[Symbolize] Check if the PE file has a PDB and emit an error if we can't load it

Summary:
Previously we would try to load PDBs for every PE executable we tried to
symbolize. If that failed, we would fall back to DWARF. If there wasn't
any DWARF, we'd print mostly useless symbol information using the export
table.

With this change, we only try to load PDBs for executables that claim to
have them. If that fails, we can now print an error rather than falling
back silently. This should make it a lot easier to diagnose and fix
common symbolization issues, such as not having DIA or not having a PDB.

Reviewers: zturner, eugenis

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D20982

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@271725 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 90 insertions, 64 deletions

diff --git a/lib/DebugInfo/Symbolize/Symbolize.cpp b/lib/DebugInfo/Symbolize/Symbolize.cpp
index 9c12169fb67..e2732bf819e 100644
--- a/lib/DebugInfo/Symbolize/Symbolize.cpp
+++ b/lib/DebugInfo/Symbolize/Symbolize.cpp
@@ -50,12 +50,18 @@
 namespace llvm {
 namespace symbolize {
 
-ErrorOr<DILineInfo> LLVMSymbolizer::symbolizeCode(const std::string &ModuleName,
+Expected<DILineInfo> LLVMSymbolizer::symbolizeCode(const std::string &ModuleName,
                                                   uint64_t ModuleOffset) {
-  auto InfoOrErr = getOrCreateModuleInfo(ModuleName);
-  if (auto EC = InfoOrErr.getError())
-    return EC;
-  SymbolizableModule *Info = InfoOrErr.get();
+  SymbolizableModule *Info;
+  if (auto InfoOrErr = getOrCreateModuleInfo(ModuleName))
+    Info = InfoOrErr.get();
+  else
+    return InfoOrErr.takeError();
+
+  // A null module means an error has already been reported. Return an empty
+  // result.
+  if (!Info)
+    return DILineInfo();
 
   // If the user is giving us relative addresses, add the preferred base of the
   // object to the offset before we do the query. It's what DIContext expects.
@@ -69,13 +75,19 @@ ErrorOr<DILineInfo> LLVMSymbolizer::symbolizeCode(const std::string &ModuleName,
   return LineInfo;
 }
 
-ErrorOr<DIInliningInfo>
+Expected<DIInliningInfo>
 LLVMSymbolizer::symbolizeInlinedCode(const std::string &ModuleName,
                                      uint64_t ModuleOffset) {
-  auto InfoOrErr = getOrCreateModuleInfo(ModuleName);
-  if (auto EC = InfoOrErr.getError())
-    return EC;
-  SymbolizableModule *Info = InfoOrErr.get();
+  SymbolizableModule *Info;
+  if (auto InfoOrErr = getOrCreateModuleInfo(ModuleName))
+    Info = InfoOrErr.get();
+  else
+    return InfoOrErr.takeError();
+
+  // A null module means an error has already been reported. Return an empty
+  // result.
+  if (!Info)
+    return DIInliningInfo();
 
   // If the user is giving us relative addresses, add the preferred base of the
   // object to the offset before we do the query. It's what DIContext expects.
@@ -93,12 +105,18 @@ LLVMSymbolizer::symbolizeInlinedCode(const std::string &ModuleName,
   return InlinedContext;
 }
 
-ErrorOr<DIGlobal> LLVMSymbolizer::symbolizeData(const std::string &ModuleName,
-                                                uint64_t ModuleOffset) {
-  auto InfoOrErr = getOrCreateModuleInfo(ModuleName);
-  if (auto EC = InfoOrErr.getError())
-    return EC;
-  SymbolizableModule *Info = InfoOrErr.get();
+Expected<DIGlobal> LLVMSymbolizer::symbolizeData(const std::string &ModuleName,
+                                                 uint64_t ModuleOffset) {
+  SymbolizableModule *Info;
+  if (auto InfoOrErr = getOrCreateModuleInfo(ModuleName))
+    Info = InfoOrErr.get();
+  else
+    return InfoOrErr.takeError();
+
+  // A null module means an error has already been reported. Return an empty
+  // result.
+  if (!Info)
+    return DIGlobal();
 
