lib/MC/MCContext.cpp

   1 //===- lib/MC/MCContext.cpp - Machine Code Context ------------------------===//
   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/MCContext.h"
  10 #include "llvm/ADT/Optional.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/MCSectionXCOFF.h"
  30 #include "llvm/MC/MCStreamer.h"
  31 #include "llvm/MC/MCSymbol.h"
  32 #include "llvm/MC/MCSymbolCOFF.h"
  33 #include "llvm/MC/MCSymbolELF.h"
  34 #include "llvm/MC/MCSymbolMachO.h"
  35 #include "llvm/MC/MCSymbolWasm.h"
  36 #include "llvm/MC/MCSymbolXCOFF.h"
  37 #include "llvm/MC/SectionKind.h"
  38 #include "llvm/Support/Casting.h"
  39 #include "llvm/Support/CommandLine.h"
  40 #include "llvm/Support/ErrorHandling.h"
  41 #include "llvm/Support/MemoryBuffer.h"
  42 #include "llvm/Support/Path.h"
  43 #include "llvm/Support/Signals.h"
  44 #include "llvm/Support/SourceMgr.h"
  45 #include "llvm/Support/raw_ostream.h"
  46 #include <cassert>
  47 #include <cstdlib>
  48 #include <tuple>
  49 #include <utility>
  50
  51 using namespace llvm;
  52
  53 static cl::opt<char*>
  54 AsSecureLogFileName("as-secure-log-file-name",
  55         cl::desc("As secure log file name (initialized from "
  56                  "AS_SECURE_LOG_FILE env variable)"),
  57         cl::init(getenv("AS_SECURE_LOG_FILE")), cl::Hidden);
  58
  59 MCContext::MCContext(const MCAsmInfo *mai, const MCRegisterInfo *mri,
  60                      const MCObjectFileInfo *mofi, const SourceMgr *mgr,
  61                      MCTargetOptions const *TargetOpts, bool DoAutoReset)
  62     : SrcMgr(mgr), InlineSrcMgr(nullptr), MAI(mai), MRI(mri), MOFI(mofi),
  63       Symbols(Allocator), UsedNames(Allocator),
  64       InlineAsmUsedLabelNames(Allocator),
  65       CurrentDwarfLoc(0, 0, 0, DWARF2_FLAG_IS_STMT, 0, 0),
  66       AutoReset(DoAutoReset), TargetOptions(TargetOpts) {
  67   SecureLogFile = AsSecureLogFileName;
  68
  69   if (SrcMgr && SrcMgr->getNumBuffers())
  70     MainFileName =
  71         SrcMgr->getMemoryBuffer(SrcMgr->getMainFileID())->getBufferIdentifier();
  72 }
  73
  74 MCContext::~MCContext() {
  75   if (AutoReset)
  76     reset();
  77
  78   // NOTE: The symbols are all allocated out of a bump pointer allocator,
  79   // we don't need to free them here.
