lib/MC/MCContext.cpp

   1 //===- lib/MC/MCContext.cpp - Machine Code Context ------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #include "llvm/MC/MCContext.h"
  11 #include "llvm/ADT/SmallString.h"
  12 #include "llvm/ADT/SmallVector.h"
  13 #include "llvm/ADT/StringMap.h"
  14 #include "llvm/ADT/StringRef.h"
  15 #include "llvm/ADT/Twine.h"
  16 #include "llvm/BinaryFormat/COFF.h"
  17 #include "llvm/BinaryFormat/ELF.h"
  18 #include "llvm/MC/MCAsmInfo.h"
  19 #include "llvm/MC/MCCodeView.h"
  20 #include "llvm/MC/MCDwarf.h"
  21 #include "llvm/MC/MCExpr.h"
  22 #include "llvm/MC/MCFragment.h"
  23 #include "llvm/MC/MCLabel.h"
  24 #include "llvm/MC/MCObjectFileInfo.h"
  25 #include "llvm/MC/MCSectionCOFF.h"
  26 #include "llvm/MC/MCSectionELF.h"
  27 #include "llvm/MC/MCSectionMachO.h"
  28 #include "llvm/MC/MCSectionWasm.h"
  29 #include "llvm/MC/MCStreamer.h"
  30 #include "llvm/MC/MCSymbol.h"
  31 #include "llvm/MC/MCSymbolCOFF.h"
  32 #include "llvm/MC/MCSymbolELF.h"
  33 #include "llvm/MC/MCSymbolMachO.h"
  34 #include "llvm/MC/MCSymbolWasm.h"
  35 #include "llvm/MC/SectionKind.h"
  36 #include "llvm/Support/Casting.h"
  37 #include "llvm/Support/CommandLine.h"
  38 #include "llvm/Support/ErrorHandling.h"
  39 #include "llvm/Support/MemoryBuffer.h"
  40 #include "llvm/Support/Signals.h"
  41 #include "llvm/Support/SourceMgr.h"
  42 #include "llvm/Support/raw_ostream.h"
  43 #include <cassert>
  44 #include <cstdlib>
  45 #include <tuple>
  46 #include <utility>
  47
  48 using namespace llvm;
  49
  50 static cl::opt<char*>
  51 AsSecureLogFileName("as-secure-log-file-name",
  52         cl::desc("As secure log file name (initialized from "
  53                  "AS_SECURE_LOG_FILE env variable)"),
  54         cl::init(getenv("AS_SECURE_LOG_FILE")), cl::Hidden);
  55
  56 MCContext::MCContext(const MCAsmInfo *mai, const MCRegisterInfo *mri,
  57                      const MCObjectFileInfo *mofi, const SourceMgr *mgr,
  58                      bool DoAutoReset)
  59     : SrcMgr(mgr), InlineSrcMgr(nullptr), MAI(mai), MRI(mri), MOFI(mofi),
  60       Symbols(Allocator), UsedNames(Allocator),
  61       CurrentDwarfLoc(0, 0, 0, DWARF2_FLAG_IS_STMT, 0, 0),
  62       AutoReset(DoAutoReset) {
  63   SecureLogFile = AsSecureLogFileName;
  64
  65   if (SrcMgr && SrcMgr->getNumBuffers())
  66     MainFileName =
  67         SrcMgr->getMemoryBuffer(SrcMgr->getMainFileID())->getBufferIdentifier();
  68 }
  69
  70 MCContext::~MCContext() {
  71   if (AutoReset)
  72     reset();
  73
  74   // NOTE: The symbols are all allocated out of a bump pointer allocator,
  75   // we don't need to free them here.
