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 "InstPrinter/X86ATTInstPrinter.h"
  16 #include "MCTargetDesc/X86BaseInfo.h"
  17 #include "MCTargetDesc/X86TargetStreamer.h"
  18 #include "X86InstrInfo.h"
  19 #include "X86MachineFunctionInfo.h"
  20 #include "llvm/BinaryFormat/COFF.h"
  21 #include "llvm/BinaryFormat/ELF.h"
  22 #include "llvm/CodeGen/MachineConstantPool.h"
  23 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
  24 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
  25 #include "llvm/IR/DerivedTypes.h"
  26 #include "llvm/IR/Mangler.h"
  27 #include "llvm/IR/Module.h"
  28 #include "llvm/IR/Type.h"
  29 #include "llvm/MC/MCCodeEmitter.h"
  30 #include "llvm/MC/MCContext.h"
  31 #include "llvm/MC/MCExpr.h"
  32 #include "llvm/MC/MCSectionCOFF.h"
  33 #include "llvm/MC/MCSectionELF.h"
  34 #include "llvm/MC/MCSectionMachO.h"
  35 #include "llvm/MC/MCStreamer.h"
  36 #include "llvm/MC/MCSymbol.h"
  37 #include "llvm/Support/Debug.h"
  38 #include "llvm/Support/ErrorHandling.h"
  39 #include "llvm/Support/MachineValueType.h"
  40 #include "llvm/Support/TargetRegistry.h"
  41 using namespace llvm;
  42
  43 X86AsmPrinter::X86AsmPrinter(TargetMachine &TM,
  44                              std::unique_ptr<MCStreamer> Streamer)
  45     : AsmPrinter(TM, std::move(Streamer)), SM(*this), FM(*this) {}
  46
  47 //===----------------------------------------------------------------------===//
  48 // Primitive Helper Functions.
  49 //===----------------------------------------------------------------------===//
  50
  51 /// runOnMachineFunction - Emit the function body.
  52 ///
  53 bool X86AsmPrinter::runOnMachineFunction(MachineFunction &MF) {
  54   Subtarget = &MF.getSubtarget<X86Subtarget>();
  55
  56   SMShadowTracker.startFunction(MF);
  57   CodeEmitter.reset(TM.getTarget().createMCCodeEmitter(
  58       *Subtarget->getInstrInfo(), *Subtarget->getRegisterInfo(),
  59       MF.getContext()));
  60
  61   EmitFPOData =
  62       Subtarget->isTargetWin32() && MF.getMMI().getModule()->getCodeViewFlag();
  63
  64   SetupMachineFunction(MF);
  65
  66   if (Subtarget->isTargetCOFF()) {
  67     bool Local = MF.getFunction().hasLocalLinkage();
  68     OutStreamer->BeginCOFFSymbolDef(CurrentFnSym);
  69     OutStreamer->EmitCOFFSymbolStorageClass(
  70         Local ? COFF::IMAGE_SYM_CLASS_STATIC : COFF::IMAGE_SYM_CLASS_EXTERNAL);
  71     OutStreamer->EmitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_FUNCTION
  72                                                << COFF::SCT_COMPLEX_TYPE_SHIFT);
  73     OutStreamer->EndCOFFSymbolDef();
  74   }
  75
  76   // Emit the rest of the function body.
  77   EmitFunctionBody();
  78
  79   // Emit the XRay table for this function.
  80   emitXRayTable();
  81
  82   EmitFPOData = false;
  83
  84   // We didn't modify anything.
  85   return false;
  86 }
  87
  88 void X86AsmPrinter::EmitFunctionBodyStart() {
  89   if (EmitFPOData) {
  90     if (auto *XTS =
  91         static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer()))
  92       XTS->emitFPOProc(
  93           CurrentFnSym,
  94           MF->getInfo<X86MachineFunctionInfo>()->getArgumentStackSize());
  95   }
  96 }
  97
  98 void X86AsmPrinter::EmitFunctionBodyEnd() {
  99   if (EmitFPOData) {
 100     if (auto *XTS =
 101             static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer()))
 102       XTS->emitFPOEndProc();
 103   }
 104 }
 105
 106 /// printSymbolOperand - Print a raw symbol reference operand.  This handles
 107 /// jump tables, constant pools, global address and external symbols, all of
 108 /// which print to a label with various suffixes for relocation types etc.
