lib/Target/X86/X86AsmPrinter.cpp

   1 //===-- X86AsmPrinter.cpp - Convert X86 LLVM code to AT&T assembly --------===//
   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 // This file contains a printer that converts from our internal representation
  10 // of machine-dependent LLVM code to X86 machine code.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "X86AsmPrinter.h"
  15 #include "MCTargetDesc/X86ATTInstPrinter.h"
  16 #include "MCTargetDesc/X86BaseInfo.h"
  17 #include "MCTargetDesc/X86TargetStreamer.h"
  18 #include "TargetInfo/X86TargetInfo.h"
  19 #include "X86InstrInfo.h"
  20 #include "X86MachineFunctionInfo.h"
  21 #include "llvm/BinaryFormat/COFF.h"
  22 #include "llvm/BinaryFormat/ELF.h"
  23 #include "llvm/CodeGen/MachineConstantPool.h"
  24 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
  25 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
  26 #include "llvm/IR/DerivedTypes.h"
  27 #include "llvm/IR/InlineAsm.h"
  28 #include "llvm/IR/Mangler.h"
  29 #include "llvm/IR/Module.h"
  30 #include "llvm/IR/Type.h"
  31 #include "llvm/MC/MCCodeEmitter.h"
  32 #include "llvm/MC/MCContext.h"
  33 #include "llvm/MC/MCExpr.h"
  34 #include "llvm/MC/MCSectionCOFF.h"
  35 #include "llvm/MC/MCSectionELF.h"
  36 #include "llvm/MC/MCSectionMachO.h"
  37 #include "llvm/MC/MCStreamer.h"
  38 #include "llvm/MC/MCSymbol.h"
  39 #include "llvm/Support/Debug.h"
  40 #include "llvm/Support/ErrorHandling.h"
  41 #include "llvm/Support/MachineValueType.h"
  42 #include "llvm/Support/TargetRegistry.h"
  43 using namespace llvm;
  44
  45 X86AsmPrinter::X86AsmPrinter(TargetMachine &TM,
  46                              std::unique_ptr<MCStreamer> Streamer)
  47     : AsmPrinter(TM, std::move(Streamer)), SM(*this), FM(*this) {}
  48
  49 //===----------------------------------------------------------------------===//
  50 // Primitive Helper Functions.
  51 //===----------------------------------------------------------------------===//
  52
  53 /// runOnMachineFunction - Emit the function body.
  54 ///
  55 bool X86AsmPrinter::runOnMachineFunction(MachineFunction &MF) {
  56   Subtarget = &MF.getSubtarget<X86Subtarget>();
  57
  58   SMShadowTracker.startFunction(MF);
  59   CodeEmitter.reset(TM.getTarget().createMCCodeEmitter(
  60       *Subtarget->getInstrInfo(), *Subtarget->getRegisterInfo(),
  61       MF.getContext()));
  62
  63   EmitFPOData =
  64       Subtarget->isTargetWin32() && MF.getMMI().getModule()->getCodeViewFlag();
  65
  66   SetupMachineFunction(MF);
  67
  68   if (Subtarget->isTargetCOFF()) {
  69     bool Local = MF.getFunction().hasLocalLinkage();
  70     OutStreamer->BeginCOFFSymbolDef(CurrentFnSym);
  71     OutStreamer->EmitCOFFSymbolStorageClass(
  72         Local ? COFF::IMAGE_SYM_CLASS_STATIC : COFF::IMAGE_SYM_CLASS_EXTERNAL);
  73     OutStreamer->EmitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_FUNCTION
  74                                                << COFF::SCT_COMPLEX_TYPE_SHIFT);
  75     OutStreamer->EndCOFFSymbolDef();
  76   }
  77
  78   // Emit the rest of the function body.
  79   EmitFunctionBody();
  80
  81   // Emit the XRay table for this function.
  82   emitXRayTable();
  83
  84   EmitFPOData = false;
  85
  86   // We didn't modify anything.
