1 //===-- X86/X86CodeEmitter.cpp - Convert X86 code to machine code ---------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file contains the pass that transforms the X86 machine instructions into 11 // relocatable machine code. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #define DEBUG_TYPE "x86-emitter" 16 #include "X86InstrInfo.h" 17 #include "X86JITInfo.h" 18 #include "X86Subtarget.h" 19 #include "X86TargetMachine.h" 20 #include "X86Relocations.h" 21 #include "X86.h" 22 #include "llvm/LLVMContext.h" 23 #include "llvm/PassManager.h" 24 #include "llvm/CodeGen/JITCodeEmitter.h" 25 #include "llvm/CodeGen/MachineFunctionPass.h" 26 #include "llvm/CodeGen/MachineInstr.h" 27 #include "llvm/CodeGen/MachineModuleInfo.h" 28 #include "llvm/CodeGen/Passes.h" 29 #include "llvm/Function.h" 30 #include "llvm/ADT/Statistic.h" 31 #include "llvm/MC/MCCodeEmitter.h" 32 #include "llvm/MC/MCExpr.h" 33 #include "llvm/MC/MCInst.h" 34 #include "llvm/Support/Debug.h" 35 #include "llvm/Support/ErrorHandling.h" 36 #include "llvm/Support/raw_ostream.h" 37 #include "llvm/Target/TargetOptions.h" 38 using namespace llvm; 39 40 STATISTIC(NumEmitted, "Number of machine instructions emitted"); 41 42 namespace { 43 template<class CodeEmitter> 44 class Emitter : public MachineFunctionPass { 45 const X86InstrInfo *II; 46 const TargetData *TD; 47 X86TargetMachine &TM; 48 CodeEmitter &MCE; 49 MachineModuleInfo *MMI; 50 intptr_t PICBaseOffset; 51 bool Is64BitMode; 52 bool IsPIC; 53 public: 54 static char ID; 55 explicit Emitter(X86TargetMachine &tm, CodeEmitter &mce) 56 : MachineFunctionPass(ID), II(0), TD(0), TM(tm), 57 MCE(mce), PICBaseOffset(0), Is64BitMode(false), 58 IsPIC(TM.getRelocationModel() == Reloc::PIC_) {} 59 Emitter(X86TargetMachine &tm, CodeEmitter &mce, 60 const X86InstrInfo &ii, const TargetData &td, bool is64) 61 : MachineFunctionPass(ID), II(&ii), TD(&td), TM(tm), 62 MCE(mce), PICBaseOffset(0), Is64BitMode(is64), 63 IsPIC(TM.getRelocationModel() == Reloc::PIC_) {} 64 65 bool runOnMachineFunction(MachineFunction &MF); 66 67 virtual const char *getPassName() const { 68 return "X86 Machine Code Emitter"; 69 } 70 71 void emitInstruction(MachineInstr &MI, const MCInstrDesc *Desc); 72 73 void getAnalysisUsage(AnalysisUsage &AU) const { 74 AU.setPreservesAll(); 75 AU.addRequired<MachineModuleInfo>(); 76 MachineFunctionPass::getAnalysisUsage(AU); 77 } 78 79 private: 80 void emitPCRelativeBlockAddress(MachineBasicBlock *MBB); 81 void emitGlobalAddress(const GlobalValue *GV, unsigned Reloc, 82 intptr_t Disp = 0, intptr_t PCAdj = 0, 83 bool Indirect = false); 84 void emitExternalSymbolAddress(const char *ES, unsigned Reloc); 85 void emitConstPoolAddress(unsigned CPI, unsigned Reloc, intptr_t Disp = 0, 86 intptr_t PCAdj = 0); 87 void emitJumpTableAddress(unsigned JTI, unsigned Reloc, 88 intptr_t PCAdj = 0); 89 90 void emitDisplacementField(const MachineOperand *RelocOp, int DispVal, 91 intptr_t Adj = 0, bool IsPCRel = true); 92 93 void emitRegModRMByte(unsigned ModRMReg, unsigned RegOpcodeField); 94 void emitRegModRMByte(unsigned RegOpcodeField); 95 void emitSIBByte(unsigned SS, unsigned Index, unsigned Base); 96 void emitConstant(uint64_t Val, unsigned Size); 97 98 void emitMemModRMByte(const MachineInstr &MI, 99 unsigned Op, unsigned RegOpcodeField, 100 intptr_t PCAdj = 0); 101 }; 102 103 template<class CodeEmitter> 104 char Emitter<CodeEmitter>::ID = 0; 105 } // end anonymous namespace. 106 107 /// createX86CodeEmitterPass - Return a pass that emits the collected X86 code 108 /// to the specified templated MachineCodeEmitter object. 109 FunctionPass *llvm::createX86JITCodeEmitterPass(X86TargetMachine &TM, 110 JITCodeEmitter &JCE) { 111 return new Emitter<JITCodeEmitter>(TM, JCE); 112 } 113 114 template<class CodeEmitter> 115 bool Emitter<CodeEmitter>::runOnMachineFunction(MachineFunction &MF) { 116 MMI = &getAnalysis<MachineModuleInfo>(); 117 MCE.setModuleInfo(MMI); 118 119 II = TM.getInstrInfo(); 120 TD = TM.getTargetData(); 121 Is64BitMode = TM.getSubtarget<X86Subtarget>().is64Bit(); 122 IsPIC = TM.getRelocationModel() == Reloc::PIC_; 123 124 do { 125 DEBUG(dbgs() << "JITTing function '" 126 << MF.getFunction()->getName() << "'\n"); 127 MCE.startFunction(MF); 128 for (MachineFunction::iterator MBB = MF.begin(), E = MF.end(); 129 MBB != E; ++MBB) { 130 MCE.StartMachineBasicBlock(MBB); 131 for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); 132 I != E; ++I) { 133 const MCInstrDesc &Desc = I->getDesc(); 134 emitInstruction(*I, &Desc); 135 // MOVPC32r is basically a call plus a pop instruction. 