  80 }
  81
  82 //===----------------------------------------------------------------------===//
  83 // Module Lifetime Management
  84 //===----------------------------------------------------------------------===//
  85
  86 void MCContext::reset() {
  87   // Call the destructors so the fragments are freed
  88   COFFAllocator.DestroyAll();
  89   ELFAllocator.DestroyAll();
  90   MachOAllocator.DestroyAll();
  91   XCOFFAllocator.DestroyAll();
  92
  93   MCSubtargetAllocator.DestroyAll();
  94   InlineAsmUsedLabelNames.clear();
  95   UsedNames.clear();
  96   Symbols.clear();
  97   Allocator.Reset();
  98   Instances.clear();
  99   CompilationDir.clear();
 100   MainFileName.clear();
 101   MCDwarfLineTablesCUMap.clear();
 102   SectionsForRanges.clear();
 103   MCGenDwarfLabelEntries.clear();
 104   DwarfDebugFlags = StringRef();
 105   DwarfCompileUnitID = 0;
 106   CurrentDwarfLoc = MCDwarfLoc(0, 0, 0, DWARF2_FLAG_IS_STMT, 0, 0);
 107
 108   CVContext.reset();
 109
 110   MachOUniquingMap.clear();
 111   ELFUniquingMap.clear();
 112   COFFUniquingMap.clear();
 113   WasmUniquingMap.clear();
 114   XCOFFUniquingMap.clear();
 115
 116   NextID.clear();
 117   AllowTemporaryLabels = true;
 118   DwarfLocSeen = false;
 119   GenDwarfForAssembly = false;
 120   GenDwarfFileNumber = 0;
 121
 122   HadError = false;
 123 }
 124
 125 //===----------------------------------------------------------------------===//
 126 // Symbol Manipulation
 127 //===----------------------------------------------------------------------===//
 128
 129 MCSymbol *MCContext::getOrCreateSymbol(const Twine &Name) {
 130   SmallString<128> NameSV;
 131   StringRef NameRef = Name.toStringRef(NameSV);
 132
 133   assert(!NameRef.empty() && "Normal symbols cannot be unnamed!");
 134
 135   MCSymbol *&Sym = Symbols[NameRef];
 136   if (!Sym)
 137     Sym = createSymbol(NameRef, false, false);
 138
 139   return Sym;
 140 }
 141
 142 MCSymbol *MCContext::getOrCreateFrameAllocSymbol(StringRef FuncName,
 143                                                  unsigned Idx) {
 144   return getOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) + FuncName +
 145                            "$frame_escape_" + Twine(Idx));
 146 }
 147
 148 MCSymbol *MCContext::getOrCreateParentFrameOffsetSymbol(StringRef FuncName) {
 149   return getOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) + FuncName +
 150                            "$parent_frame_offset");
 151 }
 152
 153 MCSymbol *MCContext::getOrCreateLSDASymbol(StringRef FuncName) {
 154   return getOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) + "__ehtable$" +
 155                            FuncName);
 156 }
 157
 158 MCSymbol *MCContext::createSymbolImpl(const StringMapEntry<bool> *Name,
 159                                       bool IsTemporary) {
 160   if (MOFI) {
 161     switch (MOFI->getObjectFileType()) {
 162     case MCObjectFileInfo::IsCOFF:
 163       return new (Name, *this) MCSymbolCOFF(Name, IsTemporary);
 164     case MCObjectFileInfo::IsELF:
 165       return new (Name, *this) MCSymbolELF(Name, IsTemporary);
 166     case MCObjectFileInfo::IsMachO:
 167       return new (Name, *this) MCSymbolMachO(Name, IsTemporary);
 168     case MCObjectFileInfo::IsWasm:
 169       return new (Name, *this) MCSymbolWasm(Name, IsTemporary);
 170     case MCObjectFileInfo::IsXCOFF:
 171       return new (Name, *this) MCSymbolXCOFF(Name, IsTemporary);
 172     }
 173   }
 174   return new (Name, *this) MCSymbol(MCSymbol::SymbolKindUnset, Name,
 175                                     IsTemporary);
 176 }
 177
 178 MCSymbol *MCContext::createSymbol(StringRef Name, bool AlwaysAddSuffix,
 179                                   bool CanBeUnnamed) {
 180   if (CanBeUnnamed && !UseNamesOnTempLabels)
 181     return createSymbolImpl(nullptr, true);
 182
 183   // Determine whether this is a user written assembler temporary or normal
 184   // label, if used.
 185   bool IsTemporary = CanBeUnnamed;
 186   if (AllowTemporaryLabels && !IsTemporary)
 187     IsTemporary = Name.startswith(MAI->getPrivateGlobalPrefix());
 188
 189   SmallString<128> NewName = Name;
 190   bool AddSuffix = AlwaysAddSuffix;
 191   unsigned &NextUniqueID = NextID[Name];
 192   while (true) {
 193     if (AddSuffix) {
 194       NewName.resize(Name.size());
 195       raw_svector_ostream(NewName) << NextUniqueID++;
 196     }
 197     auto NameEntry = UsedNames.insert(std::make_pair(NewName, true));
 198     if (NameEntry.second || !NameEntry.first->second) {
 199       // Ok, we found a name.
