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SIFoldOperands.cpp
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SIFoldOperands.cpp
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//===-- SIFoldOperands.cpp - Fold operands --- ----------------------------===//
//
// 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
//
/// \file
//===----------------------------------------------------------------------===//
//
#include "AMDGPU.h"
#include "AMDGPUSubtarget.h"
#include "SIInstrInfo.h"
#include "SIMachineFunctionInfo.h"
#include "MCTargetDesc/AMDGPUMCTargetDesc.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/CodeGen/LiveIntervals.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#define DEBUG_TYPE "si-fold-operands"
using namespace llvm;
namespace {
struct FoldCandidate {
MachineInstr *UseMI;
union {
MachineOperand *OpToFold;
uint64_t ImmToFold;
int FrameIndexToFold;
};
int ShrinkOpcode;
unsigned char UseOpNo;
MachineOperand::MachineOperandType Kind;
bool Commuted;
FoldCandidate(MachineInstr *MI, unsigned OpNo, MachineOperand *FoldOp,
bool Commuted_ = false,
int ShrinkOp = -1) :
UseMI(MI), OpToFold(nullptr), ShrinkOpcode(ShrinkOp), UseOpNo(OpNo),
Kind(FoldOp->getType()),
Commuted(Commuted_) {
if (FoldOp->isImm()) {
ImmToFold = FoldOp->getImm();
} else if (FoldOp->isFI()) {
FrameIndexToFold = FoldOp->getIndex();
} else {
assert(FoldOp->isReg() || FoldOp->isGlobal());
OpToFold = FoldOp;
}
}
bool isFI() const {
return Kind == MachineOperand::MO_FrameIndex;
}
bool isImm() const {
return Kind == MachineOperand::MO_Immediate;
}
bool isReg() const {
return Kind == MachineOperand::MO_Register;
}
bool isGlobal() const { return Kind == MachineOperand::MO_GlobalAddress; }
bool isCommuted() const {
return Commuted;
}
bool needsShrink() const {
return ShrinkOpcode != -1;
}
int getShrinkOpcode() const {
return ShrinkOpcode;
}
};
class SIFoldOperands : public MachineFunctionPass {
public:
static char ID;
MachineRegisterInfo *MRI;
const SIInstrInfo *TII;
const SIRegisterInfo *TRI;
const GCNSubtarget *ST;
const SIMachineFunctionInfo *MFI;
void foldOperand(MachineOperand &OpToFold,
MachineInstr *UseMI,
int UseOpIdx,
SmallVectorImpl<FoldCandidate> &FoldList,
SmallVectorImpl<MachineInstr *> &CopiesToReplace) const;
void foldInstOperand(MachineInstr &MI, MachineOperand &OpToFold) const;
const MachineOperand *isClamp(const MachineInstr &MI) const;
bool tryFoldClamp(MachineInstr &MI);
std::pair<const MachineOperand *, int> isOMod(const MachineInstr &MI) const;
bool tryFoldOMod(MachineInstr &MI);
public:
SIFoldOperands() : MachineFunctionPass(ID) {
initializeSIFoldOperandsPass(*PassRegistry::getPassRegistry());
}
bool runOnMachineFunction(MachineFunction &MF) override;
StringRef getPassName() const override { return "SI Fold Operands"; }
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
MachineFunctionPass::getAnalysisUsage(AU);
}
};
} // End anonymous namespace.
INITIALIZE_PASS(SIFoldOperands, DEBUG_TYPE,
"SI Fold Operands", false, false)
char SIFoldOperands::ID = 0;
char &llvm::SIFoldOperandsID = SIFoldOperands::ID;
// Wrapper around isInlineConstant that understands special cases when
// instruction types are replaced during operand folding.
static bool isInlineConstantIfFolded(const SIInstrInfo *TII,
const MachineInstr &UseMI,
unsigned OpNo,
const MachineOperand &OpToFold) {
if (TII->isInlineConstant(UseMI, OpNo, OpToFold))
return true;
unsigned Opc = UseMI.getOpcode();
switch (Opc) {
case AMDGPU::V_MAC_F32_e64:
case AMDGPU::V_MAC_F16_e64:
case AMDGPU::V_FMAC_F32_e64:
case AMDGPU::V_FMAC_F16_e64: {
// Special case for mac. Since this is replaced with mad when folded into
// src2, we need to check the legality for the final instruction.
int Src2Idx = AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::src2);
if (static_cast<int>(OpNo) == Src2Idx) {
bool IsFMA = Opc == AMDGPU::V_FMAC_F32_e64 ||
Opc == AMDGPU::V_FMAC_F16_e64;
bool IsF32 = Opc == AMDGPU::V_MAC_F32_e64 ||
Opc == AMDGPU::V_FMAC_F32_e64;
unsigned Opc = IsFMA ?
