1 //===- AMDGPUMCInstLower.cpp - Lower AMDGPU MachineInstr to an MCInst -----===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 /// \file 10 /// Code to lower AMDGPU MachineInstrs to their corresponding MCInst. 11 // 12 //===----------------------------------------------------------------------===// 13 // 14 15 #include "AMDGPUAsmPrinter.h" 16 #include "AMDGPUSubtarget.h" 17 #include "AMDGPUTargetMachine.h" 18 #include "MCTargetDesc/AMDGPUInstPrinter.h" 19 #include "MCTargetDesc/AMDGPUMCTargetDesc.h" 20 #include "R600AsmPrinter.h" 21 #include "SIInstrInfo.h" 22 #include "llvm/CodeGen/MachineBasicBlock.h" 23 #include "llvm/CodeGen/MachineInstr.h" 24 #include "llvm/IR/Constants.h" 25 #include "llvm/IR/Function.h" 26 #include "llvm/IR/GlobalVariable.h" 27 #include "llvm/MC/MCCodeEmitter.h" 28 #include "llvm/MC/MCContext.h" 29 #include "llvm/MC/MCExpr.h" 30 #include "llvm/MC/MCInst.h" 31 #include "llvm/MC/MCObjectStreamer.h" 32 #include "llvm/MC/MCStreamer.h" 33 #include "llvm/Support/ErrorHandling.h" 34 #include "llvm/Support/Format.h" 35 #include <algorithm> 36 37 using namespace llvm; 38 39 namespace { 40 41 class AMDGPUMCInstLower { 42 MCContext &Ctx; 43 const TargetSubtargetInfo &ST; 44 const AsmPrinter &AP; 45 46 const MCExpr *getLongBranchBlockExpr(const MachineBasicBlock &SrcBB, 47 const MachineOperand &MO) const; 48 49 public: 50 AMDGPUMCInstLower(MCContext &ctx, const TargetSubtargetInfo &ST, 51 const AsmPrinter &AP); 52 53 bool lowerOperand(const MachineOperand &MO, MCOperand &MCOp) const; 54 55 /// Lower a MachineInstr to an MCInst 56 void lower(const MachineInstr *MI, MCInst &OutMI) const; 57 58 }; 59 60 class R600MCInstLower : public AMDGPUMCInstLower { 61 public: 62 R600MCInstLower(MCContext &ctx, const R600Subtarget &ST, 63 const AsmPrinter &AP); 64 65 /// Lower a MachineInstr to an MCInst 66 void lower(const MachineInstr *MI, MCInst &OutMI) const; 67 }; 68 69 70 } // End anonymous namespace 71 72 #include "AMDGPUGenMCPseudoLowering.inc" 73 74 AMDGPUMCInstLower::AMDGPUMCInstLower(MCContext &ctx, 75 const TargetSubtargetInfo &st, 76 const AsmPrinter &ap): 77 Ctx(ctx), ST(st), AP(ap) { } 78 79 static MCSymbolRefExpr::VariantKind getVariantKind(unsigned MOFlags) { 80 switch (MOFlags) { 81 default: 82 return MCSymbolRefExpr::VK_None; 83 case SIInstrInfo::MO_GOTPCREL: 84 return MCSymbolRefExpr::VK_GOTPCREL; 85 case SIInstrInfo::MO_GOTPCREL32_LO: 86 return MCSymbolRefExpr::VK_AMDGPU_GOTPCREL32_LO; 87 case SIInstrInfo::MO_GOTPCREL32_HI: 88 return MCSymbolRefExpr::VK_AMDGPU_GOTPCREL32_HI; 89 case SIInstrInfo::MO_REL32_LO: 90 return MCSymbolRefExpr::VK_AMDGPU_REL32_LO; 91 case SIInstrInfo::MO_REL32_HI: 92 return MCSymbolRefExpr::VK_AMDGPU_REL32_HI; 93 case SIInstrInfo::MO_ABS32_LO: 94 return MCSymbolRefExpr::VK_AMDGPU_ABS32_LO; 95 case SIInstrInfo::MO_ABS32_HI: 96 return MCSymbolRefExpr::VK_AMDGPU_ABS32_HI; 97 } 98 } 99 100 const MCExpr *AMDGPUMCInstLower::getLongBranchBlockExpr( 101 const MachineBasicBlock &SrcBB, 102 const MachineOperand &MO) const { 103 const MCExpr *DestBBSym 104 = MCSymbolRefExpr::create(MO.getMBB()->getSymbol(), Ctx); 105 const MCExpr *SrcBBSym = MCSymbolRefExpr::create(SrcBB.getSymbol(), Ctx); 106 107 // FIXME: The first half of this assert should be removed. This should 108 // probably be PC relative instead of using the source block symbol, and 109 // therefore the indirect branch expansion should use a bundle. 110 assert( 111 skipDebugInstructionsForward(SrcBB.begin(), SrcBB.end())->getOpcode() == 112 AMDGPU::S_GETPC_B64 && 113 ST.getInstrInfo()->get(AMDGPU::S_GETPC_B64).Size == 4); 114 115 // s_getpc_b64 returns the address of next instruction. 