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llvm-project/llvm/lib/Target/AMDGPU/AMDGPUMCInstLower.cpp

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//===- AMDGPUMCInstLower.cpp - Lower AMDGPU MachineInstr to an MCInst -----===//
//
// 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
/// Code to lower AMDGPU MachineInstrs to their corresponding MCInst.
//
//===----------------------------------------------------------------------===//
//
#include "AMDGPUAsmPrinter.h"
#include "AMDGPUSubtarget.h"
#include "AMDGPUTargetMachine.h"
#include "MCTargetDesc/AMDGPUInstPrinter.h"
#include "MCTargetDesc/AMDGPUMCTargetDesc.h"
#include "R600AsmPrinter.h"
#include "SIInstrInfo.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/MC/MCCodeEmitter.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCObjectStreamer.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Format.h"
#include <algorithm>
using namespace llvm;
namespace {
class AMDGPUMCInstLower {
MCContext &Ctx;
const TargetSubtargetInfo &ST;
const AsmPrinter &AP;
const MCExpr *getLongBranchBlockExpr(const MachineBasicBlock &SrcBB,
const MachineOperand &MO) const;
public:
AMDGPUMCInstLower(MCContext &ctx, const TargetSubtargetInfo &ST,
const AsmPrinter &AP);
bool lowerOperand(const MachineOperand &MO, MCOperand &MCOp) const;
/// Lower a MachineInstr to an MCInst
void lower(const MachineInstr *MI, MCInst &OutMI) const;
};
class R600MCInstLower : public AMDGPUMCInstLower {
public:
R600MCInstLower(MCContext &ctx, const R600Subtarget &ST,
const AsmPrinter &AP);
/// Lower a MachineInstr to an MCInst
void lower(const MachineInstr *MI, MCInst &OutMI) const;
};
} // End anonymous namespace
#include "AMDGPUGenMCPseudoLowering.inc"
AMDGPUMCInstLower::AMDGPUMCInstLower(MCContext &ctx,
const TargetSubtargetInfo &st,
const AsmPrinter &ap):
Ctx(ctx), ST(st), AP(ap) { }
static MCSymbolRefExpr::VariantKind getVariantKind(unsigned MOFlags) {
switch (MOFlags) {
default:
return MCSymbolRefExpr::VK_None;
case SIInstrInfo::MO_GOTPCREL:
return MCSymbolRefExpr::VK_GOTPCREL;
case SIInstrInfo::MO_GOTPCREL32_LO:
return MCSymbolRefExpr::VK_AMDGPU_GOTPCREL32_LO;
case SIInstrInfo::MO_GOTPCREL32_HI:
return MCSymbolRefExpr::VK_AMDGPU_GOTPCREL32_HI;
case SIInstrInfo::MO_REL32_LO:
return MCSymbolRefExpr::VK_AMDGPU_REL32_LO;
case SIInstrInfo::MO_REL32_HI:
return MCSymbolRefExpr::VK_AMDGPU_REL32_HI;
case SIInstrInfo::MO_ABS32_LO:
return MCSymbolRefExpr::VK_AMDGPU_ABS32_LO;
case SIInstrInfo::MO_ABS32_HI:
return MCSymbolRefExpr::VK_AMDGPU_ABS32_HI;
}
}
const MCExpr *AMDGPUMCInstLower::getLongBranchBlockExpr(
const MachineBasicBlock &SrcBB,
const MachineOperand &MO) const {
const MCExpr *DestBBSym
= MCSymbolRefExpr::create(MO.getMBB()->getSymbol(), Ctx);
const MCExpr *SrcBBSym = MCSymbolRefExpr::create(SrcBB.getSymbol(), Ctx);
// FIXME: The first half of this assert should be removed. This should
// probably be PC relative instead of using the source block symbol, and
// therefore the indirect branch expansion should use a bundle.
assert(
skipDebugInstructionsForward(SrcBB.begin(), SrcBB.end())->getOpcode() ==
AMDGPU::S_GETPC_B64 &&
ST.getInstrInfo()->get(AMDGPU::S_GETPC_B64).Size == 4);
// s_getpc_b64 returns the address of next instruction.
