1 //===-- SIMCCodeEmitter.cpp - SI Code Emitter -----------------------------===// 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 /// The SI code emitter produces machine code that can be executed 11 /// directly on the GPU device. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "MCTargetDesc/AMDGPUFixupKinds.h" 16 #include "MCTargetDesc/AMDGPUMCCodeEmitter.h" 17 #include "MCTargetDesc/AMDGPUMCTargetDesc.h" 18 #include "SIDefines.h" 19 #include "Utils/AMDGPUBaseInfo.h" 20 #include "llvm/MC/MCContext.h" 21 #include "llvm/MC/MCExpr.h" 22 #include "llvm/MC/MCInstrInfo.h" 23 #include "llvm/MC/MCRegisterInfo.h" 24 25 using namespace llvm; 26 27 namespace { 28 29 class SIMCCodeEmitter : public AMDGPUMCCodeEmitter { 30 const MCRegisterInfo &MRI; 31 32 /// Encode an fp or int literal 33 uint32_t getLitEncoding(const MCOperand &MO, const MCOperandInfo &OpInfo, 34 const MCSubtargetInfo &STI) const; 35 36 public: 37 SIMCCodeEmitter(const MCInstrInfo &mcii, const MCRegisterInfo &mri, 38 MCContext &ctx) 39 : AMDGPUMCCodeEmitter(mcii), MRI(mri) {} 40 SIMCCodeEmitter(const SIMCCodeEmitter &) = delete; 41 SIMCCodeEmitter &operator=(const SIMCCodeEmitter &) = delete; 42 43 /// Encode the instruction and write it to the OS. 44 void encodeInstruction(const MCInst &MI, raw_ostream &OS, 45 SmallVectorImpl<MCFixup> &Fixups, 46 const MCSubtargetInfo &STI) const override; 47 48 /// \returns the encoding for an MCOperand. 49 uint64_t getMachineOpValue(const MCInst &MI, const MCOperand &MO, 50 SmallVectorImpl<MCFixup> &Fixups, 51 const MCSubtargetInfo &STI) const override; 52 53 /// Use a fixup to encode the simm16 field for SOPP branch 54 /// instructions. 55 unsigned getSOPPBrEncoding(const MCInst &MI, unsigned OpNo, 56 SmallVectorImpl<MCFixup> &Fixups, 57 const MCSubtargetInfo &STI) const override; 58 59 unsigned getSMEMOffsetEncoding(const MCInst &MI, unsigned OpNo, 60 SmallVectorImpl<MCFixup> &Fixups, 61 const MCSubtargetInfo &STI) const override; 62 63 unsigned getSDWASrcEncoding(const MCInst &MI, unsigned OpNo, 64 SmallVectorImpl<MCFixup> &Fixups, 65 const MCSubtargetInfo &STI) const override; 66 67 unsigned getSDWAVopcDstEncoding(const MCInst &MI, unsigned OpNo, 68 SmallVectorImpl<MCFixup> &Fixups, 69 const MCSubtargetInfo &STI) const override; 70 71 unsigned getAVOperandEncoding(const MCInst &MI, unsigned OpNo, 72 SmallVectorImpl<MCFixup> &Fixups, 73 const MCSubtargetInfo &STI) const override; 74 }; 75 76 } // end anonymous namespace 77 78 MCCodeEmitter *llvm::createSIMCCodeEmitter(const MCInstrInfo &MCII, 79 const MCRegisterInfo &MRI, 80 MCContext &Ctx) { 81 return new SIMCCodeEmitter(MCII, MRI, Ctx); 82 } 83 84 // Returns the encoding value to use if the given integer is an integer inline 85 // immediate value, or 0 if it is not. 86 template <typename IntTy> 87 static uint32_t getIntInlineImmEncoding(IntTy Imm) { 88 if (Imm >= 0 && Imm <= 64) 89 return 128 + Imm; 90 91 if (Imm >= -16 && Imm <= -1) 92 return 192 + std::abs(Imm); 93 94 return 0; 95 } 96 97 static uint32_t getLit16IntEncoding(uint16_t Val, const MCSubtargetInfo &STI) { 98 uint16_t IntImm = getIntInlineImmEncoding(static_cast<int16_t>(Val)); 99 return IntImm == 0 ? 