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 /// An invalid context means it shouldn't be considered for uniquing, but its
170 /// not returning null, because some children of that context might be
171 /// uniquing candidates. FIXME: The invalid bit along the return value is to
172 /// emulate some dsymutil-classic functionality.
173 PointerIntPair<DeclContext *, 1>
174 getChildDeclContext(DeclContext &Context,
175 const DWARFDebugInfoEntryMinimal *DIE, CompileUnit &Unit,
176 NonRelocatableStringpool &StringPool, bool InClangModule);
178 DeclContext &getRoot() { return Root; }
181 /// \brief Stores all information relating to a compile unit, be it in
182 /// its original instance in the object file to its brand new cloned
183 /// and linked DIE tree.
186 /// \brief Information gathered about a DIE in the object file.
188 int64_t AddrAdjust; ///< Address offset to apply to the described entity.
189 DeclContext *Ctxt; ///< ODR Declaration context.
190 DIE *Clone; ///< Cloned version of that DIE.
191 uint32_t ParentIdx; ///< The index of this DIE's parent.
192 bool Keep : 1; ///< Is the DIE part of the linked output?
193 bool InDebugMap : 1;///< Was this DIE's entity found in the map?
194 bool Prune : 1; ///< Is this a pure forward declaration we can strip?
197 CompileUnit(DWARFUnit &OrigUnit, unsigned ID, bool CanUseODR,
198 StringRef ClangModuleName)
199 : OrigUnit(OrigUnit), ID(ID), LowPc(UINT64_MAX), HighPc(0), RangeAlloc(),
200 Ranges(RangeAlloc), ClangModuleName(ClangModuleName) {
201 Info.resize(OrigUnit.getNumDIEs());
203 const auto *CUDie = OrigUnit.getUnitDIE(false);
204 unsigned Lang = CUDie->getAttributeValueAsUnsignedConstant(
205 &OrigUnit, dwarf::DW_AT_language, 0);
206 HasODR = CanUseODR && (Lang == dwarf::DW_LANG_C_plus_plus ||
207 Lang == dwarf::DW_LANG_C_plus_plus_03 ||
208 Lang == dwarf::DW_LANG_C_plus_plus_11 ||
209 Lang == dwarf::DW_LANG_C_plus_plus_14 ||
210 Lang == dwarf::DW_LANG_ObjC_plus_plus);
213 CompileUnit(CompileUnit &&RHS)
214 : OrigUnit(RHS.OrigUnit), Info(std::move(RHS.Info)),
215 CUDie(std::move(RHS.CUDie)), StartOffset(RHS.StartOffset),
216 NextUnitOffset(RHS.NextUnitOffset), RangeAlloc(), Ranges(RangeAlloc) {
217 // The CompileUnit container has been 'reserve()'d with the right
218 // size. We cannot move the IntervalMap anyway.
219 llvm_unreachable("CompileUnits should not be moved.");
222 DWARFUnit &getOrigUnit() const { return OrigUnit; }
224 unsigned getUniqueID() const { return ID; }
226 DIE *getOutputUnitDIE() const { return CUDie; }
227 void setOutputUnitDIE(DIE *Die) { CUDie = Die; }
229 bool hasODR() const { return HasODR; }
230 bool isClangModule() const { return !ClangModuleName.empty(); }
231 const std::string &getClangModuleName() const { return ClangModuleName; }
233 DIEInfo &getInfo(unsigned Idx) { return Info[Idx]; }
234 const DIEInfo &getInfo(unsigned Idx) const { return Info[Idx]; }
236 uint64_t getStartOffset() const { return StartOffset; }
237 uint64_t getNextUnitOffset() const { return NextUnitOffset; }
238 void setStartOffset(uint64_t DebugInfoSize) { StartOffset = DebugInfoSize; }
240 uint64_t getLowPc() const { return LowPc; }
241 uint64_t getHighPc() const { return HighPc; }
243 Optional<PatchLocation> getUnitRangesAttribute() const {
244 return UnitRangeAttribute;
246 const FunctionIntervals &getFunctionRanges() const { return Ranges; }
247 const std::vector<PatchLocation> &getRangesAttributes() const {
248 return RangeAttributes;
251 const std::vector<std::pair<PatchLocation, int64_t>> &
252 getLocationAttributes() const {
253 return LocationAttributes;
256 void setHasInterestingContent() { HasInterestingContent = true; }
257 bool hasInterestingContent() { return HasInterestingContent; }
259 /// Mark every DIE in this unit as kept. This function also
260 /// marks variables as InDebugMap so that they appear in the
261 /// reconstructed accelerator tables.
262 void markEverythingAsKept();
264 /// \brief Compute the end offset for this unit. Must be
265 /// called after the CU's DIEs have been cloned.
266 /// \returns the next unit offset (which is also the current
267 /// debug_info section size).
268 uint64_t computeNextUnitOffset();
270 /// \brief Keep track of a forward reference to DIE \p Die in \p
271 /// RefUnit by \p Attr. The attribute should be fixed up later to
272 /// point to the absolute offset of \p Die in the debug_info section
273 /// or to the canonical offset of \p Ctxt if it is non-null.
274 void noteForwardReference(DIE *Die, const CompileUnit *RefUnit,
275 DeclContext *Ctxt, PatchLocation Attr);
277 /// \brief Apply all fixups recored by noteForwardReference().
278 void fixupForwardReferences();
280 /// \brief Add a function range [\p LowPC, \p HighPC) that is
281 /// relocatad by applying offset \p PCOffset.
282 void addFunctionRange(uint64_t LowPC, uint64_t HighPC, int64_t PCOffset);
284 /// \brief Keep track of a DW_AT_range attribute that we will need to
286 void noteRangeAttribute(const DIE &Die, PatchLocation Attr);
288 /// \brief Keep track of a location attribute pointing to a location
289 /// list in the debug_loc section.
290 void noteLocationAttribute(PatchLocation Attr, int64_t PcOffset);
292 /// \brief Add a name accelerator entry for \p Die with \p Name
293 /// which is stored in the string table at \p Offset.
294 void addNameAccelerator(const DIE *Die, const char *Name, uint32_t Offset,
295 bool SkipPubnamesSection = false);
297 /// \brief Add a type accelerator entry for \p Die with \p Name
298 /// which is stored in the string table at \p Offset.
299 void addTypeAccelerator(const DIE *Die, const char *Name, uint32_t Offset);
302 StringRef Name; ///< Name of the entry.
303 const DIE *Die; ///< DIE this entry describes.
304 uint32_t NameOffset; ///< Offset of Name in the string pool.
305 bool SkipPubSection; ///< Emit this entry only in the apple_* sections.
307 AccelInfo(StringRef Name, const DIE *Die, uint32_t NameOffset,
308 bool SkipPubSection = false)
309 : Name(Name), Die(Die), NameOffset(NameOffset),
310 SkipPubSection(SkipPubSection) {}
313 const std::vector<AccelInfo> &getPubnames() const { return Pubnames; }
314 const std::vector<AccelInfo> &getPubtypes() const { return Pubtypes; }
316 /// Get the full path for file \a FileNum in the line table
317 const char *getResolvedPath(unsigned FileNum) {
318 if (FileNum >= ResolvedPaths.size())
320 return ResolvedPaths[FileNum].size() ? ResolvedPaths[FileNum].c_str()
324 /// Set the fully resolved path for the line-table's file \a FileNum
326 void setResolvedPath(unsigned FileNum, const std::string &Path) {
327 if (ResolvedPaths.size() <= FileNum)
328 ResolvedPaths.resize(FileNum + 1);
329 ResolvedPaths[FileNum] = Path;
335 std::vector<DIEInfo> Info; ///< DIE info indexed by DIE index.
336 DIE *CUDie; ///< Root of the linked DIE tree.
338 uint64_t StartOffset;
339 uint64_t NextUnitOffset;
344 /// \brief A list of attributes to fixup with the absolute offset of
345 /// a DIE in the debug_info section.
347 /// The offsets for the attributes in this array couldn't be set while
348 /// cloning because for cross-cu forward refences the target DIE's
349 /// offset isn't known you emit the reference attribute.
350 std::vector<std::tuple<DIE *, const CompileUnit *, DeclContext *,
351 PatchLocation>> ForwardDIEReferences;
353 FunctionIntervals::Allocator RangeAlloc;
354 /// \brief The ranges in that interval map are the PC ranges for
355 /// functions in this unit, associated with the PC offset to apply
356 /// to the addresses to get the linked address.
357 FunctionIntervals Ranges;
359 /// \brief DW_AT_ranges attributes to patch after we have gathered
360 /// all the unit's function addresses.
362 std::vector<PatchLocation> RangeAttributes;
363 Optional<PatchLocation> UnitRangeAttribute;
366 /// \brief Location attributes that need to be transfered from th
367 /// original debug_loc section to the liked one. They are stored
368 /// along with the PC offset that is to be applied to their
369 /// function's address.
370 std::vector<std::pair<PatchLocation, int64_t>> LocationAttributes;
372 /// \brief Accelerator entries for the unit, both for the pub*
373 /// sections and the apple* ones.
375 std::vector<AccelInfo> Pubnames;
376 std::vector<AccelInfo> Pubtypes;
379 /// Cached resolved paths from the line table.
380 std::vector<std::string> ResolvedPaths;
382 /// Is this unit subject to the ODR rule?
384 /// Did a DIE actually contain a valid reloc?
385 bool HasInterestingContent;
386 /// If this is a Clang module, this holds the module's name.
387 std::string ClangModuleName;
390 void CompileUnit::markEverythingAsKept() {
392 // Mark everything that wasn't explicity marked for pruning.
396 uint64_t CompileUnit::computeNextUnitOffset() {
397 NextUnitOffset = StartOffset + 11 /* Header size */;
398 // The root DIE might be null, meaning that the Unit had nothing to
399 // contribute to the linked output. In that case, we will emit the
400 // unit header without any actual DIE.
402 NextUnitOffset += CUDie->getSize();
403 return NextUnitOffset;
406 /// \brief Keep track of a forward cross-cu reference from this unit
407 /// to \p Die that lives in \p RefUnit.
408 void CompileUnit::noteForwardReference(DIE *Die, const CompileUnit *RefUnit,
409 DeclContext *Ctxt, PatchLocation Attr) {
410 ForwardDIEReferences.emplace_back(Die, RefUnit, Ctxt, Attr);
413 /// \brief Apply all fixups recorded by noteForwardReference().
414 void CompileUnit::fixupForwardReferences() {
415 for (const auto &Ref : ForwardDIEReferences) {
417 const CompileUnit *RefUnit;
420 std::tie(RefDie, RefUnit, Ctxt, Attr) = Ref;
421 if (Ctxt && Ctxt->getCanonicalDIEOffset())
422 Attr.set(Ctxt->getCanonicalDIEOffset());
424 Attr.set(RefDie->getOffset() + RefUnit->getStartOffset());
428 void CompileUnit::addFunctionRange(uint64_t FuncLowPc, uint64_t FuncHighPc,
430 Ranges.insert(FuncLowPc, FuncHighPc, PcOffset);
431 this->LowPc = std::min(LowPc, FuncLowPc + PcOffset);
432 this->HighPc = std::max(HighPc, FuncHighPc + PcOffset);
435 void CompileUnit::noteRangeAttribute(const DIE &Die, PatchLocation Attr) {
436 if (Die.getTag() != dwarf::DW_TAG_compile_unit)
437 RangeAttributes.push_back(Attr);
439 UnitRangeAttribute = Attr;
442 void CompileUnit::noteLocationAttribute(PatchLocation Attr, int64_t PcOffset) {
443 LocationAttributes.emplace_back(Attr, PcOffset);
446 /// \brief Add a name accelerator entry for \p Die with \p Name
447 /// which is stored in the string table at \p Offset.
448 void CompileUnit::addNameAccelerator(const DIE *Die, const char *Name,
449 uint32_t Offset, bool SkipPubSection) {
450 Pubnames.emplace_back(Name, Die, Offset, SkipPubSection);
453 /// \brief Add a type accelerator entry for \p Die with \p Name
454 /// which is stored in the string table at \p Offset.
455 void CompileUnit::addTypeAccelerator(const DIE *Die, const char *Name,
457 Pubtypes.emplace_back(Name, Die, Offset, false);
460 /// \brief The Dwarf streaming logic
462 /// All interactions with the MC layer that is used to build the debug
463 /// information binary representation are handled in this class.
464 class DwarfStreamer {
465 /// \defgroup MCObjects MC layer objects constructed by the streamer
467 std::unique_ptr<MCRegisterInfo> MRI;
468 std::unique_ptr<MCAsmInfo> MAI;
469 std::unique_ptr<MCObjectFileInfo> MOFI;
470 std::unique_ptr<MCContext> MC;
471 MCAsmBackend *MAB; // Owned by MCStreamer
472 std::unique_ptr<MCInstrInfo> MII;
473 std::unique_ptr<MCSubtargetInfo> MSTI;
474 MCCodeEmitter *MCE; // Owned by MCStreamer
475 MCStreamer *MS; // Owned by AsmPrinter
476 std::unique_ptr<TargetMachine> TM;
477 std::unique_ptr<AsmPrinter> Asm;
480 /// \brief the file we stream the linked Dwarf to.
481 std::unique_ptr<raw_fd_ostream> OutFile;
483 uint32_t RangesSectionSize;
484 uint32_t LocSectionSize;
485 uint32_t LineSectionSize;
486 uint32_t FrameSectionSize;
488 /// \brief Emit the pubnames or pubtypes section contribution for \p
489 /// Unit into \p Sec. The data is provided in \p Names.
490 void emitPubSectionForUnit(MCSection *Sec, StringRef Name,
491 const CompileUnit &Unit,
492 const std::vector<CompileUnit::AccelInfo> &Names);
495 /// \brief Actually create the streamer and the ouptut file.
497 /// This could be done directly in the constructor, but it feels
498 /// more natural to handle errors through return value.
499 bool init(Triple TheTriple, StringRef OutputFilename);
501 /// \brief Dump the file to the disk.
502 bool finish(const DebugMap &);
504 AsmPrinter &getAsmPrinter() const { return *Asm; }
506 /// \brief Set the current output section to debug_info and change
507 /// the MC Dwarf version to \p DwarfVersion.
508 void switchToDebugInfoSection(unsigned DwarfVersion);
510 /// \brief Emit the compilation unit header for \p Unit in the
511 /// debug_info section.
513 /// As a side effect, this also switches the current Dwarf version
514 /// of the MC layer to the one of U.getOrigUnit().
515 void emitCompileUnitHeader(CompileUnit &Unit);
517 /// \brief Recursively emit the DIE tree rooted at \p Die.
518 void emitDIE(DIE &Die);
520 /// \brief Emit the abbreviation table \p Abbrevs to the
521 /// debug_abbrev section.
522 void emitAbbrevs(const std::vector<DIEAbbrev *> &Abbrevs);
524 /// \brief Emit the string table described by \p Pool.
525 void emitStrings(const NonRelocatableStringpool &Pool);
527 /// \brief Emit debug_ranges for \p FuncRange by translating the
528 /// original \p Entries.
529 void emitRangesEntries(
530 int64_t UnitPcOffset, uint64_t OrigLowPc,
531 FunctionIntervals::const_iterator FuncRange,
532 const std::vector<DWARFDebugRangeList::RangeListEntry> &Entries,
533 unsigned AddressSize);
535 /// \brief Emit debug_aranges entries for \p Unit and if \p
536 /// DoRangesSection is true, also emit the debug_ranges entries for
537 /// the DW_TAG_compile_unit's DW_AT_ranges attribute.
538 void emitUnitRangesEntries(CompileUnit &Unit, bool DoRangesSection);
540 uint32_t getRangesSectionSize() const { return RangesSectionSize; }
542 /// \brief Emit the debug_loc contribution for \p Unit by copying
543 /// the entries from \p Dwarf and offseting them. Update the
544 /// location attributes to point to the new entries.
545 void emitLocationsForUnit(const CompileUnit &Unit, DWARFContext &Dwarf);
547 /// \brief Emit the line table described in \p Rows into the
548 /// debug_line section.
549 void emitLineTableForUnit(MCDwarfLineTableParams Params,
550 StringRef PrologueBytes, unsigned MinInstLength,
551 std::vector<DWARFDebugLine::Row> &Rows,
552 unsigned AdddressSize);
554 uint32_t getLineSectionSize() const { return LineSectionSize; }
556 /// \brief Emit the .debug_pubnames contribution for \p Unit.
557 void emitPubNamesForUnit(const CompileUnit &Unit);
559 /// \brief Emit the .debug_pubtypes contribution for \p Unit.
560 void emitPubTypesForUnit(const CompileUnit &Unit);
562 /// \brief Emit a CIE.
563 void emitCIE(StringRef CIEBytes);
565 /// \brief Emit an FDE with data \p Bytes.
566 void emitFDE(uint32_t CIEOffset, uint32_t AddreSize, uint32_t Address,
569 uint32_t getFrameSectionSize() const { return FrameSectionSize; }
572 bool DwarfStreamer::init(Triple TheTriple, StringRef OutputFilename) {
573 std::string ErrorStr;
574 std::string TripleName;
575 StringRef Context = "dwarf streamer init";
578 const Target *TheTarget =
579 TargetRegistry::lookupTarget(TripleName, TheTriple, ErrorStr);
581 return error(ErrorStr, Context);
582 TripleName = TheTriple.getTriple();
584 // Create all the MC Objects.