  87   return false;
  88 }
  89
  90 void X86AsmPrinter::EmitFunctionBodyStart() {
  91   if (EmitFPOData) {
  92     if (auto *XTS =
  93         static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer()))
  94       XTS->emitFPOProc(
  95           CurrentFnSym,
  96           MF->getInfo<X86MachineFunctionInfo>()->getArgumentStackSize());
  97   }
  98 }
  99
 100 void X86AsmPrinter::EmitFunctionBodyEnd() {
 101   if (EmitFPOData) {
 102     if (auto *XTS =
 103             static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer()))
 104       XTS->emitFPOEndProc();
 105   }
 106 }
 107
 108 /// PrintSymbolOperand - Print a raw symbol reference operand.  This handles
 109 /// jump tables, constant pools, global address and external symbols, all of
 110 /// which print to a label with various suffixes for relocation types etc.
 111 void X86AsmPrinter::PrintSymbolOperand(const MachineOperand &MO,
 112                                        raw_ostream &O) {
 113   switch (MO.getType()) {
 114   default: llvm_unreachable("unknown symbol type!");
 115   case MachineOperand::MO_ConstantPoolIndex:
 116     GetCPISymbol(MO.getIndex())->print(O, MAI);
 117     printOffset(MO.getOffset(), O);
 118     break;
 119   case MachineOperand::MO_GlobalAddress: {
 120     const GlobalValue *GV = MO.getGlobal();
 121
 122     MCSymbol *GVSym;
 123     if (MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY ||
 124         MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY_PIC_BASE)
 125       GVSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
 126     else
 127       GVSym = getSymbol(GV);
 128
 129     // Handle dllimport linkage.
 130     if (MO.getTargetFlags() == X86II::MO_DLLIMPORT)
 131       GVSym = OutContext.getOrCreateSymbol(Twine("__imp_") + GVSym->getName());
 132     else if (MO.getTargetFlags() == X86II::MO_COFFSTUB)
 133       GVSym =
 134           OutContext.getOrCreateSymbol(Twine(".refptr.") + GVSym->getName());
 135
 136     if (MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY ||
 137         MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY_PIC_BASE) {
 138       MCSymbol *Sym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
 139       MachineModuleInfoImpl::StubValueTy &StubSym =
 140           MMI->getObjFileInfo<MachineModuleInfoMachO>().getGVStubEntry(Sym);
 141       if (!StubSym.getPointer())
 142         StubSym = MachineModuleInfoImpl::StubValueTy(getSymbol(GV),
 143                                                      !GV->hasInternalLinkage());
 144     }
 145
 146     // If the name begins with a dollar-sign, enclose it in parens.  We do this
 147     // to avoid having it look like an integer immediate to the assembler.
 148     if (GVSym->getName()[0] != '$')
 149       GVSym->print(O, MAI);
 150     else {
 151       O << '(';
 152       GVSym->print(O, MAI);
 153       O << ')';
 154     }
 155     printOffset(MO.getOffset(), O);
 156     break;
 157   }
 158   }
 159
 160   switch (MO.getTargetFlags()) {
 161   default:
 162     llvm_unreachable("Unknown target flag on GV operand");
 163   case X86II::MO_NO_FLAG:    // No flag.
 164     break;
 165   case X86II::MO_DARWIN_NONLAZY:
 166   case X86II::MO_DLLIMPORT:
 167   case X86II::MO_COFFSTUB:
 168     // These affect the name of the symbol, not any suffix.
