xref: /freebsd/contrib/llvm-project/llvm/lib/DebugInfo/Symbolize/Symbolize.cpp (revision 62cfcf62f627e5093fb37026a6d8c98e4d2ef04c) 
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/DebugInfo/DWARF/DWARFContext.h"
20 #include "llvm/DebugInfo/PDB/PDB.h"
21 #include "llvm/DebugInfo/PDB/PDBContext.h"
22 #include "llvm/Demangle/Demangle.h"
23 #include "llvm/Object/COFF.h"
24 #include "llvm/Object/MachO.h"
25 #include "llvm/Object/MachOUniversal.h"
26 #include "llvm/Support/CRC.h"
27 #include "llvm/Support/Casting.h"
28 #include "llvm/Support/Compression.h"
29 #include "llvm/Support/DataExtractor.h"
30 #include "llvm/Support/Errc.h"
31 #include "llvm/Support/FileSystem.h"
32 #include "llvm/Support/MemoryBuffer.h"
33 #include "llvm/Support/Path.h"
34 #include <algorithm>
35 #include <cassert>
36 #include <cstring>
37 
38 namespace llvm {
39 namespace symbolize {
40 
41 Expected<DILineInfo>
42 LLVMSymbolizer::symbolizeCodeCommon(SymbolizableModule *Info,
43                                     object::SectionedAddress ModuleOffset) {
44   // A null module means an error has already been reported. Return an empty
45   // result.
46   if (!Info)
47     return DILineInfo();
48 
49   // If the user is giving us relative addresses, add the preferred base of the
50   // object to the offset before we do the query. It's what DIContext expects.
51   if (Opts.RelativeAddresses)
52     ModuleOffset.Address += Info->getModulePreferredBase();
53 
54   DILineInfo LineInfo = Info->symbolizeCode(ModuleOffset, Opts.PrintFunctions,
55                                             Opts.UseSymbolTable);
56   if (Opts.Demangle)
57     LineInfo.FunctionName = DemangleName(LineInfo.FunctionName, Info);
58   return LineInfo;
59 }
60 
61 Expected<DILineInfo>
62 LLVMSymbolizer::symbolizeCode(const ObjectFile &Obj,
63                               object::SectionedAddress ModuleOffset) {
64   StringRef ModuleName = Obj.getFileName();
65   auto I = Modules.find(ModuleName);
66   if (I != Modules.end())
67     return symbolizeCodeCommon(I->second.get(), ModuleOffset);
68 
69   std::unique_ptr<DIContext> Context =
70         DWARFContext::create(Obj, nullptr, DWARFContext::defaultErrorHandler);
71   Expected<SymbolizableModule *> InfoOrErr =
72                      createModuleInfo(&Obj, std::move(Context), ModuleName);
73   if (!InfoOrErr)
74     return InfoOrErr.takeError();
75   return symbolizeCodeCommon(*InfoOrErr, ModuleOffset);
76 }
77 
78 Expected<DILineInfo>
79 LLVMSymbolizer::symbolizeCode(const std::string &ModuleName,
80                               object::SectionedAddress ModuleOffset) {
81   Expected<SymbolizableModule *> InfoOrErr = getOrCreateModuleInfo(ModuleName);
82   if (!InfoOrErr)
83     return InfoOrErr.takeError();
84   return symbolizeCodeCommon(*InfoOrErr, ModuleOffset);
85 }
86 
87 Expected<DIInliningInfo>
88 LLVMSymbolizer::symbolizeInlinedCode(const std::string &ModuleName,
89                                      object::SectionedAddress ModuleOffset) {
90   SymbolizableModule *Info;
91   if (auto InfoOrErr = getOrCreateModuleInfo(ModuleName))
92     Info = InfoOrErr.get();
93   else
94     return InfoOrErr.takeError();
95 
96   // A null module means an error has already been reported. Return an empty
97   // result.
