xref: /freebsd/contrib/llvm-project/llvm/lib/DebugInfo/Symbolize/Symbolize.cpp (revision 79ac3c12a714bcd3f2354c52d948aed9575c46d6) 
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/Demangle/Demangle.h"
24 #include "llvm/Object/COFF.h"
25 #include "llvm/Object/MachO.h"
26 #include "llvm/Object/MachOUniversal.h"
27 #include "llvm/Support/CRC.h"
28 #include "llvm/Support/Casting.h"
29 #include "llvm/Support/Compression.h"
30 #include "llvm/Support/DataExtractor.h"
31 #include "llvm/Support/Errc.h"
32 #include "llvm/Support/FileSystem.h"
33 #include "llvm/Support/MemoryBuffer.h"
34 #include "llvm/Support/Path.h"
35 #include <algorithm>
36 #include <cassert>
37 #include <cstring>
38 
39 namespace llvm {
40 namespace symbolize {
41 
42 Expected<DILineInfo>
43 LLVMSymbolizer::symbolizeCodeCommon(SymbolizableModule *Info,
44                                     object::SectionedAddress ModuleOffset) {
45   // A null module means an error has already been reported. Return an empty
46   // result.
47   if (!Info)
48     return DILineInfo();
49 
50   // If the user is giving us relative addresses, add the preferred base of the
51   // object to the offset before we do the query. It's what DIContext expects.
52   if (Opts.RelativeAddresses)
53     ModuleOffset.Address += Info->getModulePreferredBase();
54 
55   DILineInfo LineInfo = Info->symbolizeCode(
56       ModuleOffset, DILineInfoSpecifier(Opts.PathStyle, Opts.PrintFunctions),
57       Opts.UseSymbolTable);
58   if (Opts.Demangle)
59     LineInfo.FunctionName = DemangleName(LineInfo.FunctionName, Info);
60   return LineInfo;
61 }
62 
63 Expected<DILineInfo>
64 LLVMSymbolizer::symbolizeCode(const ObjectFile &Obj,
65                               object::SectionedAddress ModuleOffset) {
66   StringRef ModuleName = Obj.getFileName();
67   auto I = Modules.find(ModuleName);
68   if (I != Modules.end())
69     return symbolizeCodeCommon(I->second.get(), ModuleOffset);
70 
71   std::unique_ptr<DIContext> Context = DWARFContext::create(Obj);
72   Expected<SymbolizableModule *> InfoOrErr =
73                      createModuleInfo(&Obj, std::move(Context), ModuleName);
74   if (!InfoOrErr)
75     return InfoOrErr.takeError();
76   return symbolizeCodeCommon(*InfoOrErr, ModuleOffset);
77 }
78 
79 Expected<DILineInfo>
80 LLVMSymbolizer::symbolizeCode(const std::string &ModuleName,
81                               object::SectionedAddress ModuleOffset) {
82   Expected<SymbolizableModule *> InfoOrErr = getOrCreateModuleInfo(ModuleName);
83   if (!InfoOrErr)
84     return InfoOrErr.takeError();
85   return symbolizeCodeCommon(*InfoOrErr, ModuleOffset);
86 }
87 
88 Expected<DIInliningInfo>
89 LLVMSymbolizer::symbolizeInlinedCode(const std::string &ModuleName,
90                                      object::SectionedAddress ModuleOffset) {
91   SymbolizableModule *Info;
92   if (auto InfoOrErr = getOrCreateModuleInfo(ModuleName))
93     Info = InfoOrErr.get();
94   else
95     return InfoOrErr.takeError();
96 
97   // A null module means an error has already been reported. Return an empty
98   // result.
99   if (!Info)
100     return DIInliningInfo();
101 
102   // If the user is giving us relative addresses, add the preferred base of the
103   // object to the offset before we do the query. It's what DIContext expects.
