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//===- CombinerHelperCasts.cpp---------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements CombinerHelper for G_ANYEXT, G_SEXT, G_TRUNC, and
// G_ZEXT
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/GlobalISel/CombinerHelper.h"
#include "llvm/CodeGen/GlobalISel/LegalizerHelper.h"
#include "llvm/CodeGen/GlobalISel/LegalizerInfo.h"
#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
#include "llvm/CodeGen/GlobalISel/Utils.h"
#include "llvm/CodeGen/LowLevelTypeUtils.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetOpcodes.h"
#include "llvm/Support/Casting.h"
#define DEBUG_TYPE "gi-combiner"
using namespace llvm;
bool CombinerHelper::matchSextOfTrunc(const MachineOperand &MO,
BuildFnTy &MatchInfo) {
GSext *Sext = cast<GSext>(getDefIgnoringCopies(MO.getReg(), MRI));
GTrunc *Trunc = cast<GTrunc>(getDefIgnoringCopies(Sext->getSrcReg(), MRI));
Register Dst = Sext->getReg(0);
Register Src = Trunc->getSrcReg();
LLT DstTy = MRI.getType(Dst);
LLT SrcTy = MRI.getType(Src);
if (DstTy == SrcTy) {
MatchInfo = [=](MachineIRBuilder &B) { B.buildCopy(Dst, Src); };
return true;
}
if (DstTy.getScalarSizeInBits() < SrcTy.getScalarSizeInBits() &&
isLegalOrBeforeLegalizer({TargetOpcode::G_TRUNC, {DstTy, SrcTy}})) {
MatchInfo = [=](MachineIRBuilder &B) {
B.buildTrunc(Dst, Src, MachineInstr::MIFlag::NoSWrap);
};
return true;
}
if (DstTy.getScalarSizeInBits() > SrcTy.getScalarSizeInBits() &&
isLegalOrBeforeLegalizer({TargetOpcode::G_SEXT, {DstTy, SrcTy}})) {
MatchInfo = [=](MachineIRBuilder &B) { B.buildSExt(Dst, Src); };
return true;
}
return false;
}
bool CombinerHelper::matchZextOfTrunc(const MachineOperand &MO,
BuildFnTy &MatchInfo) {
GZext *Zext = cast<GZext>(getDefIgnoringCopies(MO.getReg(), MRI));
GTrunc *Trunc = cast<GTrunc>(getDefIgnoringCopies(Zext->getSrcReg(), MRI));
Register Dst = Zext->getReg(0);
Register Src = Trunc->getSrcReg();
LLT DstTy = MRI.getType(Dst);
LLT SrcTy = MRI.getType(Src);
if (DstTy == SrcTy) {
MatchInfo = [=](MachineIRBuilder &B) { B.buildCopy(Dst, Src); };
return true;
}
if (DstTy.getScalarSizeInBits() < SrcTy.getScalarSizeInBits() &&
isLegalOrBeforeLegalizer({TargetOpcode::G_TRUNC, {DstTy, SrcTy}})) {
MatchInfo = [=](MachineIRBuilder &B) {
B.buildTrunc(Dst, Src, MachineInstr::MIFlag::NoUWrap);
};
return true;
}
if (DstTy.getScalarSizeInBits() > SrcTy.getScalarSizeInBits() &&
isLegalOrBeforeLegalizer({TargetOpcode::G_ZEXT, {DstTy, SrcTy}})) {
MatchInfo = [=](MachineIRBuilder &B) {
B.buildZExt(Dst, Src, MachineInstr::MIFlag::NonNeg);
};
return true;
}
return false;
}
bool CombinerHelper::matchNonNegZext(const MachineOperand &MO,
BuildFnTy &MatchInfo) {
GZext *Zext = cast<GZext>(MRI.getVRegDef(MO.getReg()));
Register Dst = Zext->getReg(0);
Register Src = Zext->getSrcReg();
LLT DstTy = MRI.getType(Dst);
LLT SrcTy = MRI.getType(Src);
const auto &TLI = getTargetLowering();
// Convert zext nneg to sext if sext is the preferred form for the target.
