xref: /freebsd/contrib/llvm-project/llvm/lib/MC/MCContext.cpp (revision 0d8fe2373503aeac48492f28073049a8bfa4feb5) 
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/BinaryFormat/XCOFF.h"
19 #include "llvm/MC/MCAsmInfo.h"
20 #include "llvm/MC/MCCodeView.h"
21 #include "llvm/MC/MCDwarf.h"
22 #include "llvm/MC/MCExpr.h"
23 #include "llvm/MC/MCFragment.h"
24 #include "llvm/MC/MCLabel.h"
25 #include "llvm/MC/MCObjectFileInfo.h"
26 #include "llvm/MC/MCSectionCOFF.h"
27 #include "llvm/MC/MCSectionELF.h"
28 #include "llvm/MC/MCSectionMachO.h"
29 #include "llvm/MC/MCSectionWasm.h"
30 #include "llvm/MC/MCSectionXCOFF.h"
31 #include "llvm/MC/MCStreamer.h"
32 #include "llvm/MC/MCSymbol.h"
33 #include "llvm/MC/MCSymbolCOFF.h"
34 #include "llvm/MC/MCSymbolELF.h"
35 #include "llvm/MC/MCSymbolMachO.h"
36 #include "llvm/MC/MCSymbolWasm.h"
37 #include "llvm/MC/MCSymbolXCOFF.h"
38 #include "llvm/MC/SectionKind.h"
39 #include "llvm/Support/Casting.h"
40 #include "llvm/Support/CommandLine.h"
41 #include "llvm/Support/ErrorHandling.h"
42 #include "llvm/Support/MemoryBuffer.h"
43 #include "llvm/Support/Path.h"
44 #include "llvm/Support/Signals.h"
45 #include "llvm/Support/SourceMgr.h"
46 #include "llvm/Support/raw_ostream.h"
47 #include <cassert>
48 #include <cstdlib>
49 #include <tuple>
50 #include <utility>
51 
52 using namespace llvm;
53 
54 static cl::opt<char*>
55 AsSecureLogFileName("as-secure-log-file-name",
56         cl::desc("As secure log file name (initialized from "
57                  "AS_SECURE_LOG_FILE env variable)"),
58         cl::init(getenv("AS_SECURE_LOG_FILE")), cl::Hidden);
59 
60 MCContext::MCContext(const MCAsmInfo *mai, const MCRegisterInfo *mri,
61                      const MCObjectFileInfo *mofi, const SourceMgr *mgr,
62                      MCTargetOptions const *TargetOpts, bool DoAutoReset)
63     : SrcMgr(mgr), InlineSrcMgr(nullptr), MAI(mai), MRI(mri), MOFI(mofi),
64       Symbols(Allocator), UsedNames(Allocator),
65       InlineAsmUsedLabelNames(Allocator),
66       CurrentDwarfLoc(0, 0, 0, DWARF2_FLAG_IS_STMT, 0, 0),
67       AutoReset(DoAutoReset), TargetOptions(TargetOpts) {
68   SecureLogFile = AsSecureLogFileName;
69 
70   if (SrcMgr && SrcMgr->getNumBuffers())
71     MainFileName = std::string(SrcMgr->getMemoryBuffer(SrcMgr->getMainFileID())
72                                    ->getBufferIdentifier());
73 }
74 
75 MCContext::~MCContext() {
76   if (AutoReset)
77     reset();
78 
79   // NOTE: The symbols are all allocated out of a bump pointer allocator,
80   // we don't need to free them here.