116 const MCConstantExpr *One = MCConstantExpr::create(4, Ctx); 117 SrcBBSym = MCBinaryExpr::createAdd(SrcBBSym, One, Ctx); 118 119 if (MO.getTargetFlags() == SIInstrInfo::MO_LONG_BRANCH_FORWARD) 120 return MCBinaryExpr::createSub(DestBBSym, SrcBBSym, Ctx); 121 122 assert(MO.getTargetFlags() == SIInstrInfo::MO_LONG_BRANCH_BACKWARD); 123 return MCBinaryExpr::createSub(SrcBBSym, DestBBSym, Ctx); 124 } 125 126 bool AMDGPUMCInstLower::lowerOperand(const MachineOperand &MO, 127 MCOperand &MCOp) const { 128 switch (MO.getType()) { 129 default: 130 llvm_unreachable("unknown operand type"); 131 case MachineOperand::MO_Immediate: 132 MCOp = MCOperand::createImm(MO.getImm()); 133 return true; 134 case MachineOperand::MO_Register: 135 MCOp = MCOperand::createReg(AMDGPU::getMCReg(MO.getReg(), ST)); 136 return true; 137 case MachineOperand::MO_MachineBasicBlock: { 138 if (MO.getTargetFlags() != 0) { 139 MCOp = MCOperand::createExpr( 140 getLongBranchBlockExpr(*MO.getParent()->getParent(), MO)); 141 } else { 142 MCOp = MCOperand::createExpr( 143 MCSymbolRefExpr::create(MO.getMBB()->getSymbol(), Ctx)); 144 } 145 146 return true; 147 } 148 case MachineOperand::MO_GlobalAddress: { 149 const GlobalValue *GV = MO.getGlobal(); 150 SmallString<128> SymbolName; 151 AP.getNameWithPrefix(SymbolName, GV); 152 MCSymbol *Sym = Ctx.getOrCreateSymbol(SymbolName); 153 const MCExpr *Expr = 154 MCSymbolRefExpr::create(Sym, getVariantKind(MO.getTargetFlags()),Ctx); 155 int64_t Offset = MO.getOffset(); 156 if (Offset != 0) { 157 Expr = MCBinaryExpr::createAdd(Expr, 158 MCConstantExpr::create(Offset, Ctx), Ctx); 159 } 160 MCOp = MCOperand::createExpr(Expr); 161 return true; 162 } 163 case MachineOperand::MO_ExternalSymbol: { 164 MCSymbol *Sym = Ctx.getOrCreateSymbol(StringRef(MO.getSymbolName())); 165 Sym->setExternal(true); 166 const MCSymbolRefExpr *Expr = MCSymbolRefExpr::create(Sym, Ctx); 167 MCOp = MCOperand::createExpr(Expr); 168 return true; 169 } 170 case MachineOperand::MO_RegisterMask: 171 // Regmasks are like implicit defs. 172 return false; 173 } 174 } 175 176 void AMDGPUMCInstLower::lower(const MachineInstr *MI, MCInst &OutMI) const { 177 unsigned Opcode = MI->getOpcode(); 178 const auto *TII = static_cast<const SIInstrInfo*>(ST.getInstrInfo()); 179 180 // FIXME: Should be able to handle this with emitPseudoExpansionLowering. We 181 // need to select it to the subtarget specific version, and there's no way to 182 // do that with a single pseudo source operation. 183 if (Opcode == AMDGPU::S_SETPC_B64_return) 184 Opcode = AMDGPU::S_SETPC_B64; 185 else if (Opcode == AMDGPU::SI_CALL) { 186 // SI_CALL is just S_SWAPPC_B64 with an additional operand to track the 187 // called function (which we need to remove here). 188 OutMI.setOpcode(TII->pseudoToMCOpcode(AMDGPU::S_SWAPPC_B64)); 189 MCOperand Dest, Src; 190 lowerOperand(MI->getOperand(0), Dest); 191 lowerOperand(MI->getOperand(1), Src); 192 OutMI.addOperand(Dest); 193 OutMI.addOperand(Src); 194 return; 195 } else if (Opcode == AMDGPU::SI_TCRETURN) { 196 // TODO: How to use branch immediate and avoid register+add? 197 Opcode = AMDGPU::S_SETPC_B64; 198 } 199 200 int MCOpcode = TII->pseudoToMCOpcode(Opcode); 201 if (MCOpcode == -1) { 202 LLVMContext &C = MI->getParent()->getParent()->getFunction().getContext(); 203 C.emitError("AMDGPUMCInstLower::lower - Pseudo instruction doesn't have " 204 "a target-specific version: " + Twine(MI->getOpcode())); 205 } 206 207 