 169     break;
 170   case X86II::MO_GOT_ABSOLUTE_ADDRESS:
 171     O << " + [.-";
 172     MF->getPICBaseSymbol()->print(O, MAI);
 173     O << ']';
 174     break;
 175   case X86II::MO_PIC_BASE_OFFSET:
 176   case X86II::MO_DARWIN_NONLAZY_PIC_BASE:
 177     O << '-';
 178     MF->getPICBaseSymbol()->print(O, MAI);
 179     break;
 180   case X86II::MO_TLSGD:     O << "@TLSGD";     break;
 181   case X86II::MO_TLSLD:     O << "@TLSLD";     break;
 182   case X86II::MO_TLSLDM:    O << "@TLSLDM";    break;
 183   case X86II::MO_GOTTPOFF:  O << "@GOTTPOFF";  break;
 184   case X86II::MO_INDNTPOFF: O << "@INDNTPOFF"; break;
 185   case X86II::MO_TPOFF:     O << "@TPOFF";     break;
 186   case X86II::MO_DTPOFF:    O << "@DTPOFF";    break;
 187   case X86II::MO_NTPOFF:    O << "@NTPOFF";    break;
 188   case X86II::MO_GOTNTPOFF: O << "@GOTNTPOFF"; break;
 189   case X86II::MO_GOTPCREL:  O << "@GOTPCREL";  break;
 190   case X86II::MO_GOT:       O << "@GOT";       break;
 191   case X86II::MO_GOTOFF:    O << "@GOTOFF";    break;
 192   case X86II::MO_PLT:       O << "@PLT";       break;
 193   case X86II::MO_TLVP:      O << "@TLVP";      break;
 194   case X86II::MO_TLVP_PIC_BASE:
 195     O << "@TLVP" << '-';
 196     MF->getPICBaseSymbol()->print(O, MAI);
 197     break;
 198   case X86II::MO_SECREL:    O << "@SECREL32";  break;
 199   }
 200 }
 201
 202 void X86AsmPrinter::PrintOperand(const MachineInstr *MI, unsigned OpNo,
 203                                  raw_ostream &O) {
 204   const MachineOperand &MO = MI->getOperand(OpNo);
 205   const bool IsATT = MI->getInlineAsmDialect() == InlineAsm::AD_ATT;
 206   switch (MO.getType()) {
 207   default: llvm_unreachable("unknown operand type!");
 208   case MachineOperand::MO_Register: {
 209     if (IsATT)
 210       O << '%';
 211     O << X86ATTInstPrinter::getRegisterName(MO.getReg());
 212     return;
 213   }
 214
 215   case MachineOperand::MO_Immediate:
 216     if (IsATT)
 217       O << '$';
 218     O << MO.getImm();
 219     return;
 220
 221   case MachineOperand::MO_GlobalAddress: {
 222     if (IsATT)
 223       O << '$';
 224     PrintSymbolOperand(MO, O);
 225     break;
 226   }
 227   case MachineOperand::MO_BlockAddress: {
 228     MCSymbol *Sym = GetBlockAddressSymbol(MO.getBlockAddress());
 229     Sym->print(O, MAI);
 230     break;
 231   }
 232   }
 233 }
 234
 235 /// PrintModifiedOperand - Print subregisters based on supplied modifier,
 236 /// deferring to PrintOperand() if no modifier was supplied or if operand is not
 237 /// a register.
 238 void X86AsmPrinter::PrintModifiedOperand(const MachineInstr *MI, unsigned OpNo,
 239                                          raw_ostream &O, const char *Modifier) {
 240   const MachineOperand &MO = MI->getOperand(OpNo);
 241   if (!Modifier || MO.getType() != MachineOperand::MO_Register)
 242     return PrintOperand(MI, OpNo, O);
 243   if (MI->getInlineAsmDialect() == InlineAsm::AD_ATT)
 244     O << '%';
 245   Register Reg = MO.getReg();
 246   if (strncmp(Modifier, "subreg", strlen("subreg")) == 0) {
 247     unsigned Size = (strcmp(Modifier+6,"64") == 0) ? 64 :
 248         (strcmp(Modifier+6,"32") == 0) ? 32 :
 249         (strcmp(Modifier+6,"16") == 0) ? 16 : 8;
 250     Reg = getX86SubSuperRegister(Reg, Size);
 251   }
 252   O << X86ATTInstPrinter::getRegisterName(Reg);
 253 }
 254
 255 /// PrintPCRelImm - This is used to print an immediate value that ends up
 256 /// being encoded as a pc-relative value.  These print slightly differently, for
 257 /// example, a $ is not emitted.
 258 void X86AsmPrinter::PrintPCRelImm(const MachineInstr *MI, unsigned OpNo,
 259                                   raw_ostream &O) {
 260   const MachineOperand &MO = MI->getOperand(OpNo);
 261   switch (MO.getType()) {
 262   default: llvm_unreachable("Unknown pcrel immediate operand");
 263   case MachineOperand::MO_Register:
 264     // pc-relativeness was handled when computing the value in the reg.
