1 //===- tools/dsymutil/DwarfLinker.cpp - Dwarf debug info linker -----------===//
2 //
3 // The LLVM Linker
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 #include "DebugMap.h"
10 #include "BinaryHolder.h"
11 #include "DebugMap.h"
12 #include "dsymutil.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/MC/MCTargetOptionsCommandFlags.h"
35 #include "llvm/Object/MachO.h"
36 #include "llvm/Support/Dwarf.h"
37 #include "llvm/Support/LEB128.h"
38 #include "llvm/Support/TargetRegistry.h"
39 #include "llvm/Target/TargetMachine.h"
40 #include "llvm/Target/TargetOptions.h"
41 #include <string>
42 #include <tuple>
43
44 namespace llvm {
45 namespace dsymutil {
46
47 namespace {
48
49 template <typename KeyT, typename ValT>
50 using HalfOpenIntervalMap =
51 IntervalMap<KeyT, ValT, IntervalMapImpl::NodeSizer<KeyT, ValT>::LeafSize,
52 IntervalMapHalfOpenInfo<KeyT>>;
53
54 typedef HalfOpenIntervalMap<uint64_t, int64_t> FunctionIntervals;
55
56 // FIXME: Delete this structure.
57 struct PatchLocation {
58 DIE::value_iterator I;
59
60 PatchLocation() = default;
PatchLocationllvm::dsymutil::__anon1f629b1b0111::PatchLocation61 PatchLocation(DIE::value_iterator I) : I(I) {}
62
setllvm::dsymutil::__anon1f629b1b0111::PatchLocation63 void set(uint64_t New) const {
64 assert(I);
65 const auto &Old = *I;
66 assert(Old.getType() == DIEValue::isInteger);
67 *I = DIEValue(Old.getAttribute(), Old.getForm(), DIEInteger(New));
68 }
69
getllvm::dsymutil::__anon1f629b1b0111::PatchLocation70 uint64_t get() const {
71 assert(I);
72 return I->getDIEInteger().getValue();
73 }
74 };
75
76 class CompileUnit;
77 struct DeclMapInfo;
78
79 /// A DeclContext is a named program scope that is used for ODR
80 /// uniquing of types.
81 /// The set of DeclContext for the ODR-subject parts of a Dwarf link
82 /// is expanded (and uniqued) with each new object file processed. We
83 /// need to determine the context of each DIE in an linked object file
84 /// to see if the corresponding type has already been emitted.
85 ///
86 /// The contexts are conceptually organised as a tree (eg. a function
87 /// scope is contained in a namespace scope that contains other
88 /// scopes), but storing/accessing them in an actual tree is too
89 /// inefficient: we need to be able to very quickly query a context
90 /// for a given child context by name. Storing a StringMap in each
91 /// DeclContext would be too space inefficient.
92 /// The solution here is to give each DeclContext a link to its parent
93 /// (this allows to walk up the tree), but to query the existance of a
94 /// specific DeclContext using a separate DenseMap keyed on the hash
95 /// of the fully qualified name of the context.
96 class DeclContext {
97 unsigned QualifiedNameHash;
98 uint32_t Line;
99 uint32_t ByteSize;
100 uint16_t Tag;
101 StringRef Name;
102 StringRef File;
103 const DeclContext &Parent;
104 const DWARFDebugInfoEntryMinimal *LastSeenDIE;
105 uint32_t LastSeenCompileUnitID;
106 uint32_t CanonicalDIEOffset;
107
108 friend DeclMapInfo;
109
110 public:
111 typedef DenseSet<DeclContext *, DeclMapInfo> Map;
112
DeclContext()113 DeclContext()
114 : QualifiedNameHash(0), Line(0), ByteSize(0),
115 Tag(dwarf::DW_TAG_compile_unit), Name(), File(), Parent(*this),
116 LastSeenDIE(nullptr), LastSeenCompileUnitID(0), CanonicalDIEOffset(0) {}
117
DeclContext(unsigned Hash,uint32_t Line,uint32_t ByteSize,uint16_t Tag,StringRef Name,StringRef File,const DeclContext & Parent,const DWARFDebugInfoEntryMinimal * LastSeenDIE=nullptr,unsigned CUId=0)118 DeclContext(unsigned Hash, uint32_t Line, uint32_t ByteSize, uint16_t Tag,
119 StringRef Name, StringRef File, const DeclContext &Parent,
120 const DWARFDebugInfoEntryMinimal *LastSeenDIE = nullptr,
121 unsigned CUId = 0)
122 : QualifiedNameHash(Hash), Line(Line), ByteSize(ByteSize), Tag(Tag),
123 Name(Name), File(File), Parent(Parent), LastSeenDIE(LastSeenDIE),
124 LastSeenCompileUnitID(CUId), CanonicalDIEOffset(0) {}
125
getQualifiedNameHash() const126 uint32_t getQualifiedNameHash() const { return QualifiedNameHash; }
127
128 bool setLastSeenDIE(CompileUnit &U, const DWARFDebugInfoEntryMinimal *Die);
129
getCanonicalDIEOffset() const130 uint32_t getCanonicalDIEOffset() const { return CanonicalDIEOffset; }
setCanonicalDIEOffset(uint32_t Offset)131 void setCanonicalDIEOffset(uint32_t Offset) { CanonicalDIEOffset = Offset; }
132
getTag() const133 uint16_t getTag() const { return Tag; }
getName() const134 StringRef getName() const { return Name; }
135 };
136
137 /// Info type for the DenseMap storing the DeclContext pointers.
138 struct DeclMapInfo : private DenseMapInfo<DeclContext *> {
139 using DenseMapInfo<DeclContext *>::getEmptyKey;
140 using DenseMapInfo<DeclContext *>::getTombstoneKey;
141
getHashValuellvm::dsymutil::__anon1f629b1b0111::DeclMapInfo142 static unsigned getHashValue(const DeclContext *Ctxt) {
143 return Ctxt->QualifiedNameHash;
144 }
145
isEqualllvm::dsymutil::__anon1f629b1b0111::DeclMapInfo146 static bool isEqual(const DeclContext *LHS, const DeclContext *RHS) {
147 if (RHS == getEmptyKey() || RHS == getTombstoneKey())
148 return RHS == LHS;
149 return LHS->QualifiedNameHash == RHS->QualifiedNameHash &&
150 LHS->Line == RHS->Line && LHS->ByteSize == RHS->ByteSize &&
151 LHS->Name.data() == RHS->Name.data() &&
152 LHS->File.data() == RHS->File.data() &&
153 LHS->Parent.QualifiedNameHash == RHS->Parent.QualifiedNameHash;
154 }
155 };
156
157 /// This class gives a tree-like API to the DenseMap that stores the
158 /// DeclContext objects. It also holds the BumpPtrAllocator where
159 /// these objects will be allocated.
160 class DeclContextTree {
161 BumpPtrAllocator Allocator;
162 DeclContext Root;
163 DeclContext::Map Contexts;
164
165 public:
166 /// Get the child of \a Context described by \a DIE in \a Unit. The
167 /// required strings will be interned in \a StringPool.
168 /// \returns The child DeclContext along with one bit that is set if
169 /// this context is invalid.
170 /// An invalid context means it shouldn't be considered for uniquing, but its
171 /// not returning null, because some children of that context might be
172 /// uniquing candidates. FIXME: The invalid bit along the return value is to
173 /// emulate some dsymutil-classic functionality.
174 PointerIntPair<DeclContext *, 1>
175 getChildDeclContext(DeclContext &Context,
176 const DWARFDebugInfoEntryMinimal *DIE, CompileUnit &Unit,
177 NonRelocatableStringpool &StringPool, bool InClangModule);
178
getRoot()179 DeclContext &getRoot() { return Root; }
180 };
181
182 /// \brief Stores all information relating to a compile unit, be it in
183 /// its original instance in the object file to its brand new cloned
184 /// and linked DIE tree.
185 class CompileUnit {
186 public:
187 /// \brief Information gathered about a DIE in the object file.
188 struct DIEInfo {
189 int64_t AddrAdjust; ///< Address offset to apply to the described entity.
190 DeclContext *Ctxt; ///< ODR Declaration context.
191 DIE *Clone; ///< Cloned version of that DIE.
192 uint32_t ParentIdx; ///< The index of this DIE's parent.
193 bool Keep : 1; ///< Is the DIE part of the linked output?
194 bool InDebugMap : 1;///< Was this DIE's entity found in the map?
195 bool Prune : 1; ///< Is this a pure forward declaration we can strip?
196 };
197
CompileUnit(DWARFUnit & OrigUnit,unsigned ID,bool CanUseODR,StringRef ClangModuleName)198 CompileUnit(DWARFUnit &OrigUnit, unsigned ID, bool CanUseODR,
199 StringRef ClangModuleName)
200 : OrigUnit(OrigUnit), ID(ID), LowPc(UINT64_MAX), HighPc(0), RangeAlloc(),
201 Ranges(RangeAlloc), ClangModuleName(ClangModuleName) {
202 Info.resize(OrigUnit.getNumDIEs());
203
204 const auto *CUDie = OrigUnit.getUnitDIE(false);
205 unsigned Lang = CUDie->getAttributeValueAsUnsignedConstant(
206 &OrigUnit, dwarf::DW_AT_language, 0);
207 HasODR = CanUseODR && (Lang == dwarf::DW_LANG_C_plus_plus ||
208 Lang == dwarf::DW_LANG_C_plus_plus_03 ||
209 Lang == dwarf::DW_LANG_C_plus_plus_11 ||
210 Lang == dwarf::DW_LANG_C_plus_plus_14 ||
211 Lang == dwarf::DW_LANG_ObjC_plus_plus);
212 }
213
CompileUnit(CompileUnit && RHS)214 CompileUnit(CompileUnit &&RHS)
215 : OrigUnit(RHS.OrigUnit), Info(std::move(RHS.Info)),
216 CUDie(std::move(RHS.CUDie)), StartOffset(RHS.StartOffset),
217 NextUnitOffset(RHS.NextUnitOffset), RangeAlloc(), Ranges(RangeAlloc) {
218 // The CompileUnit container has been 'reserve()'d with the right
219 // size. We cannot move the IntervalMap anyway.
220 llvm_unreachable("CompileUnits should not be moved.");
221 }
222
getOrigUnit() const223 DWARFUnit &getOrigUnit() const { return OrigUnit; }
224
getUniqueID() const225 unsigned getUniqueID() const { return ID; }
226
getOutputUnitDIE() const227 DIE *getOutputUnitDIE() const { return CUDie; }
setOutputUnitDIE(DIE * Die)228 void setOutputUnitDIE(DIE *Die) { CUDie = Die; }
229
hasODR() const230 bool hasODR() const { return HasODR; }
isClangModule() const231 bool isClangModule() const { return !ClangModuleName.empty(); }
getClangModuleName() const232 const std::string &getClangModuleName() const { return ClangModuleName; }
233
getInfo(unsigned Idx)234 DIEInfo &getInfo(unsigned Idx) { return Info[Idx]; }
getInfo(unsigned Idx) const235 const DIEInfo &getInfo(unsigned Idx) const { return Info[Idx]; }
236
getStartOffset() const237 uint64_t getStartOffset() const { return StartOffset; }
getNextUnitOffset() const238 uint64_t getNextUnitOffset() const { return NextUnitOffset; }
setStartOffset(uint64_t DebugInfoSize)239 void setStartOffset(uint64_t DebugInfoSize) { StartOffset = DebugInfoSize; }
240
getLowPc() const241 uint64_t getLowPc() const { return LowPc; }
getHighPc() const242 uint64_t getHighPc() const { return HighPc; }
243
getUnitRangesAttribute() const244 Optional<PatchLocation> getUnitRangesAttribute() const {
245 return UnitRangeAttribute;
246 }
getFunctionRanges() const247 const FunctionIntervals &getFunctionRanges() const { return Ranges; }
getRangesAttributes() const248 const std::vector<PatchLocation> &getRangesAttributes() const {
249 return RangeAttributes;
250 }
251
252 const std::vector<std::pair<PatchLocation, int64_t>> &
getLocationAttributes() const253 getLocationAttributes() const {
254 return LocationAttributes;
255 }
256
setHasInterestingContent()257 void setHasInterestingContent() { HasInterestingContent = true; }
hasInterestingContent()258 bool hasInterestingContent() { return HasInterestingContent; }
259
260 /// Mark every DIE in this unit as kept. This function also
261 /// marks variables as InDebugMap so that they appear in the
262 /// reconstructed accelerator tables.
263 void markEverythingAsKept();
264
265 /// \brief Compute the end offset for this unit. Must be
266 /// called after the CU's DIEs have been cloned.
267 /// \returns the next unit offset (which is also the current
268 /// debug_info section size).
269 uint64_t computeNextUnitOffset();
270
271 /// \brief Keep track of a forward reference to DIE \p Die in \p
272 /// RefUnit by \p Attr. The attribute should be fixed up later to
273 /// point to the absolute offset of \p Die in the debug_info section
274 /// or to the canonical offset of \p Ctxt if it is non-null.
275 void noteForwardReference(DIE *Die, const CompileUnit *RefUnit,
276 DeclContext *Ctxt, PatchLocation Attr);
277
278 /// \brief Apply all fixups recored by noteForwardReference().
279 void fixupForwardReferences();
280
281 /// \brief Add a function range [\p LowPC, \p HighPC) that is
282 /// relocatad by applying offset \p PCOffset.
283 void addFunctionRange(uint64_t LowPC, uint64_t HighPC, int64_t PCOffset);
284
285 /// \brief Keep track of a DW_AT_range attribute that we will need to
286 /// patch up later.
287 void noteRangeAttribute(const DIE &Die, PatchLocation Attr);
288
289 /// \brief Keep track of a location attribute pointing to a location
290 /// list in the debug_loc section.
291 void noteLocationAttribute(PatchLocation Attr, int64_t PcOffset);
292
293 /// \brief Add a name accelerator entry for \p Die with \p Name
294 /// which is stored in the string table at \p Offset.
295 void addNameAccelerator(const DIE *Die, const char *Name, uint32_t Offset,
296 bool SkipPubnamesSection = false);
297
298 /// \brief Add a type accelerator entry for \p Die with \p Name
299 /// which is stored in the string table at \p Offset.
300 void addTypeAccelerator(const DIE *Die, const char *Name, uint32_t Offset);
301
302 struct AccelInfo {
303 StringRef Name; ///< Name of the entry.
304 const DIE *Die; ///< DIE this entry describes.
305 uint32_t NameOffset; ///< Offset of Name in the string pool.
306 bool SkipPubSection; ///< Emit this entry only in the apple_* sections.
307
AccelInfollvm::dsymutil::__anon1f629b1b0111::CompileUnit::AccelInfo308 AccelInfo(StringRef Name, const DIE *Die, uint32_t NameOffset,
309 bool SkipPubSection = false)
310 : Name(Name), Die(Die), NameOffset(NameOffset),
311 SkipPubSection(SkipPubSection) {}
312 };
313
getPubnames() const314 const std::vector<AccelInfo> &getPubnames() const { return Pubnames; }
getPubtypes() const315 const std::vector<AccelInfo> &getPubtypes() const { return Pubtypes; }
316
317 /// Get the full path for file \a FileNum in the line table
getResolvedPath(unsigned FileNum)318 const char *getResolvedPath(unsigned FileNum) {
319 if (FileNum >= ResolvedPaths.size())
320 return nullptr;
321 return ResolvedPaths[FileNum].size() ? ResolvedPaths[FileNum].c_str()
322 : nullptr;
323 }
324
325 /// Set the fully resolved path for the line-table's file \a FileNum
326 /// to \a Path.
setResolvedPath(unsigned FileNum,const std::string & Path)327 void setResolvedPath(unsigned FileNum, const std::string &Path) {
328 if (ResolvedPaths.size() <= FileNum)
329 ResolvedPaths.resize(FileNum + 1);
330 ResolvedPaths[FileNum] = Path;
331 }
332
333 private:
334 DWARFUnit &OrigUnit;
335 unsigned ID;
336 std::vector<DIEInfo> Info; ///< DIE info indexed by DIE index.
337 DIE *CUDie; ///< Root of the linked DIE tree.
338
339 uint64_t StartOffset;
340 uint64_t NextUnitOffset;
341
342 uint64_t LowPc;
343 uint64_t HighPc;
344
345 /// \brief A list of attributes to fixup with the absolute offset of
346 /// a DIE in the debug_info section.
347 ///
348 /// The offsets for the attributes in this array couldn't be set while
349 /// cloning because for cross-cu forward refences the target DIE's
350 /// offset isn't known you emit the reference attribute.
351 std::vector<std::tuple<DIE *, const CompileUnit *, DeclContext *,
352 PatchLocation>> ForwardDIEReferences;
353
354 FunctionIntervals::Allocator RangeAlloc;
355 /// \brief The ranges in that interval map are the PC ranges for
356 /// functions in this unit, associated with the PC offset to apply
357 /// to the addresses to get the linked address.
358 FunctionIntervals Ranges;
359
360 /// \brief DW_AT_ranges attributes to patch after we have gathered
361 /// all the unit's function addresses.
362 /// @{
363 std::vector<PatchLocation> RangeAttributes;
364 Optional<PatchLocation> UnitRangeAttribute;
365 /// @}
366
367 /// \brief Location attributes that need to be transfered from th
368 /// original debug_loc section to the liked one. They are stored
369 /// along with the PC offset that is to be applied to their
370 /// function's address.
371 std::vector<std::pair<PatchLocation, int64_t>> LocationAttributes;
372
373 /// \brief Accelerator entries for the unit, both for the pub*
374 /// sections and the apple* ones.
375 /// @{
376 std::vector<AccelInfo> Pubnames;
377 std::vector<AccelInfo> Pubtypes;
378 /// @}
379
380 /// Cached resolved paths from the line table.
381 std::vector<std::string> ResolvedPaths;
382
383 /// Is this unit subject to the ODR rule?
384 bool HasODR;
385 /// Did a DIE actually contain a valid reloc?
386 bool HasInterestingContent;
387 /// If this is a Clang module, this holds the module's name.
388 std::string ClangModuleName;
389 };
390
markEverythingAsKept()391 void CompileUnit::markEverythingAsKept() {
392 for (auto &I : Info)
393 // Mark everything that wasn't explicity marked for pruning.
394 I.Keep = !I.Prune;
395 }
396
computeNextUnitOffset()397 uint64_t CompileUnit::computeNextUnitOffset() {
398 NextUnitOffset = StartOffset + 11 /* Header size */;
399 // The root DIE might be null, meaning that the Unit had nothing to
400 // contribute to the linked output. In that case, we will emit the
401 // unit header without any actual DIE.
402 if (CUDie)
403 NextUnitOffset += CUDie->getSize();
404 return NextUnitOffset;
405 }
406
407 /// \brief Keep track of a forward cross-cu reference from this unit
408 /// to \p Die that lives in \p RefUnit.
noteForwardReference(DIE * Die,const CompileUnit * RefUnit,DeclContext * Ctxt,PatchLocation Attr)409 void CompileUnit::noteForwardReference(DIE *Die, const CompileUnit *RefUnit,
410 DeclContext *Ctxt, PatchLocation Attr) {
411 ForwardDIEReferences.emplace_back(Die, RefUnit, Ctxt, Attr);
412 }
413
414 /// \brief Apply all fixups recorded by noteForwardReference().
fixupForwardReferences()415 void CompileUnit::fixupForwardReferences() {
416 for (const auto &Ref : ForwardDIEReferences) {
417 DIE *RefDie;
418 const CompileUnit *RefUnit;
419 PatchLocation Attr;
420 DeclContext *Ctxt;
421 std::tie(RefDie, RefUnit, Ctxt, Attr) = Ref;
422 if (Ctxt && Ctxt->getCanonicalDIEOffset())
423 Attr.set(Ctxt->getCanonicalDIEOffset());
424 else
425 Attr.set(RefDie->getOffset() + RefUnit->getStartOffset());
426 }
427 }
428
addFunctionRange(uint64_t FuncLowPc,uint64_t FuncHighPc,int64_t PcOffset)429 void CompileUnit::addFunctionRange(uint64_t FuncLowPc, uint64_t FuncHighPc,
430 int64_t PcOffset) {
431 Ranges.insert(FuncLowPc, FuncHighPc, PcOffset);
432 this->LowPc = std::min(LowPc, FuncLowPc + PcOffset);
433 this->HighPc = std::max(HighPc, FuncHighPc + PcOffset);
434 }
435
noteRangeAttribute(const DIE & Die,PatchLocation Attr)436 void CompileUnit::noteRangeAttribute(const DIE &Die, PatchLocation Attr) {
437 if (Die.getTag() != dwarf::DW_TAG_compile_unit)
438 RangeAttributes.push_back(Attr);
439 else
440 UnitRangeAttribute = Attr;
441 }
442
noteLocationAttribute(PatchLocation Attr,int64_t PcOffset)443 void CompileUnit::noteLocationAttribute(PatchLocation Attr, int64_t PcOffset) {
444 LocationAttributes.emplace_back(Attr, PcOffset);
445 }
446
447 /// \brief Add a name accelerator entry for \p Die with \p Name
448 /// which is stored in the string table at \p Offset.
addNameAccelerator(const DIE * Die,const char * Name,uint32_t Offset,bool SkipPubSection)449 void CompileUnit::addNameAccelerator(const DIE *Die, const char *Name,
450 uint32_t Offset, bool SkipPubSection) {
451 Pubnames.emplace_back(Name, Die, Offset, SkipPubSection);
452 }
453
454 /// \brief Add a type accelerator entry for \p Die with \p Name
455 /// which is stored in the string table at \p Offset.
addTypeAccelerator(const DIE * Die,const char * Name,uint32_t Offset)456 void CompileUnit::addTypeAccelerator(const DIE *Die, const char *Name,
457 uint32_t Offset) {
458 Pubtypes.emplace_back(Name, Die, Offset, false);
459 }
460
461 /// \brief The Dwarf streaming logic
462 ///
463 /// All interactions with the MC layer that is used to build the debug
464 /// information binary representation are handled in this class.