98   if (!Info)
99     return DIInliningInfo();
100 
101   // If the user is giving us relative addresses, add the preferred base of the
102   // object to the offset before we do the query. It's what DIContext expects.
103   if (Opts.RelativeAddresses)
104     ModuleOffset.Address += Info->getModulePreferredBase();
105 
106   DIInliningInfo InlinedContext = Info->symbolizeInlinedCode(
107       ModuleOffset, Opts.PrintFunctions, Opts.UseSymbolTable);
108   if (Opts.Demangle) {
109     for (int i = 0, n = InlinedContext.getNumberOfFrames(); i < n; i++) {
110       auto *Frame = InlinedContext.getMutableFrame(i);
111       Frame->FunctionName = DemangleName(Frame->FunctionName, Info);
112     }
113   }
114   return InlinedContext;
115 }
116 
117 Expected<DIGlobal>
118 LLVMSymbolizer::symbolizeData(const std::string &ModuleName,
119                               object::SectionedAddress ModuleOffset) {
120   SymbolizableModule *Info;
121   if (auto InfoOrErr = getOrCreateModuleInfo(ModuleName))
122     Info = InfoOrErr.get();
123   else
124     return InfoOrErr.takeError();
125 
126   // A null module means an error has already been reported. Return an empty
127   // result.
128   if (!Info)
129     return DIGlobal();
130 
131   // If the user is giving us relative addresses, add the preferred base of
132   // the object to the offset before we do the query. It's what DIContext
133   // expects.
134   if (Opts.RelativeAddresses)
135     ModuleOffset.Address += Info->getModulePreferredBase();
136 
137   DIGlobal Global = Info->symbolizeData(ModuleOffset);
138   if (Opts.Demangle)
139     Global.Name = DemangleName(Global.Name, Info);
140   return Global;
141 }
142 
143 Expected<std::vector<DILocal>>
144 LLVMSymbolizer::symbolizeFrame(const std::string &ModuleName,
145                                object::SectionedAddress ModuleOffset) {
146   SymbolizableModule *Info;
147   if (auto InfoOrErr = getOrCreateModuleInfo(ModuleName))
148     Info = InfoOrErr.get();
149   else
150     return InfoOrErr.takeError();
151 
152   // A null module means an error has already been reported. Return an empty
153   // result.
154   if (!Info)
155     return std::vector<DILocal>();
156 
157   // If the user is giving us relative addresses, add the preferred base of
158   // the object to the offset before we do the query. It's what DIContext
159   // expects.
160   if (Opts.RelativeAddresses)
161     ModuleOffset.Address += Info->getModulePreferredBase();
162 
163   return Info->symbolizeFrame(ModuleOffset);
164 }
165 
166 void LLVMSymbolizer::flush() {
167   ObjectForUBPathAndArch.clear();
168   BinaryForPath.clear();
169   ObjectPairForPathArch.clear();
170   Modules.clear();
171 }
172 
173 namespace {
174 
175 // For Path="/path/to/foo" and Basename="foo" assume that debug info is in
176 // /path/to/foo.dSYM/Contents/Resources/DWARF/foo.
177 // For Path="/path/to/bar.dSYM" and Basename="foo" assume that debug info is in
178 // /path/to/bar.dSYM/Contents/Resources/DWARF/foo.
