1 //===- tools/dsymutil/DwarfLinker.cpp - Dwarf debug info linker -----------===//
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "BinaryHolder.h"
13 #include "MachOUtils.h"
14 #include "NonRelocatableStringpool.h"
15 #include "llvm/ADT/IntervalMap.h"
16 #include "llvm/ADT/StringMap.h"
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/CodeGen/AsmPrinter.h"
19 #include "llvm/CodeGen/DIE.h"
20 #include "llvm/Config/config.h"
21 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
22 #include "llvm/DebugInfo/DWARF/DWARFDebugInfoEntry.h"
23 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
24 #include "llvm/MC/MCAsmBackend.h"
25 #include "llvm/MC/MCAsmInfo.h"
26 #include "llvm/MC/MCContext.h"
27 #include "llvm/MC/MCCodeEmitter.h"
28 #include "llvm/MC/MCDwarf.h"
29 #include "llvm/MC/MCInstrInfo.h"
30 #include "llvm/MC/MCObjectFileInfo.h"
31 #include "llvm/MC/MCRegisterInfo.h"
32 #include "llvm/MC/MCStreamer.h"
33 #include "llvm/MC/MCSubtargetInfo.h"
34 #include "llvm/Object/MachO.h"
35 #include "llvm/Support/Dwarf.h"
36 #include "llvm/Support/LEB128.h"
37 #include "llvm/Support/TargetRegistry.h"
38 #include "llvm/Target/TargetMachine.h"
39 #include "llvm/Target/TargetOptions.h"
48 template <typename KeyT, typename ValT>
49 using HalfOpenIntervalMap =
50 IntervalMap<KeyT, ValT, IntervalMapImpl::NodeSizer<KeyT, ValT>::LeafSize,
51 IntervalMapHalfOpenInfo<KeyT>>;
53 typedef HalfOpenIntervalMap<uint64_t, int64_t> FunctionIntervals;
55 // FIXME: Delete this structure.
56 struct PatchLocation {
57 DIE::value_iterator I;
59 PatchLocation() = default;
60 PatchLocation(DIE::value_iterator I) : I(I) {}
62 void set(uint64_t New) const {
65 assert(Old.getType() == DIEValue::isInteger);
66 *I = DIEValue(Old.getAttribute(), Old.getForm(), DIEInteger(New));
69 uint64_t get() const {
71 return I->getDIEInteger().getValue();
78 /// A DeclContext is a named program scope that is used for ODR
79 /// uniquing of types.
80 /// The set of DeclContext for the ODR-subject parts of a Dwarf link
81 /// is expanded (and uniqued) with each new object file processed. We
82 /// need to determine the context of each DIE in an linked object file
83 /// to see if the corresponding type has already been emitted.
85 /// The contexts are conceptually organised as a tree (eg. a function
86 /// scope is contained in a namespace scope that contains other
87 /// scopes), but storing/accessing them in an actual tree is too
88 /// inefficient: we need to be able to very quickly query a context
89 /// for a given child context by name. Storing a StringMap in each
90 /// DeclContext would be too space inefficient.
91 /// The solution here is to give each DeclContext a link to its parent
92 /// (this allows to walk up the tree), but to query the existance of a
93 /// specific DeclContext using a separate DenseMap keyed on the hash
94 /// of the fully qualified name of the context.
96 unsigned QualifiedNameHash;
102 const DeclContext &Parent;
103 const DWARFDebugInfoEntryMinimal *LastSeenDIE;
104 uint32_t LastSeenCompileUnitID;
105 uint32_t CanonicalDIEOffset;
110 typedef DenseSet<DeclContext *, DeclMapInfo> Map;
113 : QualifiedNameHash(0), Line(0), ByteSize(0),
114 Tag(dwarf::DW_TAG_compile_unit), Name(), File(), Parent(*this),
115 LastSeenDIE(nullptr), LastSeenCompileUnitID(0), CanonicalDIEOffset(0) {}
117 DeclContext(unsigned Hash, uint32_t Line, uint32_t ByteSize, uint16_t Tag,
118 StringRef Name, StringRef File, const DeclContext &Parent,
119 const DWARFDebugInfoEntryMinimal *LastSeenDIE = nullptr,
121 : QualifiedNameHash(Hash), Line(Line), ByteSize(ByteSize), Tag(Tag),
122 Name(Name), File(File), Parent(Parent), LastSeenDIE(LastSeenDIE),
123 LastSeenCompileUnitID(CUId), CanonicalDIEOffset(0) {}
125 uint32_t getQualifiedNameHash() const { return QualifiedNameHash; }
127 bool setLastSeenDIE(CompileUnit &U, const DWARFDebugInfoEntryMinimal *Die);
129 uint32_t getCanonicalDIEOffset() const { return CanonicalDIEOffset; }
130 void setCanonicalDIEOffset(uint32_t Offset) { CanonicalDIEOffset = Offset; }
132 uint16_t getTag() const { return Tag; }
133 StringRef getName() const { return Name; }
136 /// Info type for the DenseMap storing the DeclContext pointers.
137 struct DeclMapInfo : private DenseMapInfo<DeclContext *> {
138 using DenseMapInfo<DeclContext *>::getEmptyKey;
139 using DenseMapInfo<DeclContext *>::getTombstoneKey;
141 static unsigned getHashValue(const DeclContext *Ctxt) {
142 return Ctxt->QualifiedNameHash;
145 static bool isEqual(const DeclContext *LHS, const DeclContext *RHS) {
146 if (RHS == getEmptyKey() || RHS == getTombstoneKey())
148 return LHS->QualifiedNameHash == RHS->QualifiedNameHash &&
149 LHS->Line == RHS->Line && LHS->ByteSize == RHS->ByteSize &&
150 LHS->Name.data() == RHS->Name.data() &&
151 LHS->File.data() == RHS->File.data() &&
152 LHS->Parent.QualifiedNameHash == RHS->Parent.QualifiedNameHash;
156 /// This class gives a tree-like API to the DenseMap that stores the
157 /// DeclContext objects. It also holds the BumpPtrAllocator where
158 /// these objects will be allocated.
159 class DeclContextTree {
160 BumpPtrAllocator Allocator;
162 DeclContext::Map Contexts;
165 /// Get the child of \a Context described by \a DIE in \a Unit. The
166 /// required strings will be interned in \a StringPool.
167 /// \returns The child DeclContext along with one bit that is set if
168 /// this context is invalid.
169 /// FIXME: the invalid bit along the return value is to emulate some
170 /// dsymutil-classic functionality. See the fucntion definition for
171 /// a more thorough discussion of its use.
172 PointerIntPair<DeclContext *, 1>
173 getChildDeclContext(DeclContext &Context,
174 const DWARFDebugInfoEntryMinimal *DIE, CompileUnit &Unit,
175 NonRelocatableStringpool &StringPool);
177 DeclContext &getRoot() { return Root; }
180 /// \brief Stores all information relating to a compile unit, be it in
181 /// its original instance in the object file to its brand new cloned
182 /// and linked DIE tree.
185 /// \brief Information gathered about a DIE in the object file.
187 int64_t AddrAdjust; ///< Address offset to apply to the described entity.
188 DeclContext *Ctxt; ///< ODR Declaration context.
189 DIE *Clone; ///< Cloned version of that DIE.
190 uint32_t ParentIdx; ///< The index of this DIE's parent.
191 bool Keep : 1; ///< Is the DIE part of the linked output?
192 bool InDebugMap : 1;///< Was this DIE's entity found in the map?
193 bool Prune : 1; ///< Is this a pure forward declaration we can strip?
196 CompileUnit(DWARFUnit &OrigUnit, unsigned ID, bool CanUseODR,
197 StringRef ClangModuleName)
198 : OrigUnit(OrigUnit), ID(ID), LowPc(UINT64_MAX), HighPc(0), RangeAlloc(),
199 Ranges(RangeAlloc), ClangModuleName(ClangModuleName) {
200 Info.resize(OrigUnit.getNumDIEs());
202 const auto *CUDie = OrigUnit.getUnitDIE(false);
203 unsigned Lang = CUDie->getAttributeValueAsUnsignedConstant(
204 &OrigUnit, dwarf::DW_AT_language, 0);
205 HasODR = CanUseODR && (Lang == dwarf::DW_LANG_C_plus_plus ||
206 Lang == dwarf::DW_LANG_C_plus_plus_03 ||
207 Lang == dwarf::DW_LANG_C_plus_plus_11 ||
208 Lang == dwarf::DW_LANG_C_plus_plus_14 ||
209 Lang == dwarf::DW_LANG_ObjC_plus_plus);
212 CompileUnit(CompileUnit &&RHS)
213 : OrigUnit(RHS.OrigUnit), Info(std::move(RHS.Info)),
214 CUDie(std::move(RHS.CUDie)), StartOffset(RHS.StartOffset),
215 NextUnitOffset(RHS.NextUnitOffset), RangeAlloc(), Ranges(RangeAlloc) {
216 // The CompileUnit container has been 'reserve()'d with the right
217 // size. We cannot move the IntervalMap anyway.
218 llvm_unreachable("CompileUnits should not be moved.");
221 DWARFUnit &getOrigUnit() const { return OrigUnit; }
223 unsigned getUniqueID() const { return ID; }
225 DIE *getOutputUnitDIE() const { return CUDie; }
226 void setOutputUnitDIE(DIE *Die) { CUDie = Die; }
228 bool hasODR() const { return HasODR; }
229 bool isClangModule() const { return !ClangModuleName.empty(); }
230 const std::string &getClangModuleName() const { return ClangModuleName; }
232 DIEInfo &getInfo(unsigned Idx) { return Info[Idx]; }
233 const DIEInfo &getInfo(unsigned Idx) const { return Info[Idx]; }
235 uint64_t getStartOffset() const { return StartOffset; }
236 uint64_t getNextUnitOffset() const { return NextUnitOffset; }
237 void setStartOffset(uint64_t DebugInfoSize) { StartOffset = DebugInfoSize; }
239 uint64_t getLowPc() const { return LowPc; }
240 uint64_t getHighPc() const { return HighPc; }
242 Optional<PatchLocation> getUnitRangesAttribute() const {
243 return UnitRangeAttribute;
245 const FunctionIntervals &getFunctionRanges() const { return Ranges; }
246 const std::vector<PatchLocation> &getRangesAttributes() const {
247 return RangeAttributes;
250 const std::vector<std::pair<PatchLocation, int64_t>> &
251 getLocationAttributes() const {
252 return LocationAttributes;
255 void setHasInterestingContent() { HasInterestingContent = true; }
256 bool hasInterestingContent() { return HasInterestingContent; }
258 /// Mark every DIE in this unit as kept. This function also
259 /// marks variables as InDebugMap so that they appear in the
260 /// reconstructed accelerator tables.
261 void markEverythingAsKept();
263 /// \brief Compute the end offset for this unit. Must be
264 /// called after the CU's DIEs have been cloned.
265 /// \returns the next unit offset (which is also the current
266 /// debug_info section size).
267 uint64_t computeNextUnitOffset();
269 /// \brief Keep track of a forward reference to DIE \p Die in \p
270 /// RefUnit by \p Attr. The attribute should be fixed up later to
271 /// point to the absolute offset of \p Die in the debug_info section
272 /// or to the canonical offset of \p Ctxt if it is non-null.
273 void noteForwardReference(DIE *Die, const CompileUnit *RefUnit,
274 DeclContext *Ctxt, PatchLocation Attr);
276 /// \brief Apply all fixups recored by noteForwardReference().
277 void fixupForwardReferences();
279 /// \brief Add a function range [\p LowPC, \p HighPC) that is
280 /// relocatad by applying offset \p PCOffset.
281 void addFunctionRange(uint64_t LowPC, uint64_t HighPC, int64_t PCOffset);
283 /// \brief Keep track of a DW_AT_range attribute that we will need to
285 void noteRangeAttribute(const DIE &Die, PatchLocation Attr);
287 /// \brief Keep track of a location attribute pointing to a location
288 /// list in the debug_loc section.
289 void noteLocationAttribute(PatchLocation Attr, int64_t PcOffset);
291 /// \brief Add a name accelerator entry for \p Die with \p Name
292 /// which is stored in the string table at \p Offset.
293 void addNameAccelerator(const DIE *Die, const char *Name, uint32_t Offset,
294 bool SkipPubnamesSection = false);
296 /// \brief Add a type accelerator entry for \p Die with \p Name
297 /// which is stored in the string table at \p Offset.
298 void addTypeAccelerator(const DIE *Die, const char *Name, uint32_t Offset);
301 StringRef Name; ///< Name of the entry.
302 const DIE *Die; ///< DIE this entry describes.
303 uint32_t NameOffset; ///< Offset of Name in the string pool.
304 bool SkipPubSection; ///< Emit this entry only in the apple_* sections.
306 AccelInfo(StringRef Name, const DIE *Die, uint32_t NameOffset,
307 bool SkipPubSection = false)
308 : Name(Name), Die(Die), NameOffset(NameOffset),
309 SkipPubSection(SkipPubSection) {}
312 const std::vector<AccelInfo> &getPubnames() const { return Pubnames; }
313 const std::vector<AccelInfo> &getPubtypes() const { return Pubtypes; }
315 /// Get the full path for file \a FileNum in the line table
316 const char *getResolvedPath(unsigned FileNum) {
317 if (FileNum >= ResolvedPaths.size())
319 return ResolvedPaths[FileNum].size() ? ResolvedPaths[FileNum].c_str()
323 /// Set the fully resolved path for the line-table's file \a FileNum
325 void setResolvedPath(unsigned FileNum, const std::string &Path) {
326 if (ResolvedPaths.size() <= FileNum)
327 ResolvedPaths.resize(FileNum + 1);
328 ResolvedPaths[FileNum] = Path;
334 std::vector<DIEInfo> Info; ///< DIE info indexed by DIE index.
335 DIE *CUDie; ///< Root of the linked DIE tree.
337 uint64_t StartOffset;
338 uint64_t NextUnitOffset;
343 /// \brief A list of attributes to fixup with the absolute offset of
344 /// a DIE in the debug_info section.
346 /// The offsets for the attributes in this array couldn't be set while
347 /// cloning because for cross-cu forward refences the target DIE's
348 /// offset isn't known you emit the reference attribute.
349 std::vector<std::tuple<DIE *, const CompileUnit *, DeclContext *,
350 PatchLocation>> ForwardDIEReferences;
352 FunctionIntervals::Allocator RangeAlloc;
353 /// \brief The ranges in that interval map are the PC ranges for
354 /// functions in this unit, associated with the PC offset to apply
355 /// to the addresses to get the linked address.
356 FunctionIntervals Ranges;
358 /// \brief DW_AT_ranges attributes to patch after we have gathered
359 /// all the unit's function addresses.
361 std::vector<PatchLocation> RangeAttributes;
362 Optional<PatchLocation> UnitRangeAttribute;
365 /// \brief Location attributes that need to be transfered from th
366 /// original debug_loc section to the liked one. They are stored
367 /// along with the PC offset that is to be applied to their
368 /// function's address.
369 std::vector<std::pair<PatchLocation, int64_t>> LocationAttributes;
371 /// \brief Accelerator entries for the unit, both for the pub*
372 /// sections and the apple* ones.
374 std::vector<AccelInfo> Pubnames;
375 std::vector<AccelInfo> Pubtypes;
378 /// Cached resolved paths from the line table.
379 std::vector<std::string> ResolvedPaths;
381 /// Is this unit subject to the ODR rule?
383 /// Did a DIE actually contain a valid reloc?
384 bool HasInterestingContent;
385 /// If this is a Clang module, this holds the module's name.
386 std::string ClangModuleName;
389 void CompileUnit::markEverythingAsKept() {
391 // Mark everything that wasn't explicity marked for pruning.
395 uint64_t CompileUnit::computeNextUnitOffset() {
396 NextUnitOffset = StartOffset + 11 /* Header size */;
397 // The root DIE might be null, meaning that the Unit had nothing to
398 // contribute to the linked output. In that case, we will emit the
399 // unit header without any actual DIE.
401 NextUnitOffset += CUDie->getSize();
402 return NextUnitOffset;
405 /// \brief Keep track of a forward cross-cu reference from this unit
406 /// to \p Die that lives in \p RefUnit.
407 void CompileUnit::noteForwardReference(DIE *Die, const CompileUnit *RefUnit,
408 DeclContext *Ctxt, PatchLocation Attr) {
409 ForwardDIEReferences.emplace_back(Die, RefUnit, Ctxt, Attr);
412 /// \brief Apply all fixups recorded by noteForwardReference().
413 void CompileUnit::fixupForwardReferences() {
414 for (const auto &Ref : ForwardDIEReferences) {
416 const CompileUnit *RefUnit;
419 std::tie(RefDie, RefUnit, Ctxt, Attr) = Ref;
420 if (Ctxt && Ctxt->getCanonicalDIEOffset())
421 Attr.set(Ctxt->getCanonicalDIEOffset());
423 Attr.set(RefDie->getOffset() + RefUnit->getStartOffset());
427 void CompileUnit::addFunctionRange(uint64_t FuncLowPc, uint64_t FuncHighPc,
429 Ranges.insert(FuncLowPc, FuncHighPc, PcOffset);
430 this->LowPc = std::min(LowPc, FuncLowPc + PcOffset);
431 this->HighPc = std::max(HighPc, FuncHighPc + PcOffset);
434 void CompileUnit::noteRangeAttribute(const DIE &Die, PatchLocation Attr) {
435 if (Die.getTag() != dwarf::DW_TAG_compile_unit)
436 RangeAttributes.push_back(Attr);
438 UnitRangeAttribute = Attr;
441 void CompileUnit::noteLocationAttribute(PatchLocation Attr, int64_t PcOffset) {
442 LocationAttributes.emplace_back(Attr, PcOffset);
445 /// \brief Add a name accelerator entry for \p Die with \p Name
446 /// which is stored in the string table at \p Offset.
447 void CompileUnit::addNameAccelerator(const DIE *Die, const char *Name,
448 uint32_t Offset, bool SkipPubSection) {
449 Pubnames.emplace_back(Name, Die, Offset, SkipPubSection);
452 /// \brief Add a type accelerator entry for \p Die with \p Name
453 /// which is stored in the string table at \p Offset.
454 void CompileUnit::addTypeAccelerator(const DIE *Die, const char *Name,
456 Pubtypes.emplace_back(Name, Die, Offset, false);
459 /// \brief The Dwarf streaming logic
461 /// All interactions with the MC layer that is used to build the debug
462 /// information binary representation are handled in this class.