 200       // Mark it as used for a non-section symbol.
 201       NameEntry.first->second = true;
 202       // Have the MCSymbol object itself refer to the copy of the string that is
 203       // embedded in the UsedNames entry.
 204       return createSymbolImpl(&*NameEntry.first, IsTemporary);
 205     }
 206     assert(IsTemporary && "Cannot rename non-temporary symbols");
 207     AddSuffix = true;
 208   }
 209   llvm_unreachable("Infinite loop");
 210 }
 211
 212 MCSymbol *MCContext::createTempSymbol(const Twine &Name, bool AlwaysAddSuffix,
 213                                       bool CanBeUnnamed) {
 214   SmallString<128> NameSV;
 215   raw_svector_ostream(NameSV) << MAI->getPrivateGlobalPrefix() << Name;
 216   return createSymbol(NameSV, AlwaysAddSuffix, CanBeUnnamed);
 217 }
 218
 219 MCSymbol *MCContext::createLinkerPrivateTempSymbol() {
 220   SmallString<128> NameSV;
 221   raw_svector_ostream(NameSV) << MAI->getLinkerPrivateGlobalPrefix() << "tmp";
 222   return createSymbol(NameSV, true, false);
 223 }
 224
 225 MCSymbol *MCContext::createTempSymbol(bool CanBeUnnamed) {
 226   return createTempSymbol("tmp", true, CanBeUnnamed);
 227 }
 228
 229 unsigned MCContext::NextInstance(unsigned LocalLabelVal) {
 230   MCLabel *&Label = Instances[LocalLabelVal];
 231   if (!Label)
 232     Label = new (*this) MCLabel(0);
 233   return Label->incInstance();
 234 }
 235
 236 unsigned MCContext::GetInstance(unsigned LocalLabelVal) {
 237   MCLabel *&Label = Instances[LocalLabelVal];
 238   if (!Label)
 239     Label = new (*this) MCLabel(0);
 240   return Label->getInstance();
 241 }
 242
 243 MCSymbol *MCContext::getOrCreateDirectionalLocalSymbol(unsigned LocalLabelVal,
 244                                                        unsigned Instance) {
 245   MCSymbol *&Sym = LocalSymbols[std::make_pair(LocalLabelVal, Instance)];
 246   if (!Sym)
 247     Sym = createTempSymbol(false);
 248   return Sym;
 249 }
 250
 251 MCSymbol *MCContext::createDirectionalLocalSymbol(unsigned LocalLabelVal) {
 252   unsigned Instance = NextInstance(LocalLabelVal);
 253   return getOrCreateDirectionalLocalSymbol(LocalLabelVal, Instance);
 254 }
 255
 256 MCSymbol *MCContext::getDirectionalLocalSymbol(unsigned LocalLabelVal,
 257                                                bool Before) {
 258   unsigned Instance = GetInstance(LocalLabelVal);
 259   if (!Before)
 260     ++Instance;
 261   return getOrCreateDirectionalLocalSymbol(LocalLabelVal, Instance);
 262 }
 263
 264 MCSymbol *MCContext::lookupSymbol(const Twine &Name) const {
 265   SmallString<128> NameSV;
 266   StringRef NameRef = Name.toStringRef(NameSV);
 267   return Symbols.lookup(NameRef);
 268 }
 269
 270 void MCContext::setSymbolValue(MCStreamer &Streamer,
 271                               StringRef Sym,
 272                               uint64_t Val) {
 273   auto Symbol = getOrCreateSymbol(Sym);
 274   Streamer.EmitAssignment(Symbol, MCConstantExpr::create(Val, *this));
 275 }
 276
 277 void MCContext::registerInlineAsmLabel(MCSymbol *Sym) {
 278   InlineAsmUsedLabelNames[Sym->getName()] = Sym;
 279 }
 280
 281 //===----------------------------------------------------------------------===//
 282 // Section Management
 283 //===----------------------------------------------------------------------===//
 284
 285 MCSectionMachO *MCContext::getMachOSection(StringRef Segment, StringRef Section,
 286                                            unsigned TypeAndAttributes,
 287                                            unsigned Reserved2, SectionKind Kind,
 288                                            const char *BeginSymName) {
 289   // We unique sections by their segment/section pair.  The returned section
 290   // may not have the same flags as the requested section, if so this should be
 291   // diagnosed by the client as an error.
