xref: /freebsd/contrib/llvm-project/llvm/lib/DebugInfo/Symbolize/Symbolize.cpp (revision 1fd87a682ad7442327078e1eeb63edc4258f9815) 
1 //===-- LLVMSymbolize.cpp -------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // Implementation for LLVM symbolization library.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "llvm/DebugInfo/Symbolize/Symbolize.h"
14 
15 #include "SymbolizableObjectFile.h"
16 
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/BinaryFormat/COFF.h"
19 #include "llvm/Config/config.h"
20 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
21 #include "llvm/DebugInfo/PDB/PDB.h"
22 #include "llvm/DebugInfo/PDB/PDBContext.h"
23 #include "llvm/Debuginfod/Debuginfod.h"
24 #include "llvm/Demangle/Demangle.h"
25 #include "llvm/Object/COFF.h"
26 #include "llvm/Object/MachO.h"
27 #include "llvm/Object/MachOUniversal.h"
28 #include "llvm/Support/CRC.h"
29 #include "llvm/Support/Casting.h"
30 #include "llvm/Support/Compression.h"
31 #include "llvm/Support/DataExtractor.h"
32 #include "llvm/Support/Errc.h"
33 #include "llvm/Support/FileSystem.h"
34 #include "llvm/Support/MemoryBuffer.h"
35 #include "llvm/Support/Path.h"
36 #include <algorithm>
37 #include <cassert>
38 #include <cstring>
39 
40 namespace llvm {
41 namespace symbolize {
42 
43 template <typename T>
44 Expected<DILineInfo>
45 LLVMSymbolizer::symbolizeCodeCommon(const T &ModuleSpecifier,
46                                     object::SectionedAddress ModuleOffset) {
47 
48   auto InfoOrErr = getOrCreateModuleInfo(ModuleSpecifier);
49   if (!InfoOrErr)
50     return InfoOrErr.takeError();
51 
52   SymbolizableModule *Info = *InfoOrErr;
53 
54   // A null module means an error has already been reported. Return an empty
55   // result.
56   if (!Info)
57     return DILineInfo();
58 
59   // If the user is giving us relative addresses, add the preferred base of the
60   // object to the offset before we do the query. It's what DIContext expects.
61   if (Opts.RelativeAddresses)
62     ModuleOffset.Address += Info->getModulePreferredBase();
63 
64   DILineInfo LineInfo = Info->symbolizeCode(
65       ModuleOffset, DILineInfoSpecifier(Opts.PathStyle, Opts.PrintFunctions),
66       Opts.UseSymbolTable);
67   if (Opts.Demangle)
68     LineInfo.FunctionName = DemangleName(LineInfo.FunctionName, Info);
69   return LineInfo;
70 }
71 
72 Expected<DILineInfo>
73 LLVMSymbolizer::symbolizeCode(const ObjectFile &Obj,
74                               object::SectionedAddress ModuleOffset) {
75   return symbolizeCodeCommon(Obj, ModuleOffset);
76 }
77 
78 Expected<DILineInfo>
79 LLVMSymbolizer::symbolizeCode(const std::string &ModuleName,
80                               object::SectionedAddress ModuleOffset) {
81   return symbolizeCodeCommon(ModuleName, ModuleOffset);
82 }
83 
84 template <typename T>
85 Expected<DIInliningInfo> LLVMSymbolizer::symbolizeInlinedCodeCommon(
86     const T &ModuleSpecifier, object::SectionedAddress ModuleOffset) {
87   auto InfoOrErr = getOrCreateModuleInfo(ModuleSpecifier);
88   if (!InfoOrErr)
89     return InfoOrErr.takeError();
90 
91   SymbolizableModule *Info = *InfoOrErr;
92 
93   // A null module means an error has already been reported. Return an empty
94   // result.
95   if (!Info)
96     return DIInliningInfo();
97 
98   // If the user is giving us relative addresses, add the preferred base of the
99   // object to the offset before we do the query. It's what DIContext expects.
