llvm-project/llvm/lib/CodeGen/GlobalISel/MachineLegalizeHelper.cpp

327 lines
12 KiB
C++

//===-- llvm/CodeGen/GlobalISel/MachineLegalizeHelper.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 MachineLegalizeHelper class to legalize
/// individual instructions and the LegalizeMachineIR wrapper pass for the
/// primary legalization.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/GlobalISel/MachineLegalizeHelper.h"
#include "llvm/CodeGen/GlobalISel/MachineLegalizer.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetSubtargetInfo.h"
#include <sstream>
#define DEBUG_TYPE "legalize-mir"
using namespace llvm;
MachineLegalizeHelper::MachineLegalizeHelper(MachineFunction &MF)
: MRI(MF.getRegInfo()) {
MIRBuilder.setMF(MF);
}
MachineLegalizeHelper::LegalizeResult
MachineLegalizeHelper::legalizeInstrStep(MachineInstr &MI,
const MachineLegalizer &Legalizer) {
auto Action = Legalizer.getAction(MI);
switch (std::get<0>(Action)) {
case MachineLegalizer::Legal:
return AlreadyLegal;
case MachineLegalizer::NarrowScalar:
return narrowScalar(MI, std::get<1>(Action), std::get<2>(Action));
case MachineLegalizer::WidenScalar:
return widenScalar(MI, std::get<1>(Action), std::get<2>(Action));
case MachineLegalizer::Lower:
return lower(MI, std::get<1>(Action), std::get<2>(Action));
case MachineLegalizer::FewerElements:
return fewerElementsVector(MI, std::get<1>(Action), std::get<2>(Action));
default:
return UnableToLegalize;
}
}
MachineLegalizeHelper::LegalizeResult
MachineLegalizeHelper::legalizeInstr(MachineInstr &MI,
const MachineLegalizer &Legalizer) {
std::queue<MachineInstr *> WorkList;
MIRBuilder.recordInsertions([&](MachineInstr *MI) { WorkList.push(MI); });
WorkList.push(&MI);
bool Changed = false;
LegalizeResult Res;
do {
Res = legalizeInstrStep(*WorkList.front(), Legalizer);
if (Res == UnableToLegalize) {
MIRBuilder.stopRecordingInsertions();
return UnableToLegalize;
}
Changed |= Res == Legalized;
WorkList.pop();
} while (!WorkList.empty());
MIRBuilder.stopRecordingInsertions();
return Changed ? Legalized : AlreadyLegal;
}
void MachineLegalizeHelper::extractParts(unsigned Reg, LLT Ty, int NumParts,
SmallVectorImpl<unsigned> &VRegs) {
unsigned Size = Ty.getSizeInBits();
SmallVector<uint64_t, 4> Indexes;
SmallVector<LLT, 4> ResTys;
for (int i = 0; i < NumParts; ++i) {
VRegs.push_back(MRI.createGenericVirtualRegister(Size));
Indexes.push_back(i * Size);
ResTys.push_back(Ty);
}
MIRBuilder.buildExtract(ResTys, VRegs, Indexes,
LLT::scalar(Ty.getSizeInBits() * NumParts), Reg);
}
MachineLegalizeHelper::LegalizeResult
MachineLegalizeHelper::narrowScalar(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: {
// Expand in terms of carry-setting/consuming G_ADDE instructions.