 265     PrintOperand(MI, OpNo, O);
 266     return;
 267   case MachineOperand::MO_Immediate:
 268     O << MO.getImm();
 269     return;
 270   case MachineOperand::MO_GlobalAddress:
 271     PrintSymbolOperand(MO, O);
 272     return;
 273   }
 274 }
 275
 276 void X86AsmPrinter::PrintLeaMemReference(const MachineInstr *MI, unsigned OpNo,
 277                                          raw_ostream &O, const char *Modifier) {
 278   const MachineOperand &BaseReg = MI->getOperand(OpNo + X86::AddrBaseReg);
 279   const MachineOperand &IndexReg = MI->getOperand(OpNo + X86::AddrIndexReg);
 280   const MachineOperand &DispSpec = MI->getOperand(OpNo + X86::AddrDisp);
 281
 282   // If we really don't want to print out (rip), don't.
 283   bool HasBaseReg = BaseReg.getReg() != 0;
 284   if (HasBaseReg && Modifier && !strcmp(Modifier, "no-rip") &&
 285       BaseReg.getReg() == X86::RIP)
 286     HasBaseReg = false;
 287
 288   // HasParenPart - True if we will print out the () part of the mem ref.
 289   bool HasParenPart = IndexReg.getReg() || HasBaseReg;
 290
 291   switch (DispSpec.getType()) {
 292   default:
 293     llvm_unreachable("unknown operand type!");
 294   case MachineOperand::MO_Immediate: {
 295     int DispVal = DispSpec.getImm();
 296     if (DispVal || !HasParenPart)
 297       O << DispVal;
 298     break;
 299   }
 300   case MachineOperand::MO_GlobalAddress:
 301   case MachineOperand::MO_ConstantPoolIndex:
 302     PrintSymbolOperand(DispSpec, O);
 303     break;
 304   }
 305
 306   if (Modifier && strcmp(Modifier, "H") == 0)
 307     O << "+8";
 308
 309   if (HasParenPart) {
 310     assert(IndexReg.getReg() != X86::ESP &&
 311            "X86 doesn't allow scaling by ESP");
 312
 313     O << '(';
 314     if (HasBaseReg)
 315       PrintModifiedOperand(MI, OpNo + X86::AddrBaseReg, O, Modifier);
 316
 317     if (IndexReg.getReg()) {
 318       O << ',';
 319       PrintModifiedOperand(MI, OpNo + X86::AddrIndexReg, O, Modifier);
 320       unsigned ScaleVal = MI->getOperand(OpNo + X86::AddrScaleAmt).getImm();
 321       if (ScaleVal != 1)
 322         O << ',' << ScaleVal;
 323     }
 324     O << ')';
 325   }
 326 }
 327
 328 void X86AsmPrinter::PrintMemReference(const MachineInstr *MI, unsigned OpNo,
 329                                       raw_ostream &O, const char *Modifier) {
 330   assert(isMem(*MI, OpNo) && "Invalid memory reference!");
 331   const MachineOperand &Segment = MI->getOperand(OpNo + X86::AddrSegmentReg);
 332   if (Segment.getReg()) {
 333     PrintModifiedOperand(MI, OpNo + X86::AddrSegmentReg, O, Modifier);
 334     O << ':';
 335   }
 336   PrintLeaMemReference(MI, OpNo, O, Modifier);
 337 }
 338
 339 void X86AsmPrinter::PrintIntelMemReference(const MachineInstr *MI,
 340                                            unsigned OpNo, raw_ostream &O) {
 341   const MachineOperand &BaseReg = MI->getOperand(OpNo + X86::AddrBaseReg);
 342   unsigned ScaleVal = MI->getOperand(OpNo + X86::AddrScaleAmt).getImm();
 343   const MachineOperand &IndexReg = MI->getOperand(OpNo + X86::AddrIndexReg);
 344   const MachineOperand &DispSpec = MI->getOperand(OpNo + X86::AddrDisp);
 345   const MachineOperand &SegReg = MI->getOperand(OpNo + X86::AddrSegmentReg);
 346
 347   // If this has a segment register, print it.