104   if (Opts.RelativeAddresses)
105     ModuleOffset.Address += Info->getModulePreferredBase();
106 
107   DIInliningInfo InlinedContext = Info->symbolizeInlinedCode(
108       ModuleOffset, DILineInfoSpecifier(Opts.PathStyle, Opts.PrintFunctions),
109       Opts.UseSymbolTable);
110   if (Opts.Demangle) {
111     for (int i = 0, n = InlinedContext.getNumberOfFrames(); i < n; i++) {
112       auto *Frame = InlinedContext.getMutableFrame(i);
113       Frame->FunctionName = DemangleName(Frame->FunctionName, Info);
114     }
115   }
116   return InlinedContext;
117 }
118 
119 Expected<DIGlobal>
120 LLVMSymbolizer::symbolizeData(const std::string &ModuleName,
121                               object::SectionedAddress ModuleOffset) {
122   SymbolizableModule *Info;
123   if (auto InfoOrErr = getOrCreateModuleInfo(ModuleName))
124     Info = InfoOrErr.get();
125   else
126     return InfoOrErr.takeError();
127 
128   // A null module means an error has already been reported. Return an empty
129   // result.
130   if (!Info)
131     return DIGlobal();
132 
133   // If the user is giving us relative addresses, add the preferred base of
134   // the object to the offset before we do the query. It's what DIContext
135   // expects.
136   if (Opts.RelativeAddresses)
137     ModuleOffset.Address += Info->getModulePreferredBase();
138 
139   DIGlobal Global = Info->symbolizeData(ModuleOffset);
140   if (Opts.Demangle)
141     Global.Name = DemangleName(Global.Name, Info);
142   return Global;
143 }
144 
145 Expected<std::vector<DILocal>>
146 LLVMSymbolizer::symbolizeFrame(const std::string &ModuleName,
147                                object::SectionedAddress ModuleOffset) {
148   SymbolizableModule *Info;
149   if (auto InfoOrErr = getOrCreateModuleInfo(ModuleName))
150     Info = InfoOrErr.get();
151   else
152     return InfoOrErr.takeError();
153 
154   // A null module means an error has already been reported. Return an empty
155   // result.
156   if (!Info)
157     return std::vector<DILocal>();
158 
159   // If the user is giving us relative addresses, add the preferred base of
160   // the object to the offset before we do the query. It's what DIContext
161   // expects.
162   if (Opts.RelativeAddresses)
163     ModuleOffset.Address += Info->getModulePreferredBase();
164 
165   return Info->symbolizeFrame(ModuleOffset);
166 }
167 
168 void LLVMSymbolizer::flush() {
169   ObjectForUBPathAndArch.clear();
170   BinaryForPath.clear();
171   ObjectPairForPathArch.clear();
172   Modules.clear();
173 }
174 
175 namespace {
176 
177 // For Path="/path/to/foo" and Basename="foo" assume that debug info is in
178 // /path/to/foo.dSYM/Contents/Resources/DWARF/foo.
179 // For Path="/path/to/bar.dSYM" and Basename="foo" assume that debug info is in
180 // /path/to/bar.dSYM/Contents/Resources/DWARF/foo.