 109 static void printSymbolOperand(X86AsmPrinter &P, const MachineOperand &MO,
 110                                raw_ostream &O) {
 111   switch (MO.getType()) {
 112   default: llvm_unreachable("unknown symbol type!");
 113   case MachineOperand::MO_ConstantPoolIndex:
 114     P.GetCPISymbol(MO.getIndex())->print(O, P.MAI);
 115     P.printOffset(MO.getOffset(), O);
 116     break;
 117   case MachineOperand::MO_GlobalAddress: {
 118     const GlobalValue *GV = MO.getGlobal();
 119
 120     MCSymbol *GVSym;
 121     if (MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY ||
 122         MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY_PIC_BASE)
 123       GVSym = P.getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
 124     else
 125       GVSym = P.getSymbol(GV);
 126
 127     // Handle dllimport linkage.
 128     if (MO.getTargetFlags() == X86II::MO_DLLIMPORT)
 129       GVSym =
 130           P.OutContext.getOrCreateSymbol(Twine("__imp_") + GVSym->getName());
 131     else if (MO.getTargetFlags() == X86II::MO_COFFSTUB)
 132       GVSym =
 133           P.OutContext.getOrCreateSymbol(Twine(".refptr.") + GVSym->getName());
 134
 135     if (MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY ||
 136         MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY_PIC_BASE) {
 137       MCSymbol *Sym = P.getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
 138       MachineModuleInfoImpl::StubValueTy &StubSym =
 139           P.MMI->getObjFileInfo<MachineModuleInfoMachO>().getGVStubEntry(Sym);
 140       if (!StubSym.getPointer())
 141         StubSym = MachineModuleInfoImpl::
 142           StubValueTy(P.getSymbol(GV), !GV->hasInternalLinkage());
 143     }
 144
 145     // If the name begins with a dollar-sign, enclose it in parens.  We do this
 146     // to avoid having it look like an integer immediate to the assembler.
 147     if (GVSym->getName()[0] != '$')
 148       GVSym->print(O, P.MAI);
 149     else {
 150       O << '(';
 151       GVSym->print(O, P.MAI);
 152       O << ')';
 153     }
 154     P.printOffset(MO.getOffset(), O);
 155     break;
 156   }
 157   }
 158
 159   switch (MO.getTargetFlags()) {
 160   default:
 161     llvm_unreachable("Unknown target flag on GV operand");
 162   case X86II::MO_NO_FLAG:    // No flag.
 163     break;
 164   case X86II::MO_DARWIN_NONLAZY:
 165   case X86II::MO_DLLIMPORT:
 166   case X86II::MO_COFFSTUB:
 167     // These affect the name of the symbol, not any suffix.
 168     break;
 169   case X86II::MO_GOT_ABSOLUTE_ADDRESS:
 170     O << " + [.-";
 171     P.MF->getPICBaseSymbol()->print(O, P.MAI);
 172     O << ']';
 173     break;
 174   case X86II::MO_PIC_BASE_OFFSET:
 175   case X86II::MO_DARWIN_NONLAZY_PIC_BASE:
 176     O << '-';
 177     P.MF->getPICBaseSymbol()->print(O, P.MAI);
 178     break;
 179   case X86II::MO_TLSGD:     O << "@TLSGD";     break;
 180   case X86II::MO_TLSLD:     O << "@TLSLD";     break;
 181   case X86II::MO_TLSLDM:    O << "@TLSLDM";    break;
 182   case X86II::MO_GOTTPOFF:  O << "@GOTTPOFF";  break;
 183   case X86II::MO_INDNTPOFF: O << "@INDNTPOFF"; break;
 184   case X86II::MO_TPOFF:     O << "@TPOFF";     break;
 185   case X86II::MO_DTPOFF:    O << "@DTPOFF";    break;
 186   case X86II::MO_NTPOFF:    O << "@NTPOFF";    break;
 187   case X86II::MO_GOTNTPOFF: O << "@GOTNTPOFF"; break;
 188   case X86II::MO_GOTPCREL:  O << "@GOTPCREL";  break;
 189   case X86II::MO_GOT:       O << "@GOT";       break;
 190   case X86II::MO_GOTOFF:    O << "@GOTOFF";    break;
 191   case X86II::MO_PLT:       O << "@PLT";       break;
 192   case X86II::MO_TLVP:      O << "@TLVP";      break;
 193   case X86II::MO_TLVP_PIC_BASE:
 194     O << "@TLVP" << '-';
 195     P.MF->getPICBaseSymbol()->print(O, P.MAI);
 196     break;
 197   case X86II::MO_SECREL:    O << "@SECREL32";  break;
 198   }
 199 }
 200
 201 static void printOperand(X86AsmPrinter &P, const MachineInstr *MI,
 202                          unsigned OpNo, raw_ostream &O,
 203                          const char *Modifier = nullptr, unsigned AsmVariant = 0);
 204
 205 /// printPCRelImm - This is used to print an immediate value that ends up
 206 /// being encoded as a pc-relative value.  These print slightly differently, for
 207 /// example, a $ is not emitted.
