lib/MC/MCStreamer.cpp

   1 //===- lib/MC/MCStreamer.cpp - Streaming Machine Code Output --------------===//
   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 #include "llvm/MC/MCStreamer.h"
  10 #include "llvm/ADT/Optional.h"
  11 #include "llvm/ADT/SmallString.h"
  12 #include "llvm/ADT/StringRef.h"
  13 #include "llvm/ADT/Twine.h"
  14 #include "llvm/BinaryFormat/COFF.h"
  15 #include "llvm/MC/MCAsmBackend.h"
  16 #include "llvm/MC/MCAsmInfo.h"
  17 #include "llvm/MC/MCCodeView.h"
  18 #include "llvm/MC/MCContext.h"
  19 #include "llvm/MC/MCDwarf.h"
  20 #include "llvm/MC/MCExpr.h"
  21 #include "llvm/MC/MCInst.h"
  22 #include "llvm/MC/MCInstPrinter.h"
  23 #include "llvm/MC/MCObjectFileInfo.h"
  24 #include "llvm/MC/MCRegister.h"
  25 #include "llvm/MC/MCRegisterInfo.h"
  26 #include "llvm/MC/MCSection.h"
  27 #include "llvm/MC/MCSectionCOFF.h"
  28 #include "llvm/MC/MCSymbol.h"
  29 #include "llvm/MC/MCWin64EH.h"
  30 #include "llvm/MC/MCWinEH.h"
  31 #include "llvm/Support/Casting.h"
  32 #include "llvm/Support/ErrorHandling.h"
  33 #include "llvm/Support/LEB128.h"
  34 #include "llvm/Support/MathExtras.h"
  35 #include "llvm/Support/raw_ostream.h"
  36 #include <cassert>
  37 #include <cstdint>
  38 #include <cstdlib>
  39 #include <utility>
  40
  41 using namespace llvm;
  42
  43 MCTargetStreamer::MCTargetStreamer(MCStreamer &S) : Streamer(S) {
  44   S.setTargetStreamer(this);
  45 }
  46
  47 // Pin the vtables to this file.
  48 MCTargetStreamer::~MCTargetStreamer() = default;
  49
  50 void MCTargetStreamer::emitLabel(MCSymbol *Symbol) {}
  51
  52 void MCTargetStreamer::finish() {}
  53
  54 void MCTargetStreamer::changeSection(const MCSection *CurSection,
  55                                      MCSection *Section,
  56                                      const MCExpr *Subsection,
  57                                      raw_ostream &OS) {
  58   Section->PrintSwitchToSection(
  59       *Streamer.getContext().getAsmInfo(),
  60       Streamer.getContext().getObjectFileInfo()->getTargetTriple(), OS,
  61       Subsection);
  62 }
  63
  64 void MCTargetStreamer::emitDwarfFileDirective(StringRef Directive) {
  65   Streamer.EmitRawText(Directive);
  66 }
  67
  68 void MCTargetStreamer::emitValue(const MCExpr *Value) {
  69   SmallString<128> Str;
  70   raw_svector_ostream OS(Str);
  71
  72   Value->print(OS, Streamer.getContext().getAsmInfo());
  73   Streamer.EmitRawText(OS.str());
  74 }
  75
  76 void MCTargetStreamer::emitRawBytes(StringRef Data) {
  77   const MCAsmInfo *MAI = Streamer.getContext().getAsmInfo();
  78   const char *Directive = MAI->getData8bitsDirective();
  79   for (const unsigned char C : Data.bytes()) {
  80     SmallString<128> Str;
  81     raw_svector_ostream OS(Str);
  82
  83     OS << Directive << (unsigned)C;
  84     Streamer.EmitRawText(OS.str());
  85   }
  86 }
  87
  88 void MCTargetStreamer::emitAssignment(MCSymbol *Symbol, const MCExpr *Value) {}
  89
  90 MCStreamer::MCStreamer(MCContext &Ctx)
  91     : Context(Ctx), CurrentWinFrameInfo(nullptr),
  92       UseAssemblerInfoForParsing(false) {
  93   SectionStack.push_back(std::pair<MCSectionSubPair, MCSectionSubPair>());
  94 }
  95
  96 MCStreamer::~MCStreamer() {}
  97
  98 void MCStreamer::reset() {
  99   DwarfFrameInfos.clear();
 100   CurrentWinFrameInfo = nullptr;
 101   WinFrameInfos.clear();
 102   SymbolOrdering.clear();
 103   SectionStack.clear();
 104   SectionStack.push_back(std::pair<MCSectionSubPair, MCSectionSubPair>());
 105 }
 106
 107 raw_ostream &MCStreamer::GetCommentOS() {
 108   // By default, discard comments.
 109   return nulls();
 110 }
 111
 112 unsigned MCStreamer::getNumFrameInfos() { return DwarfFrameInfos.size(); }
 113 ArrayRef<MCDwarfFrameInfo> MCStreamer::getDwarfFrameInfos() const {
 114   return DwarfFrameInfos;
 115 }
 116
 117 void MCStreamer::emitRawComment(const Twine &T, bool TabPrefix) {}
 118
 119 void MCStreamer::addExplicitComment(const Twine &T) {}
 120 void MCStreamer::emitExplicitComments() {}
 121
 122 void MCStreamer::generateCompactUnwindEncodings(MCAsmBackend *MAB) {
 123   for (auto &FI : DwarfFrameInfos)
 124     FI.CompactUnwindEncoding =
 125         (MAB ? MAB->generateCompactUnwindEncoding(FI.Instructions) : 0);
 126 }
 127
 128 /// EmitIntValue - Special case of EmitValue that avoids the client having to
 129 /// pass in a MCExpr for constant integers.
 130 void MCStreamer::EmitIntValue(uint64_t Value, unsigned Size) {
 131   assert(1 <= Size && Size <= 8 && "Invalid size");
 132   assert((isUIntN(8 * Size, Value) || isIntN(8 * Size, Value)) &&
 133          "Invalid size");
 134   char buf[8];
 135   const bool isLittleEndian = Context.getAsmInfo()->isLittleEndian();
 136   for (unsigned i = 0; i != Size; ++i) {
 137     unsigned index = isLittleEndian ? i : (Size - i - 1);
 138     buf[i] = uint8_t(Value >> (index * 8));
 139   }
 140   EmitBytes(StringRef(buf, Size));
 141 }
 142
 143 /// EmitULEB128IntValue - Special case of EmitULEB128Value that avoids the
 144 /// client having to pass in a MCExpr for constant integers.