81 }
82 
83 //===----------------------------------------------------------------------===//
84 // Module Lifetime Management
85 //===----------------------------------------------------------------------===//
86 
87 void MCContext::reset() {
88   // Call the destructors so the fragments are freed
89   COFFAllocator.DestroyAll();
90   ELFAllocator.DestroyAll();
91   MachOAllocator.DestroyAll();
92   XCOFFAllocator.DestroyAll();
93   MCInstAllocator.DestroyAll();
94 
95   MCSubtargetAllocator.DestroyAll();
96   InlineAsmUsedLabelNames.clear();
97   UsedNames.clear();
98   Symbols.clear();
99   Allocator.Reset();
100   Instances.clear();
101   CompilationDir.clear();
102   MainFileName.clear();
103   MCDwarfLineTablesCUMap.clear();
104   SectionsForRanges.clear();
105   MCGenDwarfLabelEntries.clear();
106   DwarfDebugFlags = StringRef();
107   DwarfCompileUnitID = 0;
108   CurrentDwarfLoc = MCDwarfLoc(0, 0, 0, DWARF2_FLAG_IS_STMT, 0, 0);
109 
110   CVContext.reset();
111 
112   MachOUniquingMap.clear();
113   ELFUniquingMap.clear();
114   COFFUniquingMap.clear();
115   WasmUniquingMap.clear();
116   XCOFFUniquingMap.clear();
117 
118   ELFEntrySizeMap.clear();
119   ELFSeenGenericMergeableSections.clear();
120 
121   NextID.clear();
122   AllowTemporaryLabels = true;
123   DwarfLocSeen = false;
124   GenDwarfForAssembly = false;
125   GenDwarfFileNumber = 0;
126 
127   HadError = false;
128 }
129 
130 //===----------------------------------------------------------------------===//
131 // MCInst Management
132 //===----------------------------------------------------------------------===//
133 
134 MCInst *MCContext::createMCInst() {
135   return new (MCInstAllocator.Allocate()) MCInst;
136 }
137 
138 //===----------------------------------------------------------------------===//
139 // Symbol Manipulation
140 //===----------------------------------------------------------------------===//
141 
142 MCSymbol *MCContext::getOrCreateSymbol(const Twine &Name) {
143   SmallString<128> NameSV;
144   StringRef NameRef = Name.toStringRef(NameSV);
145 
146   assert(!NameRef.empty() && "Normal symbols cannot be unnamed!");
147 
148   MCSymbol *&Sym = Symbols[NameRef];
149   if (!Sym)
150     Sym = createSymbol(NameRef, false, false);
151 
152   return Sym;
153 }
154 
155 MCSymbol *MCContext::getOrCreateFrameAllocSymbol(StringRef FuncName,
156                                                  unsigned Idx) {
157   return getOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) + FuncName +
158                            "$frame_escape_" + Twine(Idx));
159 }
160 
161 MCSymbol *MCContext::getOrCreateParentFrameOffsetSymbol(StringRef FuncName) {
162   return getOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) + FuncName +
163                            "$parent_frame_offset");
164 }
165 
166 MCSymbol *MCContext::getOrCreateLSDASymbol(StringRef FuncName) {
167   return getOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) + "__ehtable$" +
168                            FuncName);
169 }
170 
171 MCSymbol *MCContext::createSymbolImpl(const StringMapEntry<bool> *Name,
172                                       bool IsTemporary) {
173   static_assert(std::is_trivially_destructible<MCSymbolCOFF>(),
174                 "MCSymbol classes must be trivially destructible");
175   static_assert(std::is_trivially_destructible<MCSymbolELF>(),
176                 "MCSymbol classes must be trivially destructible");
177   static_assert(std::is_trivially_destructible<MCSymbolMachO>(),
178                 "MCSymbol classes must be trivially destructible");
179   static_assert(std::is_trivially_destructible<MCSymbolWasm>(),
180                 "MCSymbol classes must be trivially destructible");
181   static_assert(std::is_trivially_destructible<MCSymbolXCOFF>(),
182                 "MCSymbol classes must be trivially destructible");
183   if (MOFI) {
184     switch (MOFI->getObjectFileType()) {
185     case MCObjectFileInfo::IsCOFF:
186       return new (Name, *this) MCSymbolCOFF(Name, IsTemporary);
187     case MCObjectFileInfo::IsELF:
188       return new (Name, *this) MCSymbolELF(Name, IsTemporary);
189     case MCObjectFileInfo::IsMachO:
190       return new (Name, *this) MCSymbolMachO(Name, IsTemporary);
191     case MCObjectFileInfo::IsWasm:
192       return new (Name, *this) MCSymbolWasm(Name, IsTemporary);
193     case MCObjectFileInfo::IsXCOFF:
194       return createXCOFFSymbolImpl(Name, IsTemporary);
195     }
196   }
197   return new (Name, *this) MCSymbol(MCSymbol::SymbolKindUnset, Name,
198                                     IsTemporary);
199 }
200 
201 MCSymbol *MCContext::createSymbol(StringRef Name, bool AlwaysAddSuffix,
202                                   bool CanBeUnnamed) {
203   if (CanBeUnnamed && !UseNamesOnTempLabels)
204     return createSymbolImpl(nullptr, true);
205 
206   // Determine whether this is a user written assembler temporary or normal
207   // label, if used.
208   bool IsTemporary = CanBeUnnamed;
209   if (AllowTemporaryLabels && !IsTemporary)
210     IsTemporary = Name.startswith(MAI->getPrivateGlobalPrefix());
211 
212   SmallString<128> NewName = Name;
213   bool AddSuffix = AlwaysAddSuffix;
214   unsigned &NextUniqueID = NextID[Name];
215   while (true) {
216     if (AddSuffix) {
217       NewName.resize(Name.size());
218       raw_svector_ostream(NewName) << NextUniqueID++;
219     }
220     auto NameEntry = UsedNames.insert(std::make_pair(NewName, true));
221     if (NameEntry.second || !NameEntry.first->second) {
222       // Ok, we found a name.
223       // Mark it as used for a non-section symbol.
224       NameEntry.first->second = true;
225       // Have the MCSymbol object itself refer to the copy of the string that is
226       // embedded in the UsedNames entry.
