Improve coordination between the module manager and the global module

index, optimizing the operation that skips lookup in modules where we
know the identifier will not be found. This makes the global module
index optimization actually useful, providing an 8.5% speedup over
modules without the global module index for -fsyntax-only.

llvm-svn: 173529

1 files changed, 5 insertions, 26 deletions

diff --git a/clang/lib/Serialization/GlobalModuleIndex.cpp b/clang/lib/Serialization/GlobalModuleIndex.cpp
index b1923982803..b778a72ba2e 100644
--- a/clang/lib/Serialization/GlobalModuleIndex.cpp
+++ b/clang/lib/Serialization/GlobalModuleIndex.cpp
@@ -127,7 +127,8 @@ struct LoadedModuleInfo {
 GlobalModuleIndex::GlobalModuleIndex(FileManager &FileMgr,
                                      llvm::MemoryBuffer *Buffer,
                                      llvm::BitstreamCursor Cursor)
-  : Buffer(Buffer), IdentifierIndex()
+  : Buffer(Buffer), IdentifierIndex(),
+    NumIdentifierLookups(), NumIdentifierLookupHits()
 {
   typedef llvm::DenseMap<unsigned, LoadedModuleInfo> LoadedModulesMap;
   LoadedModulesMap LoadedModules;
@@ -368,10 +369,8 @@ void GlobalModuleIndex::getModuleDependencies(
   Dependencies = Modules[Known->second].Dependencies;
 }
 
-bool GlobalModuleIndex::lookupIdentifier(
-       StringRef Name,
-       SmallVectorImpl<const FileEntry *> &ModuleFiles) {
-  ModuleFiles.clear();
+bool GlobalModuleIndex::lookupIdentifier(StringRef Name, HitSet &Hits) {
+  Hits.clear();
   
   // If there's no identifier index, there is nothing we can do.
   if (!IdentifierIndex)
@@ -392,29 +391,13 @@ bool GlobalModuleIndex::lookupIdentifier(
     if (ID >= Modules.size() || !Modules[ID].File)
       continue;
 
-    ModuleFiles.push_back(Modules[ID].File);
+    Hits.insert(Modules[ID].File);
   }
 
   ++NumIdentifierLookupHits;
   return true;
 }
 
-GlobalModuleIndex::SkipSet
-GlobalModuleIndex::computeSkipSet(
-  const SmallVectorImpl<const FileEntry *> &ModuleFiles) {
-  llvm::SmallPtrSet<const FileEntry *, 8> Found(ModuleFiles.begin(),
-                                                ModuleFiles.end());
-
-  SkipSet Result;
-  for (unsigned I = 0, N = Modules.size(); I != N; ++I) {
-    if (Modules[I].File && !Found.count(Modules[I].File))
-      Result.insert(Modules[I].File);
-  }
-
-  NumIdentifierModulesSkipped += Result.size();
-  return Result;
-}
-
 void GlobalModuleIndex::printStats() {
   std::fprintf(stderr, "*** Global Module Index Statistics:\n");
   if (NumIdentifierLookups) {
@@ -422,10 +405,6 @@ void GlobalModuleIndex::printStats() {
             NumIdentifierLookupHits, NumIdentifierLookups,
             (double)NumIdentifierLookupHits*100.0/NumIdentifierLookups);
   }
-  if (NumIdentifierLookups && NumIdentifierModulesSkipped) {
-    fprintf(stderr, "  %f modules skipped per lookup (on average)\n",
-            (double)NumIdentifierModulesSkipped/NumIdentifierLookups);
-  }
   std::fprintf(stderr, "\n");
 }