 145 void MCStreamer::EmitULEB128IntValue(uint64_t Value, unsigned PadTo) {
 146   SmallString<128> Tmp;
 147   raw_svector_ostream OSE(Tmp);
 148   encodeULEB128(Value, OSE, PadTo);
 149   EmitBytes(OSE.str());
 150 }
 151
 152 /// EmitSLEB128IntValue - Special case of EmitSLEB128Value that avoids the
 153 /// client having to pass in a MCExpr for constant integers.
 154 void MCStreamer::EmitSLEB128IntValue(int64_t Value) {
 155   SmallString<128> Tmp;
 156   raw_svector_ostream OSE(Tmp);
 157   encodeSLEB128(Value, OSE);
 158   EmitBytes(OSE.str());
 159 }
 160
 161 void MCStreamer::EmitValue(const MCExpr *Value, unsigned Size, SMLoc Loc) {
 162   EmitValueImpl(Value, Size, Loc);
 163 }
 164
 165 void MCStreamer::EmitSymbolValue(const MCSymbol *Sym, unsigned Size,
 166                                  bool IsSectionRelative) {
 167   assert((!IsSectionRelative || Size == 4) &&
 168          "SectionRelative value requires 4-bytes");
 169
 170   if (!IsSectionRelative)
 171     EmitValueImpl(MCSymbolRefExpr::create(Sym, getContext()), Size);
 172   else
 173     EmitCOFFSecRel32(Sym, /*Offset=*/0);
 174 }
 175
 176 void MCStreamer::EmitDTPRel64Value(const MCExpr *Value) {
 177   report_fatal_error("unsupported directive in streamer");
 178 }
 179
 180 void MCStreamer::EmitDTPRel32Value(const MCExpr *Value) {
 181   report_fatal_error("unsupported directive in streamer");
 182 }
 183
 184 void MCStreamer::EmitTPRel64Value(const MCExpr *Value) {
 185   report_fatal_error("unsupported directive in streamer");
 186 }
 187
 188 void MCStreamer::EmitTPRel32Value(const MCExpr *Value) {
 189   report_fatal_error("unsupported directive in streamer");
 190 }
 191
 192 void MCStreamer::EmitGPRel64Value(const MCExpr *Value) {
 193   report_fatal_error("unsupported directive in streamer");
 194 }
 195
 196 void MCStreamer::EmitGPRel32Value(const MCExpr *Value) {
 197   report_fatal_error("unsupported directive in streamer");
 198 }
 199
 200 /// Emit NumBytes bytes worth of the value specified by FillValue.
 201 /// This implements directives such as '.space'.
 202 void MCStreamer::emitFill(uint64_t NumBytes, uint8_t FillValue) {
 203   emitFill(*MCConstantExpr::create(NumBytes, getContext()), FillValue);
 204 }
 205
 206 /// The implementation in this class just redirects to emitFill.
 207 void MCStreamer::EmitZeros(uint64_t NumBytes) {
 208   emitFill(NumBytes, 0);
 209 }
 210
 211 Expected<unsigned>
 212 MCStreamer::tryEmitDwarfFileDirective(unsigned FileNo, StringRef Directory,
 213                                       StringRef Filename,
 214                                       Optional<MD5::MD5Result> Checksum,
 215                                       Optional<StringRef> Source,
 216                                       unsigned CUID) {
 217   return getContext().getDwarfFile(Directory, Filename, FileNo, Checksum,
 218                                    Source, CUID);
 219 }
 220
 221 void MCStreamer::emitDwarfFile0Directive(StringRef Directory,
 222                                          StringRef Filename,
 223                                          Optional<MD5::MD5Result> Checksum,
 224                                          Optional<StringRef> Source,
 225                                          unsigned CUID) {
 226   getContext().setMCLineTableRootFile(CUID, Directory, Filename, Checksum,
 227                                       Source);
 228 }
 229
 230 void MCStreamer::EmitCFIBKeyFrame() {
 231   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 232   if (!CurFrame)
 233     return;
 234   CurFrame->IsBKeyFrame = true;
 235 }
 236
 237 void MCStreamer::EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
 238                                        unsigned Column, unsigned Flags,
 239                                        unsigned Isa,
 240                                        unsigned Discriminator,
 241                                        StringRef FileName) {
 242   getContext().setCurrentDwarfLoc(FileNo, Line, Column, Flags, Isa,
 243                                   Discriminator);
 244 }
 245
 246 MCSymbol *MCStreamer::getDwarfLineTableSymbol(unsigned CUID) {
 247   MCDwarfLineTable &Table = getContext().getMCDwarfLineTable(CUID);
 248   if (!Table.getLabel()) {
 249     StringRef Prefix = Context.getAsmInfo()->getPrivateGlobalPrefix();
 250     Table.setLabel(
 251         Context.getOrCreateSymbol(Prefix + "line_table_start" + Twine(CUID)));
 252   }
 253   return Table.getLabel();
 254 }
 255
 256 bool MCStreamer::hasUnfinishedDwarfFrameInfo() {
 257   return !DwarfFrameInfos.empty() && !DwarfFrameInfos.back().End;
 258 }
 259
 260 MCDwarfFrameInfo *MCStreamer::getCurrentDwarfFrameInfo() {
 261   if (!hasUnfinishedDwarfFrameInfo()) {
 262     getContext().reportError(SMLoc(), "this directive must appear between "
 263                                       ".cfi_startproc and .cfi_endproc "
 264                                       "directives");
 265     return nullptr;
 266   }
 267   return &DwarfFrameInfos.back();
 268 }
 269
 270 bool MCStreamer::EmitCVFileDirective(unsigned FileNo, StringRef Filename,
 271                                      ArrayRef<uint8_t> Checksum,
 272                                      unsigned ChecksumKind) {
 273   return getContext().getCVContext().addFile(*this, FileNo, Filename, Checksum,