465 class DwarfStreamer {
466 /// \defgroup MCObjects MC layer objects constructed by the streamer
467 /// @{
468 std::unique_ptr<MCRegisterInfo> MRI;
469 std::unique_ptr<MCAsmInfo> MAI;
470 std::unique_ptr<MCObjectFileInfo> MOFI;
471 std::unique_ptr<MCContext> MC;
472 MCAsmBackend *MAB; // Owned by MCStreamer
473 std::unique_ptr<MCInstrInfo> MII;
474 std::unique_ptr<MCSubtargetInfo> MSTI;
475 MCCodeEmitter *MCE; // Owned by MCStreamer
476 MCStreamer *MS; // Owned by AsmPrinter
477 std::unique_ptr<TargetMachine> TM;
478 std::unique_ptr<AsmPrinter> Asm;
479 /// @}
480
481 /// \brief the file we stream the linked Dwarf to.
482 std::unique_ptr<raw_fd_ostream> OutFile;
483
484 uint32_t RangesSectionSize;
485 uint32_t LocSectionSize;
486 uint32_t LineSectionSize;
487 uint32_t FrameSectionSize;
488
489 /// \brief Emit the pubnames or pubtypes section contribution for \p
490 /// Unit into \p Sec. The data is provided in \p Names.
491 void emitPubSectionForUnit(MCSection *Sec, StringRef Name,
492 const CompileUnit &Unit,
493 const std::vector<CompileUnit::AccelInfo> &Names);
494
495 public:
496 /// \brief Actually create the streamer and the ouptut file.
497 ///
498 /// This could be done directly in the constructor, but it feels
499 /// more natural to handle errors through return value.
500 bool init(Triple TheTriple, StringRef OutputFilename);
501
502 /// \brief Dump the file to the disk.
503 bool finish(const DebugMap &);
504
getAsmPrinter() const505 AsmPrinter &getAsmPrinter() const { return *Asm; }
506
507 /// \brief Set the current output section to debug_info and change
508 /// the MC Dwarf version to \p DwarfVersion.
509 void switchToDebugInfoSection(unsigned DwarfVersion);
510
511 /// \brief Emit the compilation unit header for \p Unit in the
512 /// debug_info section.
513 ///
514 /// As a side effect, this also switches the current Dwarf version
515 /// of the MC layer to the one of U.getOrigUnit().
516 void emitCompileUnitHeader(CompileUnit &Unit);
517
518 /// \brief Recursively emit the DIE tree rooted at \p Die.
519 void emitDIE(DIE &Die);
520
521 /// \brief Emit the abbreviation table \p Abbrevs to the
522 /// debug_abbrev section.
523 void emitAbbrevs(const std::vector<std::unique_ptr<DIEAbbrev>> &Abbrevs);
524
525 /// \brief Emit the string table described by \p Pool.
526 void emitStrings(const NonRelocatableStringpool &Pool);
527
528 /// \brief Emit debug_ranges for \p FuncRange by translating the
529 /// original \p Entries.
530 void emitRangesEntries(
531 int64_t UnitPcOffset, uint64_t OrigLowPc,
532 FunctionIntervals::const_iterator FuncRange,
533 const std::vector<DWARFDebugRangeList::RangeListEntry> &Entries,
534 unsigned AddressSize);
535
536 /// \brief Emit debug_aranges entries for \p Unit and if \p
537 /// DoRangesSection is true, also emit the debug_ranges entries for
538 /// the DW_TAG_compile_unit's DW_AT_ranges attribute.
539 void emitUnitRangesEntries(CompileUnit &Unit, bool DoRangesSection);
540
getRangesSectionSize() const541 uint32_t getRangesSectionSize() const { return RangesSectionSize; }
542
543 /// \brief Emit the debug_loc contribution for \p Unit by copying
544 /// the entries from \p Dwarf and offseting them. Update the
545 /// location attributes to point to the new entries.
546 void emitLocationsForUnit(const CompileUnit &Unit, DWARFContext &Dwarf);
547
548 /// \brief Emit the line table described in \p Rows into the
549 /// debug_line section.
550 void emitLineTableForUnit(MCDwarfLineTableParams Params,
551 StringRef PrologueBytes, unsigned MinInstLength,
552 std::vector<DWARFDebugLine::Row> &Rows,
553 unsigned AdddressSize);
554
getLineSectionSize() const555 uint32_t getLineSectionSize() const { return LineSectionSize; }
556
557 /// \brief Emit the .debug_pubnames contribution for \p Unit.
558 void emitPubNamesForUnit(const CompileUnit &Unit);
559
560 /// \brief Emit the .debug_pubtypes contribution for \p Unit.
561 void emitPubTypesForUnit(const CompileUnit &Unit);
562
563 /// \brief Emit a CIE.
564 void emitCIE(StringRef CIEBytes);
565
566 /// \brief Emit an FDE with data \p Bytes.
567 void emitFDE(uint32_t CIEOffset, uint32_t AddreSize, uint32_t Address,
568 StringRef Bytes);
569
getFrameSectionSize() const570 uint32_t getFrameSectionSize() const { return FrameSectionSize; }
571 };
572
init(Triple TheTriple,StringRef OutputFilename)573 bool DwarfStreamer::init(Triple TheTriple, StringRef OutputFilename) {
574 std::string ErrorStr;
575 std::string TripleName;
576 StringRef Context = "dwarf streamer init";
577
578 // Get the target.
579 const Target *TheTarget =
580 TargetRegistry::lookupTarget(TripleName, TheTriple, ErrorStr);
581 if (!TheTarget)
582 return error(ErrorStr, Context);
583 TripleName = TheTriple.getTriple();
584
585 // Create all the MC Objects.
586 MRI.reset(TheTarget->createMCRegInfo(TripleName));
587 if (!MRI)
588 return error(Twine("no register info for target ") + TripleName, Context);
589
590 MAI.reset(TheTarget->createMCAsmInfo(*MRI, TripleName));
591 if (!MAI)
592 return error("no asm info for target " + TripleName, Context);
593
594 MOFI.reset(new MCObjectFileInfo);
595 MC.reset(new MCContext(MAI.get(), MRI.get(), MOFI.get()));
596 MOFI->InitMCObjectFileInfo(TheTriple, Reloc::Default, CodeModel::Default,
597 *MC);
598
599 MAB = TheTarget->createMCAsmBackend(*MRI, TripleName, "");
600 if (!MAB)
601 return error("no asm backend for target " + TripleName, Context);
602
603 MII.reset(TheTarget->createMCInstrInfo());
604 if (!MII)
605 return error("no instr info info for target " + TripleName, Context);
606
607 MSTI.reset(TheTarget->createMCSubtargetInfo(TripleName, "", ""));
608 if (!MSTI)
609 return error("no subtarget info for target " + TripleName, Context);
610
611 MCE = TheTarget->createMCCodeEmitter(*MII, *MRI, *MC);
612 if (!MCE)
613 return error("no code emitter for target " + TripleName, Context);
614
615 // Create the output file.
616 std::error_code EC;
617 OutFile =
618 llvm::make_unique<raw_fd_ostream>(OutputFilename, EC, sys::fs::F_None);
619 if (EC)
620 return error(Twine(OutputFilename) + ": " + EC.message(), Context);
621
622 MCTargetOptions MCOptions = InitMCTargetOptionsFromFlags();
623 MS = TheTarget->createMCObjectStreamer(
624 TheTriple, *MC, *MAB, *OutFile, MCE, *MSTI, MCOptions.MCRelaxAll,
625 MCOptions.MCIncrementalLinkerCompatible,
626 /*DWARFMustBeAtTheEnd*/ false);
627 if (!MS)
628 return error("no object streamer for target " + TripleName, Context);
629
630 // Finally create the AsmPrinter we'll use to emit the DIEs.
631 TM.reset(TheTarget->createTargetMachine(TripleName, "", "", TargetOptions()));
632 if (!TM)
633 return error("no target machine for target " + TripleName, Context);
634
635 Asm.reset(TheTarget->createAsmPrinter(*TM, std::unique_ptr<MCStreamer>(MS)));
636 if (!Asm)
637 return error("no asm printer for target " + TripleName, Context);
638
639 RangesSectionSize = 0;
640 LocSectionSize = 0;
641 LineSectionSize = 0;
642 FrameSectionSize = 0;
643
644 return true;
645 }
646
finish(const DebugMap & DM)647 bool DwarfStreamer::finish(const DebugMap &DM) {
648 if (DM.getTriple().isOSDarwin() && !DM.getBinaryPath().empty())
649 return MachOUtils::generateDsymCompanion(DM, *MS, *OutFile);
650
651 MS->Finish();
652 return true;
653 }
654
655 /// \brief Set the current output section to debug_info and change
656 /// the MC Dwarf version to \p DwarfVersion.
switchToDebugInfoSection(unsigned DwarfVersion)657 void DwarfStreamer::switchToDebugInfoSection(unsigned DwarfVersion) {
658 MS->SwitchSection(MOFI->getDwarfInfoSection());
659 MC->setDwarfVersion(DwarfVersion);
660 }
661
662 /// \brief Emit the compilation unit header for \p Unit in the
663 /// debug_info section.
664 ///
665 /// A Dwarf scetion header is encoded as:
666 /// uint32_t Unit length (omiting this field)
667 /// uint16_t Version
668 /// uint32_t Abbreviation table offset
669 /// uint8_t Address size
670 ///
671 /// Leading to a total of 11 bytes.
emitCompileUnitHeader(CompileUnit & Unit)672 void DwarfStreamer::emitCompileUnitHeader(CompileUnit &Unit) {
673 unsigned Version = Unit.getOrigUnit().getVersion();
674 switchToDebugInfoSection(Version);
675
676 // Emit size of content not including length itself. The size has
677 // already been computed in CompileUnit::computeOffsets(). Substract
678 // 4 to that size to account for the length field.
679 Asm->EmitInt32(Unit.getNextUnitOffset() - Unit.getStartOffset() - 4);
680 Asm->EmitInt16(Version);
681 // We share one abbreviations table across all units so it's always at the
682 // start of the section.
683 Asm->EmitInt32(0);
684 Asm->EmitInt8(Unit.getOrigUnit().getAddressByteSize());
685 }
686
687 /// \brief Emit the \p Abbrevs array as the shared abbreviation table
688 /// for the linked Dwarf file.
emitAbbrevs(const std::vector<std::unique_ptr<DIEAbbrev>> & Abbrevs)689 void DwarfStreamer::emitAbbrevs(
690 const std::vector<std::unique_ptr<DIEAbbrev>> &Abbrevs) {
691 MS->SwitchSection(MOFI->getDwarfAbbrevSection());
692 Asm->emitDwarfAbbrevs(Abbrevs);
693 }
694
695 /// \brief Recursively emit the DIE tree rooted at \p Die.
emitDIE(DIE & Die)696 void DwarfStreamer::emitDIE(DIE &Die) {
697 MS->SwitchSection(MOFI->getDwarfInfoSection());
698 Asm->emitDwarfDIE(Die);
699 }
700
701 /// \brief Emit the debug_str section stored in \p Pool.
emitStrings(const NonRelocatableStringpool & Pool)702 void DwarfStreamer::emitStrings(const NonRelocatableStringpool &Pool) {
703 Asm->OutStreamer->SwitchSection(MOFI->getDwarfStrSection());
704 for (auto *Entry = Pool.getFirstEntry(); Entry;
705 Entry = Pool.getNextEntry(Entry))
706 Asm->OutStreamer->EmitBytes(
707 StringRef(Entry->getKey().data(), Entry->getKey().size() + 1));
708 }
709
710 /// \brief Emit the debug_range section contents for \p FuncRange by
711 /// translating the original \p Entries. The debug_range section
712 /// format is totally trivial, consisting just of pairs of address
713 /// sized addresses describing the ranges.
emitRangesEntries(int64_t UnitPcOffset,uint64_t OrigLowPc,FunctionIntervals::const_iterator FuncRange,const std::vector<DWARFDebugRangeList::RangeListEntry> & Entries,unsigned AddressSize)714 void DwarfStreamer::emitRangesEntries(
715 int64_t UnitPcOffset, uint64_t OrigLowPc,
716 FunctionIntervals::const_iterator FuncRange,
717 const std::vector<DWARFDebugRangeList::RangeListEntry> &Entries,
718 unsigned AddressSize) {
719 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfRangesSection());
720
721 // Offset each range by the right amount.
722 int64_t PcOffset = Entries.empty() ? 0 : FuncRange.value() + UnitPcOffset;
723 for (const auto &Range : Entries) {
724 if (Range.isBaseAddressSelectionEntry(AddressSize)) {
725 warn("unsupported base address selection operation",
726 "emitting debug_ranges");
727 break;
728 }
729 // Do not emit empty ranges.
730 if (Range.StartAddress == Range.EndAddress)
731 continue;
732
733 // All range entries should lie in the function range.
734 if (!(Range.StartAddress + OrigLowPc >= FuncRange.start() &&
735 Range.EndAddress + OrigLowPc <= FuncRange.stop()))
736 warn("inconsistent range data.", "emitting debug_ranges");
737 MS->EmitIntValue(Range.StartAddress + PcOffset, AddressSize);
738 MS->EmitIntValue(Range.EndAddress + PcOffset, AddressSize);
739 RangesSectionSize += 2 * AddressSize;
740 }
741
742 // Add the terminator entry.
743 MS->EmitIntValue(0, AddressSize);
744 MS->EmitIntValue(0, AddressSize);
745 RangesSectionSize += 2 * AddressSize;
746 }
747
748 /// \brief Emit the debug_aranges contribution of a unit and
749 /// if \p DoDebugRanges is true the debug_range contents for a
750 /// compile_unit level DW_AT_ranges attribute (Which are basically the
751 /// same thing with a different base address).
752 /// Just aggregate all the ranges gathered inside that unit.
emitUnitRangesEntries(CompileUnit & Unit,bool DoDebugRanges)753 void DwarfStreamer::emitUnitRangesEntries(CompileUnit &Unit,
754 bool DoDebugRanges) {
755 unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
756 // Gather the ranges in a vector, so that we can simplify them. The
757 // IntervalMap will have coalesced the non-linked ranges, but here
758 // we want to coalesce the linked addresses.
759 std::vector<std::pair<uint64_t, uint64_t>> Ranges;
760 const auto &FunctionRanges = Unit.getFunctionRanges();
761 for (auto Range = FunctionRanges.begin(), End = FunctionRanges.end();
762 Range != End; ++Range)
763 Ranges.push_back(std::make_pair(Range.start() + Range.value(),
764 Range.stop() + Range.value()));
765
766 // The object addresses where sorted, but again, the linked
767 // addresses might end up in a different order.
768 std::sort(Ranges.begin(), Ranges.end());
769
770 if (!Ranges.empty()) {
771 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfARangesSection());
772
773 MCSymbol *BeginLabel = Asm->createTempSymbol("Barange");
774 MCSymbol *EndLabel = Asm->createTempSymbol("Earange");
775
776 unsigned HeaderSize =
777 sizeof(int32_t) + // Size of contents (w/o this field
778 sizeof(int16_t) + // DWARF ARange version number
779 sizeof(int32_t) + // Offset of CU in the .debug_info section
780 sizeof(int8_t) + // Pointer Size (in bytes)
781 sizeof(int8_t); // Segment Size (in bytes)
782
783 unsigned TupleSize = AddressSize * 2;
784 unsigned Padding = OffsetToAlignment(HeaderSize, TupleSize);
785
786 Asm->EmitLabelDifference(EndLabel, BeginLabel, 4); // Arange length
787 Asm->OutStreamer->EmitLabel(BeginLabel);
788 Asm->EmitInt16(dwarf::DW_ARANGES_VERSION); // Version number
789 Asm->EmitInt32(Unit.getStartOffset()); // Corresponding unit's offset
790 Asm->EmitInt8(AddressSize); // Address size
791 Asm->EmitInt8(0); // Segment size
792
793 Asm->OutStreamer->EmitFill(Padding, 0x0);
794
795 for (auto Range = Ranges.begin(), End = Ranges.end(); Range != End;
796 ++Range) {
797 uint64_t RangeStart = Range->first;
798 MS->EmitIntValue(RangeStart, AddressSize);
799 while ((Range + 1) != End && Range->second == (Range + 1)->first)
800 ++Range;
801 MS->EmitIntValue(Range->second - RangeStart, AddressSize);
802 }
803
804 // Emit terminator
805 Asm->OutStreamer->EmitIntValue(0, AddressSize);
806 Asm->OutStreamer->EmitIntValue(0, AddressSize);
807 Asm->OutStreamer->EmitLabel(EndLabel);
808 }
809
810 if (!DoDebugRanges)
811 return;
812
813 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfRangesSection());
814 // Offset each range by the right amount.
815 int64_t PcOffset = -Unit.getLowPc();
816 // Emit coalesced ranges.
817 for (auto Range = Ranges.begin(), End = Ranges.end(); Range != End; ++Range) {
818 MS->EmitIntValue(Range->first + PcOffset, AddressSize);
819 while (Range + 1 != End && Range->second == (Range + 1)->first)
820 ++Range;
821 MS->EmitIntValue(Range->second + PcOffset, AddressSize);
822 RangesSectionSize += 2 * AddressSize;
823 }
824
825 // Add the terminator entry.
826 MS->EmitIntValue(0, AddressSize);
827 MS->EmitIntValue(0, AddressSize);
828 RangesSectionSize += 2 * AddressSize;
829 }
830
831 /// \brief Emit location lists for \p Unit and update attribtues to
832 /// point to the new entries.
emitLocationsForUnit(const CompileUnit & Unit,DWARFContext & Dwarf)833 void DwarfStreamer::emitLocationsForUnit(const CompileUnit &Unit,
834 DWARFContext &Dwarf) {
835 const auto &Attributes = Unit.getLocationAttributes();
836
837 if (Attributes.empty())
838 return;
839
840 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLocSection());
841
842 unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
843 const DWARFSection &InputSec = Dwarf.getLocSection();
844 DataExtractor Data(InputSec.Data, Dwarf.isLittleEndian(), AddressSize);
845 DWARFUnit &OrigUnit = Unit.getOrigUnit();
846 const auto *OrigUnitDie = OrigUnit.getUnitDIE(false);
847 int64_t UnitPcOffset = 0;
848 uint64_t OrigLowPc = OrigUnitDie->getAttributeValueAsAddress(
849 &OrigUnit, dwarf::DW_AT_low_pc, -1ULL);
850 if (OrigLowPc != -1ULL)
851 UnitPcOffset = int64_t(OrigLowPc) - Unit.getLowPc();
852
853 for (const auto &Attr : Attributes) {
854 uint32_t Offset = Attr.first.get();
855 Attr.first.set(LocSectionSize);
856 // This is the quantity to add to the old location address to get
857 // the correct address for the new one.
858 int64_t LocPcOffset = Attr.second + UnitPcOffset;
859 while (Data.isValidOffset(Offset)) {
860 uint64_t Low = Data.getUnsigned(&Offset, AddressSize);
861 uint64_t High = Data.getUnsigned(&Offset, AddressSize);
862 LocSectionSize += 2 * AddressSize;
863 if (Low == 0 && High == 0) {
864 Asm->OutStreamer->EmitIntValue(0, AddressSize);
865 Asm->OutStreamer->EmitIntValue(0, AddressSize);
866 break;
867 }
868 Asm->OutStreamer->EmitIntValue(Low + LocPcOffset, AddressSize);
869 Asm->OutStreamer->EmitIntValue(High + LocPcOffset, AddressSize);
870 uint64_t Length = Data.getU16(&Offset);
871 Asm->OutStreamer->EmitIntValue(Length, 2);
872 // Just copy the bytes over.
873 Asm->OutStreamer->EmitBytes(
874 StringRef(InputSec.Data.substr(Offset, Length)));
875 Offset += Length;
876 LocSectionSize += Length + 2;
877 }
878 }
879 }
880
emitLineTableForUnit(MCDwarfLineTableParams Params,StringRef PrologueBytes,unsigned MinInstLength,std::vector<DWARFDebugLine::Row> & Rows,unsigned PointerSize)881 void DwarfStreamer::emitLineTableForUnit(MCDwarfLineTableParams Params,
882 StringRef PrologueBytes,
883 unsigned MinInstLength,
884 std::vector<DWARFDebugLine::Row> &Rows,
885 unsigned PointerSize) {
886 // Switch to the section where the table will be emitted into.
887 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLineSection());
888 MCSymbol *LineStartSym = MC->createTempSymbol();
889 MCSymbol *LineEndSym = MC->createTempSymbol();
890
891 // The first 4 bytes is the total length of the information for this
892 // compilation unit (not including these 4 bytes for the length).
893 Asm->EmitLabelDifference(LineEndSym, LineStartSym, 4);
894 Asm->OutStreamer->EmitLabel(LineStartSym);
895 // Copy Prologue.
896 MS->EmitBytes(PrologueBytes);
897 LineSectionSize += PrologueBytes.size() + 4;
898
899 SmallString<128> EncodingBuffer;
900 raw_svector_ostream EncodingOS(EncodingBuffer);
901
902 if (Rows.empty()) {
903 // We only have the dummy entry, dsymutil emits an entry with a 0
904 // address in that case.