255 : IntImm; 100 } 101 102 static uint32_t getLit16Encoding(uint16_t Val, const MCSubtargetInfo &STI) { 103 uint16_t IntImm = getIntInlineImmEncoding(static_cast<int16_t>(Val)); 104 if (IntImm != 0) 105 return IntImm; 106 107 if (Val == 0x3800) // 0.5 108 return 240; 109 110 if (Val == 0xB800) // -0.5 111 return 241; 112 113 if (Val == 0x3C00) // 1.0 114 return 242; 115 116 if (Val == 0xBC00) // -1.0 117 return 243; 118 119 if (Val == 0x4000) // 2.0 120 return 244; 121 122 if (Val == 0xC000) // -2.0 123 return 245; 124 125 if (Val == 0x4400) // 4.0 126 return 246; 127 128 if (Val == 0xC400) // -4.0 129 return 247; 130 131 if (Val == 0x3118 && // 1.0 / (2.0 * pi) 132 STI.getFeatureBits()[AMDGPU::FeatureInv2PiInlineImm]) 133 return 248; 134 135 return 255; 136 } 137 138 static uint32_t getLit32Encoding(uint32_t Val, const MCSubtargetInfo &STI) { 139 uint32_t IntImm = getIntInlineImmEncoding(static_cast<int32_t>(Val)); 140 if (IntImm != 0) 141 return IntImm; 142 143 if (Val == FloatToBits(0.5f)) 144 return 240; 145 146 if (Val == FloatToBits(-0.5f)) 147 return 241; 148 149 if (Val == FloatToBits(1.0f)) 150 return 242; 151 152 if (Val == FloatToBits(-1.0f)) 153 return 243; 154 155 if (Val == FloatToBits(2.0f)) 156 return 244; 157 158 if (Val == FloatToBits(-2.0f)) 159 return 245; 160 161 if (Val == FloatToBits(4.0f)) 162 return 246; 163 164 if (Val == FloatToBits(-4.0f)) 165 return 247; 166 167 if (Val == 0x3e22f983 && // 1.0 / (2.0 * pi) 168 STI.getFeatureBits()[AMDGPU::FeatureInv2PiInlineImm]) 169 return 248; 170 171 return 255; 172 } 173 174 static uint32_t getLit64Encoding(uint64_t Val, const MCSubtargetInfo &STI) { 175 uint32_t IntImm = getIntInlineImmEncoding(static_cast<int64_t>(Val)); 176 if (IntImm != 0) 177 return IntImm; 178 179 if (Val == DoubleToBits(0.5)) 180 return 240; 181 182 if (Val == DoubleToBits(-0.5)) 183 return 241; 184 185 if (Val == DoubleToBits(1.0)) 186 return 242; 187 188 if (Val == DoubleToBits(-1.0)) 189 return 243; 190 191 if (Val == DoubleToBits(2.0)) 192 return 244; 193 194 if (Val == DoubleToBits(-2.0)) 195 return 245; 196 197 if (Val == DoubleToBits(4.0)) 198 return 246; 199 200 if (Val == DoubleToBits(-4.0)) 201 return 247; 202 203 if (Val == 0x3fc45f306dc9c882 && // 1.0 / (2.0 * pi) 204 STI.getFeatureBits()[AMDGPU::FeatureInv2PiInlineImm]) 205 return 248; 206 207 return 255; 208 } 209 210 uint32_t