unsigned NarrowSize = NarrowTy.getSizeInBits();
int NumParts = MI.getType().getSizeInBits() / NarrowSize;
MIRBuilder.setInstr(MI);
SmallVector<unsigned, 2> Src1Regs, Src2Regs, DstRegs, Indexes;
extractParts(MI.getOperand(1).getReg(), NarrowTy, NumParts, Src1Regs);
extractParts(MI.getOperand(2).getReg(), NarrowTy, NumParts, Src2Regs);
unsigned CarryIn = MRI.createGenericVirtualRegister(1);
MIRBuilder.buildConstant(LLT::scalar(1), CarryIn, 0);
SmallVector<LLT, 2> DstTys;
for (int i = 0; i < NumParts; ++i) {
unsigned DstReg = MRI.createGenericVirtualRegister(NarrowSize);
unsigned CarryOut = MRI.createGenericVirtualRegister(1);
MIRBuilder.buildUAdde(NarrowTy, DstReg, CarryOut, Src1Regs[i],
Src2Regs[i], CarryIn);
DstTys.push_back(NarrowTy);
DstRegs.push_back(DstReg);
Indexes.push_back(i * NarrowSize);
CarryIn = CarryOut;
}
MIRBuilder.buildSequence(MI.getType(), MI.getOperand(0).getReg(), DstTys,
DstRegs, Indexes);
MI.eraseFromParent();
return Legalized;
}
}
}
MachineLegalizeHelper::LegalizeResult
MachineLegalizeHelper::widenScalar(MachineInstr &MI, unsigned TypeIdx,
LLT WideTy) {
LLT Ty = MI.getType();
unsigned WideSize = WideTy.getSizeInBits();
MIRBuilder.setInstr(MI);
switch (MI.getOpcode()) {
default:
return UnableToLegalize;
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.
unsigned Src1Ext = MRI.createGenericVirtualRegister(WideSize);
unsigned Src2Ext = MRI.createGenericVirtualRegister(WideSize);
MIRBuilder.buildAnyExt({WideTy, Ty}, Src1Ext, MI.getOperand(1).getReg());
MIRBuilder.buildAnyExt({WideTy, Ty}, Src2Ext, MI.getOperand(2).getReg());
unsigned DstExt = MRI.createGenericVirtualRegister(WideSize);
MIRBuilder.buildInstr(MI.getOpcode(), WideTy)
.addDef(DstExt).addUse(Src1Ext).addUse(Src2Ext);
MIRBuilder.buildTrunc({Ty, WideTy}, MI.getOperand(0).getReg(), DstExt);
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_SDIV:
case TargetOpcode::G_UDIV: {
unsigned ExtOp = MI.getOpcode() == TargetOpcode::G_SDIV
? TargetOpcode::G_SEXT
: TargetOpcode::G_ZEXT;
unsigned LHSExt = MRI.createGenericVirtualRegister(WideSize);
MIRBuilder.buildInstr(ExtOp, {WideTy, MI.getType()})
.addDef(LHSExt)
.addUse(MI.getOperand(1).getReg());
unsigned RHSExt = MRI.createGenericVirtualRegister(WideSize);
MIRBuilder.buildInstr(ExtOp, {WideTy, MI.getType()})
.addDef(RHSExt)
.addUse(MI.getOperand(2).getReg());
unsigned ResExt = MRI.createGenericVirtualRegister(WideSize);
MIRBuilder.buildInstr(MI.getOpcode(), WideTy)
.addDef(ResExt)
.addUse(LHSExt)
.addUse(RHSExt);
MIRBuilder.buildTrunc({MI.getType(), WideTy}, MI.getOperand(0).getReg(),
ResExt);
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_LOAD: {
assert(alignTo(Ty.getSizeInBits(), 8) == WideSize &&
"illegal to increase number of bytes loaded");
unsigned DstExt = MRI.createGenericVirtualRegister(WideSize);
MIRBuilder.buildLoad(WideTy, MI.getType(1), DstExt,
MI.getOperand(1).getReg(), **MI.memoperands_begin());
MIRBuilder.buildTrunc({Ty, WideTy}, MI.getOperand(0).getReg(), DstExt);
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_STORE: {
assert(alignTo(Ty.getSizeInBits(), 8) == WideSize &&
"illegal to increase number of bytes modified by a store");
unsigned SrcExt = MRI.createGenericVirtualRegister(WideSize);
MIRBuilder.buildAnyExt({WideTy, Ty}, SrcExt, MI.getOperand(0).getReg());
MIRBuilder.buildStore(WideTy, MI.getType(1), SrcExt,
MI.getOperand(1).getReg(), **MI.memoperands_begin());