 348   if (SegReg.getReg()) {
 349     PrintOperand(MI, OpNo + X86::AddrSegmentReg, O);
 350     O << ':';
 351   }
 352
 353   O << '[';
 354
 355   bool NeedPlus = false;
 356   if (BaseReg.getReg()) {
 357     PrintOperand(MI, OpNo + X86::AddrBaseReg, O);
 358     NeedPlus = true;
 359   }
 360
 361   if (IndexReg.getReg()) {
 362     if (NeedPlus) O << " + ";
 363     if (ScaleVal != 1)
 364       O << ScaleVal << '*';
 365     PrintOperand(MI, OpNo + X86::AddrIndexReg, O);
 366     NeedPlus = true;
 367   }
 368
 369   if (!DispSpec.isImm()) {
 370     if (NeedPlus) O << " + ";
 371     PrintOperand(MI, OpNo + X86::AddrDisp, O);
 372   } else {
 373     int64_t DispVal = DispSpec.getImm();
 374     if (DispVal || (!IndexReg.getReg() && !BaseReg.getReg())) {
 375       if (NeedPlus) {
 376         if (DispVal > 0)
 377           O << " + ";
 378         else {
 379           O << " - ";
 380           DispVal = -DispVal;
 381         }
 382       }
 383       O << DispVal;
 384     }
 385   }
 386   O << ']';
 387 }
 388
 389 static bool printAsmMRegister(X86AsmPrinter &P, const MachineOperand &MO,
 390                               char Mode, raw_ostream &O) {
 391   Register Reg = MO.getReg();
 392   bool EmitPercent = true;
 393
 394   if (!X86::GR8RegClass.contains(Reg) &&
 395       !X86::GR16RegClass.contains(Reg) &&
 396       !X86::GR32RegClass.contains(Reg) &&
 397       !X86::GR64RegClass.contains(Reg))
 398     return true;
 399
 400   switch (Mode) {
 401   default: return true;  // Unknown mode.
 402   case 'b': // Print QImode register
 403     Reg = getX86SubSuperRegister(Reg, 8);
 404     break;
 405   case 'h': // Print QImode high register
 406     Reg = getX86SubSuperRegister(Reg, 8, true);
 407     break;
 408   case 'w': // Print HImode register
 409     Reg = getX86SubSuperRegister(Reg, 16);
 410     break;
 411   case 'k': // Print SImode register
 412     Reg = getX86SubSuperRegister(Reg, 32);
 413     break;
 414   case 'V':
 415     EmitPercent = false;
 416     LLVM_FALLTHROUGH;
 417   case 'q':
 418     // Print 64-bit register names if 64-bit integer registers are available.
 419     // Otherwise, print 32-bit register names.
 420     Reg = getX86SubSuperRegister(Reg, P.getSubtarget().is64Bit() ? 64 : 32);
 421     break;
 422   }
 423
 424   if (EmitPercent)
 425     O << '%';
 426
 427   O << X86ATTInstPrinter::getRegisterName(Reg);
 428   return false;
 429 }
 430
 431 /// PrintAsmOperand - Print out an operand for an inline asm expression.
 432 ///
 433 bool X86AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
 434                                     const char *ExtraCode, raw_ostream &O) {
 435   // Does this asm operand have a single letter operand modifier?
 436   if (ExtraCode && ExtraCode[0]) {
 437     if (ExtraCode[1] != 0) return true; // Unknown modifier.
 438
 439     const MachineOperand &MO = MI->getOperand(OpNo);
 440
 441     switch (ExtraCode[0]) {
 442     default:
 443       // See if this is a generic print operand
 444       return AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, O);
 445     case 'a': // This is an address.  Currently only 'i' and 'r' are expected.
 446       switch (MO.getType()) {
 447       default:
 448         return true;
 449       case MachineOperand::MO_Immediate:
 450         O << MO.getImm();
 451         return false;
 452       case MachineOperand::MO_ConstantPoolIndex:
 453       case MachineOperand::MO_JumpTableIndex:
 454       case MachineOperand::MO_ExternalSymbol:
 455         llvm_unreachable("unexpected operand type!");
 456       case MachineOperand::MO_GlobalAddress:
 457         PrintSymbolOperand(MO, O);
 458         if (Subtarget->isPICStyleRIPRel())
 459           O << "(%rip)";
 460         return false;
 461       case MachineOperand::MO_Register:
 462         O << '(';
 463         PrintOperand(MI, OpNo, O);
 464         O << ')';
 465         return false;
 466       }
 467
 468     case 'c': // Don't print "$" before a global var name or constant.