SIMCCodeEmitter::getLitEncoding(const MCOperand &MO, 211 const MCOperandInfo &OpInfo, 212 const MCSubtargetInfo &STI) const { 213 int64_t Imm; 214 if (MO.isExpr()) { 215 const auto *C = dyn_cast<MCConstantExpr>(MO.getExpr()); 216 if (!C) 217 return 255; 218 219 Imm = C->getValue(); 220 } else { 221 222 assert(!MO.isDFPImm()); 223 224 if (!MO.isImm()) 225 return ~0; 226 227 Imm = MO.getImm(); 228 } 229 230 switch (OpInfo.OperandType) { 231 case AMDGPU::OPERAND_REG_IMM_INT32: 232 case AMDGPU::OPERAND_REG_IMM_FP32: 233 case AMDGPU::OPERAND_REG_INLINE_C_INT32: 234 case AMDGPU::OPERAND_REG_INLINE_C_FP32: 235 case AMDGPU::OPERAND_REG_INLINE_AC_INT32: 236 case AMDGPU::OPERAND_REG_INLINE_AC_FP32: 237 case AMDGPU::OPERAND_REG_IMM_V2INT32: 238 case AMDGPU::OPERAND_REG_IMM_V2FP32: 239 case AMDGPU::OPERAND_REG_INLINE_C_V2INT32: 240 case AMDGPU::OPERAND_REG_INLINE_C_V2FP32: 241 return getLit32Encoding(static_cast<uint32_t>(Imm), STI); 242 243 case AMDGPU::OPERAND_REG_IMM_INT64: 244 case AMDGPU::OPERAND_REG_IMM_FP64: 245 case AMDGPU::OPERAND_REG_INLINE_C_INT64: 246 case AMDGPU::OPERAND_REG_INLINE_C_FP64: 247 case AMDGPU::OPERAND_REG_INLINE_AC_FP64: 248 return getLit64Encoding(static_cast<uint64_t>(Imm), STI); 249 250 case AMDGPU::OPERAND_REG_IMM_INT16: 251 case AMDGPU::OPERAND_REG_INLINE_C_INT16: 252 case AMDGPU::OPERAND_REG_INLINE_AC_INT16: 253 return getLit16IntEncoding(static_cast<uint16_t>(Imm), STI); 254 case AMDGPU::OPERAND_REG_IMM_FP16: 255 case AMDGPU::OPERAND_REG_INLINE_C_FP16: 256 case AMDGPU::OPERAND_REG_INLINE_AC_FP16: 257 // FIXME Is this correct? What do inline immediates do on SI for f16 src 258 // which does not have f16 support? 259 return getLit16Encoding(static_cast<uint16_t>(Imm), STI); 260 case AMDGPU::OPERAND_REG_IMM_V2INT16: 261 case AMDGPU::OPERAND_REG_IMM_V2FP16: { 262 if (!isUInt<16>(Imm) && STI.getFeatureBits()[AMDGPU::FeatureVOP3Literal]) 263 return getLit32Encoding(static_cast<uint32_t>(Imm), STI); 264 if (OpInfo.OperandType == AMDGPU::OPERAND_REG_IMM_V2FP16) 265 return getLit16Encoding(static_cast<uint16_t>(Imm), STI); 266 LLVM_FALLTHROUGH; 267 } 268 case AMDGPU::OPERAND_REG_INLINE_C_V2INT16: 269 case AMDGPU::OPERAND_REG_INLINE_AC_V2INT16: 270 return getLit16IntEncoding(static_cast<uint16_t>(Imm), STI); 271 case AMDGPU::OPERAND_REG_INLINE_C_V2FP16: 272 case AMDGPU::OPERAND_REG_INLINE_AC_V2FP16: { 273 uint16_t Lo16 = static_cast<uint16_t>(Imm); 274 uint32_t Encoding = getLit16Encoding(Lo16, STI); 275 return Encoding; 276 } 277 default: 278 llvm_unreachable("invalid operand size"); 279 } 280 } 281 282 void SIMCCodeEmitter::encodeInstruction(const MCInst &MI, raw_ostream &OS, 283 SmallVectorImpl<MCFixup> &Fixups, 284 const MCSubtargetInfo &STI) const { 285 verifyInstructionPredicates(MI, 286 computeAvailableFeatures(STI.getFeatureBits())); 287 288 uint64_t Encoding = getBinaryCodeForInstr(MI, Fixups, STI); 289 const MCInstrDesc &Desc = MCII.get(MI.getOpcode()); 290 unsigned bytes = Desc.getSize(); 291 292 switch (MI.getOpcode()) { 293 case AMDGPU::V_ACCVGPR_READ_B32_vi: 294 case AMDGPU::V_ACCVGPR_WRITE_B32_vi: 295 // Set unused op_sel_hi bits to 1. 