463 class DwarfStreamer {
464 /// \defgroup MCObjects MC layer objects constructed by the streamer
466 std::unique_ptr<MCRegisterInfo> MRI;
467 std::unique_ptr<MCAsmInfo> MAI;
468 std::unique_ptr<MCObjectFileInfo> MOFI;
469 std::unique_ptr<MCContext> MC;
470 MCAsmBackend *MAB; // Owned by MCStreamer
471 std::unique_ptr<MCInstrInfo> MII;
472 std::unique_ptr<MCSubtargetInfo> MSTI;
473 MCCodeEmitter *MCE; // Owned by MCStreamer
474 MCStreamer *MS; // Owned by AsmPrinter
475 std::unique_ptr<TargetMachine> TM;
476 std::unique_ptr<AsmPrinter> Asm;
479 /// \brief the file we stream the linked Dwarf to.
480 std::unique_ptr<raw_fd_ostream> OutFile;
482 uint32_t RangesSectionSize;
483 uint32_t LocSectionSize;
484 uint32_t LineSectionSize;
485 uint32_t FrameSectionSize;
487 /// \brief Emit the pubnames or pubtypes section contribution for \p
488 /// Unit into \p Sec. The data is provided in \p Names.
489 void emitPubSectionForUnit(MCSection *Sec, StringRef Name,
490 const CompileUnit &Unit,
491 const std::vector<CompileUnit::AccelInfo> &Names);
494 /// \brief Actually create the streamer and the ouptut file.
496 /// This could be done directly in the constructor, but it feels
497 /// more natural to handle errors through return value.
498 bool init(Triple TheTriple, StringRef OutputFilename);
500 /// \brief Dump the file to the disk.
501 bool finish(const DebugMap &);
503 AsmPrinter &getAsmPrinter() const { return *Asm; }
505 /// \brief Set the current output section to debug_info and change
506 /// the MC Dwarf version to \p DwarfVersion.
507 void switchToDebugInfoSection(unsigned DwarfVersion);
509 /// \brief Emit the compilation unit header for \p Unit in the
510 /// debug_info section.
512 /// As a side effect, this also switches the current Dwarf version
513 /// of the MC layer to the one of U.getOrigUnit().
514 void emitCompileUnitHeader(CompileUnit &Unit);
516 /// \brief Recursively emit the DIE tree rooted at \p Die.
517 void emitDIE(DIE &Die);
519 /// \brief Emit the abbreviation table \p Abbrevs to the
520 /// debug_abbrev section.
521 void emitAbbrevs(const std::vector<DIEAbbrev *> &Abbrevs);
523 /// \brief Emit the string table described by \p Pool.
524 void emitStrings(const NonRelocatableStringpool &Pool);
526 /// \brief Emit debug_ranges for \p FuncRange by translating the
527 /// original \p Entries.
528 void emitRangesEntries(
529 int64_t UnitPcOffset, uint64_t OrigLowPc,
530 FunctionIntervals::const_iterator FuncRange,
531 const std::vector<DWARFDebugRangeList::RangeListEntry> &Entries,
532 unsigned AddressSize);
534 /// \brief Emit debug_aranges entries for \p Unit and if \p
535 /// DoRangesSection is true, also emit the debug_ranges entries for
536 /// the DW_TAG_compile_unit's DW_AT_ranges attribute.
537 void emitUnitRangesEntries(CompileUnit &Unit, bool DoRangesSection);
539 uint32_t getRangesSectionSize() const { return RangesSectionSize; }
541 /// \brief Emit the debug_loc contribution for \p Unit by copying
542 /// the entries from \p Dwarf and offseting them. Update the
543 /// location attributes to point to the new entries.
544 void emitLocationsForUnit(const CompileUnit &Unit, DWARFContext &Dwarf);
546 /// \brief Emit the line table described in \p Rows into the
547 /// debug_line section.
548 void emitLineTableForUnit(MCDwarfLineTableParams Params,
549 StringRef PrologueBytes, unsigned MinInstLength,
550 std::vector<DWARFDebugLine::Row> &Rows,
551 unsigned AdddressSize);
553 uint32_t getLineSectionSize() const { return LineSectionSize; }
555 /// \brief Emit the .debug_pubnames contribution for \p Unit.
556 void emitPubNamesForUnit(const CompileUnit &Unit);
558 /// \brief Emit the .debug_pubtypes contribution for \p Unit.
559 void emitPubTypesForUnit(const CompileUnit &Unit);
561 /// \brief Emit a CIE.
562 void emitCIE(StringRef CIEBytes);
564 /// \brief Emit an FDE with data \p Bytes.
565 void emitFDE(uint32_t CIEOffset, uint32_t AddreSize, uint32_t Address,
568 uint32_t getFrameSectionSize() const { return FrameSectionSize; }
571 bool DwarfStreamer::init(Triple TheTriple, StringRef OutputFilename) {
572 std::string ErrorStr;
573 std::string TripleName;
574 StringRef Context = "dwarf streamer init";
577 const Target *TheTarget =
578 TargetRegistry::lookupTarget(TripleName, TheTriple, ErrorStr);
580 return error(ErrorStr, Context);
581 TripleName = TheTriple.getTriple();
583 // Create all the MC Objects.
584 MRI.reset(TheTarget->createMCRegInfo(TripleName));
586 return error(Twine("no register info for target ") + TripleName, Context);
588 MAI.reset(TheTarget->createMCAsmInfo(*MRI, TripleName));
590 return error("no asm info for target " + TripleName, Context);
592 MOFI.reset(new MCObjectFileInfo);
593 MC.reset(new MCContext(MAI.get(), MRI.get(), MOFI.get()));
594 MOFI->InitMCObjectFileInfo(TheTriple, Reloc::Default, CodeModel::Default,
597 MAB = TheTarget->createMCAsmBackend(*MRI, TripleName, "");
599 return error("no asm backend for target " + TripleName, Context);
601 MII.reset(TheTarget->createMCInstrInfo());
603 return error("no instr info info for target " + TripleName, Context);
605 MSTI.reset(TheTarget->createMCSubtargetInfo(TripleName, "", ""));
607 return error("no subtarget info for target " + TripleName, Context);
609 MCE = TheTarget->createMCCodeEmitter(*MII, *MRI, *MC);
611 return error("no code emitter for target " + TripleName, Context);
613 // Create the output file.
616 llvm::make_unique<raw_fd_ostream>(OutputFilename, EC, sys::fs::F_None);
618 return error(Twine(OutputFilename) + ": " + EC.message(), Context);
620 MS = TheTarget->createMCObjectStreamer(TheTriple, *MC, *MAB, *OutFile, MCE,
622 /*DWARFMustBeAtTheEnd*/ false);
624 return error("no object streamer for target " + TripleName, Context);
626 // Finally create the AsmPrinter we'll use to emit the DIEs.
627 TM.reset(TheTarget->createTargetMachine(TripleName, "", "", TargetOptions()));
629 return error("no target machine for target " + TripleName, Context);
631 Asm.reset(TheTarget->createAsmPrinter(*TM, std::unique_ptr<MCStreamer>(MS)));
633 return error("no asm printer for target " + TripleName, Context);
635 RangesSectionSize = 0;
638 FrameSectionSize = 0;
643 bool DwarfStreamer::finish(const DebugMap &DM) {
644 if (DM.getTriple().isOSDarwin() && !DM.getBinaryPath().empty())
645 return MachOUtils::generateDsymCompanion(DM, *MS, *OutFile);
651 /// \brief Set the current output section to debug_info and change
652 /// the MC Dwarf version to \p DwarfVersion.
653 void DwarfStreamer::switchToDebugInfoSection(unsigned DwarfVersion) {
654 MS->SwitchSection(MOFI->getDwarfInfoSection());
655 MC->setDwarfVersion(DwarfVersion);
658 /// \brief Emit the compilation unit header for \p Unit in the
659 /// debug_info section.
661 /// A Dwarf scetion header is encoded as:
662 /// uint32_t Unit length (omiting this field)
664 /// uint32_t Abbreviation table offset
665 /// uint8_t Address size
667 /// Leading to a total of 11 bytes.
668 void DwarfStreamer::emitCompileUnitHeader(CompileUnit &Unit) {
669 unsigned Version = Unit.getOrigUnit().getVersion();
670 switchToDebugInfoSection(Version);
672 // Emit size of content not including length itself. The size has
673 // already been computed in CompileUnit::computeOffsets(). Substract
674 // 4 to that size to account for the length field.
675 Asm->EmitInt32(Unit.getNextUnitOffset() - Unit.getStartOffset() - 4);
676 Asm->EmitInt16(Version);
677 // We share one abbreviations table across all units so it's always at the
678 // start of the section.
680 Asm->EmitInt8(Unit.getOrigUnit().getAddressByteSize());
683 /// \brief Emit the \p Abbrevs array as the shared abbreviation table
684 /// for the linked Dwarf file.
685 void DwarfStreamer::emitAbbrevs(const std::vector<DIEAbbrev *> &Abbrevs) {
686 MS->SwitchSection(MOFI->getDwarfAbbrevSection());
687 Asm->emitDwarfAbbrevs(Abbrevs);
690 /// \brief Recursively emit the DIE tree rooted at \p Die.
691 void DwarfStreamer::emitDIE(DIE &Die) {
692 MS->SwitchSection(MOFI->getDwarfInfoSection());
693 Asm->emitDwarfDIE(Die);
696 /// \brief Emit the debug_str section stored in \p Pool.
697 void DwarfStreamer::emitStrings(const NonRelocatableStringpool &Pool) {
698 Asm->OutStreamer->SwitchSection(MOFI->getDwarfStrSection());
699 for (auto *Entry = Pool.getFirstEntry(); Entry;
700 Entry = Pool.getNextEntry(Entry))
701 Asm->OutStreamer->EmitBytes(
702 StringRef(Entry->getKey().data(), Entry->getKey().size() + 1));
705 /// \brief Emit the debug_range section contents for \p FuncRange by
706 /// translating the original \p Entries. The debug_range section
707 /// format is totally trivial, consisting just of pairs of address
708 /// sized addresses describing the ranges.
709 void DwarfStreamer::emitRangesEntries(
710 int64_t UnitPcOffset, uint64_t OrigLowPc,
711 FunctionIntervals::const_iterator FuncRange,
712 const std::vector<DWARFDebugRangeList::RangeListEntry> &Entries,
713 unsigned AddressSize) {
714 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfRangesSection());
716 // Offset each range by the right amount.
717 int64_t PcOffset = Entries.empty() ? 0 : FuncRange.value() + UnitPcOffset;
718 for (const auto &Range : Entries) {
719 if (Range.isBaseAddressSelectionEntry(AddressSize)) {
720 warn("unsupported base address selection operation",
721 "emitting debug_ranges");
724 // Do not emit empty ranges.
725 if (Range.StartAddress == Range.EndAddress)
728 // All range entries should lie in the function range.
729 if (!(Range.StartAddress + OrigLowPc >= FuncRange.start() &&
730 Range.EndAddress + OrigLowPc <= FuncRange.stop()))
731 warn("inconsistent range data.", "emitting debug_ranges");
732 MS->EmitIntValue(Range.StartAddress + PcOffset, AddressSize);
733 MS->EmitIntValue(Range.EndAddress + PcOffset, AddressSize);
734 RangesSectionSize += 2 * AddressSize;
737 // Add the terminator entry.
738 MS->EmitIntValue(0, AddressSize);
739 MS->EmitIntValue(0, AddressSize);
740 RangesSectionSize += 2 * AddressSize;
743 /// \brief Emit the debug_aranges contribution of a unit and
744 /// if \p DoDebugRanges is true the debug_range contents for a
745 /// compile_unit level DW_AT_ranges attribute (Which are basically the
746 /// same thing with a different base address).
747 /// Just aggregate all the ranges gathered inside that unit.
748 void DwarfStreamer::emitUnitRangesEntries(CompileUnit &Unit,
749 bool DoDebugRanges) {
750 unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
751 // Gather the ranges in a vector, so that we can simplify them. The
752 // IntervalMap will have coalesced the non-linked ranges, but here
753 // we want to coalesce the linked addresses.
754 std::vector<std::pair<uint64_t, uint64_t>> Ranges;
755 const auto &FunctionRanges = Unit.getFunctionRanges();
756 for (auto Range = FunctionRanges.begin(), End = FunctionRanges.end();
757 Range != End; ++Range)
758 Ranges.push_back(std::make_pair(Range.start() + Range.value(),
759 Range.stop() + Range.value()));
761 // The object addresses where sorted, but again, the linked
762 // addresses might end up in a different order.
763 std::sort(Ranges.begin(), Ranges.end());
765 if (!Ranges.empty()) {
766 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfARangesSection());
768 MCSymbol *BeginLabel = Asm->createTempSymbol("Barange");
769 MCSymbol *EndLabel = Asm->createTempSymbol("Earange");
771 unsigned HeaderSize =
772 sizeof(int32_t) + // Size of contents (w/o this field
773 sizeof(int16_t) + // DWARF ARange version number
774 sizeof(int32_t) + // Offset of CU in the .debug_info section
775 sizeof(int8_t) + // Pointer Size (in bytes)
776 sizeof(int8_t); // Segment Size (in bytes)
778 unsigned TupleSize = AddressSize * 2;
779 unsigned Padding = OffsetToAlignment(HeaderSize, TupleSize);
781 Asm->EmitLabelDifference(EndLabel, BeginLabel, 4); // Arange length
782 Asm->OutStreamer->EmitLabel(BeginLabel);
783 Asm->EmitInt16(dwarf::DW_ARANGES_VERSION); // Version number
784 Asm->EmitInt32(Unit.getStartOffset()); // Corresponding unit's offset
785 Asm->EmitInt8(AddressSize); // Address size
786 Asm->EmitInt8(0); // Segment size
788 Asm->OutStreamer->EmitFill(Padding, 0x0);
790 for (auto Range = Ranges.begin(), End = Ranges.end(); Range != End;
792 uint64_t RangeStart = Range->first;
793 MS->EmitIntValue(RangeStart, AddressSize);
794 while ((Range + 1) != End && Range->second == (Range + 1)->first)
796 MS->EmitIntValue(Range->second - RangeStart, AddressSize);
800 Asm->OutStreamer->EmitIntValue(0, AddressSize);
801 Asm->OutStreamer->EmitIntValue(0, AddressSize);
802 Asm->OutStreamer->EmitLabel(EndLabel);
808 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfRangesSection());
809 // Offset each range by the right amount.
810 int64_t PcOffset = -Unit.getLowPc();
811 // Emit coalesced ranges.
812 for (auto Range = Ranges.begin(), End = Ranges.end(); Range != End; ++Range) {
813 MS->EmitIntValue(Range->first + PcOffset, AddressSize);
814 while (Range + 1 != End && Range->second == (Range + 1)->first)
816 MS->EmitIntValue(Range->second + PcOffset, AddressSize);
817 RangesSectionSize += 2 * AddressSize;
820 // Add the terminator entry.
821 MS->EmitIntValue(0, AddressSize);
822 MS->EmitIntValue(0, AddressSize);
823 RangesSectionSize += 2 * AddressSize;
826 /// \brief Emit location lists for \p Unit and update attribtues to
827 /// point to the new entries.
828 void DwarfStreamer::emitLocationsForUnit(const CompileUnit &Unit,
829 DWARFContext &Dwarf) {
830 const auto &Attributes = Unit.getLocationAttributes();
832 if (Attributes.empty())
835 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLocSection());
837 unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
838 const DWARFSection &InputSec = Dwarf.getLocSection();
839 DataExtractor Data(InputSec.Data, Dwarf.isLittleEndian(), AddressSize);
840 DWARFUnit &OrigUnit = Unit.getOrigUnit();
841 const auto *OrigUnitDie = OrigUnit.getUnitDIE(false);
842 int64_t UnitPcOffset = 0;
843 uint64_t OrigLowPc = OrigUnitDie->getAttributeValueAsAddress(
844 &OrigUnit, dwarf::DW_AT_low_pc, -1ULL);
845 if (OrigLowPc != -1ULL)
846 UnitPcOffset = int64_t(OrigLowPc) - Unit.getLowPc();
848 for (const auto &Attr : Attributes) {
849 uint32_t Offset = Attr.first.get();
850 Attr.first.set(LocSectionSize);
851 // This is the quantity to add to the old location address to get
852 // the correct address for the new one.
853 int64_t LocPcOffset = Attr.second + UnitPcOffset;
854 while (Data.isValidOffset(Offset)) {
855 uint64_t Low = Data.getUnsigned(&Offset, AddressSize);
856 uint64_t High = Data.getUnsigned(&Offset, AddressSize);
857 LocSectionSize += 2 * AddressSize;
858 if (Low == 0 && High == 0) {
859 Asm->OutStreamer->EmitIntValue(0, AddressSize);
860 Asm->OutStreamer->EmitIntValue(0, AddressSize);
863 Asm->OutStreamer->EmitIntValue(Low + LocPcOffset, AddressSize);
864 Asm->OutStreamer->EmitIntValue(High + LocPcOffset, AddressSize);
865 uint64_t Length = Data.getU16(&Offset);
866 Asm->OutStreamer->EmitIntValue(Length, 2);
867 // Just copy the bytes over.
868 Asm->OutStreamer->EmitBytes(
869 StringRef(InputSec.Data.substr(Offset, Length)));
871 LocSectionSize += Length + 2;
876 void DwarfStreamer::emitLineTableForUnit(MCDwarfLineTableParams Params,
877 StringRef PrologueBytes,
878 unsigned MinInstLength,
879 std::vector<DWARFDebugLine::Row> &Rows,
880 unsigned PointerSize) {
881 // Switch to the section where the table will be emitted into.
882 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLineSection());
883 MCSymbol *LineStartSym = MC->createTempSymbol();
884 MCSymbol *LineEndSym = MC->createTempSymbol();
886 // The first 4 bytes is the total length of the information for this
887 // compilation unit (not including these 4 bytes for the length).
888 Asm->EmitLabelDifference(LineEndSym, LineStartSym, 4);
889 Asm->OutStreamer->EmitLabel(LineStartSym);
891 MS->EmitBytes(PrologueBytes);
892 LineSectionSize += PrologueBytes.size() + 4;
894 SmallString<128> EncodingBuffer;
895 raw_svector_ostream EncodingOS(EncodingBuffer);
898 // We only have the dummy entry, dsymutil emits an entry with a 0
899 // address in that case.