227       return createSymbolImpl(&*NameEntry.first, IsTemporary);
228     }
229     assert(IsTemporary && "Cannot rename non-temporary symbols");
230     AddSuffix = true;
231   }
232   llvm_unreachable("Infinite loop");
233 }
234 
235 MCSymbol *MCContext::createTempSymbol(const Twine &Name, bool AlwaysAddSuffix) {
236   SmallString<128> NameSV;
237   raw_svector_ostream(NameSV) << MAI->getPrivateGlobalPrefix() << Name;
238   return createSymbol(NameSV, AlwaysAddSuffix, true);
239 }
240 
241 MCSymbol *MCContext::createNamedTempSymbol(const Twine &Name) {
242   SmallString<128> NameSV;
243   raw_svector_ostream(NameSV) << MAI->getPrivateGlobalPrefix() << Name;
244   return createSymbol(NameSV, true, false);
245 }
246 
247 MCSymbol *MCContext::createLinkerPrivateTempSymbol() {
248   SmallString<128> NameSV;
249   raw_svector_ostream(NameSV) << MAI->getLinkerPrivateGlobalPrefix() << "tmp";
250   return createSymbol(NameSV, true, false);
251 }
252 
253 MCSymbol *MCContext::createTempSymbol() { return createTempSymbol("tmp"); }
254 
255 MCSymbol *MCContext::createNamedTempSymbol() {
256   return createNamedTempSymbol("tmp");
257 }
258 
259 unsigned MCContext::NextInstance(unsigned LocalLabelVal) {
260   MCLabel *&Label = Instances[LocalLabelVal];
261   if (!Label)
262     Label = new (*this) MCLabel(0);
263   return Label->incInstance();
264 }
265 
266 unsigned MCContext::GetInstance(unsigned LocalLabelVal) {
267   MCLabel *&Label = Instances[LocalLabelVal];
268   if (!Label)
269     Label = new (*this) MCLabel(0);
270   return Label->getInstance();
271 }
272 
273 MCSymbol *MCContext::getOrCreateDirectionalLocalSymbol(unsigned LocalLabelVal,
274                                                        unsigned Instance) {
275   MCSymbol *&Sym = LocalSymbols[std::make_pair(LocalLabelVal, Instance)];
276   if (!Sym)
277     Sym = createNamedTempSymbol();
278   return Sym;
279 }
280 
281 MCSymbol *MCContext::createDirectionalLocalSymbol(unsigned LocalLabelVal) {
282   unsigned Instance = NextInstance(LocalLabelVal);
283   return getOrCreateDirectionalLocalSymbol(LocalLabelVal, Instance);
284 }
285 
286 MCSymbol *MCContext::getDirectionalLocalSymbol(unsigned LocalLabelVal,
287                                                bool Before) {
288   unsigned Instance = GetInstance(LocalLabelVal);
289   if (!Before)
290     ++Instance;
291   return getOrCreateDirectionalLocalSymbol(LocalLabelVal, Instance);
292 }
293 
294 MCSymbol *MCContext::lookupSymbol(const Twine &Name) const {
295   SmallString<128> NameSV;
296   StringRef NameRef = Name.toStringRef(NameSV);
297   return Symbols.lookup(NameRef);
298 }
299 
300 void MCContext::setSymbolValue(MCStreamer &Streamer,
301                               StringRef Sym,
302                               uint64_t Val) {
303   auto Symbol = getOrCreateSymbol(Sym);
304   Streamer.emitAssignment(Symbol, MCConstantExpr::create(Val, *this));
305 }
306 
307 void MCContext::registerInlineAsmLabel(MCSymbol *Sym) {
308   InlineAsmUsedLabelNames[Sym->getName()] = Sym;
309 }
310 
311 MCSymbolXCOFF *
312 MCContext::createXCOFFSymbolImpl(const StringMapEntry<bool> *Name,
313                                  bool IsTemporary) {
314   if (!Name)
315     return new (nullptr, *this) MCSymbolXCOFF(nullptr, IsTemporary);
316 
317   StringRef OriginalName = Name->first();
318   if (OriginalName.startswith("._Renamed..") ||
319       OriginalName.startswith("_Renamed.."))
320     reportError(SMLoc(), "invalid symbol name from source");
321 
322   if (MAI->isValidUnquotedName(OriginalName))
323     return new (Name, *this) MCSymbolXCOFF(Name, IsTemporary);
324 
325   // Now we have a name that contains invalid character(s) for XCOFF symbol.
326   // Let's replace with something valid, but save the original name so that
327   // we could still use the original name in the symbol table.
328   SmallString<128> InvalidName(OriginalName);
329 
330   // If it's an entry point symbol, we will keep the '.'
331   // in front for the convention purpose. Otherwise, add "_Renamed.."
332   // as prefix to signal this is an renamed symbol.