 469       switch (MO.getType()) {
 470       default:
 471         PrintOperand(MI, OpNo, O);
 472         break;
 473       case MachineOperand::MO_Immediate:
 474         O << MO.getImm();
 475         break;
 476       case MachineOperand::MO_ConstantPoolIndex:
 477       case MachineOperand::MO_JumpTableIndex:
 478       case MachineOperand::MO_ExternalSymbol:
 479         llvm_unreachable("unexpected operand type!");
 480       case MachineOperand::MO_GlobalAddress:
 481         PrintSymbolOperand(MO, O);
 482         break;
 483       }
 484       return false;
 485
 486     case 'A': // Print '*' before a register (it must be a register)
 487       if (MO.isReg()) {
 488         O << '*';
 489         PrintOperand(MI, OpNo, O);
 490         return false;
 491       }
 492       return true;
 493
 494     case 'b': // Print QImode register
 495     case 'h': // Print QImode high register
 496     case 'w': // Print HImode register
 497     case 'k': // Print SImode register
 498     case 'q': // Print DImode register
 499     case 'V': // Print native register without '%'
 500       if (MO.isReg())
 501         return printAsmMRegister(*this, MO, ExtraCode[0], O);
 502       PrintOperand(MI, OpNo, O);
 503       return false;
 504
 505     case 'P': // This is the operand of a call, treat specially.
 506       PrintPCRelImm(MI, OpNo, O);
 507       return false;
 508
 509     case 'n': // Negate the immediate or print a '-' before the operand.
 510       // Note: this is a temporary solution. It should be handled target
 511       // independently as part of the 'MC' work.
 512       if (MO.isImm()) {
 513         O << -MO.getImm();
 514         return false;
 515       }
 516       O << '-';
 517     }
 518   }
 519
 520   PrintOperand(MI, OpNo, O);
 521   return false;
 522 }
 523
 524 bool X86AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
 525                                           const char *ExtraCode,
 526                                           raw_ostream &O) {
 527   if (MI->getInlineAsmDialect() == InlineAsm::AD_Intel) {
 528     PrintIntelMemReference(MI, OpNo, O);
 529     return false;
 530   }
 531
 532   if (ExtraCode && ExtraCode[0]) {
 533     if (ExtraCode[1] != 0) return true; // Unknown modifier.
 534
 535     switch (ExtraCode[0]) {
 536     default: return true;  // Unknown modifier.
 537     case 'b': // Print QImode register
 538     case 'h': // Print QImode high register
 539     case 'w': // Print HImode register
 540     case 'k': // Print SImode register
 541     case 'q': // Print SImode register
 542       // These only apply to registers, ignore on mem.
 543       break;
 544     case 'H':
 545       PrintMemReference(MI, OpNo, O, "H");
 546       return false;
 547     case 'P': // Don't print @PLT, but do print as memory.
 548       PrintMemReference(MI, OpNo, O, "no-rip");
 549       return false;
 550     }
 551   }
 552   PrintMemReference(MI, OpNo, O, nullptr);
 553   return false;
 554 }
 555
 556 void X86AsmPrinter::EmitStartOfAsmFile(Module &M) {
 557   const Triple &TT = TM.getTargetTriple();
 558
 559   if (TT.isOSBinFormatELF()) {
 560     // Assemble feature flags that may require creation of a note section.
 561     unsigned FeatureFlagsAnd = 0;
 562     if (M.getModuleFlag("cf-protection-branch"))
 563       FeatureFlagsAnd |= ELF::GNU_PROPERTY_X86_FEATURE_1_IBT;
 564     if (M.getModuleFlag("cf-protection-return"))
 565       FeatureFlagsAnd |= ELF::GNU_PROPERTY_X86_FEATURE_1_SHSTK;
 566
 567     if (FeatureFlagsAnd) {
 568       // Emit a .note.gnu.property section with the flags.