136 if (Desc.getOpcode() == X86::MOVPC32r) 137 emitInstruction(*I, &II->get(X86::POP32r)); 138 ++NumEmitted; // Keep track of the # of mi's emitted 139 } 140 } 141 } while (MCE.finishFunction(MF)); 142 143 return false; 144 } 145 146 /// determineREX - Determine if the MachineInstr has to be encoded with a X86-64 147 /// REX prefix which specifies 1) 64-bit instructions, 2) non-default operand 148 /// size, and 3) use of X86-64 extended registers. 149 static unsigned determineREX(const MachineInstr &MI) { 150 unsigned REX = 0; 151 const MCInstrDesc &Desc = MI.getDesc(); 152 153 // Pseudo instructions do not need REX prefix byte. 154 if ((Desc.TSFlags & X86II::FormMask) == X86II::Pseudo) 155 return 0; 156 if (Desc.TSFlags & X86II::REX_W) 157 REX |= 1 << 3; 158 159 unsigned NumOps = Desc.getNumOperands(); 160 if (NumOps) { 161 bool isTwoAddr = NumOps > 1 && 162 Desc.getOperandConstraint(1, MCOI::TIED_TO) != -1; 163 164 // If it accesses SPL, BPL, SIL, or DIL, then it requires a 0x40 REX prefix. 165 unsigned i = isTwoAddr ? 1 : 0; 166 for (unsigned e = NumOps; i != e; ++i) { 167 const MachineOperand& MO = MI.getOperand(i); 168 if (MO.isReg()) { 169 unsigned Reg = MO.getReg(); 170 if (X86II::isX86_64NonExtLowByteReg(Reg)) 171 REX |= 0x40; 172 } 173 } 174 175 switch (Desc.TSFlags & X86II::FormMask) { 176 case X86II::MRMInitReg: 177 if (X86InstrInfo::isX86_64ExtendedReg(MI.getOperand(0))) 178 REX |= (1 << 0) | (1 << 2); 179 break; 180 case X86II::MRMSrcReg: { 181 if (X86InstrInfo::isX86_64ExtendedReg(MI.getOperand(0))) 182 REX |= 1 << 2; 183 i = isTwoAddr ? 2 : 1; 184 for (unsigned e = NumOps; i != e; ++i) { 185 const MachineOperand& MO = MI.getOperand(i); 186 if (X86InstrInfo::isX86_64ExtendedReg(MO)) 187 REX |= 1 << 0; 188 } 189 break; 190 } 191 case X86II::MRMSrcMem: { 192 if (X86InstrInfo::isX86_64ExtendedReg(MI.getOperand(0))) 193 REX |= 1 << 2; 194 unsigned Bit = 0; 195 i = isTwoAddr ? 2 : 1; 196 for (; i != NumOps; ++i) { 197 const MachineOperand& MO = MI.getOperand(i); 198 if (MO.isReg()) { 199 if (X86InstrInfo::isX86_64ExtendedReg(MO)) 200 REX |= 1 << Bit; 201 Bit++; 202 } 203 } 204 break; 205 } 206 case X86II::MRM0m: case X86II::MRM1m: 207 case X86II::MRM2m: case X86II::MRM3m: 208 case X86II::MRM4m: case X86II::MRM5m: 209 case X86II::MRM6m: case X86II::MRM7m: 210 case X86II::MRMDestMem: { 211 unsigned e = (isTwoAddr ? X86::AddrNumOperands+1 : X86::AddrNumOperands); 212 i = isTwoAddr ? 1 : 0; 213 if (NumOps > e && X86InstrInfo::isX86_64ExtendedReg(MI.getOperand(e))) 214 REX |= 1 << 2; 215 unsigned Bit = 0; 216 for (; i != e; ++i) { 217 const MachineOperand& MO = MI.getOperand(i); 218 if (MO.isReg()) { 219 if (X86InstrInfo::isX86_64ExtendedReg(MO)) 220 REX |= 1 << Bit; 221 Bit++; 222 } 223 } 224 break; 225 } 226 default: { 227 if (X86InstrInfo::isX86_64ExtendedReg(MI.getOperand(0))) 228 REX |= 1 << 0; 229 i = isTwoAddr ? 2 : 1; 230 for (unsigned e = NumOps; i != e; ++i) { 231 const MachineOperand& MO = MI.getOperand(i); 232 if (X86InstrInfo::isX86_64ExtendedReg(MO)) 233 REX |= 1 << 2; 234 } 235 break; 236 } 237 } 238 } 239 return REX; 240 } 241 242 243 /// emitPCRelativeBlockAddress - This method keeps track of the information 244 /// necessary to resolve the address of this block later and emits a dummy 245 /// value. 246 /// 247 template<class CodeEmitter> 248 void Emitter<CodeEmitter>::emitPCRelativeBlockAddress(MachineBasicBlock *MBB) { 249 // Remember where this reference was and where it is to so we can 250 // deal with it later. 251 MCE.addRelocation(MachineRelocation::getBB(MCE.getCurrentPCOffset(), 252 X86::reloc_pcrel_word, MBB)); 253 MCE.emitWordLE(0); 254 } 255 256 /// emitGlobalAddress - Emit the specified address to the code stream assuming 257 /// this is part of a "take the address of a global" instruction. 