 292
 293   // Form the name to look up.
 294   SmallString<64> Name;
 295   Name += Segment;
 296   Name.push_back(',');
 297   Name += Section;
 298
 299   // Do the lookup, if we have a hit, return it.
 300   MCSectionMachO *&Entry = MachOUniquingMap[Name];
 301   if (Entry)
 302     return Entry;
 303
 304   MCSymbol *Begin = nullptr;
 305   if (BeginSymName)
 306     Begin = createTempSymbol(BeginSymName, false);
 307
 308   // Otherwise, return a new section.
 309   return Entry = new (MachOAllocator.Allocate()) MCSectionMachO(
 310              Segment, Section, TypeAndAttributes, Reserved2, Kind, Begin);
 311 }
 312
 313 void MCContext::renameELFSection(MCSectionELF *Section, StringRef Name) {
 314   StringRef GroupName;
 315   if (const MCSymbol *Group = Section->getGroup())
 316     GroupName = Group->getName();
 317
 318   unsigned UniqueID = Section->getUniqueID();
 319   ELFUniquingMap.erase(
 320       ELFSectionKey{Section->getSectionName(), GroupName, UniqueID});
 321   auto I = ELFUniquingMap.insert(std::make_pair(
 322                                      ELFSectionKey{Name, GroupName, UniqueID},
 323                                      Section))
 324                .first;
 325   StringRef CachedName = I->first.SectionName;
 326   const_cast<MCSectionELF *>(Section)->setSectionName(CachedName);
 327 }
 328
 329 MCSectionELF *MCContext::createELFSectionImpl(StringRef Section, unsigned Type,
 330                                               unsigned Flags, SectionKind K,
 331                                               unsigned EntrySize,
 332                                               const MCSymbolELF *Group,
 333                                               unsigned UniqueID,
 334                                               const MCSymbolELF *Associated) {
 335   MCSymbolELF *R;
 336   MCSymbol *&Sym = Symbols[Section];
 337   // A section symbol can not redefine regular symbols. There may be multiple
 338   // sections with the same name, in which case the first such section wins.
 339   if (Sym && Sym->isDefined() &&
 340       (!Sym->isInSection() || Sym->getSection().getBeginSymbol() != Sym))
 341     reportError(SMLoc(), "invalid symbol redefinition");
 342   if (Sym && Sym->isUndefined()) {
 343     R = cast<MCSymbolELF>(Sym);
 344   } else {
 345     auto NameIter = UsedNames.insert(std::make_pair(Section, false)).first;
 346     R = new (&*NameIter, *this) MCSymbolELF(&*NameIter, /*isTemporary*/ false);
 347     if (!Sym)
 348       Sym = R;
 349   }
 350   R->setBinding(ELF::STB_LOCAL);
 351   R->setType(ELF::STT_SECTION);
 352
 353   auto *Ret = new (ELFAllocator.Allocate()) MCSectionELF(
 354       Section, Type, Flags, K, EntrySize, Group, UniqueID, R, Associated);
 355
 356   auto *F = new MCDataFragment();
 357   Ret->getFragmentList().insert(Ret->begin(), F);
 358   F->setParent(Ret);
 359   R->setFragment(F);
 360
 361   return Ret;
 362 }
 363
 364 MCSectionELF *MCContext::createELFRelSection(const Twine &Name, unsigned Type,
 365                                              unsigned Flags, unsigned EntrySize,
 366                                              const MCSymbolELF *Group,
 367                                              const MCSectionELF *RelInfoSection) {
 368   StringMap<bool>::iterator I;
 369   bool Inserted;
 370   std::tie(I, Inserted) =
 371       RelSecNames.insert(std::make_pair(Name.str(), true));
 372
