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//===-- 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::legalizeInstr(
MachineInstr &MI, const MachineLegalizer &Legalizer) {
auto Action = Legalizer.getAction(MI);
switch (Action.first) {
case MachineLegalizer::Legal:
return AlreadyLegal;
case MachineLegalizer::NarrowScalar:
return narrowScalar(MI, Action.second);
case MachineLegalizer::WidenScalar:
return widenScalar(MI, Action.second);
case MachineLegalizer::FewerElements:
return fewerElementsVector(MI, Action.second);
default:
return UnableToLegalize;
}
}
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, LLT NarrowTy) {
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, LLT WideTy) {
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 WideSize = WideTy.getSizeInBits();
MIRBuilder.setInstr(MI);
unsigned Src1Ext = MRI.createGenericVirtualRegister(WideSize);
unsigned Src2Ext = MRI.createGenericVirtualRegister(WideSize);
MIRBuilder.buildAnyExtend(WideTy, Src1Ext, MI.getOperand(1).getReg());
MIRBuilder.buildAnyExtend(WideTy, Src2Ext, MI.getOperand(2).getReg());
unsigned DstExt = MRI.createGenericVirtualRegister(WideSize);
MIRBuilder.buildInstr(MI.getOpcode(), WideTy)
.addDef(DstExt).addUse(Src1Ext).addUse(Src2Ext);
MIRBuilder.buildTrunc(MI.getType(), MI.getOperand(0).getReg(), DstExt);
MI.eraseFromParent();
return Legalized;
}
}
}
MachineLegalizeHelper::LegalizeResult
MachineLegalizeHelper::fewerElementsVector(MachineInstr &MI, LLT NarrowTy) {
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;
}
}
}
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