 274                                              ChecksumKind);
 275 }
 276
 277 bool MCStreamer::EmitCVFuncIdDirective(unsigned FunctionId) {
 278   return getContext().getCVContext().recordFunctionId(FunctionId);
 279 }
 280
 281 bool MCStreamer::EmitCVInlineSiteIdDirective(unsigned FunctionId,
 282                                              unsigned IAFunc, unsigned IAFile,
 283                                              unsigned IALine, unsigned IACol,
 284                                              SMLoc Loc) {
 285   if (getContext().getCVContext().getCVFunctionInfo(IAFunc) == nullptr) {
 286     getContext().reportError(Loc, "parent function id not introduced by "
 287                                   ".cv_func_id or .cv_inline_site_id");
 288     return true;
 289   }
 290
 291   return getContext().getCVContext().recordInlinedCallSiteId(
 292       FunctionId, IAFunc, IAFile, IALine, IACol);
 293 }
 294
 295 void MCStreamer::EmitCVLocDirective(unsigned FunctionId, unsigned FileNo,
 296                                     unsigned Line, unsigned Column,
 297                                     bool PrologueEnd, bool IsStmt,
 298                                     StringRef FileName, SMLoc Loc) {}
 299
 300 bool MCStreamer::checkCVLocSection(unsigned FuncId, unsigned FileNo,
 301                                    SMLoc Loc) {
 302   CodeViewContext &CVC = getContext().getCVContext();
 303   MCCVFunctionInfo *FI = CVC.getCVFunctionInfo(FuncId);
 304   if (!FI) {
 305     getContext().reportError(
 306         Loc, "function id not introduced by .cv_func_id or .cv_inline_site_id");
 307     return false;
 308   }
 309
 310   // Track the section
 311   if (FI->Section == nullptr)
 312     FI->Section = getCurrentSectionOnly();
 313   else if (FI->Section != getCurrentSectionOnly()) {
 314     getContext().reportError(
 315         Loc,
 316         "all .cv_loc directives for a function must be in the same section");
 317     return false;
 318   }
 319   return true;
 320 }
 321
 322 void MCStreamer::EmitCVLinetableDirective(unsigned FunctionId,
 323                                           const MCSymbol *Begin,
 324                                           const MCSymbol *End) {}
 325
 326 void MCStreamer::EmitCVInlineLinetableDirective(unsigned PrimaryFunctionId,
 327                                                 unsigned SourceFileId,
 328                                                 unsigned SourceLineNum,
 329                                                 const MCSymbol *FnStartSym,
 330                                                 const MCSymbol *FnEndSym) {}
 331
 332 /// Only call this on endian-specific types like ulittle16_t and little32_t, or
 333 /// structs composed of them.
 334 template <typename T>
 335 static void copyBytesForDefRange(SmallString<20> &BytePrefix,
 336                                  codeview::SymbolKind SymKind,
 337                                  const T &DefRangeHeader) {
 338   BytePrefix.resize(2 + sizeof(T));
 339   codeview::ulittle16_t SymKindLE = codeview::ulittle16_t(SymKind);
 340   memcpy(&BytePrefix[0], &SymKindLE, 2);
 341   memcpy(&BytePrefix[2], &DefRangeHeader, sizeof(T));
 342 }
 343
 344 void MCStreamer::EmitCVDefRangeDirective(
 345     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
 346     StringRef FixedSizePortion) {}
 347
 348 void MCStreamer::EmitCVDefRangeDirective(
 349     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
 350     codeview::DefRangeRegisterRelSym::Header DRHdr) {
 351   SmallString<20> BytePrefix;
 352   copyBytesForDefRange(BytePrefix, codeview::S_DEFRANGE_REGISTER_REL, DRHdr);
 353   EmitCVDefRangeDirective(Ranges, BytePrefix);
 354 }
 355
 356 void MCStreamer::EmitCVDefRangeDirective(
 357     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
 358     codeview::DefRangeSubfieldRegisterSym::Header DRHdr) {
 359   SmallString<20> BytePrefix;
 360   copyBytesForDefRange(BytePrefix, codeview::S_DEFRANGE_SUBFIELD_REGISTER,
 361                        DRHdr);
 362   EmitCVDefRangeDirective(Ranges, BytePrefix);
 363 }
 364
 365 void MCStreamer::EmitCVDefRangeDirective(
 366     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
 367     codeview::DefRangeRegisterSym::Header DRHdr) {
 368   SmallString<20> BytePrefix;
 369   copyBytesForDefRange(BytePrefix, codeview::S_DEFRANGE_REGISTER, DRHdr);
 370   EmitCVDefRangeDirective(Ranges, BytePrefix);
 371 }
 372
 373 void MCStreamer::EmitCVDefRangeDirective(
 374     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
 375     codeview::DefRangeFramePointerRelSym::Header DRHdr) {
 376   SmallString<20> BytePrefix;
 377   copyBytesForDefRange(BytePrefix, codeview::S_DEFRANGE_FRAMEPOINTER_REL,
 378                        DRHdr);
 379   EmitCVDefRangeDirective(Ranges, BytePrefix);
 380 }
 381
 382 void MCStreamer::EmitEHSymAttributes(const MCSymbol *Symbol,
 383                                      MCSymbol *EHSymbol) {
 384 }
 385
 386 void MCStreamer::InitSections(bool NoExecStack) {
 387   SwitchSection(getContext().getObjectFileInfo()->getTextSection());
 388 }
 389
 390 void MCStreamer::AssignFragment(MCSymbol *Symbol, MCFragment *Fragment) {
 391   assert(Fragment);
 392   Symbol->setFragment(Fragment);
 393
 394   // As we emit symbols into a section, track the order so that they can
 395   // be sorted upon later. Zero is reserved to mean 'unemitted'.