585 MRI.reset(TheTarget->createMCRegInfo(TripleName));
587 return error(Twine("no register info for target ") + TripleName, Context);
589 MAI.reset(TheTarget->createMCAsmInfo(*MRI, TripleName));
591 return error("no asm info for target " + TripleName, Context);
593 MOFI.reset(new MCObjectFileInfo);
594 MC.reset(new MCContext(MAI.get(), MRI.get(), MOFI.get()));
595 MOFI->InitMCObjectFileInfo(TheTriple, Reloc::Default, CodeModel::Default,
598 MAB = TheTarget->createMCAsmBackend(*MRI, TripleName, "");
600 return error("no asm backend for target " + TripleName, Context);
602 MII.reset(TheTarget->createMCInstrInfo());
604 return error("no instr info info for target " + TripleName, Context);
606 MSTI.reset(TheTarget->createMCSubtargetInfo(TripleName, "", ""));
608 return error("no subtarget info for target " + TripleName, Context);
610 MCE = TheTarget->createMCCodeEmitter(*MII, *MRI, *MC);
612 return error("no code emitter for target " + TripleName, Context);
614 // Create the output file.
617 llvm::make_unique<raw_fd_ostream>(OutputFilename, EC, sys::fs::F_None);
619 return error(Twine(OutputFilename) + ": " + EC.message(), Context);
621 MS = TheTarget->createMCObjectStreamer(TheTriple, *MC, *MAB, *OutFile, MCE,
623 /*DWARFMustBeAtTheEnd*/ false);
625 return error("no object streamer for target " + TripleName, Context);
627 // Finally create the AsmPrinter we'll use to emit the DIEs.
628 TM.reset(TheTarget->createTargetMachine(TripleName, "", "", TargetOptions()));
630 return error("no target machine for target " + TripleName, Context);
632 Asm.reset(TheTarget->createAsmPrinter(*TM, std::unique_ptr<MCStreamer>(MS)));
634 return error("no asm printer for target " + TripleName, Context);
636 RangesSectionSize = 0;
639 FrameSectionSize = 0;
644 bool DwarfStreamer::finish(const DebugMap &DM) {
645 if (DM.getTriple().isOSDarwin() && !DM.getBinaryPath().empty())
646 return MachOUtils::generateDsymCompanion(DM, *MS, *OutFile);
652 /// \brief Set the current output section to debug_info and change
653 /// the MC Dwarf version to \p DwarfVersion.
654 void DwarfStreamer::switchToDebugInfoSection(unsigned DwarfVersion) {
655 MS->SwitchSection(MOFI->getDwarfInfoSection());
656 MC->setDwarfVersion(DwarfVersion);
659 /// \brief Emit the compilation unit header for \p Unit in the
660 /// debug_info section.
662 /// A Dwarf scetion header is encoded as:
663 /// uint32_t Unit length (omiting this field)
665 /// uint32_t Abbreviation table offset
666 /// uint8_t Address size
668 /// Leading to a total of 11 bytes.
669 void DwarfStreamer::emitCompileUnitHeader(CompileUnit &Unit) {
670 unsigned Version = Unit.getOrigUnit().getVersion();
671 switchToDebugInfoSection(Version);
673 // Emit size of content not including length itself. The size has
674 // already been computed in CompileUnit::computeOffsets(). Substract
675 // 4 to that size to account for the length field.
676 Asm->EmitInt32(Unit.getNextUnitOffset() - Unit.getStartOffset() - 4);
677 Asm->EmitInt16(Version);
678 // We share one abbreviations table across all units so it's always at the
679 // start of the section.
681 Asm->EmitInt8(Unit.getOrigUnit().getAddressByteSize());
684 /// \brief Emit the \p Abbrevs array as the shared abbreviation table
685 /// for the linked Dwarf file.
686 void DwarfStreamer::emitAbbrevs(const std::vector<DIEAbbrev *> &Abbrevs) {
687 MS->SwitchSection(MOFI->getDwarfAbbrevSection());
688 Asm->emitDwarfAbbrevs(Abbrevs);
691 /// \brief Recursively emit the DIE tree rooted at \p Die.
692 void DwarfStreamer::emitDIE(DIE &Die) {
693 MS->SwitchSection(MOFI->getDwarfInfoSection());
694 Asm->emitDwarfDIE(Die);
697 /// \brief Emit the debug_str section stored in \p Pool.
698 void DwarfStreamer::emitStrings(const NonRelocatableStringpool &Pool) {
699 Asm->OutStreamer->SwitchSection(MOFI->getDwarfStrSection());
700 for (auto *Entry = Pool.getFirstEntry(); Entry;
701 Entry = Pool.getNextEntry(Entry))
702 Asm->OutStreamer->EmitBytes(
703 StringRef(Entry->getKey().data(), Entry->getKey().size() + 1));
706 /// \brief Emit the debug_range section contents for \p FuncRange by
707 /// translating the original \p Entries. The debug_range section
708 /// format is totally trivial, consisting just of pairs of address
709 /// sized addresses describing the ranges.
710 void DwarfStreamer::emitRangesEntries(
711 int64_t UnitPcOffset, uint64_t OrigLowPc,
712 FunctionIntervals::const_iterator FuncRange,
713 const std::vector<DWARFDebugRangeList::RangeListEntry> &Entries,
714 unsigned AddressSize) {
715 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfRangesSection());
717 // Offset each range by the right amount.
718 int64_t PcOffset = Entries.empty() ? 0 : FuncRange.value() + UnitPcOffset;
719 for (const auto &Range : Entries) {
720 if (Range.isBaseAddressSelectionEntry(AddressSize)) {
721 warn("unsupported base address selection operation",
722 "emitting debug_ranges");
725 // Do not emit empty ranges.
726 if (Range.StartAddress == Range.EndAddress)
729 // All range entries should lie in the function range.
730 if (!(Range.StartAddress + OrigLowPc >= FuncRange.start() &&
731 Range.EndAddress + OrigLowPc <= FuncRange.stop()))
732 warn("inconsistent range data.", "emitting debug_ranges");
733 MS->EmitIntValue(Range.StartAddress + PcOffset, AddressSize);
734 MS->EmitIntValue(Range.EndAddress + PcOffset, AddressSize);
735 RangesSectionSize += 2 * AddressSize;
738 // Add the terminator entry.
739 MS->EmitIntValue(0, AddressSize);
740 MS->EmitIntValue(0, AddressSize);
741 RangesSectionSize += 2 * AddressSize;
744 /// \brief Emit the debug_aranges contribution of a unit and
745 /// if \p DoDebugRanges is true the debug_range contents for a
746 /// compile_unit level DW_AT_ranges attribute (Which are basically the
747 /// same thing with a different base address).
748 /// Just aggregate all the ranges gathered inside that unit.
749 void DwarfStreamer::emitUnitRangesEntries(CompileUnit &Unit,
750 bool DoDebugRanges) {
751 unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
752 // Gather the ranges in a vector, so that we can simplify them. The
753 // IntervalMap will have coalesced the non-linked ranges, but here
754 // we want to coalesce the linked addresses.
755 std::vector<std::pair<uint64_t, uint64_t>> Ranges;
756 const auto &FunctionRanges = Unit.getFunctionRanges();
757 for (auto Range = FunctionRanges.begin(), End = FunctionRanges.end();
758 Range != End; ++Range)
759 Ranges.push_back(std::make_pair(Range.start() + Range.value(),
760 Range.stop() + Range.value()));
762 // The object addresses where sorted, but again, the linked
763 // addresses might end up in a different order.
764 std::sort(Ranges.begin(), Ranges.end());
766 if (!Ranges.empty()) {
767 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfARangesSection());
769 MCSymbol *BeginLabel = Asm->createTempSymbol("Barange");
770 MCSymbol *EndLabel = Asm->createTempSymbol("Earange");
772 unsigned HeaderSize =
773 sizeof(int32_t) + // Size of contents (w/o this field
774 sizeof(int16_t) + // DWARF ARange version number
775 sizeof(int32_t) + // Offset of CU in the .debug_info section
776 sizeof(int8_t) + // Pointer Size (in bytes)
777 sizeof(int8_t); // Segment Size (in bytes)
779 unsigned TupleSize = AddressSize * 2;
780 unsigned Padding = OffsetToAlignment(HeaderSize, TupleSize);
782 Asm->EmitLabelDifference(EndLabel, BeginLabel, 4); // Arange length
783 Asm->OutStreamer->EmitLabel(BeginLabel);
784 Asm->EmitInt16(dwarf::DW_ARANGES_VERSION); // Version number
785 Asm->EmitInt32(Unit.getStartOffset()); // Corresponding unit's offset
786 Asm->EmitInt8(AddressSize); // Address size
787 Asm->EmitInt8(0); // Segment size
789 Asm->OutStreamer->EmitFill(Padding, 0x0);
791 for (auto Range = Ranges.begin(), End = Ranges.end(); Range != End;
793 uint64_t RangeStart = Range->first;
794 MS->EmitIntValue(RangeStart, AddressSize);
795 while ((Range + 1) != End && Range->second == (Range + 1)->first)
797 MS->EmitIntValue(Range->second - RangeStart, AddressSize);
801 Asm->OutStreamer->EmitIntValue(0, AddressSize);
802 Asm->OutStreamer->EmitIntValue(0, AddressSize);
803 Asm->OutStreamer->EmitLabel(EndLabel);
809 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfRangesSection());
810 // Offset each range by the right amount.
811 int64_t PcOffset = -Unit.getLowPc();
812 // Emit coalesced ranges.
813 for (auto Range = Ranges.begin(), End = Ranges.end(); Range != End; ++Range) {
814 MS->EmitIntValue(Range->first + PcOffset, AddressSize);
815 while (Range + 1 != End && Range->second == (Range + 1)->first)
817 MS->EmitIntValue(Range->second + PcOffset, AddressSize);
818 RangesSectionSize += 2 * AddressSize;
821 // Add the terminator entry.
822 MS->EmitIntValue(0, AddressSize);
823 MS->EmitIntValue(0, AddressSize);
824 RangesSectionSize += 2 * AddressSize;
827 /// \brief Emit location lists for \p Unit and update attribtues to
828 /// point to the new entries.
829 void DwarfStreamer::emitLocationsForUnit(const CompileUnit &Unit,
830 DWARFContext &Dwarf) {
831 const auto &Attributes = Unit.getLocationAttributes();
833 if (Attributes.empty())
836 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLocSection());
838 unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
839 const DWARFSection &InputSec = Dwarf.getLocSection();
840 DataExtractor Data(InputSec.Data, Dwarf.isLittleEndian(), AddressSize);
841 DWARFUnit &OrigUnit = Unit.getOrigUnit();
842 const auto *OrigUnitDie = OrigUnit.getUnitDIE(false);
843 int64_t UnitPcOffset = 0;
844 uint64_t OrigLowPc = OrigUnitDie->getAttributeValueAsAddress(
845 &OrigUnit, dwarf::DW_AT_low_pc, -1ULL);
846 if (OrigLowPc != -1ULL)
847 UnitPcOffset = int64_t(OrigLowPc) - Unit.getLowPc();
849 for (const auto &Attr : Attributes) {
850 uint32_t Offset = Attr.first.get();
851 Attr.first.set(LocSectionSize);
852 // This is the quantity to add to the old location address to get
853 // the correct address for the new one.
854 int64_t LocPcOffset = Attr.second + UnitPcOffset;
855 while (Data.isValidOffset(Offset)) {
856 uint64_t Low = Data.getUnsigned(&Offset, AddressSize);
857 uint64_t High = Data.getUnsigned(&Offset, AddressSize);
858 LocSectionSize += 2 * AddressSize;
859 if (Low == 0 && High == 0) {
860 Asm->OutStreamer->EmitIntValue(0, AddressSize);
861 Asm->OutStreamer->EmitIntValue(0, AddressSize);
864 Asm->OutStreamer->EmitIntValue(Low + LocPcOffset, AddressSize);
865 Asm->OutStreamer->EmitIntValue(High + LocPcOffset, AddressSize);
866 uint64_t Length = Data.getU16(&Offset);
867 Asm->OutStreamer->EmitIntValue(Length, 2);
868 // Just copy the bytes over.
869 Asm->OutStreamer->EmitBytes(
870 StringRef(InputSec.Data.substr(Offset, Length)));
872 LocSectionSize += Length + 2;
877 void DwarfStreamer::emitLineTableForUnit(MCDwarfLineTableParams Params,
878 StringRef PrologueBytes,
879 unsigned MinInstLength,
880 std::vector<DWARFDebugLine::Row> &Rows,
881 unsigned PointerSize) {
882 // Switch to the section where the table will be emitted into.
883 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLineSection());
884 MCSymbol *LineStartSym = MC->createTempSymbol();
885 MCSymbol *LineEndSym = MC->createTempSymbol();
887 // The first 4 bytes is the total length of the information for this
888 // compilation unit (not including these 4 bytes for the length).
889 Asm->EmitLabelDifference(LineEndSym, LineStartSym, 4);
890 Asm->OutStreamer->EmitLabel(LineStartSym);
892 MS->EmitBytes(PrologueBytes);
893 LineSectionSize += PrologueBytes.size() + 4;
895 SmallString<128> EncodingBuffer;
896 raw_svector_ostream EncodingOS(EncodingBuffer);
899 // We only have the dummy entry, dsymutil emits an entry with a 0
900 // address in that case.
901 MCDwarfLineAddr::Encode(*MC, Params, INT64_MAX, 0, EncodingOS);
902 MS->EmitBytes(EncodingOS.str());
903 LineSectionSize += EncodingBuffer.size();
904 MS->EmitLabel(LineEndSym);
908 // Line table state machine fields
909 unsigned FileNum = 1;
910 unsigned LastLine = 1;
912 unsigned IsStatement = 1;
914 uint64_t Address = -1ULL;
916 unsigned RowsSinceLastSequence = 0;
918 for (unsigned Idx = 0; Idx < Rows.size(); ++Idx) {
919 auto &Row = Rows[Idx];
921 int64_t AddressDelta;
922 if (Address == -1ULL) {
923 MS->EmitIntValue(dwarf::DW_LNS_extended_op, 1);
924 MS->EmitULEB128IntValue(PointerSize + 1);
925 MS->EmitIntValue(dwarf::DW_LNE_set_address, 1);
926 MS->EmitIntValue(Row.Address, PointerSize);
927 LineSectionSize += 2 + PointerSize + getULEB128Size(PointerSize + 1);
930 AddressDelta = (Row.Address - Address) / MinInstLength;
933 // FIXME: code copied and transfromed from
934 // MCDwarf.cpp::EmitDwarfLineTable. We should find a way to share
935 // this code, but the current compatibility requirement with
936 // classic dsymutil makes it hard. Revisit that once this
937 // requirement is dropped.
939 if (FileNum != Row.File) {
941 MS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
942 MS->EmitULEB128IntValue(FileNum);
943 LineSectionSize += 1 + getULEB128Size(FileNum);
945 if (Column != Row.Column) {
947 MS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
948 MS->EmitULEB128IntValue(Column);
949 LineSectionSize += 1 + getULEB128Size(Column);
952 // FIXME: We should handle the discriminator here, but dsymutil
953 // doesn' consider it, thus ignore it for now.
955 if (Isa != Row.Isa) {
957 MS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
958 MS->EmitULEB128IntValue(Isa);
959 LineSectionSize += 1 + getULEB128Size(Isa);
961 if (IsStatement != Row.IsStmt) {
962 IsStatement = Row.IsStmt;
963 MS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
964 LineSectionSize += 1;
966 if (Row.BasicBlock) {
967 MS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1);
968 LineSectionSize += 1;
971 if (Row.PrologueEnd) {
972 MS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
973 LineSectionSize += 1;
976 if (Row.EpilogueBegin) {
977 MS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);
978 LineSectionSize += 1;
981 int64_t LineDelta = int64_t(Row.Line) - LastLine;
982 if (!Row.EndSequence) {
983 MCDwarfLineAddr::Encode(*MC, Params, LineDelta, AddressDelta, EncodingOS);
984 MS->EmitBytes(EncodingOS.str());
985 LineSectionSize += EncodingBuffer.size();
986 EncodingBuffer.resize(0);
987 Address = Row.Address;
989 RowsSinceLastSequence++;
992 MS->EmitIntValue(dwarf::DW_LNS_advance_line, 1);
993 MS->EmitSLEB128IntValue(LineDelta);
994 LineSectionSize += 1 + getSLEB128Size(LineDelta);
997 MS->EmitIntValue(dwarf::DW_LNS_advance_pc, 1);
998 MS->EmitULEB128IntValue(AddressDelta);
999 LineSectionSize += 1 + getULEB128Size(AddressDelta);
1001 MCDwarfLineAddr::Encode(*MC, Params, INT64_MAX, 0, EncodingOS);
1002 MS->EmitBytes(EncodingOS.str());
1003 LineSectionSize += EncodingBuffer.size();
1004 EncodingBuffer.resize(0);
1006 LastLine = FileNum = IsStatement = 1;
1007 RowsSinceLastSequence = Column = Isa = 0;
1011 if (RowsSinceLastSequence) {
1012 MCDwarfLineAddr::Encode(*MC, Params, INT64_MAX, 0, EncodingOS);
1013 MS->EmitBytes(EncodingOS.str());
1014 LineSectionSize += EncodingBuffer.size();
1015 EncodingBuffer.resize(0);
1018 MS->EmitLabel(LineEndSym);
1021 /// \brief Emit the pubnames or pubtypes section contribution for \p
1022 /// Unit into \p Sec. The data is provided in \p Names.
1023 void DwarfStreamer::emitPubSectionForUnit(
1024 MCSection *Sec, StringRef SecName, const CompileUnit &Unit,
1025 const std::vector<CompileUnit::AccelInfo> &Names) {
1029 // Start the dwarf pubnames section.
1030 Asm->OutStreamer->SwitchSection(Sec);
1031 MCSymbol *BeginLabel = Asm->createTempSymbol("pub" + SecName + "_begin");
1032 MCSymbol *EndLabel = Asm->createTempSymbol("pub" + SecName + "_end");
1034 bool HeaderEmitted = false;
1035 // Emit the pubnames for this compilation unit.