905 MCDwarfLineAddr::Encode(*MC, Params, INT64_MAX, 0, EncodingOS);
906 MS->EmitBytes(EncodingOS.str());
907 LineSectionSize += EncodingBuffer.size();
908 MS->EmitLabel(LineEndSym);
909 return;
910 }
911
912 // Line table state machine fields
913 unsigned FileNum = 1;
914 unsigned LastLine = 1;
915 unsigned Column = 0;
916 unsigned IsStatement = 1;
917 unsigned Isa = 0;
918 uint64_t Address = -1ULL;
919
920 unsigned RowsSinceLastSequence = 0;
921
922 for (unsigned Idx = 0; Idx < Rows.size(); ++Idx) {
923 auto &Row = Rows[Idx];
924
925 int64_t AddressDelta;
926 if (Address == -1ULL) {
927 MS->EmitIntValue(dwarf::DW_LNS_extended_op, 1);
928 MS->EmitULEB128IntValue(PointerSize + 1);
929 MS->EmitIntValue(dwarf::DW_LNE_set_address, 1);
930 MS->EmitIntValue(Row.Address, PointerSize);
931 LineSectionSize += 2 + PointerSize + getULEB128Size(PointerSize + 1);
932 AddressDelta = 0;
933 } else {
934 AddressDelta = (Row.Address - Address) / MinInstLength;
935 }
936
937 // FIXME: code copied and transfromed from
938 // MCDwarf.cpp::EmitDwarfLineTable. We should find a way to share
939 // this code, but the current compatibility requirement with
940 // classic dsymutil makes it hard. Revisit that once this
941 // requirement is dropped.
942
943 if (FileNum != Row.File) {
944 FileNum = Row.File;
945 MS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
946 MS->EmitULEB128IntValue(FileNum);
947 LineSectionSize += 1 + getULEB128Size(FileNum);
948 }
949 if (Column != Row.Column) {
950 Column = Row.Column;
951 MS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
952 MS->EmitULEB128IntValue(Column);
953 LineSectionSize += 1 + getULEB128Size(Column);
954 }
955
956 // FIXME: We should handle the discriminator here, but dsymutil
957 // doesn' consider it, thus ignore it for now.
958
959 if (Isa != Row.Isa) {
960 Isa = Row.Isa;
961 MS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
962 MS->EmitULEB128IntValue(Isa);
963 LineSectionSize += 1 + getULEB128Size(Isa);
964 }
965 if (IsStatement != Row.IsStmt) {
966 IsStatement = Row.IsStmt;
967 MS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
968 LineSectionSize += 1;
969 }
970 if (Row.BasicBlock) {
971 MS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1);
972 LineSectionSize += 1;
973 }
974
975 if (Row.PrologueEnd) {
976 MS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
977 LineSectionSize += 1;
978 }
979
980 if (Row.EpilogueBegin) {
981 MS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);
982 LineSectionSize += 1;
983 }
984
985 int64_t LineDelta = int64_t(Row.Line) - LastLine;
986 if (!Row.EndSequence) {
987 MCDwarfLineAddr::Encode(*MC, Params, LineDelta, AddressDelta, EncodingOS);
988 MS->EmitBytes(EncodingOS.str());
989 LineSectionSize += EncodingBuffer.size();
990 EncodingBuffer.resize(0);
991 Address = Row.Address;
992 LastLine = Row.Line;
993 RowsSinceLastSequence++;
994 } else {
995 if (LineDelta) {
996 MS->EmitIntValue(dwarf::DW_LNS_advance_line, 1);
997 MS->EmitSLEB128IntValue(LineDelta);
998 LineSectionSize += 1 + getSLEB128Size(LineDelta);
999 }
1000 if (AddressDelta) {
1001 MS->EmitIntValue(dwarf::DW_LNS_advance_pc, 1);
1002 MS->EmitULEB128IntValue(AddressDelta);
1003 LineSectionSize += 1 + getULEB128Size(AddressDelta);
1004 }
1005 MCDwarfLineAddr::Encode(*MC, Params, INT64_MAX, 0, EncodingOS);
1006 MS->EmitBytes(EncodingOS.str());
1007 LineSectionSize += EncodingBuffer.size();
1008 EncodingBuffer.resize(0);
1009 Address = -1ULL;
1010 LastLine = FileNum = IsStatement = 1;
1011 RowsSinceLastSequence = Column = Isa = 0;
1012 }
1013 }
1014
1015 if (RowsSinceLastSequence) {
1016 MCDwarfLineAddr::Encode(*MC, Params, INT64_MAX, 0, EncodingOS);
1017 MS->EmitBytes(EncodingOS.str());
1018 LineSectionSize += EncodingBuffer.size();
1019 EncodingBuffer.resize(0);
1020 }
1021
1022 MS->EmitLabel(LineEndSym);
1023 }
1024
1025 /// \brief Emit the pubnames or pubtypes section contribution for \p
1026 /// Unit into \p Sec. The data is provided in \p Names.
emitPubSectionForUnit(MCSection * Sec,StringRef SecName,const CompileUnit & Unit,const std::vector<CompileUnit::AccelInfo> & Names)1027 void DwarfStreamer::emitPubSectionForUnit(
1028 MCSection *Sec, StringRef SecName, const CompileUnit &Unit,
1029 const std::vector<CompileUnit::AccelInfo> &Names) {
1030 if (Names.empty())
1031 return;
1032
1033 // Start the dwarf pubnames section.
1034 Asm->OutStreamer->SwitchSection(Sec);
1035 MCSymbol *BeginLabel = Asm->createTempSymbol("pub" + SecName + "_begin");
1036 MCSymbol *EndLabel = Asm->createTempSymbol("pub" + SecName + "_end");
1037
1038 bool HeaderEmitted = false;
1039 // Emit the pubnames for this compilation unit.
1040 for (const auto &Name : Names) {
1041 if (Name.SkipPubSection)
1042 continue;
1043
1044 if (!HeaderEmitted) {
1045 // Emit the header.
1046 Asm->EmitLabelDifference(EndLabel, BeginLabel, 4); // Length
1047 Asm->OutStreamer->EmitLabel(BeginLabel);
1048 Asm->EmitInt16(dwarf::DW_PUBNAMES_VERSION); // Version
1049 Asm->EmitInt32(Unit.getStartOffset()); // Unit offset
1050 Asm->EmitInt32(Unit.getNextUnitOffset() - Unit.getStartOffset()); // Size
1051 HeaderEmitted = true;
1052 }
1053 Asm->EmitInt32(Name.Die->getOffset());
1054 Asm->OutStreamer->EmitBytes(
1055 StringRef(Name.Name.data(), Name.Name.size() + 1));
1056 }
1057
1058 if (!HeaderEmitted)
1059 return;
1060 Asm->EmitInt32(0); // End marker.
1061 Asm->OutStreamer->EmitLabel(EndLabel);
1062 }
1063
1064 /// \brief Emit .debug_pubnames for \p Unit.
emitPubNamesForUnit(const CompileUnit & Unit)1065 void DwarfStreamer::emitPubNamesForUnit(const CompileUnit &Unit) {
1066 emitPubSectionForUnit(MC->getObjectFileInfo()->getDwarfPubNamesSection(),
1067 "names", Unit, Unit.getPubnames());
1068 }
1069
1070 /// \brief Emit .debug_pubtypes for \p Unit.
emitPubTypesForUnit(const CompileUnit & Unit)1071 void DwarfStreamer::emitPubTypesForUnit(const CompileUnit &Unit) {
1072 emitPubSectionForUnit(MC->getObjectFileInfo()->getDwarfPubTypesSection(),
1073 "types", Unit, Unit.getPubtypes());
1074 }
1075
1076 /// \brief Emit a CIE into the debug_frame section.
emitCIE(StringRef CIEBytes)1077 void DwarfStreamer::emitCIE(StringRef CIEBytes) {
1078 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfFrameSection());
1079
1080 MS->EmitBytes(CIEBytes);
1081 FrameSectionSize += CIEBytes.size();
1082 }
1083
1084 /// \brief Emit a FDE into the debug_frame section. \p FDEBytes
1085 /// contains the FDE data without the length, CIE offset and address
1086 /// which will be replaced with the paramter values.
emitFDE(uint32_t CIEOffset,uint32_t AddrSize,uint32_t Address,StringRef FDEBytes)1087 void DwarfStreamer::emitFDE(uint32_t CIEOffset, uint32_t AddrSize,
1088 uint32_t Address, StringRef FDEBytes) {
1089 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfFrameSection());
1090
1091 MS->EmitIntValue(FDEBytes.size() + 4 + AddrSize, 4);
1092 MS->EmitIntValue(CIEOffset, 4);
1093 MS->EmitIntValue(Address, AddrSize);
1094 MS->EmitBytes(FDEBytes);
1095 FrameSectionSize += FDEBytes.size() + 8 + AddrSize;
1096 }
1097
1098 /// \brief The core of the Dwarf linking logic.
1099 ///
1100 /// The link of the dwarf information from the object files will be
1101 /// driven by the selection of 'root DIEs', which are DIEs that
1102 /// describe variables or functions that are present in the linked
1103 /// binary (and thus have entries in the debug map). All the debug
1104 /// information that will be linked (the DIEs, but also the line
1105 /// tables, ranges, ...) is derived from that set of root DIEs.
1106 ///
1107 /// The root DIEs are identified because they contain relocations that
1108 /// correspond to a debug map entry at specific places (the low_pc for
1109 /// a function, the location for a variable). These relocations are
1110 /// called ValidRelocs in the DwarfLinker and are gathered as a very
1111 /// first step when we start processing a DebugMapObject.
1112 class DwarfLinker {
1113 public:
DwarfLinker(StringRef OutputFilename,const LinkOptions & Options)1114 DwarfLinker(StringRef OutputFilename, const LinkOptions &Options)
1115 : OutputFilename(OutputFilename), Options(Options),
1116 BinHolder(Options.Verbose), LastCIEOffset(0) {}
1117
1118 /// \brief Link the contents of the DebugMap.
1119 bool link(const DebugMap &);
1120
1121 void reportWarning(const Twine &Warning, const DWARFUnit *Unit = nullptr,
1122 const DWARFDebugInfoEntryMinimal *DIE = nullptr) const;
1123
1124 private:
1125 /// \brief Called at the start of a debug object link.
1126 void startDebugObject(DWARFContext &, DebugMapObject &);
1127
1128 /// \brief Called at the end of a debug object link.
1129 void endDebugObject();
1130
1131 /// Keeps track of relocations.
1132 class RelocationManager {
1133 struct ValidReloc {
1134 uint32_t Offset;
1135 uint32_t Size;
1136 uint64_t Addend;
1137 const DebugMapObject::DebugMapEntry *Mapping;
1138
ValidRelocllvm::dsymutil::__anon1f629b1b0111::DwarfLinker::RelocationManager::ValidReloc1139 ValidReloc(uint32_t Offset, uint32_t Size, uint64_t Addend,
1140 const DebugMapObject::DebugMapEntry *Mapping)
1141 : Offset(Offset), Size(Size), Addend(Addend), Mapping(Mapping) {}
1142
operator <llvm::dsymutil::__anon1f629b1b0111::DwarfLinker::RelocationManager::ValidReloc1143 bool operator<(const ValidReloc &RHS) const {
1144 return Offset < RHS.Offset;
1145 }
1146 };
1147
1148 DwarfLinker &Linker;
1149
1150 /// \brief The valid relocations for the current DebugMapObject.
1151 /// This vector is sorted by relocation offset.
1152 std::vector<ValidReloc> ValidRelocs;
1153
1154 /// \brief Index into ValidRelocs of the next relocation to
1155 /// consider. As we walk the DIEs in acsending file offset and as
1156 /// ValidRelocs is sorted by file offset, keeping this index
1157 /// uptodate is all we have to do to have a cheap lookup during the
1158 /// root DIE selection and during DIE cloning.
1159 unsigned NextValidReloc;
1160
1161 public:
RelocationManager(DwarfLinker & Linker)1162 RelocationManager(DwarfLinker &Linker)
1163 : Linker(Linker), NextValidReloc(0) {}
1164
hasValidRelocs() const1165 bool hasValidRelocs() const { return !ValidRelocs.empty(); }
1166 /// \brief Reset the NextValidReloc counter.
resetValidRelocs()1167 void resetValidRelocs() { NextValidReloc = 0; }
1168
1169 /// \defgroup FindValidRelocations Translate debug map into a list
1170 /// of relevant relocations
1171 ///
1172 /// @{
1173 bool findValidRelocsInDebugInfo(const object::ObjectFile &Obj,
1174 const DebugMapObject &DMO);
1175
1176 bool findValidRelocs(const object::SectionRef &Section,
1177 const object::ObjectFile &Obj,
1178 const DebugMapObject &DMO);
1179
1180 void findValidRelocsMachO(const object::SectionRef &Section,
1181 const object::MachOObjectFile &Obj,
1182 const DebugMapObject &DMO);
1183 /// @}
1184
1185 bool hasValidRelocation(uint32_t StartOffset, uint32_t EndOffset,
1186 CompileUnit::DIEInfo &Info);
1187
1188 bool applyValidRelocs(MutableArrayRef<char> Data, uint32_t BaseOffset,
1189 bool isLittleEndian);
1190 };
1191
1192 /// \defgroup FindRootDIEs Find DIEs corresponding to debug map entries.
1193 ///
1194 /// @{
1195 /// \brief Recursively walk the \p DIE tree and look for DIEs to
1196 /// keep. Store that information in \p CU's DIEInfo.
1197 void lookForDIEsToKeep(RelocationManager &RelocMgr,
1198 const DWARFDebugInfoEntryMinimal &DIE,
1199 const DebugMapObject &DMO, CompileUnit &CU,
1200 unsigned Flags);
1201
1202 /// If this compile unit is really a skeleton CU that points to a
1203 /// clang module, register it in ClangModules and return true.
1204 ///
1205 /// A skeleton CU is a CU without children, a DW_AT_gnu_dwo_name
1206 /// pointing to the module, and a DW_AT_gnu_dwo_id with the module
1207 /// hash.
1208 bool registerModuleReference(const DWARFDebugInfoEntryMinimal &CUDie,
1209 const DWARFUnit &Unit, DebugMap &ModuleMap,
1210 unsigned Indent = 0);
1211
1212 /// Recursively add the debug info in this clang module .pcm
1213 /// file (and all the modules imported by it in a bottom-up fashion)
1214 /// to Units.
1215 void loadClangModule(StringRef Filename, StringRef ModulePath,
1216 StringRef ModuleName, uint64_t DwoId,
1217 DebugMap &ModuleMap, unsigned Indent = 0);
1218
1219 /// \brief Flags passed to DwarfLinker::lookForDIEsToKeep
1220 enum TravesalFlags {
1221 TF_Keep = 1 << 0, ///< Mark the traversed DIEs as kept.
1222 TF_InFunctionScope = 1 << 1, ///< Current scope is a fucntion scope.
1223 TF_DependencyWalk = 1 << 2, ///< Walking the dependencies of a kept DIE.
1224 TF_ParentWalk = 1 << 3, ///< Walking up the parents of a kept DIE.
1225 TF_ODR = 1 << 4, ///< Use the ODR whhile keeping dependants.
1226 TF_SkipPC = 1 << 5, ///< Skip all location attributes.
1227 };
1228
1229 /// \brief Mark the passed DIE as well as all the ones it depends on
1230 /// as kept.
1231 void keepDIEAndDependencies(RelocationManager &RelocMgr,
1232 const DWARFDebugInfoEntryMinimal &DIE,
1233 CompileUnit::DIEInfo &MyInfo,
1234 const DebugMapObject &DMO, CompileUnit &CU,
1235 bool UseODR);
1236
1237 unsigned shouldKeepDIE(RelocationManager &RelocMgr,
1238 const DWARFDebugInfoEntryMinimal &DIE,
1239 CompileUnit &Unit, CompileUnit::DIEInfo &MyInfo,
1240 unsigned Flags);
1241
1242 unsigned shouldKeepVariableDIE(RelocationManager &RelocMgr,
1243 const DWARFDebugInfoEntryMinimal &DIE,
1244 CompileUnit &Unit,
1245 CompileUnit::DIEInfo &MyInfo, unsigned Flags);
1246
1247 unsigned shouldKeepSubprogramDIE(RelocationManager &RelocMgr,
1248 const DWARFDebugInfoEntryMinimal &DIE,
1249 CompileUnit &Unit,
1250 CompileUnit::DIEInfo &MyInfo,
1251 unsigned Flags);
1252
1253 bool hasValidRelocation(uint32_t StartOffset, uint32_t EndOffset,
1254 CompileUnit::DIEInfo &Info);
1255 /// @}
1256
1257 /// \defgroup Linking Methods used to link the debug information
1258 ///
1259 /// @{
1260
1261 class DIECloner {
1262 DwarfLinker &Linker;
1263 RelocationManager &RelocMgr;
1264 /// Allocator used for all the DIEValue objects.
1265 BumpPtrAllocator &DIEAlloc;
1266 MutableArrayRef<CompileUnit> CompileUnits;
1267 LinkOptions Options;
1268
1269 public:
DIECloner(DwarfLinker & Linker,RelocationManager & RelocMgr,BumpPtrAllocator & DIEAlloc,MutableArrayRef<CompileUnit> CompileUnits,LinkOptions & Options)1270 DIECloner(DwarfLinker &Linker, RelocationManager &RelocMgr,
1271 BumpPtrAllocator &DIEAlloc,
1272 MutableArrayRef<CompileUnit> CompileUnits, LinkOptions &Options)
1273 : Linker(Linker), RelocMgr(RelocMgr), DIEAlloc(DIEAlloc),
1274 CompileUnits(CompileUnits), Options(Options) {}
1275
1276 /// Recursively clone \p InputDIE into an tree of DIE objects
1277 /// where useless (as decided by lookForDIEsToKeep()) bits have been
1278 /// stripped out and addresses have been rewritten according to the
1279 /// debug map.
1280 ///
1281 /// \param OutOffset is the offset the cloned DIE in the output
1282 /// compile unit.
1283 /// \param PCOffset (while cloning a function scope) is the offset
1284 /// applied to the entry point of the function to get the linked address.
1285 ///
1286 /// \returns the root of the cloned tree or null if nothing was selected.
1287 DIE *cloneDIE(const DWARFDebugInfoEntryMinimal &InputDIE, CompileUnit &U,
1288 int64_t PCOffset, uint32_t OutOffset, unsigned Flags);
1289
1290 /// Construct the output DIE tree by cloning the DIEs we
1291 /// chose to keep above. If there are no valid relocs, then there's
1292 /// nothing to clone/emit.
1293 void cloneAllCompileUnits(DWARFContextInMemory &DwarfContext);
1294
1295 private:
1296 typedef DWARFAbbreviationDeclaration::AttributeSpec AttributeSpec;
1297
1298 /// Information gathered and exchanged between the various
1299 /// clone*Attributes helpers about the attributes of a particular DIE.
1300 struct AttributesInfo {
1301 const char *Name, *MangledName; ///< Names.
1302 uint32_t NameOffset, MangledNameOffset; ///< Offsets in the string pool.
1303
1304 uint64_t OrigLowPc; ///< Value of AT_low_pc in the input DIE
1305 uint64_t OrigHighPc; ///< Value of AT_high_pc in the input DIE
1306 int64_t PCOffset; ///< Offset to apply to PC addresses inside a function.
1307
1308 bool HasLowPc; ///< Does the DIE have a low_pc attribute?
1309 bool IsDeclaration; ///< Is this DIE only a declaration?
1310
AttributesInfollvm::dsymutil::__anon1f629b1b0111::DwarfLinker::DIECloner::AttributesInfo1311 AttributesInfo()
1312 : Name(nullptr), MangledName(nullptr), NameOffset(0),
1313 MangledNameOffset(0), OrigLowPc(UINT64_MAX), OrigHighPc(0),
1314 PCOffset(0), HasLowPc(false), IsDeclaration(false) {}
1315 };
1316
1317 /// Helper for cloneDIE.
1318 unsigned cloneAttribute(DIE &Die,
1319 const DWARFDebugInfoEntryMinimal &InputDIE,
1320 CompileUnit &U, const DWARFFormValue &Val,
1321 const AttributeSpec AttrSpec, unsigned AttrSize,
1322 AttributesInfo &AttrInfo);
1323
1324 /// Clone a string attribute described by \p AttrSpec and add
1325 /// it to \p Die.
1326 /// \returns the size of the new attribute.
1327 unsigned cloneStringAttribute(DIE &Die, AttributeSpec AttrSpec,
1328 const DWARFFormValue &Val,
1329 const DWARFUnit &U);
1330
1331 /// Clone an attribute referencing another DIE and add
1332 /// it to \p Die.
1333 /// \returns the size of the new attribute.
1334 unsigned
1335 cloneDieReferenceAttribute(DIE &Die,
1336 const DWARFDebugInfoEntryMinimal &InputDIE,
1337 AttributeSpec AttrSpec, unsigned AttrSize,
1338 const DWARFFormValue &Val, CompileUnit &Unit);
1339
1340 /// Clone an attribute referencing another DIE and add
1341 /// it to \p Die.
1342 /// \returns the size of the new attribute.
1343 unsigned cloneBlockAttribute(DIE &Die, AttributeSpec AttrSpec,
1344 const DWARFFormValue &Val, unsigned AttrSize);
1345
1346 /// Clone an attribute referencing another DIE and add
1347 /// it to \p Die.
1348 /// \returns the size of the new attribute.
1349 unsigned cloneAddressAttribute(DIE &Die, AttributeSpec AttrSpec,
1350 const DWARFFormValue &Val,
1351 const CompileUnit &Unit,
1352 AttributesInfo &Info);
1353
1354 /// Clone a scalar attribute and add it to \p Die.
1355 /// \returns the size of the new attribute.
1356 unsigned cloneScalarAttribute(DIE &Die,
1357 const DWARFDebugInfoEntryMinimal &InputDIE,
1358 CompileUnit &U, AttributeSpec AttrSpec,
1359 const DWARFFormValue &Val, unsigned AttrSize,
1360 AttributesInfo &Info);
1361
1362 /// Get the potential name and mangled name for the entity
1363 /// described by \p Die and store them in \Info if they are not
1364 /// already there.