900 MCDwarfLineAddr::Encode(*MC, Params, INT64_MAX, 0, EncodingOS);
901 MS->EmitBytes(EncodingOS.str());
902 LineSectionSize += EncodingBuffer.size();
903 MS->EmitLabel(LineEndSym);
907 // Line table state machine fields
908 unsigned FileNum = 1;
909 unsigned LastLine = 1;
911 unsigned IsStatement = 1;
913 uint64_t Address = -1ULL;
915 unsigned RowsSinceLastSequence = 0;
917 for (unsigned Idx = 0; Idx < Rows.size(); ++Idx) {
918 auto &Row = Rows[Idx];
920 int64_t AddressDelta;
921 if (Address == -1ULL) {
922 MS->EmitIntValue(dwarf::DW_LNS_extended_op, 1);
923 MS->EmitULEB128IntValue(PointerSize + 1);
924 MS->EmitIntValue(dwarf::DW_LNE_set_address, 1);
925 MS->EmitIntValue(Row.Address, PointerSize);
926 LineSectionSize += 2 + PointerSize + getULEB128Size(PointerSize + 1);
929 AddressDelta = (Row.Address - Address) / MinInstLength;
932 // FIXME: code copied and transfromed from
933 // MCDwarf.cpp::EmitDwarfLineTable. We should find a way to share
934 // this code, but the current compatibility requirement with
935 // classic dsymutil makes it hard. Revisit that once this
936 // requirement is dropped.
938 if (FileNum != Row.File) {
940 MS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
941 MS->EmitULEB128IntValue(FileNum);
942 LineSectionSize += 1 + getULEB128Size(FileNum);
944 if (Column != Row.Column) {
946 MS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
947 MS->EmitULEB128IntValue(Column);
948 LineSectionSize += 1 + getULEB128Size(Column);
951 // FIXME: We should handle the discriminator here, but dsymutil
952 // doesn' consider it, thus ignore it for now.
954 if (Isa != Row.Isa) {
956 MS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
957 MS->EmitULEB128IntValue(Isa);
958 LineSectionSize += 1 + getULEB128Size(Isa);
960 if (IsStatement != Row.IsStmt) {
961 IsStatement = Row.IsStmt;
962 MS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
963 LineSectionSize += 1;
965 if (Row.BasicBlock) {
966 MS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1);
967 LineSectionSize += 1;
970 if (Row.PrologueEnd) {
971 MS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
972 LineSectionSize += 1;
975 if (Row.EpilogueBegin) {
976 MS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);
977 LineSectionSize += 1;
980 int64_t LineDelta = int64_t(Row.Line) - LastLine;
981 if (!Row.EndSequence) {
982 MCDwarfLineAddr::Encode(*MC, Params, LineDelta, AddressDelta, EncodingOS);
983 MS->EmitBytes(EncodingOS.str());
984 LineSectionSize += EncodingBuffer.size();
985 EncodingBuffer.resize(0);
986 Address = Row.Address;
988 RowsSinceLastSequence++;
991 MS->EmitIntValue(dwarf::DW_LNS_advance_line, 1);
992 MS->EmitSLEB128IntValue(LineDelta);
993 LineSectionSize += 1 + getSLEB128Size(LineDelta);
996 MS->EmitIntValue(dwarf::DW_LNS_advance_pc, 1);
997 MS->EmitULEB128IntValue(AddressDelta);
998 LineSectionSize += 1 + getULEB128Size(AddressDelta);
1000 MCDwarfLineAddr::Encode(*MC, Params, INT64_MAX, 0, EncodingOS);
1001 MS->EmitBytes(EncodingOS.str());
1002 LineSectionSize += EncodingBuffer.size();
1003 EncodingBuffer.resize(0);
1005 LastLine = FileNum = IsStatement = 1;
1006 RowsSinceLastSequence = Column = Isa = 0;
1010 if (RowsSinceLastSequence) {
1011 MCDwarfLineAddr::Encode(*MC, Params, INT64_MAX, 0, EncodingOS);
1012 MS->EmitBytes(EncodingOS.str());
1013 LineSectionSize += EncodingBuffer.size();
1014 EncodingBuffer.resize(0);
1017 MS->EmitLabel(LineEndSym);
1020 /// \brief Emit the pubnames or pubtypes section contribution for \p
1021 /// Unit into \p Sec. The data is provided in \p Names.
1022 void DwarfStreamer::emitPubSectionForUnit(
1023 MCSection *Sec, StringRef SecName, const CompileUnit &Unit,
1024 const std::vector<CompileUnit::AccelInfo> &Names) {
1028 // Start the dwarf pubnames section.
1029 Asm->OutStreamer->SwitchSection(Sec);
1030 MCSymbol *BeginLabel = Asm->createTempSymbol("pub" + SecName + "_begin");
1031 MCSymbol *EndLabel = Asm->createTempSymbol("pub" + SecName + "_end");
1033 bool HeaderEmitted = false;
1034 // Emit the pubnames for this compilation unit.
1035 for (const auto &Name : Names) {
1036 if (Name.SkipPubSection)
1039 if (!HeaderEmitted) {
1041 Asm->EmitLabelDifference(EndLabel, BeginLabel, 4); // Length
1042 Asm->OutStreamer->EmitLabel(BeginLabel);
1043 Asm->EmitInt16(dwarf::DW_PUBNAMES_VERSION); // Version
1044 Asm->EmitInt32(Unit.getStartOffset()); // Unit offset
1045 Asm->EmitInt32(Unit.getNextUnitOffset() - Unit.getStartOffset()); // Size
1046 HeaderEmitted = true;
1048 Asm->EmitInt32(Name.Die->getOffset());
1049 Asm->OutStreamer->EmitBytes(
1050 StringRef(Name.Name.data(), Name.Name.size() + 1));
1055 Asm->EmitInt32(0); // End marker.
1056 Asm->OutStreamer->EmitLabel(EndLabel);
1059 /// \brief Emit .debug_pubnames for \p Unit.
1060 void DwarfStreamer::emitPubNamesForUnit(const CompileUnit &Unit) {
1061 emitPubSectionForUnit(MC->getObjectFileInfo()->getDwarfPubNamesSection(),
1062 "names", Unit, Unit.getPubnames());
1065 /// \brief Emit .debug_pubtypes for \p Unit.
1066 void DwarfStreamer::emitPubTypesForUnit(const CompileUnit &Unit) {
1067 emitPubSectionForUnit(MC->getObjectFileInfo()->getDwarfPubTypesSection(),
1068 "types", Unit, Unit.getPubtypes());
1071 /// \brief Emit a CIE into the debug_frame section.
1072 void DwarfStreamer::emitCIE(StringRef CIEBytes) {
1073 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfFrameSection());
1075 MS->EmitBytes(CIEBytes);
1076 FrameSectionSize += CIEBytes.size();
1079 /// \brief Emit a FDE into the debug_frame section. \p FDEBytes
1080 /// contains the FDE data without the length, CIE offset and address
1081 /// which will be replaced with the paramter values.
1082 void DwarfStreamer::emitFDE(uint32_t CIEOffset, uint32_t AddrSize,
1083 uint32_t Address, StringRef FDEBytes) {
1084 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfFrameSection());
1086 MS->EmitIntValue(FDEBytes.size() + 4 + AddrSize, 4);
1087 MS->EmitIntValue(CIEOffset, 4);
1088 MS->EmitIntValue(Address, AddrSize);
1089 MS->EmitBytes(FDEBytes);
1090 FrameSectionSize += FDEBytes.size() + 8 + AddrSize;
1093 /// \brief The core of the Dwarf linking logic.
1095 /// The link of the dwarf information from the object files will be
1096 /// driven by the selection of 'root DIEs', which are DIEs that
1097 /// describe variables or functions that are present in the linked
1098 /// binary (and thus have entries in the debug map). All the debug
1099 /// information that will be linked (the DIEs, but also the line
1100 /// tables, ranges, ...) is derived from that set of root DIEs.
1102 /// The root DIEs are identified because they contain relocations that
1103 /// correspond to a debug map entry at specific places (the low_pc for
1104 /// a function, the location for a variable). These relocations are
1105 /// called ValidRelocs in the DwarfLinker and are gathered as a very
1106 /// first step when we start processing a DebugMapObject.
1109 DwarfLinker(StringRef OutputFilename, const LinkOptions &Options)
1110 : OutputFilename(OutputFilename), Options(Options),
1111 BinHolder(Options.Verbose), LastCIEOffset(0) {}
1114 for (auto *Abbrev : Abbreviations)
1118 /// \brief Link the contents of the DebugMap.
1119 bool link(const DebugMap &);
1121 void reportWarning(const Twine &Warning, const DWARFUnit *Unit = nullptr,
1122 const DWARFDebugInfoEntryMinimal *DIE = nullptr) const;
1125 /// \brief Called at the start of a debug object link.
1126 void startDebugObject(DWARFContext &, DebugMapObject &);
1128 /// \brief Called at the end of a debug object link.
1129 void endDebugObject();
1131 /// Keeps track of relocations.
1132 class RelocationManager {
1137 const DebugMapObject::DebugMapEntry *Mapping;
1139 ValidReloc(uint32_t Offset, uint32_t Size, uint64_t Addend,
1140 const DebugMapObject::DebugMapEntry *Mapping)
1141 : Offset(Offset), Size(Size), Addend(Addend), Mapping(Mapping) {}
1143 bool operator<(const ValidReloc &RHS) const {
1144 return Offset < RHS.Offset;
1148 DwarfLinker &Linker;
1150 /// \brief The valid relocations for the current DebugMapObject.
1151 /// This vector is sorted by relocation offset.
1152 std::vector<ValidReloc> ValidRelocs;
1154 /// \brief Index into ValidRelocs of the next relocation to
1155 /// consider. As we walk the DIEs in acsending file offset and as
1156 /// ValidRelocs is sorted by file offset, keeping this index
1157 /// uptodate is all we have to do to have a cheap lookup during the
1158 /// root DIE selection and during DIE cloning.
1159 unsigned NextValidReloc;
1162 RelocationManager(DwarfLinker &Linker)
1163 : Linker(Linker), NextValidReloc(0) {}
1165 bool hasValidRelocs() const { return !ValidRelocs.empty(); }
1166 /// \brief Reset the NextValidReloc counter.
1167 void resetValidRelocs() { NextValidReloc = 0; }
1169 /// \defgroup FindValidRelocations Translate debug map into a list
1170 /// of relevant relocations
1173 bool findValidRelocsInDebugInfo(const object::ObjectFile &Obj,
1174 const DebugMapObject &DMO);
1176 bool findValidRelocs(const object::SectionRef &Section,
1177 const object::ObjectFile &Obj,
1178 const DebugMapObject &DMO);
1180 void findValidRelocsMachO(const object::SectionRef &Section,
1181 const object::MachOObjectFile &Obj,
1182 const DebugMapObject &DMO);
1185 bool hasValidRelocation(uint32_t StartOffset, uint32_t EndOffset,
1186 CompileUnit::DIEInfo &Info);
1188 bool applyValidRelocs(MutableArrayRef<char> Data, uint32_t BaseOffset,
1189 bool isLittleEndian);
1192 /// \defgroup FindRootDIEs Find DIEs corresponding to debug map entries.
1195 /// \brief Recursively walk the \p DIE tree and look for DIEs to
1196 /// keep. Store that information in \p CU's DIEInfo.
1197 void lookForDIEsToKeep(RelocationManager &RelocMgr,
1198 const DWARFDebugInfoEntryMinimal &DIE,
1199 const DebugMapObject &DMO, CompileUnit &CU,
1202 /// If this compile unit is really a skeleton CU that points to a
1203 /// clang module, register it in ClangModules and return true.
1205 /// A skeleton CU is a CU without children, a DW_AT_gnu_dwo_name
1206 /// pointing to the module, and a DW_AT_gnu_dwo_id with the module
1208 bool registerModuleReference(const DWARFDebugInfoEntryMinimal &CUDie,
1209 const DWARFUnit &Unit, DebugMap &ModuleMap,
1210 unsigned Indent = 0);
1212 /// Recursively add the debug info in this clang module .pcm
1213 /// file (and all the modules imported by it in a bottom-up fashion)
1215 void loadClangModule(StringRef Filename, StringRef ModulePath,
1216 StringRef ModuleName, uint64_t DwoId,
1217 DebugMap &ModuleMap, unsigned Indent = 0);
1219 /// \brief Flags passed to DwarfLinker::lookForDIEsToKeep
1220 enum TravesalFlags {
1221 TF_Keep = 1 << 0, ///< Mark the traversed DIEs as kept.
1222 TF_InFunctionScope = 1 << 1, ///< Current scope is a fucntion scope.
1223 TF_DependencyWalk = 1 << 2, ///< Walking the dependencies of a kept DIE.
1224 TF_ParentWalk = 1 << 3, ///< Walking up the parents of a kept DIE.
1225 TF_ODR = 1 << 4, ///< Use the ODR whhile keeping dependants.
1226 TF_SkipPC = 1 << 5, ///< Skip all location attributes.
1229 /// \brief Mark the passed DIE as well as all the ones it depends on
1231 void keepDIEAndDependencies(RelocationManager &RelocMgr,
1232 const DWARFDebugInfoEntryMinimal &DIE,
1233 CompileUnit::DIEInfo &MyInfo,
1234 const DebugMapObject &DMO, CompileUnit &CU,
1237 unsigned shouldKeepDIE(RelocationManager &RelocMgr,
1238 const DWARFDebugInfoEntryMinimal &DIE,
1239 CompileUnit &Unit, CompileUnit::DIEInfo &MyInfo,
1242 unsigned shouldKeepVariableDIE(RelocationManager &RelocMgr,
1243 const DWARFDebugInfoEntryMinimal &DIE,
1245 CompileUnit::DIEInfo &MyInfo, unsigned Flags);
1247 unsigned shouldKeepSubprogramDIE(RelocationManager &RelocMgr,
1248 const DWARFDebugInfoEntryMinimal &DIE,
1250 CompileUnit::DIEInfo &MyInfo,
1253 bool hasValidRelocation(uint32_t StartOffset, uint32_t EndOffset,
1254 CompileUnit::DIEInfo &Info);
1257 /// \defgroup Linking Methods used to link the debug information
1262 DwarfLinker &Linker;
1263 RelocationManager &RelocMgr;
1264 /// Allocator used for all the DIEValue objects.
1265 BumpPtrAllocator &DIEAlloc;
1266 MutableArrayRef<CompileUnit> CompileUnits;
1267 LinkOptions Options;
1270 DIECloner(DwarfLinker &Linker, RelocationManager &RelocMgr,
1271 BumpPtrAllocator &DIEAlloc,
1272 MutableArrayRef<CompileUnit> CompileUnits, LinkOptions &Options)
1273 : Linker(Linker), RelocMgr(RelocMgr), DIEAlloc(DIEAlloc),
1274 CompileUnits(CompileUnits), Options(Options) {}
1276 /// Recursively clone \p InputDIE into an tree of DIE objects
1277 /// where useless (as decided by lookForDIEsToKeep()) bits have been
1278 /// stripped out and addresses have been rewritten according to the
1281 /// \param OutOffset is the offset the cloned DIE in the output
1283 /// \param PCOffset (while cloning a function scope) is the offset
1284 /// applied to the entry point of the function to get the linked address.
1286 /// \returns the root of the cloned tree or null if nothing was selected.
1287 DIE *cloneDIE(const DWARFDebugInfoEntryMinimal &InputDIE, CompileUnit &U,
1288 int64_t PCOffset, uint32_t OutOffset, unsigned Flags);
1290 /// Construct the output DIE tree by cloning the DIEs we
1291 /// chose to keep above. If there are no valid relocs, then there's
1292 /// nothing to clone/emit.
1293 void cloneAllCompileUnits(DWARFContextInMemory &DwarfContext);
1296 typedef DWARFAbbreviationDeclaration::AttributeSpec AttributeSpec;
1298 /// Information gathered and exchanged between the various
1299 /// clone*Attributes helpers about the attributes of a particular DIE.
1300 struct AttributesInfo {
1301 const char *Name, *MangledName; ///< Names.
1302 uint32_t NameOffset, MangledNameOffset; ///< Offsets in the string pool.
1304 uint64_t OrigLowPc; ///< Value of AT_low_pc in the input DIE
1305 uint64_t OrigHighPc; ///< Value of AT_high_pc in the input DIE
1306 int64_t PCOffset; ///< Offset to apply to PC addresses inside a function.
1308 bool HasLowPc; ///< Does the DIE have a low_pc attribute?
1309 bool IsDeclaration; ///< Is this DIE only a declaration?
1312 : Name(nullptr), MangledName(nullptr), NameOffset(0),
1313 MangledNameOffset(0), OrigLowPc(UINT64_MAX), OrigHighPc(0),
1314 PCOffset(0), HasLowPc(false), IsDeclaration(false) {}
1317 /// Helper for cloneDIE.
1318 unsigned cloneAttribute(DIE &Die,
1319 const DWARFDebugInfoEntryMinimal &InputDIE,
1320 CompileUnit &U, const DWARFFormValue &Val,
1321 const AttributeSpec AttrSpec, unsigned AttrSize,
1322 AttributesInfo &AttrInfo);
1324 /// Clone a string attribute described by \p AttrSpec and add
1326 /// \returns the size of the new attribute.
1327 unsigned cloneStringAttribute(DIE &Die, AttributeSpec AttrSpec,
1328 const DWARFFormValue &Val,
1329 const DWARFUnit &U);
1331 /// Clone an attribute referencing another DIE and add
1333 /// \returns the size of the new attribute.
1335 cloneDieReferenceAttribute(DIE &Die,
1336 const DWARFDebugInfoEntryMinimal &InputDIE,
1337 AttributeSpec AttrSpec, unsigned AttrSize,
1338 const DWARFFormValue &Val, CompileUnit &Unit);
1340 /// Clone an attribute referencing another DIE and add
1342 /// \returns the size of the new attribute.
1343 unsigned cloneBlockAttribute(DIE &Die, AttributeSpec AttrSpec,
1344 const DWARFFormValue &Val, unsigned AttrSize);
1346 /// Clone an attribute referencing another DIE and add
1348 /// \returns the size of the new attribute.
1349 unsigned cloneAddressAttribute(DIE &Die, AttributeSpec AttrSpec,
1350 const DWARFFormValue &Val,
1351 const CompileUnit &Unit,
1352 AttributesInfo &Info);
1354 /// Clone a scalar attribute and add it to \p Die.
1355 /// \returns the size of the new attribute.
1356 unsigned cloneScalarAttribute(DIE &Die,
1357 const DWARFDebugInfoEntryMinimal &InputDIE,
1358 CompileUnit &U, AttributeSpec AttrSpec,
1359 const DWARFFormValue &Val, unsigned AttrSize,
1360 AttributesInfo &Info);
1362 /// Get the potential name and mangled name for the entity
1363 /// described by \p Die and store them in \Info if they are not
1365 /// \returns is a name was found.