 373   return createELFSectionImpl(
 374       I->getKey(), Type, Flags, SectionKind::getReadOnly(), EntrySize, Group,
 375       true, cast<MCSymbolELF>(RelInfoSection->getBeginSymbol()));
 376 }
 377
 378 MCSectionELF *MCContext::getELFNamedSection(const Twine &Prefix,
 379                                             const Twine &Suffix, unsigned Type,
 380                                             unsigned Flags,
 381                                             unsigned EntrySize) {
 382   return getELFSection(Prefix + "." + Suffix, Type, Flags, EntrySize, Suffix);
 383 }
 384
 385 MCSectionELF *MCContext::getELFSection(const Twine &Section, unsigned Type,
 386                                        unsigned Flags, unsigned EntrySize,
 387                                        const Twine &Group, unsigned UniqueID,
 388                                        const MCSymbolELF *Associated) {
 389   MCSymbolELF *GroupSym = nullptr;
 390   if (!Group.isTriviallyEmpty() && !Group.str().empty())
 391     GroupSym = cast<MCSymbolELF>(getOrCreateSymbol(Group));
 392
 393   return getELFSection(Section, Type, Flags, EntrySize, GroupSym, UniqueID,
 394                        Associated);
 395 }
 396
 397 MCSectionELF *MCContext::getELFSection(const Twine &Section, unsigned Type,
 398                                        unsigned Flags, unsigned EntrySize,
 399                                        const MCSymbolELF *GroupSym,
 400                                        unsigned UniqueID,
 401                                        const MCSymbolELF *Associated) {
 402   StringRef Group = "";
 403   if (GroupSym)
 404     Group = GroupSym->getName();
 405   // Do the lookup, if we have a hit, return it.
 406   auto IterBool = ELFUniquingMap.insert(
 407       std::make_pair(ELFSectionKey{Section.str(), Group, UniqueID}, nullptr));
 408   auto &Entry = *IterBool.first;
 409   if (!IterBool.second)
 410     return Entry.second;
 411
 412   StringRef CachedName = Entry.first.SectionName;
 413
 414   SectionKind Kind;
 415   if (Flags & ELF::SHF_ARM_PURECODE)
 416     Kind = SectionKind::getExecuteOnly();
 417   else if (Flags & ELF::SHF_EXECINSTR)
 418     Kind = SectionKind::getText();
 419   else
 420     Kind = SectionKind::getReadOnly();
 421
 422   MCSectionELF *Result = createELFSectionImpl(
 423       CachedName, Type, Flags, Kind, EntrySize, GroupSym, UniqueID, Associated);
 424   Entry.second = Result;
 425   return Result;
 426 }
 427
 428 MCSectionELF *MCContext::createELFGroupSection(const MCSymbolELF *Group) {
 429   return createELFSectionImpl(".group", ELF::SHT_GROUP, 0,
 430                               SectionKind::getReadOnly(), 4, Group, ~0,
 431                               nullptr);
 432 }
 433
 434 MCSectionCOFF *MCContext::getCOFFSection(StringRef Section,
 435                                          unsigned Characteristics,
 436                                          SectionKind Kind,
 437                                          StringRef COMDATSymName, int Selection,
 438                                          unsigned UniqueID,
 439                                          const char *BeginSymName) {
 440   MCSymbol *COMDATSymbol = nullptr;
 441   if (!COMDATSymName.empty()) {
 442     COMDATSymbol = getOrCreateSymbol(COMDATSymName);
 443     COMDATSymName = COMDATSymbol->getName();
 444   }
 445
 446
 447   // Do the lookup, if we have a hit, return it.