181 std::string getDarwinDWARFResourceForPath(
182     const std::string &Path, const std::string &Basename) {
183   SmallString<16> ResourceName = StringRef(Path);
184   if (sys::path::extension(Path) != ".dSYM") {
185     ResourceName += ".dSYM";
186   }
187   sys::path::append(ResourceName, "Contents", "Resources", "DWARF");
188   sys::path::append(ResourceName, Basename);
189   return std::string(ResourceName.str());
190 }
191 
192 bool checkFileCRC(StringRef Path, uint32_t CRCHash) {
193   ErrorOr<std::unique_ptr<MemoryBuffer>> MB =
194       MemoryBuffer::getFileOrSTDIN(Path);
195   if (!MB)
196     return false;
197   return CRCHash == llvm::crc32(arrayRefFromStringRef(MB.get()->getBuffer()));
198 }
199 
200 bool findDebugBinary(const std::string &OrigPath,
201                      const std::string &DebuglinkName, uint32_t CRCHash,
202                      const std::string &FallbackDebugPath,
203                      std::string &Result) {
204   SmallString<16> OrigDir(OrigPath);
205   llvm::sys::path::remove_filename(OrigDir);
206   SmallString<16> DebugPath = OrigDir;
207   // Try relative/path/to/original_binary/debuglink_name
208   llvm::sys::path::append(DebugPath, DebuglinkName);
209   if (checkFileCRC(DebugPath, CRCHash)) {
210     Result = std::string(DebugPath.str());
211     return true;
212   }
213   // Try relative/path/to/original_binary/.debug/debuglink_name
214   DebugPath = OrigDir;
215   llvm::sys::path::append(DebugPath, ".debug", DebuglinkName);
216   if (checkFileCRC(DebugPath, CRCHash)) {
217     Result = std::string(DebugPath.str());
218     return true;
219   }
220   // Make the path absolute so that lookups will go to
221   // "/usr/lib/debug/full/path/to/debug", not
222   // "/usr/lib/debug/to/debug"
223   llvm::sys::fs::make_absolute(OrigDir);
224   if (!FallbackDebugPath.empty()) {
225     // Try <FallbackDebugPath>/absolute/path/to/original_binary/debuglink_name
226     DebugPath = FallbackDebugPath;
227   } else {
228 #if defined(__NetBSD__)
229     // Try /usr/libdata/debug/absolute/path/to/original_binary/debuglink_name
230     DebugPath = "/usr/libdata/debug";
231 #else
232     // Try /usr/lib/debug/absolute/path/to/original_binary/debuglink_name
233     DebugPath = "/usr/lib/debug";
234 #endif
235   }
236   llvm::sys::path::append(DebugPath, llvm::sys::path::relative_path(OrigDir),
237                           DebuglinkName);
238   if (checkFileCRC(DebugPath, CRCHash)) {
239     Result = std::string(DebugPath.str());
240     return true;
241   }
242   return false;
243 }
244 
245 bool getGNUDebuglinkContents(const ObjectFile *Obj, std::string &DebugName,
246                              uint32_t &CRCHash) {
247   if (!Obj)
248     return false;
249   for (const SectionRef &Section : Obj->sections()) {
250     StringRef Name;
251     if (Expected<StringRef> NameOrErr = Section.getName())
252       Name = *NameOrErr;
253     else
254       consumeError(NameOrErr.takeError());
255 
256     Name = Name.substr(Name.find_first_not_of("._"));
257     if (Name == "gnu_debuglink") {
258       Expected<StringRef> ContentsOrErr = Section.getContents();
259       if (!ContentsOrErr) {
260         consumeError(ContentsOrErr.takeError());
261         return false;
262       }
263       DataExtractor DE(*ContentsOrErr, Obj->isLittleEndian(), 0);
264       uint64_t Offset = 0;
265       if (const char *DebugNameStr = DE.getCStr(&Offset)) {
266         // 4-byte align the offset.