258 /// 259 template<class CodeEmitter> 260 void Emitter<CodeEmitter>::emitGlobalAddress(const GlobalValue *GV, 261 unsigned Reloc, 262 intptr_t Disp /* = 0 */, 263 intptr_t PCAdj /* = 0 */, 264 bool Indirect /* = false */) { 265 intptr_t RelocCST = Disp; 266 if (Reloc == X86::reloc_picrel_word) 267 RelocCST = PICBaseOffset; 268 else if (Reloc == X86::reloc_pcrel_word) 269 RelocCST = PCAdj; 270 MachineRelocation MR = Indirect 271 ? MachineRelocation::getIndirectSymbol(MCE.getCurrentPCOffset(), Reloc, 272 const_cast<GlobalValue *>(GV), 273 RelocCST, false) 274 : MachineRelocation::getGV(MCE.getCurrentPCOffset(), Reloc, 275 const_cast<GlobalValue *>(GV), RelocCST, false); 276 MCE.addRelocation(MR); 277 // The relocated value will be added to the displacement 278 if (Reloc == X86::reloc_absolute_dword) 279 MCE.emitDWordLE(Disp); 280 else 281 MCE.emitWordLE((int32_t)Disp); 282 } 283 284 /// emitExternalSymbolAddress - Arrange for the address of an external symbol to 285 /// be emitted to the current location in the function, and allow it to be PC 286 /// relative. 287 template<class CodeEmitter> 288 void Emitter<CodeEmitter>::emitExternalSymbolAddress(const char *ES, 289 unsigned Reloc) { 290 intptr_t RelocCST = (Reloc == X86::reloc_picrel_word) ? PICBaseOffset : 0; 291 292 // X86 never needs stubs because instruction selection will always pick 293 // an instruction sequence that is large enough to hold any address 294 // to a symbol. 295 // (see X86ISelLowering.cpp, near 2039: X86TargetLowering::LowerCall) 296 bool NeedStub = false; 297 MCE.addRelocation(MachineRelocation::getExtSym(MCE.getCurrentPCOffset(), 298 Reloc, ES, RelocCST, 299 0, NeedStub)); 300 if (Reloc == X86::reloc_absolute_dword) 301 MCE.emitDWordLE(0); 302 else 303 MCE.emitWordLE(0); 304 } 305 306 /// emitConstPoolAddress - Arrange for the address of an constant pool 307 /// to be emitted to the current location in the function, and allow it to be PC 308 /// relative. 309 template<class CodeEmitter> 310 void Emitter<CodeEmitter>::emitConstPoolAddress(unsigned CPI, unsigned Reloc, 311 intptr_t Disp /* = 0 */, 312 intptr_t PCAdj /* = 0 */) { 313 intptr_t RelocCST = 0; 314 if (Reloc == X86::reloc_picrel_word) 315 RelocCST = PICBaseOffset; 316 else if (Reloc == X86::reloc_pcrel_word) 317 RelocCST = PCAdj; 318 MCE.addRelocation(MachineRelocation::getConstPool(MCE.getCurrentPCOffset(), 319 Reloc, CPI, RelocCST)); 320 // The relocated value will be added to the displacement 321 if (Reloc == X86::reloc_absolute_dword) 322 MCE.emitDWordLE(Disp); 323 else 324 MCE.emitWordLE((int32_t)Disp); 325 } 326 327 /// emitJumpTableAddress - Arrange for the address of a jump table to 328 /// be emitted to the current location in the function, and allow it to be PC 329 /// relative. 330 template<class CodeEmitter> 331 void Emitter<CodeEmitter>::emitJumpTableAddress(unsigned JTI, unsigned Reloc, 332 intptr_t PCAdj /* = 0 */) { 333 intptr_t RelocCST = 0; 334 if (Reloc == X86::reloc_picrel_word) 335 RelocCST = PICBaseOffset; 336 else if (Reloc == X86::reloc_pcrel_word) 337 RelocCST = PCAdj; 338 MCE.addRelocation(MachineRelocation::getJumpTable(MCE.getCurrentPCOffset(), 339 Reloc, JTI, RelocCST)); 340 // The relocated value will be added to the displacement 341 if (Reloc == X86::reloc_absolute_dword) 342 MCE.emitDWordLE(0); 343 else 344 MCE.emitWordLE(0); 345 } 346 347 inline static unsigned char ModRMByte(unsigned Mod, unsigned RegOpcode, 348 unsigned RM) { 349 assert(Mod < 4 && RegOpcode < 8 && RM < 8 && "ModRM Fields out of range!"); 350 return RM | (RegOpcode << 3) | (Mod << 6); 351 } 352 353 template<class CodeEmitter> 354 void Emitter<CodeEmitter>::emitRegModRMByte(unsigned ModRMReg, 355 unsigned RegOpcodeFld){ 356 MCE.emitByte(ModRMByte(3, RegOpcodeFld, X86_MC::getX86RegNum(ModRMReg))); 357 } 358 359 template<class CodeEmitter> 360 void Emitter<CodeEmitter>::emitRegModRMByte(unsigned RegOpcodeFld) { 361 MCE.emitByte(ModRMByte(3, RegOpcodeFld, 0)); 362 } 363 364 template<class CodeEmitter> 365 void Emitter<CodeEmitter>::emitSIBByte(unsigned SS, 366 unsigned Index, 367 unsigned Base) { 368 // SIB byte is in the same format as the ModRMByte... 369 MCE.emitByte(ModRMByte(SS, Index, Base)); 370 } 371 372 template<class CodeEmitter> 373 void Emitter<CodeEmitter>::emitConstant(uint64_t Val, unsigned Size) { 374 // Output the constant in little endian byte order... 375 for (unsigned i = 0; i != Size; ++i) { 376 MCE.emitByte(Val & 255); 377 Val >>= 8; 378 } 379 } 380 381 /// isDisp8 - Return true if this signed displacement fits in a 8-bit 382 /// sign-extended field. 