1366 bool getDIENames(const DWARFDebugInfoEntryMinimal &Die, DWARFUnit &U,
1367 AttributesInfo &Info);
1369 /// Create a copy of abbreviation Abbrev.
1370 void copyAbbrev(const DWARFAbbreviationDeclaration &Abbrev, bool hasODR);
1373 /// \brief Assign an abbreviation number to \p Abbrev
1374 void AssignAbbrev(DIEAbbrev &Abbrev);
1376 /// \brief FoldingSet that uniques the abbreviations.
1377 FoldingSet<DIEAbbrev> AbbreviationsSet;
1378 /// \brief Storage for the unique Abbreviations.
1379 /// This is passed to AsmPrinter::emitDwarfAbbrevs(), thus it cannot
1380 /// be changed to a vecot of unique_ptrs.
1381 std::vector<DIEAbbrev *> Abbreviations;
1383 /// \brief Compute and emit debug_ranges section for \p Unit, and
1384 /// patch the attributes referencing it.
1385 void patchRangesForUnit(const CompileUnit &Unit, DWARFContext &Dwarf) const;
1387 /// \brief Generate and emit the DW_AT_ranges attribute for a
1388 /// compile_unit if it had one.
1389 void generateUnitRanges(CompileUnit &Unit) const;
1391 /// \brief Extract the line tables fromt he original dwarf, extract
1392 /// the relevant parts according to the linked function ranges and
1393 /// emit the result in the debug_line section.
1394 void patchLineTableForUnit(CompileUnit &Unit, DWARFContext &OrigDwarf);
1396 /// \brief Emit the accelerator entries for \p Unit.
1397 void emitAcceleratorEntriesForUnit(CompileUnit &Unit);
1399 /// \brief Patch the frame info for an object file and emit it.
1400 void patchFrameInfoForObject(const DebugMapObject &, DWARFContext &,
1401 unsigned AddressSize);
1403 /// \brief DIELoc objects that need to be destructed (but not freed!).
1404 std::vector<DIELoc *> DIELocs;
1405 /// \brief DIEBlock objects that need to be destructed (but not freed!).
1406 std::vector<DIEBlock *> DIEBlocks;
1407 /// \brief Allocator used for all the DIEValue objects.
1408 BumpPtrAllocator DIEAlloc;
1411 /// ODR Contexts for that link.
1412 DeclContextTree ODRContexts;
1414 /// \defgroup Helpers Various helper methods.
1417 bool createStreamer(Triple TheTriple, StringRef OutputFilename);
1419 /// \brief Attempt to load a debug object from disk.
1420 ErrorOr<const object::ObjectFile &> loadObject(BinaryHolder &BinaryHolder,
1421 DebugMapObject &Obj,
1422 const DebugMap &Map);
1425 std::string OutputFilename;
1426 LinkOptions Options;
1427 BinaryHolder BinHolder;
1428 std::unique_ptr<DwarfStreamer> Streamer;
1429 uint64_t OutputDebugInfoSize;
1430 unsigned UnitID; ///< A unique ID that identifies each compile unit.
1432 /// The units of the current debug map object.
1433 std::vector<CompileUnit> Units;
1435 /// The debug map object curently under consideration.
1436 DebugMapObject *CurrentDebugObject;
1438 /// \brief The Dwarf string pool
1439 NonRelocatableStringpool StringPool;
1441 /// \brief This map is keyed by the entry PC of functions in that
1442 /// debug object and the associated value is a pair storing the
1443 /// corresponding end PC and the offset to apply to get the linked
1446 /// See startDebugObject() for a more complete description of its use.
1447 std::map<uint64_t, std::pair<uint64_t, int64_t>> Ranges;
1449 /// \brief The CIEs that have been emitted in the output
1450 /// section. The actual CIE data serves a the key to this StringMap,
1451 /// this takes care of comparing the semantics of CIEs defined in
1452 /// different object files.
1453 StringMap<uint32_t> EmittedCIEs;
1455 /// Offset of the last CIE that has been emitted in the output
1456 /// debug_frame section.
1457 uint32_t LastCIEOffset;
1459 /// Mapping the PCM filename to the DwoId.
1460 StringMap<uint64_t> ClangModules;
1463 /// Similar to DWARFUnitSection::getUnitForOffset(), but returning our
1464 /// CompileUnit object instead.
1465 static CompileUnit *getUnitForOffset(MutableArrayRef<CompileUnit> Units,
1468 std::upper_bound(Units.begin(), Units.end(), Offset,
1469 [](uint32_t LHS, const CompileUnit &RHS) {
1470 return LHS < RHS.getOrigUnit().getNextUnitOffset();
1472 return CU != Units.end() ? &*CU : nullptr;
1475 /// Resolve the DIE attribute reference that has been
1476 /// extracted in \p RefValue. The resulting DIE migh be in another
1477 /// CompileUnit which is stored into \p ReferencedCU.
1478 /// \returns null if resolving fails for any reason.
1479 static const DWARFDebugInfoEntryMinimal *resolveDIEReference(
1480 const DwarfLinker &Linker, MutableArrayRef<CompileUnit> Units,
1481 const DWARFFormValue &RefValue, const DWARFUnit &Unit,
1482 const DWARFDebugInfoEntryMinimal &DIE, CompileUnit *&RefCU) {
1483 assert(RefValue.isFormClass(DWARFFormValue::FC_Reference));
1484 uint64_t RefOffset = *RefValue.getAsReference(&Unit);
1486 if ((RefCU = getUnitForOffset(Units, RefOffset)))
1487 if (const auto *RefDie = RefCU->getOrigUnit().getDIEForOffset(RefOffset))
1490 Linker.reportWarning("could not find referenced DIE", &Unit, &DIE);
1494 /// \returns whether the passed \a Attr type might contain a DIE
1495 /// reference suitable for ODR uniquing.
1496 static bool isODRAttribute(uint16_t Attr) {
1500 case dwarf::DW_AT_type:
1501 case dwarf::DW_AT_containing_type:
1502 case dwarf::DW_AT_specification:
1503 case dwarf::DW_AT_abstract_origin:
1504 case dwarf::DW_AT_import:
1507 llvm_unreachable("Improper attribute.");
1510 /// Set the last DIE/CU a context was seen in and, possibly invalidate
1511 /// the context if it is ambiguous.
1513 /// In the current implementation, we don't handle overloaded
1514 /// functions well, because the argument types are not taken into
1515 /// account when computing the DeclContext tree.
1517 /// Some of this is mitigated byt using mangled names that do contain
1518 /// the arguments types, but sometimes (eg. with function templates)
1519 /// we don't have that. In that case, just do not unique anything that
1520 /// refers to the contexts we are not able to distinguish.
1522 /// If a context that is not a namespace appears twice in the same CU,
1523 /// we know it is ambiguous. Make it invalid.
1524 bool DeclContext::setLastSeenDIE(CompileUnit &U,
1525 const DWARFDebugInfoEntryMinimal *Die) {
1526 if (LastSeenCompileUnitID == U.getUniqueID()) {
1527 DWARFUnit &OrigUnit = U.getOrigUnit();
1528 uint32_t FirstIdx = OrigUnit.getDIEIndex(LastSeenDIE);
1529 U.getInfo(FirstIdx).Ctxt = nullptr;
1533 LastSeenCompileUnitID = U.getUniqueID();
1538 /// Get the child context of \a Context corresponding to \a DIE.
1540 /// \returns the child context or null if we shouldn't track children
1541 /// contexts. It also returns an additional bit meaning 'invalid'. An
1542 /// invalid context means it shouldn't be considered for uniquing, but
1543 /// its not returning null, because some children of that context
1544 /// might be uniquing candidates.
1545 /// FIXME: this is for dsymutil-classic compatibility, I don't think
1546 /// it buys us much.
1547 PointerIntPair<DeclContext *, 1> DeclContextTree::getChildDeclContext(
1548 DeclContext &Context, const DWARFDebugInfoEntryMinimal *DIE, CompileUnit &U,
1549 NonRelocatableStringpool &StringPool) {
1550 unsigned Tag = DIE->getTag();
1552 // FIXME: dsymutil-classic compat: We should bail out here if we
1553 // have a specification or an abstract_origin. We will get the
1554 // parent context wrong here.
1558 // By default stop gathering child contexts.
1559 return PointerIntPair<DeclContext *, 1>(nullptr);
1560 case dwarf::DW_TAG_module:
1562 case dwarf::DW_TAG_compile_unit:
1563 return PointerIntPair<DeclContext *, 1>(&Context);
1564 case dwarf::DW_TAG_subprogram:
1565 // Do not unique anything inside CU local functions.
1566 if ((Context.getTag() == dwarf::DW_TAG_namespace ||
1567 Context.getTag() == dwarf::DW_TAG_compile_unit) &&
1568 !DIE->getAttributeValueAsUnsignedConstant(&U.getOrigUnit(),
1569 dwarf::DW_AT_external, 0))
1570 return PointerIntPair<DeclContext *, 1>(nullptr);
1572 case dwarf::DW_TAG_member:
1573 case dwarf::DW_TAG_namespace:
1574 case dwarf::DW_TAG_structure_type:
1575 case dwarf::DW_TAG_class_type:
1576 case dwarf::DW_TAG_union_type:
1577 case dwarf::DW_TAG_enumeration_type:
1578 case dwarf::DW_TAG_typedef:
1579 // Artificial things might be ambiguous, because they might be
1580 // created on demand. For example implicitely defined constructors
1581 // are ambiguous because of the way we identify contexts, and they
1582 // won't be generated everytime everywhere.
1583 if (DIE->getAttributeValueAsUnsignedConstant(&U.getOrigUnit(),
1584 dwarf::DW_AT_artificial, 0))
1585 return PointerIntPair<DeclContext *, 1>(nullptr);
1589 const char *Name = DIE->getName(&U.getOrigUnit(), DINameKind::LinkageName);
1590 const char *ShortName = DIE->getName(&U.getOrigUnit(), DINameKind::ShortName);
1592 StringRef ShortNameRef;
1596 NameRef = StringPool.internString(Name);
1597 else if (Tag == dwarf::DW_TAG_namespace)
1598 // FIXME: For dsymutil-classic compatibility. I think uniquing
1599 // within anonymous namespaces is wrong. There is no ODR guarantee
1601 NameRef = StringPool.internString("(anonymous namespace)");
1603 if (ShortName && ShortName != Name)
1604 ShortNameRef = StringPool.internString(ShortName);
1606 ShortNameRef = NameRef;
1608 if (Tag != dwarf::DW_TAG_class_type && Tag != dwarf::DW_TAG_structure_type &&
1609 Tag != dwarf::DW_TAG_union_type &&
1610 Tag != dwarf::DW_TAG_enumeration_type && NameRef.empty())
1611 return PointerIntPair<DeclContext *, 1>(nullptr);
1615 unsigned ByteSize = 0;
1617 // Gather some discriminating data about the DeclContext we will be
1618 // creating: File, line number and byte size. This shouldn't be
1619 // necessary, because the ODR is just about names, but given that we
1620 // do some approximations with overloaded functions and anonymous
1621 // namespaces, use these additional data points to make the process
1622 // safer. This is disabled for clang modules, because forward
1623 // declarations of module-defined types do not have a file and line.
1624 ByteSize = DIE->getAttributeValueAsUnsignedConstant(
1625 &U.getOrigUnit(), dwarf::DW_AT_byte_size, UINT64_MAX);
1626 if (!U.isClangModule() && (Tag != dwarf::DW_TAG_namespace || !Name)) {
1627 if (unsigned FileNum = DIE->getAttributeValueAsUnsignedConstant(
1628 &U.getOrigUnit(), dwarf::DW_AT_decl_file, 0)) {
1629 if (const auto *LT = U.getOrigUnit().getContext().getLineTableForUnit(
1630 &U.getOrigUnit())) {
1631 // FIXME: dsymutil-classic compatibility. I'd rather not
1632 // unique anything in anonymous namespaces, but if we do, then
1633 // verify that the file and line correspond.
1634 if (!Name && Tag == dwarf::DW_TAG_namespace)
1637 // FIXME: Passing U.getOrigUnit().getCompilationDir()
1638 // instead of "" would allow more uniquing, but for now, do
1639 // it this way to match dsymutil-classic.
1640 if (LT->getFileNameByIndex(
1642 DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath,
1644 Line = DIE->getAttributeValueAsUnsignedConstant(
1645 &U.getOrigUnit(), dwarf::DW_AT_decl_line, 0);
1646 #ifdef HAVE_REALPATH
1647 // Cache the resolved paths, because calling realpath is expansive.
1648 if (const char *ResolvedPath = U.getResolvedPath(FileNum)) {
1649 File = ResolvedPath;
1651 char RealPath[PATH_MAX + 1];
1652 RealPath[PATH_MAX] = 0;
1653 if (::realpath(File.c_str(), RealPath))
1655 U.setResolvedPath(FileNum, File);
1658 FileRef = StringPool.internString(File);
1664 if (!Line && NameRef.empty())
1665 return PointerIntPair<DeclContext *, 1>(nullptr);
1667 // We hash NameRef, which is the mangled name, in order to get most
1668 // overloaded functions resolve correctly.
1670 // Strictly speaking, hashing the Tag is only necessary for a
1671 // DW_TAG_module, to prevent uniquing of a module and a namespace
1672 // with the same name.
1674 // FIXME: dsymutil-classic won't unique the same type presented
1675 // once as a struct and once as a class. Using the Tag in the fully
1676 // qualified name hash to get the same effect.
1677 unsigned Hash = hash_combine(Context.getQualifiedNameHash(), Tag, NameRef);
1679 // FIXME: dsymutil-classic compatibility: when we don't have a name,
1680 // use the filename.
1681 if (Tag == dwarf::DW_TAG_namespace && NameRef == "(anonymous namespace)")
1682 Hash = hash_combine(Hash, FileRef);
1684 // Now look if this context already exists.
1685 DeclContext Key(Hash, Line, ByteSize, Tag, NameRef, FileRef, Context);
1686 auto ContextIter = Contexts.find(&Key);
1688 if (ContextIter == Contexts.end()) {
1689 // The context wasn't found.
1691 DeclContext *NewContext =
1692 new (Allocator) DeclContext(Hash, Line, ByteSize, Tag, NameRef, FileRef,
1693 Context, DIE, U.getUniqueID());
1694 std::tie(ContextIter, Inserted) = Contexts.insert(NewContext);
1695 assert(Inserted && "Failed to insert DeclContext");
1697 } else if (Tag != dwarf::DW_TAG_namespace &&
1698 !(*ContextIter)->setLastSeenDIE(U, DIE)) {
1699 // The context was found, but it is ambiguous with another context
1700 // in the same file. Mark it invalid.
1701 return PointerIntPair<DeclContext *, 1>(*ContextIter, /* Invalid= */ 1);
1704 assert(ContextIter != Contexts.end());
1705 // FIXME: dsymutil-classic compatibility. Union types aren't
1706 // uniques, but their children might be.
1707 if ((Tag == dwarf::DW_TAG_subprogram &&
1708 Context.getTag() != dwarf::DW_TAG_structure_type &&
1709 Context.getTag() != dwarf::DW_TAG_class_type) ||
1710 (Tag == dwarf::DW_TAG_union_type))
1711 return PointerIntPair<DeclContext *, 1>(*ContextIter, /* Invalid= */ 1);
1713 return PointerIntPair<DeclContext *, 1>(*ContextIter);
1716 bool DwarfLinker::DIECloner::getDIENames(const DWARFDebugInfoEntryMinimal &Die,
1717 DWARFUnit &U, AttributesInfo &Info) {
1718 // FIXME: a bit wasteful as the first getName might return the
1720 if (!Info.MangledName &&
1721 (Info.MangledName = Die.getName(&U, DINameKind::LinkageName)))
1722 Info.MangledNameOffset =
1723 Linker.StringPool.getStringOffset(Info.MangledName);
1725 if (!Info.Name && (Info.Name = Die.getName(&U, DINameKind::ShortName)))
1726 Info.NameOffset = Linker.StringPool.getStringOffset(Info.Name);
1728 return Info.Name || Info.MangledName;
1731 /// \brief Report a warning to the user, optionaly including
1732 /// information about a specific \p DIE related to the warning.
1733 void DwarfLinker::reportWarning(const Twine &Warning, const DWARFUnit *Unit,
1734 const DWARFDebugInfoEntryMinimal *DIE) const {
1735 StringRef Context = "<debug map>";
1736 if (CurrentDebugObject)
1737 Context = CurrentDebugObject->getObjectFilename();
1738 warn(Warning, Context);
1740 if (!Options.Verbose || !DIE)
1743 errs() << " in DIE:\n";
1744 DIE->dump(errs(), const_cast<DWARFUnit *>(Unit), 0 /* RecurseDepth */,
1748 bool DwarfLinker::createStreamer(Triple TheTriple, StringRef OutputFilename) {
1749 if (Options.NoOutput)
1752 Streamer = llvm::make_unique<DwarfStreamer>();
1753 return Streamer->init(TheTriple, OutputFilename);
1756 /// Recursive helper to build the global DeclContext information and
1757 /// gather the child->parent relationships in the original compile unit.
1759 /// \return true when this DIE and all of its children are only
1760 /// forward declarations to types defined in external clang modules
1761 /// (i.e., forward declarations that are children of a DW_TAG_module).
1762 static bool analyzeContextInfo(const DWARFDebugInfoEntryMinimal *DIE,
1763 unsigned ParentIdx, CompileUnit &CU,
1764 DeclContext *CurrentDeclContext,
1765 NonRelocatableStringpool &StringPool,
1766 DeclContextTree &Contexts,
1767 bool InImportedModule = false) {
1768 unsigned MyIdx = CU.getOrigUnit().getDIEIndex(DIE);
1769 CompileUnit::DIEInfo &Info = CU.getInfo(MyIdx);
1771 // Clang imposes an ODR on modules(!) regardless of the language:
1772 // "The module-id should consist of only a single identifier,
1773 // which provides the name of the module being defined. Each
1774 // module shall have a single definition."
1776 // This does not extend to the types inside the modules:
1777 // "[I]n C, this implies that if two structs are defined in
1778 // different submodules with the same name, those two types are
1779 // distinct types (but may be compatible types if their
1780 // definitions match)."
1782 // We treat non-C++ modules like namespaces for this reason.