 396   SymbolOrdering[Symbol] = 1 + SymbolOrdering.size();
 397 }
 398
 399 void MCStreamer::EmitLabel(MCSymbol *Symbol, SMLoc Loc) {
 400   Symbol->redefineIfPossible();
 401
 402   if (!Symbol->isUndefined() || Symbol->isVariable())
 403     return getContext().reportError(Loc, "invalid symbol redefinition");
 404
 405   assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
 406   assert(getCurrentSectionOnly() && "Cannot emit before setting section!");
 407   assert(!Symbol->getFragment() && "Unexpected fragment on symbol data!");
 408   assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
 409
 410   Symbol->setFragment(&getCurrentSectionOnly()->getDummyFragment());
 411
 412   MCTargetStreamer *TS = getTargetStreamer();
 413   if (TS)
 414     TS->emitLabel(Symbol);
 415 }
 416
 417 void MCStreamer::EmitCFISections(bool EH, bool Debug) {
 418   assert(EH || Debug);
 419 }
 420
 421 void MCStreamer::EmitCFIStartProc(bool IsSimple, SMLoc Loc) {
 422   if (hasUnfinishedDwarfFrameInfo())
 423     return getContext().reportError(
 424         Loc, "starting new .cfi frame before finishing the previous one");
 425
 426   MCDwarfFrameInfo Frame;
 427   Frame.IsSimple = IsSimple;
 428   EmitCFIStartProcImpl(Frame);
 429
 430   const MCAsmInfo* MAI = Context.getAsmInfo();
 431   if (MAI) {
 432     for (const MCCFIInstruction& Inst : MAI->getInitialFrameState()) {
 433       if (Inst.getOperation() == MCCFIInstruction::OpDefCfa ||
 434           Inst.getOperation() == MCCFIInstruction::OpDefCfaRegister) {
 435         Frame.CurrentCfaRegister = Inst.getRegister();
 436       }
 437     }
 438   }
 439
 440   DwarfFrameInfos.push_back(Frame);
 441 }
 442
 443 void MCStreamer::EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) {
 444 }
 445
 446 void MCStreamer::EmitCFIEndProc() {
 447   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 448   if (!CurFrame)
 449     return;
 450   EmitCFIEndProcImpl(*CurFrame);
 451 }
 452
 453 void MCStreamer::EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) {
 454   // Put a dummy non-null value in Frame.End to mark that this frame has been
 455   // closed.
 456   Frame.End = (MCSymbol *)1;
 457 }
 458
 459 MCSymbol *MCStreamer::EmitCFILabel() {
 460   // Return a dummy non-null value so that label fields appear filled in when
 461   // generating textual assembly.
 462   return (MCSymbol *)1;
 463 }
 464
 465 void MCStreamer::EmitCFIDefCfa(int64_t Register, int64_t Offset) {
 466   MCSymbol *Label = EmitCFILabel();
 467   MCCFIInstruction Instruction =
 468     MCCFIInstruction::createDefCfa(Label, Register, Offset);
 469   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 470   if (!CurFrame)
 471     return;
 472   CurFrame->Instructions.push_back(Instruction);
 473   CurFrame->CurrentCfaRegister = static_cast<unsigned>(Register);
 474 }
 475
 476 void MCStreamer::EmitCFIDefCfaOffset(int64_t Offset) {
 477   MCSymbol *Label = EmitCFILabel();
 478   MCCFIInstruction Instruction =
 479     MCCFIInstruction::createDefCfaOffset(Label, Offset);
 480   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 481   if (!CurFrame)
 482     return;
 483   CurFrame->Instructions.push_back(Instruction);
 484 }
 485
 486 void MCStreamer::EmitCFIAdjustCfaOffset(int64_t Adjustment) {
 487   MCSymbol *Label = EmitCFILabel();
 488   MCCFIInstruction Instruction =
 489     MCCFIInstruction::createAdjustCfaOffset(Label, Adjustment);
 490   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 491   if (!CurFrame)
 492     return;
 493   CurFrame->Instructions.push_back(Instruction);
 494 }
 495
 496 void MCStreamer::EmitCFIDefCfaRegister(int64_t Register) {
 497   MCSymbol *Label = EmitCFILabel();
 498   MCCFIInstruction Instruction =
 499     MCCFIInstruction::createDefCfaRegister(Label, Register);
 500   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 501   if (!CurFrame)
 502     return;
 503   CurFrame->Instructions.push_back(Instruction);
 504   CurFrame->CurrentCfaRegister = static_cast<unsigned>(Register);
 505 }
 506
 507 void MCStreamer::EmitCFIOffset(int64_t Register, int64_t Offset) {
 508   MCSymbol *Label = EmitCFILabel();
 509   MCCFIInstruction Instruction =
 510     MCCFIInstruction::createOffset(Label, Register, Offset);
 511   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 512   if (!CurFrame)
 513     return;
 514   CurFrame->Instructions.push_back(Instruction);
 515 }
 516
 517 void MCStreamer::EmitCFIRelOffset(int64_t Register, int64_t Offset) {
 518   MCSymbol *Label = EmitCFILabel();
 519   MCCFIInstruction Instruction =
 520     MCCFIInstruction::createRelOffset(Label, Register, Offset);
 521   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 522   if (!CurFrame)
 523     return;
 524   CurFrame->Instructions.push_back(Instruction);
 525 }
 526
 527 void MCStreamer::EmitCFIPersonality(const MCSymbol *Sym,
 528                                     unsigned Encoding) {
 529   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 530   if (!CurFrame)
 531     return;
 532   CurFrame->Personality = Sym;
 533   CurFrame->PersonalityEncoding = Encoding;
 534 }
 535
 536 void MCStreamer::EmitCFILsda(const MCSymbol *Sym, unsigned Encoding) {
 537   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 538   if (!CurFrame)
 539     return;
 540   CurFrame->Lsda = Sym;
 541   CurFrame->LsdaEncoding = Encoding;
 542 }
 543
 544 void MCStreamer::EmitCFIRememberState() {
 545   MCSymbol *Label = EmitCFILabel();
 546   MCCFIInstruction Instruction = MCCFIInstruction::createRememberState(Label);
 547   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 548   if (!CurFrame)
 549     return;
 550   CurFrame->Instructions.push_back(Instruction);
 551 }
 552
 553 void MCStreamer::EmitCFIRestoreState() {
 554   // FIXME: Error if there is no matching cfi_remember_state.