333   const bool IsEntryPoint = !InvalidName.empty() && InvalidName[0] == '.';
334   SmallString<128> ValidName =
335       StringRef(IsEntryPoint ? "._Renamed.." : "_Renamed..");
336 
337   // Append the hex values of '_' and invalid characters with "_Renamed..";
338   // at the same time replace invalid characters with '_'.
339   for (size_t I = 0; I < InvalidName.size(); ++I) {
340     if (!MAI->isAcceptableChar(InvalidName[I]) || InvalidName[I] == '_') {
341       raw_svector_ostream(ValidName).write_hex(InvalidName[I]);
342       InvalidName[I] = '_';
343     }
344   }
345 
346   // Skip entry point symbol's '.' as we already have a '.' in front of
347   // "_Renamed".
348   if (IsEntryPoint)
349     ValidName.append(InvalidName.substr(1, InvalidName.size() - 1));
350   else
351     ValidName.append(InvalidName);
352 
353   auto NameEntry = UsedNames.insert(std::make_pair(ValidName, true));
354   assert((NameEntry.second || !NameEntry.first->second) &&
355          "This name is used somewhere else.");
356   // Mark the name as used for a non-section symbol.
357   NameEntry.first->second = true;
358   // Have the MCSymbol object itself refer to the copy of the string
359   // that is embedded in the UsedNames entry.
360   MCSymbolXCOFF *XSym = new (&*NameEntry.first, *this)
361       MCSymbolXCOFF(&*NameEntry.first, IsTemporary);
362   XSym->setSymbolTableName(MCSymbolXCOFF::getUnqualifiedName(OriginalName));
363   return XSym;
364 }
365 
366 //===----------------------------------------------------------------------===//
367 // Section Management
368 //===----------------------------------------------------------------------===//
369 
370 MCSectionMachO *MCContext::getMachOSection(StringRef Segment, StringRef Section,
371                                            unsigned TypeAndAttributes,
372                                            unsigned Reserved2, SectionKind Kind,
373                                            const char *BeginSymName) {
374   // We unique sections by their segment/section pair.  The returned section
375   // may not have the same flags as the requested section, if so this should be
376   // diagnosed by the client as an error.
377 
378   // Form the name to look up.
379   assert(Section.size() <= 16 && "section name is too long");
380   assert(!memchr(Section.data(), '\0', Section.size()) &&
381          "section name cannot contain NUL");
382 
383   // Do the lookup, if we have a hit, return it.
384   auto R = MachOUniquingMap.try_emplace((Segment + Twine(',') + Section).str());
385   if (!R.second)
386     return R.first->second;
387 
388   MCSymbol *Begin = nullptr;
389   if (BeginSymName)
390     Begin = createTempSymbol(BeginSymName, false);
391 
392   // Otherwise, return a new section.
393   StringRef Name = R.first->first();
394   R.first->second = new (MachOAllocator.Allocate())
395       MCSectionMachO(Segment, Name.substr(Name.size() - Section.size()),
396                      TypeAndAttributes, Reserved2, Kind, Begin);
397   return R.first->second;
398 }
399 
400 void MCContext::renameELFSection(MCSectionELF *Section, StringRef Name) {
401   StringRef GroupName;
402   if (const MCSymbol *Group = Section->getGroup())
403     GroupName = Group->getName();
404 
405   // This function is only used by .debug*, which should not have the
406   // SHF_LINK_ORDER flag.
407   unsigned UniqueID = Section->getUniqueID();
408   ELFUniquingMap.erase(
409       ELFSectionKey{Section->getName(), GroupName, "", UniqueID});
410   auto I = ELFUniquingMap
411                .insert(std::make_pair(
412                    ELFSectionKey{Name, GroupName, "", UniqueID}, Section))
413                .first;
414   StringRef CachedName = I->first.SectionName;
415   const_cast<MCSectionELF *>(Section)->setSectionName(CachedName);
416 }
417 
418 MCSectionELF *MCContext::createELFSectionImpl(StringRef Section, unsigned Type,
419                                               unsigned Flags, SectionKind K,
420                                               unsigned EntrySize,
421                                               const MCSymbolELF *Group,
422                                               unsigned UniqueID,
423                                               const MCSymbolELF *LinkedToSym) {
424   MCSymbolELF *R;
425   MCSymbol *&Sym = Symbols[Section];
426   // A section symbol can not redefine regular symbols. There may be multiple
427   // sections with the same name, in which case the first such section wins.
