Optimize ModuleManager::visit() by precomputing the visitation order

and limiting ourselves to two memory allocations. 10% speedup in
-fsyntax-only time for modules.

With this change, we can actually see some performance different from
the global module index, but it's still about 1%.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@173512 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 1 deletions

diff --git a/include/clang/Serialization/ModuleManager.h b/include/clang/Serialization/ModuleManager.h
index 512d7e9b66..465da76787 100644
--- a/include/clang/Serialization/ModuleManager.h
+++ b/include/clang/Serialization/ModuleManager.h
@@ -38,7 +38,10 @@ class ModuleManager {
   
   /// \brief A lookup of in-memory (virtual file) buffers
   llvm::DenseMap<const FileEntry *, llvm::MemoryBuffer *> InMemoryBuffers;
-  
+
+  /// \brief The visitation order.
+  SmallVector<ModuleFile *, 4> VisitOrder;
+
 public:
   typedef SmallVector<ModuleFile*, 2>::iterator ModuleIterator;
   typedef SmallVector<ModuleFile*, 2>::const_iterator ModuleConstIterator;