100   if (Opts.RelativeAddresses)
101     ModuleOffset.Address += Info->getModulePreferredBase();
102 
103   DIInliningInfo InlinedContext = Info->symbolizeInlinedCode(
104       ModuleOffset, DILineInfoSpecifier(Opts.PathStyle, Opts.PrintFunctions),
105       Opts.UseSymbolTable);
106   if (Opts.Demangle) {
107     for (int i = 0, n = InlinedContext.getNumberOfFrames(); i < n; i++) {
108       auto *Frame = InlinedContext.getMutableFrame(i);
109       Frame->FunctionName = DemangleName(Frame->FunctionName, Info);
110     }
111   }
112   return InlinedContext;
113 }
114 
115 Expected<DIInliningInfo>
116 LLVMSymbolizer::symbolizeInlinedCode(const ObjectFile &Obj,
117                                      object::SectionedAddress ModuleOffset) {
118   return symbolizeInlinedCodeCommon(Obj, ModuleOffset);
119 }
120 
121 Expected<DIInliningInfo>
122 LLVMSymbolizer::symbolizeInlinedCode(const std::string &ModuleName,
123                                      object::SectionedAddress ModuleOffset) {
124   return symbolizeInlinedCodeCommon(ModuleName, ModuleOffset);
125 }
126 
127 template <typename T>
128 Expected<DIGlobal>
129 LLVMSymbolizer::symbolizeDataCommon(const T &ModuleSpecifier,
130                                     object::SectionedAddress ModuleOffset) {
131 
132   auto InfoOrErr = getOrCreateModuleInfo(ModuleSpecifier);
133   if (!InfoOrErr)
134     return InfoOrErr.takeError();
135 
136   SymbolizableModule *Info = *InfoOrErr;
137   // A null module means an error has already been reported. Return an empty
138   // result.
139   if (!Info)
140     return DIGlobal();
141 
142   // If the user is giving us relative addresses, add the preferred base of
143   // the object to the offset before we do the query. It's what DIContext
144   // expects.
145   if (Opts.RelativeAddresses)
146     ModuleOffset.Address += Info->getModulePreferredBase();
147 
148   DIGlobal Global = Info->symbolizeData(ModuleOffset);
149   if (Opts.Demangle)
150     Global.Name = DemangleName(Global.Name, Info);
151   return Global;
152 }
153 
154 Expected<DIGlobal>
155 LLVMSymbolizer::symbolizeData(const ObjectFile &Obj,
156                               object::SectionedAddress ModuleOffset) {
157   return symbolizeDataCommon(Obj, ModuleOffset);
158 }
159 
160 Expected<DIGlobal>
161 LLVMSymbolizer::symbolizeData(const std::string &ModuleName,
162                               object::SectionedAddress ModuleOffset) {
163   return symbolizeDataCommon(ModuleName, ModuleOffset);
164 }
165 
166 template <typename T>
167 Expected<std::vector<DILocal>>
168 LLVMSymbolizer::symbolizeFrameCommon(const T &ModuleSpecifier,
169                                      object::SectionedAddress ModuleOffset) {
170   auto InfoOrErr = getOrCreateModuleInfo(ModuleSpecifier);
171   if (!InfoOrErr)
172     return InfoOrErr.takeError();
173 
174   SymbolizableModule *Info = *InfoOrErr;
175   // A null module means an error has already been reported. Return an empty
176   // result.
177   if (!Info)
178     return std::vector<DILocal>();
179 
180   // If the user is giving us relative addresses, add the preferred base of
181   // the object to the offset before we do the query. It's what DIContext
182   // expects.
183   if (Opts.RelativeAddresses)
184     ModuleOffset.Address += Info->getModulePreferredBase();
185 
186   return Info->symbolizeFrame(ModuleOffset);
187 }
188 
189 Expected<std::vector<DILocal>>
190 LLVMSymbolizer::symbolizeFrame(const ObjectFile &Obj,
191                                object::SectionedAddress ModuleOffset) {
192   return symbolizeFrameCommon(Obj, ModuleOffset);
193 }
194 
195 Expected<std::vector<DILocal>>
196 LLVMSymbolizer::symbolizeFrame(const std::string &ModuleName,
197                                object::SectionedAddress ModuleOffset) {
198   return symbolizeFrameCommon(ModuleName, ModuleOffset);
199 }
200 
201 void LLVMSymbolizer::flush() {
202   ObjectForUBPathAndArch.clear();
203   BinaryForPath.clear();
204   ObjectPairForPathArch.clear();
205   Modules.clear();
206 }
207 
208 namespace {
209 
210 // For Path="/path/to/foo" and Basename="foo" assume that debug info is in
211 // /path/to/foo.dSYM/Contents/Resources/DWARF/foo.