  76 }
  77
  78 //===----------------------------------------------------------------------===//
  79 // Module Lifetime Management
  80 //===----------------------------------------------------------------------===//
  81
  82 void MCContext::reset() {
  83   // Call the destructors so the fragments are freed
  84   COFFAllocator.DestroyAll();
  85   ELFAllocator.DestroyAll();
  86   MachOAllocator.DestroyAll();
  87
  88   MCSubtargetAllocator.DestroyAll();
  89   UsedNames.clear();
  90   Symbols.clear();
  91   Allocator.Reset();
  92   Instances.clear();
  93   CompilationDir.clear();
  94   MainFileName.clear();
  95   MCDwarfLineTablesCUMap.clear();
  96   SectionsForRanges.clear();
  97   MCGenDwarfLabelEntries.clear();
  98   DwarfDebugFlags = StringRef();
  99   DwarfCompileUnitID = 0;
 100   CurrentDwarfLoc = MCDwarfLoc(0, 0, 0, DWARF2_FLAG_IS_STMT, 0, 0);
 101
 102   CVContext.reset();
 103
 104   MachOUniquingMap.clear();
 105   ELFUniquingMap.clear();
 106   COFFUniquingMap.clear();
 107
 108   NextID.clear();
 109   AllowTemporaryLabels = true;
 110   DwarfLocSeen = false;
 111   GenDwarfForAssembly = false;
 112   GenDwarfFileNumber = 0;
 113
 114   HadError = false;
 115 }
 116
 117 //===----------------------------------------------------------------------===//
 118 // Symbol Manipulation
 119 //===----------------------------------------------------------------------===//
 120
 121 MCSymbol *MCContext::getOrCreateSymbol(const Twine &Name) {
 122   SmallString<128> NameSV;
 123   StringRef NameRef = Name.toStringRef(NameSV);
 124
 125   assert(!NameRef.empty() && "Normal symbols cannot be unnamed!");
 126
 127   MCSymbol *&Sym = Symbols[NameRef];
 128   if (!Sym)
 129     Sym = createSymbol(NameRef, false, false);
 130
 131   return Sym;
 132 }
 133
 134 MCSymbol *MCContext::getOrCreateFrameAllocSymbol(StringRef FuncName,
 135                                                  unsigned Idx) {
 136   return getOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) + FuncName +
 137                            "$frame_escape_" + Twine(Idx));
 138 }
 139
 140 MCSymbol *MCContext::getOrCreateParentFrameOffsetSymbol(StringRef FuncName) {
 141   return getOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) + FuncName +
 142                            "$parent_frame_offset");
 143 }
 144
 145 MCSymbol *MCContext::getOrCreateLSDASymbol(StringRef FuncName) {
 146   return getOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) + "__ehtable$" +
 147                            FuncName);
 148 }
 149
 150 MCSymbol *MCContext::createSymbolImpl(const StringMapEntry<bool> *Name,
 151                                       bool IsTemporary) {
 152   if (MOFI) {
 153     switch (MOFI->getObjectFileType()) {
 154     case MCObjectFileInfo::IsCOFF:
 155       return new (Name, *this) MCSymbolCOFF(Name, IsTemporary);
 156     case MCObjectFileInfo::IsELF:
 157       return new (Name, *this) MCSymbolELF(Name, IsTemporary);
 158     case MCObjectFileInfo::IsMachO:
 159       return new (Name, *this) MCSymbolMachO(Name, IsTemporary);
 160     case MCObjectFileInfo::IsWasm:
 161       return new (Name, *this) MCSymbolWasm(Name, IsTemporary);
 162     }
 163   }
 164   return new (Name, *this) MCSymbol(MCSymbol::SymbolKindUnset, Name,
 165                                     IsTemporary);
 166 }
 167
 168 MCSymbol *MCContext::createSymbol(StringRef Name, bool AlwaysAddSuffix,
 169                                   bool CanBeUnnamed) {
 170   if (CanBeUnnamed && !UseNamesOnTempLabels)
 171     return createSymbolImpl(nullptr, true);
 172
 173   // Determine whether this is a user written assembler temporary or normal
 174   // label, if used.