const MCConstantExpr *One = MCConstantExpr::create(4, Ctx);
SrcBBSym = MCBinaryExpr::createAdd(SrcBBSym, One, Ctx);
if (MO.getTargetFlags() == SIInstrInfo::MO_LONG_BRANCH_FORWARD)
return MCBinaryExpr::createSub(DestBBSym, SrcBBSym, Ctx);
assert(MO.getTargetFlags() == SIInstrInfo::MO_LONG_BRANCH_BACKWARD);
return MCBinaryExpr::createSub(SrcBBSym, DestBBSym, Ctx);
}
bool AMDGPUMCInstLower::lowerOperand(const MachineOperand &MO,
MCOperand &MCOp) const {
switch (MO.getType()) {
default:
llvm_unreachable("unknown operand type");
case MachineOperand::MO_Immediate:
MCOp = MCOperand::createImm(MO.getImm());
return true;
case MachineOperand::MO_Register:
MCOp = MCOperand::createReg(AMDGPU::getMCReg(MO.getReg(), ST));
return true;
case MachineOperand::MO_MachineBasicBlock: {
if (MO.getTargetFlags() != 0) {
MCOp = MCOperand::createExpr(
getLongBranchBlockExpr(*MO.getParent()->getParent(), MO));
} else {
MCOp = MCOperand::createExpr(
MCSymbolRefExpr::create(MO.getMBB()->getSymbol(), Ctx));
}
return true;
}
case MachineOperand::MO_GlobalAddress: {
const GlobalValue *GV = MO.getGlobal();
SmallString<128> SymbolName;
AP.getNameWithPrefix(SymbolName, GV);
MCSymbol *Sym = Ctx.getOrCreateSymbol(SymbolName);
const MCExpr *Expr =
MCSymbolRefExpr::create(Sym, getVariantKind(MO.getTargetFlags()),Ctx);
int64_t Offset = MO.getOffset();
if (Offset != 0) {
Expr = MCBinaryExpr::createAdd(Expr,
MCConstantExpr::create(Offset, Ctx), Ctx);
}
MCOp = MCOperand::createExpr(Expr);
return true;
}
case MachineOperand::MO_ExternalSymbol: {
MCSymbol *Sym = Ctx.getOrCreateSymbol(StringRef(MO.getSymbolName()));
Sym->setExternal(true);
const MCSymbolRefExpr *Expr = MCSymbolRefExpr::create(Sym, Ctx);
MCOp = MCOperand::createExpr(Expr);
return true;
}
case MachineOperand::MO_RegisterMask:
// Regmasks are like implicit defs.
return false;
}
}
void AMDGPUMCInstLower::lower(const MachineInstr *MI, MCInst &OutMI) const {
unsigned Opcode = MI->getOpcode();
const auto *TII = static_cast<const SIInstrInfo*>(ST.getInstrInfo());
// FIXME: Should be able to handle this with emitPseudoExpansionLowering. We
// need to select it to the subtarget specific version, and there's no way to
// do that with a single pseudo source operation.
if (Opcode == AMDGPU::S_SETPC_B64_return)
Opcode = AMDGPU::S_SETPC_B64;
else if (Opcode == AMDGPU::SI_CALL) {
// SI_CALL is just S_SWAPPC_B64 with an additional operand to track the
// called function (which we need to remove here).
OutMI.setOpcode(TII->pseudoToMCOpcode(AMDGPU::S_SWAPPC_B64));
MCOperand Dest, Src;
lowerOperand(MI->getOperand(0), Dest);
lowerOperand(MI->getOperand(1), Src);
OutMI.addOperand(Dest);
OutMI.addOperand(Src);
return;
} else if (Opcode == AMDGPU::SI_TCRETURN) {
// TODO: How to use branch immediate and avoid register+add?
