1 files changed, 66 insertions, 38 deletions

diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index d81e9d8a36..840b665cd7 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -2831,37 +2831,33 @@ ASTReader::ASTReadResult ASTReader::ReadAST(const std::string &FileName,
 ASTReader::ASTReadResult ASTReader::ReadASTCore(StringRef FileName,
                                                 ModuleKind Type,
                                                 Module *ImportedBy) {
-  Module &F = ModuleMgr.addModule(FileName, Type, ImportedBy);
+  Module *M;
+  bool NewModule;
+  std::string ErrorStr;
+  llvm::tie(M, NewModule) = ModuleMgr.addModule(FileName, Type, ImportedBy,
+                                                ErrorStr);
+
+  if (!M) {
+    // We couldn't load the module.
+    std::string Msg = "Unable to load module \"" + FileName.str() + "\": "
+      + ErrorStr;
+    Error(Msg);
+    return Failure;
+  }
+
+  if (!NewModule) {
+    // We've already loaded this module.
+    return Success;
+  }
 
+  // FIXME: This seems rather a hack. Should CurrentDir be part of the
+  // module?
   if (FileName != "-") {
     CurrentDir = llvm::sys::path::parent_path(FileName);
     if (CurrentDir.empty()) CurrentDir = ".";
   }
 
-  if (llvm::MemoryBuffer *Buffer = ModuleMgr.lookupBuffer(FileName)) {
-    F.Buffer.reset(Buffer);
-    assert(F.Buffer && "Passed null buffer");
-  } else {
-    // Open the AST file.
-    //
-    // FIXME: This shouldn't be here, we should just take a raw_ostream.
-    std::string ErrStr;
-    llvm::error_code ec;
-    if (FileName == "-") {
-      ec = llvm::MemoryBuffer::getSTDIN(F.Buffer);
-      if (ec)
-        ErrStr = ec.message();
-    } else
-      F.Buffer.reset(FileMgr.getBufferForFile(FileName, &ErrStr));
-    if (!F.Buffer) {
-      Error(ErrStr.c_str());
-      return IgnorePCH;
-    }
-  }
-
-  // Initialize the stream
-  F.StreamFile.init((const unsigned char *)F.Buffer->getBufferStart(),
-                    (const unsigned char *)F.Buffer->getBufferEnd());
+  Module &F = *M;
   llvm::BitstreamCursor &Stream = F.Stream;
   Stream.init(F.StreamFile);
   F.SizeInBits = F.Buffer->getBufferSize() * 8;
@@ -5709,25 +5705,57 @@ llvm::MemoryBuffer *ModuleManager::lookupBuffer(StringRef Name) {
   return InMemoryBuffers[Entry];
 }
 
-/// \brief Creates a new module and adds it to the list of known modules
-Module &ModuleManager::addModule(StringRef FileName, ModuleKind Type,
-                                 Module *ImportedBy) {
-  Module *Current = new Module(Type);
-  Current->FileName = FileName.str();
-  Chain.push_back(Current);
-
+std::pair<Module *, bool>
+ModuleManager::addModule(StringRef FileName, ModuleKind Type, 
+                         Module *ImportedBy, std::string &ErrorStr) {
   const FileEntry *Entry = FileMgr.getFile(FileName);
-  // FIXME: Check whether we already loaded this module, before 
-  Modules[Entry] = Current;
+  if (!Entry && FileName != "-") {
+    ErrorStr = "file not found";
+    return std::make_pair(static_cast<Module*>(0), false);
+  }
+
+  // Check whether we already loaded this module, before 
+  Module *&ModuleEntry = Modules[Entry];
+  bool NewModule = false;
+  if (!ModuleEntry) {
+    // Allocate a new module.
+    Module *New = new Module(Type);
+    New->FileName = FileName.str();
+    Chain.push_back(New);
+    NewModule = true;
+    ModuleEntry = New;
+
+    // Load the contents of the module
+    if (llvm::MemoryBuffer *Buffer = lookupBuffer(FileName)) {
+      // The buffer was already provided for us.
+      assert(Buffer && "Passed null buffer");
+      New->Buffer.reset(Buffer);
+    } else {
+      // Open the AST file.
+      llvm::error_code ec;
+      if (FileName == "-") {
+        ec = llvm::MemoryBuffer::getSTDIN(New->Buffer);
+        if (ec)
+          ErrorStr = ec.message();
+      } else
+        New->Buffer.reset(FileMgr.getBufferForFile(FileName, &ErrorStr));
+
+      if (!New->Buffer)
+        return std::make_pair(static_cast<Module*>(0), false);
+    }
+
+    // Initialize the stream
+    New->StreamFile.init((const unsigned char *)New->Buffer->getBufferStart(),
+                         (const unsigned char *)New->Buffer->getBufferEnd());     }
 
   if (ImportedBy) {
-    Current->ImportedBy.insert(ImportedBy);
-    ImportedBy->Imports.insert(Current);
+    ModuleEntry->ImportedBy.insert(ImportedBy);
+    ImportedBy->Imports.insert(ModuleEntry);
   } else {
-    Current->DirectlyImported = true;
+    ModuleEntry->DirectlyImported = true;
   }
   
-  return *Current;
+  return std::make_pair(ModuleEntry, NewModule);
 }
 
 void ModuleManager::addInMemoryBuffer(StringRef FileName,