 448   COFFSectionKey T{Section, COMDATSymName, Selection, UniqueID};
 449   auto IterBool = COFFUniquingMap.insert(std::make_pair(T, nullptr));
 450   auto Iter = IterBool.first;
 451   if (!IterBool.second)
 452     return Iter->second;
 453
 454   MCSymbol *Begin = nullptr;
 455   if (BeginSymName)
 456     Begin = createTempSymbol(BeginSymName, false);
 457
 458   StringRef CachedName = Iter->first.SectionName;
 459   MCSectionCOFF *Result = new (COFFAllocator.Allocate()) MCSectionCOFF(
 460       CachedName, Characteristics, COMDATSymbol, Selection, Kind, Begin);
 461
 462   Iter->second = Result;
 463   return Result;
 464 }
 465
 466 MCSectionCOFF *MCContext::getCOFFSection(StringRef Section,
 467                                          unsigned Characteristics,
 468                                          SectionKind Kind,
 469                                          const char *BeginSymName) {
 470   return getCOFFSection(Section, Characteristics, Kind, "", 0, GenericSectionID,
 471                         BeginSymName);
 472 }
 473
 474 MCSectionCOFF *MCContext::getAssociativeCOFFSection(MCSectionCOFF *Sec,
 475                                                     const MCSymbol *KeySym,
 476                                                     unsigned UniqueID) {
 477   // Return the normal section if we don't have to be associative or unique.
 478   if (!KeySym && UniqueID == GenericSectionID)
 479     return Sec;
 480
 481   // If we have a key symbol, make an associative section with the same name and
 482   // kind as the normal section.
 483   unsigned Characteristics = Sec->getCharacteristics();
 484   if (KeySym) {
 485     Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
 486     return getCOFFSection(Sec->getSectionName(), Characteristics,
 487                           Sec->getKind(), KeySym->getName(),
 488                           COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE, UniqueID);
 489   }
 490
 491   return getCOFFSection(Sec->getSectionName(), Characteristics, Sec->getKind(),
 492                         "", 0, UniqueID);
 493 }
 494
 495 MCSectionWasm *MCContext::getWasmSection(const Twine &Section, SectionKind K,
 496                                          const Twine &Group, unsigned UniqueID,
 497                                          const char *BeginSymName) {
 498   MCSymbolWasm *GroupSym = nullptr;
 499   if (!Group.isTriviallyEmpty() && !Group.str().empty()) {
 500     GroupSym = cast<MCSymbolWasm>(getOrCreateSymbol(Group));
 501     GroupSym->setComdat(true);
 502   }
 503
 504   return getWasmSection(Section, K, GroupSym, UniqueID, BeginSymName);
 505 }
 506
 507 MCSectionWasm *MCContext::getWasmSection(const Twine &Section, SectionKind Kind,
 508                                          const MCSymbolWasm *GroupSym,
 509                                          unsigned UniqueID,
 510                                          const char *BeginSymName) {
 511   StringRef Group = "";
 512   if (GroupSym)
 513     Group = GroupSym->getName();
 514   // Do the lookup, if we have a hit, return it.
 515   auto IterBool = WasmUniquingMap.insert(
 516       std::make_pair(WasmSectionKey{Section.str(), Group, UniqueID}, nullptr));
 517   auto &Entry = *IterBool.first;
 518   if (!IterBool.second)
 519     return Entry.second;
 520
 521   StringRef CachedName = Entry.first.SectionName;
 522
 523   MCSymbol *Begin = createSymbol(CachedName, false, false);
 524   cast<MCSymbolWasm>(Begin)->setType(wasm::WASM_SYMBOL_TYPE_SECTION);
 525
 526   MCSectionWasm *Result = new (WasmAllocator.Allocate())
 527       MCSectionWasm(CachedName, Kind, GroupSym, UniqueID, Begin);
 528   Entry.second = Result;
 529
 530   auto *F = new MCDataFragment();
 531   Result->getFragmentList().insert(Result->begin(), F);
 532   F->setParent(Result);
 533   Begin->setFragment(F);
 534
 535   return Result;
 536 }
 537
 538 MCSectionXCOFF *MCContext::getXCOFFSection(StringRef Section,
 539                                            XCOFF::StorageMappingClass SMC,
 540                                            XCOFF::SymbolType Type,
 541                                            SectionKind Kind,
 542                                            const char *BeginSymName) {
 543   // Do the lookup. If we have a hit, return it.
 544   auto IterBool = XCOFFUniquingMap.insert(
 545       std::make_pair(XCOFFSectionKey{Section.str(), SMC}, nullptr));
 546   auto &Entry = *IterBool.first;
 547   if (!IterBool.second)
 548     return Entry.second;
 549
 550   // Otherwise, return a new section.