1783 if (DIE->getTag() == dwarf::DW_TAG_module && ParentIdx == 0 &&
1784 DIE->getAttributeValueAsString(&CU.getOrigUnit(), dwarf::DW_AT_name,
1785 "") != CU.getClangModuleName()) {
1786 InImportedModule = true;
1789 Info.ParentIdx = ParentIdx;
1790 if (CU.hasODR() || CU.isClangModule() || InImportedModule) {
1791 if (CurrentDeclContext) {
1792 auto PtrInvalidPair = Contexts.getChildDeclContext(*CurrentDeclContext,
1793 DIE, CU, StringPool);
1794 CurrentDeclContext = PtrInvalidPair.getPointer();
1796 PtrInvalidPair.getInt() ? nullptr : PtrInvalidPair.getPointer();
1798 Info.Ctxt = CurrentDeclContext = nullptr;
1801 Info.Prune = InImportedModule;
1802 if (DIE->hasChildren())
1803 for (auto *Child = DIE->getFirstChild(); Child && !Child->isNULL();
1804 Child = Child->getSibling())
1805 Info.Prune &= analyzeContextInfo(Child, MyIdx, CU, CurrentDeclContext,
1806 StringPool, Contexts, InImportedModule);
1808 // Prune this DIE if it is either a forward declaration inside a
1809 // DW_TAG_module or a DW_TAG_module that contains nothing but
1810 // forward declarations.
1811 Info.Prune &= (DIE->getTag() == dwarf::DW_TAG_module) ||
1812 DIE->getAttributeValueAsUnsignedConstant(
1813 &CU.getOrigUnit(), dwarf::DW_AT_declaration, 0);
1818 static bool dieNeedsChildrenToBeMeaningful(uint32_t Tag) {
1822 case dwarf::DW_TAG_subprogram:
1823 case dwarf::DW_TAG_lexical_block:
1824 case dwarf::DW_TAG_subroutine_type:
1825 case dwarf::DW_TAG_structure_type:
1826 case dwarf::DW_TAG_class_type:
1827 case dwarf::DW_TAG_union_type:
1830 llvm_unreachable("Invalid Tag");
1833 static unsigned getRefAddrSize(const DWARFUnit &U) {
1834 if (U.getVersion() == 2)
1835 return U.getAddressByteSize();
1839 void DwarfLinker::startDebugObject(DWARFContext &Dwarf, DebugMapObject &Obj) {
1840 Units.reserve(Dwarf.getNumCompileUnits());
1841 // Iterate over the debug map entries and put all the ones that are
1842 // functions (because they have a size) into the Ranges map. This
1843 // map is very similar to the FunctionRanges that are stored in each
1844 // unit, with 2 notable differences:
1845 // - obviously this one is global, while the other ones are per-unit.
1846 // - this one contains not only the functions described in the DIE
1847 // tree, but also the ones that are only in the debug map.
1848 // The latter information is required to reproduce dsymutil's logic
1849 // while linking line tables. The cases where this information
1850 // matters look like bugs that need to be investigated, but for now
1851 // we need to reproduce dsymutil's behavior.
1852 // FIXME: Once we understood exactly if that information is needed,
1853 // maybe totally remove this (or try to use it to do a real
1854 // -gline-tables-only on Darwin.
1855 for (const auto &Entry : Obj.symbols()) {
1856 const auto &Mapping = Entry.getValue();
1858 Ranges[Mapping.ObjectAddress] = std::make_pair(
1859 Mapping.ObjectAddress + Mapping.Size,
1860 int64_t(Mapping.BinaryAddress) - Mapping.ObjectAddress);
1864 void DwarfLinker::endDebugObject() {
1868 for (auto I = DIEBlocks.begin(), E = DIEBlocks.end(); I != E; ++I)
1870 for (auto I = DIELocs.begin(), E = DIELocs.end(); I != E; ++I)
1878 /// \brief Iterate over the relocations of the given \p Section and
1879 /// store the ones that correspond to debug map entries into the
1880 /// ValidRelocs array.
1881 void DwarfLinker::RelocationManager::
1882 findValidRelocsMachO(const object::SectionRef &Section,
1883 const object::MachOObjectFile &Obj,
1884 const DebugMapObject &DMO) {
1886 Section.getContents(Contents);
1887 DataExtractor Data(Contents, Obj.isLittleEndian(), 0);
1889 for (const object::RelocationRef &Reloc : Section.relocations()) {
1890 object::DataRefImpl RelocDataRef = Reloc.getRawDataRefImpl();
1891 MachO::any_relocation_info MachOReloc = Obj.getRelocation(RelocDataRef);
1892 unsigned RelocSize = 1 << Obj.getAnyRelocationLength(MachOReloc);
1893 uint64_t Offset64 = Reloc.getOffset();
1894 if ((RelocSize != 4 && RelocSize != 8)) {
1895 Linker.reportWarning(" unsupported relocation in debug_info section.");
1898 uint32_t Offset = Offset64;
1899 // Mach-o uses REL relocations, the addend is at the relocation offset.
1900 uint64_t Addend = Data.getUnsigned(&Offset, RelocSize);
1902 auto Sym = Reloc.getSymbol();
1903 if (Sym != Obj.symbol_end()) {
1904 ErrorOr<StringRef> SymbolName = Sym->getName();
1906 Linker.reportWarning("error getting relocation symbol name.");
1909 if (const auto *Mapping = DMO.lookupSymbol(*SymbolName))
1910 ValidRelocs.emplace_back(Offset64, RelocSize, Addend, Mapping);
1911 } else if (const auto *Mapping = DMO.lookupObjectAddress(Addend)) {
1912 // Do not store the addend. The addend was the address of the
1913 // symbol in the object file, the address in the binary that is
1914 // stored in the debug map doesn't need to be offseted.
1915 ValidRelocs.emplace_back(Offset64, RelocSize, 0, Mapping);
1920 /// \brief Dispatch the valid relocation finding logic to the
1921 /// appropriate handler depending on the object file format.
1922 bool DwarfLinker::RelocationManager::findValidRelocs(
1923 const object::SectionRef &Section, const object::ObjectFile &Obj,
1924 const DebugMapObject &DMO) {
1925 // Dispatch to the right handler depending on the file type.
1926 if (auto *MachOObj = dyn_cast<object::MachOObjectFile>(&Obj))
1927 findValidRelocsMachO(Section, *MachOObj, DMO);
1929 Linker.reportWarning(Twine("unsupported object file type: ") +
1932 if (ValidRelocs.empty())
1935 // Sort the relocations by offset. We will walk the DIEs linearly in
1936 // the file, this allows us to just keep an index in the relocation
1937 // array that we advance during our walk, rather than resorting to
1938 // some associative container. See DwarfLinker::NextValidReloc.
1939 std::sort(ValidRelocs.begin(), ValidRelocs.end());
1943 /// \brief Look for relocations in the debug_info section that match
1944 /// entries in the debug map. These relocations will drive the Dwarf
1945 /// link by indicating which DIEs refer to symbols present in the
1947 /// \returns wether there are any valid relocations in the debug info.
1948 bool DwarfLinker::RelocationManager::
1949 findValidRelocsInDebugInfo(const object::ObjectFile &Obj,
1950 const DebugMapObject &DMO) {
1951 // Find the debug_info section.
1952 for (const object::SectionRef &Section : Obj.sections()) {
1953 StringRef SectionName;
1954 Section.getName(SectionName);
1955 SectionName = SectionName.substr(SectionName.find_first_not_of("._"));
1956 if (SectionName != "debug_info")
1958 return findValidRelocs(Section, Obj, DMO);
1963 /// \brief Checks that there is a relocation against an actual debug
1964 /// map entry between \p StartOffset and \p NextOffset.
1966 /// This function must be called with offsets in strictly ascending
1967 /// order because it never looks back at relocations it already 'went past'.
1968 /// \returns true and sets Info.InDebugMap if it is the case.
1969 bool DwarfLinker::RelocationManager::
1970 hasValidRelocation(uint32_t StartOffset, uint32_t EndOffset,
1971 CompileUnit::DIEInfo &Info) {
1972 assert(NextValidReloc == 0 ||
1973 StartOffset > ValidRelocs[NextValidReloc - 1].Offset);
1974 if (NextValidReloc >= ValidRelocs.size())
1977 uint64_t RelocOffset = ValidRelocs[NextValidReloc].Offset;
1979 // We might need to skip some relocs that we didn't consider. For
1980 // example the high_pc of a discarded DIE might contain a reloc that
1981 // is in the list because it actually corresponds to the start of a
1982 // function that is in the debug map.
1983 while (RelocOffset < StartOffset && NextValidReloc < ValidRelocs.size() - 1)
1984 RelocOffset = ValidRelocs[++NextValidReloc].Offset;
1986 if (RelocOffset < StartOffset || RelocOffset >= EndOffset)
1989 const auto &ValidReloc = ValidRelocs[NextValidReloc++];
1990 const auto &Mapping = ValidReloc.Mapping->getValue();
1991 if (Linker.Options.Verbose)
1992 outs() << "Found valid debug map entry: " << ValidReloc.Mapping->getKey()
1993 << " " << format("\t%016" PRIx64 " => %016" PRIx64,
1994 uint64_t(Mapping.ObjectAddress),
1995 uint64_t(Mapping.BinaryAddress));
1997 Info.AddrAdjust = int64_t(Mapping.BinaryAddress) + ValidReloc.Addend -
1998 Mapping.ObjectAddress;
1999 Info.InDebugMap = true;
2003 /// \brief Get the starting and ending (exclusive) offset for the
2004 /// attribute with index \p Idx descibed by \p Abbrev. \p Offset is
2005 /// supposed to point to the position of the first attribute described
2007 /// \return [StartOffset, EndOffset) as a pair.
2008 static std::pair<uint32_t, uint32_t>
2009 getAttributeOffsets(const DWARFAbbreviationDeclaration *Abbrev, unsigned Idx,
2010 unsigned Offset, const DWARFUnit &Unit) {
2011 DataExtractor Data = Unit.getDebugInfoExtractor();
2013 for (unsigned i = 0; i < Idx; ++i)
2014 DWARFFormValue::skipValue(Abbrev->getFormByIndex(i), Data, &Offset, &Unit);
2016 uint32_t End = Offset;
2017 DWARFFormValue::skipValue(Abbrev->getFormByIndex(Idx), Data, &End, &Unit);
2019 return std::make_pair(Offset, End);
2022 /// \brief Check if a variable describing DIE should be kept.
2023 /// \returns updated TraversalFlags.
2024 unsigned DwarfLinker::shouldKeepVariableDIE(RelocationManager &RelocMgr,
2025 const DWARFDebugInfoEntryMinimal &DIE,
2027 CompileUnit::DIEInfo &MyInfo,
2029 const auto *Abbrev = DIE.getAbbreviationDeclarationPtr();
2031 // Global variables with constant value can always be kept.
2032 if (!(Flags & TF_InFunctionScope) &&
2033 Abbrev->findAttributeIndex(dwarf::DW_AT_const_value) != -1U) {
2034 MyInfo.InDebugMap = true;
2035 return Flags | TF_Keep;
2038 uint32_t LocationIdx = Abbrev->findAttributeIndex(dwarf::DW_AT_location);
2039 if (LocationIdx == -1U)
2042 uint32_t Offset = DIE.getOffset() + getULEB128Size(Abbrev->getCode());
2043 const DWARFUnit &OrigUnit = Unit.getOrigUnit();
2044 uint32_t LocationOffset, LocationEndOffset;
2045 std::tie(LocationOffset, LocationEndOffset) =
2046 getAttributeOffsets(Abbrev, LocationIdx, Offset, OrigUnit);
2048 // See if there is a relocation to a valid debug map entry inside
2049 // this variable's location. The order is important here. We want to
2050 // always check in the variable has a valid relocation, so that the
2051 // DIEInfo is filled. However, we don't want a static variable in a
2052 // function to force us to keep the enclosing function.
2053 if (!RelocMgr.hasValidRelocation(LocationOffset, LocationEndOffset, MyInfo) ||
2054 (Flags & TF_InFunctionScope))
2057 if (Options.Verbose)
2058 DIE.dump(outs(), const_cast<DWARFUnit *>(&OrigUnit), 0, 8 /* Indent */);
2060 return Flags | TF_Keep;
2063 /// \brief Check if a function describing DIE should be kept.
2064 /// \returns updated TraversalFlags.
2065 unsigned DwarfLinker::shouldKeepSubprogramDIE(
2066 RelocationManager &RelocMgr,
2067 const DWARFDebugInfoEntryMinimal &DIE, CompileUnit &Unit,
2068 CompileUnit::DIEInfo &MyInfo, unsigned Flags) {
2069 const auto *Abbrev = DIE.getAbbreviationDeclarationPtr();
2071 Flags |= TF_InFunctionScope;
2073 uint32_t LowPcIdx = Abbrev->findAttributeIndex(dwarf::DW_AT_low_pc);
2074 if (LowPcIdx == -1U)
2077 uint32_t Offset = DIE.getOffset() + getULEB128Size(Abbrev->getCode());
2078 const DWARFUnit &OrigUnit = Unit.getOrigUnit();
2079 uint32_t LowPcOffset, LowPcEndOffset;
2080 std::tie(LowPcOffset, LowPcEndOffset) =
2081 getAttributeOffsets(Abbrev, LowPcIdx, Offset, OrigUnit);
2084 DIE.getAttributeValueAsAddress(&OrigUnit, dwarf::DW_AT_low_pc, -1ULL);
2085 assert(LowPc != -1ULL && "low_pc attribute is not an address.");
2086 if (LowPc == -1ULL ||
2087 !RelocMgr.hasValidRelocation(LowPcOffset, LowPcEndOffset, MyInfo))
2090 if (Options.Verbose)
2091 DIE.dump(outs(), const_cast<DWARFUnit *>(&OrigUnit), 0, 8 /* Indent */);
2095 DWARFFormValue HighPcValue;
2096 if (!DIE.getAttributeValue(&OrigUnit, dwarf::DW_AT_high_pc, HighPcValue)) {
2097 reportWarning("Function without high_pc. Range will be discarded.\n",
2103 if (HighPcValue.isFormClass(DWARFFormValue::FC_Address)) {
2104 HighPc = *HighPcValue.getAsAddress(&OrigUnit);
2106 assert(HighPcValue.isFormClass(DWARFFormValue::FC_Constant));
2107 HighPc = LowPc + *HighPcValue.getAsUnsignedConstant();
2110 // Replace the debug map range with a more accurate one.
2111 Ranges[LowPc] = std::make_pair(HighPc, MyInfo.AddrAdjust);
2112 Unit.addFunctionRange(LowPc, HighPc, MyInfo.AddrAdjust);
2116 /// \brief Check if a DIE should be kept.
2117 /// \returns updated TraversalFlags.
2118 unsigned DwarfLinker::shouldKeepDIE(RelocationManager &RelocMgr,
2119 const DWARFDebugInfoEntryMinimal &DIE,
2121 CompileUnit::DIEInfo &MyInfo,
2123 switch (DIE.getTag()) {
2124 case dwarf::DW_TAG_constant:
2125 case dwarf::DW_TAG_variable:
2126 return shouldKeepVariableDIE(RelocMgr, DIE, Unit, MyInfo, Flags);
2127 case dwarf::DW_TAG_subprogram:
2128 return shouldKeepSubprogramDIE(RelocMgr, DIE, Unit, MyInfo, Flags);
2129 case dwarf::DW_TAG_module:
2130 case dwarf::DW_TAG_imported_module:
2131 case dwarf::DW_TAG_imported_declaration:
2132 case dwarf::DW_TAG_imported_unit:
2133 // We always want to keep these.
2134 return Flags | TF_Keep;
2140 /// \brief Mark the passed DIE as well as all the ones it depends on
2143 /// This function is called by lookForDIEsToKeep on DIEs that are
2144 /// newly discovered to be needed in the link. It recursively calls
2145 /// back to lookForDIEsToKeep while adding TF_DependencyWalk to the
2146 /// TraversalFlags to inform it that it's not doing the primary DIE
2148 void DwarfLinker::keepDIEAndDependencies(RelocationManager &RelocMgr,
2149 const DWARFDebugInfoEntryMinimal &Die,
2150 CompileUnit::DIEInfo &MyInfo,
2151 const DebugMapObject &DMO,
2152 CompileUnit &CU, bool UseODR) {
2153 const DWARFUnit &Unit = CU.getOrigUnit();
2156 // First mark all the parent chain as kept.
2157 unsigned AncestorIdx = MyInfo.ParentIdx;
2158 while (!CU.getInfo(AncestorIdx).Keep) {
2159 unsigned ODRFlag = UseODR ? TF_ODR : 0;
2160 lookForDIEsToKeep(RelocMgr, *Unit.getDIEAtIndex(AncestorIdx), DMO, CU,
2161 TF_ParentWalk | TF_Keep | TF_DependencyWalk | ODRFlag);
2162 AncestorIdx = CU.getInfo(AncestorIdx).ParentIdx;
2165 // Then we need to mark all the DIEs referenced by this DIE's
2166 // attributes as kept.
2167 DataExtractor Data = Unit.getDebugInfoExtractor();
2168 const auto *Abbrev = Die.getAbbreviationDeclarationPtr();
2169 uint32_t Offset = Die.getOffset() + getULEB128Size(Abbrev->getCode());
2171 // Mark all DIEs referenced through atttributes as kept.
2172 for (const auto &AttrSpec : Abbrev->attributes()) {
2173 DWARFFormValue Val(AttrSpec.Form);
2175 if (!Val.isFormClass(DWARFFormValue::FC_Reference)) {
2176 DWARFFormValue::skipValue(AttrSpec.Form, Data, &Offset, &Unit);
2180 Val.extractValue(Data, &Offset, &Unit);
2181 CompileUnit *ReferencedCU;
2182 if (const auto *RefDIE =
2183 resolveDIEReference(*this, MutableArrayRef<CompileUnit>(Units), Val,
2184 Unit, Die, ReferencedCU)) {
2185 uint32_t RefIdx = ReferencedCU->getOrigUnit().getDIEIndex(RefDIE);
2186 CompileUnit::DIEInfo &Info = ReferencedCU->getInfo(RefIdx);
2187 // If the referenced DIE has a DeclContext that has already been
2188 // emitted, then do not keep the one in this CU. We'll link to
2189 // the canonical DIE in cloneDieReferenceAttribute.
2190 // FIXME: compatibility with dsymutil-classic. UseODR shouldn't
2191 // be necessary and could be advantageously replaced by
2192 // ReferencedCU->hasODR() && CU.hasODR().
2193 // FIXME: compatibility with dsymutil-classic. There is no
2194 // reason not to unique ref_addr references.
