {
default:
return UnableToLegalize;
case TargetOpcode::G_SREM:
case TargetOpcode::G_UREM: {
unsigned QuotReg = MRI.createGenericVirtualRegister(Ty);
MIRBuilder.buildInstr(MI.getOpcode() == G_SREM ? G_SDIV : G_UDIV)
.addDef(QuotReg)
.addUse(MI.getOperand(1).getReg())
.addUse(MI.getOperand(2).getReg());
unsigned ProdReg = MRI.createGenericVirtualRegister(Ty);
MIRBuilder.buildMul(ProdReg, QuotReg, MI.getOperand(2).getReg());
MIRBuilder.buildSub(MI.getOperand(0).getReg(), MI.getOperand(1).getReg(),
ProdReg);
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_SMULO:
case TargetOpcode::G_UMULO: {
// Generate G_UMULH/G_SMULH to check for overflow and a normal G_MUL for the
// result.
unsigned Res = MI.getOperand(0).getReg();
unsigned Overflow = MI.getOperand(1).getReg();
unsigned LHS = MI.getOperand(2).getReg();
unsigned RHS = MI.getOperand(3).getReg();
MIRBuilder.buildMul(Res, LHS, RHS);
unsigned Opcode = MI.getOpcode() == TargetOpcode::G_SMULO
? TargetOpcode::G_SMULH
: TargetOpcode::G_UMULH;
unsigned HiPart = MRI.createGenericVirtualRegister(Ty);
MIRBuilder.buildInstr(Opcode)
.addDef(HiPart)
.addUse(LHS)
.addUse(RHS);
unsigned Zero = MRI.createGenericVirtualRegister(Ty);
MIRBuilder.buildConstant(Zero, 0);
// For *signed* multiply, overflow is detected by checking:
// (hi != (lo >> bitwidth-1))
if (Opcode == TargetOpcode::G_SMULH) {
unsigned Shifted = MRI.createGenericVirtualRegister(Ty);
unsigned ShiftAmt = MRI.createGenericVirtualRegister(Ty);
MIRBuilder.buildConstant(ShiftAmt, Ty.getSizeInBits() - 1);
MIRBuilder.buildInstr(TargetOpcode::G_ASHR)
.addDef(Shifted)
.addUse(Res)
.addUse(ShiftAmt);
MIRBuilder.buildICmp(CmpInst::ICMP_NE, Overflow, HiPart, Shifted);
} else {
MIRBuilder.buildICmp(CmpInst::ICMP_NE, Overflow, HiPart, Zero);
}
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_FNEG: {
// TODO: Handle vector types once we are able to
// represent them.
if (Ty.isVector())
return UnableToLegalize;
unsigned Res = MI.getOperand(0).getReg();
Type *ZeroTy;
LLVMContext &Ctx = MIRBuilder.getMF().getFunction().getContext();
switch (Ty.getSizeInBits()) {
case 16:
ZeroTy = Type::getHalfTy(Ctx);
break;
case 32:
ZeroTy = Type::getFloatTy(Ctx);
break;
case 64:
ZeroTy = Type::getDoubleTy(Ctx);
break;
case 128:
ZeroTy = Type::getFP128Ty(Ctx);
break;
default:
llvm_unreachable("unexpected floating-point type");
}
ConstantFP &ZeroForNegation =
*cast<ConstantFP>(ConstantFP::getZeroValueForNegation(ZeroTy));
auto Zero = MIRBuilder.buildFConstant(Ty, ZeroForNegation);
MIRBuilder.buildInstr(TargetOpcode::G_FSUB)
.addDef(Res)
.addUse(Zero->getOperand(0).getReg())
.addUse(MI.getOperand(1).getReg());
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_FSUB: {
// Lower (G_FSUB LHS, RHS) to (G_FADD LHS, (G_FNEG RHS)).
// First, check if G_FNEG is marked as Lower. If so, we may
// end up with an infinite loop as G_FSUB is used to legalize G_FNEG.