 208 static void printPCRelImm(X86AsmPrinter &P, const MachineInstr *MI,
 209                           unsigned OpNo, raw_ostream &O) {
 210   const MachineOperand &MO = MI->getOperand(OpNo);
 211   switch (MO.getType()) {
 212   default: llvm_unreachable("Unknown pcrel immediate operand");
 213   case MachineOperand::MO_Register:
 214     // pc-relativeness was handled when computing the value in the reg.
 215     printOperand(P, MI, OpNo, O);
 216     return;
 217   case MachineOperand::MO_Immediate:
 218     O << MO.getImm();
 219     return;
 220   case MachineOperand::MO_GlobalAddress:
 221     printSymbolOperand(P, MO, O);
 222     return;
 223   }
 224 }
 225
 226 static void printOperand(X86AsmPrinter &P, const MachineInstr *MI,
 227                          unsigned OpNo, raw_ostream &O, const char *Modifier,
 228                          unsigned AsmVariant) {
 229   const MachineOperand &MO = MI->getOperand(OpNo);
 230   switch (MO.getType()) {
 231   default: llvm_unreachable("unknown operand type!");
 232   case MachineOperand::MO_Register: {
 233     // FIXME: Enumerating AsmVariant, so we can remove magic number.
 234     if (AsmVariant == 0) O << '%';
 235     unsigned Reg = MO.getReg();
 236     if (Modifier && strncmp(Modifier, "subreg", strlen("subreg")) == 0) {
 237       unsigned Size = (strcmp(Modifier+6,"64") == 0) ? 64 :
 238                       (strcmp(Modifier+6,"32") == 0) ? 32 :
 239                       (strcmp(Modifier+6,"16") == 0) ? 16 : 8;
 240       Reg = getX86SubSuperRegister(Reg, Size);
 241     }
 242     O << X86ATTInstPrinter::getRegisterName(Reg);
 243     return;
 244   }
 245
 246   case MachineOperand::MO_Immediate:
 247     if (AsmVariant == 0) O << '$';
 248     O << MO.getImm();
 249     return;
 250
 251   case MachineOperand::MO_GlobalAddress: {
 252     if (AsmVariant == 0) O << '$';
 253     printSymbolOperand(P, MO, O);
 254     break;
 255   }
 256   case MachineOperand::MO_BlockAddress: {
 257     MCSymbol *Sym = P.GetBlockAddressSymbol(MO.getBlockAddress());
 258     Sym->print(O, P.MAI);
 259     break;
 260   }
 261   }
 262 }
 263
 264 static void printLeaMemReference(X86AsmPrinter &P, const MachineInstr *MI,
 265                                  unsigned Op, raw_ostream &O,
 266                                  const char *Modifier = nullptr) {
 267   const MachineOperand &BaseReg  = MI->getOperand(Op+X86::AddrBaseReg);
 268   const MachineOperand &IndexReg = MI->getOperand(Op+X86::AddrIndexReg);
 269   const MachineOperand &DispSpec = MI->getOperand(Op+X86::AddrDisp);
 270
 271   // If we really don't want to print out (rip), don't.