212 // For Path="/path/to/bar.dSYM" and Basename="foo" assume that debug info is in
213 // /path/to/bar.dSYM/Contents/Resources/DWARF/foo.
214 std::string getDarwinDWARFResourceForPath(const std::string &Path,
215                                           const std::string &Basename) {
216   SmallString<16> ResourceName = StringRef(Path);
217   if (sys::path::extension(Path) != ".dSYM") {
218     ResourceName += ".dSYM";
219   }
220   sys::path::append(ResourceName, "Contents", "Resources", "DWARF");
221   sys::path::append(ResourceName, Basename);
222   return std::string(ResourceName.str());
223 }
224 
225 bool checkFileCRC(StringRef Path, uint32_t CRCHash) {
226   ErrorOr<std::unique_ptr<MemoryBuffer>> MB =
227       MemoryBuffer::getFileOrSTDIN(Path);
228   if (!MB)
229     return false;
230   return CRCHash == llvm::crc32(arrayRefFromStringRef(MB.get()->getBuffer()));
231 }
232 
233 bool findDebugBinary(const std::string &OrigPath,
234                      const std::string &DebuglinkName, uint32_t CRCHash,
235                      const std::string &FallbackDebugPath,
236                      std::string &Result) {
237   SmallString<16> OrigDir(OrigPath);
238   llvm::sys::path::remove_filename(OrigDir);
239   SmallString<16> DebugPath = OrigDir;
240   // Try relative/path/to/original_binary/debuglink_name
241   llvm::sys::path::append(DebugPath, DebuglinkName);
242   if (checkFileCRC(DebugPath, CRCHash)) {
243     Result = std::string(DebugPath.str());
244     return true;
245   }
246   // Try relative/path/to/original_binary/.debug/debuglink_name
247   DebugPath = OrigDir;
248   llvm::sys::path::append(DebugPath, ".debug", DebuglinkName);
249   if (checkFileCRC(DebugPath, CRCHash)) {
250     Result = std::string(DebugPath.str());
251     return true;
252   }
253   // Make the path absolute so that lookups will go to
254   // "/usr/lib/debug/full/path/to/debug", not
255   // "/usr/lib/debug/to/debug"
256   llvm::sys::fs::make_absolute(OrigDir);
257   if (!FallbackDebugPath.empty()) {
258     // Try <FallbackDebugPath>/absolute/path/to/original_binary/debuglink_name
259     DebugPath = FallbackDebugPath;
260   } else {
261 #if defined(__NetBSD__)
262     // Try /usr/libdata/debug/absolute/path/to/original_binary/debuglink_name
263     DebugPath = "/usr/libdata/debug";
264 #else
265     // Try /usr/lib/debug/absolute/path/to/original_binary/debuglink_name
266     DebugPath = "/usr/lib/debug";
267 #endif
268   }
269   llvm::sys::path::append(DebugPath, llvm::sys::path::relative_path(OrigDir),
270                           DebuglinkName);
271   if (checkFileCRC(DebugPath, CRCHash)) {
272     Result = std::string(DebugPath.str());
273     return true;
274   }
275   return false;
276 }
277 
278 bool getGNUDebuglinkContents(const ObjectFile *Obj, std::string &DebugName,
279                              uint32_t &CRCHash) {
280   if (!Obj)
281     return false;
282   for (const SectionRef &Section : Obj->sections()) {
283     StringRef Name;
284     consumeError(Section.getName().moveInto(Name));
285 
286     Name = Name.substr(Name.find_first_not_of("._"));
287     if (Name == "gnu_debuglink") {
288       Expected<StringRef> ContentsOrErr = Section.getContents();
289       if (!ContentsOrErr) {
290         consumeError(ContentsOrErr.takeError());
291         return false;
292       }
293       DataExtractor DE(*ContentsOrErr, Obj->isLittleEndian(), 0);
294       uint64_t Offset = 0;
295       if (const char *DebugNameStr = DE.getCStr(&Offset)) {
296         // 4-byte align the offset.