1036 for (const auto &Name : Names) {
1037 if (Name.SkipPubSection)
1040 if (!HeaderEmitted) {
1042 Asm->EmitLabelDifference(EndLabel, BeginLabel, 4); // Length
1043 Asm->OutStreamer->EmitLabel(BeginLabel);
1044 Asm->EmitInt16(dwarf::DW_PUBNAMES_VERSION); // Version
1045 Asm->EmitInt32(Unit.getStartOffset()); // Unit offset
1046 Asm->EmitInt32(Unit.getNextUnitOffset() - Unit.getStartOffset()); // Size
1047 HeaderEmitted = true;
1049 Asm->EmitInt32(Name.Die->getOffset());
1050 Asm->OutStreamer->EmitBytes(
1051 StringRef(Name.Name.data(), Name.Name.size() + 1));
1056 Asm->EmitInt32(0); // End marker.
1057 Asm->OutStreamer->EmitLabel(EndLabel);
1060 /// \brief Emit .debug_pubnames for \p Unit.
1061 void DwarfStreamer::emitPubNamesForUnit(const CompileUnit &Unit) {
1062 emitPubSectionForUnit(MC->getObjectFileInfo()->getDwarfPubNamesSection(),
1063 "names", Unit, Unit.getPubnames());
1066 /// \brief Emit .debug_pubtypes for \p Unit.
1067 void DwarfStreamer::emitPubTypesForUnit(const CompileUnit &Unit) {
1068 emitPubSectionForUnit(MC->getObjectFileInfo()->getDwarfPubTypesSection(),
1069 "types", Unit, Unit.getPubtypes());
1072 /// \brief Emit a CIE into the debug_frame section.
1073 void DwarfStreamer::emitCIE(StringRef CIEBytes) {
1074 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfFrameSection());
1076 MS->EmitBytes(CIEBytes);
1077 FrameSectionSize += CIEBytes.size();
1080 /// \brief Emit a FDE into the debug_frame section. \p FDEBytes
1081 /// contains the FDE data without the length, CIE offset and address
1082 /// which will be replaced with the paramter values.
1083 void DwarfStreamer::emitFDE(uint32_t CIEOffset, uint32_t AddrSize,
1084 uint32_t Address, StringRef FDEBytes) {
1085 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfFrameSection());
1087 MS->EmitIntValue(FDEBytes.size() + 4 + AddrSize, 4);
1088 MS->EmitIntValue(CIEOffset, 4);
1089 MS->EmitIntValue(Address, AddrSize);
1090 MS->EmitBytes(FDEBytes);
1091 FrameSectionSize += FDEBytes.size() + 8 + AddrSize;
1094 /// \brief The core of the Dwarf linking logic.
1096 /// The link of the dwarf information from the object files will be
1097 /// driven by the selection of 'root DIEs', which are DIEs that
1098 /// describe variables or functions that are present in the linked
1099 /// binary (and thus have entries in the debug map). All the debug
1100 /// information that will be linked (the DIEs, but also the line
1101 /// tables, ranges, ...) is derived from that set of root DIEs.
1103 /// The root DIEs are identified because they contain relocations that
1104 /// correspond to a debug map entry at specific places (the low_pc for
1105 /// a function, the location for a variable). These relocations are
1106 /// called ValidRelocs in the DwarfLinker and are gathered as a very
1107 /// first step when we start processing a DebugMapObject.
1110 DwarfLinker(StringRef OutputFilename, const LinkOptions &Options)
1111 : OutputFilename(OutputFilename), Options(Options),
1112 BinHolder(Options.Verbose), LastCIEOffset(0) {}
1115 for (auto *Abbrev : Abbreviations)
1119 /// \brief Link the contents of the DebugMap.
1120 bool link(const DebugMap &);
1122 void reportWarning(const Twine &Warning, const DWARFUnit *Unit = nullptr,
1123 const DWARFDebugInfoEntryMinimal *DIE = nullptr) const;
1126 /// \brief Called at the start of a debug object link.
1127 void startDebugObject(DWARFContext &, DebugMapObject &);
1129 /// \brief Called at the end of a debug object link.
1130 void endDebugObject();
1132 /// Keeps track of relocations.
1133 class RelocationManager {
1138 const DebugMapObject::DebugMapEntry *Mapping;
1140 ValidReloc(uint32_t Offset, uint32_t Size, uint64_t Addend,
1141 const DebugMapObject::DebugMapEntry *Mapping)
1142 : Offset(Offset), Size(Size), Addend(Addend), Mapping(Mapping) {}
1144 bool operator<(const ValidReloc &RHS) const {
1145 return Offset < RHS.Offset;
1149 DwarfLinker &Linker;
1151 /// \brief The valid relocations for the current DebugMapObject.
1152 /// This vector is sorted by relocation offset.
1153 std::vector<ValidReloc> ValidRelocs;
1155 /// \brief Index into ValidRelocs of the next relocation to
1156 /// consider. As we walk the DIEs in acsending file offset and as
1157 /// ValidRelocs is sorted by file offset, keeping this index
1158 /// uptodate is all we have to do to have a cheap lookup during the
1159 /// root DIE selection and during DIE cloning.
1160 unsigned NextValidReloc;
1163 RelocationManager(DwarfLinker &Linker)
1164 : Linker(Linker), NextValidReloc(0) {}
1166 bool hasValidRelocs() const { return !ValidRelocs.empty(); }
1167 /// \brief Reset the NextValidReloc counter.
1168 void resetValidRelocs() { NextValidReloc = 0; }
1170 /// \defgroup FindValidRelocations Translate debug map into a list
1171 /// of relevant relocations
1174 bool findValidRelocsInDebugInfo(const object::ObjectFile &Obj,
1175 const DebugMapObject &DMO);
1177 bool findValidRelocs(const object::SectionRef &Section,
1178 const object::ObjectFile &Obj,
1179 const DebugMapObject &DMO);
1181 void findValidRelocsMachO(const object::SectionRef &Section,
1182 const object::MachOObjectFile &Obj,
1183 const DebugMapObject &DMO);
1186 bool hasValidRelocation(uint32_t StartOffset, uint32_t EndOffset,
1187 CompileUnit::DIEInfo &Info);
1189 bool applyValidRelocs(MutableArrayRef<char> Data, uint32_t BaseOffset,
1190 bool isLittleEndian);
1193 /// \defgroup FindRootDIEs Find DIEs corresponding to debug map entries.
1196 /// \brief Recursively walk the \p DIE tree and look for DIEs to
1197 /// keep. Store that information in \p CU's DIEInfo.
1198 void lookForDIEsToKeep(RelocationManager &RelocMgr,
1199 const DWARFDebugInfoEntryMinimal &DIE,
1200 const DebugMapObject &DMO, CompileUnit &CU,
1203 /// If this compile unit is really a skeleton CU that points to a
1204 /// clang module, register it in ClangModules and return true.
1206 /// A skeleton CU is a CU without children, a DW_AT_gnu_dwo_name
1207 /// pointing to the module, and a DW_AT_gnu_dwo_id with the module
1209 bool registerModuleReference(const DWARFDebugInfoEntryMinimal &CUDie,
1210 const DWARFUnit &Unit, DebugMap &ModuleMap,
1211 unsigned Indent = 0);
1213 /// Recursively add the debug info in this clang module .pcm
1214 /// file (and all the modules imported by it in a bottom-up fashion)
1216 void loadClangModule(StringRef Filename, StringRef ModulePath,
1217 StringRef ModuleName, uint64_t DwoId,
1218 DebugMap &ModuleMap, unsigned Indent = 0);
1220 /// \brief Flags passed to DwarfLinker::lookForDIEsToKeep
1221 enum TravesalFlags {
1222 TF_Keep = 1 << 0, ///< Mark the traversed DIEs as kept.
1223 TF_InFunctionScope = 1 << 1, ///< Current scope is a fucntion scope.
1224 TF_DependencyWalk = 1 << 2, ///< Walking the dependencies of a kept DIE.
1225 TF_ParentWalk = 1 << 3, ///< Walking up the parents of a kept DIE.
1226 TF_ODR = 1 << 4, ///< Use the ODR whhile keeping dependants.
1227 TF_SkipPC = 1 << 5, ///< Skip all location attributes.
1230 /// \brief Mark the passed DIE as well as all the ones it depends on
1232 void keepDIEAndDependencies(RelocationManager &RelocMgr,
1233 const DWARFDebugInfoEntryMinimal &DIE,
1234 CompileUnit::DIEInfo &MyInfo,
1235 const DebugMapObject &DMO, CompileUnit &CU,
1238 unsigned shouldKeepDIE(RelocationManager &RelocMgr,
1239 const DWARFDebugInfoEntryMinimal &DIE,
1240 CompileUnit &Unit, CompileUnit::DIEInfo &MyInfo,
1243 unsigned shouldKeepVariableDIE(RelocationManager &RelocMgr,
1244 const DWARFDebugInfoEntryMinimal &DIE,
1246 CompileUnit::DIEInfo &MyInfo, unsigned Flags);
1248 unsigned shouldKeepSubprogramDIE(RelocationManager &RelocMgr,
1249 const DWARFDebugInfoEntryMinimal &DIE,
1251 CompileUnit::DIEInfo &MyInfo,
1254 bool hasValidRelocation(uint32_t StartOffset, uint32_t EndOffset,
1255 CompileUnit::DIEInfo &Info);
1258 /// \defgroup Linking Methods used to link the debug information
1263 DwarfLinker &Linker;
1264 RelocationManager &RelocMgr;
1265 /// Allocator used for all the DIEValue objects.
1266 BumpPtrAllocator &DIEAlloc;
1267 MutableArrayRef<CompileUnit> CompileUnits;
1268 LinkOptions Options;
1271 DIECloner(DwarfLinker &Linker, RelocationManager &RelocMgr,
1272 BumpPtrAllocator &DIEAlloc,
1273 MutableArrayRef<CompileUnit> CompileUnits, LinkOptions &Options)
1274 : Linker(Linker), RelocMgr(RelocMgr), DIEAlloc(DIEAlloc),
1275 CompileUnits(CompileUnits), Options(Options) {}
1277 /// Recursively clone \p InputDIE into an tree of DIE objects
1278 /// where useless (as decided by lookForDIEsToKeep()) bits have been
1279 /// stripped out and addresses have been rewritten according to the
1282 /// \param OutOffset is the offset the cloned DIE in the output
1284 /// \param PCOffset (while cloning a function scope) is the offset
1285 /// applied to the entry point of the function to get the linked address.
1287 /// \returns the root of the cloned tree or null if nothing was selected.
1288 DIE *cloneDIE(const DWARFDebugInfoEntryMinimal &InputDIE, CompileUnit &U,
1289 int64_t PCOffset, uint32_t OutOffset, unsigned Flags);
1291 /// Construct the output DIE tree by cloning the DIEs we
1292 /// chose to keep above. If there are no valid relocs, then there's
1293 /// nothing to clone/emit.
1294 void cloneAllCompileUnits(DWARFContextInMemory &DwarfContext);
1297 typedef DWARFAbbreviationDeclaration::AttributeSpec AttributeSpec;
1299 /// Information gathered and exchanged between the various
1300 /// clone*Attributes helpers about the attributes of a particular DIE.
1301 struct AttributesInfo {
1302 const char *Name, *MangledName; ///< Names.
1303 uint32_t NameOffset, MangledNameOffset; ///< Offsets in the string pool.
1305 uint64_t OrigLowPc; ///< Value of AT_low_pc in the input DIE
1306 uint64_t OrigHighPc; ///< Value of AT_high_pc in the input DIE
1307 int64_t PCOffset; ///< Offset to apply to PC addresses inside a function.
1309 bool HasLowPc; ///< Does the DIE have a low_pc attribute?
1310 bool IsDeclaration; ///< Is this DIE only a declaration?
1313 : Name(nullptr), MangledName(nullptr), NameOffset(0),
1314 MangledNameOffset(0), OrigLowPc(UINT64_MAX), OrigHighPc(0),
1315 PCOffset(0), HasLowPc(false), IsDeclaration(false) {}
1318 /// Helper for cloneDIE.
1319 unsigned cloneAttribute(DIE &Die,
1320 const DWARFDebugInfoEntryMinimal &InputDIE,
1321 CompileUnit &U, const DWARFFormValue &Val,
1322 const AttributeSpec AttrSpec, unsigned AttrSize,
1323 AttributesInfo &AttrInfo);
1325 /// Clone a string attribute described by \p AttrSpec and add
1327 /// \returns the size of the new attribute.
1328 unsigned cloneStringAttribute(DIE &Die, AttributeSpec AttrSpec,
1329 const DWARFFormValue &Val,
1330 const DWARFUnit &U);
1332 /// Clone an attribute referencing another DIE and add
1334 /// \returns the size of the new attribute.
1336 cloneDieReferenceAttribute(DIE &Die,
1337 const DWARFDebugInfoEntryMinimal &InputDIE,
1338 AttributeSpec AttrSpec, unsigned AttrSize,
1339 const DWARFFormValue &Val, CompileUnit &Unit);
1341 /// Clone an attribute referencing another DIE and add
1343 /// \returns the size of the new attribute.
1344 unsigned cloneBlockAttribute(DIE &Die, AttributeSpec AttrSpec,
1345 const DWARFFormValue &Val, unsigned AttrSize);
1347 /// Clone an attribute referencing another DIE and add
1349 /// \returns the size of the new attribute.
1350 unsigned cloneAddressAttribute(DIE &Die, AttributeSpec AttrSpec,
1351 const DWARFFormValue &Val,
1352 const CompileUnit &Unit,
1353 AttributesInfo &Info);
1355 /// Clone a scalar attribute and add it to \p Die.
1356 /// \returns the size of the new attribute.
1357 unsigned cloneScalarAttribute(DIE &Die,
1358 const DWARFDebugInfoEntryMinimal &InputDIE,
1359 CompileUnit &U, AttributeSpec AttrSpec,
1360 const DWARFFormValue &Val, unsigned AttrSize,
1361 AttributesInfo &Info);
1363 /// Get the potential name and mangled name for the entity
1364 /// described by \p Die and store them in \Info if they are not
1366 /// \returns is a name was found.
1367 bool getDIENames(const DWARFDebugInfoEntryMinimal &Die, DWARFUnit &U,
1368 AttributesInfo &Info);
1370 /// Create a copy of abbreviation Abbrev.
1371 void copyAbbrev(const DWARFAbbreviationDeclaration &Abbrev, bool hasODR);
1374 /// \brief Assign an abbreviation number to \p Abbrev
1375 void AssignAbbrev(DIEAbbrev &Abbrev);
1377 /// \brief FoldingSet that uniques the abbreviations.
1378 FoldingSet<DIEAbbrev> AbbreviationsSet;
1379 /// \brief Storage for the unique Abbreviations.
1380 /// This is passed to AsmPrinter::emitDwarfAbbrevs(), thus it cannot
1381 /// be changed to a vecot of unique_ptrs.
1382 std::vector<DIEAbbrev *> Abbreviations;
1384 /// \brief Compute and emit debug_ranges section for \p Unit, and
1385 /// patch the attributes referencing it.
1386 void patchRangesForUnit(const CompileUnit &Unit, DWARFContext &Dwarf) const;
1388 /// \brief Generate and emit the DW_AT_ranges attribute for a
1389 /// compile_unit if it had one.
1390 void generateUnitRanges(CompileUnit &Unit) const;
1392 /// \brief Extract the line tables fromt he original dwarf, extract
1393 /// the relevant parts according to the linked function ranges and
1394 /// emit the result in the debug_line section.
1395 void patchLineTableForUnit(CompileUnit &Unit, DWARFContext &OrigDwarf);
1397 /// \brief Emit the accelerator entries for \p Unit.
1398 void emitAcceleratorEntriesForUnit(CompileUnit &Unit);
1400 /// \brief Patch the frame info for an object file and emit it.
1401 void patchFrameInfoForObject(const DebugMapObject &, DWARFContext &,
1402 unsigned AddressSize);
1404 /// \brief DIELoc objects that need to be destructed (but not freed!).
1405 std::vector<DIELoc *> DIELocs;
1406 /// \brief DIEBlock objects that need to be destructed (but not freed!).
1407 std::vector<DIEBlock *> DIEBlocks;
1408 /// \brief Allocator used for all the DIEValue objects.
1409 BumpPtrAllocator DIEAlloc;
1412 /// ODR Contexts for that link.
1413 DeclContextTree ODRContexts;
1415 /// \defgroup Helpers Various helper methods.
1418 bool createStreamer(Triple TheTriple, StringRef OutputFilename);
1420 /// \brief Attempt to load a debug object from disk.
1421 ErrorOr<const object::ObjectFile &> loadObject(BinaryHolder &BinaryHolder,
1422 DebugMapObject &Obj,
1423 const DebugMap &Map);
1426 std::string OutputFilename;
1427 LinkOptions Options;
1428 BinaryHolder BinHolder;
1429 std::unique_ptr<DwarfStreamer> Streamer;
1430 uint64_t OutputDebugInfoSize;
1431 unsigned UnitID; ///< A unique ID that identifies each compile unit.
1433 /// The units of the current debug map object.
1434 std::vector<CompileUnit> Units;
1436 /// The debug map object currently under consideration.
1437 DebugMapObject *CurrentDebugObject;
1439 /// \brief The Dwarf string pool
1440 NonRelocatableStringpool StringPool;
1442 /// \brief This map is keyed by the entry PC of functions in that
1443 /// debug object and the associated value is a pair storing the
1444 /// corresponding end PC and the offset to apply to get the linked
1447 /// See startDebugObject() for a more complete description of its use.
1448 std::map<uint64_t, std::pair<uint64_t, int64_t>> Ranges;
1450 /// \brief The CIEs that have been emitted in the output
1451 /// section. The actual CIE data serves a the key to this StringMap,
1452 /// this takes care of comparing the semantics of CIEs defined in
1453 /// different object files.
1454 StringMap<uint32_t> EmittedCIEs;
1456 /// Offset of the last CIE that has been emitted in the output
1457 /// debug_frame section.