 555   MCSymbol *Label = EmitCFILabel();
 556   MCCFIInstruction Instruction = MCCFIInstruction::createRestoreState(Label);
 557   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 558   if (!CurFrame)
 559     return;
 560   CurFrame->Instructions.push_back(Instruction);
 561 }
 562
 563 void MCStreamer::EmitCFISameValue(int64_t Register) {
 564   MCSymbol *Label = EmitCFILabel();
 565   MCCFIInstruction Instruction =
 566     MCCFIInstruction::createSameValue(Label, Register);
 567   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 568   if (!CurFrame)
 569     return;
 570   CurFrame->Instructions.push_back(Instruction);
 571 }
 572
 573 void MCStreamer::EmitCFIRestore(int64_t Register) {
 574   MCSymbol *Label = EmitCFILabel();
 575   MCCFIInstruction Instruction =
 576     MCCFIInstruction::createRestore(Label, Register);
 577   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 578   if (!CurFrame)
 579     return;
 580   CurFrame->Instructions.push_back(Instruction);
 581 }
 582
 583 void MCStreamer::EmitCFIEscape(StringRef Values) {
 584   MCSymbol *Label = EmitCFILabel();
 585   MCCFIInstruction Instruction = MCCFIInstruction::createEscape(Label, Values);
 586   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 587   if (!CurFrame)
 588     return;
 589   CurFrame->Instructions.push_back(Instruction);
 590 }
 591
 592 void MCStreamer::EmitCFIGnuArgsSize(int64_t Size) {
 593   MCSymbol *Label = EmitCFILabel();
 594   MCCFIInstruction Instruction =
 595     MCCFIInstruction::createGnuArgsSize(Label, Size);
 596   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 597   if (!CurFrame)
 598     return;
 599   CurFrame->Instructions.push_back(Instruction);
 600 }
 601
 602 void MCStreamer::EmitCFISignalFrame() {
 603   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 604   if (!CurFrame)
 605     return;
 606   CurFrame->IsSignalFrame = true;
 607 }
 608
 609 void MCStreamer::EmitCFIUndefined(int64_t Register) {
 610   MCSymbol *Label = EmitCFILabel();
 611   MCCFIInstruction Instruction =
 612     MCCFIInstruction::createUndefined(Label, Register);
 613   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 614   if (!CurFrame)
 615     return;
 616   CurFrame->Instructions.push_back(Instruction);
 617 }
 618
 619 void MCStreamer::EmitCFIRegister(int64_t Register1, int64_t Register2) {
 620   MCSymbol *Label = EmitCFILabel();
 621   MCCFIInstruction Instruction =
 622     MCCFIInstruction::createRegister(Label, Register1, Register2);
 623   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 624   if (!CurFrame)
 625     return;
 626   CurFrame->Instructions.push_back(Instruction);
 627 }
 628
 629 void MCStreamer::EmitCFIWindowSave() {
 630   MCSymbol *Label = EmitCFILabel();
 631   MCCFIInstruction Instruction =
 632     MCCFIInstruction::createWindowSave(Label);
 633   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 634   if (!CurFrame)
 635     return;
 636   CurFrame->Instructions.push_back(Instruction);
 637 }
 638
 639 void MCStreamer::EmitCFINegateRAState() {
 640   MCSymbol *Label = EmitCFILabel();
 641   MCCFIInstruction Instruction = MCCFIInstruction::createNegateRAState(Label);
 642   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 643   if (!CurFrame)
 644     return;
 645   CurFrame->Instructions.push_back(Instruction);
 646 }
 647
 648 void MCStreamer::EmitCFIReturnColumn(int64_t Register) {
 649   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
 650   if (!CurFrame)
 651     return;
 652   CurFrame->RAReg = Register;
 653 }
 654
 655 WinEH::FrameInfo *MCStreamer::EnsureValidWinFrameInfo(SMLoc Loc) {
 656   const MCAsmInfo *MAI = Context.getAsmInfo();
 657   if (!MAI->usesWindowsCFI()) {
 658     getContext().reportError(
 659         Loc, ".seh_* directives are not supported on this target");
 660     return nullptr;
 661   }
 662   if (!CurrentWinFrameInfo || CurrentWinFrameInfo->End) {
 663     getContext().reportError(
 664         Loc, ".seh_ directive must appear within an active frame");
 665     return nullptr;
 666   }
 667   return CurrentWinFrameInfo;
 668 }
 669
 670 void MCStreamer::EmitWinCFIStartProc(const MCSymbol *Symbol, SMLoc Loc) {
 671   const MCAsmInfo *MAI = Context.getAsmInfo();
 672   if (!MAI->usesWindowsCFI())
 673     return getContext().reportError(
 674         Loc, ".seh_* directives are not supported on this target");
 675   if (CurrentWinFrameInfo && !CurrentWinFrameInfo->End)
 676     getContext().reportError(
 677         Loc, "Starting a function before ending the previous one!");
 678
 679   MCSymbol *StartProc = EmitCFILabel();
 680
 681   WinFrameInfos.emplace_back(
 682       std::make_unique<WinEH::FrameInfo>(Symbol, StartProc));
 683   CurrentWinFrameInfo = WinFrameInfos.back().get();
 684   CurrentWinFrameInfo->TextSection = getCurrentSectionOnly();
 685 }
 686
 687 void MCStreamer::EmitWinCFIEndProc(SMLoc Loc) {
 688   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
 689   if (!CurFrame)
 690     return;
 691   if (CurFrame->ChainedParent)
 692     getContext().reportError(Loc, "Not all chained regions terminated!");
 693
 694   MCSymbol *Label = EmitCFILabel();
 695   CurFrame->End = Label;
 696 }
 697
 698 void MCStreamer::EmitWinCFIFuncletOrFuncEnd(SMLoc Loc) {
 699   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
 700   if (!CurFrame)
 701     return;
 702   if (CurFrame->ChainedParent)
 703     getContext().reportError(Loc, "Not all chained regions terminated!");
 704
 705   MCSymbol *Label = EmitCFILabel();
 706   CurFrame->FuncletOrFuncEnd = Label;
 707 }
 708
 709 void MCStreamer::EmitWinCFIStartChained(SMLoc Loc) {
 710   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
 711   if (!CurFrame)
 712     return;
 713
 714   MCSymbol *StartProc = EmitCFILabel();
 715
 716   WinFrameInfos.emplace_back(std::make_unique<WinEH::FrameInfo>(
 717       CurFrame->Function, StartProc, CurFrame));
 718   CurrentWinFrameInfo = WinFrameInfos.back().get();
 719   CurrentWinFrameInfo->TextSection = getCurrentSectionOnly();
 720 }
 721
 722 void MCStreamer::EmitWinCFIEndChained(SMLoc Loc) {
 723   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
 724   if (!CurFrame)
 725     return;
 726   if (!CurFrame->ChainedParent)
 727     return getContext().reportError(
 728         Loc, "End of a chained region outside a chained region!");
 729
 730   MCSymbol *Label = EmitCFILabel();
 731
 732   CurFrame->End = Label;
 733   CurrentWinFrameInfo = const_cast<WinEH::FrameInfo *>(CurFrame->ChainedParent);
 734 }
 735
 736 void MCStreamer::EmitWinEHHandler(const MCSymbol *Sym, bool Unwind, bool Except,
 737                                   SMLoc Loc) {
 738   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
 739   if (!CurFrame)
 740     return;
 741   if (CurFrame->ChainedParent)
 742     return getContext().reportError(
 743         Loc, "Chained unwind areas can't have handlers!");
 744   CurFrame->ExceptionHandler = Sym;
 745   if (!Except && !Unwind)
 746     getContext().reportError(Loc, "Don't know what kind of handler this is!");
 747   if (Unwind)
 748     CurFrame->HandlesUnwind = true;
 749   if (Except)
 750     CurFrame->HandlesExceptions = true;
 751 }
 752
 753 void MCStreamer::EmitWinEHHandlerData(SMLoc Loc) {
 754   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
 755   if (!CurFrame)
 756     return;
 757   if (CurFrame->ChainedParent)
 758     getContext().reportError(Loc, "Chained unwind areas can't have handlers!");
 759 }
 760
 761 void MCStreamer::emitCGProfileEntry(const MCSymbolRefExpr *From,
 762                                     const MCSymbolRefExpr *To, uint64_t Count) {
 763 }
 764
 765 static MCSection *getWinCFISection(MCContext &Context, unsigned *NextWinCFIID,
 766                                    MCSection *MainCFISec,
 767                                    const MCSection *TextSec) {
 768   // If this is the main .text section, use the main unwind info section.