2195 if (AttrSpec.Form != dwarf::DW_FORM_ref_addr && UseODR && Info.Ctxt &&
2196 Info.Ctxt != ReferencedCU->getInfo(Info.ParentIdx).Ctxt &&
2197 Info.Ctxt->getCanonicalDIEOffset() && isODRAttribute(AttrSpec.Attr))
2201 unsigned ODRFlag = UseODR ? TF_ODR : 0;
2202 lookForDIEsToKeep(RelocMgr, *RefDIE, DMO, *ReferencedCU,
2203 TF_Keep | TF_DependencyWalk | ODRFlag);
2208 /// \brief Recursively walk the \p DIE tree and look for DIEs to
2209 /// keep. Store that information in \p CU's DIEInfo.
2211 /// This function is the entry point of the DIE selection
2212 /// algorithm. It is expected to walk the DIE tree in file order and
2213 /// (though the mediation of its helper) call hasValidRelocation() on
2214 /// each DIE that might be a 'root DIE' (See DwarfLinker class
2216 /// While walking the dependencies of root DIEs, this function is
2217 /// also called, but during these dependency walks the file order is
2218 /// not respected. The TF_DependencyWalk flag tells us which kind of
2219 /// traversal we are currently doing.
2220 void DwarfLinker::lookForDIEsToKeep(RelocationManager &RelocMgr,
2221 const DWARFDebugInfoEntryMinimal &Die,
2222 const DebugMapObject &DMO, CompileUnit &CU,
2224 unsigned Idx = CU.getOrigUnit().getDIEIndex(&Die);
2225 CompileUnit::DIEInfo &MyInfo = CU.getInfo(Idx);
2226 bool AlreadyKept = MyInfo.Keep;
2230 // If the Keep flag is set, we are marking a required DIE's
2231 // dependencies. If our target is already marked as kept, we're all
2233 if ((Flags & TF_DependencyWalk) && AlreadyKept)
2236 // We must not call shouldKeepDIE while called from keepDIEAndDependencies,
2237 // because it would screw up the relocation finding logic.
2238 if (!(Flags & TF_DependencyWalk))
2239 Flags = shouldKeepDIE(RelocMgr, Die, CU, MyInfo, Flags);
2241 // If it is a newly kept DIE mark it as well as all its dependencies as kept.
2242 if (!AlreadyKept && (Flags & TF_Keep)) {
2243 bool UseOdr = (Flags & TF_DependencyWalk) ? (Flags & TF_ODR) : CU.hasODR();
2244 keepDIEAndDependencies(RelocMgr, Die, MyInfo, DMO, CU, UseOdr);
2246 // The TF_ParentWalk flag tells us that we are currently walking up
2247 // the parent chain of a required DIE, and we don't want to mark all
2248 // the children of the parents as kept (consider for example a
2249 // DW_TAG_namespace node in the parent chain). There are however a
2250 // set of DIE types for which we want to ignore that directive and still
2251 // walk their children.
2252 if (dieNeedsChildrenToBeMeaningful(Die.getTag()))
2253 Flags &= ~TF_ParentWalk;
2255 if (!Die.hasChildren() || (Flags & TF_ParentWalk))
2258 for (auto *Child = Die.getFirstChild(); Child && !Child->isNULL();
2259 Child = Child->getSibling())
2260 lookForDIEsToKeep(RelocMgr, *Child, DMO, CU, Flags);
2263 /// \brief Assign an abbreviation numer to \p Abbrev.
2265 /// Our DIEs get freed after every DebugMapObject has been processed,
2266 /// thus the FoldingSet we use to unique DIEAbbrevs cannot refer to
2267 /// the instances hold by the DIEs. When we encounter an abbreviation
2268 /// that we don't know, we create a permanent copy of it.
2269 void DwarfLinker::AssignAbbrev(DIEAbbrev &Abbrev) {
2270 // Check the set for priors.
2271 FoldingSetNodeID ID;
2274 DIEAbbrev *InSet = AbbreviationsSet.FindNodeOrInsertPos(ID, InsertToken);
2276 // If it's newly added.
2278 // Assign existing abbreviation number.
2279 Abbrev.setNumber(InSet->getNumber());
2281 // Add to abbreviation list.
2282 Abbreviations.push_back(
2283 new DIEAbbrev(Abbrev.getTag(), Abbrev.hasChildren()));
2284 for (const auto &Attr : Abbrev.getData())
2285 Abbreviations.back()->AddAttribute(Attr.getAttribute(), Attr.getForm());
2286 AbbreviationsSet.InsertNode(Abbreviations.back(), InsertToken);
2287 // Assign the unique abbreviation number.
2288 Abbrev.setNumber(Abbreviations.size());
2289 Abbreviations.back()->setNumber(Abbreviations.size());
2293 unsigned DwarfLinker::DIECloner::cloneStringAttribute(DIE &Die,
2294 AttributeSpec AttrSpec,
2295 const DWARFFormValue &Val,
2296 const DWARFUnit &U) {
2297 // Switch everything to out of line strings.
2298 const char *String = *Val.getAsCString(&U);
2299 unsigned Offset = Linker.StringPool.getStringOffset(String);
2300 Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr), dwarf::DW_FORM_strp,
2301 DIEInteger(Offset));
2305 unsigned DwarfLinker::DIECloner::cloneDieReferenceAttribute(
2306 DIE &Die, const DWARFDebugInfoEntryMinimal &InputDIE,
2307 AttributeSpec AttrSpec, unsigned AttrSize, const DWARFFormValue &Val,
2308 CompileUnit &Unit) {
2309 const DWARFUnit &U = Unit.getOrigUnit();
2310 uint32_t Ref = *Val.getAsReference(&U);
2311 DIE *NewRefDie = nullptr;
2312 CompileUnit *RefUnit = nullptr;
2313 DeclContext *Ctxt = nullptr;
2315 const DWARFDebugInfoEntryMinimal *RefDie =
2316 resolveDIEReference(Linker, CompileUnits, Val, U, InputDIE, RefUnit);
2318 // If the referenced DIE is not found, drop the attribute.
2322 unsigned Idx = RefUnit->getOrigUnit().getDIEIndex(RefDie);
2323 CompileUnit::DIEInfo &RefInfo = RefUnit->getInfo(Idx);
2325 // If we already have emitted an equivalent DeclContext, just point
2327 if (isODRAttribute(AttrSpec.Attr)) {
2328 Ctxt = RefInfo.Ctxt;
2329 if (Ctxt && Ctxt->getCanonicalDIEOffset()) {
2330 DIEInteger Attr(Ctxt->getCanonicalDIEOffset());
2331 Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
2332 dwarf::DW_FORM_ref_addr, Attr);
2333 return getRefAddrSize(U);
2337 if (!RefInfo.Clone) {
2338 assert(Ref > InputDIE.getOffset());
2339 // We haven't cloned this DIE yet. Just create an empty one and
2340 // store it. It'll get really cloned when we process it.
2341 RefInfo.Clone = DIE::get(DIEAlloc, dwarf::Tag(RefDie->getTag()));
2343 NewRefDie = RefInfo.Clone;
2345 if (AttrSpec.Form == dwarf::DW_FORM_ref_addr ||
2346 (Unit.hasODR() && isODRAttribute(AttrSpec.Attr))) {
2347 // We cannot currently rely on a DIEEntry to emit ref_addr
2348 // references, because the implementation calls back to DwarfDebug
2349 // to find the unit offset. (We don't have a DwarfDebug)
2350 // FIXME: we should be able to design DIEEntry reliance on
2353 if (Ref < InputDIE.getOffset()) {
2354 // We must have already cloned that DIE.
2355 uint32_t NewRefOffset =
2356 RefUnit->getStartOffset() + NewRefDie->getOffset();
2357 Attr = NewRefOffset;
2358 Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
2359 dwarf::DW_FORM_ref_addr, DIEInteger(Attr));
2361 // A forward reference. Note and fixup later.
2363 Unit.noteForwardReference(
2364 NewRefDie, RefUnit, Ctxt,
2365 Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
2366 dwarf::DW_FORM_ref_addr, DIEInteger(Attr)));
2368 return getRefAddrSize(U);
2371 Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
2372 dwarf::Form(AttrSpec.Form), DIEEntry(*NewRefDie));
2376 unsigned DwarfLinker::DIECloner::cloneBlockAttribute(DIE &Die,
2377 AttributeSpec AttrSpec,
2378 const DWARFFormValue &Val,
2379 unsigned AttrSize) {
2382 DIELoc *Loc = nullptr;
2383 DIEBlock *Block = nullptr;
2384 // Just copy the block data over.
2385 if (AttrSpec.Form == dwarf::DW_FORM_exprloc) {
2386 Loc = new (DIEAlloc) DIELoc;
2387 Linker.DIELocs.push_back(Loc);
2389 Block = new (DIEAlloc) DIEBlock;
2390 Linker.DIEBlocks.push_back(Block);
2392 Attr = Loc ? static_cast<DIEValueList *>(Loc)
2393 : static_cast<DIEValueList *>(Block);
2396 Value = DIEValue(dwarf::Attribute(AttrSpec.Attr),
2397 dwarf::Form(AttrSpec.Form), Loc);
2399 Value = DIEValue(dwarf::Attribute(AttrSpec.Attr),
2400 dwarf::Form(AttrSpec.Form), Block);
2401 ArrayRef<uint8_t> Bytes = *Val.getAsBlock();
2402 for (auto Byte : Bytes)
2403 Attr->addValue(DIEAlloc, static_cast<dwarf::Attribute>(0),
2404 dwarf::DW_FORM_data1, DIEInteger(Byte));
2405 // FIXME: If DIEBlock and DIELoc just reuses the Size field of
2406 // the DIE class, this if could be replaced by
2407 // Attr->setSize(Bytes.size()).
2408 if (Linker.Streamer) {
2409 auto *AsmPrinter = &Linker.Streamer->getAsmPrinter();
2411 Loc->ComputeSize(AsmPrinter);
2413 Block->ComputeSize(AsmPrinter);
2415 Die.addValue(DIEAlloc, Value);
2419 unsigned DwarfLinker::DIECloner::cloneAddressAttribute(
2420 DIE &Die, AttributeSpec AttrSpec, const DWARFFormValue &Val,
2421 const CompileUnit &Unit, AttributesInfo &Info) {
2422 uint64_t Addr = *Val.getAsAddress(&Unit.getOrigUnit());
2423 if (AttrSpec.Attr == dwarf::DW_AT_low_pc) {
2424 if (Die.getTag() == dwarf::DW_TAG_inlined_subroutine ||
2425 Die.getTag() == dwarf::DW_TAG_lexical_block)
2426 // The low_pc of a block or inline subroutine might get
2427 // relocated because it happens to match the low_pc of the
2428 // enclosing subprogram. To prevent issues with that, always use
2429 // the low_pc from the input DIE if relocations have been applied.
2430 Addr = (Info.OrigLowPc != UINT64_MAX ? Info.OrigLowPc : Addr) +
2432 else if (Die.getTag() == dwarf::DW_TAG_compile_unit) {
2433 Addr = Unit.getLowPc();
2434 if (Addr == UINT64_MAX)
2437 Info.HasLowPc = true;
2438 } else if (AttrSpec.Attr == dwarf::DW_AT_high_pc) {
2439 if (Die.getTag() == dwarf::DW_TAG_compile_unit) {
2440 if (uint64_t HighPc = Unit.getHighPc())
2445 // If we have a high_pc recorded for the input DIE, use
2446 // it. Otherwise (when no relocations where applied) just use the
2447 // one we just decoded.
2448 Addr = (Info.OrigHighPc ? Info.OrigHighPc : Addr) + Info.PCOffset;
2451 Die.addValue(DIEAlloc, static_cast<dwarf::Attribute>(AttrSpec.Attr),
2452 static_cast<dwarf::Form>(AttrSpec.Form), DIEInteger(Addr));
2453 return Unit.getOrigUnit().getAddressByteSize();
2456 unsigned DwarfLinker::DIECloner::cloneScalarAttribute(
2457 DIE &Die, const DWARFDebugInfoEntryMinimal &InputDIE, CompileUnit &Unit,
2458 AttributeSpec AttrSpec, const DWARFFormValue &Val, unsigned AttrSize,
2459 AttributesInfo &Info) {
2461 if (AttrSpec.Attr == dwarf::DW_AT_high_pc &&
2462 Die.getTag() == dwarf::DW_TAG_compile_unit) {
2463 if (Unit.getLowPc() == -1ULL)
2465 // Dwarf >= 4 high_pc is an size, not an address.
2466 Value = Unit.getHighPc() - Unit.getLowPc();
2467 } else if (AttrSpec.Form == dwarf::DW_FORM_sec_offset)
2468 Value = *Val.getAsSectionOffset();
2469 else if (AttrSpec.Form == dwarf::DW_FORM_sdata)
2470 Value = *Val.getAsSignedConstant();
2471 else if (auto OptionalValue = Val.getAsUnsignedConstant())
2472 Value = *OptionalValue;
2474 Linker.reportWarning(
2475 "Unsupported scalar attribute form. Dropping attribute.",
2476 &Unit.getOrigUnit(), &InputDIE);
2479 PatchLocation Patch =
2480 Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
2481 dwarf::Form(AttrSpec.Form), DIEInteger(Value));
2482 if (AttrSpec.Attr == dwarf::DW_AT_ranges)
2483 Unit.noteRangeAttribute(Die, Patch);
2485 // A more generic way to check for location attributes would be
2486 // nice, but it's very unlikely that any other attribute needs a
2488 else if (AttrSpec.Attr == dwarf::DW_AT_location ||
2489 AttrSpec.Attr == dwarf::DW_AT_frame_base)
2490 Unit.noteLocationAttribute(Patch, Info.PCOffset);
2491 else if (AttrSpec.Attr == dwarf::DW_AT_declaration && Value)
2492 Info.IsDeclaration = true;
2497 /// \brief Clone \p InputDIE's attribute described by \p AttrSpec with
2498 /// value \p Val, and add it to \p Die.
2499 /// \returns the size of the cloned attribute.
2500 unsigned DwarfLinker::DIECloner::cloneAttribute(
2501 DIE &Die, const DWARFDebugInfoEntryMinimal &InputDIE, CompileUnit &Unit,
2502 const DWARFFormValue &Val, const AttributeSpec AttrSpec, unsigned AttrSize,
2503 AttributesInfo &Info) {
2504 const DWARFUnit &U = Unit.getOrigUnit();
2506 switch (AttrSpec.Form) {
2507 case dwarf::DW_FORM_strp:
2508 case dwarf::DW_FORM_string:
2509 return cloneStringAttribute(Die, AttrSpec, Val, U);
2510 case dwarf::DW_FORM_ref_addr:
2511 case dwarf::DW_FORM_ref1:
2512 case dwarf::DW_FORM_ref2:
2513 case dwarf::DW_FORM_ref4:
2514 case dwarf::DW_FORM_ref8:
2515 return cloneDieReferenceAttribute(Die, InputDIE, AttrSpec, AttrSize, Val,
2517 case dwarf::DW_FORM_block:
2518 case dwarf::DW_FORM_block1:
2519 case dwarf::DW_FORM_block2:
2520 case dwarf::DW_FORM_block4:
2521 case dwarf::DW_FORM_exprloc:
2522 return cloneBlockAttribute(Die, AttrSpec, Val, AttrSize);
2523 case dwarf::DW_FORM_addr:
2524 return cloneAddressAttribute(Die, AttrSpec, Val, Unit, Info);
2525 case dwarf::DW_FORM_data1:
2526 case dwarf::DW_FORM_data2:
2527 case dwarf::DW_FORM_data4:
2528 case dwarf::DW_FORM_data8:
2529 case dwarf::DW_FORM_udata:
2530 case dwarf::DW_FORM_sdata:
2531 case dwarf::DW_FORM_sec_offset:
2532 case dwarf::DW_FORM_flag:
2533 case dwarf::DW_FORM_flag_present:
2534 return cloneScalarAttribute(Die, InputDIE, Unit, AttrSpec, Val, AttrSize,
2537 Linker.reportWarning(
2538 "Unsupported attribute form in cloneAttribute. Dropping.", &U,
2545 /// \brief Apply the valid relocations found by findValidRelocs() to
2546 /// the buffer \p Data, taking into account that Data is at \p BaseOffset
2547 /// in the debug_info section.
2549 /// Like for findValidRelocs(), this function must be called with
2550 /// monotonic \p BaseOffset values.
2552 /// \returns wether any reloc has been applied.
2553 bool DwarfLinker::RelocationManager::
2554 applyValidRelocs(MutableArrayRef<char> Data, uint32_t BaseOffset,
2555 bool isLittleEndian) {
2556 assert((NextValidReloc == 0 ||
2557 BaseOffset > ValidRelocs[NextValidReloc - 1].Offset) &&
2558 "BaseOffset should only be increasing.");
2559 if (NextValidReloc >= ValidRelocs.size())
2562 // Skip relocs that haven't been applied.
2563 while (NextValidReloc < ValidRelocs.size() &&
2564 ValidRelocs[NextValidReloc].Offset < BaseOffset)
2567 bool Applied = false;
2568 uint64_t EndOffset = BaseOffset + Data.size();
2569 while (NextValidReloc < ValidRelocs.size() &&
2570 ValidRelocs[NextValidReloc].Offset >= BaseOffset &&
2571 ValidRelocs[NextValidReloc].Offset < EndOffset) {
2572 const auto &ValidReloc = ValidRelocs[NextValidReloc++];
2573 assert(ValidReloc.Offset - BaseOffset < Data.size());
2574 assert(ValidReloc.Offset - BaseOffset + ValidReloc.Size <= Data.size());
2576 uint64_t Value = ValidReloc.Mapping->getValue().BinaryAddress;
2577 Value += ValidReloc.Addend;
2578 for (unsigned i = 0; i != ValidReloc.Size; ++i) {
2579 unsigned Index = isLittleEndian ? i : (ValidReloc.Size - i - 1);
2580 Buf[i] = uint8_t(Value >> (Index * 8));
2582 assert(ValidReloc.Size <= sizeof(Buf));
2583 memcpy(&Data[ValidReloc.Offset - BaseOffset], Buf, ValidReloc.Size);
2590 static bool isTypeTag(uint16_t Tag) {
2592 case dwarf::DW_TAG_array_type:
2593 case dwarf::DW_TAG_class_type:
2594 case dwarf::DW_TAG_enumeration_type:
2595 case dwarf::DW_TAG_pointer_type:
2596 case dwarf::DW_TAG_reference_type:
2597 case dwarf::DW_TAG_string_type:
2598 case dwarf::DW_TAG_structure_type:
2599 case dwarf::DW_TAG_subroutine_type:
2600 case dwarf::DW_TAG_typedef:
2601 case dwarf::DW_TAG_union_type:
2602 case dwarf::DW_TAG_ptr_to_member_type:
2603 case dwarf::DW_TAG_set_type:
2604 case dwarf::DW_TAG_subrange_type:
2605 case dwarf::DW_TAG_base_type:
2606 case dwarf::DW_TAG_const_type:
2607 case dwarf::DW_TAG_constant:
2608 case dwarf::DW_TAG_file_type:
2609 case dwarf::DW_TAG_namelist:
2610 case dwarf::DW_TAG_packed_type:
2611 case dwarf::DW_TAG_volatile_type:
2612 case dwarf::DW_TAG_restrict_type:
2613 case dwarf::DW_TAG_interface_type:
2614 case dwarf::DW_TAG_unspecified_type:
2615 case dwarf::DW_TAG_shared_type:
2624 shouldSkipAttribute(DWARFAbbreviationDeclaration::AttributeSpec AttrSpec,
2625 uint16_t Tag, bool InDebugMap, bool SkipPC,
2626 bool InFunctionScope) {
2627 switch (AttrSpec.Attr) {
2630 case dwarf::DW_AT_low_pc:
2631 case dwarf::DW_AT_high_pc:
2632 case dwarf::DW_AT_ranges:
2634 case dwarf::DW_AT_location:
2635 case dwarf::DW_AT_frame_base:
2636 // FIXME: for some reason dsymutil-classic keeps the location
2637 // attributes when they are of block type (ie. not location
2638 // lists). This is totally wrong for globals where we will keep a
2639 // wrong address. It is mostly harmless for locals, but there is
2640 // no point in keeping these anyway when the function wasn't linked.