1458 uint32_t LastCIEOffset;
1460 /// Mapping the PCM filename to the DwoId.
1461 StringMap<uint64_t> ClangModules;
1464 /// Similar to DWARFUnitSection::getUnitForOffset(), but returning our
1465 /// CompileUnit object instead.
1466 static CompileUnit *getUnitForOffset(MutableArrayRef<CompileUnit> Units,
1469 std::upper_bound(Units.begin(), Units.end(), Offset,
1470 [](uint32_t LHS, const CompileUnit &RHS) {
1471 return LHS < RHS.getOrigUnit().getNextUnitOffset();
1473 return CU != Units.end() ? &*CU : nullptr;
1476 /// Resolve the DIE attribute reference that has been
1477 /// extracted in \p RefValue. The resulting DIE migh be in another
1478 /// CompileUnit which is stored into \p ReferencedCU.
1479 /// \returns null if resolving fails for any reason.
1480 static const DWARFDebugInfoEntryMinimal *resolveDIEReference(
1481 const DwarfLinker &Linker, MutableArrayRef<CompileUnit> Units,
1482 const DWARFFormValue &RefValue, const DWARFUnit &Unit,
1483 const DWARFDebugInfoEntryMinimal &DIE, CompileUnit *&RefCU) {
1484 assert(RefValue.isFormClass(DWARFFormValue::FC_Reference));
1485 uint64_t RefOffset = *RefValue.getAsReference(&Unit);
1487 if ((RefCU = getUnitForOffset(Units, RefOffset)))
1488 if (const auto *RefDie = RefCU->getOrigUnit().getDIEForOffset(RefOffset))
1491 Linker.reportWarning("could not find referenced DIE", &Unit, &DIE);
1495 /// \returns whether the passed \a Attr type might contain a DIE
1496 /// reference suitable for ODR uniquing.
1497 static bool isODRAttribute(uint16_t Attr) {
1501 case dwarf::DW_AT_type:
1502 case dwarf::DW_AT_containing_type:
1503 case dwarf::DW_AT_specification:
1504 case dwarf::DW_AT_abstract_origin:
1505 case dwarf::DW_AT_import:
1508 llvm_unreachable("Improper attribute.");
1511 /// Set the last DIE/CU a context was seen in and, possibly invalidate
1512 /// the context if it is ambiguous.
1514 /// In the current implementation, we don't handle overloaded
1515 /// functions well, because the argument types are not taken into
1516 /// account when computing the DeclContext tree.
1518 /// Some of this is mitigated byt using mangled names that do contain
1519 /// the arguments types, but sometimes (eg. with function templates)
1520 /// we don't have that. In that case, just do not unique anything that
1521 /// refers to the contexts we are not able to distinguish.
1523 /// If a context that is not a namespace appears twice in the same CU,
1524 /// we know it is ambiguous. Make it invalid.
1525 bool DeclContext::setLastSeenDIE(CompileUnit &U,
1526 const DWARFDebugInfoEntryMinimal *Die) {
1527 if (LastSeenCompileUnitID == U.getUniqueID()) {
1528 DWARFUnit &OrigUnit = U.getOrigUnit();
1529 uint32_t FirstIdx = OrigUnit.getDIEIndex(LastSeenDIE);
1530 U.getInfo(FirstIdx).Ctxt = nullptr;
1534 LastSeenCompileUnitID = U.getUniqueID();
1539 PointerIntPair<DeclContext *, 1> DeclContextTree::getChildDeclContext(
1540 DeclContext &Context, const DWARFDebugInfoEntryMinimal *DIE, CompileUnit &U,
1541 NonRelocatableStringpool &StringPool, bool InClangModule) {
1542 unsigned Tag = DIE->getTag();
1544 // FIXME: dsymutil-classic compat: We should bail out here if we
1545 // have a specification or an abstract_origin. We will get the
1546 // parent context wrong here.
1550 // By default stop gathering child contexts.
1551 return PointerIntPair<DeclContext *, 1>(nullptr);
1552 case dwarf::DW_TAG_module:
1554 case dwarf::DW_TAG_compile_unit:
1555 return PointerIntPair<DeclContext *, 1>(&Context);
1556 case dwarf::DW_TAG_subprogram:
1557 // Do not unique anything inside CU local functions.
1558 if ((Context.getTag() == dwarf::DW_TAG_namespace ||
1559 Context.getTag() == dwarf::DW_TAG_compile_unit) &&
1560 !DIE->getAttributeValueAsUnsignedConstant(&U.getOrigUnit(),
1561 dwarf::DW_AT_external, 0))
1562 return PointerIntPair<DeclContext *, 1>(nullptr);
1564 case dwarf::DW_TAG_member:
1565 case dwarf::DW_TAG_namespace:
1566 case dwarf::DW_TAG_structure_type:
1567 case dwarf::DW_TAG_class_type:
1568 case dwarf::DW_TAG_union_type:
1569 case dwarf::DW_TAG_enumeration_type:
1570 case dwarf::DW_TAG_typedef:
1571 // Artificial things might be ambiguous, because they might be
1572 // created on demand. For example implicitely defined constructors
1573 // are ambiguous because of the way we identify contexts, and they
1574 // won't be generated everytime everywhere.
1575 if (DIE->getAttributeValueAsUnsignedConstant(&U.getOrigUnit(),
1576 dwarf::DW_AT_artificial, 0))
1577 return PointerIntPair<DeclContext *, 1>(nullptr);
1581 const char *Name = DIE->getName(&U.getOrigUnit(), DINameKind::LinkageName);
1582 const char *ShortName = DIE->getName(&U.getOrigUnit(), DINameKind::ShortName);
1584 StringRef ShortNameRef;
1588 NameRef = StringPool.internString(Name);
1589 else if (Tag == dwarf::DW_TAG_namespace)
1590 // FIXME: For dsymutil-classic compatibility. I think uniquing
1591 // within anonymous namespaces is wrong. There is no ODR guarantee
1593 NameRef = StringPool.internString("(anonymous namespace)");
1595 if (ShortName && ShortName != Name)
1596 ShortNameRef = StringPool.internString(ShortName);
1598 ShortNameRef = NameRef;
1600 if (Tag != dwarf::DW_TAG_class_type && Tag != dwarf::DW_TAG_structure_type &&
1601 Tag != dwarf::DW_TAG_union_type &&
1602 Tag != dwarf::DW_TAG_enumeration_type && NameRef.empty())
1603 return PointerIntPair<DeclContext *, 1>(nullptr);
1607 unsigned ByteSize = UINT32_MAX;
1609 if (!InClangModule) {
1610 // Gather some discriminating data about the DeclContext we will be
1611 // creating: File, line number and byte size. This shouldn't be
1612 // necessary, because the ODR is just about names, but given that we
1613 // do some approximations with overloaded functions and anonymous
1614 // namespaces, use these additional data points to make the process
1615 // safer. This is disabled for clang modules, because forward
1616 // declarations of module-defined types do not have a file and line.
1617 ByteSize = DIE->getAttributeValueAsUnsignedConstant(
1618 &U.getOrigUnit(), dwarf::DW_AT_byte_size, UINT64_MAX);
1619 if (Tag != dwarf::DW_TAG_namespace || !Name) {
1620 if (unsigned FileNum = DIE->getAttributeValueAsUnsignedConstant(
1621 &U.getOrigUnit(), dwarf::DW_AT_decl_file, 0)) {
1622 if (const auto *LT = U.getOrigUnit().getContext().getLineTableForUnit(
1623 &U.getOrigUnit())) {
1624 // FIXME: dsymutil-classic compatibility. I'd rather not
1625 // unique anything in anonymous namespaces, but if we do, then
1626 // verify that the file and line correspond.
1627 if (!Name && Tag == dwarf::DW_TAG_namespace)
1630 // FIXME: Passing U.getOrigUnit().getCompilationDir()
1631 // instead of "" would allow more uniquing, but for now, do
1632 // it this way to match dsymutil-classic.
1633 if (LT->getFileNameByIndex(
1635 DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath,
1637 Line = DIE->getAttributeValueAsUnsignedConstant(
1638 &U.getOrigUnit(), dwarf::DW_AT_decl_line, 0);
1639 #ifdef HAVE_REALPATH
1640 // Cache the resolved paths, because calling realpath is expansive.
1641 if (const char *ResolvedPath = U.getResolvedPath(FileNum)) {
1642 File = ResolvedPath;
1644 char RealPath[PATH_MAX + 1];
1645 RealPath[PATH_MAX] = 0;
1646 if (::realpath(File.c_str(), RealPath))
1648 U.setResolvedPath(FileNum, File);
1651 FileRef = StringPool.internString(File);
1658 if (!Line && NameRef.empty())
1659 return PointerIntPair<DeclContext *, 1>(nullptr);
1661 // We hash NameRef, which is the mangled name, in order to get most
1662 // overloaded functions resolve correctly.
1664 // Strictly speaking, hashing the Tag is only necessary for a
1665 // DW_TAG_module, to prevent uniquing of a module and a namespace
1666 // with the same name.
1668 // FIXME: dsymutil-classic won't unique the same type presented
1669 // once as a struct and once as a class. Using the Tag in the fully
1670 // qualified name hash to get the same effect.
1671 unsigned Hash = hash_combine(Context.getQualifiedNameHash(), Tag, NameRef);
1673 // FIXME: dsymutil-classic compatibility: when we don't have a name,
1674 // use the filename.
1675 if (Tag == dwarf::DW_TAG_namespace && NameRef == "(anonymous namespace)")
1676 Hash = hash_combine(Hash, FileRef);
1678 // Now look if this context already exists.
1679 DeclContext Key(Hash, Line, ByteSize, Tag, NameRef, FileRef, Context);
1680 auto ContextIter = Contexts.find(&Key);
1682 if (ContextIter == Contexts.end()) {
1683 // The context wasn't found.
1685 DeclContext *NewContext =
1686 new (Allocator) DeclContext(Hash, Line, ByteSize, Tag, NameRef, FileRef,
1687 Context, DIE, U.getUniqueID());
1688 std::tie(ContextIter, Inserted) = Contexts.insert(NewContext);
1689 assert(Inserted && "Failed to insert DeclContext");
1691 } else if (Tag != dwarf::DW_TAG_namespace &&
1692 !(*ContextIter)->setLastSeenDIE(U, DIE)) {
1693 // The context was found, but it is ambiguous with another context
1694 // in the same file. Mark it invalid.
1695 return PointerIntPair<DeclContext *, 1>(*ContextIter, /* Invalid= */ 1);
1698 assert(ContextIter != Contexts.end());
1699 // FIXME: dsymutil-classic compatibility. Union types aren't
1700 // uniques, but their children might be.
1701 if ((Tag == dwarf::DW_TAG_subprogram &&
1702 Context.getTag() != dwarf::DW_TAG_structure_type &&
1703 Context.getTag() != dwarf::DW_TAG_class_type) ||
1704 (Tag == dwarf::DW_TAG_union_type))
1705 return PointerIntPair<DeclContext *, 1>(*ContextIter, /* Invalid= */ 1);
1707 return PointerIntPair<DeclContext *, 1>(*ContextIter);
1710 bool DwarfLinker::DIECloner::getDIENames(const DWARFDebugInfoEntryMinimal &Die,
1711 DWARFUnit &U, AttributesInfo &Info) {
1712 // FIXME: a bit wasteful as the first getName might return the
1714 if (!Info.MangledName &&
1715 (Info.MangledName = Die.getName(&U, DINameKind::LinkageName)))
1716 Info.MangledNameOffset =
1717 Linker.StringPool.getStringOffset(Info.MangledName);
1719 if (!Info.Name && (Info.Name = Die.getName(&U, DINameKind::ShortName)))
1720 Info.NameOffset = Linker.StringPool.getStringOffset(Info.Name);
1722 return Info.Name || Info.MangledName;
1725 /// \brief Report a warning to the user, optionaly including
1726 /// information about a specific \p DIE related to the warning.
1727 void DwarfLinker::reportWarning(const Twine &Warning, const DWARFUnit *Unit,
1728 const DWARFDebugInfoEntryMinimal *DIE) const {
1729 StringRef Context = "<debug map>";
1730 if (CurrentDebugObject)
1731 Context = CurrentDebugObject->getObjectFilename();
1732 warn(Warning, Context);
1734 if (!Options.Verbose || !DIE)
1737 errs() << " in DIE:\n";
1738 DIE->dump(errs(), const_cast<DWARFUnit *>(Unit), 0 /* RecurseDepth */,
1742 bool DwarfLinker::createStreamer(Triple TheTriple, StringRef OutputFilename) {
1743 if (Options.NoOutput)
1746 Streamer = llvm::make_unique<DwarfStreamer>();
1747 return Streamer->init(TheTriple, OutputFilename);
1750 /// Recursive helper to build the global DeclContext information and
1751 /// gather the child->parent relationships in the original compile unit.
1753 /// \return true when this DIE and all of its children are only
1754 /// forward declarations to types defined in external clang modules
1755 /// (i.e., forward declarations that are children of a DW_TAG_module).
1756 static bool analyzeContextInfo(const DWARFDebugInfoEntryMinimal *DIE,
1757 unsigned ParentIdx, CompileUnit &CU,
1758 DeclContext *CurrentDeclContext,
1759 NonRelocatableStringpool &StringPool,
1760 DeclContextTree &Contexts,
1761 bool InImportedModule = false) {
1762 unsigned MyIdx = CU.getOrigUnit().getDIEIndex(DIE);
1763 CompileUnit::DIEInfo &Info = CU.getInfo(MyIdx);
1765 // Clang imposes an ODR on modules(!) regardless of the language:
1766 // "The module-id should consist of only a single identifier,
1767 // which provides the name of the module being defined. Each
1768 // module shall have a single definition."
1770 // This does not extend to the types inside the modules:
1771 // "[I]n C, this implies that if two structs are defined in
1772 // different submodules with the same name, those two types are
1773 // distinct types (but may be compatible types if their
1774 // definitions match)."
1776 // We treat non-C++ modules like namespaces for this reason.
1777 if (DIE->getTag() == dwarf::DW_TAG_module && ParentIdx == 0 &&
1778 DIE->getAttributeValueAsString(&CU.getOrigUnit(), dwarf::DW_AT_name,
1779 "") != CU.getClangModuleName()) {
1780 InImportedModule = true;
1783 Info.ParentIdx = ParentIdx;
1784 bool InClangModule = CU.isClangModule() || InImportedModule;
1785 if (CU.hasODR() || InClangModule) {
1786 if (CurrentDeclContext) {
1787 auto PtrInvalidPair = Contexts.getChildDeclContext(
1788 *CurrentDeclContext, DIE, CU, StringPool, InClangModule);
1789 CurrentDeclContext = PtrInvalidPair.getPointer();
1791 PtrInvalidPair.getInt() ? nullptr : PtrInvalidPair.getPointer();
1793 Info.Ctxt = CurrentDeclContext = nullptr;
1796 Info.Prune = InImportedModule;
1797 if (DIE->hasChildren())
1798 for (auto *Child = DIE->getFirstChild(); Child && !Child->isNULL();
1799 Child = Child->getSibling())
1800 Info.Prune &= analyzeContextInfo(Child, MyIdx, CU, CurrentDeclContext,
1801 StringPool, Contexts, InImportedModule);
1803 // Prune this DIE if it is either a forward declaration inside a
1804 // DW_TAG_module or a DW_TAG_module that contains nothing but
1805 // forward declarations.
1806 Info.Prune &= (DIE->getTag() == dwarf::DW_TAG_module) ||
1807 DIE->getAttributeValueAsUnsignedConstant(
1808 &CU.getOrigUnit(), dwarf::DW_AT_declaration, 0);
1810 // Don't prune it if there is no definition for the DIE.
1811 Info.Prune &= Info.Ctxt && Info.Ctxt->getCanonicalDIEOffset();
1816 static bool dieNeedsChildrenToBeMeaningful(uint32_t Tag) {
1820 case dwarf::DW_TAG_subprogram:
1821 case dwarf::DW_TAG_lexical_block:
1822 case dwarf::DW_TAG_subroutine_type:
1823 case dwarf::DW_TAG_structure_type:
1824 case dwarf::DW_TAG_class_type:
1825 case dwarf::DW_TAG_union_type:
1828 llvm_unreachable("Invalid Tag");
1831 static unsigned getRefAddrSize(const DWARFUnit &U) {
1832 if (U.getVersion() == 2)
1833 return U.getAddressByteSize();
1837 void DwarfLinker::startDebugObject(DWARFContext &Dwarf, DebugMapObject &Obj) {
1838 Units.reserve(Dwarf.getNumCompileUnits());
1839 // Iterate over the debug map entries and put all the ones that are
1840 // functions (because they have a size) into the Ranges map. This
1841 // map is very similar to the FunctionRanges that are stored in each
1842 // unit, with 2 notable differences:
1843 // - obviously this one is global, while the other ones are per-unit.
1844 // - this one contains not only the functions described in the DIE
1845 // tree, but also the ones that are only in the debug map.
1846 // The latter information is required to reproduce dsymutil's logic
1847 // while linking line tables. The cases where this information
1848 // matters look like bugs that need to be investigated, but for now
1849 // we need to reproduce dsymutil's behavior.
1850 // FIXME: Once we understood exactly if that information is needed,
1851 // maybe totally remove this (or try to use it to do a real
1852 // -gline-tables-only on Darwin.
1853 for (const auto &Entry : Obj.symbols()) {
1854 const auto &Mapping = Entry.getValue();
1856 Ranges[Mapping.ObjectAddress] = std::make_pair(
1857 Mapping.ObjectAddress + Mapping.Size,
1858 int64_t(Mapping.BinaryAddress) - Mapping.ObjectAddress);
1862 void DwarfLinker::endDebugObject() {
1866 for (auto I = DIEBlocks.begin(), E = DIEBlocks.end(); I != E; ++I)
1868 for (auto I = DIELocs.begin(), E = DIELocs.end(); I != E; ++I)
1876 /// \brief Iterate over the relocations of the given \p Section and
1877 /// store the ones that correspond to debug map entries into the
1878 /// ValidRelocs array.