383 static bool isDisp8(int Value) { 384 return Value == (signed char)Value; 385 } 386 387 static bool gvNeedsNonLazyPtr(const MachineOperand &GVOp, 388 const TargetMachine &TM) { 389 // For Darwin-64, simulate the linktime GOT by using the same non-lazy-pointer 390 // mechanism as 32-bit mode. 391 if (TM.getSubtarget<X86Subtarget>().is64Bit() && 392 !TM.getSubtarget<X86Subtarget>().isTargetDarwin()) 393 return false; 394 395 // Return true if this is a reference to a stub containing the address of the 396 // global, not the global itself. 397 return isGlobalStubReference(GVOp.getTargetFlags()); 398 } 399 400 template<class CodeEmitter> 401 void Emitter<CodeEmitter>::emitDisplacementField(const MachineOperand *RelocOp, 402 int DispVal, 403 intptr_t Adj /* = 0 */, 404 bool IsPCRel /* = true */) { 405 // If this is a simple integer displacement that doesn't require a relocation, 406 // emit it now. 407 if (!RelocOp) { 408 emitConstant(DispVal, 4); 409 return; 410 } 411 412 // Otherwise, this is something that requires a relocation. Emit it as such 413 // now. 414 unsigned RelocType = Is64BitMode ? 415 (IsPCRel ? X86::reloc_pcrel_word : X86::reloc_absolute_word_sext) 416 : (IsPIC ? X86::reloc_picrel_word : X86::reloc_absolute_word); 417 if (RelocOp->isGlobal()) { 418 // In 64-bit static small code model, we could potentially emit absolute. 419 // But it's probably not beneficial. If the MCE supports using RIP directly 420 // do it, otherwise fallback to absolute (this is determined by IsPCRel). 421 // 89 05 00 00 00 00 mov %eax,0(%rip) # PC-relative 422 // 89 04 25 00 00 00 00 mov %eax,0x0 # Absolute 423 bool Indirect = gvNeedsNonLazyPtr(*RelocOp, TM); 424 emitGlobalAddress(RelocOp->getGlobal(), RelocType, RelocOp->getOffset(), 425 Adj, Indirect); 426 } else if (RelocOp->isSymbol()) { 427 emitExternalSymbolAddress(RelocOp->getSymbolName(), RelocType); 428 } else if (RelocOp->isCPI()) { 429 emitConstPoolAddress(RelocOp->getIndex(), RelocType, 430 RelocOp->getOffset(), Adj); 431 } else { 432 assert(RelocOp->isJTI() && "Unexpected machine operand!"); 433 emitJumpTableAddress(RelocOp->getIndex(), RelocType, Adj); 434 } 435 } 436 437 template<class CodeEmitter> 438 void Emitter<CodeEmitter>::emitMemModRMByte(const MachineInstr &MI, 439 unsigned Op,unsigned RegOpcodeField, 440 intptr_t PCAdj) { 441 const MachineOperand &Op3 = MI.getOperand(Op+3); 442 int DispVal = 0; 443 const MachineOperand *DispForReloc = 0; 444 445 // Figure out what sort of displacement we have to handle here. 446 if (Op3.isGlobal()) { 447 DispForReloc = &Op3; 448 } else if (Op3.isSymbol()) { 449 DispForReloc = &Op3; 450 } else if (Op3.isCPI()) { 451 if (!MCE.earlyResolveAddresses() || Is64BitMode || IsPIC) { 452 DispForReloc = &Op3; 453 } else { 454 DispVal += MCE.getConstantPoolEntryAddress(Op3.getIndex()); 455 DispVal += Op3.getOffset(); 456 } 457 } else if (Op3.isJTI()) { 458 if (!MCE.earlyResolveAddresses() || Is64BitMode || IsPIC) { 459 DispForReloc = &Op3; 460 } else { 461 DispVal += MCE.getJumpTableEntryAddress(Op3.getIndex()); 462 } 463 } else { 464 DispVal = Op3.getImm(); 465 } 466 467 const MachineOperand &Base = MI.getOperand(Op); 468 const MachineOperand &Scale = MI.getOperand(Op+1); 469 const MachineOperand &IndexReg = MI.getOperand(Op+2); 470 471 unsigned BaseReg = Base.getReg(); 472 473 // Handle %rip relative addressing. 474 if (BaseReg == X86::RIP || 475 (Is64BitMode && DispForReloc)) { // [disp32+RIP] in X86-64 mode 476 assert(IndexReg.getReg() == 0 && Is64BitMode && 477 "Invalid rip-relative address"); 478 MCE.emitByte(ModRMByte(0, RegOpcodeField, 5)); 479 emitDisplacementField(DispForReloc, DispVal, PCAdj, true); 480 return; 481 } 482 483 // Indicate that the displacement will use an pcrel or absolute reference 484 // by default. MCEs able to resolve addresses on-the-fly use pcrel by default 485 // while others, unless explicit asked to use RIP, use absolute references. 486 bool IsPCRel = MCE.earlyResolveAddresses() ? true : false; 487 488 // Is a SIB byte needed? 489 // If no BaseReg, issue a RIP relative instruction only if the MCE can 490 // resolve addresses on-the-fly, otherwise use SIB (Intel Manual 2A, table 491 // 2-7) and absolute references. 492 unsigned BaseRegNo = -1U; 493 if (BaseReg != 0 && BaseReg != X86::RIP) 494 BaseRegNo = X86_MC::getX86RegNum(BaseReg); 495 496 if (// The SIB byte must be used if there is an index register. 