297         Offset = (Offset + 3) & ~0x3;
298         if (DE.isValidOffsetForDataOfSize(Offset, 4)) {
299           DebugName = DebugNameStr;
300           CRCHash = DE.getU32(&Offset);
301           return true;
302         }
303       }
304       break;
305     }
306   }
307   return false;
308 }
309 
310 bool darwinDsymMatchesBinary(const MachOObjectFile *DbgObj,
311                              const MachOObjectFile *Obj) {
312   ArrayRef<uint8_t> dbg_uuid = DbgObj->getUuid();
313   ArrayRef<uint8_t> bin_uuid = Obj->getUuid();
314   if (dbg_uuid.empty() || bin_uuid.empty())
315     return false;
316   return !memcmp(dbg_uuid.data(), bin_uuid.data(), dbg_uuid.size());
317 }
318 
319 template <typename ELFT>
320 Optional<ArrayRef<uint8_t>> getBuildID(const ELFFile<ELFT> &Obj) {
321   auto PhdrsOrErr = Obj.program_headers();
322   if (!PhdrsOrErr) {
323     consumeError(PhdrsOrErr.takeError());
324     return {};
325   }
326   for (const auto &P : *PhdrsOrErr) {
327     if (P.p_type != ELF::PT_NOTE)
328       continue;
329     Error Err = Error::success();
330     for (auto N : Obj.notes(P, Err))
331       if (N.getType() == ELF::NT_GNU_BUILD_ID &&
332           N.getName() == ELF::ELF_NOTE_GNU)
333         return N.getDesc();
334     consumeError(std::move(Err));
335   }
336   return {};
337 }
338 
339 Optional<ArrayRef<uint8_t>> getBuildID(const ELFObjectFileBase *Obj) {
340   Optional<ArrayRef<uint8_t>> BuildID;
341   if (auto *O = dyn_cast<ELFObjectFile<ELF32LE>>(Obj))
342     BuildID = getBuildID(O->getELFFile());
343   else if (auto *O = dyn_cast<ELFObjectFile<ELF32BE>>(Obj))
344     BuildID = getBuildID(O->getELFFile());
345   else if (auto *O = dyn_cast<ELFObjectFile<ELF64LE>>(Obj))
346     BuildID = getBuildID(O->getELFFile());
347   else if (auto *O = dyn_cast<ELFObjectFile<ELF64BE>>(Obj))
348     BuildID = getBuildID(O->getELFFile());
349   else
350     llvm_unreachable("unsupported file format");
351   return BuildID;
352 }
353 
354 bool findDebugBinary(const std::vector<std::string> &DebugFileDirectory,
355                      const ArrayRef<uint8_t> BuildID, std::string &Result) {
356   auto getDebugPath = [&](StringRef Directory) {
357     SmallString<128> Path{Directory};
358     sys::path::append(Path, ".build-id",
359                       llvm::toHex(BuildID[0], /*LowerCase=*/true),
360                       llvm::toHex(BuildID.slice(1), /*LowerCase=*/true));
361     Path += ".debug";
362     return Path;
363   };
364   if (DebugFileDirectory.empty()) {
365     SmallString<128> Path = getDebugPath(
366 #if defined(__NetBSD__)
367         // Try /usr/libdata/debug/.build-id/../...
368         "/usr/libdata/debug"
369 #else
370         // Try /usr/lib/debug/.build-id/../...
371         "/usr/lib/debug"
372 #endif
373     );
374     if (llvm::sys::fs::exists(Path)) {
375       Result = std::string(Path.str());
376       return true;
377     }
378   } else {
379     for (const auto &Directory : DebugFileDirectory) {
380       // Try <debug-file-directory>/.build-id/../...
381       SmallString<128> Path = getDebugPath(Directory);
382       if (llvm::sys::fs::exists(Path)) {
383         Result = std::string(Path.str());
384         return true;
385       }
386     }
387   }
388   // Try debuginfod client cache and known servers.
389   Expected<std::string> PathOrErr = getCachedOrDownloadDebuginfo(BuildID);
390   if (!PathOrErr) {
391     consumeError(PathOrErr.takeError());
392     return false;
393   }
394   Result = *PathOrErr;
395   return true;
396 }
397 
398 } // end anonymous namespace
399 
400 ObjectFile *LLVMSymbolizer::lookUpDsymFile(const std::string &ExePath,
401                                            const MachOObjectFile *MachExeObj,
402                                            const std::string &ArchName) {
403   // On Darwin we may find DWARF in separate object file in
404   // resource directory.