1879 void DwarfLinker::RelocationManager::
1880 findValidRelocsMachO(const object::SectionRef &Section,
1881 const object::MachOObjectFile &Obj,
1882 const DebugMapObject &DMO) {
1884 Section.getContents(Contents);
1885 DataExtractor Data(Contents, Obj.isLittleEndian(), 0);
1887 for (const object::RelocationRef &Reloc : Section.relocations()) {
1888 object::DataRefImpl RelocDataRef = Reloc.getRawDataRefImpl();
1889 MachO::any_relocation_info MachOReloc = Obj.getRelocation(RelocDataRef);
1890 unsigned RelocSize = 1 << Obj.getAnyRelocationLength(MachOReloc);
1891 uint64_t Offset64 = Reloc.getOffset();
1892 if ((RelocSize != 4 && RelocSize != 8)) {
1893 Linker.reportWarning(" unsupported relocation in debug_info section.");
1896 uint32_t Offset = Offset64;
1897 // Mach-o uses REL relocations, the addend is at the relocation offset.
1898 uint64_t Addend = Data.getUnsigned(&Offset, RelocSize);
1900 auto Sym = Reloc.getSymbol();
1901 if (Sym != Obj.symbol_end()) {
1902 ErrorOr<StringRef> SymbolName = Sym->getName();
1904 Linker.reportWarning("error getting relocation symbol name.");
1907 if (const auto *Mapping = DMO.lookupSymbol(*SymbolName))
1908 ValidRelocs.emplace_back(Offset64, RelocSize, Addend, Mapping);
1909 } else if (const auto *Mapping = DMO.lookupObjectAddress(Addend)) {
1910 // Do not store the addend. The addend was the address of the
1911 // symbol in the object file, the address in the binary that is
1912 // stored in the debug map doesn't need to be offseted.
1913 ValidRelocs.emplace_back(Offset64, RelocSize, 0, Mapping);
1918 /// \brief Dispatch the valid relocation finding logic to the
1919 /// appropriate handler depending on the object file format.
1920 bool DwarfLinker::RelocationManager::findValidRelocs(
1921 const object::SectionRef &Section, const object::ObjectFile &Obj,
1922 const DebugMapObject &DMO) {
1923 // Dispatch to the right handler depending on the file type.
1924 if (auto *MachOObj = dyn_cast<object::MachOObjectFile>(&Obj))
1925 findValidRelocsMachO(Section, *MachOObj, DMO);
1927 Linker.reportWarning(Twine("unsupported object file type: ") +
1930 if (ValidRelocs.empty())
1933 // Sort the relocations by offset. We will walk the DIEs linearly in
1934 // the file, this allows us to just keep an index in the relocation
1935 // array that we advance during our walk, rather than resorting to
1936 // some associative container. See DwarfLinker::NextValidReloc.
1937 std::sort(ValidRelocs.begin(), ValidRelocs.end());
1941 /// \brief Look for relocations in the debug_info section that match
1942 /// entries in the debug map. These relocations will drive the Dwarf
1943 /// link by indicating which DIEs refer to symbols present in the
1945 /// \returns wether there are any valid relocations in the debug info.
1946 bool DwarfLinker::RelocationManager::
1947 findValidRelocsInDebugInfo(const object::ObjectFile &Obj,
1948 const DebugMapObject &DMO) {
1949 // Find the debug_info section.
1950 for (const object::SectionRef &Section : Obj.sections()) {
1951 StringRef SectionName;
1952 Section.getName(SectionName);
1953 SectionName = SectionName.substr(SectionName.find_first_not_of("._"));
1954 if (SectionName != "debug_info")
1956 return findValidRelocs(Section, Obj, DMO);
1961 /// \brief Checks that there is a relocation against an actual debug
1962 /// map entry between \p StartOffset and \p NextOffset.
1964 /// This function must be called with offsets in strictly ascending
1965 /// order because it never looks back at relocations it already 'went past'.
1966 /// \returns true and sets Info.InDebugMap if it is the case.
1967 bool DwarfLinker::RelocationManager::
1968 hasValidRelocation(uint32_t StartOffset, uint32_t EndOffset,
1969 CompileUnit::DIEInfo &Info) {
1970 assert(NextValidReloc == 0 ||
1971 StartOffset > ValidRelocs[NextValidReloc - 1].Offset);
1972 if (NextValidReloc >= ValidRelocs.size())
1975 uint64_t RelocOffset = ValidRelocs[NextValidReloc].Offset;
1977 // We might need to skip some relocs that we didn't consider. For
1978 // example the high_pc of a discarded DIE might contain a reloc that
1979 // is in the list because it actually corresponds to the start of a
1980 // function that is in the debug map.
1981 while (RelocOffset < StartOffset && NextValidReloc < ValidRelocs.size() - 1)
1982 RelocOffset = ValidRelocs[++NextValidReloc].Offset;
1984 if (RelocOffset < StartOffset || RelocOffset >= EndOffset)
1987 const auto &ValidReloc = ValidRelocs[NextValidReloc++];
1988 const auto &Mapping = ValidReloc.Mapping->getValue();
1989 if (Linker.Options.Verbose)
1990 outs() << "Found valid debug map entry: " << ValidReloc.Mapping->getKey()
1991 << " " << format("\t%016" PRIx64 " => %016" PRIx64,
1992 uint64_t(Mapping.ObjectAddress),
1993 uint64_t(Mapping.BinaryAddress));
1995 Info.AddrAdjust = int64_t(Mapping.BinaryAddress) + ValidReloc.Addend -
1996 Mapping.ObjectAddress;
1997 Info.InDebugMap = true;
2001 /// \brief Get the starting and ending (exclusive) offset for the
2002 /// attribute with index \p Idx descibed by \p Abbrev. \p Offset is
2003 /// supposed to point to the position of the first attribute described
2005 /// \return [StartOffset, EndOffset) as a pair.
2006 static std::pair<uint32_t, uint32_t>
2007 getAttributeOffsets(const DWARFAbbreviationDeclaration *Abbrev, unsigned Idx,
2008 unsigned Offset, const DWARFUnit &Unit) {
2009 DataExtractor Data = Unit.getDebugInfoExtractor();
2011 for (unsigned i = 0; i < Idx; ++i)
2012 DWARFFormValue::skipValue(Abbrev->getFormByIndex(i), Data, &Offset, &Unit);
2014 uint32_t End = Offset;
2015 DWARFFormValue::skipValue(Abbrev->getFormByIndex(Idx), Data, &End, &Unit);
2017 return std::make_pair(Offset, End);
2020 /// \brief Check if a variable describing DIE should be kept.
2021 /// \returns updated TraversalFlags.
2022 unsigned DwarfLinker::shouldKeepVariableDIE(RelocationManager &RelocMgr,
2023 const DWARFDebugInfoEntryMinimal &DIE,
2025 CompileUnit::DIEInfo &MyInfo,
2027 const auto *Abbrev = DIE.getAbbreviationDeclarationPtr();
2029 // Global variables with constant value can always be kept.
2030 if (!(Flags & TF_InFunctionScope) &&
2031 Abbrev->findAttributeIndex(dwarf::DW_AT_const_value) != -1U) {
2032 MyInfo.InDebugMap = true;
2033 return Flags | TF_Keep;
2036 uint32_t LocationIdx = Abbrev->findAttributeIndex(dwarf::DW_AT_location);
2037 if (LocationIdx == -1U)
2040 uint32_t Offset = DIE.getOffset() + getULEB128Size(Abbrev->getCode());
2041 const DWARFUnit &OrigUnit = Unit.getOrigUnit();
2042 uint32_t LocationOffset, LocationEndOffset;
2043 std::tie(LocationOffset, LocationEndOffset) =
2044 getAttributeOffsets(Abbrev, LocationIdx, Offset, OrigUnit);
2046 // See if there is a relocation to a valid debug map entry inside
2047 // this variable's location. The order is important here. We want to
2048 // always check in the variable has a valid relocation, so that the
2049 // DIEInfo is filled. However, we don't want a static variable in a
2050 // function to force us to keep the enclosing function.
2051 if (!RelocMgr.hasValidRelocation(LocationOffset, LocationEndOffset, MyInfo) ||
2052 (Flags & TF_InFunctionScope))
2055 if (Options.Verbose)
2056 DIE.dump(outs(), const_cast<DWARFUnit *>(&OrigUnit), 0, 8 /* Indent */);
2058 return Flags | TF_Keep;
2061 /// \brief Check if a function describing DIE should be kept.
2062 /// \returns updated TraversalFlags.
2063 unsigned DwarfLinker::shouldKeepSubprogramDIE(
2064 RelocationManager &RelocMgr,
2065 const DWARFDebugInfoEntryMinimal &DIE, CompileUnit &Unit,
2066 CompileUnit::DIEInfo &MyInfo, unsigned Flags) {
2067 const auto *Abbrev = DIE.getAbbreviationDeclarationPtr();
2069 Flags |= TF_InFunctionScope;
2071 uint32_t LowPcIdx = Abbrev->findAttributeIndex(dwarf::DW_AT_low_pc);
2072 if (LowPcIdx == -1U)
2075 uint32_t Offset = DIE.getOffset() + getULEB128Size(Abbrev->getCode());
2076 const DWARFUnit &OrigUnit = Unit.getOrigUnit();
2077 uint32_t LowPcOffset, LowPcEndOffset;
2078 std::tie(LowPcOffset, LowPcEndOffset) =
2079 getAttributeOffsets(Abbrev, LowPcIdx, Offset, OrigUnit);
2082 DIE.getAttributeValueAsAddress(&OrigUnit, dwarf::DW_AT_low_pc, -1ULL);
2083 assert(LowPc != -1ULL && "low_pc attribute is not an address.");
2084 if (LowPc == -1ULL ||
2085 !RelocMgr.hasValidRelocation(LowPcOffset, LowPcEndOffset, MyInfo))
2088 if (Options.Verbose)
2089 DIE.dump(outs(), const_cast<DWARFUnit *>(&OrigUnit), 0, 8 /* Indent */);
2093 DWARFFormValue HighPcValue;
2094 if (!DIE.getAttributeValue(&OrigUnit, dwarf::DW_AT_high_pc, HighPcValue)) {
2095 reportWarning("Function without high_pc. Range will be discarded.\n",
2101 if (HighPcValue.isFormClass(DWARFFormValue::FC_Address)) {
2102 HighPc = *HighPcValue.getAsAddress(&OrigUnit);
2104 assert(HighPcValue.isFormClass(DWARFFormValue::FC_Constant));
2105 HighPc = LowPc + *HighPcValue.getAsUnsignedConstant();
2108 // Replace the debug map range with a more accurate one.
2109 Ranges[LowPc] = std::make_pair(HighPc, MyInfo.AddrAdjust);
2110 Unit.addFunctionRange(LowPc, HighPc, MyInfo.AddrAdjust);
2114 /// \brief Check if a DIE should be kept.
2115 /// \returns updated TraversalFlags.
2116 unsigned DwarfLinker::shouldKeepDIE(RelocationManager &RelocMgr,
2117 const DWARFDebugInfoEntryMinimal &DIE,
2119 CompileUnit::DIEInfo &MyInfo,
2121 switch (DIE.getTag()) {
2122 case dwarf::DW_TAG_constant:
2123 case dwarf::DW_TAG_variable:
2124 return shouldKeepVariableDIE(RelocMgr, DIE, Unit, MyInfo, Flags);
2125 case dwarf::DW_TAG_subprogram:
2126 return shouldKeepSubprogramDIE(RelocMgr, DIE, Unit, MyInfo, Flags);
2127 case dwarf::DW_TAG_module:
2128 case dwarf::DW_TAG_imported_module:
2129 case dwarf::DW_TAG_imported_declaration:
2130 case dwarf::DW_TAG_imported_unit:
2131 // We always want to keep these.
2132 return Flags | TF_Keep;
2138 /// \brief Mark the passed DIE as well as all the ones it depends on
2141 /// This function is called by lookForDIEsToKeep on DIEs that are
2142 /// newly discovered to be needed in the link. It recursively calls
2143 /// back to lookForDIEsToKeep while adding TF_DependencyWalk to the
2144 /// TraversalFlags to inform it that it's not doing the primary DIE
2146 void DwarfLinker::keepDIEAndDependencies(RelocationManager &RelocMgr,
2147 const DWARFDebugInfoEntryMinimal &Die,
2148 CompileUnit::DIEInfo &MyInfo,
2149 const DebugMapObject &DMO,
2150 CompileUnit &CU, bool UseODR) {
2151 const DWARFUnit &Unit = CU.getOrigUnit();
2154 // First mark all the parent chain as kept.
2155 unsigned AncestorIdx = MyInfo.ParentIdx;
2156 while (!CU.getInfo(AncestorIdx).Keep) {
2157 unsigned ODRFlag = UseODR ? TF_ODR : 0;
2158 lookForDIEsToKeep(RelocMgr, *Unit.getDIEAtIndex(AncestorIdx), DMO, CU,
2159 TF_ParentWalk | TF_Keep | TF_DependencyWalk | ODRFlag);
2160 AncestorIdx = CU.getInfo(AncestorIdx).ParentIdx;
2163 // Then we need to mark all the DIEs referenced by this DIE's
2164 // attributes as kept.
2165 DataExtractor Data = Unit.getDebugInfoExtractor();
2166 const auto *Abbrev = Die.getAbbreviationDeclarationPtr();
2167 uint32_t Offset = Die.getOffset() + getULEB128Size(Abbrev->getCode());
2169 // Mark all DIEs referenced through atttributes as kept.
2170 for (const auto &AttrSpec : Abbrev->attributes()) {
2171 DWARFFormValue Val(AttrSpec.Form);
2173 if (!Val.isFormClass(DWARFFormValue::FC_Reference)) {
2174 DWARFFormValue::skipValue(AttrSpec.Form, Data, &Offset, &Unit);
2178 Val.extractValue(Data, &Offset, &Unit);
2179 CompileUnit *ReferencedCU;
2180 if (const auto *RefDIE =
2181 resolveDIEReference(*this, MutableArrayRef<CompileUnit>(Units), Val,
2182 Unit, Die, ReferencedCU)) {
2183 uint32_t RefIdx = ReferencedCU->getOrigUnit().getDIEIndex(RefDIE);
2184 CompileUnit::DIEInfo &Info = ReferencedCU->getInfo(RefIdx);
2185 // If the referenced DIE has a DeclContext that has already been
2186 // emitted, then do not keep the one in this CU. We'll link to
2187 // the canonical DIE in cloneDieReferenceAttribute.
2188 // FIXME: compatibility with dsymutil-classic. UseODR shouldn't
2189 // be necessary and could be advantageously replaced by
2190 // ReferencedCU->hasODR() && CU.hasODR().
2191 // FIXME: compatibility with dsymutil-classic. There is no
2192 // reason not to unique ref_addr references.
2193 if (AttrSpec.Form != dwarf::DW_FORM_ref_addr && UseODR && Info.Ctxt &&
2194 Info.Ctxt != ReferencedCU->getInfo(Info.ParentIdx).Ctxt &&
2195 Info.Ctxt->getCanonicalDIEOffset() && isODRAttribute(AttrSpec.Attr))
2198 // Keep a module forward declaration if there is no definition.
2199 if (!(isODRAttribute(AttrSpec.Attr) && Info.Ctxt &&
2200 Info.Ctxt->getCanonicalDIEOffset()))
2203 unsigned ODRFlag = UseODR ? TF_ODR : 0;
2204 lookForDIEsToKeep(RelocMgr, *RefDIE, DMO, *ReferencedCU,
2205 TF_Keep | TF_DependencyWalk | ODRFlag);
2210 /// \brief Recursively walk the \p DIE tree and look for DIEs to
2211 /// keep. Store that information in \p CU's DIEInfo.
2213 /// This function is the entry point of the DIE selection
2214 /// algorithm. It is expected to walk the DIE tree in file order and
2215 /// (though the mediation of its helper) call hasValidRelocation() on
2216 /// each DIE that might be a 'root DIE' (See DwarfLinker class
2218 /// While walking the dependencies of root DIEs, this function is
2219 /// also called, but during these dependency walks the file order is
2220 /// not respected. The TF_DependencyWalk flag tells us which kind of
2221 /// traversal we are currently doing.
2222 void DwarfLinker::lookForDIEsToKeep(RelocationManager &RelocMgr,
2223 const DWARFDebugInfoEntryMinimal &Die,
2224 const DebugMapObject &DMO, CompileUnit &CU,
2226 unsigned Idx = CU.getOrigUnit().getDIEIndex(&Die);
2227 CompileUnit::DIEInfo &MyInfo = CU.getInfo(Idx);
2228 bool AlreadyKept = MyInfo.Keep;
2232 // If the Keep flag is set, we are marking a required DIE's
2233 // dependencies. If our target is already marked as kept, we're all
2235 if ((Flags & TF_DependencyWalk) && AlreadyKept)
2238 // We must not call shouldKeepDIE while called from keepDIEAndDependencies,
2239 // because it would screw up the relocation finding logic.
2240 if (!(Flags & TF_DependencyWalk))
2241 Flags = shouldKeepDIE(RelocMgr, Die, CU, MyInfo, Flags);
2243 // If it is a newly kept DIE mark it as well as all its dependencies as kept.
2244 if (!AlreadyKept && (Flags & TF_Keep)) {
2245 bool UseOdr = (Flags & TF_DependencyWalk) ? (Flags & TF_ODR) : CU.hasODR();
2246 keepDIEAndDependencies(RelocMgr, Die, MyInfo, DMO, CU, UseOdr);
2248 // The TF_ParentWalk flag tells us that we are currently walking up
2249 // the parent chain of a required DIE, and we don't want to mark all
2250 // the children of the parents as kept (consider for example a
2251 // DW_TAG_namespace node in the parent chain). There are however a
2252 // set of DIE types for which we want to ignore that directive and still
2253 // walk their children.