428   if (Sym && Sym->isDefined() &&
429       (!Sym->isInSection() || Sym->getSection().getBeginSymbol() != Sym))
430     reportError(SMLoc(), "invalid symbol redefinition");
431   if (Sym && Sym->isUndefined()) {
432     R = cast<MCSymbolELF>(Sym);
433   } else {
434     auto NameIter = UsedNames.insert(std::make_pair(Section, false)).first;
435     R = new (&*NameIter, *this) MCSymbolELF(&*NameIter, /*isTemporary*/ false);
436     if (!Sym)
437       Sym = R;
438   }
439   R->setBinding(ELF::STB_LOCAL);
440   R->setType(ELF::STT_SECTION);
441 
442   auto *Ret = new (ELFAllocator.Allocate()) MCSectionELF(
443       Section, Type, Flags, K, EntrySize, Group, UniqueID, R, LinkedToSym);
444 
445   auto *F = new MCDataFragment();
446   Ret->getFragmentList().insert(Ret->begin(), F);
447   F->setParent(Ret);
448   R->setFragment(F);
449 
450   return Ret;
451 }
452 
453 MCSectionELF *MCContext::createELFRelSection(const Twine &Name, unsigned Type,
454                                              unsigned Flags, unsigned EntrySize,
455                                              const MCSymbolELF *Group,
456                                              const MCSectionELF *RelInfoSection) {
457   StringMap<bool>::iterator I;
458   bool Inserted;
459   std::tie(I, Inserted) =
460       RelSecNames.insert(std::make_pair(Name.str(), true));
461 
462   return createELFSectionImpl(
463       I->getKey(), Type, Flags, SectionKind::getReadOnly(), EntrySize, Group,
464       true, cast<MCSymbolELF>(RelInfoSection->getBeginSymbol()));
465 }
466 
467 MCSectionELF *MCContext::getELFNamedSection(const Twine &Prefix,
468                                             const Twine &Suffix, unsigned Type,
469                                             unsigned Flags,
470                                             unsigned EntrySize) {
471   return getELFSection(Prefix + "." + Suffix, Type, Flags, EntrySize, Suffix);
472 }
473 
474 MCSectionELF *MCContext::getELFSection(const Twine &Section, unsigned Type,
475                                        unsigned Flags, unsigned EntrySize,
476                                        const Twine &Group, unsigned UniqueID,
477                                        const MCSymbolELF *LinkedToSym) {
478   MCSymbolELF *GroupSym = nullptr;
479   if (!Group.isTriviallyEmpty() && !Group.str().empty())
480     GroupSym = cast<MCSymbolELF>(getOrCreateSymbol(Group));
481 
482   return getELFSection(Section, Type, Flags, EntrySize, GroupSym, UniqueID,
483                        LinkedToSym);
484 }
485 
486 MCSectionELF *MCContext::getELFSection(const Twine &Section, unsigned Type,
487                                        unsigned Flags, unsigned EntrySize,
488                                        const MCSymbolELF *GroupSym,
489                                        unsigned UniqueID,
490                                        const MCSymbolELF *LinkedToSym) {
491   StringRef Group = "";
492   if (GroupSym)
493     Group = GroupSym->getName();
494   assert(!(LinkedToSym && LinkedToSym->getName().empty()));
495   // Do the lookup, if we have a hit, return it.
496   auto IterBool = ELFUniquingMap.insert(std::make_pair(
497       ELFSectionKey{Section.str(), Group,
498                     LinkedToSym ? LinkedToSym->getName() : "", UniqueID},
499       nullptr));
500   auto &Entry = *IterBool.first;
501   if (!IterBool.second)
502     return Entry.second;
503 
504   StringRef CachedName = Entry.first.SectionName;
505 
506   SectionKind Kind;
507   if (Flags & ELF::SHF_ARM_PURECODE)
508     Kind = SectionKind::getExecuteOnly();
509   else if (Flags & ELF::SHF_EXECINSTR)
510     Kind = SectionKind::getText();
511   else
512     Kind = SectionKind::getReadOnly();
513 
514   MCSectionELF *Result =
515       createELFSectionImpl(CachedName, Type, Flags, Kind, EntrySize, GroupSym,
516                            UniqueID, LinkedToSym);
517   Entry.second = Result;
518 
519   recordELFMergeableSectionInfo(Result->getName(), Result->getFlags(),
520                                 Result->getUniqueID(), Result->getEntrySize());
521 
522   return Result;
523 }
524 
525 MCSectionELF *MCContext::createELFGroupSection(const MCSymbolELF *Group) {
526   return createELFSectionImpl(".group", ELF::SHT_GROUP, 0,
527                               SectionKind::getReadOnly(), 4, Group,
528                               MCSection::NonUniqueID, nullptr);
529 }
530 
531 void MCContext::recordELFMergeableSectionInfo(StringRef SectionName,
532                                               unsigned Flags, unsigned UniqueID,
533                                               unsigned EntrySize) {
534   bool IsMergeable = Flags & ELF::SHF_MERGE;
535   if (IsMergeable && (UniqueID == GenericSectionID))
536     ELFSeenGenericMergeableSections.insert(SectionName);
537 
538   // For mergeable sections or non-mergeable sections with a generic mergeable
539   // section name we enter their Unique ID into the ELFEntrySizeMap so that
540   // compatible globals can be assigned to the same section.