   // If the user is giving us relative addresses, add the preferred base of
   // the object to the offset before we do the query. It's what DIContext
@@ -232,9 +250,14 @@ ObjectFile *LLVMSymbolizer::lookUpDsymFile(const std::string &ExePath,
   }
   for (const auto &Path : DsymPaths) {
     auto DbgObjOrErr = getOrCreateObject(Path, ArchName);
-    if (!DbgObjOrErr)
+    if (!DbgObjOrErr) {
+      // Ignore errors, the file might not exist.
+      consumeError(DbgObjOrErr.takeError());
       continue;
+    }
     ObjectFile *DbgObj = DbgObjOrErr.get();
+    if (!DbgObj)
+      continue;
     const MachOObjectFile *MachDbgObj = dyn_cast<const MachOObjectFile>(DbgObj);
     if (!MachDbgObj)
       continue;
@@ -255,23 +278,27 @@ ObjectFile *LLVMSymbolizer::lookUpDebuglinkObject(const std::string &Path,
   if (!findDebugBinary(Path, DebuglinkName, CRCHash, DebugBinaryPath))
     return nullptr;
   auto DbgObjOrErr = getOrCreateObject(DebugBinaryPath, ArchName);
-  if (!DbgObjOrErr)
+  if (!DbgObjOrErr) {
+    // Ignore errors, the file might not exist.
+    consumeError(DbgObjOrErr.takeError());
     return nullptr;
+  }
   return DbgObjOrErr.get();
 }
 
-ErrorOr<LLVMSymbolizer::ObjectPair>
+Expected<LLVMSymbolizer::ObjectPair>
 LLVMSymbolizer::getOrCreateObjectPair(const std::string &Path,
                                       const std::string &ArchName) {
   const auto &I = ObjectPairForPathArch.find(std::make_pair(Path, ArchName));
-  if (I != ObjectPairForPathArch.end())
+  if (I != ObjectPairForPathArch.end()) {
     return I->second;
+  }
 
   auto ObjOrErr = getOrCreateObject(Path, ArchName);
-  if (auto EC = ObjOrErr.getError()) {
-    ObjectPairForPathArch.insert(
-        std::make_pair(std::make_pair(Path, ArchName), EC));
-    return EC;
+  if (!ObjOrErr) {
+    ObjectPairForPathArch.insert(std::make_pair(std::make_pair(Path, ArchName),
+                                                ObjectPair(nullptr, nullptr)));
+    return ObjOrErr.takeError();
   }
 
   ObjectFile *Obj = ObjOrErr.get();
@@ -290,7 +317,7 @@ LLVMSymbolizer::getOrCreateObjectPair(const std::string &Path,
   return Res;
 }
 
-ErrorOr<ObjectFile *>
+Expected<ObjectFile *>
 LLVMSymbolizer::getOrCreateObject(const std::string &Path,
                                   const std::string &ArchName) {
   const auto &I = BinaryForPath.find(Path);
@@ -298,34 +325,29 @@ LLVMSymbolizer::getOrCreateObject(const std::string &Path,
   if (I == BinaryForPath.end()) {
     Expected<OwningBinary<Binary>> BinOrErr = createBinary(Path);
     if (!BinOrErr) {
-      auto EC = errorToErrorCode(BinOrErr.takeError());
-      BinaryForPath.insert(std::make_pair(Path, EC));
-      return EC;
+      BinaryForPath.insert({Path, OwningBinary<Binary>()});
+      return BinOrErr.takeError();
     }
     Bin = BinOrErr->getBinary();
     BinaryForPath.insert(std::make_pair(Path, std::move(BinOrErr.get())));
-  } else if (auto EC = I->second.getError()) {
-    return EC;
   } else {
-    Bin = I->second->getBinary();
+    Bin = I->second.getBinary();
   }
 
-  assert(Bin != nullptr);
+  if (!Bin)
+    return static_cast<ObjectFile *>(nullptr);
 
-  if (MachOUniversalBinary *UB = dyn_cast<MachOUniversalBinary>(Bin)) {
+  if (MachOUniversalBinary *UB = dyn_cast_or_null<MachOUniversalBinary>(Bin)) {
     const auto &I = ObjectForUBPathAndArch.find(std::make_pair(Path, ArchName));
     if (I != ObjectForUBPathAndArch.end()) {
-      if (auto EC = I->second.getError())
-        return EC;
-      return I->second->get();
+      return I->second.get();
     }
     Expected<std::unique_ptr<ObjectFile>> ObjOrErr =
         UB->getObjectForArch(ArchName);
     if (!ObjOrErr) {
-      auto EC = errorToErrorCode(ObjOrErr.takeError());
-      ObjectForUBPathAndArch.insert(
-          std::make_pair(std::make_pair(Path, ArchName), EC));
-      return EC;
+      ObjectForUBPathAndArch.insert(std::make_pair(
+          std::make_pair(Path, ArchName), std::unique_ptr<ObjectFile>()));
+      return ObjOrErr.takeError();
     }
     ObjectFile *Res = ObjOrErr->get();
     ObjectForUBPathAndArch.insert(std::make_pair(std::make_pair(Path, ArchName),
@@ -335,17 +357,14 @@ LLVMSymbolizer::getOrCreateObject(const std::string &Path,
   if (Bin->isObject()) {
     return cast<ObjectFile>(Bin);
   }
-  return object_error::arch_not_found;
+  return errorCodeToError(object_error::arch_not_found);
 }
 