2641 return (SkipPC || (!InFunctionScope && Tag == dwarf::DW_TAG_variable &&
2643 !DWARFFormValue(AttrSpec.Form).isFormClass(DWARFFormValue::FC_Block);
2647 DIE *DwarfLinker::DIECloner::cloneDIE(
2648 const DWARFDebugInfoEntryMinimal &InputDIE, CompileUnit &Unit,
2649 int64_t PCOffset, uint32_t OutOffset, unsigned Flags) {
2650 DWARFUnit &U = Unit.getOrigUnit();
2651 unsigned Idx = U.getDIEIndex(&InputDIE);
2652 CompileUnit::DIEInfo &Info = Unit.getInfo(Idx);
2654 // Should the DIE appear in the output?
2655 if (!Unit.getInfo(Idx).Keep)
2658 uint32_t Offset = InputDIE.getOffset();
2659 // The DIE might have been already created by a forward reference
2660 // (see cloneDieReferenceAttribute()).
2661 DIE *Die = Info.Clone;
2663 Die = Info.Clone = DIE::get(DIEAlloc, dwarf::Tag(InputDIE.getTag()));
2664 assert(Die->getTag() == InputDIE.getTag());
2665 Die->setOffset(OutOffset);
2666 if ((Unit.hasODR() || Unit.isClangModule()) &&
2667 Die->getTag() != dwarf::DW_TAG_namespace && Info.Ctxt &&
2668 Info.Ctxt != Unit.getInfo(Info.ParentIdx).Ctxt &&
2669 !Info.Ctxt->getCanonicalDIEOffset()) {
2670 // We are about to emit a DIE that is the root of its own valid
2671 // DeclContext tree. Make the current offset the canonical offset
2672 // for this context.
2673 Info.Ctxt->setCanonicalDIEOffset(OutOffset + Unit.getStartOffset());
2676 // Extract and clone every attribute.
2677 DataExtractor Data = U.getDebugInfoExtractor();
2678 // Point to the next DIE (generally there is always at least a NULL
2679 // entry after the current one). If this is a lone
2680 // DW_TAG_compile_unit without any children, point to the next unit.
2681 uint32_t NextOffset =
2682 (Idx + 1 < U.getNumDIEs())
2683 ? U.getDIEAtIndex(Idx + 1)->getOffset()
2684 : U.getNextUnitOffset();
2685 AttributesInfo AttrInfo;
2687 // We could copy the data only if we need to aply a relocation to
2688 // it. After testing, it seems there is no performance downside to
2689 // doing the copy unconditionally, and it makes the code simpler.
2690 SmallString<40> DIECopy(Data.getData().substr(Offset, NextOffset - Offset));
2691 Data = DataExtractor(DIECopy, Data.isLittleEndian(), Data.getAddressSize());
2692 // Modify the copy with relocated addresses.
2693 if (RelocMgr.applyValidRelocs(DIECopy, Offset, Data.isLittleEndian())) {
2694 // If we applied relocations, we store the value of high_pc that was
2695 // potentially stored in the input DIE. If high_pc is an address
2696 // (Dwarf version == 2), then it might have been relocated to a
2697 // totally unrelated value (because the end address in the object
2698 // file might be start address of another function which got moved
2699 // independantly by the linker). The computation of the actual
2700 // high_pc value is done in cloneAddressAttribute().
2701 AttrInfo.OrigHighPc =
2702 InputDIE.getAttributeValueAsAddress(&U, dwarf::DW_AT_high_pc, 0);
2703 // Also store the low_pc. It might get relocated in an
2704 // inline_subprogram that happens at the beginning of its
2705 // inlining function.
2706 AttrInfo.OrigLowPc =
2707 InputDIE.getAttributeValueAsAddress(&U, dwarf::DW_AT_low_pc, UINT64_MAX);
2710 // Reset the Offset to 0 as we will be working on the local copy of
2714 const auto *Abbrev = InputDIE.getAbbreviationDeclarationPtr();
2715 Offset += getULEB128Size(Abbrev->getCode());
2717 // We are entering a subprogram. Get and propagate the PCOffset.
2718 if (Die->getTag() == dwarf::DW_TAG_subprogram)
2719 PCOffset = Info.AddrAdjust;
2720 AttrInfo.PCOffset = PCOffset;
2722 if (Abbrev->getTag() == dwarf::DW_TAG_subprogram) {
2723 Flags |= TF_InFunctionScope;
2724 if (!Info.InDebugMap)
2728 bool Copied = false;
2729 for (const auto &AttrSpec : Abbrev->attributes()) {
2730 if (shouldSkipAttribute(AttrSpec, Die->getTag(), Info.InDebugMap,
2731 Flags & TF_SkipPC, Flags & TF_InFunctionScope)) {
2732 DWARFFormValue::skipValue(AttrSpec.Form, Data, &Offset, &U);
2733 // FIXME: dsymutil-classic keeps the old abbreviation around
2734 // even if it's not used. We can remove this (and the copyAbbrev
2735 // helper) as soon as bit-for-bit compatibility is not a goal anymore.
2737 copyAbbrev(*InputDIE.getAbbreviationDeclarationPtr(), Unit.hasODR());
2743 DWARFFormValue Val(AttrSpec.Form);
2744 uint32_t AttrSize = Offset;
2745 Val.extractValue(Data, &Offset, &U);
2746 AttrSize = Offset - AttrSize;
2749 cloneAttribute(*Die, InputDIE, Unit, Val, AttrSpec, AttrSize, AttrInfo);
2752 // Look for accelerator entries.
2753 uint16_t Tag = InputDIE.getTag();
2754 // FIXME: This is slightly wrong. An inline_subroutine without a
2755 // low_pc, but with AT_ranges might be interesting to get into the
2756 // accelerator tables too. For now stick with dsymutil's behavior.
2757 if ((Info.InDebugMap || AttrInfo.HasLowPc) &&
2758 Tag != dwarf::DW_TAG_compile_unit &&
2759 getDIENames(InputDIE, Unit.getOrigUnit(), AttrInfo)) {
2760 if (AttrInfo.MangledName && AttrInfo.MangledName != AttrInfo.Name)
2761 Unit.addNameAccelerator(Die, AttrInfo.MangledName,
2762 AttrInfo.MangledNameOffset,
2763 Tag == dwarf::DW_TAG_inlined_subroutine);
2765 Unit.addNameAccelerator(Die, AttrInfo.Name, AttrInfo.NameOffset,
2766 Tag == dwarf::DW_TAG_inlined_subroutine);
2767 } else if (isTypeTag(Tag) && !AttrInfo.IsDeclaration &&
2768 getDIENames(InputDIE, Unit.getOrigUnit(), AttrInfo)) {
2769 Unit.addTypeAccelerator(Die, AttrInfo.Name, AttrInfo.NameOffset);
2772 DIEAbbrev NewAbbrev = Die->generateAbbrev();
2773 // If a scope DIE is kept, we must have kept at least one child. If
2774 // it's not the case, we'll just be emitting one wasteful end of
2775 // children marker, but things won't break.
2776 if (InputDIE.hasChildren())
2777 NewAbbrev.setChildrenFlag(dwarf::DW_CHILDREN_yes);
2778 // Assign a permanent abbrev number
2779 Linker.AssignAbbrev(NewAbbrev);
2780 Die->setAbbrevNumber(NewAbbrev.getNumber());
2782 // Add the size of the abbreviation number to the output offset.
2783 OutOffset += getULEB128Size(Die->getAbbrevNumber());
2785 if (!Abbrev->hasChildren()) {
2787 Die->setSize(OutOffset - Die->getOffset());
2791 // Recursively clone children.
2792 for (auto *Child = InputDIE.getFirstChild(); Child && !Child->isNULL();
2793 Child = Child->getSibling()) {
2794 if (DIE *Clone = cloneDIE(*Child, Unit, PCOffset, OutOffset, Flags)) {
2795 Die->addChild(Clone);
2796 OutOffset = Clone->getOffset() + Clone->getSize();
2800 // Account for the end of children marker.
2801 OutOffset += sizeof(int8_t);
2803 Die->setSize(OutOffset - Die->getOffset());
2807 /// \brief Patch the input object file relevant debug_ranges entries
2808 /// and emit them in the output file. Update the relevant attributes
2809 /// to point at the new entries.
2810 void DwarfLinker::patchRangesForUnit(const CompileUnit &Unit,
2811 DWARFContext &OrigDwarf) const {
2812 DWARFDebugRangeList RangeList;
2813 const auto &FunctionRanges = Unit.getFunctionRanges();
2814 unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
2815 DataExtractor RangeExtractor(OrigDwarf.getRangeSection(),
2816 OrigDwarf.isLittleEndian(), AddressSize);
2817 auto InvalidRange = FunctionRanges.end(), CurrRange = InvalidRange;
2818 DWARFUnit &OrigUnit = Unit.getOrigUnit();
2819 const auto *OrigUnitDie = OrigUnit.getUnitDIE(false);
2820 uint64_t OrigLowPc = OrigUnitDie->getAttributeValueAsAddress(
2821 &OrigUnit, dwarf::DW_AT_low_pc, -1ULL);
2822 // Ranges addresses are based on the unit's low_pc. Compute the
2823 // offset we need to apply to adapt to the the new unit's low_pc.
2824 int64_t UnitPcOffset = 0;
2825 if (OrigLowPc != -1ULL)
2826 UnitPcOffset = int64_t(OrigLowPc) - Unit.getLowPc();
2828 for (const auto &RangeAttribute : Unit.getRangesAttributes()) {
2829 uint32_t Offset = RangeAttribute.get();
2830 RangeAttribute.set(Streamer->getRangesSectionSize());
2831 RangeList.extract(RangeExtractor, &Offset);
2832 const auto &Entries = RangeList.getEntries();
2833 if (!Entries.empty()) {
2834 const DWARFDebugRangeList::RangeListEntry &First = Entries.front();
2836 if (CurrRange == InvalidRange ||
2837 First.StartAddress + OrigLowPc < CurrRange.start() ||
2838 First.StartAddress + OrigLowPc >= CurrRange.stop()) {
2839 CurrRange = FunctionRanges.find(First.StartAddress + OrigLowPc);
2840 if (CurrRange == InvalidRange ||
2841 CurrRange.start() > First.StartAddress + OrigLowPc) {
2842 reportWarning("no mapping for range.");
2848 Streamer->emitRangesEntries(UnitPcOffset, OrigLowPc, CurrRange, Entries,
2853 /// \brief Generate the debug_aranges entries for \p Unit and if the
2854 /// unit has a DW_AT_ranges attribute, also emit the debug_ranges
2855 /// contribution for this attribute.
2856 /// FIXME: this could actually be done right in patchRangesForUnit,
2857 /// but for the sake of initial bit-for-bit compatibility with legacy
2858 /// dsymutil, we have to do it in a delayed pass.
2859 void DwarfLinker::generateUnitRanges(CompileUnit &Unit) const {
2860 auto Attr = Unit.getUnitRangesAttribute();
2862 Attr->set(Streamer->getRangesSectionSize());
2863 Streamer->emitUnitRangesEntries(Unit, static_cast<bool>(Attr));
2866 /// \brief Insert the new line info sequence \p Seq into the current
2867 /// set of already linked line info \p Rows.
2868 static void insertLineSequence(std::vector<DWARFDebugLine::Row> &Seq,
2869 std::vector<DWARFDebugLine::Row> &Rows) {
2873 if (!Rows.empty() && Rows.back().Address < Seq.front().Address) {
2874 Rows.insert(Rows.end(), Seq.begin(), Seq.end());
2879 auto InsertPoint = std::lower_bound(
2880 Rows.begin(), Rows.end(), Seq.front(),
2881 [](const DWARFDebugLine::Row &LHS, const DWARFDebugLine::Row &RHS) {
2882 return LHS.Address < RHS.Address;
2885 // FIXME: this only removes the unneeded end_sequence if the
2886 // sequences have been inserted in order. using a global sort like
2887 // described in patchLineTableForUnit() and delaying the end_sequene
2888 // elimination to emitLineTableForUnit() we can get rid of all of them.
2889 if (InsertPoint != Rows.end() &&
2890 InsertPoint->Address == Seq.front().Address && InsertPoint->EndSequence) {
2891 *InsertPoint = Seq.front();
2892 Rows.insert(InsertPoint + 1, Seq.begin() + 1, Seq.end());
2894 Rows.insert(InsertPoint, Seq.begin(), Seq.end());
2900 static void patchStmtList(DIE &Die, DIEInteger Offset) {
2901 for (auto &V : Die.values())
2902 if (V.getAttribute() == dwarf::DW_AT_stmt_list) {
2903 V = DIEValue(V.getAttribute(), V.getForm(), Offset);
2907 llvm_unreachable("Didn't find DW_AT_stmt_list in cloned DIE!");
2910 /// \brief Extract the line table for \p Unit from \p OrigDwarf, and
2911 /// recreate a relocated version of these for the address ranges that
2912 /// are present in the binary.
2913 void DwarfLinker::patchLineTableForUnit(CompileUnit &Unit,
2914 DWARFContext &OrigDwarf) {
2915 const DWARFDebugInfoEntryMinimal *CUDie = Unit.getOrigUnit().getUnitDIE();
2916 uint64_t StmtList = CUDie->getAttributeValueAsSectionOffset(
2917 &Unit.getOrigUnit(), dwarf::DW_AT_stmt_list, -1ULL);
2918 if (StmtList == -1ULL)
2921 // Update the cloned DW_AT_stmt_list with the correct debug_line offset.
2922 if (auto *OutputDIE = Unit.getOutputUnitDIE())
2923 patchStmtList(*OutputDIE, DIEInteger(Streamer->getLineSectionSize()));
2925 // Parse the original line info for the unit.
2926 DWARFDebugLine::LineTable LineTable;
2927 uint32_t StmtOffset = StmtList;
2928 StringRef LineData = OrigDwarf.getLineSection().Data;
2929 DataExtractor LineExtractor(LineData, OrigDwarf.isLittleEndian(),
2930 Unit.getOrigUnit().getAddressByteSize());
2931 LineTable.parse(LineExtractor, &OrigDwarf.getLineSection().Relocs,
2934 // This vector is the output line table.
2935 std::vector<DWARFDebugLine::Row> NewRows;
2936 NewRows.reserve(LineTable.Rows.size());
2938 // Current sequence of rows being extracted, before being inserted
2940 std::vector<DWARFDebugLine::Row> Seq;
2941 const auto &FunctionRanges = Unit.getFunctionRanges();
2942 auto InvalidRange = FunctionRanges.end(), CurrRange = InvalidRange;
2944 // FIXME: This logic is meant to generate exactly the same output as
2945 // Darwin's classic dsynutil. There is a nicer way to implement this
2946 // by simply putting all the relocated line info in NewRows and simply
2947 // sorting NewRows before passing it to emitLineTableForUnit. This
2948 // should be correct as sequences for a function should stay
2949 // together in the sorted output. There are a few corner cases that
2950 // look suspicious though, and that required to implement the logic
2951 // this way. Revisit that once initial validation is finished.
2953 // Iterate over the object file line info and extract the sequences
2954 // that correspond to linked functions.
2955 for (auto &Row : LineTable.Rows) {
2956 // Check wether we stepped out of the range. The range is
2957 // half-open, but consider accept the end address of the range if
2958 // it is marked as end_sequence in the input (because in that
2959 // case, the relocation offset is accurate and that entry won't
2960 // serve as the start of another function).
2961 if (CurrRange == InvalidRange || Row.Address < CurrRange.start() ||
2962 Row.Address > CurrRange.stop() ||
2963 (Row.Address == CurrRange.stop() && !Row.EndSequence)) {
2964 // We just stepped out of a known range. Insert a end_sequence
2965 // corresponding to the end of the range.
2966 uint64_t StopAddress = CurrRange != InvalidRange
2967 ? CurrRange.stop() + CurrRange.value()
2969 CurrRange = FunctionRanges.find(Row.Address);
2970 bool CurrRangeValid =
2971 CurrRange != InvalidRange && CurrRange.start() <= Row.Address;
2972 if (!CurrRangeValid) {
2973 CurrRange = InvalidRange;
2974 if (StopAddress != -1ULL) {
2975 // Try harder by looking in the DebugMapObject function
2976 // ranges map. There are corner cases where this finds a
2977 // valid entry. It's unclear if this is right or wrong, but
2978 // for now do as dsymutil.
2979 // FIXME: Understand exactly what cases this addresses and
2980 // potentially remove it along with the Ranges map.
2981 auto Range = Ranges.lower_bound(Row.Address);
2982 if (Range != Ranges.begin() && Range != Ranges.end())
2985 if (Range != Ranges.end() && Range->first <= Row.Address &&
2986 Range->second.first >= Row.Address) {
2987 StopAddress = Row.Address + Range->second.second;
2991 if (StopAddress != -1ULL && !Seq.empty()) {
2992 // Insert end sequence row with the computed end address, but
2993 // the same line as the previous one.