2254 if (dieNeedsChildrenToBeMeaningful(Die.getTag()))
2255 Flags &= ~TF_ParentWalk;
2257 if (!Die.hasChildren() || (Flags & TF_ParentWalk))
2260 for (auto *Child = Die.getFirstChild(); Child && !Child->isNULL();
2261 Child = Child->getSibling())
2262 lookForDIEsToKeep(RelocMgr, *Child, DMO, CU, Flags);
2265 /// \brief Assign an abbreviation numer to \p Abbrev.
2267 /// Our DIEs get freed after every DebugMapObject has been processed,
2268 /// thus the FoldingSet we use to unique DIEAbbrevs cannot refer to
2269 /// the instances hold by the DIEs. When we encounter an abbreviation
2270 /// that we don't know, we create a permanent copy of it.
2271 void DwarfLinker::AssignAbbrev(DIEAbbrev &Abbrev) {
2272 // Check the set for priors.
2273 FoldingSetNodeID ID;
2276 DIEAbbrev *InSet = AbbreviationsSet.FindNodeOrInsertPos(ID, InsertToken);
2278 // If it's newly added.
2280 // Assign existing abbreviation number.
2281 Abbrev.setNumber(InSet->getNumber());
2283 // Add to abbreviation list.
2284 Abbreviations.push_back(
2285 new DIEAbbrev(Abbrev.getTag(), Abbrev.hasChildren()));
2286 for (const auto &Attr : Abbrev.getData())
2287 Abbreviations.back()->AddAttribute(Attr.getAttribute(), Attr.getForm());
2288 AbbreviationsSet.InsertNode(Abbreviations.back(), InsertToken);
2289 // Assign the unique abbreviation number.
2290 Abbrev.setNumber(Abbreviations.size());
2291 Abbreviations.back()->setNumber(Abbreviations.size());
2295 unsigned DwarfLinker::DIECloner::cloneStringAttribute(DIE &Die,
2296 AttributeSpec AttrSpec,
2297 const DWARFFormValue &Val,
2298 const DWARFUnit &U) {
2299 // Switch everything to out of line strings.
2300 const char *String = *Val.getAsCString(&U);
2301 unsigned Offset = Linker.StringPool.getStringOffset(String);
2302 Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr), dwarf::DW_FORM_strp,
2303 DIEInteger(Offset));
2307 unsigned DwarfLinker::DIECloner::cloneDieReferenceAttribute(
2308 DIE &Die, const DWARFDebugInfoEntryMinimal &InputDIE,
2309 AttributeSpec AttrSpec, unsigned AttrSize, const DWARFFormValue &Val,
2310 CompileUnit &Unit) {
2311 const DWARFUnit &U = Unit.getOrigUnit();
2312 uint32_t Ref = *Val.getAsReference(&U);
2313 DIE *NewRefDie = nullptr;
2314 CompileUnit *RefUnit = nullptr;
2315 DeclContext *Ctxt = nullptr;
2317 const DWARFDebugInfoEntryMinimal *RefDie =
2318 resolveDIEReference(Linker, CompileUnits, Val, U, InputDIE, RefUnit);
2320 // If the referenced DIE is not found, drop the attribute.
2324 unsigned Idx = RefUnit->getOrigUnit().getDIEIndex(RefDie);
2325 CompileUnit::DIEInfo &RefInfo = RefUnit->getInfo(Idx);
2327 // If we already have emitted an equivalent DeclContext, just point
2329 if (isODRAttribute(AttrSpec.Attr)) {
2330 Ctxt = RefInfo.Ctxt;
2331 if (Ctxt && Ctxt->getCanonicalDIEOffset()) {
2332 DIEInteger Attr(Ctxt->getCanonicalDIEOffset());
2333 Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
2334 dwarf::DW_FORM_ref_addr, Attr);
2335 return getRefAddrSize(U);
2339 if (!RefInfo.Clone) {
2340 assert(Ref > InputDIE.getOffset());
2341 // We haven't cloned this DIE yet. Just create an empty one and
2342 // store it. It'll get really cloned when we process it.
2343 RefInfo.Clone = DIE::get(DIEAlloc, dwarf::Tag(RefDie->getTag()));
2345 NewRefDie = RefInfo.Clone;
2347 if (AttrSpec.Form == dwarf::DW_FORM_ref_addr ||
2348 (Unit.hasODR() && isODRAttribute(AttrSpec.Attr))) {
2349 // We cannot currently rely on a DIEEntry to emit ref_addr
2350 // references, because the implementation calls back to DwarfDebug
2351 // to find the unit offset. (We don't have a DwarfDebug)
2352 // FIXME: we should be able to design DIEEntry reliance on
2355 if (Ref < InputDIE.getOffset()) {
2356 // We must have already cloned that DIE.
2357 uint32_t NewRefOffset =
2358 RefUnit->getStartOffset() + NewRefDie->getOffset();
2359 Attr = NewRefOffset;
2360 Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
2361 dwarf::DW_FORM_ref_addr, DIEInteger(Attr));
2363 // A forward reference. Note and fixup later.
2365 Unit.noteForwardReference(
2366 NewRefDie, RefUnit, Ctxt,
2367 Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
2368 dwarf::DW_FORM_ref_addr, DIEInteger(Attr)));
2370 return getRefAddrSize(U);
2373 Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
2374 dwarf::Form(AttrSpec.Form), DIEEntry(*NewRefDie));
2378 unsigned DwarfLinker::DIECloner::cloneBlockAttribute(DIE &Die,
2379 AttributeSpec AttrSpec,
2380 const DWARFFormValue &Val,
2381 unsigned AttrSize) {
2384 DIELoc *Loc = nullptr;
2385 DIEBlock *Block = nullptr;
2386 // Just copy the block data over.
2387 if (AttrSpec.Form == dwarf::DW_FORM_exprloc) {
2388 Loc = new (DIEAlloc) DIELoc;
2389 Linker.DIELocs.push_back(Loc);
2391 Block = new (DIEAlloc) DIEBlock;
2392 Linker.DIEBlocks.push_back(Block);
2394 Attr = Loc ? static_cast<DIEValueList *>(Loc)
2395 : static_cast<DIEValueList *>(Block);
2398 Value = DIEValue(dwarf::Attribute(AttrSpec.Attr),
2399 dwarf::Form(AttrSpec.Form), Loc);
2401 Value = DIEValue(dwarf::Attribute(AttrSpec.Attr),
2402 dwarf::Form(AttrSpec.Form), Block);
2403 ArrayRef<uint8_t> Bytes = *Val.getAsBlock();
2404 for (auto Byte : Bytes)
2405 Attr->addValue(DIEAlloc, static_cast<dwarf::Attribute>(0),
2406 dwarf::DW_FORM_data1, DIEInteger(Byte));
2407 // FIXME: If DIEBlock and DIELoc just reuses the Size field of
2408 // the DIE class, this if could be replaced by
2409 // Attr->setSize(Bytes.size()).
2410 if (Linker.Streamer) {
2411 auto *AsmPrinter = &Linker.Streamer->getAsmPrinter();
2413 Loc->ComputeSize(AsmPrinter);
2415 Block->ComputeSize(AsmPrinter);
2417 Die.addValue(DIEAlloc, Value);
2421 unsigned DwarfLinker::DIECloner::cloneAddressAttribute(
2422 DIE &Die, AttributeSpec AttrSpec, const DWARFFormValue &Val,
2423 const CompileUnit &Unit, AttributesInfo &Info) {
2424 uint64_t Addr = *Val.getAsAddress(&Unit.getOrigUnit());
2425 if (AttrSpec.Attr == dwarf::DW_AT_low_pc) {
2426 if (Die.getTag() == dwarf::DW_TAG_inlined_subroutine ||
2427 Die.getTag() == dwarf::DW_TAG_lexical_block)
2428 // The low_pc of a block or inline subroutine might get
2429 // relocated because it happens to match the low_pc of the
2430 // enclosing subprogram. To prevent issues with that, always use
2431 // the low_pc from the input DIE if relocations have been applied.
2432 Addr = (Info.OrigLowPc != UINT64_MAX ? Info.OrigLowPc : Addr) +
2434 else if (Die.getTag() == dwarf::DW_TAG_compile_unit) {
2435 Addr = Unit.getLowPc();
2436 if (Addr == UINT64_MAX)
2439 Info.HasLowPc = true;
2440 } else if (AttrSpec.Attr == dwarf::DW_AT_high_pc) {
2441 if (Die.getTag() == dwarf::DW_TAG_compile_unit) {
2442 if (uint64_t HighPc = Unit.getHighPc())
2447 // If we have a high_pc recorded for the input DIE, use
2448 // it. Otherwise (when no relocations where applied) just use the
2449 // one we just decoded.
2450 Addr = (Info.OrigHighPc ? Info.OrigHighPc : Addr) + Info.PCOffset;
2453 Die.addValue(DIEAlloc, static_cast<dwarf::Attribute>(AttrSpec.Attr),
2454 static_cast<dwarf::Form>(AttrSpec.Form), DIEInteger(Addr));
2455 return Unit.getOrigUnit().getAddressByteSize();
2458 unsigned DwarfLinker::DIECloner::cloneScalarAttribute(
2459 DIE &Die, const DWARFDebugInfoEntryMinimal &InputDIE, CompileUnit &Unit,
2460 AttributeSpec AttrSpec, const DWARFFormValue &Val, unsigned AttrSize,
2461 AttributesInfo &Info) {
2463 if (AttrSpec.Attr == dwarf::DW_AT_high_pc &&
2464 Die.getTag() == dwarf::DW_TAG_compile_unit) {
2465 if (Unit.getLowPc() == -1ULL)
2467 // Dwarf >= 4 high_pc is an size, not an address.
2468 Value = Unit.getHighPc() - Unit.getLowPc();
2469 } else if (AttrSpec.Form == dwarf::DW_FORM_sec_offset)
2470 Value = *Val.getAsSectionOffset();
2471 else if (AttrSpec.Form == dwarf::DW_FORM_sdata)
2472 Value = *Val.getAsSignedConstant();
2473 else if (auto OptionalValue = Val.getAsUnsignedConstant())
2474 Value = *OptionalValue;
2476 Linker.reportWarning(
2477 "Unsupported scalar attribute form. Dropping attribute.",
2478 &Unit.getOrigUnit(), &InputDIE);
2481 PatchLocation Patch =
2482 Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
2483 dwarf::Form(AttrSpec.Form), DIEInteger(Value));
2484 if (AttrSpec.Attr == dwarf::DW_AT_ranges)
2485 Unit.noteRangeAttribute(Die, Patch);
2487 // A more generic way to check for location attributes would be
2488 // nice, but it's very unlikely that any other attribute needs a
2490 else if (AttrSpec.Attr == dwarf::DW_AT_location ||
2491 AttrSpec.Attr == dwarf::DW_AT_frame_base)
2492 Unit.noteLocationAttribute(Patch, Info.PCOffset);
2493 else if (AttrSpec.Attr == dwarf::DW_AT_declaration && Value)
2494 Info.IsDeclaration = true;
2499 /// \brief Clone \p InputDIE's attribute described by \p AttrSpec with
2500 /// value \p Val, and add it to \p Die.
2501 /// \returns the size of the cloned attribute.
2502 unsigned DwarfLinker::DIECloner::cloneAttribute(
2503 DIE &Die, const DWARFDebugInfoEntryMinimal &InputDIE, CompileUnit &Unit,
2504 const DWARFFormValue &Val, const AttributeSpec AttrSpec, unsigned AttrSize,
2505 AttributesInfo &Info) {
2506 const DWARFUnit &U = Unit.getOrigUnit();
2508 switch (AttrSpec.Form) {
2509 case dwarf::DW_FORM_strp:
2510 case dwarf::DW_FORM_string:
2511 return cloneStringAttribute(Die, AttrSpec, Val, U);
2512 case dwarf::DW_FORM_ref_addr:
2513 case dwarf::DW_FORM_ref1:
2514 case dwarf::DW_FORM_ref2:
2515 case dwarf::DW_FORM_ref4:
2516 case dwarf::DW_FORM_ref8:
2517 return cloneDieReferenceAttribute(Die, InputDIE, AttrSpec, AttrSize, Val,
2519 case dwarf::DW_FORM_block:
2520 case dwarf::DW_FORM_block1:
2521 case dwarf::DW_FORM_block2:
2522 case dwarf::DW_FORM_block4:
2523 case dwarf::DW_FORM_exprloc:
2524 return cloneBlockAttribute(Die, AttrSpec, Val, AttrSize);
2525 case dwarf::DW_FORM_addr:
2526 return cloneAddressAttribute(Die, AttrSpec, Val, Unit, Info);
2527 case dwarf::DW_FORM_data1:
2528 case dwarf::DW_FORM_data2:
2529 case dwarf::DW_FORM_data4:
2530 case dwarf::DW_FORM_data8:
2531 case dwarf::DW_FORM_udata:
2532 case dwarf::DW_FORM_sdata:
2533 case dwarf::DW_FORM_sec_offset:
2534 case dwarf::DW_FORM_flag:
2535 case dwarf::DW_FORM_flag_present:
2536 return cloneScalarAttribute(Die, InputDIE, Unit, AttrSpec, Val, AttrSize,
2539 Linker.reportWarning(
2540 "Unsupported attribute form in cloneAttribute. Dropping.", &U,
2547 /// \brief Apply the valid relocations found by findValidRelocs() to
2548 /// the buffer \p Data, taking into account that Data is at \p BaseOffset
2549 /// in the debug_info section.
2551 /// Like for findValidRelocs(), this function must be called with
2552 /// monotonic \p BaseOffset values.
2554 /// \returns wether any reloc has been applied.
2555 bool DwarfLinker::RelocationManager::
2556 applyValidRelocs(MutableArrayRef<char> Data, uint32_t BaseOffset,
2557 bool isLittleEndian) {
2558 assert((NextValidReloc == 0 ||
2559 BaseOffset > ValidRelocs[NextValidReloc - 1].Offset) &&
2560 "BaseOffset should only be increasing.");
2561 if (NextValidReloc >= ValidRelocs.size())
2564 // Skip relocs that haven't been applied.
2565 while (NextValidReloc < ValidRelocs.size() &&
2566 ValidRelocs[NextValidReloc].Offset < BaseOffset)
2569 bool Applied = false;
2570 uint64_t EndOffset = BaseOffset + Data.size();
2571 while (NextValidReloc < ValidRelocs.size() &&
2572 ValidRelocs[NextValidReloc].Offset >= BaseOffset &&
2573 ValidRelocs[NextValidReloc].Offset < EndOffset) {
2574 const auto &ValidReloc = ValidRelocs[NextValidReloc++];
2575 assert(ValidReloc.Offset - BaseOffset < Data.size());
2576 assert(ValidReloc.Offset - BaseOffset + ValidReloc.Size <= Data.size());
2578 uint64_t Value = ValidReloc.Mapping->getValue().BinaryAddress;
2579 Value += ValidReloc.Addend;
2580 for (unsigned i = 0; i != ValidReloc.Size; ++i) {
2581 unsigned Index = isLittleEndian ? i : (ValidReloc.Size - i - 1);
2582 Buf[i] = uint8_t(Value >> (Index * 8));
2584 assert(ValidReloc.Size <= sizeof(Buf));
2585 memcpy(&Data[ValidReloc.Offset - BaseOffset], Buf, ValidReloc.Size);
2592 static bool isTypeTag(uint16_t Tag) {
2594 case dwarf::DW_TAG_array_type:
2595 case dwarf::DW_TAG_class_type:
2596 case dwarf::DW_TAG_enumeration_type:
2597 case dwarf::DW_TAG_pointer_type:
2598 case dwarf::DW_TAG_reference_type:
2599 case dwarf::DW_TAG_string_type:
2600 case dwarf::DW_TAG_structure_type:
2601 case dwarf::DW_TAG_subroutine_type:
2602 case dwarf::DW_TAG_typedef:
2603 case dwarf::DW_TAG_union_type:
2604 case dwarf::DW_TAG_ptr_to_member_type:
2605 case dwarf::DW_TAG_set_type:
2606 case dwarf::DW_TAG_subrange_type:
2607 case dwarf::DW_TAG_base_type:
2608 case dwarf::DW_TAG_const_type:
2609 case dwarf::DW_TAG_constant:
2610 case dwarf::DW_TAG_file_type:
2611 case dwarf::DW_TAG_namelist:
2612 case dwarf::DW_TAG_packed_type:
2613 case dwarf::DW_TAG_volatile_type:
2614 case dwarf::DW_TAG_restrict_type:
2615 case dwarf::DW_TAG_interface_type:
2616 case dwarf::DW_TAG_unspecified_type:
2617 case dwarf::DW_TAG_shared_type:
2626 shouldSkipAttribute(DWARFAbbreviationDeclaration::AttributeSpec AttrSpec,
2627 uint16_t Tag, bool InDebugMap, bool SkipPC,
2628 bool InFunctionScope) {
2629 switch (AttrSpec.Attr) {
2632 case dwarf::DW_AT_low_pc:
2633 case dwarf::DW_AT_high_pc:
2634 case dwarf::DW_AT_ranges:
2636 case dwarf::DW_AT_location:
2637 case dwarf::DW_AT_frame_base:
2638 // FIXME: for some reason dsymutil-classic keeps the location
2639 // attributes when they are of block type (ie. not location
2640 // lists). This is totally wrong for globals where we will keep a
2641 // wrong address. It is mostly harmless for locals, but there is
2642 // no point in keeping these anyway when the function wasn't linked.