1365 /// \returns is a name was found.
1366 bool getDIENames(const DWARFDebugInfoEntryMinimal &Die, DWARFUnit &U,
1367 AttributesInfo &Info);
1368
1369 /// Create a copy of abbreviation Abbrev.
1370 void copyAbbrev(const DWARFAbbreviationDeclaration &Abbrev, bool hasODR);
1371 };
1372
1373 /// \brief Assign an abbreviation number to \p Abbrev
1374 void AssignAbbrev(DIEAbbrev &Abbrev);
1375
1376 /// \brief FoldingSet that uniques the abbreviations.
1377 FoldingSet<DIEAbbrev> AbbreviationsSet;
1378 /// \brief Storage for the unique Abbreviations.
1379 /// This is passed to AsmPrinter::emitDwarfAbbrevs(), thus it cannot
1380 /// be changed to a vecot of unique_ptrs.
1381 std::vector<std::unique_ptr<DIEAbbrev>> Abbreviations;
1382
1383 /// \brief Compute and emit debug_ranges section for \p Unit, and
1384 /// patch the attributes referencing it.
1385 void patchRangesForUnit(const CompileUnit &Unit, DWARFContext &Dwarf) const;
1386
1387 /// \brief Generate and emit the DW_AT_ranges attribute for a
1388 /// compile_unit if it had one.
1389 void generateUnitRanges(CompileUnit &Unit) const;
1390
1391 /// \brief Extract the line tables fromt he original dwarf, extract
1392 /// the relevant parts according to the linked function ranges and
1393 /// emit the result in the debug_line section.
1394 void patchLineTableForUnit(CompileUnit &Unit, DWARFContext &OrigDwarf);
1395
1396 /// \brief Emit the accelerator entries for \p Unit.
1397 void emitAcceleratorEntriesForUnit(CompileUnit &Unit);
1398
1399 /// \brief Patch the frame info for an object file and emit it.
1400 void patchFrameInfoForObject(const DebugMapObject &, DWARFContext &,
1401 unsigned AddressSize);
1402
1403 /// \brief DIELoc objects that need to be destructed (but not freed!).
1404 std::vector<DIELoc *> DIELocs;
1405 /// \brief DIEBlock objects that need to be destructed (but not freed!).
1406 std::vector<DIEBlock *> DIEBlocks;
1407 /// \brief Allocator used for all the DIEValue objects.
1408 BumpPtrAllocator DIEAlloc;
1409 /// @}
1410
1411 /// ODR Contexts for that link.
1412 DeclContextTree ODRContexts;
1413
1414 /// \defgroup Helpers Various helper methods.
1415 ///
1416 /// @{
1417 bool createStreamer(Triple TheTriple, StringRef OutputFilename);
1418
1419 /// \brief Attempt to load a debug object from disk.
1420 ErrorOr<const object::ObjectFile &> loadObject(BinaryHolder &BinaryHolder,
1421 DebugMapObject &Obj,
1422 const DebugMap &Map);
1423 /// @}
1424
1425 std::string OutputFilename;
1426 LinkOptions Options;
1427 BinaryHolder BinHolder;
1428 std::unique_ptr<DwarfStreamer> Streamer;
1429 uint64_t OutputDebugInfoSize;
1430 unsigned UnitID; ///< A unique ID that identifies each compile unit.
1431
1432 /// The units of the current debug map object.
1433 std::vector<CompileUnit> Units;
1434
1435 /// The debug map object currently under consideration.
1436 DebugMapObject *CurrentDebugObject;
1437
1438 /// \brief The Dwarf string pool
1439 NonRelocatableStringpool StringPool;
1440
1441 /// \brief This map is keyed by the entry PC of functions in that
1442 /// debug object and the associated value is a pair storing the
1443 /// corresponding end PC and the offset to apply to get the linked
1444 /// address.
1445 ///
1446 /// See startDebugObject() for a more complete description of its use.
1447 std::map<uint64_t, std::pair<uint64_t, int64_t>> Ranges;
1448
1449 /// \brief The CIEs that have been emitted in the output
1450 /// section. The actual CIE data serves a the key to this StringMap,
1451 /// this takes care of comparing the semantics of CIEs defined in
1452 /// different object files.
1453 StringMap<uint32_t> EmittedCIEs;
1454
1455 /// Offset of the last CIE that has been emitted in the output
1456 /// debug_frame section.
1457 uint32_t LastCIEOffset;
1458
1459 /// Mapping the PCM filename to the DwoId.
1460 StringMap<uint64_t> ClangModules;
1461 };
1462
1463 /// Similar to DWARFUnitSection::getUnitForOffset(), but returning our
1464 /// CompileUnit object instead.
getUnitForOffset(MutableArrayRef<CompileUnit> Units,unsigned Offset)1465 static CompileUnit *getUnitForOffset(MutableArrayRef<CompileUnit> Units,
1466 unsigned Offset) {
1467 auto CU =
1468 std::upper_bound(Units.begin(), Units.end(), Offset,
1469 [](uint32_t LHS, const CompileUnit &RHS) {
1470 return LHS < RHS.getOrigUnit().getNextUnitOffset();
1471 });
1472 return CU != Units.end() ? &*CU : nullptr;
1473 }
1474
1475 /// Resolve the DIE attribute reference that has been
1476 /// extracted in \p RefValue. The resulting DIE migh be in another
1477 /// CompileUnit which is stored into \p ReferencedCU.
1478 /// \returns null if resolving fails for any reason.
resolveDIEReference(const DwarfLinker & Linker,MutableArrayRef<CompileUnit> Units,const DWARFFormValue & RefValue,const DWARFUnit & Unit,const DWARFDebugInfoEntryMinimal & DIE,CompileUnit * & RefCU)1479 static const DWARFDebugInfoEntryMinimal *resolveDIEReference(
1480 const DwarfLinker &Linker, MutableArrayRef<CompileUnit> Units,
1481 const DWARFFormValue &RefValue, const DWARFUnit &Unit,
1482 const DWARFDebugInfoEntryMinimal &DIE, CompileUnit *&RefCU) {
1483 assert(RefValue.isFormClass(DWARFFormValue::FC_Reference));
1484 uint64_t RefOffset = *RefValue.getAsReference(&Unit);
1485
1486 if ((RefCU = getUnitForOffset(Units, RefOffset)))
1487 if (const auto *RefDie = RefCU->getOrigUnit().getDIEForOffset(RefOffset))
1488 return RefDie;
1489
1490 Linker.reportWarning("could not find referenced DIE", &Unit, &DIE);
1491 return nullptr;
1492 }
1493
1494 /// \returns whether the passed \a Attr type might contain a DIE
1495 /// reference suitable for ODR uniquing.
isODRAttribute(uint16_t Attr)1496 static bool isODRAttribute(uint16_t Attr) {
1497 switch (Attr) {
1498 default:
1499 return false;
1500 case dwarf::DW_AT_type:
1501 case dwarf::DW_AT_containing_type:
1502 case dwarf::DW_AT_specification:
1503 case dwarf::DW_AT_abstract_origin:
1504 case dwarf::DW_AT_import:
1505 return true;
1506 }
1507 llvm_unreachable("Improper attribute.");
1508 }
1509
1510 /// Set the last DIE/CU a context was seen in and, possibly invalidate
1511 /// the context if it is ambiguous.
1512 ///
1513 /// In the current implementation, we don't handle overloaded
1514 /// functions well, because the argument types are not taken into
1515 /// account when computing the DeclContext tree.
1516 ///
1517 /// Some of this is mitigated byt using mangled names that do contain
1518 /// the arguments types, but sometimes (eg. with function templates)
1519 /// we don't have that. In that case, just do not unique anything that
1520 /// refers to the contexts we are not able to distinguish.
1521 ///
1522 /// If a context that is not a namespace appears twice in the same CU,
1523 /// we know it is ambiguous. Make it invalid.
setLastSeenDIE(CompileUnit & U,const DWARFDebugInfoEntryMinimal * Die)1524 bool DeclContext::setLastSeenDIE(CompileUnit &U,
1525 const DWARFDebugInfoEntryMinimal *Die) {
1526 if (LastSeenCompileUnitID == U.getUniqueID()) {
1527 DWARFUnit &OrigUnit = U.getOrigUnit();
1528 uint32_t FirstIdx = OrigUnit.getDIEIndex(LastSeenDIE);
1529 U.getInfo(FirstIdx).Ctxt = nullptr;
1530 return false;
1531 }
1532
1533 LastSeenCompileUnitID = U.getUniqueID();
1534 LastSeenDIE = Die;
1535 return true;
1536 }
1537
getChildDeclContext(DeclContext & Context,const DWARFDebugInfoEntryMinimal * DIE,CompileUnit & U,NonRelocatableStringpool & StringPool,bool InClangModule)1538 PointerIntPair<DeclContext *, 1> DeclContextTree::getChildDeclContext(
1539 DeclContext &Context, const DWARFDebugInfoEntryMinimal *DIE, CompileUnit &U,
1540 NonRelocatableStringpool &StringPool, bool InClangModule) {
1541 unsigned Tag = DIE->getTag();
1542
1543 // FIXME: dsymutil-classic compat: We should bail out here if we
1544 // have a specification or an abstract_origin. We will get the
1545 // parent context wrong here.
1546
1547 switch (Tag) {
1548 default:
1549 // By default stop gathering child contexts.
1550 return PointerIntPair<DeclContext *, 1>(nullptr);
1551 case dwarf::DW_TAG_module:
1552 break;
1553 case dwarf::DW_TAG_compile_unit:
1554 return PointerIntPair<DeclContext *, 1>(&Context);
1555 case dwarf::DW_TAG_subprogram:
1556 // Do not unique anything inside CU local functions.
1557 if ((Context.getTag() == dwarf::DW_TAG_namespace ||
1558 Context.getTag() == dwarf::DW_TAG_compile_unit) &&
1559 !DIE->getAttributeValueAsUnsignedConstant(&U.getOrigUnit(),
1560 dwarf::DW_AT_external, 0))
1561 return PointerIntPair<DeclContext *, 1>(nullptr);
1562 // Fallthrough
1563 case dwarf::DW_TAG_member:
1564 case dwarf::DW_TAG_namespace:
1565 case dwarf::DW_TAG_structure_type:
1566 case dwarf::DW_TAG_class_type:
1567 case dwarf::DW_TAG_union_type:
1568 case dwarf::DW_TAG_enumeration_type:
1569 case dwarf::DW_TAG_typedef:
1570 // Artificial things might be ambiguous, because they might be
1571 // created on demand. For example implicitely defined constructors
1572 // are ambiguous because of the way we identify contexts, and they
1573 // won't be generated everytime everywhere.
1574 if (DIE->getAttributeValueAsUnsignedConstant(&U.getOrigUnit(),
1575 dwarf::DW_AT_artificial, 0))
1576 return PointerIntPair<DeclContext *, 1>(nullptr);
1577 break;
1578 }
1579
1580 const char *Name = DIE->getName(&U.getOrigUnit(), DINameKind::LinkageName);
1581 const char *ShortName = DIE->getName(&U.getOrigUnit(), DINameKind::ShortName);
1582 StringRef NameRef;
1583 StringRef ShortNameRef;
1584 StringRef FileRef;
1585
1586 if (Name)
1587 NameRef = StringPool.internString(Name);
1588 else if (Tag == dwarf::DW_TAG_namespace)
1589 // FIXME: For dsymutil-classic compatibility. I think uniquing
1590 // within anonymous namespaces is wrong. There is no ODR guarantee
1591 // there.
1592 NameRef = StringPool.internString("(anonymous namespace)");
1593
1594 if (ShortName && ShortName != Name)
1595 ShortNameRef = StringPool.internString(ShortName);
1596 else
1597 ShortNameRef = NameRef;
1598
1599 if (Tag != dwarf::DW_TAG_class_type && Tag != dwarf::DW_TAG_structure_type &&
1600 Tag != dwarf::DW_TAG_union_type &&
1601 Tag != dwarf::DW_TAG_enumeration_type && NameRef.empty())
1602 return PointerIntPair<DeclContext *, 1>(nullptr);
1603
1604 std::string File;
1605 unsigned Line = 0;
1606 unsigned ByteSize = UINT32_MAX;
1607
1608 if (!InClangModule) {
1609 // Gather some discriminating data about the DeclContext we will be
1610 // creating: File, line number and byte size. This shouldn't be
1611 // necessary, because the ODR is just about names, but given that we
1612 // do some approximations with overloaded functions and anonymous
1613 // namespaces, use these additional data points to make the process
1614 // safer. This is disabled for clang modules, because forward
1615 // declarations of module-defined types do not have a file and line.
1616 ByteSize = DIE->getAttributeValueAsUnsignedConstant(
1617 &U.getOrigUnit(), dwarf::DW_AT_byte_size, UINT64_MAX);
1618 if (Tag != dwarf::DW_TAG_namespace || !Name) {
1619 if (unsigned FileNum = DIE->getAttributeValueAsUnsignedConstant(
1620 &U.getOrigUnit(), dwarf::DW_AT_decl_file, 0)) {
1621 if (const auto *LT = U.getOrigUnit().getContext().getLineTableForUnit(
1622 &U.getOrigUnit())) {
1623 // FIXME: dsymutil-classic compatibility. I'd rather not
1624 // unique anything in anonymous namespaces, but if we do, then
1625 // verify that the file and line correspond.
1626 if (!Name && Tag == dwarf::DW_TAG_namespace)
1627 FileNum = 1;
1628
1629 // FIXME: Passing U.getOrigUnit().getCompilationDir()
1630 // instead of "" would allow more uniquing, but for now, do
1631 // it this way to match dsymutil-classic.
1632 if (LT->getFileNameByIndex(
1633 FileNum, "",
1634 DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath,
1635 File)) {
1636 Line = DIE->getAttributeValueAsUnsignedConstant(
1637 &U.getOrigUnit(), dwarf::DW_AT_decl_line, 0);
1638 #ifdef HAVE_REALPATH
1639 // Cache the resolved paths, because calling realpath is expansive.
1640 if (const char *ResolvedPath = U.getResolvedPath(FileNum)) {
1641 File = ResolvedPath;
1642 } else {
1643 char RealPath[PATH_MAX + 1];
1644 RealPath[PATH_MAX] = 0;
1645 if (::realpath(File.c_str(), RealPath))
1646 File = RealPath;
1647 U.setResolvedPath(FileNum, File);
1648 }
1649 #endif
1650 FileRef = StringPool.internString(File);
1651 }
1652 }
1653 }
1654 }
1655 }
1656
1657 if (!Line && NameRef.empty())
1658 return PointerIntPair<DeclContext *, 1>(nullptr);
1659
1660 // We hash NameRef, which is the mangled name, in order to get most
1661 // overloaded functions resolve correctly.
1662 //
1663 // Strictly speaking, hashing the Tag is only necessary for a
1664 // DW_TAG_module, to prevent uniquing of a module and a namespace
1665 // with the same name.
1666 //
1667 // FIXME: dsymutil-classic won't unique the same type presented
1668 // once as a struct and once as a class. Using the Tag in the fully
1669 // qualified name hash to get the same effect.
1670 unsigned Hash = hash_combine(Context.getQualifiedNameHash(), Tag, NameRef);
1671
1672 // FIXME: dsymutil-classic compatibility: when we don't have a name,
1673 // use the filename.
1674 if (Tag == dwarf::DW_TAG_namespace && NameRef == "(anonymous namespace)")
1675 Hash = hash_combine(Hash, FileRef);
1676
1677 // Now look if this context already exists.
1678 DeclContext Key(Hash, Line, ByteSize, Tag, NameRef, FileRef, Context);
1679 auto ContextIter = Contexts.find(&Key);
1680
1681 if (ContextIter == Contexts.end()) {
1682 // The context wasn't found.
1683 bool Inserted;
1684 DeclContext *NewContext =
1685 new (Allocator) DeclContext(Hash, Line, ByteSize, Tag, NameRef, FileRef,
1686 Context, DIE, U.getUniqueID());
1687 std::tie(ContextIter, Inserted) = Contexts.insert(NewContext);
1688 assert(Inserted && "Failed to insert DeclContext");
1689 (void)Inserted;
1690 } else if (Tag != dwarf::DW_TAG_namespace &&
1691 !(*ContextIter)->setLastSeenDIE(U, DIE)) {
1692 // The context was found, but it is ambiguous with another context
1693 // in the same file. Mark it invalid.
1694 return PointerIntPair<DeclContext *, 1>(*ContextIter, /* Invalid= */ 1);
1695 }
1696
1697 assert(ContextIter != Contexts.end());
1698 // FIXME: dsymutil-classic compatibility. Union types aren't
1699 // uniques, but their children might be.
1700 if ((Tag == dwarf::DW_TAG_subprogram &&
1701 Context.getTag() != dwarf::DW_TAG_structure_type &&
1702 Context.getTag() != dwarf::DW_TAG_class_type) ||
1703 (Tag == dwarf::DW_TAG_union_type))
1704 return PointerIntPair<DeclContext *, 1>(*ContextIter, /* Invalid= */ 1);
1705
1706 return PointerIntPair<DeclContext *, 1>(*ContextIter);
1707 }
1708
getDIENames(const DWARFDebugInfoEntryMinimal & Die,DWARFUnit & U,AttributesInfo & Info)1709 bool DwarfLinker::DIECloner::getDIENames(const DWARFDebugInfoEntryMinimal &Die,
1710 DWARFUnit &U, AttributesInfo &Info) {
1711 // FIXME: a bit wasteful as the first getName might return the
1712 // short name.
1713 if (!Info.MangledName &&
1714 (Info.MangledName = Die.getName(&U, DINameKind::LinkageName)))
1715 Info.MangledNameOffset =
1716 Linker.StringPool.getStringOffset(Info.MangledName);
1717
1718 if (!Info.Name && (Info.Name = Die.getName(&U, DINameKind::ShortName)))
1719 Info.NameOffset = Linker.StringPool.getStringOffset(Info.Name);
1720
1721 return Info.Name || Info.MangledName;
1722 }
1723
1724 /// \brief Report a warning to the user, optionaly including
1725 /// information about a specific \p DIE related to the warning.
reportWarning(const Twine & Warning,const DWARFUnit * Unit,const DWARFDebugInfoEntryMinimal * DIE) const1726 void DwarfLinker::reportWarning(const Twine &Warning, const DWARFUnit *Unit,
1727 const DWARFDebugInfoEntryMinimal *DIE) const {
1728 StringRef Context = "<debug map>";
1729 if (CurrentDebugObject)
1730 Context = CurrentDebugObject->getObjectFilename();
1731 warn(Warning, Context);
1732
1733 if (!Options.Verbose || !DIE)
1734 return;
1735
1736 errs() << " in DIE:\n";
1737 DIE->dump(errs(), const_cast<DWARFUnit *>(Unit), 0 /* RecurseDepth */,
1738 6 /* Indent */);
1739 }
1740
createStreamer(Triple TheTriple,StringRef OutputFilename)1741 bool DwarfLinker::createStreamer(Triple TheTriple, StringRef OutputFilename) {
1742 if (Options.NoOutput)
1743 return true;
1744
1745 Streamer = llvm::make_unique<DwarfStreamer>();
1746 return Streamer->init(TheTriple, OutputFilename);
1747 }
1748
1749 /// Recursive helper to build the global DeclContext information and
1750 /// gather the child->parent relationships in the original compile unit.
1751 ///
1752 /// \return true when this DIE and all of its children are only
1753 /// forward declarations to types defined in external clang modules
1754 /// (i.e., forward declarations that are children of a DW_TAG_module).
analyzeContextInfo(const DWARFDebugInfoEntryMinimal * DIE,unsigned ParentIdx,CompileUnit & CU,DeclContext * CurrentDeclContext,NonRelocatableStringpool & StringPool,DeclContextTree & Contexts,bool InImportedModule=false)1755 static bool analyzeContextInfo(const DWARFDebugInfoEntryMinimal *DIE,
1756 unsigned ParentIdx, CompileUnit &CU,
1757 DeclContext *CurrentDeclContext,
1758 NonRelocatableStringpool &StringPool,
1759 DeclContextTree &Contexts,
1760 bool InImportedModule = false) {
1761 unsigned MyIdx = CU.getOrigUnit().getDIEIndex(DIE);
1762 CompileUnit::DIEInfo &Info = CU.getInfo(MyIdx);
1763
1764 // Clang imposes an ODR on modules(!) regardless of the language:
1765 // "The module-id should consist of only a single identifier,
1766 // which provides the name of the module being defined. Each
1767 // module shall have a single definition."
1768 //
1769 // This does not extend to the types inside the modules:
1770 // "[I]n C, this implies that if two structs are defined in
1771 // different submodules with the same name, those two types are
1772 // distinct types (but may be compatible types if their
1773 // definitions match)."
1774 //
1775 // We treat non-C++ modules like namespaces for this reason.
1776 if (DIE->getTag() == dwarf::DW_TAG_module && ParentIdx == 0 &&
1777 DIE->getAttributeValueAsString(&CU.getOrigUnit(), dwarf::DW_AT_name,
1778 "") != CU.getClangModuleName()) {
1779 InImportedModule = true;
1780 }
1781
1782 Info.ParentIdx = ParentIdx;
1783 bool InClangModule = CU.isClangModule() || InImportedModule;
1784 if (CU.hasODR() || InClangModule) {
1785 if (CurrentDeclContext) {
1786 auto PtrInvalidPair = Contexts.getChildDeclContext(
1787 *CurrentDeclContext, DIE, CU, StringPool, InClangModule);
1788 CurrentDeclContext = PtrInvalidPair.getPointer();
1789 Info.Ctxt =
1790 PtrInvalidPair.getInt() ? nullptr : PtrInvalidPair.getPointer();
1791 } else
1792 Info.Ctxt = CurrentDeclContext = nullptr;
1793 }
1794
1795 Info.Prune = InImportedModule;
1796 if (DIE->hasChildren())
1797 for (auto *Child = DIE->getFirstChild(); Child && !Child->isNULL();
1798 Child = Child->getSibling())
1799 Info.Prune &= analyzeContextInfo(Child, MyIdx, CU, CurrentDeclContext,
1800 StringPool, Contexts, InImportedModule);
1801
1802 // Prune this DIE if it is either a forward declaration inside a
1803 // DW_TAG_module or a DW_TAG_module that contains nothing but
1804 // forward declarations.