267         Offset = (Offset + 3) & ~0x3;
268         if (DE.isValidOffsetForDataOfSize(Offset, 4)) {
269           DebugName = DebugNameStr;
270           CRCHash = DE.getU32(&Offset);
271           return true;
272         }
273       }
274       break;
275     }
276   }
277   return false;
278 }
279 
280 bool darwinDsymMatchesBinary(const MachOObjectFile *DbgObj,
281                              const MachOObjectFile *Obj) {
282   ArrayRef<uint8_t> dbg_uuid = DbgObj->getUuid();
283   ArrayRef<uint8_t> bin_uuid = Obj->getUuid();
284   if (dbg_uuid.empty() || bin_uuid.empty())
285     return false;
286   return !memcmp(dbg_uuid.data(), bin_uuid.data(), dbg_uuid.size());
287 }
288 
289 template <typename ELFT>
290 Optional<ArrayRef<uint8_t>> getBuildID(const ELFFile<ELFT> &Obj) {
291   auto PhdrsOrErr = Obj.program_headers();
292   if (!PhdrsOrErr) {
293     consumeError(PhdrsOrErr.takeError());
294     return {};
295   }
296   for (const auto &P : *PhdrsOrErr) {
297     if (P.p_type != ELF::PT_NOTE)
298       continue;
299     Error Err = Error::success();
300     for (auto N : Obj.notes(P, Err))
301       if (N.getType() == ELF::NT_GNU_BUILD_ID && N.getName() == ELF::ELF_NOTE_GNU)
302         return N.getDesc();
303     consumeError(std::move(Err));
304   }
305   return {};
306 }
307 
308 Optional<ArrayRef<uint8_t>> getBuildID(const ELFObjectFileBase *Obj) {
309   Optional<ArrayRef<uint8_t>> BuildID;
310   if (auto *O = dyn_cast<ELFObjectFile<ELF32LE>>(Obj))
311     BuildID = getBuildID(O->getELFFile());
312   else if (auto *O = dyn_cast<ELFObjectFile<ELF32BE>>(Obj))
313     BuildID = getBuildID(O->getELFFile());
314   else if (auto *O = dyn_cast<ELFObjectFile<ELF64LE>>(Obj))
315     BuildID = getBuildID(O->getELFFile());
316   else if (auto *O = dyn_cast<ELFObjectFile<ELF64BE>>(Obj))
317     BuildID = getBuildID(O->getELFFile());
318   else
319     llvm_unreachable("unsupported file format");
320   return BuildID;
321 }
322 
323 bool findDebugBinary(const std::vector<std::string> &DebugFileDirectory,
324                      const ArrayRef<uint8_t> BuildID,
325                      std::string &Result) {
326   auto getDebugPath = [&](StringRef Directory) {
327     SmallString<128> Path{Directory};
328     sys::path::append(Path, ".build-id",
329                       llvm::toHex(BuildID[0], /*LowerCase=*/true),
330                       llvm::toHex(BuildID.slice(1), /*LowerCase=*/true));
331     Path += ".debug";
332     return Path;
333   };
334   if (DebugFileDirectory.empty()) {
335     SmallString<128> Path = getDebugPath(
336 #if defined(__NetBSD__)
337       // Try /usr/libdata/debug/.build-id/../...
338       "/usr/libdata/debug"
339 #else
340       // Try /usr/lib/debug/.build-id/../...
341       "/usr/lib/debug"
342 #endif
343     );
344     if (llvm::sys::fs::exists(Path)) {
345       Result = std::string(Path.str());
346       return true;
347     }
348   } else {
349     for (const auto &Directory : DebugFileDirectory) {
350       // Try <debug-file-directory>/.build-id/../...
351       SmallString<128> Path = getDebugPath(Directory);
352       if (llvm::sys::fs::exists(Path)) {
353         Result = std::string(Path.str());
354         return true;
355       }
356     }
357   }
358   return false;
359 }
360 
361 } // end anonymous namespace
362 
363 ObjectFile *LLVMSymbolizer::lookUpDsymFile(const std::string &ExePath,
364     const MachOObjectFile *MachExeObj, const std::string &ArchName) {
365   // On Darwin we may find DWARF in separate object file in
366   // resource directory.
367   std::vector<std::string> DsymPaths;
368   StringRef Filename = sys::path::filename(ExePath);
369   DsymPaths.push_back(
370       getDarwinDWARFResourceForPath(ExePath, std::string(Filename)));
371   for (const auto &Path : Opts.DsymHints) {
372     DsymPaths.push_back(
373         getDarwinDWARFResourceForPath(Path, std::string(Filename)));
374   }
375   for (const auto &Path : DsymPaths) {
376     auto DbgObjOrErr = getOrCreateObject(Path, ArchName);
377     if (!DbgObjOrErr) {
378       // Ignore errors, the file might not exist.