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_CONSTANT: {
unsigned DstExt = MRI.createGenericVirtualRegister(WideSize);
MIRBuilder.buildConstant(WideTy, DstExt, MI.getOperand(1).getImm());
MIRBuilder.buildTrunc({Ty, WideTy}, MI.getOperand(0).getReg(), DstExt);
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_FCONSTANT: {
unsigned DstExt = MRI.createGenericVirtualRegister(WideSize);
MIRBuilder.buildFConstant(WideTy, DstExt, *MI.getOperand(1).getFPImm());
MIRBuilder.buildFPTrunc({Ty, WideTy}, MI.getOperand(0).getReg(), DstExt);
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_BRCOND: {
unsigned TstExt = MRI.createGenericVirtualRegister(WideSize);
MIRBuilder.buildAnyExt({WideTy, Ty}, TstExt, MI.getOperand(0).getReg());
MIRBuilder.buildBrCond(WideTy, TstExt, *MI.getOperand(1).getMBB());
MI.eraseFromParent();
return Legalized;
}
case TargetOpcode::G_ICMP: {
assert(TypeIdx == 1 && "unable to legalize predicate");
bool IsSigned = CmpInst::isSigned(
static_cast<CmpInst::Predicate>(MI.getOperand(1).getPredicate()));
unsigned Op0Ext = MRI.createGenericVirtualRegister(WideSize);
unsigned Op1Ext = MRI.createGenericVirtualRegister(WideSize);
if (IsSigned) {
MIRBuilder.buildSExt({WideTy, MI.getType(1)}, Op0Ext,
MI.getOperand(2).getReg());
MIRBuilder.buildSExt({WideTy, MI.getType(1)}, Op1Ext,
MI.getOperand(3).getReg());
} else {
MIRBuilder.buildZExt({WideTy, MI.getType(1)}, Op0Ext,
MI.getOperand(2).getReg());
MIRBuilder.buildZExt({WideTy, MI.getType(1)}, Op1Ext,
MI.getOperand(3).getReg());
}
MIRBuilder.buildICmp(
{MI.getType(0), WideTy},
static_cast<CmpInst::Predicate>(MI.getOperand(1).getPredicate()),
MI.getOperand(0).getReg(), Op0Ext, Op1Ext);
MI.eraseFromParent();
return Legalized;
}
}
}
MachineLegalizeHelper::LegalizeResult
MachineLegalizeHelper::lower(MachineInstr &MI, unsigned TypeIdx, LLT Ty) {
using namespace TargetOpcode;
unsigned Size = Ty.getSizeInBits();
MIRBuilder.setInstr(MI);
switch(MI.getOpcode()) {
default:
return UnableToLegalize;
case TargetOpcode::G_SREM:
case TargetOpcode::G_UREM: {
unsigned QuotReg = MRI.createGenericVirtualRegister(Size);
MIRBuilder.buildInstr(MI.getOpcode() == G_SREM ? G_SDIV : G_UDIV, Ty)
.addDef(QuotReg)
.addUse(MI.getOperand(1).getReg())
.addUse(MI.getOperand(2).getReg());
unsigned ProdReg = MRI.createGenericVirtualRegister(Size);
MIRBuilder.buildMul(Ty, ProdReg, QuotReg, MI.getOperand(2).getReg());
MIRBuilder.buildSub(Ty, MI.getOperand(0).getReg(),
MI.getOperand(1).getReg(), ProdReg);
MI.eraseFromParent();
return Legalized;
}
}
}
MachineLegalizeHelper::LegalizeResult
MachineLegalizeHelper::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();
int NumParts = MI.getType().getSizeInBits() / NarrowSize;
MIRBuilder.setInstr(MI);
SmallVector<unsigned, 2> Src1Regs, Src2Regs, DstRegs, Indexes;
extractParts(MI.getOperand(1).getReg(), NarrowTy, NumParts, Src1Regs);
extractParts(MI.getOperand(2).getReg(), NarrowTy, NumParts, Src2Regs);
SmallVector<LLT, 2> DstTys;
for (int i = 0; i < NumParts; ++i) {
unsigned DstReg = MRI.createGenericVirtualRegister(NarrowSize);
MIRBuilder.buildAdd(NarrowTy, DstReg, Src1Regs[i], Src2Regs[i]);
DstTys.push_back(NarrowTy);
DstRegs.push_back(DstReg);
Indexes.push_back(i * NarrowSize);
}
MIRBuilder.buildSequence(MI.getType(), MI.getOperand(0).getReg(), DstTys,
DstRegs, Indexes);
MI.eraseFromParent();
return Legalized;
}
}
}