(IsF32 ? AMDGPU::V_FMA_F32 : AMDGPU::V_FMA_F16_gfx9) :
(IsF32 ? AMDGPU::V_MAD_F32 : AMDGPU::V_MAD_F16);
const MCInstrDesc &MadDesc = TII->get(Opc);
return TII->isInlineConstant(OpToFold, MadDesc.OpInfo[OpNo].OperandType);
}
return false;
}
default:
return false;
}
}
// TODO: Add heuristic that the frame index might not fit in the addressing mode
// immediate offset to avoid materializing in loops.
static bool frameIndexMayFold(const SIInstrInfo *TII,
const MachineInstr &UseMI,
int OpNo,
const MachineOperand &OpToFold) {
return OpToFold.isFI() &&
(TII->isMUBUF(UseMI) || TII->isFLATScratch(UseMI)) &&
OpNo == AMDGPU::getNamedOperandIdx(UseMI.getOpcode(), AMDGPU::OpName::vaddr);
}
FunctionPass *llvm::createSIFoldOperandsPass() {
return new SIFoldOperands();
}
static bool updateOperand(FoldCandidate &Fold,
const SIInstrInfo &TII,
const TargetRegisterInfo &TRI,
const GCNSubtarget &ST) {
MachineInstr *MI = Fold.UseMI;
MachineOperand &Old = MI->getOperand(Fold.UseOpNo);
assert(Old.isReg());
if (Fold.isImm()) {
if (MI->getDesc().TSFlags & SIInstrFlags::IsPacked &&
!(MI->getDesc().TSFlags & SIInstrFlags::IsMAI) &&
AMDGPU::isInlinableLiteralV216(static_cast<uint16_t>(Fold.ImmToFold),
ST.hasInv2PiInlineImm())) {
// Set op_sel/op_sel_hi on this operand or bail out if op_sel is
// already set.
unsigned Opcode = MI->getOpcode();
int OpNo = MI->getOperandNo(&Old);
int ModIdx = -1;
if (OpNo == AMDGPU::getNamedOperandIdx(Opcode, AMDGPU::OpName::src0))
ModIdx = AMDGPU::OpName::src0_modifiers;
else if (OpNo == AMDGPU::getNamedOperandIdx(Opcode, AMDGPU::OpName::src1))
ModIdx = AMDGPU::OpName::src1_modifiers;
else if (OpNo == AMDGPU::getNamedOperandIdx(Opcode, AMDGPU::OpName::src2))
ModIdx = AMDGPU::OpName::src2_modifiers;
assert(ModIdx != -1);
ModIdx = AMDGPU::getNamedOperandIdx(Opcode, ModIdx);
MachineOperand &Mod = MI->getOperand(ModIdx);
unsigned Val = Mod.getImm();
if ((Val & SISrcMods::OP_SEL_0) || !(Val & SISrcMods::OP_SEL_1))
return false;
// Only apply the following transformation if that operand requries
// a packed immediate.
switch (TII.get(Opcode).OpInfo[OpNo].OperandType) {
case AMDGPU::OPERAND_REG_IMM_V2FP16:
case AMDGPU::OPERAND_REG_IMM_V2INT16:
case AMDGPU::OPERAND_REG_INLINE_C_V2FP16:
case AMDGPU::OPERAND_REG_INLINE_C_V2INT16:
// If upper part is all zero we do not need op_sel_hi.
if (!isUInt<16>(Fold.ImmToFold)) {
if (!(Fold.ImmToFold & 0xffff)) {
Mod.setImm(Mod.getImm() | SISrcMods::OP_SEL_0);
Mod.setImm(Mod.getImm() & ~SISrcMods::OP_SEL_1);
Old.ChangeToImmediate((Fold.ImmToFold >> 16) & 0xffff);
return true;
}
Mod.setImm(Mod.getImm() & ~SISrcMods::OP_SEL_1);
Old.ChangeToImmediate(Fold.ImmToFold & 0xffff);
return true;
}
break;
default:
break;
}
}
}
if ((Fold.isImm() || Fold.isFI() || Fold.isGlobal()) && Fold.needsShrink()) {
MachineBasicBlock *MBB = MI->getParent();
auto Liveness = MBB->computeRegisterLiveness(&TRI, AMDGPU::VCC, MI, 16);
if (Liveness != MachineBasicBlock::LQR_Dead) {
LLVM_DEBUG(dbgs() << "Not shrinking " << MI << " due to vcc liveness\n");
return false;
}
MachineRegisterInfo &MRI = MBB->getParent()->getRegInfo();
int Op32 = Fold.getShrinkOpcode();
MachineOperand &Dst0 = MI->getOperand(0);
MachineOperand &Dst1 = MI->getOperand(1);
assert(Dst0.isDef() && Dst1.isDef());
bool HaveNonDbgCarryUse = !MRI.use_nodbg_empty(Dst1.getReg());
const TargetRegisterClass *Dst0RC = MRI.getRegClass(Dst0.getReg());
Register NewReg0 = MRI.createVirtualRegister(Dst0RC);
MachineInstr *Inst32 = TII.buildShrunkInst(*MI, Op32);
if (HaveNonDbgCarryUse) {
BuildMI(*MBB, MI, MI->getDebugLoc(), TII.get(AMDGPU::COPY), Dst1.getReg())
.addReg(AMDGPU::VCC, RegState::Kill);
}
// Keep the old instruction around to avoid breaking iterators, but
// replace it with a dummy instruction to remove uses.