379       consumeError(DbgObjOrErr.takeError());
380       continue;
381     }
382     ObjectFile *DbgObj = DbgObjOrErr.get();
383     if (!DbgObj)
384       continue;
385     const MachOObjectFile *MachDbgObj = dyn_cast<const MachOObjectFile>(DbgObj);
386     if (!MachDbgObj)
387       continue;
388     if (darwinDsymMatchesBinary(MachDbgObj, MachExeObj))
389       return DbgObj;
390   }
391   return nullptr;
392 }
393 
394 ObjectFile *LLVMSymbolizer::lookUpDebuglinkObject(const std::string &Path,
395                                                   const ObjectFile *Obj,
396                                                   const std::string &ArchName) {
397   std::string DebuglinkName;
398   uint32_t CRCHash;
399   std::string DebugBinaryPath;
400   if (!getGNUDebuglinkContents(Obj, DebuglinkName, CRCHash))
401     return nullptr;
402   if (!findDebugBinary(Path, DebuglinkName, CRCHash, Opts.FallbackDebugPath,
403                        DebugBinaryPath))
404     return nullptr;
405   auto DbgObjOrErr = getOrCreateObject(DebugBinaryPath, ArchName);
406   if (!DbgObjOrErr) {
407     // Ignore errors, the file might not exist.
408     consumeError(DbgObjOrErr.takeError());
409     return nullptr;
410   }
411   return DbgObjOrErr.get();
412 }
413 
414 ObjectFile *LLVMSymbolizer::lookUpBuildIDObject(const std::string &Path,
415                                                 const ELFObjectFileBase *Obj,
416                                                 const std::string &ArchName) {
417   auto BuildID = getBuildID(Obj);
418   if (!BuildID)
419     return nullptr;
420   if (BuildID->size() < 2)
421     return nullptr;
422   std::string DebugBinaryPath;
423   if (!findDebugBinary(Opts.DebugFileDirectory, *BuildID, DebugBinaryPath))
424     return nullptr;
425   auto DbgObjOrErr = getOrCreateObject(DebugBinaryPath, ArchName);
426   if (!DbgObjOrErr) {
427     consumeError(DbgObjOrErr.takeError());
428     return nullptr;
429   }
430   return DbgObjOrErr.get();
431 }
432 
433 Expected<LLVMSymbolizer::ObjectPair>
434 LLVMSymbolizer::getOrCreateObjectPair(const std::string &Path,
435                                       const std::string &ArchName) {
436   auto I = ObjectPairForPathArch.find(std::make_pair(Path, ArchName));
437   if (I != ObjectPairForPathArch.end())
438     return I->second;
439 
440   auto ObjOrErr = getOrCreateObject(Path, ArchName);
441   if (!ObjOrErr) {
442     ObjectPairForPathArch.emplace(std::make_pair(Path, ArchName),
443                                   ObjectPair(nullptr, nullptr));
444     return ObjOrErr.takeError();
445   }
446 
447   ObjectFile *Obj = ObjOrErr.get();
448   assert(Obj != nullptr);
449   ObjectFile *DbgObj = nullptr;
450 
451   if (auto MachObj = dyn_cast<const MachOObjectFile>(Obj))
452     DbgObj = lookUpDsymFile(Path, MachObj, ArchName);
453   else if (auto ELFObj = dyn_cast<const ELFObjectFileBase>(Obj))
454     DbgObj = lookUpBuildIDObject(Path, ELFObj, ArchName);
455   if (!DbgObj)
456     DbgObj = lookUpDebuglinkObject(Path, Obj, ArchName);
457   if (!DbgObj)
458     DbgObj = Obj;
459   ObjectPair Res = std::make_pair(Obj, DbgObj);
460   ObjectPairForPathArch.emplace(std::make_pair(Path, ArchName), Res);
461   return Res;
462 }
463 
464 Expected<ObjectFile *>
465 LLVMSymbolizer::getOrCreateObject(const std::string &Path,
466                                   const std::string &ArchName) {