if (isLegalOrBeforeLegalizer({TargetOpcode::G_SEXT, {DstTy, SrcTy}}) &&
TLI.isSExtCheaperThanZExt(getMVTForLLT(SrcTy), getMVTForLLT(DstTy))) {
MatchInfo = [=](MachineIRBuilder &B) { B.buildSExt(Dst, Src); };
return true;
}
return false;
}
bool CombinerHelper::matchTruncateOfExt(const MachineInstr &Root,
const MachineInstr &ExtMI,
BuildFnTy &MatchInfo) {
const GTrunc *Trunc = cast<GTrunc>(&Root);
const GExtOp *Ext = cast<GExtOp>(&ExtMI);
if (!MRI.hasOneNonDBGUse(Ext->getReg(0)))
return false;
Register Dst = Trunc->getReg(0);
Register Src = Ext->getSrcReg();
LLT DstTy = MRI.getType(Dst);
LLT SrcTy = MRI.getType(Src);
if (SrcTy == DstTy) {
// The source and the destination are equally sized. We need to copy.
MatchInfo = [=](MachineIRBuilder &B) { B.buildCopy(Dst, Src); };
return true;
}
if (SrcTy.getScalarSizeInBits() < DstTy.getScalarSizeInBits()) {
// If the source is smaller than the destination, we need to extend.
if (!isLegalOrBeforeLegalizer({Ext->getOpcode(), {DstTy, SrcTy}}))
return false;
MatchInfo = [=](MachineIRBuilder &B) {
B.buildInstr(Ext->getOpcode(), {Dst}, {Src});
};
return true;
}
if (SrcTy.getScalarSizeInBits() > DstTy.getScalarSizeInBits()) {
// If the source is larger than the destination, then we need to truncate.
if (!isLegalOrBeforeLegalizer({TargetOpcode::G_TRUNC, {DstTy, SrcTy}}))
return false;
MatchInfo = [=](MachineIRBuilder &B) { B.buildTrunc(Dst, Src); };
return true;
}
return false;
}
bool CombinerHelper::isCastFree(unsigned Opcode, LLT ToTy, LLT FromTy) const {
const TargetLowering &TLI = getTargetLowering();
const DataLayout &DL = getDataLayout();
LLVMContext &Ctx = getContext();
switch (Opcode) {
case TargetOpcode::G_ANYEXT:
case TargetOpcode::G_ZEXT:
return TLI.isZExtFree(FromTy, ToTy, DL, Ctx);
case TargetOpcode::G_TRUNC:
return TLI.isTruncateFree(FromTy, ToTy, DL, Ctx);
default:
return false;
}
}
bool CombinerHelper::matchCastOfSelect(const MachineInstr &CastMI,
const MachineInstr &SelectMI,
BuildFnTy &MatchInfo) {
const GExtOrTruncOp *Cast = cast<GExtOrTruncOp>(&CastMI);
const GSelect *Select = cast<GSelect>(&SelectMI);
if (!MRI.hasOneNonDBGUse(Select->getReg(0)))
return false;
Register Dst = Cast->getReg(0);
LLT DstTy = MRI.getType(Dst);
LLT CondTy = MRI.getType(Select->getCondReg());
Register TrueReg = Select->getTrueReg();
Register FalseReg = Select->getFalseReg();
LLT SrcTy = MRI.getType(TrueReg);
Register Cond = Select->getCondReg();
if (!isLegalOrBeforeLegalizer({TargetOpcode::G_SELECT, {DstTy, CondTy}}))
return false;
if (!isCastFree(Cast->getOpcode(), DstTy, SrcTy))
return false;
MatchInfo = [=](MachineIRBuilder &B) {
auto True = B.buildInstr(Cast->getOpcode(), {DstTy}, {TrueReg});
auto False = B.buildInstr(Cast->getOpcode(), {DstTy}, {FalseReg});
B.buildSelect(Dst, Cond, True, False);
};
return true;
}
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