179 std::string getDarwinDWARFResourceForPath(
180     const std::string &Path, const std::string &Basename) {
181   SmallString<16> ResourceName = StringRef(Path);
182   if (sys::path::extension(Path) != ".dSYM") {
183     ResourceName += ".dSYM";
184   }
185   sys::path::append(ResourceName, "Contents", "Resources", "DWARF");
186   sys::path::append(ResourceName, Basename);
187   return ResourceName.str();
188 }
189 
190 bool checkFileCRC(StringRef Path, uint32_t CRCHash) {
191   ErrorOr<std::unique_ptr<MemoryBuffer>> MB =
192       MemoryBuffer::getFileOrSTDIN(Path);
193   if (!MB)
194     return false;
195   return CRCHash == llvm::crc32(arrayRefFromStringRef(MB.get()->getBuffer()));
196 }
197 
198 bool findDebugBinary(const std::string &OrigPath,
199                      const std::string &DebuglinkName, uint32_t CRCHash,
200                      const std::string &FallbackDebugPath,
201                      std::string &Result) {
202   SmallString<16> OrigDir(OrigPath);
203   llvm::sys::path::remove_filename(OrigDir);
204   SmallString<16> DebugPath = OrigDir;
205   // Try relative/path/to/original_binary/debuglink_name
206   llvm::sys::path::append(DebugPath, DebuglinkName);
207   if (checkFileCRC(DebugPath, CRCHash)) {
208     Result = DebugPath.str();
209     return true;
210   }
211   // Try relative/path/to/original_binary/.debug/debuglink_name
212   DebugPath = OrigDir;
213   llvm::sys::path::append(DebugPath, ".debug", DebuglinkName);
214   if (checkFileCRC(DebugPath, CRCHash)) {
215     Result = DebugPath.str();
216     return true;
217   }
218   // Make the path absolute so that lookups will go to
219   // "/usr/lib/debug/full/path/to/debug", not
220   // "/usr/lib/debug/to/debug"
221   llvm::sys::fs::make_absolute(OrigDir);
222   if (!FallbackDebugPath.empty()) {
223     // Try <FallbackDebugPath>/absolute/path/to/original_binary/debuglink_name
224     DebugPath = FallbackDebugPath;
225   } else {
226 #if defined(__NetBSD__)
227     // Try /usr/libdata/debug/absolute/path/to/original_binary/debuglink_name
228     DebugPath = "/usr/libdata/debug";
229 #else
230     // Try /usr/lib/debug/absolute/path/to/original_binary/debuglink_name
231     DebugPath = "/usr/lib/debug";
232 #endif
233   }
234   llvm::sys::path::append(DebugPath, llvm::sys::path::relative_path(OrigDir),
235                           DebuglinkName);
236   if (checkFileCRC(DebugPath, CRCHash)) {
237     Result = DebugPath.str();
238     return true;
239   }
240   return false;
241 }
242 
243 bool getGNUDebuglinkContents(const ObjectFile *Obj, std::string &DebugName,
244                              uint32_t &CRCHash) {
245   if (!Obj)
246     return false;
247   for (const SectionRef &Section : Obj->sections()) {
248     StringRef Name;
249     if (Expected<StringRef> NameOrErr = Section.getName())
250       Name = *NameOrErr;
251     else
252       consumeError(NameOrErr.takeError());
253 
254     Name = Name.substr(Name.find_first_not_of("._"));
255     if (Name == "gnu_debuglink") {
256       Expected<StringRef> ContentsOrErr = Section.getContents();
257       if (!ContentsOrErr) {
258         consumeError(ContentsOrErr.takeError());
259         return false;
260       }
261       DataExtractor DE(*ContentsOrErr, Obj->isLittleEndian(), 0);
262       uint64_t Offset = 0;
263       if (const char *DebugNameStr = DE.getCStr(&Offset)) {
264         // 4-byte align the offset.