//
// FIXME: We should not invert how this pass looks at operands to avoid
// this. Should track set of foldable movs instead of looking for uses
// when looking at a use.
Dst0.setReg(NewReg0);
for (unsigned I = MI->getNumOperands() - 1; I > 0; --I)
MI->RemoveOperand(I);
MI->setDesc(TII.get(AMDGPU::IMPLICIT_DEF));
if (Fold.isCommuted())
TII.commuteInstruction(*Inst32, false);
return true;
}
assert(!Fold.needsShrink() && "not handled");
if (Fold.isImm()) {
Old.ChangeToImmediate(Fold.ImmToFold);
return true;
}
if (Fold.isGlobal()) {
Old.ChangeToGA(Fold.OpToFold->getGlobal(), Fold.OpToFold->getOffset(),
Fold.OpToFold->getTargetFlags());
return true;
}
if (Fold.isFI()) {
Old.ChangeToFrameIndex(Fold.FrameIndexToFold);
return true;
}
MachineOperand *New = Fold.OpToFold;
Old.substVirtReg(New->getReg(), New->getSubReg(), TRI);
Old.setIsUndef(New->isUndef());
return true;
}
static bool isUseMIInFoldList(ArrayRef<FoldCandidate> FoldList,
const MachineInstr *MI) {
for (auto Candidate : FoldList) {
if (Candidate.UseMI == MI)
return true;
}
return false;
}
static bool tryAddToFoldList(SmallVectorImpl<FoldCandidate> &FoldList,
MachineInstr *MI, unsigned OpNo,
MachineOperand *OpToFold,
const SIInstrInfo *TII) {
if (!TII->isOperandLegal(*MI, OpNo, OpToFold)) {
// Special case for v_mac_{f16, f32}_e64 if we are trying to fold into src2
unsigned Opc = MI->getOpcode();
if ((Opc == AMDGPU::V_MAC_F32_e64 || Opc == AMDGPU::V_MAC_F16_e64 ||
Opc == AMDGPU::V_FMAC_F32_e64 || Opc == AMDGPU::V_FMAC_F16_e64) &&
(int)OpNo == AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::src2)) {
bool IsFMA = Opc == AMDGPU::V_FMAC_F32_e64 ||
Opc == AMDGPU::V_FMAC_F16_e64;
bool IsF32 = Opc == AMDGPU::V_MAC_F32_e64 ||
Opc == AMDGPU::V_FMAC_F32_e64;
unsigned NewOpc = IsFMA ?
(IsF32 ? AMDGPU::V_FMA_F32 : AMDGPU::V_FMA_F16_gfx9) :
(IsF32 ? AMDGPU::V_MAD_F32 : AMDGPU::V_MAD_F16);
// Check if changing this to a v_mad_{f16, f32} instruction will allow us
// to fold the operand.
MI->setDesc(TII->get(NewOpc));
bool FoldAsMAD = tryAddToFoldList(FoldList, MI, OpNo, OpToFold, TII);
if (FoldAsMAD) {
MI->untieRegOperand(OpNo);
return true;
}
MI->setDesc(TII->get(Opc));
}
// Special case for s_setreg_b32
if (Opc == AMDGPU::S_SETREG_B32 && OpToFold->isImm()) {
MI->setDesc(TII->get(AMDGPU::S_SETREG_IMM32_B32));
FoldList.push_back(FoldCandidate(MI, OpNo, OpToFold));
return true;
}
// If we are already folding into another operand of MI, then
// we can't commute the instruction, otherwise we risk making the
// other fold illegal.
if (isUseMIInFoldList(FoldList, MI))
return false;
unsigned CommuteOpNo = OpNo;
// Operand is not legal, so try to commute the instruction to
// see if this makes it possible to fold.
unsigned CommuteIdx0 = TargetInstrInfo::CommuteAnyOperandIndex;
unsigned CommuteIdx1 = TargetInstrInfo::CommuteAnyOperandIndex;
bool CanCommute = TII->findCommutedOpIndices(*MI, CommuteIdx0, CommuteIdx1);
if (CanCommute) {
if (CommuteIdx0 == OpNo)
CommuteOpNo = CommuteIdx1;
else if (CommuteIdx1 == OpNo)
CommuteOpNo = CommuteIdx0;
}
// One of operands might be an Imm operand, and OpNo may refer to it after
// the call of commuteInstruction() below. Such situations are avoided
// here explicitly as OpNo must be a register operand to be a candidate
// for memory folding.
if (CanCommute && (!MI->getOperand(CommuteIdx0).isReg() ||
!MI->getOperand(CommuteIdx1).isReg()))
return false;
if (!CanCommute ||
!TII->commuteInstruction(*MI, false, CommuteIdx0, CommuteIdx1))
return false;
if (!TII->isOperandLegal(*MI, CommuteOpNo, OpToFold)) {
if ((Opc == AMDGPU::V_ADD_I32_e64 ||
Opc == AMDGPU::V_SUB_I32_e64 ||
Opc == AMDGPU::V_SUBREV_I32_e64) && // FIXME
(OpToFold->isImm() || OpToFold->isFI() || OpToFold->isGlobal())) {
MachineRegisterInfo &MRI = MI->getParent()->getParent()->getRegInfo();
// Verify the other operand is a VGPR, otherwise we would violate the
// constant bus restriction.