OutMI.setOpcode(MCOpcode); 208 209 for (const MachineOperand &MO : MI->explicit_operands()) { 210 MCOperand MCOp; 211 lowerOperand(MO, MCOp); 212 OutMI.addOperand(MCOp); 213 } 214 } 215 216 bool AMDGPUAsmPrinter::lowerOperand(const MachineOperand &MO, 217 MCOperand &MCOp) const { 218 const GCNSubtarget &STI = MF->getSubtarget<GCNSubtarget>(); 219 AMDGPUMCInstLower MCInstLowering(OutContext, STI, *this); 220 return MCInstLowering.lowerOperand(MO, MCOp); 221 } 222 223 static const MCExpr *lowerAddrSpaceCast(const TargetMachine &TM, 224 const Constant *CV, 225 MCContext &OutContext) { 226 // TargetMachine does not support llvm-style cast. Use C++-style cast. 227 // This is safe since TM is always of type AMDGPUTargetMachine or its 228 // derived class. 229 auto &AT = static_cast<const AMDGPUTargetMachine&>(TM); 230 auto *CE = dyn_cast<ConstantExpr>(CV); 231 232 // Lower null pointers in private and local address space. 233 // Clang generates addrspacecast for null pointers in private and local 234 // address space, which needs to be lowered. 235 if (CE && CE->getOpcode() == Instruction::AddrSpaceCast) { 236 auto Op = CE->getOperand(0); 237 auto SrcAddr = Op->getType()->getPointerAddressSpace(); 238 if (Op->isNullValue() && AT.getNullPointerValue(SrcAddr) == 0) { 239 auto DstAddr = CE->getType()->getPointerAddressSpace(); 240 return MCConstantExpr::create(AT.getNullPointerValue(DstAddr), 241 OutContext); 242 } 243 } 244 return nullptr; 245 } 246 247 const MCExpr *AMDGPUAsmPrinter::lowerConstant(const Constant *CV) { 248 if (const MCExpr *E = lowerAddrSpaceCast(TM, CV, OutContext)) 249 return E; 250 return AsmPrinter::lowerConstant(CV); 251 } 252 253 void AMDGPUAsmPrinter::EmitInstruction(const MachineInstr *MI) { 254 if (emitPseudoExpansionLowering(*OutStreamer, MI)) 255 return; 256 257 const GCNSubtarget &STI = MF->getSubtarget<GCNSubtarget>(); 258 AMDGPUMCInstLower MCInstLowering(OutContext, STI, *this); 259 260 StringRef Err; 261 if (!STI.getInstrInfo()->verifyInstruction(*MI, Err)) { 262 LLVMContext &C = MI->getParent()->getParent()->getFunction().getContext(); 263 C.emitError("Illegal instruction detected: " + Err); 264 MI->print(errs()); 265 } 266 267 if (MI->isBundle()) { 268 const MachineBasicBlock *MBB = MI->getParent(); 269 MachineBasicBlock::const_instr_iterator I = ++MI->getIterator(); 270 while (I != MBB->instr_end() && I->isInsideBundle()) { 271 EmitInstruction(&*I); 272 ++I; 273 } 274 } else { 275 // We don't want SI_MASK_BRANCH/SI_RETURN_TO_EPILOG encoded. They are 276 // placeholder terminator instructions and should only be printed as 277 // comments. 278 if (MI->getOpcode() == AMDGPU::SI_MASK_BRANCH) { 279 if (isVerbose()) { 280 SmallVector<char, 16> BBStr; 281 raw_svector_ostream Str(BBStr); 282 283 const MachineBasicBlock *MBB = MI->getOperand(0).getMBB(); 284 const MCSymbolRefExpr *Expr 285 = MCSymbolRefExpr::create(MBB->getSymbol(), OutContext); 286 Expr->print(Str, MAI); 287 OutStreamer->emitRawComment(Twine(" mask branch ") + BBStr); 288 } 289 290 return; 291 } 292 293 if (MI->getOpcode() == AMDGPU::SI_RETURN_TO_EPILOG) { 294 if (isVerbose()) 295 OutStreamer->emitRawComment(" return to shader part epilog"); 296 return; 297 } 298 299 if (MI->getOpcode() == AMDGPU::WAVE_BARRIER) { 300 if (isVerbose()) 301 OutStreamer->emitRawComment(" wave barrier"); 302 return; 303 } 304 305 if (MI->getOpcode() == AMDGPU::SI_MASKED_UNREACHABLE) { 306 if (isVerbose()) 307 OutStreamer->emitRawComment(" divergent unreachable"); 308 return; 309 } 310 311 MCInst TmpInst; 312 MCInstLowering.lower(MI, TmpInst); 313 EmitToStreamer(*OutStreamer, TmpInst); 314 315 #ifdef EXPENSIVE_CHECKS 316 // Sanity-check getInstSizeInBytes on explicitly specified CPUs (it cannot 317 // work correctly for the generic CPU). 