 272   bool HasBaseReg = BaseReg.getReg() != 0;
 273   if (HasBaseReg && Modifier && !strcmp(Modifier, "no-rip") &&
 274       BaseReg.getReg() == X86::RIP)
 275     HasBaseReg = false;
 276
 277   // HasParenPart - True if we will print out the () part of the mem ref.
 278   bool HasParenPart = IndexReg.getReg() || HasBaseReg;
 279
 280   switch (DispSpec.getType()) {
 281   default:
 282     llvm_unreachable("unknown operand type!");
 283   case MachineOperand::MO_Immediate: {
 284     int DispVal = DispSpec.getImm();
 285     if (DispVal || !HasParenPart)
 286       O << DispVal;
 287     break;
 288   }
 289   case MachineOperand::MO_GlobalAddress:
 290   case MachineOperand::MO_ConstantPoolIndex:
 291     printSymbolOperand(P, DispSpec, O);
 292   }
 293
 294   if (Modifier && strcmp(Modifier, "H") == 0)
 295     O << "+8";
 296
 297   if (HasParenPart) {
 298     assert(IndexReg.getReg() != X86::ESP &&
 299            "X86 doesn't allow scaling by ESP");
 300
 301     O << '(';
 302     if (HasBaseReg)
 303       printOperand(P, MI, Op+X86::AddrBaseReg, O, Modifier);
 304
 305     if (IndexReg.getReg()) {
 306       O << ',';
 307       printOperand(P, MI, Op+X86::AddrIndexReg, O, Modifier);
 308       unsigned ScaleVal = MI->getOperand(Op+X86::AddrScaleAmt).getImm();
 309       if (ScaleVal != 1)
 310         O << ',' << ScaleVal;
 311     }
 312     O << ')';
 313   }
 314 }
 315
 316 static void printMemReference(X86AsmPrinter &P, const MachineInstr *MI,
 317                               unsigned Op, raw_ostream &O,
 318                               const char *Modifier = nullptr) {
 319   assert(isMem(*MI, Op) && "Invalid memory reference!");
 320   const MachineOperand &Segment = MI->getOperand(Op+X86::AddrSegmentReg);
 321   if (Segment.getReg()) {
 322     printOperand(P, MI, Op+X86::AddrSegmentReg, O, Modifier);
 323     O << ':';
 324   }
 325   printLeaMemReference(P, MI, Op, O, Modifier);
 326 }
 327
 328 static void printIntelMemReference(X86AsmPrinter &P, const MachineInstr *MI,
 329                                    unsigned Op, raw_ostream &O,
 330                                    const char *Modifier = nullptr,
 331                                    unsigned AsmVariant = 1) {
 332   const MachineOperand &BaseReg  = MI->getOperand(Op+X86::AddrBaseReg);
 333   unsigned ScaleVal = MI->getOperand(Op+X86::AddrScaleAmt).getImm();
 334   const MachineOperand &IndexReg = MI->getOperand(Op+X86::AddrIndexReg);
 335   const MachineOperand &DispSpec = MI->getOperand(Op+X86::AddrDisp);
 336   const MachineOperand &SegReg   = MI->getOperand(Op+X86::AddrSegmentReg);
 337
 338   // If this has a segment register, print it.