 551   StringRef CachedName = Entry.first.SectionName;
 552
 553   MCSymbol *Begin = nullptr;
 554   if (BeginSymName)
 555     Begin = createTempSymbol(BeginSymName, false);
 556
 557   MCSectionXCOFF *Result = new (XCOFFAllocator.Allocate())
 558       MCSectionXCOFF(CachedName, SMC, Type, Kind, Begin);
 559   Entry.second = Result;
 560
 561   auto *F = new MCDataFragment();
 562   Result->getFragmentList().insert(Result->begin(), F);
 563   F->setParent(Result);
 564
 565   if (Begin)
 566     Begin->setFragment(F);
 567
 568   return Result;
 569 }
 570
 571 MCSubtargetInfo &MCContext::getSubtargetCopy(const MCSubtargetInfo &STI) {
 572   return *new (MCSubtargetAllocator.Allocate()) MCSubtargetInfo(STI);
 573 }
 574
 575 void MCContext::addDebugPrefixMapEntry(const std::string &From,
 576                                        const std::string &To) {
 577   DebugPrefixMap.insert(std::make_pair(From, To));
 578 }
 579
 580 void MCContext::RemapDebugPaths() {
 581   const auto &DebugPrefixMap = this->DebugPrefixMap;
 582   const auto RemapDebugPath = [&DebugPrefixMap](std::string &Path) {
 583     for (const auto &Entry : DebugPrefixMap)
 584       if (StringRef(Path).startswith(Entry.first)) {
 585         std::string RemappedPath =
 586             (Twine(Entry.second) + Path.substr(Entry.first.size())).str();
 587         Path.swap(RemappedPath);
 588       }
 589   };
 590
 591   // Remap compilation directory.
 592   std::string CompDir = CompilationDir.str();
 593   RemapDebugPath(CompDir);
 594   CompilationDir = CompDir;
 595
 596   // Remap MCDwarfDirs in all compilation units.
 597   for (auto &CUIDTablePair : MCDwarfLineTablesCUMap)
 598     for (auto &Dir : CUIDTablePair.second.getMCDwarfDirs())
 599       RemapDebugPath(Dir);
 600 }
 601
 602 //===----------------------------------------------------------------------===//
 603 // Dwarf Management
 604 //===----------------------------------------------------------------------===//
 605
 606 void MCContext::setGenDwarfRootFile(StringRef InputFileName, StringRef Buffer) {
 607   // MCDwarf needs the root file as well as the compilation directory.
 608   // If we find a '.file 0' directive that will supersede these values.
 609   Optional<MD5::MD5Result> Cksum;
 610   if (getDwarfVersion() >= 5) {
 611     MD5 Hash;
 612     MD5::MD5Result Sum;
 613     Hash.update(Buffer);
 614     Hash.final(Sum);
 615     Cksum = Sum;
 616   }
 617   // Canonicalize the root filename. It cannot be empty, and should not
 618   // repeat the compilation dir.
 619   // The MCContext ctor initializes MainFileName to the name associated with
 620   // the SrcMgr's main file ID, which might be the same as InputFileName (and
 621   // possibly include directory components).
 622   // Or, MainFileName might have been overridden by a -main-file-name option,
 623   // which is supposed to be just a base filename with no directory component.
 624   // So, if the InputFileName and MainFileName are not equal, assume
 625   // MainFileName is a substitute basename and replace the last component.
 626   SmallString<1024> FileNameBuf = InputFileName;
 627   if (FileNameBuf.empty() || FileNameBuf == "-")
 628     FileNameBuf = "<stdin>";
 629   if (!getMainFileName().empty() && FileNameBuf != getMainFileName()) {
 630     llvm::sys::path::remove_filename(FileNameBuf);
 631     llvm::sys::path::append(FileNameBuf, getMainFileName());
 632   }
 633   StringRef FileName = FileNameBuf;
 634   if (FileName.consume_front(getCompilationDir()))
 635     if (llvm::sys::path::is_separator(FileName.front()))
 636       FileName = FileName.drop_front();
 637   assert(!FileName.empty());
 638   setMCLineTableRootFile(
 639       /*CUID=*/0, getCompilationDir(), FileName, Cksum, None);
 640 }
 641
 642 /// getDwarfFile - takes a file name and number to place in the dwarf file and
 643 /// directory tables.  If the file number has already been allocated it is an
 644 /// error and zero is returned and the client reports the error, else the
 645 /// allocated file number is returned.  The file numbers may be in any order.