1805 Info.Prune &= (DIE->getTag() == dwarf::DW_TAG_module) ||
1806 DIE->getAttributeValueAsUnsignedConstant(
1807 &CU.getOrigUnit(), dwarf::DW_AT_declaration, 0);
1808
1809 // Don't prune it if there is no definition for the DIE.
1810 Info.Prune &= Info.Ctxt && Info.Ctxt->getCanonicalDIEOffset();
1811
1812 return Info.Prune;
1813 }
1814
dieNeedsChildrenToBeMeaningful(uint32_t Tag)1815 static bool dieNeedsChildrenToBeMeaningful(uint32_t Tag) {
1816 switch (Tag) {
1817 default:
1818 return false;
1819 case dwarf::DW_TAG_subprogram:
1820 case dwarf::DW_TAG_lexical_block:
1821 case dwarf::DW_TAG_subroutine_type:
1822 case dwarf::DW_TAG_structure_type:
1823 case dwarf::DW_TAG_class_type:
1824 case dwarf::DW_TAG_union_type:
1825 return true;
1826 }
1827 llvm_unreachable("Invalid Tag");
1828 }
1829
getRefAddrSize(const DWARFUnit & U)1830 static unsigned getRefAddrSize(const DWARFUnit &U) {
1831 if (U.getVersion() == 2)
1832 return U.getAddressByteSize();
1833 return 4;
1834 }
1835
startDebugObject(DWARFContext & Dwarf,DebugMapObject & Obj)1836 void DwarfLinker::startDebugObject(DWARFContext &Dwarf, DebugMapObject &Obj) {
1837 Units.reserve(Dwarf.getNumCompileUnits());
1838 // Iterate over the debug map entries and put all the ones that are
1839 // functions (because they have a size) into the Ranges map. This
1840 // map is very similar to the FunctionRanges that are stored in each
1841 // unit, with 2 notable differences:
1842 // - obviously this one is global, while the other ones are per-unit.
1843 // - this one contains not only the functions described in the DIE
1844 // tree, but also the ones that are only in the debug map.
1845 // The latter information is required to reproduce dsymutil's logic
1846 // while linking line tables. The cases where this information
1847 // matters look like bugs that need to be investigated, but for now
1848 // we need to reproduce dsymutil's behavior.
1849 // FIXME: Once we understood exactly if that information is needed,
1850 // maybe totally remove this (or try to use it to do a real
1851 // -gline-tables-only on Darwin.
1852 for (const auto &Entry : Obj.symbols()) {
1853 const auto &Mapping = Entry.getValue();
1854 if (Mapping.Size)
1855 Ranges[Mapping.ObjectAddress] = std::make_pair(
1856 Mapping.ObjectAddress + Mapping.Size,
1857 int64_t(Mapping.BinaryAddress) - Mapping.ObjectAddress);
1858 }
1859 }
1860
endDebugObject()1861 void DwarfLinker::endDebugObject() {
1862 Units.clear();
1863 Ranges.clear();
1864
1865 for (auto I = DIEBlocks.begin(), E = DIEBlocks.end(); I != E; ++I)
1866 (*I)->~DIEBlock();
1867 for (auto I = DIELocs.begin(), E = DIELocs.end(); I != E; ++I)
1868 (*I)->~DIELoc();
1869
1870 DIEBlocks.clear();
1871 DIELocs.clear();
1872 DIEAlloc.Reset();
1873 }
1874
1875 /// \brief Iterate over the relocations of the given \p Section and
1876 /// store the ones that correspond to debug map entries into the
1877 /// ValidRelocs array.
1878 void DwarfLinker::RelocationManager::
findValidRelocsMachO(const object::SectionRef & Section,const object::MachOObjectFile & Obj,const DebugMapObject & DMO)1879 findValidRelocsMachO(const object::SectionRef &Section,
1880 const object::MachOObjectFile &Obj,
1881 const DebugMapObject &DMO) {
1882 StringRef Contents;
1883 Section.getContents(Contents);
1884 DataExtractor Data(Contents, Obj.isLittleEndian(), 0);
1885
1886 for (const object::RelocationRef &Reloc : Section.relocations()) {
1887 object::DataRefImpl RelocDataRef = Reloc.getRawDataRefImpl();
1888 MachO::any_relocation_info MachOReloc = Obj.getRelocation(RelocDataRef);
1889 unsigned RelocSize = 1 << Obj.getAnyRelocationLength(MachOReloc);
1890 uint64_t Offset64 = Reloc.getOffset();
1891 if ((RelocSize != 4 && RelocSize != 8)) {
1892 Linker.reportWarning(" unsupported relocation in debug_info section.");
1893 continue;
1894 }
1895 uint32_t Offset = Offset64;
1896 // Mach-o uses REL relocations, the addend is at the relocation offset.
1897 uint64_t Addend = Data.getUnsigned(&Offset, RelocSize);
1898
1899 auto Sym = Reloc.getSymbol();
1900 if (Sym != Obj.symbol_end()) {
1901 ErrorOr<StringRef> SymbolName = Sym->getName();
1902 if (!SymbolName) {
1903 Linker.reportWarning("error getting relocation symbol name.");
1904 continue;
1905 }
1906 if (const auto *Mapping = DMO.lookupSymbol(*SymbolName))
1907 ValidRelocs.emplace_back(Offset64, RelocSize, Addend, Mapping);
1908 } else if (const auto *Mapping = DMO.lookupObjectAddress(Addend)) {
1909 // Do not store the addend. The addend was the address of the
1910 // symbol in the object file, the address in the binary that is
1911 // stored in the debug map doesn't need to be offseted.
1912 ValidRelocs.emplace_back(Offset64, RelocSize, 0, Mapping);
1913 }
1914 }
1915 }
1916
1917 /// \brief Dispatch the valid relocation finding logic to the
1918 /// appropriate handler depending on the object file format.
findValidRelocs(const object::SectionRef & Section,const object::ObjectFile & Obj,const DebugMapObject & DMO)1919 bool DwarfLinker::RelocationManager::findValidRelocs(
1920 const object::SectionRef &Section, const object::ObjectFile &Obj,
1921 const DebugMapObject &DMO) {
1922 // Dispatch to the right handler depending on the file type.
1923 if (auto *MachOObj = dyn_cast<object::MachOObjectFile>(&Obj))
1924 findValidRelocsMachO(Section, *MachOObj, DMO);
1925 else
1926 Linker.reportWarning(Twine("unsupported object file type: ") +
1927 Obj.getFileName());
1928
1929 if (ValidRelocs.empty())
1930 return false;
1931
1932 // Sort the relocations by offset. We will walk the DIEs linearly in
1933 // the file, this allows us to just keep an index in the relocation
1934 // array that we advance during our walk, rather than resorting to
1935 // some associative container. See DwarfLinker::NextValidReloc.
1936 std::sort(ValidRelocs.begin(), ValidRelocs.end());
1937 return true;
1938 }
1939
1940 /// \brief Look for relocations in the debug_info section that match
1941 /// entries in the debug map. These relocations will drive the Dwarf
1942 /// link by indicating which DIEs refer to symbols present in the
1943 /// linked binary.
1944 /// \returns wether there are any valid relocations in the debug info.
1945 bool DwarfLinker::RelocationManager::
findValidRelocsInDebugInfo(const object::ObjectFile & Obj,const DebugMapObject & DMO)1946 findValidRelocsInDebugInfo(const object::ObjectFile &Obj,
1947 const DebugMapObject &DMO) {
1948 // Find the debug_info section.
1949 for (const object::SectionRef &Section : Obj.sections()) {
1950 StringRef SectionName;
1951 Section.getName(SectionName);
1952 SectionName = SectionName.substr(SectionName.find_first_not_of("._"));
1953 if (SectionName != "debug_info")
1954 continue;
1955 return findValidRelocs(Section, Obj, DMO);
1956 }
1957 return false;
1958 }
1959
1960 /// \brief Checks that there is a relocation against an actual debug
1961 /// map entry between \p StartOffset and \p NextOffset.
1962 ///
1963 /// This function must be called with offsets in strictly ascending
1964 /// order because it never looks back at relocations it already 'went past'.
1965 /// \returns true and sets Info.InDebugMap if it is the case.
1966 bool DwarfLinker::RelocationManager::
hasValidRelocation(uint32_t StartOffset,uint32_t EndOffset,CompileUnit::DIEInfo & Info)1967 hasValidRelocation(uint32_t StartOffset, uint32_t EndOffset,
1968 CompileUnit::DIEInfo &Info) {
1969 assert(NextValidReloc == 0 ||
1970 StartOffset > ValidRelocs[NextValidReloc - 1].Offset);
1971 if (NextValidReloc >= ValidRelocs.size())
1972 return false;
1973
1974 uint64_t RelocOffset = ValidRelocs[NextValidReloc].Offset;
1975
1976 // We might need to skip some relocs that we didn't consider. For
1977 // example the high_pc of a discarded DIE might contain a reloc that
1978 // is in the list because it actually corresponds to the start of a
1979 // function that is in the debug map.
1980 while (RelocOffset < StartOffset && NextValidReloc < ValidRelocs.size() - 1)
1981 RelocOffset = ValidRelocs[++NextValidReloc].Offset;
1982
1983 if (RelocOffset < StartOffset || RelocOffset >= EndOffset)
1984 return false;
1985
1986 const auto &ValidReloc = ValidRelocs[NextValidReloc++];
1987 const auto &Mapping = ValidReloc.Mapping->getValue();
1988 if (Linker.Options.Verbose)
1989 outs() << "Found valid debug map entry: " << ValidReloc.Mapping->getKey()
1990 << " " << format("\t%016" PRIx64 " => %016" PRIx64,
1991 uint64_t(Mapping.ObjectAddress),
1992 uint64_t(Mapping.BinaryAddress));
1993
1994 Info.AddrAdjust = int64_t(Mapping.BinaryAddress) + ValidReloc.Addend -
1995 Mapping.ObjectAddress;
1996 Info.InDebugMap = true;
1997 return true;
1998 }
1999
2000 /// \brief Get the starting and ending (exclusive) offset for the
2001 /// attribute with index \p Idx descibed by \p Abbrev. \p Offset is
2002 /// supposed to point to the position of the first attribute described
2003 /// by \p Abbrev.
2004 /// \return [StartOffset, EndOffset) as a pair.
2005 static std::pair<uint32_t, uint32_t>
getAttributeOffsets(const DWARFAbbreviationDeclaration * Abbrev,unsigned Idx,unsigned Offset,const DWARFUnit & Unit)2006 getAttributeOffsets(const DWARFAbbreviationDeclaration *Abbrev, unsigned Idx,
2007 unsigned Offset, const DWARFUnit &Unit) {
2008 DataExtractor Data = Unit.getDebugInfoExtractor();
2009
2010 for (unsigned i = 0; i < Idx; ++i)
2011 DWARFFormValue::skipValue(Abbrev->getFormByIndex(i), Data, &Offset, &Unit);
2012
2013 uint32_t End = Offset;
2014 DWARFFormValue::skipValue(Abbrev->getFormByIndex(Idx), Data, &End, &Unit);
2015
2016 return std::make_pair(Offset, End);
2017 }
2018
2019 /// \brief Check if a variable describing DIE should be kept.
2020 /// \returns updated TraversalFlags.
shouldKeepVariableDIE(RelocationManager & RelocMgr,const DWARFDebugInfoEntryMinimal & DIE,CompileUnit & Unit,CompileUnit::DIEInfo & MyInfo,unsigned Flags)2021 unsigned DwarfLinker::shouldKeepVariableDIE(RelocationManager &RelocMgr,
2022 const DWARFDebugInfoEntryMinimal &DIE,
2023 CompileUnit &Unit,
2024 CompileUnit::DIEInfo &MyInfo,
2025 unsigned Flags) {
2026 const auto *Abbrev = DIE.getAbbreviationDeclarationPtr();
2027
2028 // Global variables with constant value can always be kept.
2029 if (!(Flags & TF_InFunctionScope) &&
2030 Abbrev->findAttributeIndex(dwarf::DW_AT_const_value) != -1U) {
2031 MyInfo.InDebugMap = true;
2032 return Flags | TF_Keep;
2033 }
2034
2035 uint32_t LocationIdx = Abbrev->findAttributeIndex(dwarf::DW_AT_location);
2036 if (LocationIdx == -1U)
2037 return Flags;
2038
2039 uint32_t Offset = DIE.getOffset() + getULEB128Size(Abbrev->getCode());
2040 const DWARFUnit &OrigUnit = Unit.getOrigUnit();
2041 uint32_t LocationOffset, LocationEndOffset;
2042 std::tie(LocationOffset, LocationEndOffset) =
2043 getAttributeOffsets(Abbrev, LocationIdx, Offset, OrigUnit);
2044
2045 // See if there is a relocation to a valid debug map entry inside
2046 // this variable's location. The order is important here. We want to
2047 // always check in the variable has a valid relocation, so that the
2048 // DIEInfo is filled. However, we don't want a static variable in a
2049 // function to force us to keep the enclosing function.
2050 if (!RelocMgr.hasValidRelocation(LocationOffset, LocationEndOffset, MyInfo) ||
2051 (Flags & TF_InFunctionScope))
2052 return Flags;
2053
2054 if (Options.Verbose)
2055 DIE.dump(outs(), const_cast<DWARFUnit *>(&OrigUnit), 0, 8 /* Indent */);
2056
2057 return Flags | TF_Keep;
2058 }
2059
2060 /// \brief Check if a function describing DIE should be kept.
2061 /// \returns updated TraversalFlags.
shouldKeepSubprogramDIE(RelocationManager & RelocMgr,const DWARFDebugInfoEntryMinimal & DIE,CompileUnit & Unit,CompileUnit::DIEInfo & MyInfo,unsigned Flags)2062 unsigned DwarfLinker::shouldKeepSubprogramDIE(
2063 RelocationManager &RelocMgr,
2064 const DWARFDebugInfoEntryMinimal &DIE, CompileUnit &Unit,
2065 CompileUnit::DIEInfo &MyInfo, unsigned Flags) {
2066 const auto *Abbrev = DIE.getAbbreviationDeclarationPtr();
2067
2068 Flags |= TF_InFunctionScope;
2069
2070 uint32_t LowPcIdx = Abbrev->findAttributeIndex(dwarf::DW_AT_low_pc);
2071 if (LowPcIdx == -1U)
2072 return Flags;
2073
2074 uint32_t Offset = DIE.getOffset() + getULEB128Size(Abbrev->getCode());
2075 const DWARFUnit &OrigUnit = Unit.getOrigUnit();
2076 uint32_t LowPcOffset, LowPcEndOffset;
2077 std::tie(LowPcOffset, LowPcEndOffset) =
2078 getAttributeOffsets(Abbrev, LowPcIdx, Offset, OrigUnit);
2079
2080 uint64_t LowPc =
2081 DIE.getAttributeValueAsAddress(&OrigUnit, dwarf::DW_AT_low_pc, -1ULL);
2082 assert(LowPc != -1ULL && "low_pc attribute is not an address.");
2083 if (LowPc == -1ULL ||
2084 !RelocMgr.hasValidRelocation(LowPcOffset, LowPcEndOffset, MyInfo))
2085 return Flags;
2086
2087 if (Options.Verbose)
2088 DIE.dump(outs(), const_cast<DWARFUnit *>(&OrigUnit), 0, 8 /* Indent */);
2089
2090 Flags |= TF_Keep;
2091
2092 DWARFFormValue HighPcValue;
2093 if (!DIE.getAttributeValue(&OrigUnit, dwarf::DW_AT_high_pc, HighPcValue)) {
2094 reportWarning("Function without high_pc. Range will be discarded.\n",
2095 &OrigUnit, &DIE);
2096 return Flags;
2097 }
2098
2099 uint64_t HighPc;
2100 if (HighPcValue.isFormClass(DWARFFormValue::FC_Address)) {
2101 HighPc = *HighPcValue.getAsAddress(&OrigUnit);
2102 } else {
2103 assert(HighPcValue.isFormClass(DWARFFormValue::FC_Constant));
2104 HighPc = LowPc + *HighPcValue.getAsUnsignedConstant();
2105 }
2106
2107 // Replace the debug map range with a more accurate one.
2108 Ranges[LowPc] = std::make_pair(HighPc, MyInfo.AddrAdjust);
2109 Unit.addFunctionRange(LowPc, HighPc, MyInfo.AddrAdjust);
2110 return Flags;
2111 }
2112
2113 /// \brief Check if a DIE should be kept.
2114 /// \returns updated TraversalFlags.
shouldKeepDIE(RelocationManager & RelocMgr,const DWARFDebugInfoEntryMinimal & DIE,CompileUnit & Unit,CompileUnit::DIEInfo & MyInfo,unsigned Flags)2115 unsigned DwarfLinker::shouldKeepDIE(RelocationManager &RelocMgr,
2116 const DWARFDebugInfoEntryMinimal &DIE,
2117 CompileUnit &Unit,
2118 CompileUnit::DIEInfo &MyInfo,
2119 unsigned Flags) {
2120 switch (DIE.getTag()) {
2121 case dwarf::DW_TAG_constant:
2122 case dwarf::DW_TAG_variable:
2123 return shouldKeepVariableDIE(RelocMgr, DIE, Unit, MyInfo, Flags);
2124 case dwarf::DW_TAG_subprogram:
2125 return shouldKeepSubprogramDIE(RelocMgr, DIE, Unit, MyInfo, Flags);
2126 case dwarf::DW_TAG_module:
2127 case dwarf::DW_TAG_imported_module:
2128 case dwarf::DW_TAG_imported_declaration:
2129 case dwarf::DW_TAG_imported_unit:
2130 // We always want to keep these.
2131 return Flags | TF_Keep;
2132 }
2133
2134 return Flags;
2135 }
2136
2137 /// \brief Mark the passed DIE as well as all the ones it depends on
2138 /// as kept.
2139 ///
2140 /// This function is called by lookForDIEsToKeep on DIEs that are
2141 /// newly discovered to be needed in the link. It recursively calls
2142 /// back to lookForDIEsToKeep while adding TF_DependencyWalk to the
2143 /// TraversalFlags to inform it that it's not doing the primary DIE
2144 /// tree walk.
keepDIEAndDependencies(RelocationManager & RelocMgr,const DWARFDebugInfoEntryMinimal & Die,CompileUnit::DIEInfo & MyInfo,const DebugMapObject & DMO,CompileUnit & CU,bool UseODR)2145 void DwarfLinker::keepDIEAndDependencies(RelocationManager &RelocMgr,
2146 const DWARFDebugInfoEntryMinimal &Die,
2147 CompileUnit::DIEInfo &MyInfo,
2148 const DebugMapObject &DMO,
2149 CompileUnit &CU, bool UseODR) {
2150 const DWARFUnit &Unit = CU.getOrigUnit();
2151 MyInfo.Keep = true;
2152
2153 // First mark all the parent chain as kept.
2154 unsigned AncestorIdx = MyInfo.ParentIdx;
2155 while (!CU.getInfo(AncestorIdx).Keep) {
2156 unsigned ODRFlag = UseODR ? TF_ODR : 0;
2157 lookForDIEsToKeep(RelocMgr, *Unit.getDIEAtIndex(AncestorIdx), DMO, CU,
2158 TF_ParentWalk | TF_Keep | TF_DependencyWalk | ODRFlag);
2159 AncestorIdx = CU.getInfo(AncestorIdx).ParentIdx;
2160 }
2161
2162 // Then we need to mark all the DIEs referenced by this DIE's
2163 // attributes as kept.
2164 DataExtractor Data = Unit.getDebugInfoExtractor();
2165 const auto *Abbrev = Die.getAbbreviationDeclarationPtr();
2166 uint32_t Offset = Die.getOffset() + getULEB128Size(Abbrev->getCode());
2167
2168 // Mark all DIEs referenced through atttributes as kept.
2169 for (const auto &AttrSpec : Abbrev->attributes()) {
2170 DWARFFormValue Val(AttrSpec.Form);
2171
2172 if (!Val.isFormClass(DWARFFormValue::FC_Reference)) {
2173 DWARFFormValue::skipValue(AttrSpec.Form, Data, &Offset, &Unit);
2174 continue;
2175 }
2176
2177 Val.extractValue(Data, &Offset, &Unit);
2178 CompileUnit *ReferencedCU;
2179 if (const auto *RefDIE =
2180 resolveDIEReference(*this, MutableArrayRef<CompileUnit>(Units), Val,
2181 Unit, Die, ReferencedCU)) {
2182 uint32_t RefIdx = ReferencedCU->getOrigUnit().getDIEIndex(RefDIE);
2183 CompileUnit::DIEInfo &Info = ReferencedCU->getInfo(RefIdx);
2184 // If the referenced DIE has a DeclContext that has already been
2185 // emitted, then do not keep the one in this CU. We'll link to
2186 // the canonical DIE in cloneDieReferenceAttribute.
2187 // FIXME: compatibility with dsymutil-classic. UseODR shouldn't
2188 // be necessary and could be advantageously replaced by
2189 // ReferencedCU->hasODR() && CU.hasODR().
2190 // FIXME: compatibility with dsymutil-classic. There is no
2191 // reason not to unique ref_addr references.
