3 files changed, 20 insertions, 13 deletions
diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index f12f6303f0d..267d318fa98 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -870,8 +870,9 @@ static void compileModuleImpl(CompilerInstance &ImportingInstance,
     SourceMgr.overrideFileContents(ModuleMapFile, ModuleMapBuffer);
   }
 
-  // Construct a module-generating action.
-  GenerateModuleAction CreateModuleAction(Module->IsSystem);
+  // Construct a module-generating action. Passing through Module->ModuleMap is
+  // safe because the FileManager is shared between the compiler instances.
+  GenerateModuleAction CreateModuleAction(Module->ModuleMap, Module->IsSystem);
   
   // Execute the action to actually build the module in-place. Use a separate
   // thread so that we get a stack large enough.
diff --git a/clang/lib/Frontend/FrontendAction.cpp b/clang/lib/Frontend/FrontendAction.cpp
index d2ece7e732d..dc4dd89371a 100644
--- a/clang/lib/Frontend/FrontendAction.cpp
+++ b/clang/lib/Frontend/FrontendAction.cpp
@@ -256,6 +256,10 @@ bool FrontendAction::BeginSourceFile(CompilerInstance &CI,
     if (!BeginSourceFileAction(CI, InputFile))
       goto failure;
 
+    // Initialize the main file entry.
+    if (!CI.InitializeSourceManager(CurrentInput))
+      goto failure;
+
     return true;
   }
 
@@ -302,6 +306,11 @@ bool FrontendAction::BeginSourceFile(CompilerInstance &CI,
   if (!BeginSourceFileAction(CI, InputFile))
     goto failure;
 
+  // Initialize the main file entry. It is important that this occurs after
+  // BeginSourceFileAction, which may change CurrentInput during module builds.
+  if (!CI.InitializeSourceManager(CurrentInput))
+    goto failure;
+
   // Create the AST context and consumer unless this is a preprocessor only
   // action.
   if (!usesPreprocessorOnly()) {
@@ -389,13 +398,6 @@ bool FrontendAction::BeginSourceFile(CompilerInstance &CI,
 bool FrontendAction::Execute() {
   CompilerInstance &CI = getCompilerInstance();
 
-  // Initialize the main file entry. This needs to be delayed until after PCH
-  // has loaded.
-  if (!isCurrentFileAST()) {
-    if (!CI.InitializeSourceManager(getCurrentInput()))
-      return false;
-  }
-
   if (CI.hasFrontendTimer()) {
     llvm::TimeRegion Timer(CI.getFrontendTimer());
     ExecuteAction();
diff --git a/clang/lib/Frontend/FrontendActions.cpp b/clang/lib/Frontend/FrontendActions.cpp
index 3f1d2c6106f..bbd2dff46c0 100644
--- a/clang/lib/Frontend/FrontendActions.cpp
+++ b/clang/lib/Frontend/FrontendActions.cpp
@@ -299,6 +299,11 @@ bool GenerateModuleAction::BeginSourceFileAction(CompilerInstance &CI,
     return false;
   }
 
+  if (!ModuleMapForUniquing)
+    ModuleMapForUniquing = ModuleMap;
+  Module->ModuleMap = ModuleMapForUniquing;
+  assert(Module->ModuleMap && "missing module map file");
+
   FileManager &FileMgr = CI.getFileManager();
 
   // Collect the set of #includes we need to build the module.
@@ -337,10 +342,9 @@ bool GenerateModuleAction::ComputeASTConsumerArguments(CompilerInstance &CI,
   // in the module cache.
   if (CI.getFrontendOpts().OutputFile.empty()) {
     HeaderSearch &HS = CI.getPreprocessor().getHeaderSearchInfo();
-    SmallString<256> ModuleFileName(HS.getModuleCachePath());
-    llvm::sys::path::append(ModuleFileName, 
-                            CI.getLangOpts().CurrentModule + ".pcm");
-    CI.getFrontendOpts().OutputFile = ModuleFileName.str();
+    CI.getFrontendOpts().OutputFile =
+        HS.getModuleFileName(CI.getLangOpts().CurrentModule,
+                             ModuleMapForUniquing->getName());
   }
   
   // We use createOutputFile here because this is exposed via libclang, and we