467   Binary *Bin;
468   auto Pair = BinaryForPath.emplace(Path, OwningBinary<Binary>());
469   if (!Pair.second) {
470     Bin = Pair.first->second.getBinary();
471   } else {
472     Expected<OwningBinary<Binary>> BinOrErr = createBinary(Path);
473     if (!BinOrErr)
474       return BinOrErr.takeError();
475     Pair.first->second = std::move(BinOrErr.get());
476     Bin = Pair.first->second.getBinary();
477   }
478 
479   if (!Bin)
480     return static_cast<ObjectFile *>(nullptr);
481 
482   if (MachOUniversalBinary *UB = dyn_cast_or_null<MachOUniversalBinary>(Bin)) {
483     auto I = ObjectForUBPathAndArch.find(std::make_pair(Path, ArchName));
484     if (I != ObjectForUBPathAndArch.end())
485       return I->second.get();
486 
487     Expected<std::unique_ptr<ObjectFile>> ObjOrErr =
488         UB->getMachOObjectForArch(ArchName);
489     if (!ObjOrErr) {
490       ObjectForUBPathAndArch.emplace(std::make_pair(Path, ArchName),
491                                      std::unique_ptr<ObjectFile>());
492       return ObjOrErr.takeError();
493     }
494     ObjectFile *Res = ObjOrErr->get();
495     ObjectForUBPathAndArch.emplace(std::make_pair(Path, ArchName),
496                                    std::move(ObjOrErr.get()));
497     return Res;
498   }
499   if (Bin->isObject()) {
500     return cast<ObjectFile>(Bin);
501   }
502   return errorCodeToError(object_error::arch_not_found);
503 }
504 
505 Expected<SymbolizableModule *>
506 LLVMSymbolizer::createModuleInfo(const ObjectFile *Obj,
507                                  std::unique_ptr<DIContext> Context,
508                                  StringRef ModuleName) {
509   auto InfoOrErr = SymbolizableObjectFile::create(Obj, std::move(Context),
510                                                   Opts.UntagAddresses);
511   std::unique_ptr<SymbolizableModule> SymMod;
512   if (InfoOrErr)
513     SymMod = std::move(*InfoOrErr);
514   auto InsertResult = Modules.insert(
515       std::make_pair(std::string(ModuleName), std::move(SymMod)));
516   assert(InsertResult.second);
517   if (!InfoOrErr)
518     return InfoOrErr.takeError();
519   return InsertResult.first->second.get();
520 }
521 
522 Expected<SymbolizableModule *>
523 LLVMSymbolizer::getOrCreateModuleInfo(const std::string &ModuleName) {
524   auto I = Modules.find(ModuleName);
525   if (I != Modules.end())
526     return I->second.get();
527 
528   std::string BinaryName = ModuleName;
529   std::string ArchName = Opts.DefaultArch;
530   size_t ColonPos = ModuleName.find_last_of(':');
531   // Verify that substring after colon form a valid arch name.
532   if (ColonPos != std::string::npos) {
533     std::string ArchStr = ModuleName.substr(ColonPos + 1);
534     if (Triple(ArchStr).getArch() != Triple::UnknownArch) {
535       BinaryName = ModuleName.substr(0, ColonPos);
536       ArchName = ArchStr;
537     }
538   }
539   auto ObjectsOrErr = getOrCreateObjectPair(BinaryName, ArchName);
540   if (!ObjectsOrErr) {
541     // Failed to find valid object file.
542     Modules.emplace(ModuleName, std::unique_ptr<SymbolizableModule>());
543     return ObjectsOrErr.takeError();
544   }
545   ObjectPair Objects = ObjectsOrErr.get();
546 
547   std::unique_ptr<DIContext> Context;
548   // If this is a COFF object containing PDB info, use a PDBContext to
549   // symbolize. Otherwise, use DWARF.