2192 if (AttrSpec.Form != dwarf::DW_FORM_ref_addr && UseODR && Info.Ctxt &&
2193 Info.Ctxt != ReferencedCU->getInfo(Info.ParentIdx).Ctxt &&
2194 Info.Ctxt->getCanonicalDIEOffset() && isODRAttribute(AttrSpec.Attr))
2195 continue;
2196
2197 // Keep a module forward declaration if there is no definition.
2198 if (!(isODRAttribute(AttrSpec.Attr) && Info.Ctxt &&
2199 Info.Ctxt->getCanonicalDIEOffset()))
2200 Info.Prune = false;
2201
2202 unsigned ODRFlag = UseODR ? TF_ODR : 0;
2203 lookForDIEsToKeep(RelocMgr, *RefDIE, DMO, *ReferencedCU,
2204 TF_Keep | TF_DependencyWalk | ODRFlag);
2205 }
2206 }
2207 }
2208
2209 /// \brief Recursively walk the \p DIE tree and look for DIEs to
2210 /// keep. Store that information in \p CU's DIEInfo.
2211 ///
2212 /// This function is the entry point of the DIE selection
2213 /// algorithm. It is expected to walk the DIE tree in file order and
2214 /// (though the mediation of its helper) call hasValidRelocation() on
2215 /// each DIE that might be a 'root DIE' (See DwarfLinker class
2216 /// comment).
2217 /// While walking the dependencies of root DIEs, this function is
2218 /// also called, but during these dependency walks the file order is
2219 /// not respected. The TF_DependencyWalk flag tells us which kind of
2220 /// traversal we are currently doing.
lookForDIEsToKeep(RelocationManager & RelocMgr,const DWARFDebugInfoEntryMinimal & Die,const DebugMapObject & DMO,CompileUnit & CU,unsigned Flags)2221 void DwarfLinker::lookForDIEsToKeep(RelocationManager &RelocMgr,
2222 const DWARFDebugInfoEntryMinimal &Die,
2223 const DebugMapObject &DMO, CompileUnit &CU,
2224 unsigned Flags) {
2225 unsigned Idx = CU.getOrigUnit().getDIEIndex(&Die);
2226 CompileUnit::DIEInfo &MyInfo = CU.getInfo(Idx);
2227 bool AlreadyKept = MyInfo.Keep;
2228 if (MyInfo.Prune)
2229 return;
2230
2231 // If the Keep flag is set, we are marking a required DIE's
2232 // dependencies. If our target is already marked as kept, we're all
2233 // set.
2234 if ((Flags & TF_DependencyWalk) && AlreadyKept)
2235 return;
2236
2237 // We must not call shouldKeepDIE while called from keepDIEAndDependencies,
2238 // because it would screw up the relocation finding logic.
2239 if (!(Flags & TF_DependencyWalk))
2240 Flags = shouldKeepDIE(RelocMgr, Die, CU, MyInfo, Flags);
2241
2242 // If it is a newly kept DIE mark it as well as all its dependencies as kept.
2243 if (!AlreadyKept && (Flags & TF_Keep)) {
2244 bool UseOdr = (Flags & TF_DependencyWalk) ? (Flags & TF_ODR) : CU.hasODR();
2245 keepDIEAndDependencies(RelocMgr, Die, MyInfo, DMO, CU, UseOdr);
2246 }
2247 // The TF_ParentWalk flag tells us that we are currently walking up
2248 // the parent chain of a required DIE, and we don't want to mark all
2249 // the children of the parents as kept (consider for example a
2250 // DW_TAG_namespace node in the parent chain). There are however a
2251 // set of DIE types for which we want to ignore that directive and still
2252 // walk their children.
2253 if (dieNeedsChildrenToBeMeaningful(Die.getTag()))
2254 Flags &= ~TF_ParentWalk;
2255
2256 if (!Die.hasChildren() || (Flags & TF_ParentWalk))
2257 return;
2258
2259 for (auto *Child = Die.getFirstChild(); Child && !Child->isNULL();
2260 Child = Child->getSibling())
2261 lookForDIEsToKeep(RelocMgr, *Child, DMO, CU, Flags);
2262 }
2263
2264 /// \brief Assign an abbreviation numer to \p Abbrev.
2265 ///
2266 /// Our DIEs get freed after every DebugMapObject has been processed,
2267 /// thus the FoldingSet we use to unique DIEAbbrevs cannot refer to
2268 /// the instances hold by the DIEs. When we encounter an abbreviation
2269 /// that we don't know, we create a permanent copy of it.
AssignAbbrev(DIEAbbrev & Abbrev)2270 void DwarfLinker::AssignAbbrev(DIEAbbrev &Abbrev) {
2271 // Check the set for priors.
2272 FoldingSetNodeID ID;
2273 Abbrev.Profile(ID);
2274 void *InsertToken;
2275 DIEAbbrev *InSet = AbbreviationsSet.FindNodeOrInsertPos(ID, InsertToken);
2276
2277 // If it's newly added.
2278 if (InSet) {
2279 // Assign existing abbreviation number.
2280 Abbrev.setNumber(InSet->getNumber());
2281 } else {
2282 // Add to abbreviation list.
2283 Abbreviations.push_back(
2284 llvm::make_unique<DIEAbbrev>(Abbrev.getTag(), Abbrev.hasChildren()));
2285 for (const auto &Attr : Abbrev.getData())
2286 Abbreviations.back()->AddAttribute(Attr.getAttribute(), Attr.getForm());
2287 AbbreviationsSet.InsertNode(Abbreviations.back().get(), InsertToken);
2288 // Assign the unique abbreviation number.
2289 Abbrev.setNumber(Abbreviations.size());
2290 Abbreviations.back()->setNumber(Abbreviations.size());
2291 }
2292 }
2293
cloneStringAttribute(DIE & Die,AttributeSpec AttrSpec,const DWARFFormValue & Val,const DWARFUnit & U)2294 unsigned DwarfLinker::DIECloner::cloneStringAttribute(DIE &Die,
2295 AttributeSpec AttrSpec,
2296 const DWARFFormValue &Val,
2297 const DWARFUnit &U) {
2298 // Switch everything to out of line strings.
2299 const char *String = *Val.getAsCString(&U);
2300 unsigned Offset = Linker.StringPool.getStringOffset(String);
2301 Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr), dwarf::DW_FORM_strp,
2302 DIEInteger(Offset));
2303 return 4;
2304 }
2305
cloneDieReferenceAttribute(DIE & Die,const DWARFDebugInfoEntryMinimal & InputDIE,AttributeSpec AttrSpec,unsigned AttrSize,const DWARFFormValue & Val,CompileUnit & Unit)2306 unsigned DwarfLinker::DIECloner::cloneDieReferenceAttribute(
2307 DIE &Die, const DWARFDebugInfoEntryMinimal &InputDIE,
2308 AttributeSpec AttrSpec, unsigned AttrSize, const DWARFFormValue &Val,
2309 CompileUnit &Unit) {
2310 const DWARFUnit &U = Unit.getOrigUnit();
2311 uint32_t Ref = *Val.getAsReference(&U);
2312 DIE *NewRefDie = nullptr;
2313 CompileUnit *RefUnit = nullptr;
2314 DeclContext *Ctxt = nullptr;
2315
2316 const DWARFDebugInfoEntryMinimal *RefDie =
2317 resolveDIEReference(Linker, CompileUnits, Val, U, InputDIE, RefUnit);
2318
2319 // If the referenced DIE is not found, drop the attribute.
2320 if (!RefDie)
2321 return 0;
2322
2323 unsigned Idx = RefUnit->getOrigUnit().getDIEIndex(RefDie);
2324 CompileUnit::DIEInfo &RefInfo = RefUnit->getInfo(Idx);
2325
2326 // If we already have emitted an equivalent DeclContext, just point
2327 // at it.
2328 if (isODRAttribute(AttrSpec.Attr)) {
2329 Ctxt = RefInfo.Ctxt;
2330 if (Ctxt && Ctxt->getCanonicalDIEOffset()) {
2331 DIEInteger Attr(Ctxt->getCanonicalDIEOffset());
2332 Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
2333 dwarf::DW_FORM_ref_addr, Attr);
2334 return getRefAddrSize(U);
2335 }
2336 }
2337
2338 if (!RefInfo.Clone) {
2339 assert(Ref > InputDIE.getOffset());
2340 // We haven't cloned this DIE yet. Just create an empty one and
2341 // store it. It'll get really cloned when we process it.
2342 RefInfo.Clone = DIE::get(DIEAlloc, dwarf::Tag(RefDie->getTag()));
2343 }
2344 NewRefDie = RefInfo.Clone;
2345
2346 if (AttrSpec.Form == dwarf::DW_FORM_ref_addr ||
2347 (Unit.hasODR() && isODRAttribute(AttrSpec.Attr))) {
2348 // We cannot currently rely on a DIEEntry to emit ref_addr
2349 // references, because the implementation calls back to DwarfDebug
2350 // to find the unit offset. (We don't have a DwarfDebug)
2351 // FIXME: we should be able to design DIEEntry reliance on
2352 // DwarfDebug away.
2353 uint64_t Attr;
2354 if (Ref < InputDIE.getOffset()) {
2355 // We must have already cloned that DIE.
2356 uint32_t NewRefOffset =
2357 RefUnit->getStartOffset() + NewRefDie->getOffset();
2358 Attr = NewRefOffset;
2359 Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
2360 dwarf::DW_FORM_ref_addr, DIEInteger(Attr));
2361 } else {
2362 // A forward reference. Note and fixup later.
2363 Attr = 0xBADDEF;
2364 Unit.noteForwardReference(
2365 NewRefDie, RefUnit, Ctxt,
2366 Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
2367 dwarf::DW_FORM_ref_addr, DIEInteger(Attr)));
2368 }
2369 return getRefAddrSize(U);
2370 }
2371
2372 Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
2373 dwarf::Form(AttrSpec.Form), DIEEntry(*NewRefDie));
2374 return AttrSize;
2375 }
2376
cloneBlockAttribute(DIE & Die,AttributeSpec AttrSpec,const DWARFFormValue & Val,unsigned AttrSize)2377 unsigned DwarfLinker::DIECloner::cloneBlockAttribute(DIE &Die,
2378 AttributeSpec AttrSpec,
2379 const DWARFFormValue &Val,
2380 unsigned AttrSize) {
2381 DIEValueList *Attr;
2382 DIEValue Value;
2383 DIELoc *Loc = nullptr;
2384 DIEBlock *Block = nullptr;
2385 // Just copy the block data over.
2386 if (AttrSpec.Form == dwarf::DW_FORM_exprloc) {
2387 Loc = new (DIEAlloc) DIELoc;
2388 Linker.DIELocs.push_back(Loc);
2389 } else {
2390 Block = new (DIEAlloc) DIEBlock;
2391 Linker.DIEBlocks.push_back(Block);
2392 }
2393 Attr = Loc ? static_cast<DIEValueList *>(Loc)
2394 : static_cast<DIEValueList *>(Block);
2395
2396 if (Loc)
2397 Value = DIEValue(dwarf::Attribute(AttrSpec.Attr),
2398 dwarf::Form(AttrSpec.Form), Loc);
2399 else
2400 Value = DIEValue(dwarf::Attribute(AttrSpec.Attr),
2401 dwarf::Form(AttrSpec.Form), Block);
2402 ArrayRef<uint8_t> Bytes = *Val.getAsBlock();
2403 for (auto Byte : Bytes)
2404 Attr->addValue(DIEAlloc, static_cast<dwarf::Attribute>(0),
2405 dwarf::DW_FORM_data1, DIEInteger(Byte));
2406 // FIXME: If DIEBlock and DIELoc just reuses the Size field of
2407 // the DIE class, this if could be replaced by
2408 // Attr->setSize(Bytes.size()).
2409 if (Linker.Streamer) {
2410 auto *AsmPrinter = &Linker.Streamer->getAsmPrinter();
2411 if (Loc)
2412 Loc->ComputeSize(AsmPrinter);
2413 else
2414 Block->ComputeSize(AsmPrinter);
2415 }
2416 Die.addValue(DIEAlloc, Value);
2417 return AttrSize;
2418 }
2419
cloneAddressAttribute(DIE & Die,AttributeSpec AttrSpec,const DWARFFormValue & Val,const CompileUnit & Unit,AttributesInfo & Info)2420 unsigned DwarfLinker::DIECloner::cloneAddressAttribute(
2421 DIE &Die, AttributeSpec AttrSpec, const DWARFFormValue &Val,
2422 const CompileUnit &Unit, AttributesInfo &Info) {
2423 uint64_t Addr = *Val.getAsAddress(&Unit.getOrigUnit());
2424 if (AttrSpec.Attr == dwarf::DW_AT_low_pc) {
2425 if (Die.getTag() == dwarf::DW_TAG_inlined_subroutine ||
2426 Die.getTag() == dwarf::DW_TAG_lexical_block)
2427 // The low_pc of a block or inline subroutine might get
2428 // relocated because it happens to match the low_pc of the
2429 // enclosing subprogram. To prevent issues with that, always use
2430 // the low_pc from the input DIE if relocations have been applied.
2431 Addr = (Info.OrigLowPc != UINT64_MAX ? Info.OrigLowPc : Addr) +
2432 Info.PCOffset;
2433 else if (Die.getTag() == dwarf::DW_TAG_compile_unit) {
2434 Addr = Unit.getLowPc();
2435 if (Addr == UINT64_MAX)
2436 return 0;
2437 }
2438 Info.HasLowPc = true;
2439 } else if (AttrSpec.Attr == dwarf::DW_AT_high_pc) {
2440 if (Die.getTag() == dwarf::DW_TAG_compile_unit) {
2441 if (uint64_t HighPc = Unit.getHighPc())
2442 Addr = HighPc;
2443 else
2444 return 0;
2445 } else
2446 // If we have a high_pc recorded for the input DIE, use
2447 // it. Otherwise (when no relocations where applied) just use the
2448 // one we just decoded.
2449 Addr = (Info.OrigHighPc ? Info.OrigHighPc : Addr) + Info.PCOffset;
2450 }
2451
2452 Die.addValue(DIEAlloc, static_cast<dwarf::Attribute>(AttrSpec.Attr),
2453 static_cast<dwarf::Form>(AttrSpec.Form), DIEInteger(Addr));
2454 return Unit.getOrigUnit().getAddressByteSize();
2455 }
2456
cloneScalarAttribute(DIE & Die,const DWARFDebugInfoEntryMinimal & InputDIE,CompileUnit & Unit,AttributeSpec AttrSpec,const DWARFFormValue & Val,unsigned AttrSize,AttributesInfo & Info)2457 unsigned DwarfLinker::DIECloner::cloneScalarAttribute(
2458 DIE &Die, const DWARFDebugInfoEntryMinimal &InputDIE, CompileUnit &Unit,
2459 AttributeSpec AttrSpec, const DWARFFormValue &Val, unsigned AttrSize,
2460 AttributesInfo &Info) {
2461 uint64_t Value;
2462 if (AttrSpec.Attr == dwarf::DW_AT_high_pc &&
2463 Die.getTag() == dwarf::DW_TAG_compile_unit) {
2464 if (Unit.getLowPc() == -1ULL)
2465 return 0;
2466 // Dwarf >= 4 high_pc is an size, not an address.
2467 Value = Unit.getHighPc() - Unit.getLowPc();
2468 } else if (AttrSpec.Form == dwarf::DW_FORM_sec_offset)
2469 Value = *Val.getAsSectionOffset();
2470 else if (AttrSpec.Form == dwarf::DW_FORM_sdata)
2471 Value = *Val.getAsSignedConstant();
2472 else if (auto OptionalValue = Val.getAsUnsignedConstant())
2473 Value = *OptionalValue;
2474 else {
2475 Linker.reportWarning(
2476 "Unsupported scalar attribute form. Dropping attribute.",
2477 &Unit.getOrigUnit(), &InputDIE);
2478 return 0;
2479 }
2480 PatchLocation Patch =
2481 Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
2482 dwarf::Form(AttrSpec.Form), DIEInteger(Value));
2483 if (AttrSpec.Attr == dwarf::DW_AT_ranges)
2484 Unit.noteRangeAttribute(Die, Patch);
2485
2486 // A more generic way to check for location attributes would be
2487 // nice, but it's very unlikely that any other attribute needs a
2488 // location list.
2489 else if (AttrSpec.Attr == dwarf::DW_AT_location ||
2490 AttrSpec.Attr == dwarf::DW_AT_frame_base)
2491 Unit.noteLocationAttribute(Patch, Info.PCOffset);
2492 else if (AttrSpec.Attr == dwarf::DW_AT_declaration && Value)
2493 Info.IsDeclaration = true;
2494
2495 return AttrSize;
2496 }
2497
2498 /// \brief Clone \p InputDIE's attribute described by \p AttrSpec with
2499 /// value \p Val, and add it to \p Die.
2500 /// \returns the size of the cloned attribute.
cloneAttribute(DIE & Die,const DWARFDebugInfoEntryMinimal & InputDIE,CompileUnit & Unit,const DWARFFormValue & Val,const AttributeSpec AttrSpec,unsigned AttrSize,AttributesInfo & Info)2501 unsigned DwarfLinker::DIECloner::cloneAttribute(
2502 DIE &Die, const DWARFDebugInfoEntryMinimal &InputDIE, CompileUnit &Unit,
2503 const DWARFFormValue &Val, const AttributeSpec AttrSpec, unsigned AttrSize,
2504 AttributesInfo &Info) {
2505 const DWARFUnit &U = Unit.getOrigUnit();
2506
2507 switch (AttrSpec.Form) {
2508 case dwarf::DW_FORM_strp:
2509 case dwarf::DW_FORM_string:
2510 return cloneStringAttribute(Die, AttrSpec, Val, U);
2511 case dwarf::DW_FORM_ref_addr:
2512 case dwarf::DW_FORM_ref1:
2513 case dwarf::DW_FORM_ref2:
2514 case dwarf::DW_FORM_ref4:
2515 case dwarf::DW_FORM_ref8:
2516 return cloneDieReferenceAttribute(Die, InputDIE, AttrSpec, AttrSize, Val,
2517 Unit);
2518 case dwarf::DW_FORM_block:
2519 case dwarf::DW_FORM_block1:
2520 case dwarf::DW_FORM_block2:
2521 case dwarf::DW_FORM_block4:
2522 case dwarf::DW_FORM_exprloc:
2523 return cloneBlockAttribute(Die, AttrSpec, Val, AttrSize);
2524 case dwarf::DW_FORM_addr:
2525 return cloneAddressAttribute(Die, AttrSpec, Val, Unit, Info);
2526 case dwarf::DW_FORM_data1:
2527 case dwarf::DW_FORM_data2:
2528 case dwarf::DW_FORM_data4:
2529 case dwarf::DW_FORM_data8:
2530 case dwarf::DW_FORM_udata:
2531 case dwarf::DW_FORM_sdata:
2532 case dwarf::DW_FORM_sec_offset:
2533 case dwarf::DW_FORM_flag:
2534 case dwarf::DW_FORM_flag_present:
2535 return cloneScalarAttribute(Die, InputDIE, Unit, AttrSpec, Val, AttrSize,
2536 Info);
2537 default:
2538 Linker.reportWarning(
2539 "Unsupported attribute form in cloneAttribute. Dropping.", &U,
2540 &InputDIE);
2541 }
2542
2543 return 0;
2544 }
2545
2546 /// \brief Apply the valid relocations found by findValidRelocs() to
2547 /// the buffer \p Data, taking into account that Data is at \p BaseOffset
2548 /// in the debug_info section.
2549 ///
2550 /// Like for findValidRelocs(), this function must be called with
2551 /// monotonic \p BaseOffset values.
2552 ///
2553 /// \returns wether any reloc has been applied.
2554 bool DwarfLinker::RelocationManager::
applyValidRelocs(MutableArrayRef<char> Data,uint32_t BaseOffset,bool isLittleEndian)2555 applyValidRelocs(MutableArrayRef<char> Data, uint32_t BaseOffset,
2556 bool isLittleEndian) {
2557 assert((NextValidReloc == 0 ||
2558 BaseOffset > ValidRelocs[NextValidReloc - 1].Offset) &&
2559 "BaseOffset should only be increasing.");
2560 if (NextValidReloc >= ValidRelocs.size())
2561 return false;
2562
2563 // Skip relocs that haven't been applied.