265         Offset = (Offset + 3) & ~0x3;
266         if (DE.isValidOffsetForDataOfSize(Offset, 4)) {
267           DebugName = DebugNameStr;
268           CRCHash = DE.getU32(&Offset);
269           return true;
270         }
271       }
272       break;
273     }
274   }
275   return false;
276 }
277 
278 bool darwinDsymMatchesBinary(const MachOObjectFile *DbgObj,
279                              const MachOObjectFile *Obj) {
280   ArrayRef<uint8_t> dbg_uuid = DbgObj->getUuid();
281   ArrayRef<uint8_t> bin_uuid = Obj->getUuid();
282   if (dbg_uuid.empty() || bin_uuid.empty())
283     return false;
284   return !memcmp(dbg_uuid.data(), bin_uuid.data(), dbg_uuid.size());
285 }
286 
287 template <typename ELFT>
288 Optional<ArrayRef<uint8_t>> getBuildID(const ELFFile<ELFT> *Obj) {
289   if (!Obj)
290     return {};
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   }
304   return {};
305 }
306 
307 Optional<ArrayRef<uint8_t>> getBuildID(const ELFObjectFileBase *Obj) {
308   Optional<ArrayRef<uint8_t>> BuildID;
309   if (auto *O = dyn_cast<ELFObjectFile<ELF32LE>>(Obj))
310     BuildID = getBuildID(O->getELFFile());
311   else if (auto *O = dyn_cast<ELFObjectFile<ELF32BE>>(Obj))
312     BuildID = getBuildID(O->getELFFile());
313   else if (auto *O = dyn_cast<ELFObjectFile<ELF64LE>>(Obj))
314     BuildID = getBuildID(O->getELFFile());
315   else if (auto *O = dyn_cast<ELFObjectFile<ELF64BE>>(Obj))
316     BuildID = getBuildID(O->getELFFile());
317   else
318     llvm_unreachable("unsupported file format");
319   return BuildID;
320 }
321 
322 bool findDebugBinary(const std::vector<std::string> &DebugFileDirectory,
323                      const ArrayRef<uint8_t> BuildID,
324                      std::string &Result) {
325   auto getDebugPath = [&](StringRef Directory) {
326     SmallString<128> Path{Directory};
327     sys::path::append(Path, ".build-id",
328                       llvm::toHex(BuildID[0], /*LowerCase=*/true),
329                       llvm::toHex(BuildID.slice(1), /*LowerCase=*/true));
330     Path += ".debug";
331     return Path;
332   };
333   if (DebugFileDirectory.empty()) {
334     SmallString<128> Path = getDebugPath(
335 #if defined(__NetBSD__)
336       // Try /usr/libdata/debug/.build-id/../...
337       "/usr/libdata/debug"
338 #else
339       // Try /usr/lib/debug/.build-id/../...
340       "/usr/lib/debug"
341 #endif
342     );
343     if (llvm::sys::fs::exists(Path)) {
344       Result = Path.str();
345       return true;
346     }
347   } else {
348     for (const auto &Directory : DebugFileDirectory) {
349       // Try <debug-file-directory>/.build-id/../...
350       SmallString<128> Path = getDebugPath(Directory);
351       if (llvm::sys::fs::exists(Path)) {
352         Result = Path.str();
353         return true;
354       }
355     }
356   }
357   return false;
358 }
359 
360 } // end anonymous namespace
361 
362 ObjectFile *LLVMSymbolizer::lookUpDsymFile(const std::string &ExePath,
363     const MachOObjectFile *MachExeObj, const std::string &ArchName) {
364   // On Darwin we may find DWARF in separate object file in
365   // resource directory.
366   std::vector<std::string> DsymPaths;
367   StringRef Filename = sys::path::filename(ExePath);
368   DsymPaths.push_back(getDarwinDWARFResourceForPath(ExePath, Filename));
369   for (const auto &Path : Opts.DsymHints) {
370     DsymPaths.push_back(getDarwinDWARFResourceForPath(Path, Filename));
371   }
372   for (const auto &Path : DsymPaths) {
373     auto DbgObjOrErr = getOrCreateObject(Path, ArchName);
374     if (!DbgObjOrErr) {
375       // Ignore errors, the file might not exist.