 175   bool IsTemporary = CanBeUnnamed;
 176   if (AllowTemporaryLabels && !IsTemporary)
 177     IsTemporary = Name.startswith(MAI->getPrivateGlobalPrefix());
 178
 179   SmallString<128> NewName = Name;
 180   bool AddSuffix = AlwaysAddSuffix;
 181   unsigned &NextUniqueID = NextID[Name];
 182   while (true) {
 183     if (AddSuffix) {
 184       NewName.resize(Name.size());
 185       raw_svector_ostream(NewName) << NextUniqueID++;
 186     }
 187     auto NameEntry = UsedNames.insert(std::make_pair(NewName, true));
 188     if (NameEntry.second || !NameEntry.first->second) {
 189       // Ok, we found a name.
 190       // Mark it as used for a non-section symbol.
 191       NameEntry.first->second = true;
 192       // Have the MCSymbol object itself refer to the copy of the string that is
 193       // embedded in the UsedNames entry.
 194       return createSymbolImpl(&*NameEntry.first, IsTemporary);
 195     }
 196     assert(IsTemporary && "Cannot rename non-temporary symbols");
 197     AddSuffix = true;
 198   }
 199   llvm_unreachable("Infinite loop");
 200 }
 201
 202 MCSymbol *MCContext::createTempSymbol(const Twine &Name, bool AlwaysAddSuffix,
 203                                       bool CanBeUnnamed) {
 204   SmallString<128> NameSV;
 205   raw_svector_ostream(NameSV) << MAI->getPrivateGlobalPrefix() << Name;
 206   return createSymbol(NameSV, AlwaysAddSuffix, CanBeUnnamed);
 207 }
 208
 209 MCSymbol *MCContext::createLinkerPrivateTempSymbol() {
 210   SmallString<128> NameSV;
 211   raw_svector_ostream(NameSV) << MAI->getLinkerPrivateGlobalPrefix() << "tmp";
 212   return createSymbol(NameSV, true, false);
 213 }
 214
 215 MCSymbol *MCContext::createTempSymbol(bool CanBeUnnamed) {
 216   return createTempSymbol("tmp", true, CanBeUnnamed);
 217 }
 218
 219 unsigned MCContext::NextInstance(unsigned LocalLabelVal) {
 220   MCLabel *&Label = Instances[LocalLabelVal];
 221   if (!Label)
 222     Label = new (*this) MCLabel(0);
 223   return Label->incInstance();
 224 }
 225
 226 unsigned MCContext::GetInstance(unsigned LocalLabelVal) {
 227   MCLabel *&Label = Instances[LocalLabelVal];
 228   if (!Label)
 229     Label = new (*this) MCLabel(0);
 230   return Label->getInstance();
 231 }
 232
 233 MCSymbol *MCContext::getOrCreateDirectionalLocalSymbol(unsigned LocalLabelVal,
 234                                                        unsigned Instance) {
 235   MCSymbol *&Sym = LocalSymbols[std::make_pair(LocalLabelVal, Instance)];
 236   if (!Sym)
 237     Sym = createTempSymbol(false);
 238   return Sym;
 239 }
 240
 241 MCSymbol *MCContext::createDirectionalLocalSymbol(unsigned LocalLabelVal) {
 242   unsigned Instance = NextInstance(LocalLabelVal);
 243   return getOrCreateDirectionalLocalSymbol(LocalLabelVal, Instance);
 244 }
 245
 246 MCSymbol *MCContext::getDirectionalLocalSymbol(unsigned LocalLabelVal,
 247                                                bool Before) {
 248   unsigned Instance = GetInstance(LocalLabelVal);
 249   if (!Before)
 250     ++Instance;
 251   return getOrCreateDirectionalLocalSymbol(LocalLabelVal, Instance);
 252 }
 253
 254 MCSymbol *MCContext::lookupSymbol(const Twine &Name) const {
 255   SmallString<128> NameSV;
 256   StringRef NameRef = Name.toStringRef(NameSV);
 257   return Symbols.lookup(NameRef);
 258 }
 259
 260 void MCContext::setSymbolValue(MCStreamer &Streamer,
 261                               StringRef Sym,
 262                               uint64_t Val) {
 263   auto Symbol = getOrCreateSymbol(Sym);
 264   Streamer.EmitAssignment(Symbol, MCConstantExpr::create(Val, *this));
 265 }
 266
 267 //===----------------------------------------------------------------------===//
 268 // Section Management
 269 //===----------------------------------------------------------------------===//
 270
 271 MCSectionMachO *MCContext::getMachOSection(StringRef Segment, StringRef Section,
 272                                            unsigned TypeAndAttributes,
 273                                            unsigned Reserved2, SectionKind Kind,
 274                                            const char *BeginSymName) {
 275   // We unique sections by their segment/section pair.  The returned section
 276   // may not have the same flags as the requested section, if so this should be
 277   // diagnosed by the client as an error.
