<rdar://problem/13479539> Simplify ModuleManager/GlobalModuleIndex interaction to eliminate a pile of extraneous stats().

The refactoring in r177367 introduced a serious performance bug where
the "lazy" resolution of module file names in the global module index
to actual module file entries in the module manager would perform
repeated negative stats(). The new interaction requires the module
manager to inform the global module index when a module file has been
loaded, eliminating the extraneous stat()s and a bunch of bookkeeping
on both sides.

llvm-svn: 177750

1 files changed, 18 insertions, 47 deletions

diff --git a/clang/lib/Serialization/ModuleManager.cpp b/clang/lib/Serialization/ModuleManager.cpp
index 7384da54043..193a38b9738 100644
--- a/clang/lib/Serialization/ModuleManager.cpp
+++ b/clang/lib/Serialization/ModuleManager.cpp
@@ -166,17 +166,6 @@ void ModuleManager::addInMemoryBuffer(StringRef FileName,
   InMemoryBuffers[Entry] = Buffer;
 }
 
-void ModuleManager::updateModulesInCommonWithGlobalIndex() {
-  ModulesInCommonWithGlobalIndex.clear();
-
-  if (!GlobalIndex)
-    return;
-
-  // Collect the set of modules known to the global index.
-  GlobalIndex->noteAdditionalModulesLoaded();
-  GlobalIndex->getKnownModules(ModulesInCommonWithGlobalIndex);
-}
-
 ModuleManager::VisitState *ModuleManager::allocateVisitState() {
   // Fast path: if we have a cached state, use it.
   if (FirstVisitState) {
@@ -198,10 +187,25 @@ void ModuleManager::returnVisitState(VisitState *State) {
 
 void ModuleManager::setGlobalIndex(GlobalModuleIndex *Index) {
   GlobalIndex = Index;
-  if (GlobalIndex) {
-    GlobalIndex->setResolver(this);
+  if (!GlobalIndex) {
+    ModulesInCommonWithGlobalIndex.clear();
+    return;
   }
-  updateModulesInCommonWithGlobalIndex();
+
+  // Notify the global module index about all of the modules we've already
+  // loaded.
+  for (unsigned I = 0, N = Chain.size(); I != N; ++I) {
+    if (!GlobalIndex->loadedModuleFile(Chain[I])) {
+      ModulesInCommonWithGlobalIndex.push_back(Chain[I]);
+    }
+  }
+}
+
+void ModuleManager::moduleFileAccepted(ModuleFile *MF) {
+  if (!GlobalIndex || GlobalIndex->loadedModuleFile(MF))
+    return;
+
+  ModulesInCommonWithGlobalIndex.push_back(MF);
 }
 
 ModuleManager::ModuleManager(FileManager &FileMgr)
@@ -264,11 +268,6 @@ ModuleManager::visit(bool (*Visitor)(ModuleFile &M, void *UserData),
 
     assert(VisitOrder.size() == N && "Visitation order is wrong?");
 
-    // We may need to update the set of modules we have in common with the
-    // global module index, since modules could have been added to the module
-    // manager since we loaded the global module index.
-    updateModulesInCommonWithGlobalIndex();
-
     delete FirstVisitState;
     FirstVisitState = 0;
   }
@@ -387,34 +386,6 @@ bool ModuleManager::lookupModuleFile(StringRef FileName,
   return false;
 }
 
-bool ModuleManager::resolveModuleFileName(StringRef FileName,
-                                          off_t ExpectedSize,
-                                          time_t ExpectedModTime,
-                                          ModuleFile *&File) {
-  File = 0;
-  
-  // Look for the file entry corresponding to this name.
-  const FileEntry *F;
-  if (lookupModuleFile(FileName, ExpectedSize, ExpectedModTime, F))
-    return true;
-
-  // If there is no file, we've succeeded (trivially).
-  if (!F)
-    return false;
-
-  // Determine whether we have a module file associated with this file entry.
-  llvm::DenseMap<const FileEntry *, ModuleFile *>::iterator Known
-    = Modules.find(F);
-  if (Known == Modules.end()) {
-    // We don't know about this module file; invalidate the cache.
-    FileMgr.invalidateCache(F);
-    return false;
-  }
-
-  File = Known->second;
-  return false;
-}
-
 #ifndef NDEBUG
 namespace llvm {
   template<>