 339   if (SegReg.getReg()) {
 340     printOperand(P, MI, Op+X86::AddrSegmentReg, O, Modifier, AsmVariant);
 341     O << ':';
 342   }
 343
 344   O << '[';
 345
 346   bool NeedPlus = false;
 347   if (BaseReg.getReg()) {
 348     printOperand(P, MI, Op+X86::AddrBaseReg, O, Modifier, AsmVariant);
 349     NeedPlus = true;
 350   }
 351
 352   if (IndexReg.getReg()) {
 353     if (NeedPlus) O << " + ";
 354     if (ScaleVal != 1)
 355       O << ScaleVal << '*';
 356     printOperand(P, MI, Op+X86::AddrIndexReg, O, Modifier, AsmVariant);
 357     NeedPlus = true;
 358   }
 359
 360   if (!DispSpec.isImm()) {
 361     if (NeedPlus) O << " + ";
 362     printOperand(P, MI, Op+X86::AddrDisp, O, Modifier, AsmVariant);
 363   } else {
 364     int64_t DispVal = DispSpec.getImm();
 365     if (DispVal || (!IndexReg.getReg() && !BaseReg.getReg())) {
 366       if (NeedPlus) {
 367         if (DispVal > 0)
 368           O << " + ";
 369         else {
 370           O << " - ";
 371           DispVal = -DispVal;
 372         }
 373       }
 374       O << DispVal;
 375     }
 376   }
 377   O << ']';
 378 }
 379
 380 static bool printAsmMRegister(X86AsmPrinter &P, const MachineOperand &MO,
 381                               char Mode, raw_ostream &O) {
 382   unsigned Reg = MO.getReg();
 383   bool EmitPercent = true;
 384
 385   if (!X86::GR8RegClass.contains(Reg) &&
 386       !X86::GR16RegClass.contains(Reg) &&
 387       !X86::GR32RegClass.contains(Reg) &&
 388       !X86::GR64RegClass.contains(Reg))
 389     return true;
 390
 391   switch (Mode) {
 392   default: return true;  // Unknown mode.
 393   case 'b': // Print QImode register
 394     Reg = getX86SubSuperRegister(Reg, 8);
 395     break;
 396   case 'h': // Print QImode high register
 397     Reg = getX86SubSuperRegister(Reg, 8, true);
 398     break;
 399   case 'w': // Print HImode register
 400     Reg = getX86SubSuperRegister(Reg, 16);
 401     break;
 402   case 'k': // Print SImode register
 403     Reg = getX86SubSuperRegister(Reg, 32);
 404     break;
 405   case 'V':
 406     EmitPercent = false;
 407     LLVM_FALLTHROUGH;
 408   case 'q':
 409     // Print 64-bit register names if 64-bit integer registers are available.
 410     // Otherwise, print 32-bit register names.
 411     Reg = getX86SubSuperRegister(Reg, P.getSubtarget().is64Bit() ? 64 : 32);
 412     break;
 413   }
 414
 415   if (EmitPercent)
 416     O << '%';
 417
 418   O << X86ATTInstPrinter::getRegisterName(Reg);
 419   return false;
 420 }
 421
 422 /// PrintAsmOperand - Print out an operand for an inline asm expression.
 423 ///
 424 bool X86AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
 425                                     unsigned AsmVariant,
 426                                     const char *ExtraCode, raw_ostream &O) {
 427   // Does this asm operand have a single letter operand modifier?
 428   if (ExtraCode && ExtraCode[0]) {
 429     if (ExtraCode[1] != 0) return true; // Unknown modifier.
 430
 431     const MachineOperand &MO = MI->getOperand(OpNo);
 432
 433     switch (ExtraCode[0]) {
 434     default:
 435       // See if this is a generic print operand
 436       return AsmPrinter::PrintAsmOperand(MI, OpNo, AsmVariant, ExtraCode, O);
 437     case 'a': // This is an address.  Currently only 'i' and 'r' are expected.
 438       switch (MO.getType()) {
 439       default:
 440         return true;
 441       case MachineOperand::MO_Immediate:
 442         O << MO.getImm();
 443         return false;
 444       case MachineOperand::MO_ConstantPoolIndex:
 445       case MachineOperand::MO_JumpTableIndex:
 446       case MachineOperand::MO_ExternalSymbol:
 447         llvm_unreachable("unexpected operand type!");
 448       case MachineOperand::MO_GlobalAddress:
 449         printSymbolOperand(*this, MO, O);
 450         if (Subtarget->isPICStyleRIPRel())
 451           O << "(%rip)";
 452         return false;
 453       case MachineOperand::MO_Register:
 454         O << '(';
 455         printOperand(*this, MI, OpNo, O);
 456         O << ')';
 457         return false;
 458       }
 459
 460     case 'c': // Don't print "$" before a global var name or constant.