550   if (auto CoffObject = dyn_cast<COFFObjectFile>(Objects.first)) {
551     const codeview::DebugInfo *DebugInfo;
552     StringRef PDBFileName;
553     auto EC = CoffObject->getDebugPDBInfo(DebugInfo, PDBFileName);
554     if (!EC && DebugInfo != nullptr && !PDBFileName.empty()) {
555 #if 0
556       using namespace pdb;
557       std::unique_ptr<IPDBSession> Session;
558 
559       PDB_ReaderType ReaderType =
560           Opts.UseDIA ? PDB_ReaderType::DIA : PDB_ReaderType::Native;
561       if (auto Err = loadDataForEXE(ReaderType, Objects.first->getFileName(),
562                                     Session)) {
563         Modules.emplace(ModuleName, std::unique_ptr<SymbolizableModule>());
564         // Return along the PDB filename to provide more context
565         return createFileError(PDBFileName, std::move(Err));
566       }
567       Context.reset(new PDBContext(*CoffObject, std::move(Session)));
568 #else
569       return make_error<StringError>(
570           "PDB support not compiled in",
571           std::make_error_code(std::errc::not_supported));
572 #endif
573     }
574   }
575   if (!Context)
576     Context = DWARFContext::create(*Objects.second, nullptr, Opts.DWPName);
577   return createModuleInfo(Objects.first, std::move(Context), ModuleName);
578 }
579 
580 namespace {
581 
582 // Undo these various manglings for Win32 extern "C" functions:
583 // cdecl       - _foo
584 // stdcall     - _foo@12
585 // fastcall    - @foo@12
586 // vectorcall  - foo@@12
587 // These are all different linkage names for 'foo'.
588 StringRef demanglePE32ExternCFunc(StringRef SymbolName) {
589   // Remove any '_' or '@' prefix.
590   char Front = SymbolName.empty() ? '\0' : SymbolName[0];
591   if (Front == '_' || Front == '@')
592     SymbolName = SymbolName.drop_front();
593 
594   // Remove any '@[0-9]+' suffix.
595   if (Front != '?') {
596     size_t AtPos = SymbolName.rfind('@');
597     if (AtPos != StringRef::npos &&
598         all_of(drop_begin(SymbolName, AtPos + 1), isDigit))
599       SymbolName = SymbolName.substr(0, AtPos);
600   }
601 
602   // Remove any ending '@' for vectorcall.
603   if (SymbolName.endswith("@"))
604     SymbolName = SymbolName.drop_back();
605 
606   return SymbolName;
607 }
608 
609 } // end anonymous namespace
610 
611 std::string
612 LLVMSymbolizer::DemangleName(const std::string &Name,
613                              const SymbolizableModule *DbiModuleDescriptor) {
614   // We can spoil names of symbols with C linkage, so use an heuristic
615   // approach to check if the name should be demangled.
616   if (Name.substr(0, 2) == "_Z") {
617     int status = 0;
618     char *DemangledName = itaniumDemangle(Name.c_str(), nullptr, nullptr, &status);
619     if (status != 0)
620       return Name;
621     std::string Result = DemangledName;
622     free(DemangledName);
623     return Result;
624   }
625 
626   if (!Name.empty() && Name.front() == '?') {
627     // Only do MSVC C++ demangling on symbols starting with '?'.
628     int status = 0;
629     char *DemangledName = microsoftDemangle(
630         Name.c_str(), nullptr, nullptr, nullptr, &status,
631         MSDemangleFlags(MSDF_NoAccessSpecifier | MSDF_NoCallingConvention |
632                         MSDF_NoMemberType | MSDF_NoReturnType));
633     if (status != 0)
634       return Name;
635     std::string Result = DemangledName;
636     free(DemangledName);
637     return Result;
638   }
639 
640   if (DbiModuleDescriptor && DbiModuleDescriptor->isWin32Module())
641     return std::string(demanglePE32ExternCFunc(Name));
642   return Name;
643 }
644 
645 } // namespace symbolize
646 } // namespace llvm
647