 278
 279   // Form the name to look up.
 280   SmallString<64> Name;
 281   Name += Segment;
 282   Name.push_back(',');
 283   Name += Section;
 284
 285   // Do the lookup, if we have a hit, return it.
 286   MCSectionMachO *&Entry = MachOUniquingMap[Name];
 287   if (Entry)
 288     return Entry;
 289
 290   MCSymbol *Begin = nullptr;
 291   if (BeginSymName)
 292     Begin = createTempSymbol(BeginSymName, false);
 293
 294   // Otherwise, return a new section.
 295   return Entry = new (MachOAllocator.Allocate()) MCSectionMachO(
 296              Segment, Section, TypeAndAttributes, Reserved2, Kind, Begin);
 297 }
 298
 299 void MCContext::renameELFSection(MCSectionELF *Section, StringRef Name) {
 300   StringRef GroupName;
 301   if (const MCSymbol *Group = Section->getGroup())
 302     GroupName = Group->getName();
 303
 304   unsigned UniqueID = Section->getUniqueID();
 305   ELFUniquingMap.erase(
 306       ELFSectionKey{Section->getSectionName(), GroupName, UniqueID});
 307   auto I = ELFUniquingMap.insert(std::make_pair(
 308                                      ELFSectionKey{Name, GroupName, UniqueID},
 309                                      Section))
 310                .first;
 311   StringRef CachedName = I->first.SectionName;
 312   const_cast<MCSectionELF *>(Section)->setSectionName(CachedName);
 313 }
 314
 315 MCSectionELF *MCContext::createELFSectionImpl(StringRef Section, unsigned Type,
 316                                               unsigned Flags, SectionKind K,
 317                                               unsigned EntrySize,
 318                                               const MCSymbolELF *Group,
 319                                               unsigned UniqueID,
 320                                               const MCSymbolELF *Associated) {
 321   MCSymbolELF *R;
 322   MCSymbol *&Sym = Symbols[Section];
 323   // A section symbol can not redefine regular symbols. There may be multiple
 324   // sections with the same name, in which case the first such section wins.