2564 while (NextValidReloc < ValidRelocs.size() &&
2565 ValidRelocs[NextValidReloc].Offset < BaseOffset)
2566 ++NextValidReloc;
2567
2568 bool Applied = false;
2569 uint64_t EndOffset = BaseOffset + Data.size();
2570 while (NextValidReloc < ValidRelocs.size() &&
2571 ValidRelocs[NextValidReloc].Offset >= BaseOffset &&
2572 ValidRelocs[NextValidReloc].Offset < EndOffset) {
2573 const auto &ValidReloc = ValidRelocs[NextValidReloc++];
2574 assert(ValidReloc.Offset - BaseOffset < Data.size());
2575 assert(ValidReloc.Offset - BaseOffset + ValidReloc.Size <= Data.size());
2576 char Buf[8];
2577 uint64_t Value = ValidReloc.Mapping->getValue().BinaryAddress;
2578 Value += ValidReloc.Addend;
2579 for (unsigned i = 0; i != ValidReloc.Size; ++i) {
2580 unsigned Index = isLittleEndian ? i : (ValidReloc.Size - i - 1);
2581 Buf[i] = uint8_t(Value >> (Index * 8));
2582 }
2583 assert(ValidReloc.Size <= sizeof(Buf));
2584 memcpy(&Data[ValidReloc.Offset - BaseOffset], Buf, ValidReloc.Size);
2585 Applied = true;
2586 }
2587
2588 return Applied;
2589 }
2590
isTypeTag(uint16_t Tag)2591 static bool isTypeTag(uint16_t Tag) {
2592 switch (Tag) {
2593 case dwarf::DW_TAG_array_type:
2594 case dwarf::DW_TAG_class_type:
2595 case dwarf::DW_TAG_enumeration_type:
2596 case dwarf::DW_TAG_pointer_type:
2597 case dwarf::DW_TAG_reference_type:
2598 case dwarf::DW_TAG_string_type:
2599 case dwarf::DW_TAG_structure_type:
2600 case dwarf::DW_TAG_subroutine_type:
2601 case dwarf::DW_TAG_typedef:
2602 case dwarf::DW_TAG_union_type:
2603 case dwarf::DW_TAG_ptr_to_member_type:
2604 case dwarf::DW_TAG_set_type:
2605 case dwarf::DW_TAG_subrange_type:
2606 case dwarf::DW_TAG_base_type:
2607 case dwarf::DW_TAG_const_type:
2608 case dwarf::DW_TAG_constant:
2609 case dwarf::DW_TAG_file_type:
2610 case dwarf::DW_TAG_namelist:
2611 case dwarf::DW_TAG_packed_type:
2612 case dwarf::DW_TAG_volatile_type:
2613 case dwarf::DW_TAG_restrict_type:
2614 case dwarf::DW_TAG_interface_type:
2615 case dwarf::DW_TAG_unspecified_type:
2616 case dwarf::DW_TAG_shared_type:
2617 return true;
2618 default:
2619 break;
2620 }
2621 return false;
2622 }
2623
2624 static bool
shouldSkipAttribute(DWARFAbbreviationDeclaration::AttributeSpec AttrSpec,uint16_t Tag,bool InDebugMap,bool SkipPC,bool InFunctionScope)2625 shouldSkipAttribute(DWARFAbbreviationDeclaration::AttributeSpec AttrSpec,
2626 uint16_t Tag, bool InDebugMap, bool SkipPC,
2627 bool InFunctionScope) {
2628 switch (AttrSpec.Attr) {
2629 default:
2630 return false;
2631 case dwarf::DW_AT_low_pc:
2632 case dwarf::DW_AT_high_pc:
2633 case dwarf::DW_AT_ranges:
2634 return SkipPC;
2635 case dwarf::DW_AT_location:
2636 case dwarf::DW_AT_frame_base:
2637 // FIXME: for some reason dsymutil-classic keeps the location
2638 // attributes when they are of block type (ie. not location
2639 // lists). This is totally wrong for globals where we will keep a
2640 // wrong address. It is mostly harmless for locals, but there is
2641 // no point in keeping these anyway when the function wasn't linked.
2642 return (SkipPC || (!InFunctionScope && Tag == dwarf::DW_TAG_variable &&
2643 !InDebugMap)) &&
2644 !DWARFFormValue(AttrSpec.Form).isFormClass(DWARFFormValue::FC_Block);
2645 }
2646 }
2647
cloneDIE(const DWARFDebugInfoEntryMinimal & InputDIE,CompileUnit & Unit,int64_t PCOffset,uint32_t OutOffset,unsigned Flags)2648 DIE *DwarfLinker::DIECloner::cloneDIE(
2649 const DWARFDebugInfoEntryMinimal &InputDIE, CompileUnit &Unit,
2650 int64_t PCOffset, uint32_t OutOffset, unsigned Flags) {
2651 DWARFUnit &U = Unit.getOrigUnit();
2652 unsigned Idx = U.getDIEIndex(&InputDIE);
2653 CompileUnit::DIEInfo &Info = Unit.getInfo(Idx);
2654
2655 // Should the DIE appear in the output?
2656 if (!Unit.getInfo(Idx).Keep)
2657 return nullptr;
2658
2659 uint32_t Offset = InputDIE.getOffset();
2660 // The DIE might have been already created by a forward reference
2661 // (see cloneDieReferenceAttribute()).
2662 DIE *Die = Info.Clone;
2663 if (!Die)
2664 Die = Info.Clone = DIE::get(DIEAlloc, dwarf::Tag(InputDIE.getTag()));
2665 assert(Die->getTag() == InputDIE.getTag());
2666 Die->setOffset(OutOffset);
2667 if ((Unit.hasODR() || Unit.isClangModule()) &&
2668 Die->getTag() != dwarf::DW_TAG_namespace && Info.Ctxt &&
2669 Info.Ctxt != Unit.getInfo(Info.ParentIdx).Ctxt &&
2670 !Info.Ctxt->getCanonicalDIEOffset()) {
2671 // We are about to emit a DIE that is the root of its own valid
2672 // DeclContext tree. Make the current offset the canonical offset
2673 // for this context.
2674 Info.Ctxt->setCanonicalDIEOffset(OutOffset + Unit.getStartOffset());
2675 }
2676
2677 // Extract and clone every attribute.
2678 DataExtractor Data = U.getDebugInfoExtractor();
2679 // Point to the next DIE (generally there is always at least a NULL
2680 // entry after the current one). If this is a lone
2681 // DW_TAG_compile_unit without any children, point to the next unit.
2682 uint32_t NextOffset =
2683 (Idx + 1 < U.getNumDIEs())
2684 ? U.getDIEAtIndex(Idx + 1)->getOffset()
2685 : U.getNextUnitOffset();
2686 AttributesInfo AttrInfo;
2687
2688 // We could copy the data only if we need to aply a relocation to
2689 // it. After testing, it seems there is no performance downside to
2690 // doing the copy unconditionally, and it makes the code simpler.
2691 SmallString<40> DIECopy(Data.getData().substr(Offset, NextOffset - Offset));
2692 Data = DataExtractor(DIECopy, Data.isLittleEndian(), Data.getAddressSize());
2693 // Modify the copy with relocated addresses.
2694 if (RelocMgr.applyValidRelocs(DIECopy, Offset, Data.isLittleEndian())) {
2695 // If we applied relocations, we store the value of high_pc that was
2696 // potentially stored in the input DIE. If high_pc is an address
2697 // (Dwarf version == 2), then it might have been relocated to a
2698 // totally unrelated value (because the end address in the object
2699 // file might be start address of another function which got moved
2700 // independantly by the linker). The computation of the actual
2701 // high_pc value is done in cloneAddressAttribute().
2702 AttrInfo.OrigHighPc =
2703 InputDIE.getAttributeValueAsAddress(&U, dwarf::DW_AT_high_pc, 0);
2704 // Also store the low_pc. It might get relocated in an
2705 // inline_subprogram that happens at the beginning of its
2706 // inlining function.
2707 AttrInfo.OrigLowPc =
2708 InputDIE.getAttributeValueAsAddress(&U, dwarf::DW_AT_low_pc, UINT64_MAX);
2709 }
2710
2711 // Reset the Offset to 0 as we will be working on the local copy of
2712 // the data.
2713 Offset = 0;
2714
2715 const auto *Abbrev = InputDIE.getAbbreviationDeclarationPtr();
2716 Offset += getULEB128Size(Abbrev->getCode());
2717
2718 // We are entering a subprogram. Get and propagate the PCOffset.
2719 if (Die->getTag() == dwarf::DW_TAG_subprogram)
2720 PCOffset = Info.AddrAdjust;
2721 AttrInfo.PCOffset = PCOffset;
2722
2723 if (Abbrev->getTag() == dwarf::DW_TAG_subprogram) {
2724 Flags |= TF_InFunctionScope;
2725 if (!Info.InDebugMap)
2726 Flags |= TF_SkipPC;
2727 }
2728
2729 bool Copied = false;
2730 for (const auto &AttrSpec : Abbrev->attributes()) {
2731 if (shouldSkipAttribute(AttrSpec, Die->getTag(), Info.InDebugMap,
2732 Flags & TF_SkipPC, Flags & TF_InFunctionScope)) {
2733 DWARFFormValue::skipValue(AttrSpec.Form, Data, &Offset, &U);
2734 // FIXME: dsymutil-classic keeps the old abbreviation around
2735 // even if it's not used. We can remove this (and the copyAbbrev
2736 // helper) as soon as bit-for-bit compatibility is not a goal anymore.
2737 if (!Copied) {
2738 copyAbbrev(*InputDIE.getAbbreviationDeclarationPtr(), Unit.hasODR());
2739 Copied = true;
2740 }
2741 continue;
2742 }
2743
2744 DWARFFormValue Val(AttrSpec.Form);
2745 uint32_t AttrSize = Offset;
2746 Val.extractValue(Data, &Offset, &U);
2747 AttrSize = Offset - AttrSize;
2748
2749 OutOffset +=
2750 cloneAttribute(*Die, InputDIE, Unit, Val, AttrSpec, AttrSize, AttrInfo);
2751 }
2752
2753 // Look for accelerator entries.
2754 uint16_t Tag = InputDIE.getTag();
2755 // FIXME: This is slightly wrong. An inline_subroutine without a
2756 // low_pc, but with AT_ranges might be interesting to get into the
2757 // accelerator tables too. For now stick with dsymutil's behavior.
2758 if ((Info.InDebugMap || AttrInfo.HasLowPc) &&
2759 Tag != dwarf::DW_TAG_compile_unit &&
2760 getDIENames(InputDIE, Unit.getOrigUnit(), AttrInfo)) {
2761 if (AttrInfo.MangledName && AttrInfo.MangledName != AttrInfo.Name)
2762 Unit.addNameAccelerator(Die, AttrInfo.MangledName,
2763 AttrInfo.MangledNameOffset,
2764 Tag == dwarf::DW_TAG_inlined_subroutine);
2765 if (AttrInfo.Name)
2766 Unit.addNameAccelerator(Die, AttrInfo.Name, AttrInfo.NameOffset,
2767 Tag == dwarf::DW_TAG_inlined_subroutine);
2768 } else if (isTypeTag(Tag) && !AttrInfo.IsDeclaration &&
2769 getDIENames(InputDIE, Unit.getOrigUnit(), AttrInfo)) {
2770 Unit.addTypeAccelerator(Die, AttrInfo.Name, AttrInfo.NameOffset);
2771 }
2772
2773 // Determine whether there are any children that we want to keep.
2774 bool HasChildren = false;
2775 for (auto *Child = InputDIE.getFirstChild(); Child && !Child->isNULL();
2776 Child = Child->getSibling()) {
2777 unsigned Idx = U.getDIEIndex(Child);
2778 if (Unit.getInfo(Idx).Keep) {
2779 HasChildren = true;
2780 break;
2781 }
2782 }
2783
2784 DIEAbbrev NewAbbrev = Die->generateAbbrev();
2785 if (HasChildren)
2786 NewAbbrev.setChildrenFlag(dwarf::DW_CHILDREN_yes);
2787 // Assign a permanent abbrev number
2788 Linker.AssignAbbrev(NewAbbrev);
2789 Die->setAbbrevNumber(NewAbbrev.getNumber());
2790
2791 // Add the size of the abbreviation number to the output offset.
2792 OutOffset += getULEB128Size(Die->getAbbrevNumber());
2793
2794 if (!HasChildren) {
2795 // Update our size.
2796 Die->setSize(OutOffset - Die->getOffset());
2797 return Die;
2798 }
2799
2800 // Recursively clone children.
2801 for (auto *Child = InputDIE.getFirstChild(); Child && !Child->isNULL();
2802 Child = Child->getSibling()) {
2803 if (DIE *Clone = cloneDIE(*Child, Unit, PCOffset, OutOffset, Flags)) {
2804 Die->addChild(Clone);
2805 OutOffset = Clone->getOffset() + Clone->getSize();
2806 }
2807 }
2808
2809 // Account for the end of children marker.
2810 OutOffset += sizeof(int8_t);
2811 // Update our size.
2812 Die->setSize(OutOffset - Die->getOffset());
2813 return Die;
2814 }
2815
2816 /// \brief Patch the input object file relevant debug_ranges entries
2817 /// and emit them in the output file. Update the relevant attributes
2818 /// to point at the new entries.
patchRangesForUnit(const CompileUnit & Unit,DWARFContext & OrigDwarf) const2819 void DwarfLinker::patchRangesForUnit(const CompileUnit &Unit,
2820 DWARFContext &OrigDwarf) const {
2821 DWARFDebugRangeList RangeList;
2822 const auto &FunctionRanges = Unit.getFunctionRanges();
2823 unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
2824 DataExtractor RangeExtractor(OrigDwarf.getRangeSection(),
2825 OrigDwarf.isLittleEndian(), AddressSize);
2826 auto InvalidRange = FunctionRanges.end(), CurrRange = InvalidRange;
2827 DWARFUnit &OrigUnit = Unit.getOrigUnit();
2828 const auto *OrigUnitDie = OrigUnit.getUnitDIE(false);
2829 uint64_t OrigLowPc = OrigUnitDie->getAttributeValueAsAddress(
2830 &OrigUnit, dwarf::DW_AT_low_pc, -1ULL);
2831 // Ranges addresses are based on the unit's low_pc. Compute the
2832 // offset we need to apply to adapt to the new unit's low_pc.
2833 int64_t UnitPcOffset = 0;
2834 if (OrigLowPc != -1ULL)
2835 UnitPcOffset = int64_t(OrigLowPc) - Unit.getLowPc();
2836
2837 for (const auto &RangeAttribute : Unit.getRangesAttributes()) {
2838 uint32_t Offset = RangeAttribute.get();
2839 RangeAttribute.set(Streamer->getRangesSectionSize());
2840 RangeList.extract(RangeExtractor, &Offset);
2841 const auto &Entries = RangeList.getEntries();
2842 if (!Entries.empty()) {
2843 const DWARFDebugRangeList::RangeListEntry &First = Entries.front();
2844
2845 if (CurrRange == InvalidRange ||
2846 First.StartAddress + OrigLowPc < CurrRange.start() ||
2847 First.StartAddress + OrigLowPc >= CurrRange.stop()) {
2848 CurrRange = FunctionRanges.find(First.StartAddress + OrigLowPc);
2849 if (CurrRange == InvalidRange ||
2850 CurrRange.start() > First.StartAddress + OrigLowPc) {
2851 reportWarning("no mapping for range.");
2852 continue;
2853 }
2854 }
2855 }
2856
2857 Streamer->emitRangesEntries(UnitPcOffset, OrigLowPc, CurrRange, Entries,
2858 AddressSize);
2859 }
2860 }
2861
2862 /// \brief Generate the debug_aranges entries for \p Unit and if the
2863 /// unit has a DW_AT_ranges attribute, also emit the debug_ranges
2864 /// contribution for this attribute.
2865 /// FIXME: this could actually be done right in patchRangesForUnit,
2866 /// but for the sake of initial bit-for-bit compatibility with legacy
2867 /// dsymutil, we have to do it in a delayed pass.
generateUnitRanges(CompileUnit & Unit) const2868 void DwarfLinker::generateUnitRanges(CompileUnit &Unit) const {
2869 auto Attr = Unit.getUnitRangesAttribute();
2870 if (Attr)
2871 Attr->set(Streamer->getRangesSectionSize());
2872 Streamer->emitUnitRangesEntries(Unit, static_cast<bool>(Attr));
2873 }
2874
2875 /// \brief Insert the new line info sequence \p Seq into the current
2876 /// set of already linked line info \p Rows.
insertLineSequence(std::vector<DWARFDebugLine::Row> & Seq,std::vector<DWARFDebugLine::Row> & Rows)2877 static void insertLineSequence(std::vector<DWARFDebugLine::Row> &Seq,
2878 std::vector<DWARFDebugLine::Row> &Rows) {
2879 if (Seq.empty())
2880 return;
2881
2882 if (!Rows.empty() && Rows.back().Address < Seq.front().Address) {
2883 Rows.insert(Rows.end(), Seq.begin(), Seq.end());
2884 Seq.clear();
2885 return;
2886 }
2887
2888 auto InsertPoint = std::lower_bound(
2889 Rows.begin(), Rows.end(), Seq.front(),
2890 [](const DWARFDebugLine::Row &LHS, const DWARFDebugLine::Row &RHS) {
2891 return LHS.Address < RHS.Address;
2892 });
2893
2894 // FIXME: this only removes the unneeded end_sequence if the
2895 // sequences have been inserted in order. using a global sort like
2896 // described in patchLineTableForUnit() and delaying the end_sequene
2897 // elimination to emitLineTableForUnit() we can get rid of all of them.
2898 if (InsertPoint != Rows.end() &&
2899 InsertPoint->Address == Seq.front().Address && InsertPoint->EndSequence) {
2900 *InsertPoint = Seq.front();
2901 Rows.insert(InsertPoint + 1, Seq.begin() + 1, Seq.end());
2902 } else {
2903 Rows.insert(InsertPoint, Seq.begin(), Seq.end());
2904 }
2905
2906 Seq.clear();
2907 }
2908
patchStmtList(DIE & Die,DIEInteger Offset)2909 static void patchStmtList(DIE &Die, DIEInteger Offset) {
2910 for (auto &V : Die.values())
2911 if (V.getAttribute() == dwarf::DW_AT_stmt_list) {
2912 V = DIEValue(V.getAttribute(), V.getForm(), Offset);
2913 return;
2914 }
2915
2916 llvm_unreachable("Didn't find DW_AT_stmt_list in cloned DIE!");
2917 }
2918
2919 /// \brief Extract the line table for \p Unit from \p OrigDwarf, and
2920 /// recreate a relocated version of these for the address ranges that
2921 /// are present in the binary.
patchLineTableForUnit(CompileUnit & Unit,DWARFContext & OrigDwarf)2922 void DwarfLinker::patchLineTableForUnit(CompileUnit &Unit,
2923 DWARFContext &OrigDwarf) {
2924 const DWARFDebugInfoEntryMinimal *CUDie = Unit.getOrigUnit().getUnitDIE();
2925 uint64_t StmtList = CUDie->getAttributeValueAsSectionOffset(
2926 &Unit.getOrigUnit(), dwarf::DW_AT_stmt_list, -1ULL);
2927 if (StmtList == -1ULL)
2928 return;
2929
2930 // Update the cloned DW_AT_stmt_list with the correct debug_line offset.
2931 if (auto *OutputDIE = Unit.getOutputUnitDIE())
2932 patchStmtList(*OutputDIE, DIEInteger(Streamer->getLineSectionSize()));
2933
2934 // Parse the original line info for the unit.
2935 DWARFDebugLine::LineTable LineTable;
2936 uint32_t StmtOffset = StmtList;
2937 StringRef LineData = OrigDwarf.getLineSection().Data;
2938 DataExtractor LineExtractor(LineData, OrigDwarf.isLittleEndian(),
2939 Unit.getOrigUnit().getAddressByteSize());
2940 LineTable.parse(LineExtractor, &OrigDwarf.getLineSection().Relocs,
2941 &StmtOffset);
2942
2943 // This vector is the output line table.
2944 std::vector<DWARFDebugLine::Row> NewRows;
2945 NewRows.reserve(LineTable.Rows.size());
2946
2947 // Current sequence of rows being extracted, before being inserted
2948 // in NewRows.
2949 std::vector<DWARFDebugLine::Row> Seq;
2950 const auto &FunctionRanges = Unit.getFunctionRanges();
2951 auto InvalidRange = FunctionRanges.end(), CurrRange = InvalidRange;
2952
2953 // FIXME: This logic is meant to generate exactly the same output as
2954 // Darwin's classic dsynutil. There is a nicer way to implement this
2955 // by simply putting all the relocated line info in NewRows and simply
2956 // sorting NewRows before passing it to emitLineTableForUnit. This
2957 // should be correct as sequences for a function should stay
2958 // together in the sorted output. There are a few corner cases that
2959 // look suspicious though, and that required to implement the logic
2960 // this way. Revisit that once initial validation is finished.
2961
2962 // Iterate over the object file line info and extract the sequences
2963 // that correspond to linked functions.
2964 for (auto &Row : LineTable.Rows) {
2965 // Check wether we stepped out of the range. The range is
2966 // half-open, but consider accept the end address of the range if
2967 // it is marked as end_sequence in the input (because in that
2968 // case, the relocation offset is accurate and that entry won't
2969 // serve as the start of another function).
2970 if (CurrRange == InvalidRange || Row.Address < CurrRange.start() ||
2971 Row.Address > CurrRange.stop() ||
2972 (Row.Address == CurrRange.stop() && !Row.EndSequence)) {
2973 // We just stepped out of a known range. Insert a end_sequence
2974 // corresponding to the end of the range.
2975 uint64_t StopAddress = CurrRange != InvalidRange
2976 ? CurrRange.stop() + CurrRange.value()
2977 : -1ULL;
2978 CurrRange = FunctionRanges.find(Row.Address);
2979 bool CurrRangeValid =
2980 CurrRange != InvalidRange && CurrRange.start() <= Row.Address;
2981 if (!CurrRangeValid) {
2982 CurrRange = InvalidRange;
2983 if (StopAddress != -1ULL) {
2984 // Try harder by looking in the DebugMapObject function
2985 // ranges map. There are corner cases where this finds a
2986 // valid entry. It's unclear if this is right or wrong, but
2987 // for now do as dsymutil.
2988 // FIXME: Understand exactly what cases this addresses and
2989 // potentially remove it along with the Ranges map.
2990 auto Range = Ranges.lower_bound(Row.Address);
2991 if (Range != Ranges.begin() && Range != Ranges.end())
2992 --Range;
2993
2994 if (Range != Ranges.end() && Range->first <= Row.Address &&
2995 Range->second.first >= Row.Address) {
2996 StopAddress = Row.Address + Range->second.second;
2997 }
2998 }
2999 }
3000 if (StopAddress != -1ULL && !Seq.empty()) {
3001 // Insert end sequence row with the computed end address, but
3002 // the same line as the previous one.
3003 auto NextLine = Seq.back();
3004 NextLine.Address = StopAddress;
3005 NextLine.EndSequence = 1;
3006 NextLine.PrologueEnd = 0;
3007 NextLine.BasicBlock = 0;
3008 NextLine.EpilogueBegin = 0;
3009 Seq.push_back(NextLine);
3010 insertLineSequence(Seq, NewRows);
3011 }
3012
3013 if (!CurrRangeValid)
3014 continue;
3015 }
3016
3017 // Ignore empty sequences.