if (LI.getAction({G_FNEG, {Ty}}).Action == Lower)
return UnableToLegalize;
unsigned Res = MI.getOperand(0).getReg();
unsigned LHS = MI.getOperand(1).getReg();
unsigned RHS = MI.getOperand(2).getReg();
unsigned Neg = MRI.createGenericVirtualRegister(Ty);
MIRBuilder.buildInstr(TargetOpcode::G_FNEG).addDef(Neg).addUse(RHS);
MIRBuilder.buildInstr(TargetOpcode::G_FADD)
.addDef(Res)
.addUse(LHS)
.addUse(Neg);
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_ATOMIC_CMPXCHG_WITH_SUCCESS: {
unsigned OldValRes = MI.getOperand(0).getReg();
unsigned SuccessRes = MI.getOperand(1).getReg();
unsigned Addr = MI.getOperand(2).getReg();
unsigned CmpVal = MI.getOperand(3).getReg();
unsigned NewVal = MI.getOperand(4).getReg();
MIRBuilder.buildAtomicCmpXchg(OldValRes, Addr, CmpVal, NewVal,
**MI.memoperands_begin());
MIRBuilder.buildICmp(CmpInst::ICMP_EQ, SuccessRes, OldValRes, CmpVal);
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_LOAD:
case TargetOpcode::G_SEXTLOAD:
case TargetOpcode::G_ZEXTLOAD: {
// Lower to a memory-width G_LOAD and a G_SEXT/G_ZEXT/G_ANYEXT
unsigned DstReg = MI.getOperand(0).getReg();
unsigned PtrReg = MI.getOperand(1).getReg();
LLT DstTy = MRI.getType(DstReg);
auto &MMO = **MI.memoperands_begin();
if (DstTy.getSizeInBits() == MMO.getSize() /* in bytes */ * 8) {
// In the case of G_LOAD, this was a non-extending load already and we're
// about to lower to the same instruction.
if (MI.getOpcode() == TargetOpcode::G_LOAD)
return UnableToLegalize;
MIRBuilder.buildLoad(DstReg, PtrReg, MMO);
MI.eraseFromParent();
return Legalized;
}
if (DstTy.isScalar()) {
unsigned TmpReg = MRI.createGenericVirtualRegister(
LLT::scalar(MMO.getSize() /* in bytes */ * 8));
MIRBuilder.buildLoad(TmpReg, PtrReg, MMO);
switch (MI.getOpcode()) {
default:
llvm_unreachable("Unexpected opcode");
case TargetOpcode::G_LOAD:
MIRBuilder.buildAnyExt(DstReg, TmpReg);
break;
case TargetOpcode::G_SEXTLOAD:
MIRBuilder.buildSExt(DstReg, TmpReg);
break;
case TargetOpcode::G_ZEXTLOAD:
MIRBuilder.buildZExt(DstReg, TmpReg);
break;
}
MI.eraseFromParent();
return Legalized;
}
return UnableToLegalize;
}
case TargetOpcode::G_CTLZ_ZERO_UNDEF:
case TargetOpcode::G_CTTZ_ZERO_UNDEF:
case TargetOpcode::G_CTLZ:
case TargetOpcode::G_CTTZ:
case TargetOpcode::G_CTPOP:
return lowerBitCount(MI, TypeIdx, Ty);
}
}
LegalizerHelper::LegalizeResult
LegalizerHelper::fewerElementsVector(MachineInstr &MI, unsigned TypeIdx,
LLT NarrowTy) {
// FIXME: Don't know how to handle secondary types yet.
if (TypeIdx != 0)
return UnableToLegalize;
switch (MI.getOpcode()) {
default:
return UnableToLegalize;
case TargetOpcode::G_ADD: {
unsigned NarrowSize = NarrowTy.getSizeInBits();
unsigned DstReg = MI.getOperand(0).getReg();
unsigned Size = MRI.getType(DstReg).getSizeInBits();
int NumParts = Size / NarrowSize;
// FIXME: Don't know how to handle the situation where the small vectors
// aren't all the same size yet.
if (Size % NarrowSize != 0)
return UnableToLegalize;
MIRBuilder.setInstr(MI);
SmallVector<unsigned, 2> Src1Regs, Src2Regs, DstRegs;
extractParts(MI.getOperand(1).getReg(), NarrowTy, NumParts, Src1Regs);
extractParts(MI.getOperand(2).getReg(), NarrowTy, NumParts, Src2Regs);
for (int i = 0; i < NumParts; ++i) {
unsigned DstReg = MRI.createGenericVirtualRegister(NarrowTy);
MIRBuilder.buildAdd(DstReg, Src1Regs[i], Src2Regs[i]);
DstRegs.push_back(DstReg);
}
MIRBuilder.buildMerge(DstReg, DstRegs);
MI.eraseFromParent();
return Legalized;
}
}
}
LegalizerHelper::LegalizeResult
LegalizerHelper::lowerBitCount(MachineInstr &MI, unsigned TypeIdx, LLT Ty) {
unsigned Opc = MI.getOpcode();
auto &TII = *MI.getMF()->getSubtarget().getInstrInfo();
auto isLegalOrCustom = [this](const LegalityQuery &Q) {
auto QAction = LI.getAction(Q).Action;
return QAction == Legal || QAction == Custom;
};
switch (Opc) {
default:
return UnableToLegalize;
case TargetOpcode::G_CTLZ_ZERO_UNDEF: {
// This trivially expands to CTLZ.