541   if (IsMergeable || isELFGenericMergeableSection(SectionName)) {
542     ELFEntrySizeMap.insert(std::make_pair(
543         ELFEntrySizeKey{SectionName, Flags, EntrySize}, UniqueID));
544   }
545 }
546 
547 bool MCContext::isELFImplicitMergeableSectionNamePrefix(StringRef SectionName) {
548   return SectionName.startswith(".rodata.str") ||
549          SectionName.startswith(".rodata.cst");
550 }
551 
552 bool MCContext::isELFGenericMergeableSection(StringRef SectionName) {
553   return isELFImplicitMergeableSectionNamePrefix(SectionName) ||
554          ELFSeenGenericMergeableSections.count(SectionName);
555 }
556 
557 Optional<unsigned> MCContext::getELFUniqueIDForEntsize(StringRef SectionName,
558                                                        unsigned Flags,
559                                                        unsigned EntrySize) {
560   auto I = ELFEntrySizeMap.find(
561       MCContext::ELFEntrySizeKey{SectionName, Flags, EntrySize});
562   return (I != ELFEntrySizeMap.end()) ? Optional<unsigned>(I->second) : None;
563 }
564 
565 MCSectionCOFF *MCContext::getCOFFSection(StringRef Section,
566                                          unsigned Characteristics,
567                                          SectionKind Kind,
568                                          StringRef COMDATSymName, int Selection,
569                                          unsigned UniqueID,
570                                          const char *BeginSymName) {
571   MCSymbol *COMDATSymbol = nullptr;
572   if (!COMDATSymName.empty()) {
573     COMDATSymbol = getOrCreateSymbol(COMDATSymName);
574     COMDATSymName = COMDATSymbol->getName();
575   }
576 
577 
578   // Do the lookup, if we have a hit, return it.
579   COFFSectionKey T{Section, COMDATSymName, Selection, UniqueID};
580   auto IterBool = COFFUniquingMap.insert(std::make_pair(T, nullptr));
581   auto Iter = IterBool.first;
582   if (!IterBool.second)
583     return Iter->second;
584 
585   MCSymbol *Begin = nullptr;
586   if (BeginSymName)
587     Begin = createTempSymbol(BeginSymName, false);
588 
589   StringRef CachedName = Iter->first.SectionName;
590   MCSectionCOFF *Result = new (COFFAllocator.Allocate()) MCSectionCOFF(
591       CachedName, Characteristics, COMDATSymbol, Selection, Kind, Begin);
592 
593   Iter->second = Result;
594   return Result;
595 }
596 
597 MCSectionCOFF *MCContext::getCOFFSection(StringRef Section,
598                                          unsigned Characteristics,
599                                          SectionKind Kind,
600                                          const char *BeginSymName) {
601   return getCOFFSection(Section, Characteristics, Kind, "", 0, GenericSectionID,
602                         BeginSymName);
603 }
604 
605 MCSectionCOFF *MCContext::getAssociativeCOFFSection(MCSectionCOFF *Sec,
606                                                     const MCSymbol *KeySym,
607                                                     unsigned UniqueID) {
608   // Return the normal section if we don't have to be associative or unique.
609   if (!KeySym && UniqueID == GenericSectionID)
610     return Sec;
611 
612   // If we have a key symbol, make an associative section with the same name and
613   // kind as the normal section.
614   unsigned Characteristics = Sec->getCharacteristics();
615   if (KeySym) {
616     Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
617     return getCOFFSection(Sec->getName(), Characteristics, Sec->getKind(),
618                           KeySym->getName(),
619                           COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE, UniqueID);
620   }
621 
622   return getCOFFSection(Sec->getName(), Characteristics, Sec->getKind(), "", 0,
623                         UniqueID);
624 }
625 
626 MCSectionWasm *MCContext::getWasmSection(const Twine &Section, SectionKind K,
627                                          const Twine &Group, unsigned UniqueID,
628                                          const char *BeginSymName) {
629   MCSymbolWasm *GroupSym = nullptr;
630   if (!Group.isTriviallyEmpty() && !Group.str().empty()) {
631     GroupSym = cast<MCSymbolWasm>(getOrCreateSymbol(Group));
632     GroupSym->setComdat(true);
633   }
634 
635   return getWasmSection(Section, K, GroupSym, UniqueID, BeginSymName);
636 }
637 
638 MCSectionWasm *MCContext::getWasmSection(const Twine &Section, SectionKind Kind,
639                                          const MCSymbolWasm *GroupSym,
640                                          unsigned UniqueID,
641                                          const char *BeginSymName) {
642   StringRef Group = "";
643   if (GroupSym)
644     Group = GroupSym->getName();
645   // Do the lookup, if we have a hit, return it.