296 // FIXME: This shall be done for all VOP3P but not MAI instructions with 297 // unused op_sel_hi bits if corresponding operands do not exist. 298 // accvgpr_read/write are different, however. These are VOP3P, MAI, have 299 // src0, but do not use op_sel. 300 Encoding |= (1ull << 14) | (1ull << 59) | (1ull << 60); 301 break; 302 default: 303 break; 304 } 305 306 for (unsigned i = 0; i < bytes; i++) { 307 OS.write((uint8_t) ((Encoding >> (8 * i)) & 0xff)); 308 } 309 310 // NSA encoding. 311 if (AMDGPU::isGFX10Plus(STI) && Desc.TSFlags & SIInstrFlags::MIMG) { 312 int vaddr0 = AMDGPU::getNamedOperandIdx(MI.getOpcode(), 313 AMDGPU::OpName::vaddr0); 314 int srsrc = AMDGPU::getNamedOperandIdx(MI.getOpcode(), 315 AMDGPU::OpName::srsrc); 316 assert(vaddr0 >= 0 && srsrc > vaddr0); 317 unsigned NumExtraAddrs = srsrc - vaddr0 - 1; 318 unsigned NumPadding = (-NumExtraAddrs) & 3; 319 320 for (unsigned i = 0; i < NumExtraAddrs; ++i) 321 OS.write((uint8_t)getMachineOpValue(MI, MI.getOperand(vaddr0 + 1 + i), 322 Fixups, STI)); 323 for (unsigned i = 0; i < NumPadding; ++i) 324 OS.write(0); 325 } 326 327 if ((bytes > 8 && STI.getFeatureBits()[AMDGPU::FeatureVOP3Literal]) || 328 (bytes > 4 && !STI.getFeatureBits()[AMDGPU::FeatureVOP3Literal])) 329 return; 330 331 // Check for additional literals in SRC0/1/2 (Op 1/2/3) 332 for (unsigned i = 0, e = Desc.getNumOperands(); i < e; ++i) { 333 334 // Check if this operand should be encoded as [SV]Src 335 if (!AMDGPU::isSISrcOperand(Desc, i)) 336 continue; 337 338 // Is this operand a literal immediate? 339 const MCOperand &Op = MI.getOperand(i); 340 if (getLitEncoding(Op, Desc.OpInfo[i], STI) != 255) 341 continue; 342 343 // Yes! Encode it 344 int64_t Imm = 0; 345 346 if (Op.isImm()) 347 Imm = Op.getImm(); 348 else if (Op.isExpr()) { 349 if (const auto *C = dyn_cast<MCConstantExpr>(Op.getExpr())) 350 Imm = C->getValue(); 351 352 } else if (!Op.isExpr()) // Exprs will be replaced with a fixup value. 353 llvm_unreachable("Must be immediate or expr"); 354 355 for (unsigned j = 0; j < 4; j++) { 356 OS.write((uint8_t) ((Imm >> (8 * j)) & 0xff)); 357 } 358 359 // Only one literal value allowed 360 break; 361 } 362 } 363 364 unsigned SIMCCodeEmitter::getSOPPBrEncoding(const MCInst &MI, unsigned OpNo, 365 SmallVectorImpl<MCFixup> &Fixups, 366 const MCSubtargetInfo &STI) const { 367 const MCOperand &MO = MI.getOperand(OpNo); 368 369 if (MO.isExpr()) { 370 const MCExpr *Expr = MO.getExpr(); 