 769   if (TextSec == Context.getObjectFileInfo()->getTextSection())
 770     return MainCFISec;
 771
 772   const auto *TextSecCOFF = cast<MCSectionCOFF>(TextSec);
 773   auto *MainCFISecCOFF = cast<MCSectionCOFF>(MainCFISec);
 774   unsigned UniqueID = TextSecCOFF->getOrAssignWinCFISectionID(NextWinCFIID);
 775
 776   // If this section is COMDAT, this unwind section should be COMDAT associative
 777   // with its group.
 778   const MCSymbol *KeySym = nullptr;
 779   if (TextSecCOFF->getCharacteristics() & COFF::IMAGE_SCN_LNK_COMDAT) {
 780     KeySym = TextSecCOFF->getCOMDATSymbol();
 781
 782     // In a GNU environment, we can't use associative comdats. Instead, do what
 783     // GCC does, which is to make plain comdat selectany section named like
 784     // ".[px]data$_Z3foov".
 785     if (!Context.getAsmInfo()->hasCOFFAssociativeComdats()) {
 786       std::string SectionName =
 787           (MainCFISecCOFF->getSectionName() + "$" +
 788            TextSecCOFF->getSectionName().split('$').second)
 789               .str();
 790       return Context.getCOFFSection(
 791           SectionName,
 792           MainCFISecCOFF->getCharacteristics() | COFF::IMAGE_SCN_LNK_COMDAT,
 793           MainCFISecCOFF->getKind(), "", COFF::IMAGE_COMDAT_SELECT_ANY);
 794     }
 795   }
 796
 797   return Context.getAssociativeCOFFSection(MainCFISecCOFF, KeySym, UniqueID);
 798 }
 799
 800 MCSection *MCStreamer::getAssociatedPDataSection(const MCSection *TextSec) {
 801   return getWinCFISection(getContext(), &NextWinCFIID,
 802                           getContext().getObjectFileInfo()->getPDataSection(),
 803                           TextSec);
 804 }
 805
 806 MCSection *MCStreamer::getAssociatedXDataSection(const MCSection *TextSec) {
 807   return getWinCFISection(getContext(), &NextWinCFIID,
 808                           getContext().getObjectFileInfo()->getXDataSection(),
 809                           TextSec);
 810 }
 811
 812 void MCStreamer::EmitSyntaxDirective() {}
 813
 814 static unsigned encodeSEHRegNum(MCContext &Ctx, MCRegister Reg) {
 815   return Ctx.getRegisterInfo()->getSEHRegNum(Reg);
 816 }
 817
 818 void MCStreamer::EmitWinCFIPushReg(MCRegister Register, SMLoc Loc) {
 819   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
 820   if (!CurFrame)
 821     return;
 822
 823   MCSymbol *Label = EmitCFILabel();
 824
 825   WinEH::Instruction Inst = Win64EH::Instruction::PushNonVol(
 826       Label, encodeSEHRegNum(Context, Register));
 827   CurFrame->Instructions.push_back(Inst);
 828 }
 829
 830 void MCStreamer::EmitWinCFISetFrame(MCRegister Register, unsigned Offset,
 831                                     SMLoc Loc) {
 832   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
 833   if (!CurFrame)
 834     return;
 835   if (CurFrame->LastFrameInst >= 0)
 836     return getContext().reportError(
 837         Loc, "frame register and offset can be set at most once");
 838   if (Offset & 0x0F)
 839     return getContext().reportError(Loc, "offset is not a multiple of 16");
 840   if (Offset > 240)
 841     return getContext().reportError(
 842         Loc, "frame offset must be less than or equal to 240");
 843
 844   MCSymbol *Label = EmitCFILabel();
 845
 846   WinEH::Instruction Inst = Win64EH::Instruction::SetFPReg(
 847       Label, encodeSEHRegNum(getContext(), Register), Offset);
 848   CurFrame->LastFrameInst = CurFrame->Instructions.size();
 849   CurFrame->Instructions.push_back(Inst);
 850 }
 851
 852 void MCStreamer::EmitWinCFIAllocStack(unsigned Size, SMLoc Loc) {
 853   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
 854   if (!CurFrame)
 855     return;
 856   if (Size == 0)
 857     return getContext().reportError(Loc,
 858                                     "stack allocation size must be non-zero");
 859   if (Size & 7)
 860     return getContext().reportError(
 861         Loc, "stack allocation size is not a multiple of 8");
 862
 863   MCSymbol *Label = EmitCFILabel();
 864
 865   WinEH::Instruction Inst = Win64EH::Instruction::Alloc(Label, Size);
 866   CurFrame->Instructions.push_back(Inst);
 867 }
 868
 869 void MCStreamer::EmitWinCFISaveReg(MCRegister Register, unsigned Offset,
 870                                    SMLoc Loc) {
 871   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
 872   if (!CurFrame)
 873     return;
 874
 875   if (Offset & 7)
 876     return getContext().reportError(
 877         Loc, "register save offset is not 8 byte aligned");
 878
 879   MCSymbol *Label = EmitCFILabel();
 880
 881   WinEH::Instruction Inst = Win64EH::Instruction::SaveNonVol(
 882       Label, encodeSEHRegNum(Context, Register), Offset);
 883   CurFrame->Instructions.push_back(Inst);
 884 }
 885
 886 void MCStreamer::EmitWinCFISaveXMM(MCRegister Register, unsigned Offset,
 887                                    SMLoc Loc) {
 888   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
 889   if (!CurFrame)
 890     return;
 891   if (Offset & 0x0F)