 325   if (Sym && Sym->isDefined() &&
 326       (!Sym->isInSection() || Sym->getSection().getBeginSymbol() != Sym))
 327     reportError(SMLoc(), "invalid symbol redefinition");
 328   if (Sym && Sym->isUndefined()) {
 329     R = cast<MCSymbolELF>(Sym);
 330   } else {
 331     auto NameIter = UsedNames.insert(std::make_pair(Section, false)).first;
 332     R = new (&*NameIter, *this) MCSymbolELF(&*NameIter, /*isTemporary*/ false);
 333     if (!Sym)
 334       Sym = R;
 335   }
 336   R->setBinding(ELF::STB_LOCAL);
 337   R->setType(ELF::STT_SECTION);
 338
 339   auto *Ret = new (ELFAllocator.Allocate()) MCSectionELF(
 340       Section, Type, Flags, K, EntrySize, Group, UniqueID, R, Associated);
 341
 342   auto *F = new MCDataFragment();
 343   Ret->getFragmentList().insert(Ret->begin(), F);
 344   F->setParent(Ret);
 345   R->setFragment(F);
 346
 347   return Ret;
 348 }
 349
 350 MCSectionELF *MCContext::createELFRelSection(const Twine &Name, unsigned Type,
 351                                              unsigned Flags, unsigned EntrySize,
 352                                              const MCSymbolELF *Group,
 353                                              const MCSectionELF *RelInfoSection) {
 354   StringMap<bool>::iterator I;
 355   bool Inserted;
 356   std::tie(I, Inserted) =
 357       RelSecNames.insert(std::make_pair(Name.str(), true));
 358
 359   return createELFSectionImpl(
 360       I->getKey(), Type, Flags, SectionKind::getReadOnly(), EntrySize, Group,
 361       true, cast<MCSymbolELF>(RelInfoSection->getBeginSymbol()));
 362 }
 363
 364 MCSectionELF *MCContext::getELFNamedSection(const Twine &Prefix,
 365                                             const Twine &Suffix, unsigned Type,
 366                                             unsigned Flags,
 367                                             unsigned EntrySize) {
 368   return getELFSection(Prefix + "." + Suffix, Type, Flags, EntrySize, Suffix);
 369 }
 370
 371 MCSectionELF *MCContext::getELFSection(const Twine &Section, unsigned Type,
 372                                        unsigned Flags, unsigned EntrySize,
 373                                        const Twine &Group, unsigned UniqueID,
 374                                        const MCSymbolELF *Associated) {
 375   MCSymbolELF *GroupSym = nullptr;
 376   if (!Group.isTriviallyEmpty() && !Group.str().empty())
 377     GroupSym = cast<MCSymbolELF>(getOrCreateSymbol(Group));
 378
 379   return getELFSection(Section, Type, Flags, EntrySize, GroupSym, UniqueID,
 380                        Associated);
 381 }
 382
 383 MCSectionELF *MCContext::getELFSection(const Twine &Section, unsigned Type,
 384                                        unsigned Flags, unsigned EntrySize,
 385                                        const MCSymbolELF *GroupSym,
 386                                        unsigned UniqueID,
 387                                        const MCSymbolELF *Associated) {
 388   StringRef Group = "";
 389   if (GroupSym)
 390     Group = GroupSym->getName();
 391   // Do the lookup, if we have a hit, return it.
 392   auto IterBool = ELFUniquingMap.insert(
 393       std::make_pair(ELFSectionKey{Section.str(), Group, UniqueID}, nullptr));
 394   auto &Entry = *IterBool.first;
 395   if (!IterBool.second)
 396     return Entry.second;
 397
 398   StringRef CachedName = Entry.first.SectionName;
 399
 400   SectionKind Kind;
 401   if (Flags & ELF::SHF_ARM_PURECODE)
 402     Kind = SectionKind::getExecuteOnly();
 403   else if (Flags & ELF::SHF_EXECINSTR)
 404     Kind = SectionKind::getText();
 405   else
 406     Kind = SectionKind::getReadOnly();
 407
 408   MCSectionELF *Result = createELFSectionImpl(
 409       CachedName, Type, Flags, Kind, EntrySize, GroupSym, UniqueID, Associated);
 410   Entry.second = Result;
 411   return Result;
 412 }
 413
 414 MCSectionELF *MCContext::createELFGroupSection(const MCSymbolELF *Group) {
 415   return createELFSectionImpl(".group", ELF::SHT_GROUP, 0,
 416                               SectionKind::getReadOnly(), 4, Group, ~0,
 417                               nullptr);
 418 }
 419
 420 MCSectionCOFF *MCContext::getCOFFSection(StringRef Section,
 421                                          unsigned Characteristics,
 422                                          SectionKind Kind,
 423                                          StringRef COMDATSymName, int Selection,
 424                                          unsigned UniqueID,
 425                                          const char *BeginSymName) {
 426   MCSymbol *COMDATSymbol = nullptr;
 427   if (!COMDATSymName.empty()) {
 428     COMDATSymbol = getOrCreateSymbol(COMDATSymName);
 429     COMDATSymName = COMDATSymbol->getName();
 430   }
 431
 432
 433   // Do the lookup, if we have a hit, return it.