Opcode = AMDGPU::S_SETPC_B64;
}
int MCOpcode = TII->pseudoToMCOpcode(Opcode);
if (MCOpcode == -1) {
LLVMContext &C = MI->getParent()->getParent()->getFunction().getContext();
C.emitError("AMDGPUMCInstLower::lower - Pseudo instruction doesn't have "
"a target-specific version: " + Twine(MI->getOpcode()));
}
OutMI.setOpcode(MCOpcode);
for (const MachineOperand &MO : MI->explicit_operands()) {
MCOperand MCOp;
lowerOperand(MO, MCOp);
OutMI.addOperand(MCOp);
}
int FIIdx = AMDGPU::getNamedOperandIdx(MCOpcode, AMDGPU::OpName::fi);
if (FIIdx >= (int)OutMI.getNumOperands())
OutMI.addOperand(MCOperand::createImm(0));
}
bool AMDGPUAsmPrinter::lowerOperand(const MachineOperand &MO,
MCOperand &MCOp) const {
const GCNSubtarget &STI = MF->getSubtarget<GCNSubtarget>();
AMDGPUMCInstLower MCInstLowering(OutContext, STI, *this);
return MCInstLowering.lowerOperand(MO, MCOp);
}
static const MCExpr *lowerAddrSpaceCast(const TargetMachine &TM,
const Constant *CV,
MCContext &OutContext) {
// TargetMachine does not support llvm-style cast. Use C++-style cast.
// This is safe since TM is always of type AMDGPUTargetMachine or its
// derived class.
auto &AT = static_cast<const AMDGPUTargetMachine&>(TM);
auto *CE = dyn_cast<ConstantExpr>(CV);
// Lower null pointers in private and local address space.
// Clang generates addrspacecast for null pointers in private and local
// address space, which needs to be lowered.
if (CE && CE->getOpcode() == Instruction::AddrSpaceCast) {
auto Op = CE->getOperand(0);
auto SrcAddr = Op->getType()->getPointerAddressSpace();
if (Op->isNullValue() && AT.getNullPointerValue(SrcAddr) == 0) {
auto DstAddr = CE->getType()->getPointerAddressSpace();
return MCConstantExpr::create(AT.getNullPointerValue(DstAddr),
OutContext);
}
}
return nullptr;
}
const MCExpr *AMDGPUAsmPrinter::lowerConstant(const Constant *CV) {
if (const MCExpr *E = lowerAddrSpaceCast(TM, CV, OutContext))
return E;
return AsmPrinter::lowerConstant(CV);
}
void AMDGPUAsmPrinter::emitInstruction(const MachineInstr *MI) {
if (emitPseudoExpansionLowering(*OutStreamer, MI))
return;
const GCNSubtarget &STI = MF->getSubtarget<GCNSubtarget>();
AMDGPUMCInstLower MCInstLowering(OutContext, STI, *this);
StringRef Err;
if (!STI.getInstrInfo()->verifyInstruction(*MI, Err)) {
LLVMContext &C = MI->getParent()->getParent()->getFunction().getContext();
C.emitError("Illegal instruction detected: " + Err);
MI->print(errs());
}
if (MI->isBundle()) {
const MachineBasicBlock *MBB = MI->getParent();
MachineBasicBlock::const_instr_iterator I = ++MI->getIterator();
while (I != MBB->instr_end() && I->isInsideBundle()) {
emitInstruction(&*I);
++I;
}
} else {
// We don't want SI_MASK_BRANCH/SI_RETURN_TO_EPILOG encoded. They are
// placeholder terminator instructions and should only be printed as
// comments.
if (MI->getOpcode() == AMDGPU::SI_MASK_BRANCH) {
if (isVerbose()) {
SmallVector<char, 16> BBStr;
raw_svector_ostream Str(BBStr);
const MachineBasicBlock *MBB = MI->getOperand(0).getMBB();
const MCSymbolRefExpr *Expr
= MCSymbolRefExpr::create(MBB->getSymbol(), OutContext);
Expr->print(Str, MAI);
OutStreamer->emitRawComment(Twine(" mask branch ") + BBStr);
}
return;
}
if (MI->getOpcode() == AMDGPU::SI_RETURN_TO_EPILOG) {
if (isVerbose())
OutStreamer->emitRawComment(" return to shader part epilog");
return;
}
if (MI->getOpcode() == AMDGPU::WAVE_BARRIER) {
if (isVerbose())
OutStreamer->emitRawComment(" wave barrier");
return;
}
if (MI->getOpcode() == AMDGPU::SI_MASKED_UNREACHABLE) {
if (isVerbose())
OutStreamer->emitRawComment(" divergent unreachable");
return;
}
MCInst TmpInst;
MCInstLowering.lower(MI, TmpInst);
EmitToStreamer(*OutStreamer, TmpInst);
#ifdef EXPENSIVE_CHECKS
// Sanity-check getInstSizeInBytes on explicitly specified CPUs (it cannot
// work correctly for the generic CPU).