 892     return getContext().reportError(Loc, "offset is not a multiple of 16");
 893
 894   MCSymbol *Label = EmitCFILabel();
 895
 896   WinEH::Instruction Inst = Win64EH::Instruction::SaveXMM(
 897       Label, encodeSEHRegNum(Context, Register), Offset);
 898   CurFrame->Instructions.push_back(Inst);
 899 }
 900
 901 void MCStreamer::EmitWinCFIPushFrame(bool Code, SMLoc Loc) {
 902   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
 903   if (!CurFrame)
 904     return;
 905   if (!CurFrame->Instructions.empty())
 906     return getContext().reportError(
 907         Loc, "If present, PushMachFrame must be the first UOP");
 908
 909   MCSymbol *Label = EmitCFILabel();
 910
 911   WinEH::Instruction Inst = Win64EH::Instruction::PushMachFrame(Label, Code);
 912   CurFrame->Instructions.push_back(Inst);
 913 }
 914
 915 void MCStreamer::EmitWinCFIEndProlog(SMLoc Loc) {
 916   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
 917   if (!CurFrame)
 918     return;
 919
 920   MCSymbol *Label = EmitCFILabel();
 921
 922   CurFrame->PrologEnd = Label;
 923 }
 924
 925 void MCStreamer::EmitCOFFSafeSEH(MCSymbol const *Symbol) {}
 926
 927 void MCStreamer::EmitCOFFSymbolIndex(MCSymbol const *Symbol) {}
 928
 929 void MCStreamer::EmitCOFFSectionIndex(MCSymbol const *Symbol) {}
 930
 931 void MCStreamer::EmitCOFFSecRel32(MCSymbol const *Symbol, uint64_t Offset) {}
 932
 933 void MCStreamer::EmitCOFFImgRel32(MCSymbol const *Symbol, int64_t Offset) {}
 934
 935 /// EmitRawText - If this file is backed by an assembly streamer, this dumps
 936 /// the specified string in the output .s file.  This capability is
 937 /// indicated by the hasRawTextSupport() predicate.
 938 void MCStreamer::EmitRawTextImpl(StringRef String) {
 939   // This is not llvm_unreachable for the sake of out of tree backend
 940   // developers who may not have assembly streamers and should serve as a
 941   // reminder to not accidentally call EmitRawText in the absence of such.
 942   report_fatal_error("EmitRawText called on an MCStreamer that doesn't support "
 943                      "it (target backend is likely missing an AsmStreamer "
 944                      "implementation)");
 945 }
 946
 947 void MCStreamer::EmitRawText(const Twine &T) {
 948   SmallString<128> Str;
 949   EmitRawTextImpl(T.toStringRef(Str));
 950 }
 951
 952 void MCStreamer::EmitWindowsUnwindTables() {
 953 }
 954
 955 void MCStreamer::Finish() {
 956   if ((!DwarfFrameInfos.empty() && !DwarfFrameInfos.back().End) ||
 957       (!WinFrameInfos.empty() && !WinFrameInfos.back()->End)) {
 958     getContext().reportError(SMLoc(), "Unfinished frame!");
 959     return;
 960   }
 961
 962   MCTargetStreamer *TS = getTargetStreamer();
 963   if (TS)
 964     TS->finish();
 965
 966   FinishImpl();
 967 }
 968
 969 void MCStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
 970   visitUsedExpr(*Value);
 971   Symbol->setVariableValue(Value);
 972
 973   MCTargetStreamer *TS = getTargetStreamer();
 974   if (TS)
 975     TS->emitAssignment(Symbol, Value);
 976 }
 977
 978 void MCTargetStreamer::prettyPrintAsm(MCInstPrinter &InstPrinter,
 979                                       raw_ostream &OS, const MCInst &Inst,
 980                                       const MCSubtargetInfo &STI) {
 981   InstPrinter.printInst(&Inst, OS, "", STI);
 982 }
 983
 984 void MCStreamer::visitUsedSymbol(const MCSymbol &Sym) {
 985 }
 986
 987 void MCStreamer::visitUsedExpr(const MCExpr &Expr) {
 988   switch (Expr.getKind()) {
 989   case MCExpr::Target:
 990     cast<MCTargetExpr>(Expr).visitUsedExpr(*this);
 991     break;
 992
 993   case MCExpr::Constant:
 994     break;
 995
 996   case MCExpr::Binary: {
 997     const MCBinaryExpr &BE = cast<MCBinaryExpr>(Expr);
 998     visitUsedExpr(*BE.getLHS());
 999     visitUsedExpr(*BE.getRHS());
1000     break;
1001   }
1002
1003   case MCExpr::SymbolRef:
1004     visitUsedSymbol(cast<MCSymbolRefExpr>(Expr).getSymbol());
1005     break;
1006
1007   case MCExpr::Unary:
1008     visitUsedExpr(*cast<MCUnaryExpr>(Expr).getSubExpr());
1009     break;
1010   }
1011 }
1012
1013 void MCStreamer::EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &) {
1014   // Scan for values.
1015   for (unsigned i = Inst.getNumOperands(); i--;)
1016     if (Inst.getOperand(i).isExpr())
1017       visitUsedExpr(*Inst.getOperand(i).getExpr());
1018 }
1019
1020 void MCStreamer::emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo,
1021                                         unsigned Size) {
1022   // Get the Hi-Lo expression.
1023   const MCExpr *Diff =
1024       MCBinaryExpr::createSub(MCSymbolRefExpr::create(Hi, Context),
1025                               MCSymbolRefExpr::create(Lo, Context), Context);
1026
1027   const MCAsmInfo *MAI = Context.getAsmInfo();
1028   if (!MAI->doesSetDirectiveSuppressReloc()) {
1029     EmitValue(Diff, Size);
1030     return;
1031   }
1032
1033   // Otherwise, emit with .set (aka assignment).