unsigned OtherIdx = CommuteOpNo == CommuteIdx0 ? CommuteIdx1 : CommuteIdx0;
MachineOperand &OtherOp = MI->getOperand(OtherIdx);
if (!OtherOp.isReg() ||
!TII->getRegisterInfo().isVGPR(MRI, OtherOp.getReg()))
return false;
assert(MI->getOperand(1).isDef());
// Make sure to get the 32-bit version of the commuted opcode.
unsigned MaybeCommutedOpc = MI->getOpcode();
int Op32 = AMDGPU::getVOPe32(MaybeCommutedOpc);
FoldList.push_back(FoldCandidate(MI, CommuteOpNo, OpToFold, true,
Op32));
return true;
}
TII->commuteInstruction(*MI, false, CommuteIdx0, CommuteIdx1);
return false;
}
FoldList.push_back(FoldCandidate(MI, CommuteOpNo, OpToFold, true));
return true;
}
FoldList.push_back(FoldCandidate(MI, OpNo, OpToFold));
return true;
}
// If the use operand doesn't care about the value, this may be an operand only
// used for register indexing, in which case it is unsafe to fold.
static bool isUseSafeToFold(const SIInstrInfo *TII,
const MachineInstr &MI,
const MachineOperand &UseMO) {
return !UseMO.isUndef() && !TII->isSDWA(MI);
//return !MI.hasRegisterImplicitUseOperand(UseMO.getReg());
}
static bool tryToFoldACImm(const SIInstrInfo *TII,
const MachineOperand &OpToFold,
MachineInstr *UseMI,
unsigned UseOpIdx,
SmallVectorImpl<FoldCandidate> &FoldList) {
const MCInstrDesc &Desc = UseMI->getDesc();
const MCOperandInfo *OpInfo = Desc.OpInfo;
if (!OpInfo || UseOpIdx >= Desc.getNumOperands())
return false;
uint8_t OpTy = OpInfo[UseOpIdx].OperandType;
if (OpTy < AMDGPU::OPERAND_REG_INLINE_AC_FIRST ||
OpTy > AMDGPU::OPERAND_REG_INLINE_AC_LAST)
return false;
if (OpToFold.isImm() && TII->isInlineConstant(OpToFold, OpTy) &&
TII->isOperandLegal(*UseMI, UseOpIdx, &OpToFold)) {
UseMI->getOperand(UseOpIdx).ChangeToImmediate(OpToFold.getImm());
return true;
}
if (!OpToFold.isReg())
return false;
Register UseReg = OpToFold.getReg();
if (!Register::isVirtualRegister(UseReg))
return false;
if (llvm::find_if(FoldList, [UseMI](const FoldCandidate &FC) {
return FC.UseMI == UseMI; }) != FoldList.end())
return false;
MachineRegisterInfo &MRI = UseMI->getParent()->getParent()->getRegInfo();
const MachineInstr *Def = MRI.getUniqueVRegDef(UseReg);
if (!Def || !Def->isRegSequence())
return false;
int64_t Imm;
MachineOperand *Op;
for (unsigned I = 1, E = Def->getNumExplicitOperands(); I < E; I += 2) {
const MachineOperand &Sub = Def->getOperand(I);
if (!Sub.isReg() || Sub.getSubReg())
return false;
MachineInstr *SubDef = MRI.getUniqueVRegDef(Sub.getReg());
while (SubDef && !SubDef->isMoveImmediate() &&
!SubDef->getOperand(1).isImm() && TII->isFoldableCopy(*SubDef))
SubDef = MRI.getUniqueVRegDef(SubDef->getOperand(1).getReg());
if (!SubDef || !SubDef->isMoveImmediate() || !SubDef->getOperand(1).isImm())
return false;
Op = &SubDef->getOperand(1);
auto SubImm = Op->getImm();
if (I == 1) {
if (!TII->isInlineConstant(SubDef->getOperand(1), OpTy))
return false;
Imm = SubImm;
continue;
}
if (Imm != SubImm)
return false; // Can only fold splat constants
}
if (!TII->isOperandLegal(*UseMI, UseOpIdx, Op))
return false;
FoldList.push_back(FoldCandidate(UseMI, UseOpIdx, Op));
return true;
}
void SIFoldOperands::foldOperand(
MachineOperand &OpToFold,
MachineInstr *UseMI,
int UseOpIdx,
SmallVectorImpl<FoldCandidate> &FoldList,
SmallVectorImpl<MachineInstr *> &CopiesToReplace) const {
const MachineOperand &UseOp = UseMI->getOperand(UseOpIdx);
if (!isUseSafeToFold(TII, *UseMI, UseOp))
return;
// FIXME: Fold operands with subregs.