497 IndexReg.getReg() == 0 && 498 // The SIB byte must be used if the base is ESP/RSP/R12, all of which 499 // encode to an R/M value of 4, which indicates that a SIB byte is 500 // present. 501 BaseRegNo != N86::ESP && 502 // If there is no base register and we're in 64-bit mode, we need a SIB 503 // byte to emit an addr that is just 'disp32' (the non-RIP relative form). 504 (!Is64BitMode || BaseReg != 0)) { 505 if (BaseReg == 0 || // [disp32] in X86-32 mode 506 BaseReg == X86::RIP) { // [disp32+RIP] in X86-64 mode 507 MCE.emitByte(ModRMByte(0, RegOpcodeField, 5)); 508 emitDisplacementField(DispForReloc, DispVal, PCAdj, true); 509 return; 510 } 511 512 // If the base is not EBP/ESP and there is no displacement, use simple 513 // indirect register encoding, this handles addresses like [EAX]. The 514 // encoding for [EBP] with no displacement means [disp32] so we handle it 515 // by emitting a displacement of 0 below. 516 if (!DispForReloc && DispVal == 0 && BaseRegNo != N86::EBP) { 517 MCE.emitByte(ModRMByte(0, RegOpcodeField, BaseRegNo)); 518 return; 519 } 520 521 // Otherwise, if the displacement fits in a byte, encode as [REG+disp8]. 522 if (!DispForReloc && isDisp8(DispVal)) { 523 MCE.emitByte(ModRMByte(1, RegOpcodeField, BaseRegNo)); 524 emitConstant(DispVal, 1); 525 return; 526 } 527 528 // Otherwise, emit the most general non-SIB encoding: [REG+disp32] 529 MCE.emitByte(ModRMByte(2, RegOpcodeField, BaseRegNo)); 530 emitDisplacementField(DispForReloc, DispVal, PCAdj, IsPCRel); 531 return; 532 } 533 534 // Otherwise we need a SIB byte, so start by outputting the ModR/M byte first. 535 assert(IndexReg.getReg() != X86::ESP && 536 IndexReg.getReg() != X86::RSP && "Cannot use ESP as index reg!"); 537 538 bool ForceDisp32 = false; 539 bool ForceDisp8 = false; 540 if (BaseReg == 0) { 541 // If there is no base register, we emit the special case SIB byte with 542 // MOD=0, BASE=4, to JUST get the index, scale, and displacement. 543 MCE.emitByte(ModRMByte(0, RegOpcodeField, 4)); 544 ForceDisp32 = true; 545 } else if (DispForReloc) { 546 // Emit the normal disp32 encoding. 547 MCE.emitByte(ModRMByte(2, RegOpcodeField, 4)); 548 ForceDisp32 = true; 549 } else if (DispVal == 0 && BaseRegNo != N86::EBP) { 550 // Emit no displacement ModR/M byte 551 MCE.emitByte(ModRMByte(0, RegOpcodeField, 4)); 552 } else if (isDisp8(DispVal)) { 553 // Emit the disp8 encoding... 554 MCE.emitByte(ModRMByte(1, RegOpcodeField, 4)); 555 ForceDisp8 = true; // Make sure to force 8 bit disp if Base=EBP 556 } else { 557 // Emit the normal disp32 encoding... 558 MCE.emitByte(ModRMByte(2, RegOpcodeField, 4)); 559 } 560 561 // Calculate what the SS field value should be... 562 static const unsigned SSTable[] = { ~0U, 0, 1, ~0U, 2, ~0U, ~0U, ~0U, 3 }; 563 unsigned SS = SSTable[Scale.getImm()]; 564 565 if (BaseReg == 0) { 566 // Handle the SIB byte for the case where there is no base, see Intel 567 // Manual 2A, table 2-7. The displacement has already been output. 568 unsigned IndexRegNo; 569 if (IndexReg.getReg()) 570 IndexRegNo = X86_MC::getX86RegNum(IndexReg.getReg()); 571 else // Examples: [ESP+1*<noreg>+4] or [scaled idx]+disp32 (MOD=0,BASE=5) 572 IndexRegNo = 4; 573 emitSIBByte(SS, IndexRegNo, 5); 574 } else { 575 unsigned BaseRegNo = X86_MC::getX86RegNum(BaseReg); 576 unsigned IndexRegNo; 577 if (IndexReg.getReg()) 578 IndexRegNo = X86_MC::getX86RegNum(IndexReg.getReg()); 579 else 580 IndexRegNo = 4; // For example [ESP+1*<noreg>+4] 581 emitSIBByte(SS, IndexRegNo, BaseRegNo); 582 } 583 584 // Do we need to output a displacement? 585 if (ForceDisp8) { 586 emitConstant(DispVal, 1); 587 } else if (DispVal != 0 || ForceDisp32) { 588 emitDisplacementField(DispForReloc, DispVal, PCAdj, IsPCRel); 589 } 590 } 591 592 static const MCInstrDesc *UpdateOp(MachineInstr &MI, const X86InstrInfo *II, 593 unsigned Opcode) { 594 const MCInstrDesc *Desc = &II->get(Opcode); 595 MI.setDesc(*Desc); 596 return Desc; 597 } 598 599 template<class CodeEmitter> 600 void Emitter<CodeEmitter>::emitInstruction(MachineInstr &MI, 601 const MCInstrDesc *Desc) { 602 DEBUG(dbgs() << MI); 603 604 // If this is a pseudo instruction, lower it. 605 switch (Desc->getOpcode()) { 606 case X86::ADD16rr_DB: Desc = UpdateOp(MI, II, X86::OR16rr); break; 607 case X86::ADD32rr_DB: Desc = UpdateOp(MI, II, X86::OR32rr); break; 608 case X86::ADD64rr_DB: Desc = UpdateOp(MI, II, X86::OR64rr); break; 609 case X86::ADD16ri_DB: Desc = UpdateOp(MI, II, X86::OR16ri); break; 610 case X86::ADD32ri_DB: Desc = UpdateOp(MI, II, X86::OR32ri); break; 611 case X86::ADD64ri32_DB: Desc = UpdateOp(MI, II, X86::OR64ri32); break; 612 case X86::ADD16ri8_DB: Desc = UpdateOp(MI, II, X86::OR16ri8); break; 613 case X86::ADD32ri8_DB: Desc = UpdateOp(MI, II, X86::OR32ri8); break; 614 case X86::ADD64ri8_DB: Desc = UpdateOp(MI, II, X86::OR64ri8); break; 615 case X86::ACQUIRE_MOV8rm: Desc = UpdateOp(MI, II, X86::MOV8rm); break; 616 case X86::ACQUIRE_MOV16rm: Desc = UpdateOp(MI, II, X86::MOV16rm); break; 617 case X86::ACQUIRE_MOV32rm: Desc = UpdateOp(MI, II, X86::MOV32rm); break; 618 case X86::ACQUIRE_MOV64rm: Desc = UpdateOp(MI, II, X86::MOV64rm); break; 619 case X86::RELEASE_MOV8mr: Desc = UpdateOp(MI, II, X86::MOV8mr); break; 620 case X86::RELEASE_MOV16mr: Desc = UpdateOp(MI, II, X86::MOV16mr); break; 621 case X86::RELEASE_MOV32mr: Desc = UpdateOp(MI, II, X86::MOV32mr); break; 622 case X86::RELEASE_MOV64mr: Desc = UpdateOp(MI, II, X86::MOV64mr); break; 623 } 624 625 626 MCE.processDebugLoc(MI.getDebugLoc(), true); 627 628 unsigned Opcode = Desc->Opcode; 629 630 // Emit the lock opcode prefix as needed. 631 if (Desc->TSFlags & X86II::LOCK) 632 MCE.emitByte(0xF0); 633 634 // Emit segment override opcode prefix as needed. 635 switch (Desc->TSFlags & X86II::SegOvrMask) { 636 case X86II::FS: 637 MCE.emitByte(0x64); 638 break; 639 case X86II::GS: 640 MCE.emitByte(0x65); 641 break; 642 default: llvm_unreachable("Invalid segment!"); 643 case 0: break; // No segment override! 644 } 645 646 // Emit the repeat opcode prefix as needed. 647 if ((Desc->TSFlags & X86II::Op0Mask) == X86II::REP) 648 MCE.emitByte(0xF3); 649 650 // Emit the operand size opcode prefix as needed. 651 if (Desc->TSFlags & X86II::OpSize) 652 MCE.emitByte(0x66); 653 654 // Emit the address size opcode prefix as needed. 655 if (Desc->TSFlags & X86II::AdSize) 656 MCE.emitByte(0x67); 657 658 bool Need0FPrefix = false; 659 switch (Desc->TSFlags & X86II::Op0Mask) { 660 case X86II::TB: // Two-byte opcode prefix 661 case X86II::T8: // 0F 38 662 case X86II::TA: // 0F 3A 663 case X86II::A6: // 0F A6 664 case X86II::A7: // 0F A7 665 Need0FPrefix = true; 666 break; 667 case X86II::TF: // F2 0F 38 668 MCE.emitByte(0xF2); 669 Need0FPrefix = true; 670 break; 671 case X86II::REP: break; // already handled. 672 case X86II::XS: // F3 0F 673 MCE.emitByte(0xF3); 674 Need0FPrefix = true; 675 break; 676 case X86II::XD: // F2 0F 677 MCE.emitByte(0xF2); 678 Need0FPrefix = true; 679 break; 680 case X86II::D8: case X86II::D9: case X86II::DA: case X86II::DB: 681 case X86II::DC: case X86II::DD: case X86II::DE: case X86II::DF: 682 MCE.emitByte(0xD8+ 683 (((Desc->TSFlags & X86II::Op0Mask)-X86II::D8) 684 >> X86II::Op0Shift)); 685 break; // Two-byte opcode prefix 686 default: llvm_unreachable("Invalid prefix!"); 687 case 0: break; // No prefix! 688 } 689 690 // Handle REX prefix. 691 if (Is64BitMode) { 692 if (unsigned REX = determineREX(MI)) 693 MCE.emitByte(0x40 | REX); 694 } 695 696 // 0x0F escape code must be emitted just before the opcode. 697 if (Need0FPrefix) 698 MCE.emitByte(0x0F); 699 700 switch (Desc->TSFlags & X86II::Op0Mask) { 701 case X86II::TF: // F2 0F 38 702 case X86II::T8: // 0F 38 703 MCE.emitByte(0x38); 704 break; 705 case X86II::TA: // 0F 3A 706 MCE.emitByte(0x3A); 707 break; 708 case X86II::A6: // 0F A6 709 MCE.emitByte(0xA6); 710 break; 711 case X86II::A7: // 0F A7 712 MCE.emitByte(0xA7); 713 break; 714 } 715 716 // If this is a two-address instruction, skip one of the register operands. 717 unsigned NumOps = Desc->getNumOperands(); 718 unsigned CurOp = 0; 719 if (NumOps > 1 && Desc->getOperandConstraint(1, MCOI::TIED_TO) != -1) 720 ++CurOp; 721 else if (NumOps > 2 && Desc->getOperandConstraint(NumOps-1,MCOI::TIED_TO)== 0) 722 // Skip the last source operand that is tied_to the dest reg. e.g. LXADD32 723 --NumOps; 724 725 unsigned char BaseOpcode = X86II::getBaseOpcodeFor(Desc->TSFlags); 726 switch (Desc->TSFlags & X86II::FormMask) { 727 default: 728 llvm_unreachable("Unknown FormMask value in X86 MachineCodeEmitter!"); 729 case X86II::Pseudo: 730 // Remember the current PC offset, this is the PIC relocation 731 // base address. 