 646 Expected<unsigned> MCContext::getDwarfFile(StringRef Directory,
 647                                            StringRef FileName,
 648                                            unsigned FileNumber,
 649                                            Optional<MD5::MD5Result> Checksum,
 650                                            Optional<StringRef> Source,
 651                                            unsigned CUID) {
 652   MCDwarfLineTable &Table = MCDwarfLineTablesCUMap[CUID];
 653   return Table.tryGetFile(Directory, FileName, Checksum, Source, DwarfVersion,
 654                           FileNumber);
 655 }
 656
 657 /// isValidDwarfFileNumber - takes a dwarf file number and returns true if it
 658 /// currently is assigned and false otherwise.
 659 bool MCContext::isValidDwarfFileNumber(unsigned FileNumber, unsigned CUID) {
 660   const MCDwarfLineTable &LineTable = getMCDwarfLineTable(CUID);
 661   if (FileNumber == 0)
 662     return getDwarfVersion() >= 5;
 663   if (FileNumber >= LineTable.getMCDwarfFiles().size())
 664     return false;
 665
 666   return !LineTable.getMCDwarfFiles()[FileNumber].Name.empty();
 667 }
 668
 669 /// Remove empty sections from SectionsForRanges, to avoid generating
 670 /// useless debug info for them.
 671 void MCContext::finalizeDwarfSections(MCStreamer &MCOS) {
 672   SectionsForRanges.remove_if(
 673       [&](MCSection *Sec) { return !MCOS.mayHaveInstructions(*Sec); });
 674 }
 675
 676 CodeViewContext &MCContext::getCVContext() {
 677   if (!CVContext.get())
 678     CVContext.reset(new CodeViewContext);
 679   return *CVContext.get();
 680 }
 681
 682 //===----------------------------------------------------------------------===//
 683 // Error Reporting
 684 //===----------------------------------------------------------------------===//
 685
 686 void MCContext::reportError(SMLoc Loc, const Twine &Msg) {
 687   HadError = true;
 688
 689   // If we have a source manager use it. Otherwise, try using the inline source
 690   // manager.
 691   // If that fails, use the generic report_fatal_error().
 692   if (SrcMgr)
 693     SrcMgr->PrintMessage(Loc, SourceMgr::DK_Error, Msg);
 694   else if (InlineSrcMgr)
 695     InlineSrcMgr->PrintMessage(Loc, SourceMgr::DK_Error, Msg);
 696   else
 697     report_fatal_error(Msg, false);
 698 }
 699
 700 void MCContext::reportWarning(SMLoc Loc, const Twine &Msg) {
 701   if (TargetOptions && TargetOptions->MCNoWarn)
 702     return;
 703   if (TargetOptions && TargetOptions->MCFatalWarnings)
 704     reportError(Loc, Msg);
 705   else {
 706     // If we have a source manager use it. Otherwise, try using the inline
 707     // source manager.
 708     if (SrcMgr)
 709       SrcMgr->PrintMessage(Loc, SourceMgr::DK_Warning, Msg);
 710     else if (InlineSrcMgr)
 711       InlineSrcMgr->PrintMessage(Loc, SourceMgr::DK_Warning, Msg);
 712   }
 713 }
 714
 715 void MCContext::reportFatalError(SMLoc Loc, const Twine &Msg) {
 716   reportError(Loc, Msg);
 717
 718   // If we reached here, we are failing ungracefully. Run the interrupt handlers
 719   // to make sure any special cleanups get done, in particular that we remove
 720   // files registered with RemoveFileOnSignal.
 721   sys::RunInterruptHandlers();
 722   exit(1);
 723 }