if (UseOp.isReg() && OpToFold.isReg()) {
if (UseOp.isImplicit() || UseOp.getSubReg() != AMDGPU::NoSubRegister)
return;
// Don't fold subregister extracts into tied operands, only if it is a full
// copy since a subregister use tied to a full register def doesn't really
// make sense. e.g. don't fold:
//
// %1 = COPY %0:sub1
// %2<tied3> = V_MAC_{F16, F32} %3, %4, %1<tied0>
//
// into
// %2<tied3> = V_MAC_{F16, F32} %3, %4, %0:sub1<tied0>
if (UseOp.isTied() && OpToFold.getSubReg() != AMDGPU::NoSubRegister)
return;
}
// Special case for REG_SEQUENCE: We can't fold literals into
// REG_SEQUENCE instructions, so we have to fold them into the
// uses of REG_SEQUENCE.
if (UseMI->isRegSequence()) {
Register RegSeqDstReg = UseMI->getOperand(0).getReg();
unsigned RegSeqDstSubReg = UseMI->getOperand(UseOpIdx + 1).getImm();
MachineRegisterInfo::use_iterator Next;
for (MachineRegisterInfo::use_iterator
RSUse = MRI->use_begin(RegSeqDstReg), RSE = MRI->use_end();
RSUse != RSE; RSUse = Next) {
Next = std::next(RSUse);
MachineInstr *RSUseMI = RSUse->getParent();
if (tryToFoldACImm(TII, UseMI->getOperand(0), RSUseMI,
RSUse.getOperandNo(), FoldList))
continue;
if (RSUse->getSubReg() != RegSeqDstSubReg)
continue;
foldOperand(OpToFold, RSUseMI, RSUse.getOperandNo(), FoldList,
CopiesToReplace);
}
return;
}
if (tryToFoldACImm(TII, OpToFold, UseMI, UseOpIdx, FoldList))
return;
if (frameIndexMayFold(TII, *UseMI, UseOpIdx, OpToFold)) {
// Sanity check that this is a stack access.
// FIXME: Should probably use stack pseudos before frame lowering.
MachineOperand *SOff = TII->getNamedOperand(*UseMI, AMDGPU::OpName::soffset);
if (!SOff->isReg() || (SOff->getReg() != MFI->getScratchWaveOffsetReg() &&
SOff->getReg() != MFI->getStackPtrOffsetReg()))
return;
if (TII->getNamedOperand(*UseMI, AMDGPU::OpName::srsrc)->getReg() !=
MFI->getScratchRSrcReg())
return;
// A frame index will resolve to a positive constant, so it should always be
// safe to fold the addressing mode, even pre-GFX9.
UseMI->getOperand(UseOpIdx).ChangeToFrameIndex(OpToFold.getIndex());
SOff->setReg(MFI->getStackPtrOffsetReg());
return;
}
bool FoldingImmLike =
OpToFold.isImm() || OpToFold.isFI() || OpToFold.isGlobal();
if (FoldingImmLike && UseMI->isCopy()) {
Register DestReg = UseMI->getOperand(0).getReg();
// Don't fold into a copy to a physical register. Doing so would interfere
// with the register coalescer's logic which would avoid redundant
// initalizations.
if (DestReg.isPhysical())
return;
const TargetRegisterClass *DestRC = MRI->getRegClass(DestReg);
Register SrcReg = UseMI->getOperand(1).getReg();
if (SrcReg.isVirtual()) { // XXX - This can be an assert?
const TargetRegisterClass * SrcRC = MRI->getRegClass(SrcReg);
if (TRI->isSGPRClass(SrcRC) && TRI->hasVectorRegisters(DestRC)) {
MachineRegisterInfo::use_iterator NextUse;
SmallVector<FoldCandidate, 4> CopyUses;
for (MachineRegisterInfo::use_iterator
Use = MRI->use_begin(DestReg), E = MRI->use_end();
Use != E; Use = NextUse) {
NextUse = std::next(Use);
FoldCandidate FC = FoldCandidate(Use->getParent(),
Use.getOperandNo(), &UseMI->getOperand(1));
CopyUses.push_back(FC);
}
for (auto & F : CopyUses) {
foldOperand(*F.OpToFold, F.UseMI, F.UseOpNo,
FoldList, CopiesToReplace);
}
}
}
if (DestRC == &AMDGPU::AGPR_32RegClass &&
TII->isInlineConstant(OpToFold, AMDGPU::OPERAND_REG_INLINE_C_INT32)) {
UseMI->setDesc(TII->get(AMDGPU::V_ACCVGPR_WRITE_B32));
UseMI->getOperand(1).ChangeToImmediate(OpToFold.getImm());
CopiesToReplace.push_back(UseMI);
return;
}
// In order to fold immediates into copies, we need to change the
// copy to a MOV.