371 MCFixupKind Kind = (MCFixupKind)AMDGPU::fixup_si_sopp_br; 372 Fixups.push_back(MCFixup::create(0, Expr, Kind, MI.getLoc())); 373 return 0; 374 } 375 376 return getMachineOpValue(MI, MO, Fixups, STI); 377 } 378 379 unsigned SIMCCodeEmitter::getSMEMOffsetEncoding(const MCInst &MI, unsigned OpNo, 380 SmallVectorImpl<MCFixup> &Fixups, 381 const MCSubtargetInfo &STI) const { 382 auto Offset = MI.getOperand(OpNo).getImm(); 383 // VI only supports 20-bit unsigned offsets. 384 assert(!AMDGPU::isVI(STI) || isUInt<20>(Offset)); 385 return Offset; 386 } 387 388 unsigned 389 SIMCCodeEmitter::getSDWASrcEncoding(const MCInst &MI, unsigned OpNo, 390 SmallVectorImpl<MCFixup> &Fixups, 391 const MCSubtargetInfo &STI) const { 392 using namespace AMDGPU::SDWA; 393 394 uint64_t RegEnc = 0; 395 396 const MCOperand &MO = MI.getOperand(OpNo); 397 398 if (MO.isReg()) { 399 unsigned Reg = MO.getReg(); 400 RegEnc |= MRI.getEncodingValue(Reg); 401 RegEnc &= SDWA9EncValues::SRC_VGPR_MASK; 402 if (AMDGPU::isSGPR(AMDGPU::mc2PseudoReg(Reg), &MRI)) { 403 RegEnc |= SDWA9EncValues::SRC_SGPR_MASK; 404 } 405 return RegEnc; 406 } else { 407 const MCInstrDesc &Desc = MCII.get(MI.getOpcode()); 408 uint32_t Enc = getLitEncoding(MO, Desc.OpInfo[OpNo], STI); 409 if (Enc != ~0U && Enc != 255) { 410 return Enc | SDWA9EncValues::SRC_SGPR_MASK; 411 } 412 } 413 414 llvm_unreachable("Unsupported operand kind"); 415 return 0; 416 } 417 418 unsigned 419 SIMCCodeEmitter::getSDWAVopcDstEncoding(const MCInst &MI, unsigned OpNo, 420 SmallVectorImpl<MCFixup> &Fixups, 421 const MCSubtargetInfo &STI) const { 422 using namespace AMDGPU::SDWA; 423 424 uint64_t RegEnc = 0; 425 426 const MCOperand &MO = MI.getOperand(OpNo); 427 428 unsigned Reg = MO.getReg(); 429 if (Reg != AMDGPU::VCC && Reg != AMDGPU::VCC_LO) { 430 RegEnc |= MRI.getEncodingValue(Reg); 431 RegEnc &= SDWA9EncValues::VOPC_DST_SGPR_MASK; 432 RegEnc |= SDWA9EncValues::VOPC_DST_VCC_MASK; 433 } 434 return RegEnc; 435 } 436 437 unsigned 438 SIMCCodeEmitter::getAVOperandEncoding(const MCInst &MI, unsigned OpNo, 439 SmallVectorImpl<MCFixup> &Fixups, 440 const MCSubtargetInfo &STI) const { 441 unsigned Reg = MI.getOperand(OpNo).getReg(); 442 uint64_t Enc = MRI.getEncodingValue(Reg); 443 444 // VGPR and AGPR have the same encoding, but SrcA and SrcB operands of mfma 445 // instructions use acc[0:1] modifier bits to distinguish. These bits are 446 // encoded as a virtual 9th bit of the register for these operands. 