 434   COFFSectionKey T{Section, COMDATSymName, Selection, UniqueID};
 435   auto IterBool = COFFUniquingMap.insert(std::make_pair(T, nullptr));
 436   auto Iter = IterBool.first;
 437   if (!IterBool.second)
 438     return Iter->second;
 439
 440   MCSymbol *Begin = nullptr;
 441   if (BeginSymName)
 442     Begin = createTempSymbol(BeginSymName, false);
 443
 444   StringRef CachedName = Iter->first.SectionName;
 445   MCSectionCOFF *Result = new (COFFAllocator.Allocate()) MCSectionCOFF(
 446       CachedName, Characteristics, COMDATSymbol, Selection, Kind, Begin);
 447
 448   Iter->second = Result;
 449   return Result;
 450 }
 451
 452 MCSectionCOFF *MCContext::getCOFFSection(StringRef Section,
 453                                          unsigned Characteristics,
 454                                          SectionKind Kind,
 455                                          const char *BeginSymName) {
 456   return getCOFFSection(Section, Characteristics, Kind, "", 0, GenericSectionID,
 457                         BeginSymName);
 458 }
 459
 460 MCSectionCOFF *MCContext::getCOFFSection(StringRef Section) {
 461   COFFSectionKey T{Section, "", 0, GenericSectionID};
 462   auto Iter = COFFUniquingMap.find(T);
 463   if (Iter == COFFUniquingMap.end())
 464     return nullptr;
 465   return Iter->second;
 466 }
 467
 468 MCSectionCOFF *MCContext::getAssociativeCOFFSection(MCSectionCOFF *Sec,
 469                                                     const MCSymbol *KeySym,
 470                                                     unsigned UniqueID) {
 471   // Return the normal section if we don't have to be associative or unique.
 472   if (!KeySym && UniqueID == GenericSectionID)
 473     return Sec;
 474
 475   // If we have a key symbol, make an associative section with the same name and
 476   // kind as the normal section.
 477   unsigned Characteristics = Sec->getCharacteristics();
 478   if (KeySym) {
 479     Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
 480     return getCOFFSection(Sec->getSectionName(), Characteristics,
 481                           Sec->getKind(), KeySym->getName(),
 482                           COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE, UniqueID);
 483   }
 484
 485   return getCOFFSection(Sec->getSectionName(), Characteristics, Sec->getKind(),
 486                         "", 0, UniqueID);
 487 }
 488
 489 MCSectionWasm *MCContext::getWasmSection(const Twine &Section, unsigned Type,
 490                                          const Twine &Group, unsigned UniqueID,
 491                                          const char *BeginSymName) {
 492   MCSymbolWasm *GroupSym = nullptr;
 493   if (!Group.isTriviallyEmpty() && !Group.str().empty())
 494     GroupSym = cast<MCSymbolWasm>(getOrCreateSymbol(Group));
 495
 496   return getWasmSection(Section, Type, GroupSym, UniqueID, BeginSymName);
 497 }
 498
 499 MCSectionWasm *MCContext::getWasmSection(const Twine &Section, unsigned Type,
 500                                          const MCSymbolWasm *GroupSym,
 501                                          unsigned UniqueID,
 502                                          const char *BeginSymName) {
 503   StringRef Group = "";
 504   if (GroupSym)
 505     Group = GroupSym->getName();
 506   // Do the lookup, if we have a hit, return it.