unsigned MovOp = TII->getMovOpcode(DestRC);
if (MovOp == AMDGPU::COPY)
return;
UseMI->setDesc(TII->get(MovOp));
MachineInstr::mop_iterator ImpOpI = UseMI->implicit_operands().begin();
MachineInstr::mop_iterator ImpOpE = UseMI->implicit_operands().end();
while (ImpOpI != ImpOpE) {
MachineInstr::mop_iterator Tmp = ImpOpI;
ImpOpI++;
UseMI->RemoveOperand(UseMI->getOperandNo(Tmp));
}
CopiesToReplace.push_back(UseMI);
} else {
if (UseMI->isCopy() && OpToFold.isReg() &&
Register::isVirtualRegister(UseMI->getOperand(0).getReg()) &&
TRI->isVectorRegister(*MRI, UseMI->getOperand(0).getReg()) &&
TRI->isVectorRegister(*MRI, UseMI->getOperand(1).getReg()) &&
!UseMI->getOperand(1).getSubReg()) {
unsigned Size = TII->getOpSize(*UseMI, 1);
UseMI->getOperand(1).setReg(OpToFold.getReg());
UseMI->getOperand(1).setSubReg(OpToFold.getSubReg());
UseMI->getOperand(1).setIsKill(false);
CopiesToReplace.push_back(UseMI);
OpToFold.setIsKill(false);
if (Size != 4)
return;
if (TRI->isAGPR(*MRI, UseMI->getOperand(0).getReg()) &&
TRI->isVGPR(*MRI, UseMI->getOperand(1).getReg()))
UseMI->setDesc(TII->get(AMDGPU::V_ACCVGPR_WRITE_B32));
else if (TRI->isVGPR(*MRI, UseMI->getOperand(0).getReg()) &&
TRI->isAGPR(*MRI, UseMI->getOperand(1).getReg()))
UseMI->setDesc(TII->get(AMDGPU::V_ACCVGPR_READ_B32));
return;
}
unsigned UseOpc = UseMI->getOpcode();
if (UseOpc == AMDGPU::V_READFIRSTLANE_B32 ||
(UseOpc == AMDGPU::V_READLANE_B32 &&
(int)UseOpIdx ==
AMDGPU::getNamedOperandIdx(UseOpc, AMDGPU::OpName::src0))) {
// %vgpr = V_MOV_B32 imm
// %sgpr = V_READFIRSTLANE_B32 %vgpr
// =>
// %sgpr = S_MOV_B32 imm
if (FoldingImmLike) {
if (execMayBeModifiedBeforeUse(*MRI,
UseMI->getOperand(UseOpIdx).getReg(),
*OpToFold.getParent(),
*UseMI))
return;
UseMI->setDesc(TII->get(AMDGPU::S_MOV_B32));
// FIXME: ChangeToImmediate should clear subreg
UseMI->getOperand(1).setSubReg(0);
if (OpToFold.isImm())
UseMI->getOperand(1).ChangeToImmediate(OpToFold.getImm());
else
UseMI->getOperand(1).ChangeToFrameIndex(OpToFold.getIndex());
UseMI->RemoveOperand(2); // Remove exec read (or src1 for readlane)
return;
}
if (OpToFold.isReg() && TRI->isSGPRReg(*MRI, OpToFold.getReg())) {
if (execMayBeModifiedBeforeUse(*MRI,
UseMI->getOperand(UseOpIdx).getReg(),
*OpToFold.getParent(),
*UseMI))
return;
// %vgpr = COPY %sgpr0
// %sgpr1 = V_READFIRSTLANE_B32 %vgpr
// =>
// %sgpr1 = COPY %sgpr0
UseMI->setDesc(TII->get(AMDGPU::COPY));
UseMI->getOperand(1).setReg(OpToFold.getReg());
UseMI->getOperand(1).setSubReg(OpToFold.getSubReg());
UseMI->getOperand(1).setIsKill(false);
UseMI->RemoveOperand(2); // Remove exec read (or src1 for readlane)
return;
}
}
const MCInstrDesc &UseDesc = UseMI->getDesc();
// Don't fold into target independent nodes. Target independent opcodes
// don't have defined register classes.
if (UseDesc.isVariadic() ||
UseOp.isImplicit() ||
UseDesc.OpInfo[UseOpIdx].RegClass == -1)
return;
}
if (!FoldingImmLike) {
tryAddToFoldList(FoldList, UseMI, UseOpIdx, &OpToFold, TII);
// FIXME: We could try to change the instruction from 64-bit to 32-bit
// to enable more folding opportunites. The shrink operands pass
// already does this.
return;
}
const MCInstrDesc &FoldDesc = OpToFold.getParent()->getDesc();
const TargetRegisterClass *FoldRC =
TRI->getRegClass(FoldDesc.OpInfo[0].RegClass);
// Split 64-bit constants into 32-bits for folding.