447 if (MRI.getRegClass(AMDGPU::AGPR_32RegClassID).contains(Reg) || 448 MRI.getRegClass(AMDGPU::AReg_64RegClassID).contains(Reg) || 449 MRI.getRegClass(AMDGPU::AReg_96RegClassID).contains(Reg) || 450 MRI.getRegClass(AMDGPU::AReg_128RegClassID).contains(Reg) || 451 MRI.getRegClass(AMDGPU::AReg_160RegClassID).contains(Reg) || 452 MRI.getRegClass(AMDGPU::AReg_192RegClassID).contains(Reg) || 453 MRI.getRegClass(AMDGPU::AReg_256RegClassID).contains(Reg) || 454 MRI.getRegClass(AMDGPU::AGPR_LO16RegClassID).contains(Reg)) 455 Enc |= 512; 456 457 return Enc; 458 } 459 460 static bool needsPCRel(const MCExpr *Expr) { 461 switch (Expr->getKind()) { 462 case MCExpr::SymbolRef: { 463 auto *SE = cast<MCSymbolRefExpr>(Expr); 464 MCSymbolRefExpr::VariantKind Kind = SE->getKind(); 465 return Kind != MCSymbolRefExpr::VK_AMDGPU_ABS32_LO && 466 Kind != MCSymbolRefExpr::VK_AMDGPU_ABS32_HI; 467 } 468 case MCExpr::Binary: { 469 auto *BE = cast<MCBinaryExpr>(Expr); 470 if (BE->getOpcode() == MCBinaryExpr::Sub) 471 return false; 472 return needsPCRel(BE->getLHS()) || needsPCRel(BE->getRHS()); 473 } 474 case MCExpr::Unary: 475 return needsPCRel(cast<MCUnaryExpr>(Expr)->getSubExpr()); 476 case MCExpr::Target: 477 case MCExpr::Constant: 478 return false; 479 } 480 llvm_unreachable("invalid kind"); 481 } 482 483 uint64_t SIMCCodeEmitter::getMachineOpValue(const MCInst &MI, 484 const MCOperand &MO, 485 SmallVectorImpl<MCFixup> &Fixups, 486 const MCSubtargetInfo &STI) const { 487 if (MO.isReg()) 488 return MRI.getEncodingValue(MO.getReg()); 489 490 if (MO.isExpr() && MO.getExpr()->getKind() != MCExpr::Constant) { 491 // FIXME: If this is expression is PCRel or not should not depend on what 492 // the expression looks like. Given that this is just a general expression, 493 // it should probably be FK_Data_4 and whatever is producing 494 // 495 // s_add_u32 s2, s2, (extern_const_addrspace+16 496 // 497 // And expecting a PCRel should instead produce 498 // 499 // .Ltmp1: 500 // s_add_u32 s2, s2, (extern_const_addrspace+16)-.Ltmp1 501 MCFixupKind Kind; 502 if (needsPCRel(MO.getExpr())) 503 Kind = FK_PCRel_4; 504 else 505 Kind = FK_Data_4; 506 507 const MCInstrDesc &Desc = MCII.get(MI.getOpcode()); 508 uint32_t Offset = Desc.getSize(); 509 assert(Offset == 4 || Offset == 8); 510 511 Fixups.push_back( 512 MCFixup::create(Offset, MO.getExpr(), Kind, MI.getLoc())); 513 } 514 515 // Figure out the operand number, needed for isSrcOperand check 516 unsigned OpNo = 0; 517 for (unsigned e = MI.getNumOperands(); OpNo < e; ++OpNo) { 518 if (&MO == &MI.getOperand(OpNo)) 519 break; 520 } 521 522 const MCInstrDesc &Desc = MCII.get(MI.getOpcode()); 523 if (AMDGPU::isSISrcOperand(Desc, OpNo)) { 524 uint32_t Enc = getLitEncoding(MO, Desc.OpInfo[OpNo], STI); 525 if (Enc != ~0U && 526 (Enc != 255 || Desc.getSize() == 4 || Desc.getSize() == 8)) 527 return Enc; 528 529 } else if (MO.isImm()) 530 return MO.getImm(); 531 532 llvm_unreachable("Encoding of this operand type is not supported yet."); 533 return 0; 534 } 535 536 #define ENABLE_INSTR_PREDICATE_VERIFIER 537 #include "AMDGPUGenMCCodeEmitter.inc" 538