732 switch (Opcode) { 733 default: 734 llvm_unreachable("pseudo instructions should be removed before code" 735 " emission"); 736 break; 737 // Do nothing for Int_MemBarrier - it's just a comment. Add a debug 738 // to make it slightly easier to see. 739 case X86::Int_MemBarrier: 740 DEBUG(dbgs() << "#MEMBARRIER\n"); 741 break; 742 743 case TargetOpcode::INLINEASM: 744 // We allow inline assembler nodes with empty bodies - they can 745 // implicitly define registers, which is ok for JIT. 746 if (MI.getOperand(0).getSymbolName()[0]) 747 report_fatal_error("JIT does not support inline asm!"); 748 break; 749 case TargetOpcode::PROLOG_LABEL: 750 case TargetOpcode::GC_LABEL: 751 case TargetOpcode::EH_LABEL: 752 MCE.emitLabel(MI.getOperand(0).getMCSymbol()); 753 break; 754 755 case TargetOpcode::IMPLICIT_DEF: 756 case TargetOpcode::KILL: 757 break; 758 case X86::MOVPC32r: { 759 // This emits the "call" portion of this pseudo instruction. 760 MCE.emitByte(BaseOpcode); 761 emitConstant(0, X86II::getSizeOfImm(Desc->TSFlags)); 762 // Remember PIC base. 763 PICBaseOffset = (intptr_t) MCE.getCurrentPCOffset(); 764 X86JITInfo *JTI = TM.getJITInfo(); 765 JTI->setPICBase(MCE.getCurrentPCValue()); 766 break; 767 } 768 } 769 CurOp = NumOps; 770 break; 771 case X86II::RawFrm: { 772 MCE.emitByte(BaseOpcode); 773 774 if (CurOp == NumOps) 775 break; 776 777 const MachineOperand &MO = MI.getOperand(CurOp++); 778 779 DEBUG(dbgs() << "RawFrm CurOp " << CurOp << "\n"); 780 DEBUG(dbgs() << "isMBB " << MO.isMBB() << "\n"); 781 DEBUG(dbgs() << "isGlobal " << MO.isGlobal() << "\n"); 782 DEBUG(dbgs() << "isSymbol " << MO.isSymbol() << "\n"); 783 DEBUG(dbgs() << "isImm " << MO.isImm() << "\n"); 784 785 if (MO.isMBB()) { 786 emitPCRelativeBlockAddress(MO.getMBB()); 787 break; 788 } 789 790 if (MO.isGlobal()) { 791 emitGlobalAddress(MO.getGlobal(), X86::reloc_pcrel_word, 792 MO.getOffset(), 0); 793 break; 794 } 795 796 if (MO.isSymbol()) { 797 emitExternalSymbolAddress(MO.getSymbolName(), X86::reloc_pcrel_word); 798 break; 799 } 800 801 // FIXME: Only used by hackish MCCodeEmitter, remove when dead. 802 if (MO.isJTI()) { 803 emitJumpTableAddress(MO.getIndex(), X86::reloc_pcrel_word); 804 break; 805 } 806 807 assert(MO.isImm() && "Unknown RawFrm operand!"); 808 if (Opcode == X86::CALLpcrel32 || Opcode == X86::CALL64pcrel32 || 809 Opcode == X86::WINCALL64pcrel32) { 810 // Fix up immediate operand for pc relative calls. 811 intptr_t Imm = (intptr_t)MO.getImm(); 812 Imm = Imm - MCE.getCurrentPCValue() - 4; 813 emitConstant(Imm, X86II::getSizeOfImm(Desc->TSFlags)); 814 } else 815 emitConstant(MO.getImm(), X86II::getSizeOfImm(Desc->TSFlags)); 816 break; 817 } 818 819 case X86II::AddRegFrm: { 820 MCE.emitByte(BaseOpcode + 821 X86_MC::getX86RegNum(MI.getOperand(CurOp++).getReg())); 822 823 if (CurOp == NumOps) 824 break; 825 826 const MachineOperand &MO1 = MI.getOperand(CurOp++); 827 unsigned Size = X86II::getSizeOfImm(Desc->TSFlags); 828 if (MO1.isImm()) { 829 emitConstant(MO1.getImm(), Size); 830 break; 831 } 832 833 unsigned rt = Is64BitMode ? X86::reloc_pcrel_word 834 : (IsPIC ? X86::reloc_picrel_word : X86::reloc_absolute_word); 835 if (Opcode == X86::MOV64ri64i32) 836 rt = X86::reloc_absolute_word; // FIXME: add X86II flag? 837 // This should not occur on Darwin for relocatable objects. 838 if (Opcode == X86::MOV64ri) 839 rt = X86::reloc_absolute_dword; // FIXME: add X86II flag? 840 if (MO1.isGlobal()) { 841 bool Indirect = gvNeedsNonLazyPtr(MO1, TM); 842 emitGlobalAddress(MO1.getGlobal(), rt, MO1.getOffset(), 0, 843 Indirect); 844 } else if (MO1.isSymbol()) 845 emitExternalSymbolAddress(MO1.getSymbolName(), rt); 846 else if (MO1.isCPI()) 847 emitConstPoolAddress(MO1.getIndex(), rt); 848 else if (MO1.isJTI()) 849 emitJumpTableAddress(MO1.getIndex(), rt); 850 break; 851 } 852 853 case X86II::MRMDestReg: { 854 MCE.emitByte(BaseOpcode); 855 emitRegModRMByte(MI.getOperand(CurOp).getReg(), 856 X86_MC::getX86RegNum(MI.getOperand(CurOp+1).getReg())); 857 CurOp += 2; 858 if (CurOp != NumOps) 859 emitConstant(MI.getOperand(CurOp++).getImm(), 860 X86II::getSizeOfImm(Desc->TSFlags)); 861 break; 862 } 863 case X86II::MRMDestMem: { 864 MCE.emitByte(BaseOpcode); 865 emitMemModRMByte(MI, CurOp, 866 X86_MC::getX86RegNum(MI.getOperand(CurOp + X86::AddrNumOperands) 867 .getReg())); 868 CurOp += X86::AddrNumOperands + 1; 869 if (CurOp != NumOps) 870 emitConstant(MI.getOperand(CurOp++).getImm(), 871 X86II::getSizeOfImm(Desc->TSFlags)); 872 break; 873 } 874 875 case X86II::MRMSrcReg: 876 MCE.emitByte(BaseOpcode); 877 emitRegModRMByte(MI.getOperand(CurOp+1).getReg(), 878 X86_MC::getX86RegNum(MI.getOperand(CurOp).getReg())); 879 CurOp += 2; 880 if (CurOp != NumOps) 881 emitConstant(MI.getOperand(CurOp++).getImm(), 882 X86II::getSizeOfImm(Desc->TSFlags)); 883 break; 884 885 case X86II::MRMSrcMem: { 886 int AddrOperands = X86::AddrNumOperands; 887 888 intptr_t PCAdj = (CurOp + AddrOperands + 1 != NumOps) ? 