405   std::vector<std::string> DsymPaths;
406   StringRef Filename = sys::path::filename(ExePath);
407   DsymPaths.push_back(
408       getDarwinDWARFResourceForPath(ExePath, std::string(Filename)));
409   for (const auto &Path : Opts.DsymHints) {
410     DsymPaths.push_back(
411         getDarwinDWARFResourceForPath(Path, std::string(Filename)));
412   }
413   for (const auto &Path : DsymPaths) {
414     auto DbgObjOrErr = getOrCreateObject(Path, ArchName);
415     if (!DbgObjOrErr) {
416       // Ignore errors, the file might not exist.
417       consumeError(DbgObjOrErr.takeError());
418       continue;
419     }
420     ObjectFile *DbgObj = DbgObjOrErr.get();
421     if (!DbgObj)
422       continue;
423     const MachOObjectFile *MachDbgObj = dyn_cast<const MachOObjectFile>(DbgObj);
424     if (!MachDbgObj)
425       continue;
426     if (darwinDsymMatchesBinary(MachDbgObj, MachExeObj))
427       return DbgObj;
428   }
429   return nullptr;
430 }
431 
432 ObjectFile *LLVMSymbolizer::lookUpDebuglinkObject(const std::string &Path,
433                                                   const ObjectFile *Obj,
434                                                   const std::string &ArchName) {
435   std::string DebuglinkName;
436   uint32_t CRCHash;
437   std::string DebugBinaryPath;
438   if (!getGNUDebuglinkContents(Obj, DebuglinkName, CRCHash))
439     return nullptr;
440   if (!findDebugBinary(Path, DebuglinkName, CRCHash, Opts.FallbackDebugPath,
441                        DebugBinaryPath))
442     return nullptr;
443   auto DbgObjOrErr = getOrCreateObject(DebugBinaryPath, ArchName);
444   if (!DbgObjOrErr) {
445     // Ignore errors, the file might not exist.
446     consumeError(DbgObjOrErr.takeError());
447     return nullptr;
448   }
449   return DbgObjOrErr.get();
450 }
451 
452 ObjectFile *LLVMSymbolizer::lookUpBuildIDObject(const std::string &Path,
453                                                 const ELFObjectFileBase *Obj,
454                                                 const std::string &ArchName) {
455   auto BuildID = getBuildID(Obj);
456   if (!BuildID)
457     return nullptr;
458   if (BuildID->size() < 2)
459     return nullptr;
460   std::string DebugBinaryPath;
461   if (!findDebugBinary(Opts.DebugFileDirectory, *BuildID, DebugBinaryPath))
462     return nullptr;
463   auto DbgObjOrErr = getOrCreateObject(DebugBinaryPath, ArchName);
464   if (!DbgObjOrErr) {
465     consumeError(DbgObjOrErr.takeError());
466     return nullptr;
467   }
468   return DbgObjOrErr.get();
469 }
470 
471 Expected<LLVMSymbolizer::ObjectPair>
472 LLVMSymbolizer::getOrCreateObjectPair(const std::string &Path,
473                                       const std::string &ArchName) {
474   auto I = ObjectPairForPathArch.find(std::make_pair(Path, ArchName));
475   if (I != ObjectPairForPathArch.end())
476     return I->second;
477 
478   auto ObjOrErr = getOrCreateObject(Path, ArchName);
479   if (!ObjOrErr) {
480     ObjectPairForPathArch.emplace(std::make_pair(Path, ArchName),
481                                   ObjectPair(nullptr, nullptr));
482     return ObjOrErr.takeError();
483   }
484 
485   ObjectFile *Obj = ObjOrErr.get();
486   assert(Obj != nullptr);
487   ObjectFile *DbgObj = nullptr;
488 
489   if (auto MachObj = dyn_cast<const MachOObjectFile>(Obj))
490     DbgObj = lookUpDsymFile(Path, MachObj, ArchName);
491   else if (auto ELFObj = dyn_cast<const ELFObjectFileBase>(Obj))
492     DbgObj = lookUpBuildIDObject(Path, ELFObj, ArchName);
493   if (!DbgObj)
494     DbgObj = lookUpDebuglinkObject(Path, Obj, ArchName);
495   if (!DbgObj)
496     DbgObj = Obj;