1034   MCSymbol *SetLabel = Context.createTempSymbol("set", true);
1035   EmitAssignment(SetLabel, Diff);
1036   EmitSymbolValue(SetLabel, Size);
1037 }
1038
1039 void MCStreamer::emitAbsoluteSymbolDiffAsULEB128(const MCSymbol *Hi,
1040                                                  const MCSymbol *Lo) {
1041   // Get the Hi-Lo expression.
1042   const MCExpr *Diff =
1043       MCBinaryExpr::createSub(MCSymbolRefExpr::create(Hi, Context),
1044                               MCSymbolRefExpr::create(Lo, Context), Context);
1045
1046   EmitULEB128Value(Diff);
1047 }
1048
1049 void MCStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {}
1050 void MCStreamer::EmitThumbFunc(MCSymbol *Func) {}
1051 void MCStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {}
1052 void MCStreamer::BeginCOFFSymbolDef(const MCSymbol *Symbol) {
1053   llvm_unreachable("this directive only supported on COFF targets");
1054 }
1055 void MCStreamer::EndCOFFSymbolDef() {
1056   llvm_unreachable("this directive only supported on COFF targets");
1057 }
1058 void MCStreamer::EmitFileDirective(StringRef Filename) {}
1059 void MCStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
1060   llvm_unreachable("this directive only supported on COFF targets");
1061 }
1062 void MCStreamer::EmitCOFFSymbolType(int Type) {
1063   llvm_unreachable("this directive only supported on COFF targets");
1064 }
1065 void MCStreamer::EmitXCOFFLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
1066                                             unsigned ByteAlign) {
1067   llvm_unreachable("this directive only supported on XCOFF targets");
1068 }
1069 void MCStreamer::emitELFSize(MCSymbol *Symbol, const MCExpr *Value) {}
1070 void MCStreamer::emitELFSymverDirective(StringRef AliasName,
1071                                         const MCSymbol *Aliasee) {}
1072 void MCStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
1073                                        unsigned ByteAlignment) {}
1074 void MCStreamer::EmitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
1075                                 uint64_t Size, unsigned ByteAlignment) {}
1076 void MCStreamer::ChangeSection(MCSection *, const MCExpr *) {}
1077 void MCStreamer::EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {}
1078 void MCStreamer::EmitBytes(StringRef Data) {}
1079 void MCStreamer::EmitBinaryData(StringRef Data) { EmitBytes(Data); }
1080 void MCStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size, SMLoc Loc) {
1081   visitUsedExpr(*Value);
1082 }
1083 void MCStreamer::EmitULEB128Value(const MCExpr *Value) {}
1084 void MCStreamer::EmitSLEB128Value(const MCExpr *Value) {}
1085 void MCStreamer::emitFill(const MCExpr &NumBytes, uint64_t Value, SMLoc Loc) {}
1086 void MCStreamer::emitFill(const MCExpr &NumValues, int64_t Size, int64_t Expr,
1087                           SMLoc Loc) {}
1088 void MCStreamer::EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
1089                                       unsigned ValueSize,
1090                                       unsigned MaxBytesToEmit) {}
1091 void MCStreamer::EmitCodeAlignment(unsigned ByteAlignment,
1092                                    unsigned MaxBytesToEmit) {}
1093 void MCStreamer::emitValueToOffset(const MCExpr *Offset, unsigned char Value,
1094                                    SMLoc Loc) {}
1095 void MCStreamer::EmitBundleAlignMode(unsigned AlignPow2) {}
1096 void MCStreamer::EmitBundleLock(bool AlignToEnd) {}
1097 void MCStreamer::FinishImpl() {}
1098 void MCStreamer::EmitBundleUnlock() {}
1099
1100 void MCStreamer::SwitchSection(MCSection *Section, const MCExpr *Subsection) {
1101   assert(Section && "Cannot switch to a null section!");
1102   MCSectionSubPair curSection = SectionStack.back().first;
1103   SectionStack.back().second = curSection;
1104   if (MCSectionSubPair(Section, Subsection) != curSection) {
1105     ChangeSection(Section, Subsection);
1106     SectionStack.back().first = MCSectionSubPair(Section, Subsection);
1107     assert(!Section->hasEnded() && "Section already ended");
1108     MCSymbol *Sym = Section->getBeginSymbol();
1109     if (Sym && !Sym->isInSection())
1110       EmitLabel(Sym);
1111   }
1112 }
1113
1114 MCSymbol *MCStreamer::endSection(MCSection *Section) {
1115   // TODO: keep track of the last subsection so that this symbol appears in the
1116   // correct place.
1117   MCSymbol *Sym = Section->getEndSymbol(Context);
1118   if (Sym->isInSection())
1119     return Sym;
1120
1121   SwitchSection(Section);
1122   EmitLabel(Sym);
1123   return Sym;
1124 }
1125
1126 void MCStreamer::EmitVersionForTarget(const Triple &Target,
1127                                       const VersionTuple &SDKVersion) {
1128   if (!Target.isOSBinFormatMachO() || !Target.isOSDarwin())
1129     return;
1130   // Do we even know the version?
1131   if (Target.getOSMajorVersion() == 0)
1132     return;
1133
1134   unsigned Major;
1135   unsigned Minor;
1136   unsigned Update;
1137   if (Target.isMacCatalystEnvironment()) {
1138     // Mac Catalyst always uses the build version load command.
1139     Target.getiOSVersion(Major, Minor, Update);
1140     assert(Major && "A non-zero major version is expected");
1141     EmitBuildVersion(MachO::PLATFORM_MACCATALYST, Major, Minor, Update,
1142                      SDKVersion);
1143     return;
1144   }
1145
1146   MCVersionMinType VersionType;
1147   if (Target.isWatchOS()) {
1148     VersionType = MCVM_WatchOSVersionMin;
1149     Target.getWatchOSVersion(Major, Minor, Update);
1150   } else if (Target.isTvOS()) {
1151     VersionType = MCVM_TvOSVersionMin;
1152     Target.getiOSVersion(Major, Minor, Update);
1153   } else if (Target.isMacOSX()) {
1154     VersionType = MCVM_OSXVersionMin;
1155     if (!Target.getMacOSXVersion(Major, Minor, Update))
1156       Major = 0;
1157   } else {
1158     VersionType = MCVM_IOSVersionMin;
1159     Target.getiOSVersion(Major, Minor, Update);
1160   }
1161   if (Major != 0)
1162     EmitVersionMin(VersionType, Major, Minor, Update, SDKVersion);
1163 }