318 // 319 // The isPseudo check really shouldn't be here, but unfortunately there are 320 // some negative lit tests that depend on being able to continue through 321 // here even when pseudo instructions haven't been lowered. 322 if (!MI->isPseudo() && STI.isCPUStringValid(STI.getCPU())) { 323 SmallVector<MCFixup, 4> Fixups; 324 SmallVector<char, 16> CodeBytes; 325 raw_svector_ostream CodeStream(CodeBytes); 326 327 std::unique_ptr<MCCodeEmitter> InstEmitter(createSIMCCodeEmitter( 328 *STI.getInstrInfo(), *OutContext.getRegisterInfo(), OutContext)); 329 InstEmitter->encodeInstruction(TmpInst, CodeStream, Fixups, STI); 330 331 assert(CodeBytes.size() == STI.getInstrInfo()->getInstSizeInBytes(*MI)); 332 } 333 #endif 334 335 if (DumpCodeInstEmitter) { 336 // Disassemble instruction/operands to text 337 DisasmLines.resize(DisasmLines.size() + 1); 338 std::string &DisasmLine = DisasmLines.back(); 339 raw_string_ostream DisasmStream(DisasmLine); 340 341 AMDGPUInstPrinter InstPrinter(*TM.getMCAsmInfo(), *STI.getInstrInfo(), 342 *STI.getRegisterInfo()); 343 InstPrinter.printInst(&TmpInst, DisasmStream, StringRef(), STI); 344 345 // Disassemble instruction/operands to hex representation. 346 SmallVector<MCFixup, 4> Fixups; 347 SmallVector<char, 16> CodeBytes; 348 raw_svector_ostream CodeStream(CodeBytes); 349 350 DumpCodeInstEmitter->encodeInstruction( 351 TmpInst, CodeStream, Fixups, MF->getSubtarget<MCSubtargetInfo>()); 352 HexLines.resize(HexLines.size() + 1); 353 std::string &HexLine = HexLines.back(); 354 raw_string_ostream HexStream(HexLine); 355 356 for (size_t i = 0; i < CodeBytes.size(); i += 4) { 357 unsigned int CodeDWord = *(unsigned int *)&CodeBytes[i]; 358 HexStream << format("%s%08X", (i > 0 ? " " : ""), CodeDWord); 359 } 360 361 DisasmStream.flush(); 362 DisasmLineMaxLen = std::max(DisasmLineMaxLen, DisasmLine.size()); 363 } 364 } 365 } 366 367 R600MCInstLower::R600MCInstLower(MCContext &Ctx, const R600Subtarget &ST, 368 const AsmPrinter &AP) : 369 AMDGPUMCInstLower(Ctx, ST, AP) { } 370 371 void R600MCInstLower::lower(const MachineInstr *MI, MCInst &OutMI) const { 372 OutMI.setOpcode(MI->getOpcode()); 373 for (const MachineOperand &MO : MI->explicit_operands()) { 374 MCOperand MCOp; 375 lowerOperand(MO, MCOp); 376 OutMI.addOperand(MCOp); 377 } 378 } 379 380 void R600AsmPrinter::EmitInstruction(const MachineInstr *MI) { 381 const R600Subtarget &STI = MF->getSubtarget<R600Subtarget>(); 382 R600MCInstLower MCInstLowering(OutContext, STI, *this); 383 384 StringRef Err; 385 if (!STI.getInstrInfo()->verifyInstruction(*MI, Err)) { 386 LLVMContext &C = MI->getParent()->getParent()->getFunction().getContext(); 387 C.emitError("Illegal instruction detected: " + Err); 388 MI->print(errs()); 389 } 390 391 if (MI->isBundle()) { 392 const MachineBasicBlock *MBB = MI->getParent(); 393 MachineBasicBlock::const_instr_iterator I = ++MI->getIterator(); 394 while (I != MBB->instr_end() && I->isInsideBundle()) { 395 EmitInstruction(&*I); 396 ++I; 397 } 398 } else { 399 MCInst TmpInst; 400 MCInstLowering.lower(MI, TmpInst); 401 EmitToStreamer(*OutStreamer, TmpInst); 402 } 403 } 404 405 const MCExpr *R600AsmPrinter::lowerConstant(const Constant *CV) { 406 if (const MCExpr *E = lowerAddrSpaceCast(TM, CV, OutContext)) 407 return E; 408 return AsmPrinter::lowerConstant(CV); 409 } 410