497   ObjectPair Res = std::make_pair(Obj, DbgObj);
498   ObjectPairForPathArch.emplace(std::make_pair(Path, ArchName), Res);
499   return Res;
500 }
501 
502 Expected<ObjectFile *>
503 LLVMSymbolizer::getOrCreateObject(const std::string &Path,
504                                   const std::string &ArchName) {
505   Binary *Bin;
506   auto Pair = BinaryForPath.emplace(Path, OwningBinary<Binary>());
507   if (!Pair.second) {
508     Bin = Pair.first->second.getBinary();
509   } else {
510     Expected<OwningBinary<Binary>> BinOrErr = createBinary(Path);
511     if (!BinOrErr)
512       return BinOrErr.takeError();
513     Pair.first->second = std::move(BinOrErr.get());
514     Bin = Pair.first->second.getBinary();
515   }
516 
517   if (!Bin)
518     return static_cast<ObjectFile *>(nullptr);
519 
520   if (MachOUniversalBinary *UB = dyn_cast_or_null<MachOUniversalBinary>(Bin)) {
521     auto I = ObjectForUBPathAndArch.find(std::make_pair(Path, ArchName));
522     if (I != ObjectForUBPathAndArch.end())
523       return I->second.get();
524 
525     Expected<std::unique_ptr<ObjectFile>> ObjOrErr =
526         UB->getMachOObjectForArch(ArchName);
527     if (!ObjOrErr) {
528       ObjectForUBPathAndArch.emplace(std::make_pair(Path, ArchName),
529                                      std::unique_ptr<ObjectFile>());
530       return ObjOrErr.takeError();
531     }
532     ObjectFile *Res = ObjOrErr->get();
533     ObjectForUBPathAndArch.emplace(std::make_pair(Path, ArchName),
534                                    std::move(ObjOrErr.get()));
535     return Res;
536   }
537   if (Bin->isObject()) {
538     return cast<ObjectFile>(Bin);
539   }
540   return errorCodeToError(object_error::arch_not_found);
541 }
542 
543 Expected<SymbolizableModule *>
544 LLVMSymbolizer::createModuleInfo(const ObjectFile *Obj,
545                                  std::unique_ptr<DIContext> Context,
546                                  StringRef ModuleName) {
547   auto InfoOrErr = SymbolizableObjectFile::create(Obj, std::move(Context),
548                                                   Opts.UntagAddresses);
549   std::unique_ptr<SymbolizableModule> SymMod;
550   if (InfoOrErr)
551     SymMod = std::move(*InfoOrErr);
552   auto InsertResult = Modules.insert(
553       std::make_pair(std::string(ModuleName), std::move(SymMod)));
554   assert(InsertResult.second);
555   if (!InfoOrErr)
556     return InfoOrErr.takeError();
557   return InsertResult.first->second.get();
558 }
559 
560 Expected<SymbolizableModule *>
561 LLVMSymbolizer::getOrCreateModuleInfo(const std::string &ModuleName) {
562   auto I = Modules.find(ModuleName);
563   if (I != Modules.end())
564     return I->second.get();
565 
566   std::string BinaryName = ModuleName;
567   std::string ArchName = Opts.DefaultArch;
568   size_t ColonPos = ModuleName.find_last_of(':');
569   // Verify that substring after colon form a valid arch name.
570   if (ColonPos != std::string::npos) {
571     std::string ArchStr = ModuleName.substr(ColonPos + 1);
572     if (Triple(ArchStr).getArch() != Triple::UnknownArch) {
573       BinaryName = ModuleName.substr(0, ColonPos);
574       ArchName = ArchStr;
575     }
576   }
577   auto ObjectsOrErr = getOrCreateObjectPair(BinaryName, ArchName);
578   if (!ObjectsOrErr) {
579     // Failed to find valid object file.
580     Modules.emplace(ModuleName, std::unique_ptr<SymbolizableModule>());
581     return ObjectsOrErr.takeError();
582   }
583   ObjectPair Objects = ObjectsOrErr.get();
584 
585   std::unique_ptr<DIContext> Context;
586   // If this is a COFF object containing PDB info, use a PDBContext to
587   // symbolize. Otherwise, use DWARF.