646   auto IterBool = WasmUniquingMap.insert(
647       std::make_pair(WasmSectionKey{Section.str(), Group, UniqueID}, nullptr));
648   auto &Entry = *IterBool.first;
649   if (!IterBool.second)
650     return Entry.second;
651 
652   StringRef CachedName = Entry.first.SectionName;
653 
654   MCSymbol *Begin = createSymbol(CachedName, true, false);
655   cast<MCSymbolWasm>(Begin)->setType(wasm::WASM_SYMBOL_TYPE_SECTION);
656 
657   MCSectionWasm *Result = new (WasmAllocator.Allocate())
658       MCSectionWasm(CachedName, Kind, GroupSym, UniqueID, Begin);
659   Entry.second = Result;
660 
661   auto *F = new MCDataFragment();
662   Result->getFragmentList().insert(Result->begin(), F);
663   F->setParent(Result);
664   Begin->setFragment(F);
665 
666   return Result;
667 }
668 
669 MCSectionXCOFF *
670 MCContext::getXCOFFSection(StringRef Section, XCOFF::StorageMappingClass SMC,
671                            XCOFF::SymbolType Type, SectionKind Kind,
672                            bool MultiSymbolsAllowed, const char *BeginSymName) {
673   // Do the lookup. If we have a hit, return it.
674   auto IterBool = XCOFFUniquingMap.insert(
675       std::make_pair(XCOFFSectionKey{Section.str(), SMC}, nullptr));
676   auto &Entry = *IterBool.first;
677   if (!IterBool.second) {
678     MCSectionXCOFF *ExistedEntry = Entry.second;
679     if (ExistedEntry->isMultiSymbolsAllowed() != MultiSymbolsAllowed)
680       report_fatal_error("section's multiply symbols policy does not match");
681 
682     return ExistedEntry;
683   }
684 
685   // Otherwise, return a new section.
686   StringRef CachedName = Entry.first.SectionName;
687   MCSymbolXCOFF *QualName = cast<MCSymbolXCOFF>(getOrCreateSymbol(
688       CachedName + "[" + XCOFF::getMappingClassString(SMC) + "]"));
689 
690   MCSymbol *Begin = nullptr;
691   if (BeginSymName)
692     Begin = createTempSymbol(BeginSymName, false);
693 
694   // QualName->getUnqualifiedName() and CachedName are the same except when
695   // CachedName contains invalid character(s) such as '$' for an XCOFF symbol.
696   MCSectionXCOFF *Result = new (XCOFFAllocator.Allocate())
697       MCSectionXCOFF(QualName->getUnqualifiedName(), SMC, Type, Kind, QualName,
698                      Begin, CachedName, MultiSymbolsAllowed);
699   Entry.second = Result;
700 
701   auto *F = new MCDataFragment();
702   Result->getFragmentList().insert(Result->begin(), F);
703   F->setParent(Result);
704 
705   if (Begin)
706     Begin->setFragment(F);
707 
708   return Result;
709 }
710 
711 MCSubtargetInfo &MCContext::getSubtargetCopy(const MCSubtargetInfo &STI) {
712   return *new (MCSubtargetAllocator.Allocate()) MCSubtargetInfo(STI);
713 }
714 
715 void MCContext::addDebugPrefixMapEntry(const std::string &From,
716                                        const std::string &To) {
717   DebugPrefixMap.insert(std::make_pair(From, To));
718 }
719 
720 void MCContext::RemapDebugPaths() {
721   const auto &DebugPrefixMap = this->DebugPrefixMap;
722   if (DebugPrefixMap.empty())
723     return;
724 
725   const auto RemapDebugPath = [&DebugPrefixMap](std::string &Path) {
726     SmallString<256> P(Path);
727     for (const auto &Entry : DebugPrefixMap) {
728       if (llvm::sys::path::replace_path_prefix(P, Entry.first, Entry.second)) {
729         Path = P.str().str();
730         break;
731       }
732     }
733   };
734 
735   // Remap compilation directory.
736   std::string CompDir = std::string(CompilationDir.str());
737   RemapDebugPath(CompDir);
738   CompilationDir = CompDir;
739 
740   // Remap MCDwarfDirs in all compilation units.
741   for (auto &CUIDTablePair : MCDwarfLineTablesCUMap)
742     for (auto &Dir : CUIDTablePair.second.getMCDwarfDirs())
743       RemapDebugPath(Dir);
744 }
745 
746 //===----------------------------------------------------------------------===//
747 // Dwarf Management
748 //===----------------------------------------------------------------------===//
749 
750 void MCContext::setGenDwarfRootFile(StringRef InputFileName, StringRef Buffer) {
751   // MCDwarf needs the root file as well as the compilation directory.
752   // If we find a '.file 0' directive that will supersede these values.
753   Optional<MD5::MD5Result> Cksum;
754   if (getDwarfVersion() >= 5) {
755     MD5 Hash;
756     MD5::MD5Result Sum;
757     Hash.update(Buffer);
758     Hash.final(Sum);
759     Cksum = Sum;
760   }
761   // Canonicalize the root filename. It cannot be empty, and should not
762   // repeat the compilation dir.