3018 if (Row.EndSequence && Seq.empty())
3019 continue;
3020
3021 // Relocate row address and add it to the current sequence.
3022 Row.Address += CurrRange.value();
3023 Seq.emplace_back(Row);
3024
3025 if (Row.EndSequence)
3026 insertLineSequence(Seq, NewRows);
3027 }
3028
3029 // Finished extracting, now emit the line tables.
3030 uint32_t PrologueEnd = StmtList + 10 + LineTable.Prologue.PrologueLength;
3031 // FIXME: LLVM hardcodes it's prologue values. We just copy the
3032 // prologue over and that works because we act as both producer and
3033 // consumer. It would be nicer to have a real configurable line
3034 // table emitter.
3035 if (LineTable.Prologue.Version != 2 ||
3036 LineTable.Prologue.DefaultIsStmt != DWARF2_LINE_DEFAULT_IS_STMT ||
3037 LineTable.Prologue.OpcodeBase > 13)
3038 reportWarning("line table paramters mismatch. Cannot emit.");
3039 else {
3040 MCDwarfLineTableParams Params;
3041 Params.DWARF2LineOpcodeBase = LineTable.Prologue.OpcodeBase;
3042 Params.DWARF2LineBase = LineTable.Prologue.LineBase;
3043 Params.DWARF2LineRange = LineTable.Prologue.LineRange;
3044 Streamer->emitLineTableForUnit(Params,
3045 LineData.slice(StmtList + 4, PrologueEnd),
3046 LineTable.Prologue.MinInstLength, NewRows,
3047 Unit.getOrigUnit().getAddressByteSize());
3048 }
3049 }
3050
emitAcceleratorEntriesForUnit(CompileUnit & Unit)3051 void DwarfLinker::emitAcceleratorEntriesForUnit(CompileUnit &Unit) {
3052 Streamer->emitPubNamesForUnit(Unit);
3053 Streamer->emitPubTypesForUnit(Unit);
3054 }
3055
3056 /// \brief Read the frame info stored in the object, and emit the
3057 /// patched frame descriptions for the linked binary.
3058 ///
3059 /// This is actually pretty easy as the data of the CIEs and FDEs can
3060 /// be considered as black boxes and moved as is. The only thing to do
3061 /// is to patch the addresses in the headers.
patchFrameInfoForObject(const DebugMapObject & DMO,DWARFContext & OrigDwarf,unsigned AddrSize)3062 void DwarfLinker::patchFrameInfoForObject(const DebugMapObject &DMO,
3063 DWARFContext &OrigDwarf,
3064 unsigned AddrSize) {
3065 StringRef FrameData = OrigDwarf.getDebugFrameSection();
3066 if (FrameData.empty())
3067 return;
3068
3069 DataExtractor Data(FrameData, OrigDwarf.isLittleEndian(), 0);
3070 uint32_t InputOffset = 0;
3071
3072 // Store the data of the CIEs defined in this object, keyed by their
3073 // offsets.
3074 DenseMap<uint32_t, StringRef> LocalCIES;
3075
3076 while (Data.isValidOffset(InputOffset)) {
3077 uint32_t EntryOffset = InputOffset;
3078 uint32_t InitialLength = Data.getU32(&InputOffset);
3079 if (InitialLength == 0xFFFFFFFF)
3080 return reportWarning("Dwarf64 bits no supported");
3081
3082 uint32_t CIEId = Data.getU32(&InputOffset);
3083 if (CIEId == 0xFFFFFFFF) {
3084 // This is a CIE, store it.
3085 StringRef CIEData = FrameData.substr(EntryOffset, InitialLength + 4);
3086 LocalCIES[EntryOffset] = CIEData;
3087 // The -4 is to account for the CIEId we just read.
3088 InputOffset += InitialLength - 4;
3089 continue;
3090 }
3091
3092 uint32_t Loc = Data.getUnsigned(&InputOffset, AddrSize);
3093
3094 // Some compilers seem to emit frame info that doesn't start at
3095 // the function entry point, thus we can't just lookup the address
3096 // in the debug map. Use the linker's range map to see if the FDE
3097 // describes something that we can relocate.
3098 auto Range = Ranges.upper_bound(Loc);
3099 if (Range != Ranges.begin())
3100 --Range;
3101 if (Range == Ranges.end() || Range->first > Loc ||
3102 Range->second.first <= Loc) {
3103 // The +4 is to account for the size of the InitialLength field itself.
3104 InputOffset = EntryOffset + InitialLength + 4;
3105 continue;
3106 }
3107
3108 // This is an FDE, and we have a mapping.
3109 // Have we already emitted a corresponding CIE?
3110 StringRef CIEData = LocalCIES[CIEId];
3111 if (CIEData.empty())
3112 return reportWarning("Inconsistent debug_frame content. Dropping.");
3113
3114 // Look if we already emitted a CIE that corresponds to the
3115 // referenced one (the CIE data is the key of that lookup).
3116 auto IteratorInserted = EmittedCIEs.insert(
3117 std::make_pair(CIEData, Streamer->getFrameSectionSize()));
3118 // If there is no CIE yet for this ID, emit it.
3119 if (IteratorInserted.second ||
3120 // FIXME: dsymutil-classic only caches the last used CIE for
3121 // reuse. Mimic that behavior for now. Just removing that
3122 // second half of the condition and the LastCIEOffset variable
3123 // makes the code DTRT.
3124 LastCIEOffset != IteratorInserted.first->getValue()) {
3125 LastCIEOffset = Streamer->getFrameSectionSize();
3126 IteratorInserted.first->getValue() = LastCIEOffset;
3127 Streamer->emitCIE(CIEData);
3128 }
3129
3130 // Emit the FDE with updated address and CIE pointer.
3131 // (4 + AddrSize) is the size of the CIEId + initial_location
3132 // fields that will get reconstructed by emitFDE().
3133 unsigned FDERemainingBytes = InitialLength - (4 + AddrSize);
3134 Streamer->emitFDE(IteratorInserted.first->getValue(), AddrSize,
3135 Loc + Range->second.second,
3136 FrameData.substr(InputOffset, FDERemainingBytes));
3137 InputOffset += FDERemainingBytes;
3138 }
3139 }
3140
copyAbbrev(const DWARFAbbreviationDeclaration & Abbrev,bool hasODR)3141 void DwarfLinker::DIECloner::copyAbbrev(
3142 const DWARFAbbreviationDeclaration &Abbrev, bool hasODR) {
3143 DIEAbbrev Copy(dwarf::Tag(Abbrev.getTag()),
3144 dwarf::Form(Abbrev.hasChildren()));
3145
3146 for (const auto &Attr : Abbrev.attributes()) {
3147 uint16_t Form = Attr.Form;
3148 if (hasODR && isODRAttribute(Attr.Attr))
3149 Form = dwarf::DW_FORM_ref_addr;
3150 Copy.AddAttribute(dwarf::Attribute(Attr.Attr), dwarf::Form(Form));
3151 }
3152
3153 Linker.AssignAbbrev(Copy);
3154 }
3155
getDwoId(const DWARFDebugInfoEntryMinimal & CUDie,const DWARFUnit & Unit)3156 static uint64_t getDwoId(const DWARFDebugInfoEntryMinimal &CUDie,
3157 const DWARFUnit &Unit) {
3158 uint64_t DwoId =
3159 CUDie.getAttributeValueAsUnsignedConstant(&Unit, dwarf::DW_AT_dwo_id, 0);
3160 if (!DwoId)
3161 DwoId = CUDie.getAttributeValueAsUnsignedConstant(&Unit,
3162 dwarf::DW_AT_GNU_dwo_id, 0);
3163 return DwoId;
3164 }
3165
registerModuleReference(const DWARFDebugInfoEntryMinimal & CUDie,const DWARFUnit & Unit,DebugMap & ModuleMap,unsigned Indent)3166 bool DwarfLinker::registerModuleReference(
3167 const DWARFDebugInfoEntryMinimal &CUDie, const DWARFUnit &Unit,
3168 DebugMap &ModuleMap, unsigned Indent) {
3169 std::string PCMfile =
3170 CUDie.getAttributeValueAsString(&Unit, dwarf::DW_AT_dwo_name, "");
3171 if (PCMfile.empty())
3172 PCMfile =
3173 CUDie.getAttributeValueAsString(&Unit, dwarf::DW_AT_GNU_dwo_name, "");
3174 if (PCMfile.empty())
3175 return false;
3176
3177 // Clang module DWARF skeleton CUs abuse this for the path to the module.
3178 std::string PCMpath =
3179 CUDie.getAttributeValueAsString(&Unit, dwarf::DW_AT_comp_dir, "");
3180 uint64_t DwoId = getDwoId(CUDie, Unit);
3181
3182 std::string Name =
3183 CUDie.getAttributeValueAsString(&Unit, dwarf::DW_AT_name, "");
3184 if (Name.empty()) {
3185 reportWarning("Anonymous module skeleton CU for " + PCMfile);
3186 return true;
3187 }
3188
3189 if (Options.Verbose) {
3190 outs().indent(Indent);
3191 outs() << "Found clang module reference " << PCMfile;
3192 }
3193
3194 auto Cached = ClangModules.find(PCMfile);
3195 if (Cached != ClangModules.end()) {
3196 if (Cached->second != DwoId)
3197 reportWarning(Twine("hash mismatch: this object file was built against a "
3198 "different version of the module ") + PCMfile);
3199 if (Options.Verbose)
3200 outs() << " [cached].\n";
3201 return true;
3202 }
3203 if (Options.Verbose)
3204 outs() << " ...\n";
3205
3206 // Cyclic dependencies are disallowed by Clang, but we still
3207 // shouldn't run into an infinite loop, so mark it as processed now.
3208 ClangModules.insert({PCMfile, DwoId});
3209 loadClangModule(PCMfile, PCMpath, Name, DwoId, ModuleMap, Indent + 2);
3210 return true;
3211 }
3212
3213 ErrorOr<const object::ObjectFile &>
loadObject(BinaryHolder & BinaryHolder,DebugMapObject & Obj,const DebugMap & Map)3214 DwarfLinker::loadObject(BinaryHolder &BinaryHolder, DebugMapObject &Obj,
3215 const DebugMap &Map) {
3216 auto ErrOrObjs =
3217 BinaryHolder.GetObjectFiles(Obj.getObjectFilename(), Obj.getTimestamp());
3218 if (std::error_code EC = ErrOrObjs.getError()) {
3219 reportWarning(Twine(Obj.getObjectFilename()) + ": " + EC.message());
3220 return EC;
3221 }
3222 auto ErrOrObj = BinaryHolder.Get(Map.getTriple());
3223 if (std::error_code EC = ErrOrObj.getError())
3224 reportWarning(Twine(Obj.getObjectFilename()) + ": " + EC.message());
3225 return ErrOrObj;
3226 }
3227
loadClangModule(StringRef Filename,StringRef ModulePath,StringRef ModuleName,uint64_t DwoId,DebugMap & ModuleMap,unsigned Indent)3228 void DwarfLinker::loadClangModule(StringRef Filename, StringRef ModulePath,
3229 StringRef ModuleName, uint64_t DwoId,
3230 DebugMap &ModuleMap, unsigned Indent) {
3231 SmallString<80> Path(Options.PrependPath);
3232 if (sys::path::is_relative(Filename))
3233 sys::path::append(Path, ModulePath, Filename);
3234 else
3235 sys::path::append(Path, Filename);
3236 BinaryHolder ObjHolder(Options.Verbose);
3237 auto &Obj =
3238 ModuleMap.addDebugMapObject(Path, sys::TimeValue::PosixZeroTime());
3239 auto ErrOrObj = loadObject(ObjHolder, Obj, ModuleMap);
3240 if (!ErrOrObj) {
3241 ClangModules.erase(ClangModules.find(Filename));
3242 return;
3243 }
3244
3245 std::unique_ptr<CompileUnit> Unit;
3246
3247 // Setup access to the debug info.
3248 DWARFContextInMemory DwarfContext(*ErrOrObj);
3249 RelocationManager RelocMgr(*this);
3250 for (const auto &CU : DwarfContext.compile_units()) {
3251 auto *CUDie = CU->getUnitDIE(false);
3252 // Recursively get all modules imported by this one.
3253 if (!registerModuleReference(*CUDie, *CU, ModuleMap, Indent)) {
3254 if (Unit) {
3255 errs() << Filename << ": Clang modules are expected to have exactly"
3256 << " 1 compile unit.\n";
3257 exitDsymutil(1);
3258 }
3259 if (getDwoId(*CUDie, *CU) != DwoId)
3260 reportWarning(
3261 Twine("hash mismatch: this object file was built against a "
3262 "different version of the module ") + Filename);
3263
3264 // Add this module.
3265 Unit = llvm::make_unique<CompileUnit>(*CU, UnitID++, !Options.NoODR,
3266 ModuleName);
3267 Unit->setHasInterestingContent();
3268 analyzeContextInfo(CUDie, 0, *Unit, &ODRContexts.getRoot(), StringPool,
3269 ODRContexts);
3270 // Keep everything.
3271 Unit->markEverythingAsKept();
3272 }
3273 }
3274 if (Options.Verbose) {
3275 outs().indent(Indent);
3276 outs() << "cloning .debug_info from " << Filename << "\n";
3277 }
3278
3279 DIECloner(*this, RelocMgr, DIEAlloc, MutableArrayRef<CompileUnit>(*Unit),
3280 Options)
3281 .cloneAllCompileUnits(DwarfContext);
3282 }
3283
cloneAllCompileUnits(DWARFContextInMemory & DwarfContext)3284 void DwarfLinker::DIECloner::cloneAllCompileUnits(
3285 DWARFContextInMemory &DwarfContext) {
3286 if (!Linker.Streamer)
3287 return;
3288
3289 for (auto &CurrentUnit : CompileUnits) {
3290 const auto *InputDIE = CurrentUnit.getOrigUnit().getUnitDIE();
3291 CurrentUnit.setStartOffset(Linker.OutputDebugInfoSize);
3292 DIE *OutputDIE = cloneDIE(*InputDIE, CurrentUnit, 0 /* PC offset */,
3293 11 /* Unit Header size */, 0);
3294 CurrentUnit.setOutputUnitDIE(OutputDIE);
3295 Linker.OutputDebugInfoSize = CurrentUnit.computeNextUnitOffset();
3296 if (Linker.Options.NoOutput)
3297 continue;
3298 // FIXME: for compatibility with the classic dsymutil, we emit
3299 // an empty line table for the unit, even if the unit doesn't
3300 // actually exist in the DIE tree.
3301 Linker.patchLineTableForUnit(CurrentUnit, DwarfContext);
3302 if (!OutputDIE)
3303 continue;
3304 Linker.patchRangesForUnit(CurrentUnit, DwarfContext);
3305 Linker.Streamer->emitLocationsForUnit(CurrentUnit, DwarfContext);
3306 Linker.emitAcceleratorEntriesForUnit(CurrentUnit);
3307 }
3308
3309 if (Linker.Options.NoOutput)
3310 return;
3311
3312 // Emit all the compile unit's debug information.
3313 for (auto &CurrentUnit : CompileUnits) {
3314 Linker.generateUnitRanges(CurrentUnit);
3315 CurrentUnit.fixupForwardReferences();
3316 Linker.Streamer->emitCompileUnitHeader(CurrentUnit);
3317 if (!CurrentUnit.getOutputUnitDIE())
3318 continue;
3319 Linker.Streamer->emitDIE(*CurrentUnit.getOutputUnitDIE());
3320 }
3321 }
3322
link(const DebugMap & Map)3323 bool DwarfLinker::link(const DebugMap &Map) {
3324
3325 if (!createStreamer(Map.getTriple(), OutputFilename))
3326 return false;
3327
3328 // Size of the DIEs (and headers) generated for the linked output.
3329 OutputDebugInfoSize = 0;
3330 // A unique ID that identifies each compile unit.
3331 UnitID = 0;
3332 DebugMap ModuleMap(Map.getTriple(), Map.getBinaryPath());
3333
3334 for (const auto &Obj : Map.objects()) {
3335 CurrentDebugObject = Obj.get();
3336
3337 if (Options.Verbose)
3338 outs() << "DEBUG MAP OBJECT: " << Obj->getObjectFilename() << "\n";
3339 auto ErrOrObj = loadObject(BinHolder, *Obj, Map);
3340 if (!ErrOrObj)
3341 continue;
3342
3343 // Look for relocations that correspond to debug map entries.
3344 RelocationManager RelocMgr(*this);
3345 if (!RelocMgr.findValidRelocsInDebugInfo(*ErrOrObj, *Obj)) {
3346 if (Options.Verbose)
3347 outs() << "No valid relocations found. Skipping.\n";
3348 continue;
3349 }
3350
3351 // Setup access to the debug info.
3352 DWARFContextInMemory DwarfContext(*ErrOrObj);
3353 startDebugObject(DwarfContext, *Obj);
3354
3355 // In a first phase, just read in the debug info and load all clang modules.
3356 for (const auto &CU : DwarfContext.compile_units()) {
3357 auto *CUDie = CU->getUnitDIE(false);
3358 if (Options.Verbose) {
3359 outs() << "Input compilation unit:";
3360 CUDie->dump(outs(), CU.get(), 0);
3361 }
3362
3363 if (!registerModuleReference(*CUDie, *CU, ModuleMap))
3364 Units.emplace_back(*CU, UnitID++, !Options.NoODR, "");
3365 }
3366
3367 // Now build the DIE parent links that we will use during the next phase.
3368 for (auto &CurrentUnit : Units)
3369 analyzeContextInfo(CurrentUnit.getOrigUnit().getUnitDIE(), 0, CurrentUnit,
3370 &ODRContexts.getRoot(), StringPool, ODRContexts);
3371
3372 // Then mark all the DIEs that need to be present in the linked
3373 // output and collect some information about them. Note that this
3374 // loop can not be merged with the previous one becaue cross-cu
3375 // references require the ParentIdx to be setup for every CU in
3376 // the object file before calling this.
3377 for (auto &CurrentUnit : Units)
3378 lookForDIEsToKeep(RelocMgr, *CurrentUnit.getOrigUnit().getUnitDIE(), *Obj,
3379 CurrentUnit, 0);
3380
3381 // The calls to applyValidRelocs inside cloneDIE will walk the
3382 // reloc array again (in the same way findValidRelocsInDebugInfo()
3383 // did). We need to reset the NextValidReloc index to the beginning.
3384 RelocMgr.resetValidRelocs();
3385 if (RelocMgr.hasValidRelocs())
3386 DIECloner(*this, RelocMgr, DIEAlloc, Units, Options)
3387 .cloneAllCompileUnits(DwarfContext);
3388 if (!Options.NoOutput && !Units.empty())
3389 patchFrameInfoForObject(*Obj, DwarfContext,
3390 Units[0].getOrigUnit().getAddressByteSize());
3391
3392 // Clean-up before starting working on the next object.
3393 endDebugObject();
3394 }
3395
3396 // Emit everything that's global.
3397 if (!Options.NoOutput) {
3398 Streamer->emitAbbrevs(Abbreviations);
3399 Streamer->emitStrings(StringPool);
3400 }
3401
3402 return Options.NoOutput ? true : Streamer->finish(Map);
3403 }
3404 }
3405
3406 /// \brief Get the offset of string \p S in the string table. This
3407 /// can insert a new element or return the offset of a preexisitng
3408 /// one.
getStringOffset(StringRef S)3409 uint32_t NonRelocatableStringpool::getStringOffset(StringRef S) {
3410 if (S.empty() && !Strings.empty())
3411 return 0;
3412
3413 std::pair<uint32_t, StringMapEntryBase *> Entry(0, nullptr);
3414 MapTy::iterator It;
3415 bool Inserted;
3416
3417 // A non-empty string can't be at offset 0, so if we have an entry
3418 // with a 0 offset, it must be a previously interned string.
3419 std::tie(It, Inserted) = Strings.insert(std::make_pair(S, Entry));
3420 if (Inserted || It->getValue().first == 0) {
3421 // Set offset and chain at the end of the entries list.
3422 It->getValue().first = CurrentEndOffset;
3423 CurrentEndOffset += S.size() + 1; // +1 for the '\0'.
3424 Last->getValue().second = &*It;
3425 Last = &*It;
3426 }
3427 return It->getValue().first;
3428 }
3429
3430 /// \brief Put \p S into the StringMap so that it gets permanent
3431 /// storage, but do not actually link it in the chain of elements
3432 /// that go into the output section. A latter call to
3433 /// getStringOffset() with the same string will chain it though.
internString(StringRef S)3434 StringRef NonRelocatableStringpool::internString(StringRef S) {
3435 std::pair<uint32_t, StringMapEntryBase *> Entry(0, nullptr);
3436 auto InsertResult = Strings.insert(std::make_pair(S, Entry));
3437 return InsertResult.first->getKey();
3438 }
3439
warn(const Twine & Warning,const Twine & Context)3440 void warn(const Twine &Warning, const Twine &Context) {
3441 errs() << Twine("while processing ") + Context + ":\n";
3442 errs() << Twine("warning: ") + Warning + "\n";
3443 }
3444
error(const Twine & Error,const Twine & Context)3445 bool error(const Twine &Error, const Twine &Context) {
3446 errs() << Twine("while processing ") + Context + ":\n";
3447 errs() << Twine("error: ") + Error + "\n";
3448 return false;
3449 }
3450
linkDwarf(StringRef OutputFilename,const DebugMap & DM,const LinkOptions & Options)3451 bool linkDwarf(StringRef OutputFilename, const DebugMap &DM,
3452 const LinkOptions &Options) {
3453 DwarfLinker Linker(OutputFilename, Options);
3454 return Linker.link(DM);
3455 }
3456 }
3457 }
3458