376       consumeError(DbgObjOrErr.takeError());
377       continue;
378     }
379     ObjectFile *DbgObj = DbgObjOrErr.get();
380     if (!DbgObj)
381       continue;
382     const MachOObjectFile *MachDbgObj = dyn_cast<const MachOObjectFile>(DbgObj);
383     if (!MachDbgObj)
384       continue;
385     if (darwinDsymMatchesBinary(MachDbgObj, MachExeObj))
386       return DbgObj;
387   }
388   return nullptr;
389 }
390 
391 ObjectFile *LLVMSymbolizer::lookUpDebuglinkObject(const std::string &Path,
392                                                   const ObjectFile *Obj,
393                                                   const std::string &ArchName) {
394   std::string DebuglinkName;
395   uint32_t CRCHash;
396   std::string DebugBinaryPath;
397   if (!getGNUDebuglinkContents(Obj, DebuglinkName, CRCHash))
398     return nullptr;
399   if (!findDebugBinary(Path, DebuglinkName, CRCHash, Opts.FallbackDebugPath,
400                        DebugBinaryPath))
401     return nullptr;
402   auto DbgObjOrErr = getOrCreateObject(DebugBinaryPath, ArchName);
403   if (!DbgObjOrErr) {
404     // Ignore errors, the file might not exist.
405     consumeError(DbgObjOrErr.takeError());
406     return nullptr;
407   }
408   return DbgObjOrErr.get();
409 }
410 
411 ObjectFile *LLVMSymbolizer::lookUpBuildIDObject(const std::string &Path,
412                                                 const ELFObjectFileBase *Obj,
413                                                 const std::string &ArchName) {
414   auto BuildID = getBuildID(Obj);
415   if (!BuildID)
416     return nullptr;
417   if (BuildID->size() < 2)
418     return nullptr;
419   std::string DebugBinaryPath;
420   if (!findDebugBinary(Opts.DebugFileDirectory, *BuildID, DebugBinaryPath))
421     return nullptr;
422   auto DbgObjOrErr = getOrCreateObject(DebugBinaryPath, ArchName);
423   if (!DbgObjOrErr) {
424     consumeError(DbgObjOrErr.takeError());
425     return nullptr;
426   }
427   return DbgObjOrErr.get();
428 }
429 
430 Expected<LLVMSymbolizer::ObjectPair>
431 LLVMSymbolizer::getOrCreateObjectPair(const std::string &Path,
432                                       const std::string &ArchName) {
433   auto I = ObjectPairForPathArch.find(std::make_pair(Path, ArchName));
434   if (I != ObjectPairForPathArch.end())
435     return I->second;
436 
437   auto ObjOrErr = getOrCreateObject(Path, ArchName);
438   if (!ObjOrErr) {
439     ObjectPairForPathArch.emplace(std::make_pair(Path, ArchName),
440                                   ObjectPair(nullptr, nullptr));
441     return ObjOrErr.takeError();
442   }
443 
444   ObjectFile *Obj = ObjOrErr.get();
445   assert(Obj != nullptr);
446   ObjectFile *DbgObj = nullptr;
447 
448   if (auto MachObj = dyn_cast<const MachOObjectFile>(Obj))
449     DbgObj = lookUpDsymFile(Path, MachObj, ArchName);
450   else if (auto ELFObj = dyn_cast<const ELFObjectFileBase>(Obj))
451     DbgObj = lookUpBuildIDObject(Path, ELFObj, ArchName);
452   if (!DbgObj)
453     DbgObj = lookUpDebuglinkObject(Path, Obj, ArchName);
454   if (!DbgObj)
455     DbgObj = Obj;
456   ObjectPair Res = std::make_pair(Obj, DbgObj);
457   ObjectPairForPathArch.emplace(std::make_pair(Path, ArchName), Res);
458   return Res;
459 }
460 
461 Expected<ObjectFile *>
462 LLVMSymbolizer::getOrCreateObject(const std::string &Path,
463                                   const std::string &ArchName) {