 461       switch (MO.getType()) {
 462       default:
 463         printOperand(*this, MI, OpNo, O);
 464         break;
 465       case MachineOperand::MO_Immediate:
 466         O << MO.getImm();
 467         break;
 468       case MachineOperand::MO_ConstantPoolIndex:
 469       case MachineOperand::MO_JumpTableIndex:
 470       case MachineOperand::MO_ExternalSymbol:
 471         llvm_unreachable("unexpected operand type!");
 472       case MachineOperand::MO_GlobalAddress:
 473         printSymbolOperand(*this, MO, O);
 474         break;
 475       }
 476       return false;
 477
 478     case 'A': // Print '*' before a register (it must be a register)
 479       if (MO.isReg()) {
 480         O << '*';
 481         printOperand(*this, MI, OpNo, O);
 482         return false;
 483       }
 484       return true;
 485
 486     case 'b': // Print QImode register
 487     case 'h': // Print QImode high register
 488     case 'w': // Print HImode register
 489     case 'k': // Print SImode register
 490     case 'q': // Print DImode register
 491     case 'V': // Print native register without '%'
 492       if (MO.isReg())
 493         return printAsmMRegister(*this, MO, ExtraCode[0], O);
 494       printOperand(*this, MI, OpNo, O);
 495       return false;
 496
 497     case 'P': // This is the operand of a call, treat specially.
 498       printPCRelImm(*this, MI, OpNo, O);
 499       return false;
 500
 501     case 'n': // Negate the immediate or print a '-' before the operand.
 502       // Note: this is a temporary solution. It should be handled target
 503       // independently as part of the 'MC' work.
 504       if (MO.isImm()) {
 505         O << -MO.getImm();
 506         return false;
 507       }
 508       O << '-';
 509     }
 510   }
 511
 512   printOperand(*this, MI, OpNo, O, /*Modifier*/ nullptr, AsmVariant);
 513   return false;
 514 }
 515
 516 bool X86AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
 517                                           unsigned OpNo, unsigned AsmVariant,
 518                                           const char *ExtraCode,
 519                                           raw_ostream &O) {
 520   if (AsmVariant) {
 521     printIntelMemReference(*this, MI, OpNo, O);
 522     return false;
 523   }
 524
 525   if (ExtraCode && ExtraCode[0]) {
 526     if (ExtraCode[1] != 0) return true; // Unknown modifier.
 527
 528     switch (ExtraCode[0]) {
 529     default: return true;  // Unknown modifier.
 530     case 'b': // Print QImode register
 531     case 'h': // Print QImode high register
 532     case 'w': // Print HImode register
 533     case 'k': // Print SImode register
 534     case 'q': // Print SImode register
 535       // These only apply to registers, ignore on mem.
 536       break;
 537     case 'H':
 538       printMemReference(*this, MI, OpNo, O, "H");
 539       return false;
 540     case 'P': // Don't print @PLT, but do print as memory.
 541       printMemReference(*this, MI, OpNo, O, "no-rip");
 542       return false;
 543     }
 544   }
 545   printMemReference(*this, MI, OpNo, O);
 546   return false;
 547 }
 548
 549 void X86AsmPrinter::EmitStartOfAsmFile(Module &M) {
 550   const Triple &TT = TM.getTargetTriple();
 551
 552   if (TT.isOSBinFormatELF()) {
 553     // Assemble feature flags that may require creation of a note section.
 554     unsigned FeatureFlagsAnd = 0;
 555     if (M.getModuleFlag("cf-protection-branch"))
 556       FeatureFlagsAnd |= ELF::GNU_PROPERTY_X86_FEATURE_1_IBT;
 557     if (M.getModuleFlag("cf-protection-return"))
 558       FeatureFlagsAnd |= ELF::GNU_PROPERTY_X86_FEATURE_1_SHSTK;
 559
 560     if (FeatureFlagsAnd) {
 561       // Emit a .note.gnu.property section with the flags.
 562       if (!TT.isArch32Bit() && !TT.isArch64Bit())
 563         llvm_unreachable("CFProtection used on invalid architecture!");
 564       MCSection *Cur = OutStreamer->getCurrentSectionOnly();
 565       MCSection *Nt = MMI->getContext().getELFSection(
 566           ".note.gnu.property", ELF::SHT_NOTE, ELF::SHF_ALLOC);
 567       OutStreamer->SwitchSection(Nt);
 568
 569       // Emitting note header.