763   // The MCContext ctor initializes MainFileName to the name associated with
764   // the SrcMgr's main file ID, which might be the same as InputFileName (and
765   // possibly include directory components).
766   // Or, MainFileName might have been overridden by a -main-file-name option,
767   // which is supposed to be just a base filename with no directory component.
768   // So, if the InputFileName and MainFileName are not equal, assume
769   // MainFileName is a substitute basename and replace the last component.
770   SmallString<1024> FileNameBuf = InputFileName;
771   if (FileNameBuf.empty() || FileNameBuf == "-")
772     FileNameBuf = "<stdin>";
773   if (!getMainFileName().empty() && FileNameBuf != getMainFileName()) {
774     llvm::sys::path::remove_filename(FileNameBuf);
775     llvm::sys::path::append(FileNameBuf, getMainFileName());
776   }
777   StringRef FileName = FileNameBuf;
778   if (FileName.consume_front(getCompilationDir()))
779     if (llvm::sys::path::is_separator(FileName.front()))
780       FileName = FileName.drop_front();
781   assert(!FileName.empty());
782   setMCLineTableRootFile(
783       /*CUID=*/0, getCompilationDir(), FileName, Cksum, None);
784 }
785 
786 /// getDwarfFile - takes a file name and number to place in the dwarf file and
787 /// directory tables.  If the file number has already been allocated it is an
788 /// error and zero is returned and the client reports the error, else the
789 /// allocated file number is returned.  The file numbers may be in any order.
790 Expected<unsigned> MCContext::getDwarfFile(StringRef Directory,
791                                            StringRef FileName,
792                                            unsigned FileNumber,
793                                            Optional<MD5::MD5Result> Checksum,
794                                            Optional<StringRef> Source,
795                                            unsigned CUID) {
796   MCDwarfLineTable &Table = MCDwarfLineTablesCUMap[CUID];
797   return Table.tryGetFile(Directory, FileName, Checksum, Source, DwarfVersion,
798                           FileNumber);
799 }
800 
801 /// isValidDwarfFileNumber - takes a dwarf file number and returns true if it
802 /// currently is assigned and false otherwise.
803 bool MCContext::isValidDwarfFileNumber(unsigned FileNumber, unsigned CUID) {
804   const MCDwarfLineTable &LineTable = getMCDwarfLineTable(CUID);
805   if (FileNumber == 0)
806     return getDwarfVersion() >= 5;
807   if (FileNumber >= LineTable.getMCDwarfFiles().size())
808     return false;
809 
810   return !LineTable.getMCDwarfFiles()[FileNumber].Name.empty();
811 }
812 
813 /// Remove empty sections from SectionsForRanges, to avoid generating
814 /// useless debug info for them.
815 void MCContext::finalizeDwarfSections(MCStreamer &MCOS) {
816   SectionsForRanges.remove_if(
817       [&](MCSection *Sec) { return !MCOS.mayHaveInstructions(*Sec); });
818 }
819 
820 CodeViewContext &MCContext::getCVContext() {
821   if (!CVContext.get())
822     CVContext.reset(new CodeViewContext);
823   return *CVContext.get();
824 }
825 
826 //===----------------------------------------------------------------------===//
827 // Error Reporting
828 //===----------------------------------------------------------------------===//
829 
830 void MCContext::reportError(SMLoc Loc, const Twine &Msg) {
831   HadError = true;
832 
833   // If we have a source manager use it. Otherwise, try using the inline source
834   // manager.
835   // If that fails, construct a temporary SourceMgr.
836   if (SrcMgr)
837     SrcMgr->PrintMessage(Loc, SourceMgr::DK_Error, Msg);
838   else if (InlineSrcMgr)
839     InlineSrcMgr->PrintMessage(Loc, SourceMgr::DK_Error, Msg);
840   else
841     SourceMgr().PrintMessage(Loc, SourceMgr::DK_Error, Msg);
842 }
843 
844 void MCContext::reportWarning(SMLoc Loc, const Twine &Msg) {
845   if (TargetOptions && TargetOptions->MCNoWarn)
846     return;
847   if (TargetOptions && TargetOptions->MCFatalWarnings)
848     reportError(Loc, Msg);
849   else {
850     // If we have a source manager use it. Otherwise, try using the inline
851     // source manager.
852     if (SrcMgr)
853       SrcMgr->PrintMessage(Loc, SourceMgr::DK_Warning, Msg);
854     else if (InlineSrcMgr)
855       InlineSrcMgr->PrintMessage(Loc, SourceMgr::DK_Warning, Msg);
856   }
857 }
858 
859 void MCContext::reportFatalError(SMLoc Loc, const Twine &Msg) {
860   reportError(Loc, Msg);
861 
862   // If we reached here, we are failing ungracefully. Run the interrupt handlers
863   // to make sure any special cleanups get done, in particular that we remove
864   // files registered with RemoveFileOnSignal.
865   sys::RunInterruptHandlers();
866   exit(1);
867 }
868