2994 auto NextLine = Seq.back();
2995 NextLine.Address = StopAddress;
2996 NextLine.EndSequence = 1;
2997 NextLine.PrologueEnd = 0;
2998 NextLine.BasicBlock = 0;
2999 NextLine.EpilogueBegin = 0;
3000 Seq.push_back(NextLine);
3001 insertLineSequence(Seq, NewRows);
3004 if (!CurrRangeValid)
3008 // Ignore empty sequences.
3009 if (Row.EndSequence && Seq.empty())
3012 // Relocate row address and add it to the current sequence.
3013 Row.Address += CurrRange.value();
3014 Seq.emplace_back(Row);
3016 if (Row.EndSequence)
3017 insertLineSequence(Seq, NewRows);
3020 // Finished extracting, now emit the line tables.
3021 uint32_t PrologueEnd = StmtList + 10 + LineTable.Prologue.PrologueLength;
3022 // FIXME: LLVM hardcodes it's prologue values. We just copy the
3023 // prologue over and that works because we act as both producer and
3024 // consumer. It would be nicer to have a real configurable line
3026 if (LineTable.Prologue.Version != 2 ||
3027 LineTable.Prologue.DefaultIsStmt != DWARF2_LINE_DEFAULT_IS_STMT ||
3028 LineTable.Prologue.OpcodeBase > 13)
3029 reportWarning("line table paramters mismatch. Cannot emit.");
3031 MCDwarfLineTableParams Params;
3032 Params.DWARF2LineOpcodeBase = LineTable.Prologue.OpcodeBase;
3033 Params.DWARF2LineBase = LineTable.Prologue.LineBase;
3034 Params.DWARF2LineRange = LineTable.Prologue.LineRange;
3035 Streamer->emitLineTableForUnit(Params,
3036 LineData.slice(StmtList + 4, PrologueEnd),
3037 LineTable.Prologue.MinInstLength, NewRows,
3038 Unit.getOrigUnit().getAddressByteSize());
3042 void DwarfLinker::emitAcceleratorEntriesForUnit(CompileUnit &Unit) {
3043 Streamer->emitPubNamesForUnit(Unit);
3044 Streamer->emitPubTypesForUnit(Unit);
3047 /// \brief Read the frame info stored in the object, and emit the
3048 /// patched frame descriptions for the linked binary.
3050 /// This is actually pretty easy as the data of the CIEs and FDEs can
3051 /// be considered as black boxes and moved as is. The only thing to do
3052 /// is to patch the addresses in the headers.
3053 void DwarfLinker::patchFrameInfoForObject(const DebugMapObject &DMO,
3054 DWARFContext &OrigDwarf,
3055 unsigned AddrSize) {
3056 StringRef FrameData = OrigDwarf.getDebugFrameSection();
3057 if (FrameData.empty())
3060 DataExtractor Data(FrameData, OrigDwarf.isLittleEndian(), 0);
3061 uint32_t InputOffset = 0;
3063 // Store the data of the CIEs defined in this object, keyed by their
3065 DenseMap<uint32_t, StringRef> LocalCIES;
3067 while (Data.isValidOffset(InputOffset)) {
3068 uint32_t EntryOffset = InputOffset;
3069 uint32_t InitialLength = Data.getU32(&InputOffset);
3070 if (InitialLength == 0xFFFFFFFF)
3071 return reportWarning("Dwarf64 bits no supported");
3073 uint32_t CIEId = Data.getU32(&InputOffset);
3074 if (CIEId == 0xFFFFFFFF) {
3075 // This is a CIE, store it.
3076 StringRef CIEData = FrameData.substr(EntryOffset, InitialLength + 4);
3077 LocalCIES[EntryOffset] = CIEData;
3078 // The -4 is to account for the CIEId we just read.
3079 InputOffset += InitialLength - 4;
3083 uint32_t Loc = Data.getUnsigned(&InputOffset, AddrSize);
3085 // Some compilers seem to emit frame info that doesn't start at
3086 // the function entry point, thus we can't just lookup the address
3087 // in the debug map. Use the linker's range map to see if the FDE
3088 // describes something that we can relocate.
3089 auto Range = Ranges.upper_bound(Loc);
3090 if (Range != Ranges.begin())
3092 if (Range == Ranges.end() || Range->first > Loc ||
3093 Range->second.first <= Loc) {
3094 // The +4 is to account for the size of the InitialLength field itself.
3095 InputOffset = EntryOffset + InitialLength + 4;
3099 // This is an FDE, and we have a mapping.
3100 // Have we already emitted a corresponding CIE?
3101 StringRef CIEData = LocalCIES[CIEId];
3102 if (CIEData.empty())
3103 return reportWarning("Inconsistent debug_frame content. Dropping.");
3105 // Look if we already emitted a CIE that corresponds to the
3106 // referenced one (the CIE data is the key of that lookup).
3107 auto IteratorInserted = EmittedCIEs.insert(
3108 std::make_pair(CIEData, Streamer->getFrameSectionSize()));
3109 // If there is no CIE yet for this ID, emit it.
3110 if (IteratorInserted.second ||
3111 // FIXME: dsymutil-classic only caches the last used CIE for
3112 // reuse. Mimic that behavior for now. Just removing that
3113 // second half of the condition and the LastCIEOffset variable
3114 // makes the code DTRT.
3115 LastCIEOffset != IteratorInserted.first->getValue()) {
3116 LastCIEOffset = Streamer->getFrameSectionSize();
3117 IteratorInserted.first->getValue() = LastCIEOffset;
3118 Streamer->emitCIE(CIEData);
3121 // Emit the FDE with updated address and CIE pointer.
3122 // (4 + AddrSize) is the size of the CIEId + initial_location
3123 // fields that will get reconstructed by emitFDE().
3124 unsigned FDERemainingBytes = InitialLength - (4 + AddrSize);
3125 Streamer->emitFDE(IteratorInserted.first->getValue(), AddrSize,
3126 Loc + Range->second.second,
3127 FrameData.substr(InputOffset, FDERemainingBytes));
3128 InputOffset += FDERemainingBytes;
3132 void DwarfLinker::DIECloner::copyAbbrev(
3133 const DWARFAbbreviationDeclaration &Abbrev, bool hasODR) {
3134 DIEAbbrev Copy(dwarf::Tag(Abbrev.getTag()),
3135 dwarf::Form(Abbrev.hasChildren()));
3137 for (const auto &Attr : Abbrev.attributes()) {
3138 uint16_t Form = Attr.Form;
3139 if (hasODR && isODRAttribute(Attr.Attr))
3140 Form = dwarf::DW_FORM_ref_addr;
3141 Copy.AddAttribute(dwarf::Attribute(Attr.Attr), dwarf::Form(Form));
3144 Linker.AssignAbbrev(Copy);
3147 static uint64_t getDwoId(const DWARFDebugInfoEntryMinimal &CUDie,
3148 const DWARFUnit &Unit) {
3150 CUDie.getAttributeValueAsUnsignedConstant(&Unit, dwarf::DW_AT_dwo_id, 0);
3152 DwoId = CUDie.getAttributeValueAsUnsignedConstant(&Unit,
3153 dwarf::DW_AT_GNU_dwo_id, 0);
3157 bool DwarfLinker::registerModuleReference(
3158 const DWARFDebugInfoEntryMinimal &CUDie, const DWARFUnit &Unit,
3159 DebugMap &ModuleMap, unsigned Indent) {
3160 std::string PCMfile =
3161 CUDie.getAttributeValueAsString(&Unit, dwarf::DW_AT_dwo_name, "");
3162 if (PCMfile.empty())
3164 CUDie.getAttributeValueAsString(&Unit, dwarf::DW_AT_GNU_dwo_name, "");
3165 if (PCMfile.empty())
3168 // Clang module DWARF skeleton CUs abuse this for the path to the module.
3169 std::string PCMpath =
3170 CUDie.getAttributeValueAsString(&Unit, dwarf::DW_AT_comp_dir, "");
3171 uint64_t DwoId = getDwoId(CUDie, Unit);
3174 CUDie.getAttributeValueAsString(&Unit, dwarf::DW_AT_name, "");
3176 reportWarning("Anonymous module skeleton CU for " + PCMfile);
3180 if (Options.Verbose) {
3181 outs().indent(Indent);
3182 outs() << "Found clang module reference " << PCMfile;
3185 auto Cached = ClangModules.find(PCMfile);
3186 if (Cached != ClangModules.end()) {
3187 if (Cached->second != DwoId)
3188 reportWarning(Twine("hash mismatch: this object file was built against a "
3189 "different version of the module ") + PCMfile);
3190 if (Options.Verbose)
3191 outs() << " [cached].\n";
3194 if (Options.Verbose)
3197 // Cyclic dependencies are disallowed by Clang, but we still
3198 // shouldn't run into an infinite loop, so mark it as processed now.
3199 ClangModules.insert({PCMfile, DwoId});
3200 loadClangModule(PCMfile, PCMpath, Name, DwoId, ModuleMap, Indent + 2);
3204 ErrorOr<const object::ObjectFile &>
3205 DwarfLinker::loadObject(BinaryHolder &BinaryHolder, DebugMapObject &Obj,
3206 const DebugMap &Map) {
3208 BinaryHolder.GetObjectFiles(Obj.getObjectFilename(), Obj.getTimestamp());
3209 if (std::error_code EC = ErrOrObjs.getError()) {
3210 reportWarning(Twine(Obj.getObjectFilename()) + ": " + EC.message());
3213 auto ErrOrObj = BinaryHolder.Get(Map.getTriple());
3214 if (std::error_code EC = ErrOrObj.getError())
3215 reportWarning(Twine(Obj.getObjectFilename()) + ": " + EC.message());
3219 void DwarfLinker::loadClangModule(StringRef Filename, StringRef ModulePath,
3220 StringRef ModuleName, uint64_t DwoId,
3221 DebugMap &ModuleMap, unsigned Indent) {
3222 SmallString<80> Path(Options.PrependPath);
3223 if (sys::path::is_relative(Filename))
3224 sys::path::append(Path, ModulePath, Filename);
3226 sys::path::append(Path, Filename);
3227 BinaryHolder ObjHolder(Options.Verbose);
3229 ModuleMap.addDebugMapObject(Path, sys::TimeValue::PosixZeroTime());
3230 auto ErrOrObj = loadObject(ObjHolder, Obj, ModuleMap);
3232 ClangModules.erase(ClangModules.find(Filename));
3236 std::unique_ptr<CompileUnit> Unit;
3238 // Setup access to the debug info.
3239 DWARFContextInMemory DwarfContext(*ErrOrObj);
3240 RelocationManager RelocMgr(*this);
3241 for (const auto &CU : DwarfContext.compile_units()) {
3242 auto *CUDie = CU->getUnitDIE(false);
3243 // Recursively get all modules imported by this one.
3244 if (!registerModuleReference(*CUDie, *CU, ModuleMap, Indent)) {
3246 errs() << Filename << ": Clang modules are expected to have exactly"
3247 << " 1 compile unit.\n";
3250 if (getDwoId(*CUDie, *CU) != DwoId)
3252 Twine("hash mismatch: this object file was built against a "
3253 "different version of the module ") + Filename);
3256 Unit = llvm::make_unique<CompileUnit>(*CU, UnitID++, !Options.NoODR,
3258 Unit->setHasInterestingContent();
3259 analyzeContextInfo(CUDie, 0, *Unit, &ODRContexts.getRoot(), StringPool,
3262 Unit->markEverythingAsKept();
3265 if (Options.Verbose) {
3266 outs().indent(Indent);
3267 outs() << "cloning .debug_info from " << Filename << "\n";
3270 DIECloner(*this, RelocMgr, DIEAlloc, MutableArrayRef<CompileUnit>(*Unit),
3272 .cloneAllCompileUnits(DwarfContext);
3275 void DwarfLinker::DIECloner::cloneAllCompileUnits(
3276 DWARFContextInMemory &DwarfContext) {
3277 if (!Linker.Streamer)
3280 for (auto &CurrentUnit : CompileUnits) {
3281 const auto *InputDIE = CurrentUnit.getOrigUnit().getUnitDIE();
3282 CurrentUnit.setStartOffset(Linker.OutputDebugInfoSize);
3283 DIE *OutputDIE = cloneDIE(*InputDIE, CurrentUnit, 0 /* PC offset */,
3284 11 /* Unit Header size */, 0);
3285 CurrentUnit.setOutputUnitDIE(OutputDIE);
3286 Linker.OutputDebugInfoSize = CurrentUnit.computeNextUnitOffset();
3287 if (Linker.Options.NoOutput)
3289 // FIXME: for compatibility with the classic dsymutil, we emit
3290 // an empty line table for the unit, even if the unit doesn't
3291 // actually exist in the DIE tree.
3292 Linker.patchLineTableForUnit(CurrentUnit, DwarfContext);
3295 Linker.patchRangesForUnit(CurrentUnit, DwarfContext);
3296 Linker.Streamer->emitLocationsForUnit(CurrentUnit, DwarfContext);
3297 Linker.emitAcceleratorEntriesForUnit(CurrentUnit);
3300 if (Linker.Options.NoOutput)
3303 // Emit all the compile unit's debug information.
3304 for (auto &CurrentUnit : CompileUnits) {
3305 Linker.generateUnitRanges(CurrentUnit);
3306 CurrentUnit.fixupForwardReferences();
3307 Linker.Streamer->emitCompileUnitHeader(CurrentUnit);
3308 if (!CurrentUnit.getOutputUnitDIE())
3310 Linker.Streamer->emitDIE(*CurrentUnit.getOutputUnitDIE());
3314 bool DwarfLinker::link(const DebugMap &Map) {
3316 if (!createStreamer(Map.getTriple(), OutputFilename))
3319 // Size of the DIEs (and headers) generated for the linked output.
3320 OutputDebugInfoSize = 0;
3321 // A unique ID that identifies each compile unit.
3323 DebugMap ModuleMap(Map.getTriple(), Map.getBinaryPath());
3325 for (const auto &Obj : Map.objects()) {
3326 CurrentDebugObject = Obj.get();
3328 if (Options.Verbose)
3329 outs() << "DEBUG MAP OBJECT: " << Obj->getObjectFilename() << "\n";
3330 auto ErrOrObj = loadObject(BinHolder, *Obj, Map);
3334 // Look for relocations that correspond to debug map entries.
3335 RelocationManager RelocMgr(*this);
3336 if (!RelocMgr.findValidRelocsInDebugInfo(*ErrOrObj, *Obj)) {
3337 if (Options.Verbose)
3338 outs() << "No valid relocations found. Skipping.\n";
3342 // Setup access to the debug info.
3343 DWARFContextInMemory DwarfContext(*ErrOrObj);
3344 startDebugObject(DwarfContext, *Obj);
3346 // In a first phase, just read in the debug info and store the DIE
3347 // parent links that we will use during the next phase.
3348 for (const auto &CU : DwarfContext.compile_units()) {
3349 auto *CUDie = CU->getUnitDIE(false);
3350 if (Options.Verbose) {
3351 outs() << "Input compilation unit:";
3352 CUDie->dump(outs(), CU.get(), 0);
3354 if (!registerModuleReference(*CUDie, *CU, ModuleMap)) {
3355 Units.emplace_back(*CU, UnitID++, !Options.NoODR, "");
3356 analyzeContextInfo(CUDie, 0, Units.back(), &ODRContexts.getRoot(),
3357 StringPool, ODRContexts);
3361 // Then mark all the DIEs that need to be present in the linked
3362 // output and collect some information about them. Note that this
3363 // loop can not be merged with the previous one becaue cross-cu
3364 // references require the ParentIdx to be setup for every CU in
3365 // the object file before calling this.
3366 for (auto &CurrentUnit : Units)
3367 lookForDIEsToKeep(RelocMgr, *CurrentUnit.getOrigUnit().getUnitDIE(), *Obj,
3370 // The calls to applyValidRelocs inside cloneDIE will walk the
3371 // reloc array again (in the same way findValidRelocsInDebugInfo()
3372 // did). We need to reset the NextValidReloc index to the beginning.
3373 RelocMgr.resetValidRelocs();
3374 if (RelocMgr.hasValidRelocs())
3375 DIECloner(*this, RelocMgr, DIEAlloc, Units, Options)
3376 .cloneAllCompileUnits(DwarfContext);
3377 if (!Options.NoOutput && !Units.empty())
3378 patchFrameInfoForObject(*Obj, DwarfContext,
3379 Units[0].getOrigUnit().getAddressByteSize());
3381 // Clean-up before starting working on the next object.
3385 // Emit everything that's global.
3386 if (!Options.NoOutput) {
3387 Streamer->emitAbbrevs(Abbreviations);
3388 Streamer->emitStrings(StringPool);
3391 return Options.NoOutput ? true : Streamer->finish(Map);
3395 /// \brief Get the offset of string \p S in the string table. This
3396 /// can insert a new element or return the offset of a preexisitng
3398 uint32_t NonRelocatableStringpool::getStringOffset(StringRef S) {
3399 if (S.empty() && !Strings.empty())
3402 std::pair<uint32_t, StringMapEntryBase *> Entry(0, nullptr);
3406 // A non-empty string can't be at offset 0, so if we have an entry
3407 // with a 0 offset, it must be a previously interned string.
3408 std::tie(It, Inserted) = Strings.insert(std::make_pair(S, Entry));
3409 if (Inserted || It->getValue().first == 0) {
3410 // Set offset and chain at the end of the entries list.
3411 It->getValue().first = CurrentEndOffset;
3412 CurrentEndOffset += S.size() + 1; // +1 for the '\0'.
3413 Last->getValue().second = &*It;
3416 return It->getValue().first;
3419 /// \brief Put \p S into the StringMap so that it gets permanent
3420 /// storage, but do not actually link it in the chain of elements
3421 /// that go into the output section. A latter call to
3422 /// getStringOffset() with the same string will chain it though.
3423 StringRef NonRelocatableStringpool::internString(StringRef S) {
3424 std::pair<uint32_t, StringMapEntryBase *> Entry(0, nullptr);
3425 auto InsertResult = Strings.insert(std::make_pair(S, Entry));
3426 return InsertResult.first->getKey();
3429 void warn(const Twine &Warning, const Twine &Context) {
3430 errs() << Twine("while processing ") + Context + ":\n";
3431 errs() << Twine("warning: ") + Warning + "\n";
3434 bool error(const Twine &Error, const Twine &Context) {
3435 errs() << Twine("while processing ") + Context + ":\n";
3436 errs() << Twine("error: ") + Error + "\n";
3440 bool linkDwarf(StringRef OutputFilename, const DebugMap &DM,
3441 const LinkOptions &Options) {
3442 DwarfLinker Linker(OutputFilename, Options);
3443 return Linker.link(DM);