2643 return (SkipPC || (!InFunctionScope && Tag == dwarf::DW_TAG_variable &&
2645 !DWARFFormValue(AttrSpec.Form).isFormClass(DWARFFormValue::FC_Block);
2649 DIE *DwarfLinker::DIECloner::cloneDIE(
2650 const DWARFDebugInfoEntryMinimal &InputDIE, CompileUnit &Unit,
2651 int64_t PCOffset, uint32_t OutOffset, unsigned Flags) {
2652 DWARFUnit &U = Unit.getOrigUnit();
2653 unsigned Idx = U.getDIEIndex(&InputDIE);
2654 CompileUnit::DIEInfo &Info = Unit.getInfo(Idx);
2656 // Should the DIE appear in the output?
2657 if (!Unit.getInfo(Idx).Keep)
2660 uint32_t Offset = InputDIE.getOffset();
2661 // The DIE might have been already created by a forward reference
2662 // (see cloneDieReferenceAttribute()).
2663 DIE *Die = Info.Clone;
2665 Die = Info.Clone = DIE::get(DIEAlloc, dwarf::Tag(InputDIE.getTag()));
2666 assert(Die->getTag() == InputDIE.getTag());
2667 Die->setOffset(OutOffset);
2668 if ((Unit.hasODR() || Unit.isClangModule()) &&
2669 Die->getTag() != dwarf::DW_TAG_namespace && Info.Ctxt &&
2670 Info.Ctxt != Unit.getInfo(Info.ParentIdx).Ctxt &&
2671 !Info.Ctxt->getCanonicalDIEOffset()) {
2672 // We are about to emit a DIE that is the root of its own valid
2673 // DeclContext tree. Make the current offset the canonical offset
2674 // for this context.
2675 Info.Ctxt->setCanonicalDIEOffset(OutOffset + Unit.getStartOffset());
2678 // Extract and clone every attribute.
2679 DataExtractor Data = U.getDebugInfoExtractor();
2680 // Point to the next DIE (generally there is always at least a NULL
2681 // entry after the current one). If this is a lone
2682 // DW_TAG_compile_unit without any children, point to the next unit.
2683 uint32_t NextOffset =
2684 (Idx + 1 < U.getNumDIEs())
2685 ? U.getDIEAtIndex(Idx + 1)->getOffset()
2686 : U.getNextUnitOffset();
2687 AttributesInfo AttrInfo;
2689 // We could copy the data only if we need to aply a relocation to
2690 // it. After testing, it seems there is no performance downside to
2691 // doing the copy unconditionally, and it makes the code simpler.
2692 SmallString<40> DIECopy(Data.getData().substr(Offset, NextOffset - Offset));
2693 Data = DataExtractor(DIECopy, Data.isLittleEndian(), Data.getAddressSize());
2694 // Modify the copy with relocated addresses.
2695 if (RelocMgr.applyValidRelocs(DIECopy, Offset, Data.isLittleEndian())) {
2696 // If we applied relocations, we store the value of high_pc that was
2697 // potentially stored in the input DIE. If high_pc is an address
2698 // (Dwarf version == 2), then it might have been relocated to a
2699 // totally unrelated value (because the end address in the object
2700 // file might be start address of another function which got moved
2701 // independantly by the linker). The computation of the actual
2702 // high_pc value is done in cloneAddressAttribute().
2703 AttrInfo.OrigHighPc =
2704 InputDIE.getAttributeValueAsAddress(&U, dwarf::DW_AT_high_pc, 0);
2705 // Also store the low_pc. It might get relocated in an
2706 // inline_subprogram that happens at the beginning of its
2707 // inlining function.
2708 AttrInfo.OrigLowPc =
2709 InputDIE.getAttributeValueAsAddress(&U, dwarf::DW_AT_low_pc, UINT64_MAX);
2712 // Reset the Offset to 0 as we will be working on the local copy of
2716 const auto *Abbrev = InputDIE.getAbbreviationDeclarationPtr();
2717 Offset += getULEB128Size(Abbrev->getCode());
2719 // We are entering a subprogram. Get and propagate the PCOffset.
2720 if (Die->getTag() == dwarf::DW_TAG_subprogram)
2721 PCOffset = Info.AddrAdjust;
2722 AttrInfo.PCOffset = PCOffset;
2724 if (Abbrev->getTag() == dwarf::DW_TAG_subprogram) {
2725 Flags |= TF_InFunctionScope;
2726 if (!Info.InDebugMap)
2730 bool Copied = false;
2731 for (const auto &AttrSpec : Abbrev->attributes()) {
2732 if (shouldSkipAttribute(AttrSpec, Die->getTag(), Info.InDebugMap,
2733 Flags & TF_SkipPC, Flags & TF_InFunctionScope)) {
2734 DWARFFormValue::skipValue(AttrSpec.Form, Data, &Offset, &U);
2735 // FIXME: dsymutil-classic keeps the old abbreviation around
2736 // even if it's not used. We can remove this (and the copyAbbrev
2737 // helper) as soon as bit-for-bit compatibility is not a goal anymore.
2739 copyAbbrev(*InputDIE.getAbbreviationDeclarationPtr(), Unit.hasODR());
2745 DWARFFormValue Val(AttrSpec.Form);
2746 uint32_t AttrSize = Offset;
2747 Val.extractValue(Data, &Offset, &U);
2748 AttrSize = Offset - AttrSize;
2751 cloneAttribute(*Die, InputDIE, Unit, Val, AttrSpec, AttrSize, AttrInfo);
2754 // Look for accelerator entries.
2755 uint16_t Tag = InputDIE.getTag();
2756 // FIXME: This is slightly wrong. An inline_subroutine without a
2757 // low_pc, but with AT_ranges might be interesting to get into the
2758 // accelerator tables too. For now stick with dsymutil's behavior.
2759 if ((Info.InDebugMap || AttrInfo.HasLowPc) &&
2760 Tag != dwarf::DW_TAG_compile_unit &&
2761 getDIENames(InputDIE, Unit.getOrigUnit(), AttrInfo)) {
2762 if (AttrInfo.MangledName && AttrInfo.MangledName != AttrInfo.Name)
2763 Unit.addNameAccelerator(Die, AttrInfo.MangledName,
2764 AttrInfo.MangledNameOffset,
2765 Tag == dwarf::DW_TAG_inlined_subroutine);
2767 Unit.addNameAccelerator(Die, AttrInfo.Name, AttrInfo.NameOffset,
2768 Tag == dwarf::DW_TAG_inlined_subroutine);
2769 } else if (isTypeTag(Tag) && !AttrInfo.IsDeclaration &&
2770 getDIENames(InputDIE, Unit.getOrigUnit(), AttrInfo)) {
2771 Unit.addTypeAccelerator(Die, AttrInfo.Name, AttrInfo.NameOffset);
2774 // Determine whether there are any children that we want to keep.
2775 bool HasChildren = false;
2776 for (auto *Child = InputDIE.getFirstChild(); Child && !Child->isNULL();
2777 Child = Child->getSibling()) {
2778 unsigned Idx = U.getDIEIndex(Child);
2779 if (Unit.getInfo(Idx).Keep) {
2785 DIEAbbrev NewAbbrev = Die->generateAbbrev();
2787 NewAbbrev.setChildrenFlag(dwarf::DW_CHILDREN_yes);
2788 // Assign a permanent abbrev number
2789 Linker.AssignAbbrev(NewAbbrev);
2790 Die->setAbbrevNumber(NewAbbrev.getNumber());
2792 // Add the size of the abbreviation number to the output offset.
2793 OutOffset += getULEB128Size(Die->getAbbrevNumber());
2797 Die->setSize(OutOffset - Die->getOffset());
2801 // Recursively clone children.
2802 for (auto *Child = InputDIE.getFirstChild(); Child && !Child->isNULL();
2803 Child = Child->getSibling()) {
2804 if (DIE *Clone = cloneDIE(*Child, Unit, PCOffset, OutOffset, Flags)) {
2805 Die->addChild(Clone);
2806 OutOffset = Clone->getOffset() + Clone->getSize();
2810 // Account for the end of children marker.
2811 OutOffset += sizeof(int8_t);
2813 Die->setSize(OutOffset - Die->getOffset());
2817 /// \brief Patch the input object file relevant debug_ranges entries
2818 /// and emit them in the output file. Update the relevant attributes
2819 /// to point at the new entries.
2820 void DwarfLinker::patchRangesForUnit(const CompileUnit &Unit,
2821 DWARFContext &OrigDwarf) const {
2822 DWARFDebugRangeList RangeList;
2823 const auto &FunctionRanges = Unit.getFunctionRanges();
2824 unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
2825 DataExtractor RangeExtractor(OrigDwarf.getRangeSection(),
2826 OrigDwarf.isLittleEndian(), AddressSize);
2827 auto InvalidRange = FunctionRanges.end(), CurrRange = InvalidRange;
2828 DWARFUnit &OrigUnit = Unit.getOrigUnit();
2829 const auto *OrigUnitDie = OrigUnit.getUnitDIE(false);
2830 uint64_t OrigLowPc = OrigUnitDie->getAttributeValueAsAddress(
2831 &OrigUnit, dwarf::DW_AT_low_pc, -1ULL);
2832 // Ranges addresses are based on the unit's low_pc. Compute the
2833 // offset we need to apply to adapt to the the new unit's low_pc.
2834 int64_t UnitPcOffset = 0;
2835 if (OrigLowPc != -1ULL)
2836 UnitPcOffset = int64_t(OrigLowPc) - Unit.getLowPc();
2838 for (const auto &RangeAttribute : Unit.getRangesAttributes()) {
2839 uint32_t Offset = RangeAttribute.get();
2840 RangeAttribute.set(Streamer->getRangesSectionSize());
2841 RangeList.extract(RangeExtractor, &Offset);
2842 const auto &Entries = RangeList.getEntries();
2843 if (!Entries.empty()) {
2844 const DWARFDebugRangeList::RangeListEntry &First = Entries.front();
2846 if (CurrRange == InvalidRange ||
2847 First.StartAddress + OrigLowPc < CurrRange.start() ||
2848 First.StartAddress + OrigLowPc >= CurrRange.stop()) {
2849 CurrRange = FunctionRanges.find(First.StartAddress + OrigLowPc);
2850 if (CurrRange == InvalidRange ||
2851 CurrRange.start() > First.StartAddress + OrigLowPc) {
2852 reportWarning("no mapping for range.");
2858 Streamer->emitRangesEntries(UnitPcOffset, OrigLowPc, CurrRange, Entries,
2863 /// \brief Generate the debug_aranges entries for \p Unit and if the
2864 /// unit has a DW_AT_ranges attribute, also emit the debug_ranges
2865 /// contribution for this attribute.
2866 /// FIXME: this could actually be done right in patchRangesForUnit,
2867 /// but for the sake of initial bit-for-bit compatibility with legacy
2868 /// dsymutil, we have to do it in a delayed pass.
2869 void DwarfLinker::generateUnitRanges(CompileUnit &Unit) const {
2870 auto Attr = Unit.getUnitRangesAttribute();
2872 Attr->set(Streamer->getRangesSectionSize());
2873 Streamer->emitUnitRangesEntries(Unit, static_cast<bool>(Attr));
2876 /// \brief Insert the new line info sequence \p Seq into the current
2877 /// set of already linked line info \p Rows.
2878 static void insertLineSequence(std::vector<DWARFDebugLine::Row> &Seq,
2879 std::vector<DWARFDebugLine::Row> &Rows) {
2883 if (!Rows.empty() && Rows.back().Address < Seq.front().Address) {
2884 Rows.insert(Rows.end(), Seq.begin(), Seq.end());
2889 auto InsertPoint = std::lower_bound(
2890 Rows.begin(), Rows.end(), Seq.front(),
2891 [](const DWARFDebugLine::Row &LHS, const DWARFDebugLine::Row &RHS) {
2892 return LHS.Address < RHS.Address;
2895 // FIXME: this only removes the unneeded end_sequence if the
2896 // sequences have been inserted in order. using a global sort like
2897 // described in patchLineTableForUnit() and delaying the end_sequene
2898 // elimination to emitLineTableForUnit() we can get rid of all of them.
2899 if (InsertPoint != Rows.end() &&
2900 InsertPoint->Address == Seq.front().Address && InsertPoint->EndSequence) {
2901 *InsertPoint = Seq.front();
2902 Rows.insert(InsertPoint + 1, Seq.begin() + 1, Seq.end());
2904 Rows.insert(InsertPoint, Seq.begin(), Seq.end());
2910 static void patchStmtList(DIE &Die, DIEInteger Offset) {
2911 for (auto &V : Die.values())
2912 if (V.getAttribute() == dwarf::DW_AT_stmt_list) {
2913 V = DIEValue(V.getAttribute(), V.getForm(), Offset);
2917 llvm_unreachable("Didn't find DW_AT_stmt_list in cloned DIE!");
2920 /// \brief Extract the line table for \p Unit from \p OrigDwarf, and
2921 /// recreate a relocated version of these for the address ranges that
2922 /// are present in the binary.
2923 void DwarfLinker::patchLineTableForUnit(CompileUnit &Unit,
2924 DWARFContext &OrigDwarf) {
2925 const DWARFDebugInfoEntryMinimal *CUDie = Unit.getOrigUnit().getUnitDIE();
2926 uint64_t StmtList = CUDie->getAttributeValueAsSectionOffset(
2927 &Unit.getOrigUnit(), dwarf::DW_AT_stmt_list, -1ULL);
2928 if (StmtList == -1ULL)
2931 // Update the cloned DW_AT_stmt_list with the correct debug_line offset.
2932 if (auto *OutputDIE = Unit.getOutputUnitDIE())
2933 patchStmtList(*OutputDIE, DIEInteger(Streamer->getLineSectionSize()));
2935 // Parse the original line info for the unit.
2936 DWARFDebugLine::LineTable LineTable;
2937 uint32_t StmtOffset = StmtList;
2938 StringRef LineData = OrigDwarf.getLineSection().Data;
2939 DataExtractor LineExtractor(LineData, OrigDwarf.isLittleEndian(),
2940 Unit.getOrigUnit().getAddressByteSize());
2941 LineTable.parse(LineExtractor, &OrigDwarf.getLineSection().Relocs,
2944 // This vector is the output line table.
2945 std::vector<DWARFDebugLine::Row> NewRows;
2946 NewRows.reserve(LineTable.Rows.size());
2948 // Current sequence of rows being extracted, before being inserted
2950 std::vector<DWARFDebugLine::Row> Seq;
2951 const auto &FunctionRanges = Unit.getFunctionRanges();
2952 auto InvalidRange = FunctionRanges.end(), CurrRange = InvalidRange;
2954 // FIXME: This logic is meant to generate exactly the same output as
2955 // Darwin's classic dsynutil. There is a nicer way to implement this
2956 // by simply putting all the relocated line info in NewRows and simply
2957 // sorting NewRows before passing it to emitLineTableForUnit. This
2958 // should be correct as sequences for a function should stay
2959 // together in the sorted output. There are a few corner cases that
2960 // look suspicious though, and that required to implement the logic
2961 // this way. Revisit that once initial validation is finished.
2963 // Iterate over the object file line info and extract the sequences
2964 // that correspond to linked functions.
2965 for (auto &Row : LineTable.Rows) {
2966 // Check wether we stepped out of the range. The range is
2967 // half-open, but consider accept the end address of the range if
2968 // it is marked as end_sequence in the input (because in that
2969 // case, the relocation offset is accurate and that entry won't
2970 // serve as the start of another function).
2971 if (CurrRange == InvalidRange || Row.Address < CurrRange.start() ||
2972 Row.Address > CurrRange.stop() ||
2973 (Row.Address == CurrRange.stop() && !Row.EndSequence)) {
2974 // We just stepped out of a known range. Insert a end_sequence
2975 // corresponding to the end of the range.
2976 uint64_t StopAddress = CurrRange != InvalidRange
2977 ? CurrRange.stop() + CurrRange.value()
2979 CurrRange = FunctionRanges.find(Row.Address);
2980 bool CurrRangeValid =
2981 CurrRange != InvalidRange && CurrRange.start() <= Row.Address;
2982 if (!CurrRangeValid) {
2983 CurrRange = InvalidRange;
2984 if (StopAddress != -1ULL) {
2985 // Try harder by looking in the DebugMapObject function
2986 // ranges map. There are corner cases where this finds a
2987 // valid entry. It's unclear if this is right or wrong, but
2988 // for now do as dsymutil.
2989 // FIXME: Understand exactly what cases this addresses and
2990 // potentially remove it along with the Ranges map.
2991 auto Range = Ranges.lower_bound(Row.Address);
2992 if (Range != Ranges.begin() && Range != Ranges.end())
2995 if (Range != Ranges.end() && Range->first <= Row.Address &&
2996 Range->second.first >= Row.Address) {
2997 StopAddress = Row.Address + Range->second.second;
3001 if (StopAddress != -1ULL && !Seq.empty()) {
3002 // Insert end sequence row with the computed end address, but
3003 // the same line as the previous one.
3004 auto NextLine = Seq.back();
3005 NextLine.Address = StopAddress;
3006 NextLine.EndSequence = 1;
3007 NextLine.PrologueEnd = 0;
3008 NextLine.BasicBlock = 0;
3009 NextLine.EpilogueBegin = 0;
3010 Seq.push_back(NextLine);
3011 insertLineSequence(Seq, NewRows);
3014 if (!CurrRangeValid)
3018 // Ignore empty sequences.
3019 if (Row.EndSequence && Seq.empty())
3022 // Relocate row address and add it to the current sequence.
3023 Row.Address += CurrRange.value();
3024 Seq.emplace_back(Row);
3026 if (Row.EndSequence)
3027 insertLineSequence(Seq, NewRows);
3030 // Finished extracting, now emit the line tables.