 569       if (!TT.isArch32Bit() && !TT.isArch64Bit())
 570         llvm_unreachable("CFProtection used on invalid architecture!");
 571       MCSection *Cur = OutStreamer->getCurrentSectionOnly();
 572       MCSection *Nt = MMI->getContext().getELFSection(
 573           ".note.gnu.property", ELF::SHT_NOTE, ELF::SHF_ALLOC);
 574       OutStreamer->SwitchSection(Nt);
 575
 576       // Emitting note header.
 577       int WordSize = TT.isArch64Bit() ? 8 : 4;
 578       EmitAlignment(WordSize == 4 ? Align(4) : Align(8));
 579       OutStreamer->EmitIntValue(4, 4 /*size*/); // data size for "GNU\0"
 580       OutStreamer->EmitIntValue(8 + WordSize, 4 /*size*/); // Elf_Prop size
 581       OutStreamer->EmitIntValue(ELF::NT_GNU_PROPERTY_TYPE_0, 4 /*size*/);
 582       OutStreamer->EmitBytes(StringRef("GNU", 4)); // note name
 583
 584       // Emitting an Elf_Prop for the CET properties.
 585       OutStreamer->EmitIntValue(ELF::GNU_PROPERTY_X86_FEATURE_1_AND, 4);
 586       OutStreamer->EmitIntValue(4, 4);               // data size
 587       OutStreamer->EmitIntValue(FeatureFlagsAnd, 4); // data
 588       EmitAlignment(WordSize == 4 ? Align(4) : Align(8)); // padding
 589
 590       OutStreamer->endSection(Nt);
 591       OutStreamer->SwitchSection(Cur);
 592     }
 593   }
 594
 595   if (TT.isOSBinFormatMachO())
 596     OutStreamer->SwitchSection(getObjFileLowering().getTextSection());
 597
 598   if (TT.isOSBinFormatCOFF()) {
 599     // Emit an absolute @feat.00 symbol.  This appears to be some kind of
 600     // compiler features bitfield read by link.exe.
 601     MCSymbol *S = MMI->getContext().getOrCreateSymbol(StringRef("@feat.00"));
 602     OutStreamer->BeginCOFFSymbolDef(S);
 603     OutStreamer->EmitCOFFSymbolStorageClass(COFF::IMAGE_SYM_CLASS_STATIC);
 604     OutStreamer->EmitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_NULL);
 605     OutStreamer->EndCOFFSymbolDef();
 606     int64_t Feat00Flags = 0;
 607
 608     if (TT.getArch() == Triple::x86) {
 609       // According to the PE-COFF spec, the LSB of this value marks the object
 610       // for "registered SEH".  This means that all SEH handler entry points
 611       // must be registered in .sxdata.  Use of any unregistered handlers will
 612       // cause the process to terminate immediately.  LLVM does not know how to
 613       // register any SEH handlers, so its object files should be safe.
 614       Feat00Flags |= 1;
 615     }
 616
 617     if (M.getModuleFlag("cfguardtable"))
 618       Feat00Flags |= 0x800; // Object is CFG-aware.
 619
 620     OutStreamer->EmitSymbolAttribute(S, MCSA_Global);
 621     OutStreamer->EmitAssignment(
 622         S, MCConstantExpr::create(Feat00Flags, MMI->getContext()));
 623   }
 624   OutStreamer->EmitSyntaxDirective();
 625
 626   // If this is not inline asm and we're in 16-bit
 627   // mode prefix assembly with .code16.
 628   bool is16 = TT.getEnvironment() == Triple::CODE16;
 629   if (M.getModuleInlineAsm().empty() && is16)
 630     OutStreamer->EmitAssemblerFlag(MCAF_Code16);
 631 }
 632
 633 static void
 634 emitNonLazySymbolPointer(MCStreamer &OutStreamer, MCSymbol *StubLabel,
 635                          MachineModuleInfoImpl::StubValueTy &MCSym) {
 636   // L_foo$stub:
 637   OutStreamer.EmitLabel(StubLabel);
 638   //   .indirect_symbol _foo
 639   OutStreamer.EmitSymbolAttribute(MCSym.getPointer(), MCSA_IndirectSymbol);
 640
 641   if (MCSym.getInt())
 642     // External to current translation unit.
 643     OutStreamer.EmitIntValue(0, 4/*size*/);
 644   else
 645     // Internal to current translation unit.
