[Serialization] In ASTReader::getInputFile record it when we didn't find the file to avoid looking it up again.

Hopefully addresses rdar://14514222.

llvm-svn: 198781

2 files changed, 15 insertions, 2 deletions

diff --git a/clang/include/clang/Serialization/Module.h b/clang/include/clang/Serialization/Module.h
index 89c604f393e..f4c07553d6b 100644
--- a/clang/include/clang/Serialization/Module.h
+++ b/clang/include/clang/Serialization/Module.h
@@ -57,11 +57,12 @@ struct DeclContextInfo {
 
 /// \brief The input file that has been loaded from this AST file, along with
 /// bools indicating whether this was an overridden buffer or if it was
-/// out-of-date.
+/// out-of-date or not-found.
 class InputFile {
   enum {
     Overridden = 1,
-    OutOfDate = 2
+    OutOfDate = 2,
+    NotFound = 3
   };
   llvm::PointerIntPair<const FileEntry *, 2, unsigned> Val;
 
@@ -79,9 +80,16 @@ public:
     Val.setPointerAndInt(File, intVal);
   }
 
+  static InputFile getNotFound() {
+    InputFile File;
+    File.Val.setInt(NotFound);
+    return File;
+  }
+
   const FileEntry *getFile() const { return Val.getPointer(); }
   bool isOverridden() const { return Val.getInt() == Overridden; }
   bool isOutOfDate() const { return Val.getInt() == OutOfDate; }
+  bool isNotFound() const { return Val.getInt() == NotFound; }
 };
 
 /// \brief Information about a module that has been loaded by the ASTReader.
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index c531134a974..400619f63ab 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -1643,6 +1643,9 @@ InputFile ASTReader::getInputFile(ModuleFile &F, unsigned ID, bool Complain) {
   if (F.InputFilesLoaded[ID-1].getFile())
     return F.InputFilesLoaded[ID-1];
 
+  if (F.InputFilesLoaded[ID-1].isNotFound())
+    return InputFile();
+
   // Go find this input file.
   BitstreamCursor &Cursor = F.InputFilesCursor;
   SavedStreamPosition SavedPosition(Cursor);
@@ -1692,6 +1695,8 @@ InputFile ASTReader::getInputFile(ModuleFile &F, unsigned ID, bool Complain) {
         ErrorStr += "' referenced by AST file";
         Error(ErrorStr.c_str());
       }
+      // Record that we didn't find the file.
+      F.InputFilesLoaded[ID-1] = InputFile::getNotFound();
       return InputFile();
     }