 570       int WordSize = TT.isArch64Bit() ? 8 : 4;
 571       EmitAlignment(WordSize == 4 ? 2 : 3);
 572       OutStreamer->EmitIntValue(4, 4 /*size*/); // data size for "GNU\0"
 573       OutStreamer->EmitIntValue(8 + WordSize, 4 /*size*/); // Elf_Prop size
 574       OutStreamer->EmitIntValue(ELF::NT_GNU_PROPERTY_TYPE_0, 4 /*size*/);
 575       OutStreamer->EmitBytes(StringRef("GNU", 4)); // note name
 576
 577       // Emitting an Elf_Prop for the CET properties.
 578       OutStreamer->EmitIntValue(ELF::GNU_PROPERTY_X86_FEATURE_1_AND, 4);
 579       OutStreamer->EmitIntValue(4, 4);               // data size
 580       OutStreamer->EmitIntValue(FeatureFlagsAnd, 4); // data
 581       EmitAlignment(WordSize == 4 ? 2 : 3);          // padding
 582
 583       OutStreamer->endSection(Nt);
 584       OutStreamer->SwitchSection(Cur);
 585     }
 586   }
 587
 588   if (TT.isOSBinFormatMachO())
 589     OutStreamer->SwitchSection(getObjFileLowering().getTextSection());
 590
 591   if (TT.isOSBinFormatCOFF()) {
 592     // Emit an absolute @feat.00 symbol.  This appears to be some kind of
 593     // compiler features bitfield read by link.exe.
 594     MCSymbol *S = MMI->getContext().getOrCreateSymbol(StringRef("@feat.00"));
 595     OutStreamer->BeginCOFFSymbolDef(S);
 596     OutStreamer->EmitCOFFSymbolStorageClass(COFF::IMAGE_SYM_CLASS_STATIC);
 597     OutStreamer->EmitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_NULL);
 598     OutStreamer->EndCOFFSymbolDef();
 599     int64_t Feat00Flags = 0;
 600
 601     if (TT.getArch() == Triple::x86) {
 602       // According to the PE-COFF spec, the LSB of this value marks the object
 603       // for "registered SEH".  This means that all SEH handler entry points
 604       // must be registered in .sxdata.  Use of any unregistered handlers will
 605       // cause the process to terminate immediately.  LLVM does not know how to
 606       // register any SEH handlers, so its object files should be safe.
 607       Feat00Flags |= 1;
 608     }
 609
 610     if (M.getModuleFlag("cfguardtable"))
 611       Feat00Flags |= 0x800; // Object is CFG-aware.
 612
 613     OutStreamer->EmitSymbolAttribute(S, MCSA_Global);
 614     OutStreamer->EmitAssignment(
 615         S, MCConstantExpr::create(Feat00Flags, MMI->getContext()));
 616   }
 617   OutStreamer->EmitSyntaxDirective();
 618
 619   // If this is not inline asm and we're in 16-bit
 620   // mode prefix assembly with .code16.
 621   bool is16 = TT.getEnvironment() == Triple::CODE16;
 622   if (M.getModuleInlineAsm().empty() && is16)
 623     OutStreamer->EmitAssemblerFlag(MCAF_Code16);
 624 }
 625
 626 static void
 627 emitNonLazySymbolPointer(MCStreamer &OutStreamer, MCSymbol *StubLabel,
 628                          MachineModuleInfoImpl::StubValueTy &MCSym) {
 629   // L_foo$stub:
 630   OutStreamer.EmitLabel(StubLabel);
 631   //   .indirect_symbol _foo
 632   OutStreamer.EmitSymbolAttribute(MCSym.getPointer(), MCSA_IndirectSymbol);
 633
 634   if (MCSym.getInt())
 635     // External to current translation unit.
 636     OutStreamer.EmitIntValue(0, 4/*size*/);
 637   else
 638     // Internal to current translation unit.