464   Binary *Bin;
465   auto Pair = BinaryForPath.emplace(Path, OwningBinary<Binary>());
466   if (!Pair.second) {
467     Bin = Pair.first->second.getBinary();
468   } else {
469     Expected<OwningBinary<Binary>> BinOrErr = createBinary(Path);
470     if (!BinOrErr)
471       return BinOrErr.takeError();
472     Pair.first->second = std::move(BinOrErr.get());
473     Bin = Pair.first->second.getBinary();
474   }
475 
476   if (!Bin)
477     return static_cast<ObjectFile *>(nullptr);
478 
479   if (MachOUniversalBinary *UB = dyn_cast_or_null<MachOUniversalBinary>(Bin)) {
480     auto I = ObjectForUBPathAndArch.find(std::make_pair(Path, ArchName));
481     if (I != ObjectForUBPathAndArch.end())
482       return I->second.get();
483 
484     Expected<std::unique_ptr<ObjectFile>> ObjOrErr =
485         UB->getMachOObjectForArch(ArchName);
486     if (!ObjOrErr) {
487       ObjectForUBPathAndArch.emplace(std::make_pair(Path, ArchName),
488                                      std::unique_ptr<ObjectFile>());
489       return ObjOrErr.takeError();
490     }
491     ObjectFile *Res = ObjOrErr->get();
492     ObjectForUBPathAndArch.emplace(std::make_pair(Path, ArchName),
493                                    std::move(ObjOrErr.get()));
494     return Res;
495   }
496   if (Bin->isObject()) {
497     return cast<ObjectFile>(Bin);
498   }
499   return errorCodeToError(object_error::arch_not_found);
500 }
501 
502 Expected<SymbolizableModule *>
503 LLVMSymbolizer::createModuleInfo(const ObjectFile *Obj,
504                                  std::unique_ptr<DIContext> Context,
505                                  StringRef ModuleName) {
506   auto InfoOrErr = SymbolizableObjectFile::create(Obj, std::move(Context),
507                                                   Opts.UntagAddresses);
508   std::unique_ptr<SymbolizableModule> SymMod;
509   if (InfoOrErr)
510     SymMod = std::move(*InfoOrErr);
511   auto InsertResult =
512       Modules.insert(std::make_pair(ModuleName, std::move(SymMod)));
513   assert(InsertResult.second);
514   if (std::error_code EC = InfoOrErr.getError())
515     return errorCodeToError(EC);
516   return InsertResult.first->second.get();
517 }
518 
519 Expected<SymbolizableModule *>
520 LLVMSymbolizer::getOrCreateModuleInfo(const std::string &ModuleName) {
521   auto I = Modules.find(ModuleName);
522   if (I != Modules.end())
523     return I->second.get();
524 
525   std::string BinaryName = ModuleName;
526   std::string ArchName = Opts.DefaultArch;
527   size_t ColonPos = ModuleName.find_last_of(':');
528   // Verify that substring after colon form a valid arch name.
529   if (ColonPos != std::string::npos) {
530     std::string ArchStr = ModuleName.substr(ColonPos + 1);
531     if (Triple(ArchStr).getArch() != Triple::UnknownArch) {
532       BinaryName = ModuleName.substr(0, ColonPos);
533       ArchName = ArchStr;
534     }
535   }
536   auto ObjectsOrErr = getOrCreateObjectPair(BinaryName, ArchName);
537   if (!ObjectsOrErr) {
538     // Failed to find valid object file.
539     Modules.emplace(ModuleName, std::unique_ptr<SymbolizableModule>());
540     return ObjectsOrErr.takeError();
541   }
542   ObjectPair Objects = ObjectsOrErr.get();
543 
544   std::unique_ptr<DIContext> Context;
545   // If this is a COFF object containing PDB info, use a PDBContext to
546   // symbolize. Otherwise, use DWARF.