if (UseOp.getSubReg() && AMDGPU::getRegBitWidth(FoldRC->getID()) == 64) {
Register UseReg = UseOp.getReg();
const TargetRegisterClass *UseRC = MRI->getRegClass(UseReg);
if (AMDGPU::getRegBitWidth(UseRC->getID()) != 64)
return;
APInt Imm(64, OpToFold.getImm());
if (UseOp.getSubReg() == AMDGPU::sub0) {
Imm = Imm.getLoBits(32);
} else {
assert(UseOp.getSubReg() == AMDGPU::sub1);
Imm = Imm.getHiBits(32);
}
MachineOperand ImmOp = MachineOperand::CreateImm(Imm.getSExtValue());
tryAddToFoldList(FoldList, UseMI, UseOpIdx, &ImmOp, TII);
return;
}
tryAddToFoldList(FoldList, UseMI, UseOpIdx, &OpToFold, TII);
}
static bool evalBinaryInstruction(unsigned Opcode, int32_t &Result,
uint32_t LHS, uint32_t RHS) {
switch (Opcode) {
case AMDGPU::V_AND_B32_e64:
case AMDGPU::V_AND_B32_e32:
case AMDGPU::S_AND_B32:
Result = LHS & RHS;
return true;
case AMDGPU::V_OR_B32_e64:
case AMDGPU::V_OR_B32_e32:
case AMDGPU::S_OR_B32:
Result = LHS | RHS;
return true;
case AMDGPU::V_XOR_B32_e64:
case AMDGPU::V_XOR_B32_e32:
case AMDGPU::S_XOR_B32:
Result = LHS ^ RHS;
return true;
case AMDGPU::V_LSHL_B32_e64:
case AMDGPU::V_LSHL_B32_e32:
case AMDGPU::S_LSHL_B32:
// The instruction ignores the high bits for out of bounds shifts.
Result = LHS << (RHS & 31);
return true;
case AMDGPU::V_LSHLREV_B32_e64:
case AMDGPU::V_LSHLREV_B32_e32:
Result = RHS << (LHS & 31);
return true;
case AMDGPU::V_LSHR_B32_e64:
case AMDGPU::V_LSHR_B32_e32:
case AMDGPU::S_LSHR_B32:
Result = LHS >> (RHS & 31);
return true;
case AMDGPU::V_LSHRREV_B32_e64:
case AMDGPU::V_LSHRREV_B32_e32:
Result = RHS >> (LHS & 31);
return true;
case AMDGPU::V_ASHR_I32_e64:
case AMDGPU::V_ASHR_I32_e32:
case AMDGPU::S_ASHR_I32:
Result = static_cast<int32_t>(LHS) >> (RHS & 31);
return true;
case AMDGPU::V_ASHRREV_I32_e64:
case AMDGPU::V_ASHRREV_I32_e32:
Result = static_cast<int32_t>(RHS) >> (LHS & 31);
return true;
default:
return false;
}
}
static unsigned getMovOpc(bool IsScalar) {
return IsScalar ? AMDGPU::S_MOV_B32 : AMDGPU::V_MOV_B32_e32;
}
/// Remove any leftover implicit operands from mutating the instruction. e.g.
/// if we replace an s_and_b32 with a copy, we don't need the implicit scc def
/// anymore.
static void stripExtraCopyOperands(MachineInstr &MI) {
const MCInstrDesc &Desc = MI.getDesc();
unsigned NumOps = Desc.getNumOperands() +
Desc.getNumImplicitUses() +
Desc.getNumImplicitDefs();
for (unsigned I = MI.getNumOperands() - 1; I >= NumOps; --I)
MI.RemoveOperand(I);
}
static void mutateCopyOp(MachineInstr &MI, const MCInstrDesc &NewDesc) {
MI.setDesc(NewDesc);
stripExtraCopyOperands(MI);
}
static MachineOperand *getImmOrMaterializedImm(MachineRegisterInfo &MRI,
MachineOperand &Op) {
if (Op.isReg()) {
// If this has a subregister, it obviously is a register source.
if (Op.getSubReg() != AMDGPU::NoSubRegister ||
!Register::isVirtualRegister(Op.getReg()))
return &Op;
MachineInstr *Def = MRI.getVRegDef(Op.getReg());
if (Def && Def->isMoveImmediate()) {
MachineOperand &ImmSrc = Def->getOperand(1);
if (ImmSrc.isImm())
return &ImmSrc;
}
}
return &Op;
}
// Try to simplify operations with a constant that may appear after instruction
// selection.
// TODO: See if a frame index with a fixed offset can fold.
static bool tryConstantFoldOp(MachineRegisterInfo &MRI,
const SIInstrInfo *TII,
MachineInstr *MI,
MachineOperand *ImmOp) {
unsigned Opc = MI->getOpcode();
if (Opc == AMDGPU::V_NOT_B32_e64 || Opc == AMDGPU::V_NOT_B32_e32 ||
Opc == AMDGPU::S_NOT_B32) {
MI->getOperand(1).ChangeToImmediate(~ImmOp->getImm());
mutateCopyOp(*MI, TII->get(getMovOpc(Opc == AMDGPU::S_NOT_B32)));
return true;
}
int Src1Idx = AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::src1);
if (Src1Idx == -1)
return false;
int Src0Idx = AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::src0);
MachineOperand *Src0 = getImmOrMaterializedImm(MRI, MI->getOperand(Src0Idx));
MachineOperand *Src1 = getImmOrMaterializedImm(MRI, MI->getOperand(Src1Idx));
if (!Src0->isImm() && !Src1->isImm())
return false;
if (MI->getOpcode() == AMDGPU::V_LSHL_OR_B32) {
if (Src0->isImm() && Src0->getImm() == 0) {
// v_lshl_or_b32 0, X, Y -> copy Y
// v_lshl_or_b32 0, X, K -> v_mov_b32 K
bool UseCopy = TII->getNamedOperand(*MI, AMDGPU::OpName::src2)->isReg();
MI->RemoveOperand(Src1Idx);
MI->RemoveOperand(Src0Idx);
MI->setDesc(TII->get(UseCopy ? AMDGPU::COPY : AMDGPU::V_MOV_B32_e32));
return true;
}
}
// and k0, k1 -> v_mov_b32 (k0 & k1)
// or k0, k1 -> v_mov_b32 (k0 | k1)
// xor k0, k1 -> v_mov_b32 (k0 ^ k1)
if (Src0->isImm() && Src1->isImm()) {
int32_t NewImm;
if (!evalBinaryInstruction(Opc, NewImm, Src0->getImm(), Src1->getImm()))
return false;
const SIRegisterInfo &TRI = TII->getRegisterInfo();
bool IsSGPR = TRI.isSGPRReg(MRI, MI->getOperand(0).getReg());
// Be careful to change the right operand, src0 may belong to a different
// instruction.