 646     //
 647     // When we place the LSDA into the TEXT section, the type info
 648     // pointers need to be indirect and pc-rel. We accomplish this by
 649     // using NLPs; however, sometimes the types are local to the file.
 650     // We need to fill in the value for the NLP in those cases.
 651     OutStreamer.EmitValue(
 652         MCSymbolRefExpr::create(MCSym.getPointer(), OutStreamer.getContext()),
 653         4 /*size*/);
 654 }
 655
 656 static void emitNonLazyStubs(MachineModuleInfo *MMI, MCStreamer &OutStreamer) {
 657
 658   MachineModuleInfoMachO &MMIMacho =
 659       MMI->getObjFileInfo<MachineModuleInfoMachO>();
 660
 661   // Output stubs for dynamically-linked functions.
 662   MachineModuleInfoMachO::SymbolListTy Stubs;
 663
 664   // Output stubs for external and common global variables.
 665   Stubs = MMIMacho.GetGVStubList();
 666   if (!Stubs.empty()) {
 667     OutStreamer.SwitchSection(MMI->getContext().getMachOSection(
 668         "__IMPORT", "__pointers", MachO::S_NON_LAZY_SYMBOL_POINTERS,
 669         SectionKind::getMetadata()));
 670
 671     for (auto &Stub : Stubs)
 672       emitNonLazySymbolPointer(OutStreamer, Stub.first, Stub.second);
 673
 674     Stubs.clear();
 675     OutStreamer.AddBlankLine();
 676   }
 677 }
 678
 679 void X86AsmPrinter::EmitEndOfAsmFile(Module &M) {
 680   const Triple &TT = TM.getTargetTriple();
 681
 682   if (TT.isOSBinFormatMachO()) {
 683     // Mach-O uses non-lazy symbol stubs to encode per-TU information into
 684     // global table for symbol lookup.
 685     emitNonLazyStubs(MMI, *OutStreamer);
 686
 687     // Emit stack and fault map information.
 688     emitStackMaps(SM);
 689     FM.serializeToFaultMapSection();
 690
 691     // This flag tells the linker that no global symbols contain code that fall
 692     // through to other global symbols (e.g. an implementation of multiple entry
 693     // points). If this doesn't occur, the linker can safely perform dead code
 694     // stripping. Since LLVM never generates code that does this, it is always
 695     // safe to set.
 696     OutStreamer->EmitAssemblerFlag(MCAF_SubsectionsViaSymbols);
 697   } else if (TT.isOSBinFormatCOFF()) {
 698     if (MMI->usesMSVCFloatingPoint()) {
 699       // In Windows' libcmt.lib, there is a file which is linked in only if the
 700       // symbol _fltused is referenced. Linking this in causes some
 701       // side-effects:
 702       //
 703       // 1. For x86-32, it will set the x87 rounding mode to 53-bit instead of
 704       // 64-bit mantissas at program start.
 705       //
 706       // 2. It links in support routines for floating-point in scanf and printf.
 707       //
 708       // MSVC emits an undefined reference to _fltused when there are any
 709       // floating point operations in the program (including calls). A program
 710       // that only has: `scanf("%f", &global_float);` may fail to trigger this,
 711       // but oh well...that's a documented issue.
 712       StringRef SymbolName =
 713           (TT.getArch() == Triple::x86) ? "__fltused" : "_fltused";
 714       MCSymbol *S = MMI->getContext().getOrCreateSymbol(SymbolName);
 715       OutStreamer->EmitSymbolAttribute(S, MCSA_Global);
 716       return;
 717     }
 718     emitStackMaps(SM);
 719   } else if (TT.isOSBinFormatELF()) {
 720     emitStackMaps(SM);
 721     FM.serializeToFaultMapSection();
 722   }
 723 }
 724
 725 //===----------------------------------------------------------------------===//
 726 // Target Registry Stuff
 727 //===----------------------------------------------------------------------===//
 728
 729 // Force static initialization.
 730 extern "C" void LLVMInitializeX86AsmPrinter() {
 731   RegisterAsmPrinter<X86AsmPrinter> X(getTheX86_32Target());
 732   RegisterAsmPrinter<X86AsmPrinter> Y(getTheX86_64Target());
 733 }