547   if (auto CoffObject = dyn_cast<COFFObjectFile>(Objects.first)) {
548     const codeview::DebugInfo *DebugInfo;
549     StringRef PDBFileName;
550     auto EC = CoffObject->getDebugPDBInfo(DebugInfo, PDBFileName);
551     if (!EC && DebugInfo != nullptr && !PDBFileName.empty()) {
552 #if 0
553       using namespace pdb;
554       std::unique_ptr<IPDBSession> Session;
555       if (auto Err = loadDataForEXE(PDB_ReaderType::DIA,
556                                     Objects.first->getFileName(), Session)) {
557         Modules.emplace(ModuleName, std::unique_ptr<SymbolizableModule>());
558         // Return along the PDB filename to provide more context
559         return createFileError(PDBFileName, std::move(Err));
560       }
561       Context.reset(new PDBContext(*CoffObject, std::move(Session)));
562 #else
563       return make_error<StringError>(
564           "PDB support not compiled in",
565           std::make_error_code(std::errc::not_supported));
566 #endif
567     }
568   }
569   if (!Context)
570     Context =
571         DWARFContext::create(*Objects.second, nullptr,
572                              DWARFContext::defaultErrorHandler, Opts.DWPName);
573   return createModuleInfo(Objects.first, std::move(Context), ModuleName);
574 }
575 
576 namespace {
577 
578 // Undo these various manglings for Win32 extern "C" functions:
579 // cdecl       - _foo
580 // stdcall     - _foo@12
581 // fastcall    - @foo@12
582 // vectorcall  - foo@@12
583 // These are all different linkage names for 'foo'.
584 StringRef demanglePE32ExternCFunc(StringRef SymbolName) {
585   // Remove any '_' or '@' prefix.
586   char Front = SymbolName.empty() ? '\0' : SymbolName[0];
587   if (Front == '_' || Front == '@')
588     SymbolName = SymbolName.drop_front();
589 
590   // Remove any '@[0-9]+' suffix.
591   if (Front != '?') {
592     size_t AtPos = SymbolName.rfind('@');
593     if (AtPos != StringRef::npos &&
594         std::all_of(SymbolName.begin() + AtPos + 1, SymbolName.end(),
595                     [](char C) { return C >= '0' && C <= '9'; })) {
596       SymbolName = SymbolName.substr(0, AtPos);
597     }
598   }
599 
600   // Remove any ending '@' for vectorcall.
601   if (SymbolName.endswith("@"))
602     SymbolName = SymbolName.drop_back();
603 
604   return SymbolName;
605 }
606 
607 } // end anonymous namespace
608 
609 std::string
610 LLVMSymbolizer::DemangleName(const std::string &Name,
611                              const SymbolizableModule *DbiModuleDescriptor) {
612   // We can spoil names of symbols with C linkage, so use an heuristic
613   // approach to check if the name should be demangled.
614   if (Name.substr(0, 2) == "_Z") {
615     int status = 0;
616     char *DemangledName = itaniumDemangle(Name.c_str(), nullptr, nullptr, &status);
617     if (status != 0)
618       return Name;
619     std::string Result = DemangledName;
620     free(DemangledName);
621     return Result;
622   }
623 
624   if (!Name.empty() && Name.front() == '?') {
625     // Only do MSVC C++ demangling on symbols starting with '?'.
626     int status = 0;
627     char *DemangledName = microsoftDemangle(
628         Name.c_str(), nullptr, nullptr, &status,
629         MSDemangleFlags(MSDF_NoAccessSpecifier | MSDF_NoCallingConvention |
630                         MSDF_NoMemberType | MSDF_NoReturnType));
631     if (status != 0)
632       return Name;
633     std::string Result = DemangledName;
634     free(DemangledName);
635     return Result;
636   }
637 
638   if (DbiModuleDescriptor && DbiModuleDescriptor->isWin32Module())
639     return std::string(demanglePE32ExternCFunc(Name));
640   return Name;
641 }
642 
643 } // namespace symbolize
644 } // namespace llvm
645