Implement the writer side of the global module index.

The global module index is a "global" index for all of the module
files within a particular subdirectory in the module cache, which
keeps track of all of the "interesting" identifiers and selectors
known in each of the module files. One can perform a fast lookup in
the index to determine which module files will have more information
about entities with a particular name/selector. This information can
help eliminate redundant lookups into module files (a serious
performance problem) and help with creating auto-import/auto-include
Fix-Its.

The global module index is created or updated at the end of a
translation unit that has triggered a (re)build of a module by
scraping all of the .pcm files out of the module cache subdirectory,
so it catches everything. As with module rebuilds, we use the file
system's atomicity to synchronize.

llvm-svn: 173301

1 files changed, 11 insertions, 0 deletions

diff --git a/clang/lib/Frontend/FrontendAction.cpp b/clang/lib/Frontend/FrontendAction.cpp
index 742caf158ba..4b642b395cb 100644
--- a/clang/lib/Frontend/FrontendAction.cpp
+++ b/clang/lib/Frontend/FrontendAction.cpp
@@ -23,6 +23,7 @@
 #include "clang/Parse/ParseAST.h"
 #include "clang/Serialization/ASTDeserializationListener.h"
 #include "clang/Serialization/ASTReader.h"
+#include "clang/Serialization/GlobalModuleIndex.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MemoryBuffer.h"
@@ -380,6 +381,16 @@ bool FrontendAction::Execute() {
   }
   else ExecuteAction();
 
+  // If we are supposed to rebuild the global module index, do so now unless
+  // an error occurred.
+  if (CI.getBuildGlobalModuleIndex() && CI.hasFileManager() &&
+      CI.hasPreprocessor() &&
+      (!CI.hasDiagnostics() || !CI.getDiagnostics().hasErrorOccurred())) {
+    GlobalModuleIndex::writeIndex(
+      CI.getFileManager(),
+      CI.getPreprocessor().getHeaderSearchInfo().getModuleCachePath());
+  }
+
   return true;
 }