 639     //
 640     // When we place the LSDA into the TEXT section, the type info
 641     // pointers need to be indirect and pc-rel. We accomplish this by
 642     // using NLPs; however, sometimes the types are local to the file.
 643     // We need to fill in the value for the NLP in those cases.
 644     OutStreamer.EmitValue(
 645         MCSymbolRefExpr::create(MCSym.getPointer(), OutStreamer.getContext()),
 646         4 /*size*/);
 647 }
 648
 649 static void emitNonLazyStubs(MachineModuleInfo *MMI, MCStreamer &OutStreamer) {
 650
 651   MachineModuleInfoMachO &MMIMacho =
 652       MMI->getObjFileInfo<MachineModuleInfoMachO>();
 653
 654   // Output stubs for dynamically-linked functions.
 655   MachineModuleInfoMachO::SymbolListTy Stubs;
 656
 657   // Output stubs for external and common global variables.
 658   Stubs = MMIMacho.GetGVStubList();
 659   if (!Stubs.empty()) {
 660     OutStreamer.SwitchSection(MMI->getContext().getMachOSection(
 661         "__IMPORT", "__pointers", MachO::S_NON_LAZY_SYMBOL_POINTERS,
 662         SectionKind::getMetadata()));
 663
 664     for (auto &Stub : Stubs)
 665       emitNonLazySymbolPointer(OutStreamer, Stub.first, Stub.second);
 666
 667     Stubs.clear();
 668     OutStreamer.AddBlankLine();
 669   }
 670 }
 671
 672 void X86AsmPrinter::EmitEndOfAsmFile(Module &M) {
 673   const Triple &TT = TM.getTargetTriple();
 674
 675   if (TT.isOSBinFormatMachO()) {
 676     // Mach-O uses non-lazy symbol stubs to encode per-TU information into
 677     // global table for symbol lookup.
 678     emitNonLazyStubs(MMI, *OutStreamer);
 679
 680     // Emit stack and fault map information.
 681     emitStackMaps(SM);
 682     FM.serializeToFaultMapSection();
 683
 684     // This flag tells the linker that no global symbols contain code that fall
 685     // through to other global symbols (e.g. an implementation of multiple entry
 686     // points). If this doesn't occur, the linker can safely perform dead code
 687     // stripping. Since LLVM never generates code that does this, it is always
 688     // safe to set.
 689     OutStreamer->EmitAssemblerFlag(MCAF_SubsectionsViaSymbols);
 690   } else if (TT.isOSBinFormatCOFF()) {
 691     if (MMI->usesMSVCFloatingPoint()) {
 692       // In Windows' libcmt.lib, there is a file which is linked in only if the
 693       // symbol _fltused is referenced. Linking this in causes some
 694       // side-effects:
 695       //
 696       // 1. For x86-32, it will set the x87 rounding mode to 53-bit instead of
 697       // 64-bit mantissas at program start.
 698       //
 699       // 2. It links in support routines for floating-point in scanf and printf.
 700       //
 701       // MSVC emits an undefined reference to _fltused when there are any
 702       // floating point operations in the program (including calls). A program
 703       // that only has: `scanf("%f", &global_float);` may fail to trigger this,
 704       // but oh well...that's a documented issue.
 705       StringRef SymbolName =
 706           (TT.getArch() == Triple::x86) ? "__fltused" : "_fltused";
 707       MCSymbol *S = MMI->getContext().getOrCreateSymbol(SymbolName);
 708       OutStreamer->EmitSymbolAttribute(S, MCSA_Global);
 709       return;
 710     }
 711     emitStackMaps(SM);
 712   } else if (TT.isOSBinFormatELF()) {
 713     emitStackMaps(SM);
 714     FM.serializeToFaultMapSection();
 715   }
 716 }
 717
 718 //===----------------------------------------------------------------------===//
 719 // Target Registry Stuff
 720 //===----------------------------------------------------------------------===//
 721
 722 // Force static initialization.
 723 extern "C" void LLVMInitializeX86AsmPrinter() {
 724   RegisterAsmPrinter<X86AsmPrinter> X(getTheX86_32Target());
 725   RegisterAsmPrinter<X86AsmPrinter> Y(getTheX86_64Target());
 726 }