588   if (auto CoffObject = dyn_cast<COFFObjectFile>(Objects.first)) {
589     const codeview::DebugInfo *DebugInfo;
590     StringRef PDBFileName;
591     auto EC = CoffObject->getDebugPDBInfo(DebugInfo, PDBFileName);
592     if (!EC && DebugInfo != nullptr && !PDBFileName.empty()) {
593 #if 0
594       using namespace pdb;
595       std::unique_ptr<IPDBSession> Session;
596 
597       PDB_ReaderType ReaderType =
598           Opts.UseDIA ? PDB_ReaderType::DIA : PDB_ReaderType::Native;
599       if (auto Err = loadDataForEXE(ReaderType, Objects.first->getFileName(),
600                                     Session)) {
601         Modules.emplace(ModuleName, std::unique_ptr<SymbolizableModule>());
602         // Return along the PDB filename to provide more context
603         return createFileError(PDBFileName, std::move(Err));
604       }
605       Context.reset(new PDBContext(*CoffObject, std::move(Session)));
606 #else
607       return make_error<StringError>(
608           "PDB support not compiled in",
609           std::make_error_code(std::errc::not_supported));
610 #endif
611     }
612   }
613   if (!Context)
614     Context = DWARFContext::create(
615         *Objects.second, DWARFContext::ProcessDebugRelocations::Process,
616         nullptr, Opts.DWPName);
617   return createModuleInfo(Objects.first, std::move(Context), ModuleName);
618 }
619 
620 Expected<SymbolizableModule *>
621 LLVMSymbolizer::getOrCreateModuleInfo(const ObjectFile &Obj) {
622   StringRef ObjName = Obj.getFileName();
623   auto I = Modules.find(ObjName);
624   if (I != Modules.end())
625     return I->second.get();
626 
627   std::unique_ptr<DIContext> Context = DWARFContext::create(Obj);
628   // FIXME: handle COFF object with PDB info to use PDBContext
629   return createModuleInfo(&Obj, std::move(Context), ObjName);
630 }
631 
632 namespace {
633 
634 // Undo these various manglings for Win32 extern "C" functions:
635 // cdecl       - _foo
636 // stdcall     - _foo@12
637 // fastcall    - @foo@12
638 // vectorcall  - foo@@12
639 // These are all different linkage names for 'foo'.
640 StringRef demanglePE32ExternCFunc(StringRef SymbolName) {
641   // Remove any '_' or '@' prefix.
642   char Front = SymbolName.empty() ? '\0' : SymbolName[0];
643   if (Front == '_' || Front == '@')
644     SymbolName = SymbolName.drop_front();
645 
646   // Remove any '@[0-9]+' suffix.
647   if (Front != '?') {
648     size_t AtPos = SymbolName.rfind('@');
649     if (AtPos != StringRef::npos &&
650         all_of(drop_begin(SymbolName, AtPos + 1), isDigit))
651       SymbolName = SymbolName.substr(0, AtPos);
652   }
653 
654   // Remove any ending '@' for vectorcall.
655   if (SymbolName.endswith("@"))
656     SymbolName = SymbolName.drop_back();
657 
658   return SymbolName;
659 }
660 
661 } // end anonymous namespace
662 
663 std::string
664 LLVMSymbolizer::DemangleName(const std::string &Name,
665                              const SymbolizableModule *DbiModuleDescriptor) {
666   std::string Result;
667   if (nonMicrosoftDemangle(Name.c_str(), Result))
668     return Result;
669 
670   if (!Name.empty() && Name.front() == '?') {
671     // Only do MSVC C++ demangling on symbols starting with '?'.
672     int status = 0;
673     char *DemangledName = microsoftDemangle(
674         Name.c_str(), nullptr, nullptr, nullptr, &status,
675         MSDemangleFlags(MSDF_NoAccessSpecifier | MSDF_NoCallingConvention |
676                         MSDF_NoMemberType | MSDF_NoReturnType));
677     if (status != 0)
678       return Name;
679     Result = DemangledName;
680     free(DemangledName);
681     return Result;
682   }
683 
684   if (DbiModuleDescriptor && DbiModuleDescriptor->isWin32Module())
685     return std::string(demanglePE32ExternCFunc(Name));
686   return Name;
687 }
688 
689 } // namespace symbolize
690 } // namespace llvm
691