-ErrorOr<SymbolizableModule *>
+Expected<SymbolizableModule *>
 LLVMSymbolizer::getOrCreateModuleInfo(const std::string &ModuleName) {
   const auto &I = Modules.find(ModuleName);
   if (I != Modules.end()) {
-    auto &InfoOrErr = I->second;
-    if (auto EC = InfoOrErr.getError())
-      return EC;
-    return InfoOrErr->get();
+    return I->second.get();
   }
   std::string BinaryName = ModuleName;
   std::string ArchName = Opts.DefaultArch;
@@ -359,27 +378,31 @@ LLVMSymbolizer::getOrCreateModuleInfo(const std::string &ModuleName) {
     }
   }
   auto ObjectsOrErr = getOrCreateObjectPair(BinaryName, ArchName);
-  if (auto EC = ObjectsOrErr.getError()) {
+  if (!ObjectsOrErr) {
     // Failed to find valid object file.
-    Modules.insert(std::make_pair(ModuleName, EC));
-    return EC;
+    Modules.insert(
+        std::make_pair(ModuleName, std::unique_ptr<SymbolizableModule>()));
+    return ObjectsOrErr.takeError();
   }
   ObjectPair Objects = ObjectsOrErr.get();
 
   std::unique_ptr<DIContext> Context;
+  // If this is a COFF object containing PDB info, use a PDBContext to
+  // symbolize. Otherwise, use DWARF.
   if (auto CoffObject = dyn_cast<COFFObjectFile>(Objects.first)) {
-    using namespace pdb;
-    // If this is a COFF object, assume it contains PDB debug information.  If
-    // we don't find any we will fall back to the DWARF case.
-    std::unique_ptr<IPDBSession> Session;
-    auto Error = loadDataForEXE(
-        PDB_ReaderType::DIA, Objects.first->getFileName(), Session);
-    if (!Error) {
+    const debug_pdb_info *PDBInfo;
+    StringRef PDBFileName;
+    auto EC = CoffObject->getDebugPDBInfo(PDBInfo, PDBFileName);
+    if (!EC && PDBInfo != nullptr) {
+      using namespace pdb;
+      std::unique_ptr<IPDBSession> Session;
+      if (auto Err = loadDataForEXE(PDB_ReaderType::DIA,
+                                    Objects.first->getFileName(), Session)) {
+        Modules.insert(
+            std::make_pair(ModuleName, std::unique_ptr<SymbolizableModule>()));
+        return std::move(Err);
+      }
       Context.reset(new PDBContext(*CoffObject, std::move(Session)));
-    } else {
-      // Drop error
-      handleAllErrors(std::move(Error),
-                      [](const ErrorInfoBase &) { return Error::success(); });
     }
   }
   if (!Context)
@@ -387,12 +410,15 @@ LLVMSymbolizer::getOrCreateModuleInfo(const std::string &ModuleName) {
   assert(Context);
   auto InfoOrErr =
       SymbolizableObjectFile::create(Objects.first, std::move(Context));
+  std::unique_ptr<SymbolizableModule> SymMod;
+  if (InfoOrErr)
+    SymMod = std::move(InfoOrErr.get());
   auto InsertResult =
-      Modules.insert(std::make_pair(ModuleName, std::move(InfoOrErr)));
+      Modules.insert(std::make_pair(ModuleName, std::move(SymMod)));
   assert(InsertResult.second);
-  if (auto EC = InsertResult.first->second.getError())
-    return EC;
-  return InsertResult.first->second->get();
+  if (auto EC = InfoOrErr.getError())
+    return errorCodeToError(EC);
+  return InsertResult.first->second.get();
 }
 
 namespace {