//
// The isPseudo check really shouldn't be here, but unfortunately there are
// some negative lit tests that depend on being able to continue through
// here even when pseudo instructions haven't been lowered.
if (!MI->isPseudo() && STI.isCPUStringValid(STI.getCPU())) {
SmallVector<MCFixup, 4> Fixups;
SmallVector<char, 16> CodeBytes;
raw_svector_ostream CodeStream(CodeBytes);
std::unique_ptr<MCCodeEmitter> InstEmitter(createSIMCCodeEmitter(
*STI.getInstrInfo(), *OutContext.getRegisterInfo(), OutContext));
InstEmitter->encodeInstruction(TmpInst, CodeStream, Fixups, STI);
assert(CodeBytes.size() == STI.getInstrInfo()->getInstSizeInBytes(*MI));
}
#endif
if (DumpCodeInstEmitter) {
// Disassemble instruction/operands to text
DisasmLines.resize(DisasmLines.size() + 1);
std::string &DisasmLine = DisasmLines.back();
raw_string_ostream DisasmStream(DisasmLine);
AMDGPUInstPrinter InstPrinter(*TM.getMCAsmInfo(), *STI.getInstrInfo(),
*STI.getRegisterInfo());
InstPrinter.printInst(&TmpInst, 0, StringRef(), STI, DisasmStream);
// Disassemble instruction/operands to hex representation.
SmallVector<MCFixup, 4> Fixups;
SmallVector<char, 16> CodeBytes;
raw_svector_ostream CodeStream(CodeBytes);
DumpCodeInstEmitter->encodeInstruction(
TmpInst, CodeStream, Fixups, MF->getSubtarget<MCSubtargetInfo>());
HexLines.resize(HexLines.size() + 1);
std::string &HexLine = HexLines.back();
raw_string_ostream HexStream(HexLine);
for (size_t i = 0; i < CodeBytes.size(); i += 4) {
unsigned int CodeDWord = *(unsigned int *)&CodeBytes[i];
HexStream << format("%s%08X", (i > 0 ? " " : ""), CodeDWord);
}
DisasmStream.flush();
DisasmLineMaxLen = std::max(DisasmLineMaxLen, DisasmLine.size());
}
}
}
R600MCInstLower::R600MCInstLower(MCContext &Ctx, const R600Subtarget &ST,
const AsmPrinter &AP) :
AMDGPUMCInstLower(Ctx, ST, AP) { }
void R600MCInstLower::lower(const MachineInstr *MI, MCInst &OutMI) const {
OutMI.setOpcode(MI->getOpcode());
for (const MachineOperand &MO : MI->explicit_operands()) {
MCOperand MCOp;
lowerOperand(MO, MCOp);
OutMI.addOperand(MCOp);
}
}
void R600AsmPrinter::emitInstruction(const MachineInstr *MI) {
const R600Subtarget &STI = MF->getSubtarget<R600Subtarget>();
R600MCInstLower MCInstLowering(OutContext, STI, *this);
StringRef Err;
if (!STI.getInstrInfo()->verifyInstruction(*MI, Err)) {
LLVMContext &C = MI->getParent()->getParent()->getFunction().getContext();
C.emitError("Illegal instruction detected: " + Err);
MI->print(errs());
}
if (MI->isBundle()) {
const MachineBasicBlock *MBB = MI->getParent();
MachineBasicBlock::const_instr_iterator I = ++MI->getIterator();
while (I != MBB->instr_end() && I->isInsideBundle()) {
emitInstruction(&*I);
++I;
}
} else {
MCInst TmpInst;
MCInstLowering.lower(MI, TmpInst);
EmitToStreamer(*OutStreamer, TmpInst);
}
}
const MCExpr *R600AsmPrinter::lowerConstant(const Constant *CV) {
if (const MCExpr *E = lowerAddrSpaceCast(TM, CV, OutContext))
return E;
return AsmPrinter::lowerConstant(CV);
}
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