 507   auto IterBool = WasmUniquingMap.insert(
 508       std::make_pair(WasmSectionKey{Section.str(), Group, UniqueID}, nullptr));
 509   auto &Entry = *IterBool.first;
 510   if (!IterBool.second)
 511     return Entry.second;
 512
 513   StringRef CachedName = Entry.first.SectionName;
 514
 515   SectionKind Kind = SectionKind::getText();
 516
 517   MCSymbol *Begin = nullptr;
 518   if (BeginSymName)
 519     Begin = createTempSymbol(BeginSymName, false);
 520
 521   MCSectionWasm *Result = new (WasmAllocator.Allocate())
 522       MCSectionWasm(CachedName, Type, Kind, GroupSym, UniqueID, Begin);
 523   Entry.second = Result;
 524   return Result;
 525 }
 526
 527 MCSubtargetInfo &MCContext::getSubtargetCopy(const MCSubtargetInfo &STI) {
 528   return *new (MCSubtargetAllocator.Allocate()) MCSubtargetInfo(STI);
 529 }
 530
 531 //===----------------------------------------------------------------------===//
 532 // Dwarf Management
 533 //===----------------------------------------------------------------------===//
 534
 535 /// getDwarfFile - takes a file name an number to place in the dwarf file and
 536 /// directory tables.  If the file number has already been allocated it is an
 537 /// error and zero is returned and the client reports the error, else the
 538 /// allocated file number is returned.  The file numbers may be in any order.
 539 unsigned MCContext::getDwarfFile(StringRef Directory, StringRef FileName,
 540                                  unsigned FileNumber, unsigned CUID) {
 541   MCDwarfLineTable &Table = MCDwarfLineTablesCUMap[CUID];
 542   return Table.getFile(Directory, FileName, FileNumber);
 543 }
 544
 545 /// isValidDwarfFileNumber - takes a dwarf file number and returns true if it
 546 /// currently is assigned and false otherwise.
 547 bool MCContext::isValidDwarfFileNumber(unsigned FileNumber, unsigned CUID) {
 548   const SmallVectorImpl<MCDwarfFile> &MCDwarfFiles = getMCDwarfFiles(CUID);
 549   if (FileNumber == 0 || FileNumber >= MCDwarfFiles.size())
 550     return false;
 551
 552   return !MCDwarfFiles[FileNumber].Name.empty();
 553 }
 554
 555 /// Remove empty sections from SectionStartEndSyms, to avoid generating
 556 /// useless debug info for them.
 557 void MCContext::finalizeDwarfSections(MCStreamer &MCOS) {
 558   SectionsForRanges.remove_if(
 559       [&](MCSection *Sec) { return !MCOS.mayHaveInstructions(*Sec); });
 560 }
 561
 562 CodeViewContext &MCContext::getCVContext() {
 563   if (!CVContext.get())
 564     CVContext.reset(new CodeViewContext);
 565   return *CVContext.get();
 566 }
 567
 568 //===----------------------------------------------------------------------===//
 569 // Error Reporting
 570 //===----------------------------------------------------------------------===//
 571
 572 void MCContext::reportError(SMLoc Loc, const Twine &Msg) {
 573   HadError = true;
 574
 575   // If we have a source manager use it. Otherwise, try using the inline source
 576   // manager.
 577   // If that fails, use the generic report_fatal_error().
 578   if (SrcMgr)
 579     SrcMgr->PrintMessage(Loc, SourceMgr::DK_Error, Msg);
 580   else if (InlineSrcMgr)
 581     InlineSrcMgr->PrintMessage(Loc, SourceMgr::DK_Error, Msg);
 582   else
 583     report_fatal_error(Msg, false);
 584 }
 585
 586 void MCContext::reportFatalError(SMLoc Loc, const Twine &Msg) {
 587   reportError(Loc, Msg);
 588
 589   // If we reached here, we are failing ungracefully. Run the interrupt handlers
 590   // to make sure any special cleanups get done, in particular that we remove
 591   // files registered with RemoveFileOnSignal.
 592   sys::RunInterruptHandlers();
 593   exit(1);
 594 }