889 X86II::getSizeOfImm(Desc->TSFlags) : 0; 890 891 MCE.emitByte(BaseOpcode); 892 emitMemModRMByte(MI, CurOp+1, 893 X86_MC::getX86RegNum(MI.getOperand(CurOp).getReg()),PCAdj); 894 CurOp += AddrOperands + 1; 895 if (CurOp != NumOps) 896 emitConstant(MI.getOperand(CurOp++).getImm(), 897 X86II::getSizeOfImm(Desc->TSFlags)); 898 break; 899 } 900 901 case X86II::MRM0r: case X86II::MRM1r: 902 case X86II::MRM2r: case X86II::MRM3r: 903 case X86II::MRM4r: case X86II::MRM5r: 904 case X86II::MRM6r: case X86II::MRM7r: { 905 MCE.emitByte(BaseOpcode); 906 emitRegModRMByte(MI.getOperand(CurOp++).getReg(), 907 (Desc->TSFlags & X86II::FormMask)-X86II::MRM0r); 908 909 if (CurOp == NumOps) 910 break; 911 912 const MachineOperand &MO1 = MI.getOperand(CurOp++); 913 unsigned Size = X86II::getSizeOfImm(Desc->TSFlags); 914 if (MO1.isImm()) { 915 emitConstant(MO1.getImm(), Size); 916 break; 917 } 918 919 unsigned rt = Is64BitMode ? X86::reloc_pcrel_word 920 : (IsPIC ? X86::reloc_picrel_word : X86::reloc_absolute_word); 921 if (Opcode == X86::MOV64ri32) 922 rt = X86::reloc_absolute_word_sext; // FIXME: add X86II flag? 923 if (MO1.isGlobal()) { 924 bool Indirect = gvNeedsNonLazyPtr(MO1, TM); 925 emitGlobalAddress(MO1.getGlobal(), rt, MO1.getOffset(), 0, 926 Indirect); 927 } else if (MO1.isSymbol()) 928 emitExternalSymbolAddress(MO1.getSymbolName(), rt); 929 else if (MO1.isCPI()) 930 emitConstPoolAddress(MO1.getIndex(), rt); 931 else if (MO1.isJTI()) 932 emitJumpTableAddress(MO1.getIndex(), rt); 933 break; 934 } 935 936 case X86II::MRM0m: case X86II::MRM1m: 937 case X86II::MRM2m: case X86II::MRM3m: 938 case X86II::MRM4m: case X86II::MRM5m: 939 case X86II::MRM6m: case X86II::MRM7m: { 940 intptr_t PCAdj = (CurOp + X86::AddrNumOperands != NumOps) ? 941 (MI.getOperand(CurOp+X86::AddrNumOperands).isImm() ? 942 X86II::getSizeOfImm(Desc->TSFlags) : 4) : 0; 943 944 MCE.emitByte(BaseOpcode); 945 emitMemModRMByte(MI, CurOp, (Desc->TSFlags & X86II::FormMask)-X86II::MRM0m, 946 PCAdj); 947 CurOp += X86::AddrNumOperands; 948 949 if (CurOp == NumOps) 950 break; 951 952 const MachineOperand &MO = MI.getOperand(CurOp++); 953 unsigned Size = X86II::getSizeOfImm(Desc->TSFlags); 954 if (MO.isImm()) { 955 emitConstant(MO.getImm(), Size); 956 break; 957 } 958 959 unsigned rt = Is64BitMode ? X86::reloc_pcrel_word 960 : (IsPIC ? X86::reloc_picrel_word : X86::reloc_absolute_word); 961 if (Opcode == X86::MOV64mi32) 962 rt = X86::reloc_absolute_word_sext; // FIXME: add X86II flag? 963 if (MO.isGlobal()) { 964 bool Indirect = gvNeedsNonLazyPtr(MO, TM); 965 emitGlobalAddress(MO.getGlobal(), rt, MO.getOffset(), 0, 966 Indirect); 967 } else if (MO.isSymbol()) 968 emitExternalSymbolAddress(MO.getSymbolName(), rt); 969 else if (MO.isCPI()) 970 emitConstPoolAddress(MO.getIndex(), rt); 971 else if (MO.isJTI()) 972 emitJumpTableAddress(MO.getIndex(), rt); 973 break; 974 } 975 976 case X86II::MRMInitReg: 977 MCE.emitByte(BaseOpcode); 978 // Duplicate register, used by things like MOV8r0 (aka xor reg,reg). 979 emitRegModRMByte(MI.getOperand(CurOp).getReg(), 980 X86_MC::getX86RegNum(MI.getOperand(CurOp).getReg())); 981 ++CurOp; 982 break; 983 984 case X86II::MRM_C1: 985 MCE.emitByte(BaseOpcode); 986 MCE.emitByte(0xC1); 987 break; 988 case X86II::MRM_C8: 989 MCE.emitByte(BaseOpcode); 990 MCE.emitByte(0xC8); 991 break; 992 case X86II::MRM_C9: 993 MCE.emitByte(BaseOpcode); 994 MCE.emitByte(0xC9); 995 break; 996 case X86II::MRM_E8: 997 MCE.emitByte(BaseOpcode); 998 MCE.emitByte(0xE8); 999 break; 1000 case X86II::MRM_F0: 1001 MCE.emitByte(BaseOpcode); 1002 MCE.emitByte(0xF0); 1003 break; 1004 } 1005 1006 if (!Desc->isVariadic() && CurOp != NumOps) { 1007 #ifndef NDEBUG 1008 dbgs() << "Cannot encode all operands of: " << MI << "\n"; 1009 #endif 1010 llvm_unreachable(0); 1011 } 1012 1013 MCE.processDebugLoc(MI.getDebugLoc(), false); 1014 } 1015