MI.setDesc(TII.get(TargetOpcode::G_CTLZ));
MIRBuilder.recordInsertion(&MI);
return Legalized;
}
case TargetOpcode::G_CTLZ: {
unsigned SrcReg = MI.getOperand(1).getReg();
unsigned Len = Ty.getSizeInBits();
if (isLegalOrCustom({TargetOpcode::G_CTLZ_ZERO_UNDEF, {Ty}})) {
// If CTLZ_ZERO_UNDEF is legal or custom, emit that and a select with
// zero.
auto MIBCtlzZU =
MIRBuilder.buildInstr(TargetOpcode::G_CTLZ_ZERO_UNDEF, Ty, SrcReg);
auto MIBZero = MIRBuilder.buildConstant(Ty, 0);
auto MIBLen = MIRBuilder.buildConstant(Ty, Len);
auto MIBICmp = MIRBuilder.buildICmp(CmpInst::ICMP_EQ, LLT::scalar(1),
SrcReg, MIBZero);
MIRBuilder.buildSelect(MI.getOperand(0).getReg(), MIBICmp, MIBLen,
MIBCtlzZU);
MI.eraseFromParent();
return Legalized;
}
// for now, we do this:
// NewLen = NextPowerOf2(Len);
// x = x | (x >> 1);
// x = x | (x >> 2);
// ...
// x = x | (x >>16);
// x = x | (x >>32); // for 64-bit input
// Upto NewLen/2
// return Len - popcount(x);
//
// Ref: "Hacker's Delight" by Henry Warren
unsigned Op = SrcReg;
unsigned NewLen = PowerOf2Ceil(Len);
for (unsigned i = 0; (1U << i) <= (NewLen / 2); ++i) {
auto MIBShiftAmt = MIRBuilder.buildConstant(Ty, 1ULL << i);
auto MIBOp = MIRBuilder.buildInstr(
TargetOpcode::G_OR, Ty, Op,
MIRBuilder.buildInstr(TargetOpcode::G_LSHR, Ty, Op, MIBShiftAmt));
Op = MIBOp->getOperand(0).getReg();
}
auto MIBPop = MIRBuilder.buildInstr(TargetOpcode::G_CTPOP, Ty, Op);
MIRBuilder.buildInstr(TargetOpcode::G_SUB, MI.getOperand(0).getReg(),
MIRBuilder.buildConstant(Ty, Len), MIBPop);
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_CTTZ_ZERO_UNDEF: {
// This trivially expands to CTTZ.
MI.setDesc(TII.get(TargetOpcode::G_CTTZ));
MIRBuilder.recordInsertion(&MI);
return Legalized;
}
case TargetOpcode::G_CTTZ: {
unsigned SrcReg = MI.getOperand(1).getReg();
unsigned Len = Ty.getSizeInBits();
if (isLegalOrCustom({TargetOpcode::G_CTTZ_ZERO_UNDEF, {Ty}})) {
// If CTTZ_ZERO_UNDEF is legal or custom, emit that and a select with
// zero.
auto MIBCttzZU =
MIRBuilder.buildInstr(TargetOpcode::G_CTTZ_ZERO_UNDEF, Ty, SrcReg);
auto MIBZero = MIRBuilder.buildConstant(Ty, 0);
auto MIBLen = MIRBuilder.buildConstant(Ty, Len);
auto MIBICmp = MIRBuilder.buildICmp(CmpInst::ICMP_EQ, LLT::scalar(1),
SrcReg, MIBZero);
MIRBuilder.buildSelect(MI.getOperand(0).getReg(), MIBICmp, MIBLen,
MIBCttzZU);
MI.eraseFromParent();
return Legalized;
}
// for now, we use: { return popcount(~x & (x - 1)); }
// unless the target has ctlz but not ctpop, in which case we use:
// { return 32 - nlz(~x & (x-1)); }
// Ref: "Hacker's Delight" by Henry Warren
auto MIBCstNeg1 = MIRBuilder.buildConstant(Ty, -1);
auto MIBNot =
MIRBuilder.buildInstr(TargetOpcode::G_XOR, Ty, SrcReg, MIBCstNeg1);
auto MIBTmp = MIRBuilder.buildInstr(
TargetOpcode::G_AND, Ty, MIBNot,
MIRBuilder.buildInstr(TargetOpcode::G_ADD, Ty, SrcReg, MIBCstNeg1));
if (!isLegalOrCustom({TargetOpcode::G_CTPOP, {Ty}}) &&
isLegalOrCustom({TargetOpcode::G_CTLZ, {Ty}})) {
auto MIBCstLen = MIRBuilder.buildConstant(Ty, Len);
MIRBuilder.buildInstr(
TargetOpcode::G_SUB, MI.getOperand(0).getReg(),
MIBCstLen,
MIRBuilder.buildInstr(TargetOpcode::G_CTLZ, Ty, MIBTmp));
MI.eraseFromParent();
return Legalized;
}
MI.setDesc(TII.get(TargetOpcode::G_CTPOP));
MI.getOperand(1).setReg(MIBTmp->getOperand(0).getReg());
return Legalized;
}
}
}
Reference in New Issue View Git Blame Copy Permalink