[modules] Write the options records to a separate subblock rather than writing

them directly to the control block. These are fairly large, and in a build with
lots of modules / chained PCH, we don't need to read most of them. No
functionality change intended.

llvm-svn: 247055

1 files changed, 10 insertions, 2 deletions

diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 225a00c942f..dfcc539284b 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -881,12 +881,14 @@ void ASTWriter::WriteBlockInfoBlock() {
   RECORD(MODULE_DIRECTORY);
   RECORD(MODULE_MAP_FILE);
   RECORD(IMPORTS);
-  RECORD(LANGUAGE_OPTIONS);
-  RECORD(TARGET_OPTIONS);
   RECORD(ORIGINAL_FILE);
   RECORD(ORIGINAL_PCH_DIR);
   RECORD(ORIGINAL_FILE_ID);
   RECORD(INPUT_FILE_OFFSETS);
+
+  BLOCK(OPTIONS_BLOCK);
+  RECORD(LANGUAGE_OPTIONS);
+  RECORD(TARGET_OPTIONS);
   RECORD(DIAGNOSTIC_OPTIONS);
   RECORD(FILE_SYSTEM_OPTIONS);
   RECORD(HEADER_SEARCH_OPTIONS);
@@ -1288,6 +1290,9 @@ void ASTWriter::WriteControlBlock(Preprocessor &PP, ASTContext &Context,
     Stream.EmitRecord(IMPORTS, Record);
   }
 
+  // Write the options block.
+  Stream.EnterSubblock(OPTIONS_BLOCK_ID, 4);
+
   // Language options.
   Record.clear();
   const LangOptions &LangOpts = Context.getLangOpts();
@@ -1427,6 +1432,9 @@ void ASTWriter::WriteControlBlock(Preprocessor &PP, ASTContext &Context,
   Record.push_back(static_cast<unsigned>(PPOpts.ObjCXXARCStandardLibrary));
   Stream.EmitRecord(PREPROCESSOR_OPTIONS, Record);
 
+  // Leave the options block.
+  Stream.ExitBlock();
+
   // Original file name and file ID
   SourceManager &SM = Context.getSourceManager();
   if (const FileEntry *MainFile = SM.getFileEntryForID(SM.getMainFileID())) {