MI->getOperand(Src0Idx).ChangeToImmediate(NewImm);
MI->RemoveOperand(Src1Idx);
mutateCopyOp(*MI, TII->get(getMovOpc(IsSGPR)));
return true;
}
if (!MI->isCommutable())
return false;
if (Src0->isImm() && !Src1->isImm()) {
std::swap(Src0, Src1);
std::swap(Src0Idx, Src1Idx);
}
int32_t Src1Val = static_cast<int32_t>(Src1->getImm());
if (Opc == AMDGPU::V_OR_B32_e64 ||
Opc == AMDGPU::V_OR_B32_e32 ||
Opc == AMDGPU::S_OR_B32) {
if (Src1Val == 0) {
// y = or x, 0 => y = copy x
MI->RemoveOperand(Src1Idx);
mutateCopyOp(*MI, TII->get(AMDGPU::COPY));
} else if (Src1Val == -1) {
// y = or x, -1 => y = v_mov_b32 -1
MI->RemoveOperand(Src1Idx);
mutateCopyOp(*MI, TII->get(getMovOpc(Opc == AMDGPU::S_OR_B32)));
} else
return false;
return true;
}
if (MI->getOpcode() == AMDGPU::V_AND_B32_e64 ||
MI->getOpcode() == AMDGPU::V_AND_B32_e32 ||
MI->getOpcode() == AMDGPU::S_AND_B32) {
if (Src1Val == 0) {
// y = and x, 0 => y = v_mov_b32 0
MI->RemoveOperand(Src0Idx);
mutateCopyOp(*MI, TII->get(getMovOpc(Opc == AMDGPU::S_AND_B32)));
} else if (Src1Val == -1) {
// y = and x, -1 => y = copy x
MI->RemoveOperand(Src1Idx);
mutateCopyOp(*MI, TII->get(AMDGPU::COPY));
stripExtraCopyOperands(*MI);
} else
return false;
return true;
}
if (MI->getOpcode() == AMDGPU::V_XOR_B32_e64 ||
MI->getOpcode() == AMDGPU::V_XOR_B32_e32 ||
MI->getOpcode() == AMDGPU::S_XOR_B32) {
if (Src1Val == 0) {
// y = xor x, 0 => y = copy x
MI->RemoveOperand(Src1Idx);
mutateCopyOp(*MI, TII->get(AMDGPU::COPY));
return true;
}
}
return false;
}
// Try to fold an instruction into a simpler one
static bool tryFoldInst(const SIInstrInfo *TII,
MachineInstr *MI) {
unsigned Opc = MI->getOpcode();
if (Opc == AMDGPU::V_CNDMASK_B32_e32 ||
Opc == AMDGPU::V_CNDMASK_B32_e64 ||
Opc == AMDGPU::V_CNDMASK_B64_PSEUDO) {
const MachineOperand *Src0 = TII->getNamedOperand(*MI, AMDGPU::OpName::src0);
const MachineOperand *Src1 = TII->getNamedOperand(*MI, AMDGPU::OpName::src1);
int Src1ModIdx = AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::src1_modifiers);
int Src0ModIdx = AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::src0_modifiers);
if (Src1->isIdenticalTo(*Src0) &&
(Src1ModIdx == -1 || !MI->getOperand(Src1ModIdx).getImm()) &&
(Src0ModIdx == -1 || !MI->getOperand(Src0ModIdx).getImm())) {
LLVM_DEBUG(dbgs() << "Folded " << *MI << " into ");
auto &NewDesc =
TII->get(Src0->isReg() ? (unsigned)AMDGPU::COPY : getMovOpc(false));
int Src2Idx = AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::src2);
if (Src2Idx != -1)
MI->RemoveOperand(Src2Idx);
MI->RemoveOperand(AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::src1));
if (Src1ModIdx != -1)
MI->RemoveOperand(Src1ModIdx);
if (Src0ModIdx != -1)
MI->RemoveOperand(Src0ModIdx);
mutateCopyOp(*MI, NewDesc);
LLVM_DEBUG(dbgs() << *MI << '\n');
return true;
}
}