3031 uint32_t PrologueEnd = StmtList + 10 + LineTable.Prologue.PrologueLength;
3032 // FIXME: LLVM hardcodes it's prologue values. We just copy the
3033 // prologue over and that works because we act as both producer and
3034 // consumer. It would be nicer to have a real configurable line
3036 if (LineTable.Prologue.Version != 2 ||
3037 LineTable.Prologue.DefaultIsStmt != DWARF2_LINE_DEFAULT_IS_STMT ||
3038 LineTable.Prologue.OpcodeBase > 13)
3039 reportWarning("line table paramters mismatch. Cannot emit.");
3041 MCDwarfLineTableParams Params;
3042 Params.DWARF2LineOpcodeBase = LineTable.Prologue.OpcodeBase;
3043 Params.DWARF2LineBase = LineTable.Prologue.LineBase;
3044 Params.DWARF2LineRange = LineTable.Prologue.LineRange;
3045 Streamer->emitLineTableForUnit(Params,
3046 LineData.slice(StmtList + 4, PrologueEnd),
3047 LineTable.Prologue.MinInstLength, NewRows,
3048 Unit.getOrigUnit().getAddressByteSize());
3052 void DwarfLinker::emitAcceleratorEntriesForUnit(CompileUnit &Unit) {
3053 Streamer->emitPubNamesForUnit(Unit);
3054 Streamer->emitPubTypesForUnit(Unit);
3057 /// \brief Read the frame info stored in the object, and emit the
3058 /// patched frame descriptions for the linked binary.
3060 /// This is actually pretty easy as the data of the CIEs and FDEs can
3061 /// be considered as black boxes and moved as is. The only thing to do
3062 /// is to patch the addresses in the headers.
3063 void DwarfLinker::patchFrameInfoForObject(const DebugMapObject &DMO,
3064 DWARFContext &OrigDwarf,
3065 unsigned AddrSize) {
3066 StringRef FrameData = OrigDwarf.getDebugFrameSection();
3067 if (FrameData.empty())
3070 DataExtractor Data(FrameData, OrigDwarf.isLittleEndian(), 0);
3071 uint32_t InputOffset = 0;
3073 // Store the data of the CIEs defined in this object, keyed by their
3075 DenseMap<uint32_t, StringRef> LocalCIES;
3077 while (Data.isValidOffset(InputOffset)) {
3078 uint32_t EntryOffset = InputOffset;
3079 uint32_t InitialLength = Data.getU32(&InputOffset);
3080 if (InitialLength == 0xFFFFFFFF)
3081 return reportWarning("Dwarf64 bits no supported");
3083 uint32_t CIEId = Data.getU32(&InputOffset);
3084 if (CIEId == 0xFFFFFFFF) {
3085 // This is a CIE, store it.
3086 StringRef CIEData = FrameData.substr(EntryOffset, InitialLength + 4);
3087 LocalCIES[EntryOffset] = CIEData;
3088 // The -4 is to account for the CIEId we just read.
3089 InputOffset += InitialLength - 4;
3093 uint32_t Loc = Data.getUnsigned(&InputOffset, AddrSize);
3095 // Some compilers seem to emit frame info that doesn't start at
3096 // the function entry point, thus we can't just lookup the address
3097 // in the debug map. Use the linker's range map to see if the FDE
3098 // describes something that we can relocate.
3099 auto Range = Ranges.upper_bound(Loc);
3100 if (Range != Ranges.begin())
3102 if (Range == Ranges.end() || Range->first > Loc ||
3103 Range->second.first <= Loc) {
3104 // The +4 is to account for the size of the InitialLength field itself.
3105 InputOffset = EntryOffset + InitialLength + 4;
3109 // This is an FDE, and we have a mapping.
3110 // Have we already emitted a corresponding CIE?
3111 StringRef CIEData = LocalCIES[CIEId];
3112 if (CIEData.empty())
3113 return reportWarning("Inconsistent debug_frame content. Dropping.");
3115 // Look if we already emitted a CIE that corresponds to the
3116 // referenced one (the CIE data is the key of that lookup).
3117 auto IteratorInserted = EmittedCIEs.insert(
3118 std::make_pair(CIEData, Streamer->getFrameSectionSize()));
3119 // If there is no CIE yet for this ID, emit it.
3120 if (IteratorInserted.second ||
3121 // FIXME: dsymutil-classic only caches the last used CIE for
3122 // reuse. Mimic that behavior for now. Just removing that
3123 // second half of the condition and the LastCIEOffset variable
3124 // makes the code DTRT.
3125 LastCIEOffset != IteratorInserted.first->getValue()) {
3126 LastCIEOffset = Streamer->getFrameSectionSize();
3127 IteratorInserted.first->getValue() = LastCIEOffset;
3128 Streamer->emitCIE(CIEData);
3131 // Emit the FDE with updated address and CIE pointer.
3132 // (4 + AddrSize) is the size of the CIEId + initial_location
3133 // fields that will get reconstructed by emitFDE().
3134 unsigned FDERemainingBytes = InitialLength - (4 + AddrSize);
3135 Streamer->emitFDE(IteratorInserted.first->getValue(), AddrSize,
3136 Loc + Range->second.second,
3137 FrameData.substr(InputOffset, FDERemainingBytes));
3138 InputOffset += FDERemainingBytes;
3142 void DwarfLinker::DIECloner::copyAbbrev(
3143 const DWARFAbbreviationDeclaration &Abbrev, bool hasODR) {
3144 DIEAbbrev Copy(dwarf::Tag(Abbrev.getTag()),
3145 dwarf::Form(Abbrev.hasChildren()));
3147 for (const auto &Attr : Abbrev.attributes()) {
3148 uint16_t Form = Attr.Form;
3149 if (hasODR && isODRAttribute(Attr.Attr))
3150 Form = dwarf::DW_FORM_ref_addr;
3151 Copy.AddAttribute(dwarf::Attribute(Attr.Attr), dwarf::Form(Form));
3154 Linker.AssignAbbrev(Copy);
3157 static uint64_t getDwoId(const DWARFDebugInfoEntryMinimal &CUDie,
3158 const DWARFUnit &Unit) {
3160 CUDie.getAttributeValueAsUnsignedConstant(&Unit, dwarf::DW_AT_dwo_id, 0);
3162 DwoId = CUDie.getAttributeValueAsUnsignedConstant(&Unit,
3163 dwarf::DW_AT_GNU_dwo_id, 0);
3167 bool DwarfLinker::registerModuleReference(
3168 const DWARFDebugInfoEntryMinimal &CUDie, const DWARFUnit &Unit,
3169 DebugMap &ModuleMap, unsigned Indent) {
3170 std::string PCMfile =
3171 CUDie.getAttributeValueAsString(&Unit, dwarf::DW_AT_dwo_name, "");
3172 if (PCMfile.empty())
3174 CUDie.getAttributeValueAsString(&Unit, dwarf::DW_AT_GNU_dwo_name, "");
3175 if (PCMfile.empty())
3178 // Clang module DWARF skeleton CUs abuse this for the path to the module.
3179 std::string PCMpath =
3180 CUDie.getAttributeValueAsString(&Unit, dwarf::DW_AT_comp_dir, "");
3181 uint64_t DwoId = getDwoId(CUDie, Unit);
3184 CUDie.getAttributeValueAsString(&Unit, dwarf::DW_AT_name, "");
3186 reportWarning("Anonymous module skeleton CU for " + PCMfile);
3190 if (Options.Verbose) {
3191 outs().indent(Indent);
3192 outs() << "Found clang module reference " << PCMfile;
3195 auto Cached = ClangModules.find(PCMfile);
3196 if (Cached != ClangModules.end()) {
3197 if (Cached->second != DwoId)
3198 reportWarning(Twine("hash mismatch: this object file was built against a "
3199 "different version of the module ") + PCMfile);
3200 if (Options.Verbose)
3201 outs() << " [cached].\n";
3204 if (Options.Verbose)
3207 // Cyclic dependencies are disallowed by Clang, but we still
3208 // shouldn't run into an infinite loop, so mark it as processed now.
3209 ClangModules.insert({PCMfile, DwoId});
3210 loadClangModule(PCMfile, PCMpath, Name, DwoId, ModuleMap, Indent + 2);
3214 ErrorOr<const object::ObjectFile &>
3215 DwarfLinker::loadObject(BinaryHolder &BinaryHolder, DebugMapObject &Obj,
3216 const DebugMap &Map) {
3218 BinaryHolder.GetObjectFiles(Obj.getObjectFilename(), Obj.getTimestamp());
3219 if (std::error_code EC = ErrOrObjs.getError()) {
3220 reportWarning(Twine(Obj.getObjectFilename()) + ": " + EC.message());
3223 auto ErrOrObj = BinaryHolder.Get(Map.getTriple());
3224 if (std::error_code EC = ErrOrObj.getError())
3225 reportWarning(Twine(Obj.getObjectFilename()) + ": " + EC.message());
3229 void DwarfLinker::loadClangModule(StringRef Filename, StringRef ModulePath,
3230 StringRef ModuleName, uint64_t DwoId,
3231 DebugMap &ModuleMap, unsigned Indent) {
3232 SmallString<80> Path(Options.PrependPath);
3233 if (sys::path::is_relative(Filename))
3234 sys::path::append(Path, ModulePath, Filename);
3236 sys::path::append(Path, Filename);
3237 BinaryHolder ObjHolder(Options.Verbose);
3239 ModuleMap.addDebugMapObject(Path, sys::TimeValue::PosixZeroTime());
3240 auto ErrOrObj = loadObject(ObjHolder, Obj, ModuleMap);
3242 ClangModules.erase(ClangModules.find(Filename));
3246 std::unique_ptr<CompileUnit> Unit;
3248 // Setup access to the debug info.
3249 DWARFContextInMemory DwarfContext(*ErrOrObj);
3250 RelocationManager RelocMgr(*this);
3251 for (const auto &CU : DwarfContext.compile_units()) {
3252 auto *CUDie = CU->getUnitDIE(false);
3253 // Recursively get all modules imported by this one.
3254 if (!registerModuleReference(*CUDie, *CU, ModuleMap, Indent)) {
3256 errs() << Filename << ": Clang modules are expected to have exactly"
3257 << " 1 compile unit.\n";
3260 if (getDwoId(*CUDie, *CU) != DwoId)
3262 Twine("hash mismatch: this object file was built against a "
3263 "different version of the module ") + Filename);
3266 Unit = llvm::make_unique<CompileUnit>(*CU, UnitID++, !Options.NoODR,
3268 Unit->setHasInterestingContent();
3269 analyzeContextInfo(CUDie, 0, *Unit, &ODRContexts.getRoot(), StringPool,
3272 Unit->markEverythingAsKept();
3275 if (Options.Verbose) {
3276 outs().indent(Indent);
3277 outs() << "cloning .debug_info from " << Filename << "\n";
3280 DIECloner(*this, RelocMgr, DIEAlloc, MutableArrayRef<CompileUnit>(*Unit),
3282 .cloneAllCompileUnits(DwarfContext);
3285 void DwarfLinker::DIECloner::cloneAllCompileUnits(
3286 DWARFContextInMemory &DwarfContext) {
3287 if (!Linker.Streamer)
3290 for (auto &CurrentUnit : CompileUnits) {
3291 const auto *InputDIE = CurrentUnit.getOrigUnit().getUnitDIE();
3292 CurrentUnit.setStartOffset(Linker.OutputDebugInfoSize);
3293 DIE *OutputDIE = cloneDIE(*InputDIE, CurrentUnit, 0 /* PC offset */,
3294 11 /* Unit Header size */, 0);
3295 CurrentUnit.setOutputUnitDIE(OutputDIE);
3296 Linker.OutputDebugInfoSize = CurrentUnit.computeNextUnitOffset();
3297 if (Linker.Options.NoOutput)
3299 // FIXME: for compatibility with the classic dsymutil, we emit
3300 // an empty line table for the unit, even if the unit doesn't
3301 // actually exist in the DIE tree.
3302 Linker.patchLineTableForUnit(CurrentUnit, DwarfContext);
3305 Linker.patchRangesForUnit(CurrentUnit, DwarfContext);
3306 Linker.Streamer->emitLocationsForUnit(CurrentUnit, DwarfContext);
3307 Linker.emitAcceleratorEntriesForUnit(CurrentUnit);
3310 if (Linker.Options.NoOutput)
3313 // Emit all the compile unit's debug information.
3314 for (auto &CurrentUnit : CompileUnits) {
3315 Linker.generateUnitRanges(CurrentUnit);
3316 CurrentUnit.fixupForwardReferences();
3317 Linker.Streamer->emitCompileUnitHeader(CurrentUnit);
3318 if (!CurrentUnit.getOutputUnitDIE())
3320 Linker.Streamer->emitDIE(*CurrentUnit.getOutputUnitDIE());
3324 bool DwarfLinker::link(const DebugMap &Map) {
3326 if (!createStreamer(Map.getTriple(), OutputFilename))
3329 // Size of the DIEs (and headers) generated for the linked output.
3330 OutputDebugInfoSize = 0;
3331 // A unique ID that identifies each compile unit.
3333 DebugMap ModuleMap(Map.getTriple(), Map.getBinaryPath());
3335 for (const auto &Obj : Map.objects()) {
3336 CurrentDebugObject = Obj.get();
3338 if (Options.Verbose)
3339 outs() << "DEBUG MAP OBJECT: " << Obj->getObjectFilename() << "\n";
3340 auto ErrOrObj = loadObject(BinHolder, *Obj, Map);
3344 // Look for relocations that correspond to debug map entries.
3345 RelocationManager RelocMgr(*this);
3346 if (!RelocMgr.findValidRelocsInDebugInfo(*ErrOrObj, *Obj)) {
3347 if (Options.Verbose)
3348 outs() << "No valid relocations found. Skipping.\n";
3352 // Setup access to the debug info.
3353 DWARFContextInMemory DwarfContext(*ErrOrObj);
3354 startDebugObject(DwarfContext, *Obj);
3356 // In a first phase, just read in the debug info and load all clang modules.
3357 for (const auto &CU : DwarfContext.compile_units()) {
3358 auto *CUDie = CU->getUnitDIE(false);
3359 if (Options.Verbose) {
3360 outs() << "Input compilation unit:";
3361 CUDie->dump(outs(), CU.get(), 0);
3364 if (!registerModuleReference(*CUDie, *CU, ModuleMap))
3365 Units.emplace_back(*CU, UnitID++, !Options.NoODR, "");
3368 // Now build the DIE parent links that we will use during the next phase.
3369 for (auto &CurrentUnit : Units)
3370 analyzeContextInfo(CurrentUnit.getOrigUnit().getUnitDIE(), 0, CurrentUnit,
3371 &ODRContexts.getRoot(), StringPool, ODRContexts);
3373 // Then mark all the DIEs that need to be present in the linked
3374 // output and collect some information about them. Note that this
3375 // loop can not be merged with the previous one becaue cross-cu
3376 // references require the ParentIdx to be setup for every CU in
3377 // the object file before calling this.
3378 for (auto &CurrentUnit : Units)
3379 lookForDIEsToKeep(RelocMgr, *CurrentUnit.getOrigUnit().getUnitDIE(), *Obj,
3382 // The calls to applyValidRelocs inside cloneDIE will walk the
3383 // reloc array again (in the same way findValidRelocsInDebugInfo()
3384 // did). We need to reset the NextValidReloc index to the beginning.
3385 RelocMgr.resetValidRelocs();
3386 if (RelocMgr.hasValidRelocs())
3387 DIECloner(*this, RelocMgr, DIEAlloc, Units, Options)
3388 .cloneAllCompileUnits(DwarfContext);
3389 if (!Options.NoOutput && !Units.empty())
3390 patchFrameInfoForObject(*Obj, DwarfContext,
3391 Units[0].getOrigUnit().getAddressByteSize());
3393 // Clean-up before starting working on the next object.
3397 // Emit everything that's global.
3398 if (!Options.NoOutput) {
3399 Streamer->emitAbbrevs(Abbreviations);
3400 Streamer->emitStrings(StringPool);
3403 return Options.NoOutput ? true : Streamer->finish(Map);
3407 /// \brief Get the offset of string \p S in the string table. This
3408 /// can insert a new element or return the offset of a preexisitng
3410 uint32_t NonRelocatableStringpool::getStringOffset(StringRef S) {
3411 if (S.empty() && !Strings.empty())
3414 std::pair<uint32_t, StringMapEntryBase *> Entry(0, nullptr);
3418 // A non-empty string can't be at offset 0, so if we have an entry
3419 // with a 0 offset, it must be a previously interned string.
3420 std::tie(It, Inserted) = Strings.insert(std::make_pair(S, Entry));
3421 if (Inserted || It->getValue().first == 0) {
3422 // Set offset and chain at the end of the entries list.
3423 It->getValue().first = CurrentEndOffset;
3424 CurrentEndOffset += S.size() + 1; // +1 for the '\0'.
3425 Last->getValue().second = &*It;
3428 return It->getValue().first;
3431 /// \brief Put \p S into the StringMap so that it gets permanent
3432 /// storage, but do not actually link it in the chain of elements
3433 /// that go into the output section. A latter call to
3434 /// getStringOffset() with the same string will chain it though.
3435 StringRef NonRelocatableStringpool::internString(StringRef S) {
3436 std::pair<uint32_t, StringMapEntryBase *> Entry(0, nullptr);
3437 auto InsertResult = Strings.insert(std::make_pair(S, Entry));
3438 return InsertResult.first->getKey();
3441 void warn(const Twine &Warning, const Twine &Context) {
3442 errs() << Twine("while processing ") + Context + ":\n";
3443 errs() << Twine("warning: ") + Warning + "\n";
3446 bool error(const Twine &Error, const Twine &Context) {
3447 errs() << Twine("while processing ") + Context + ":\n";
3448 errs() << Twine("error: ") + Error + "\n";
3452 bool linkDwarf(StringRef OutputFilename, const DebugMap &DM,
3453 const LinkOptions &Options) {
3454 DwarfLinker Linker(OutputFilename, Options);
3455 return Linker.link(DM);