Add a cache to SourceManager to accellerate line # lookup. This is a

bottleneck for -E computation, because every token that starts a line needs
to determine *which* line it is on (so -E mode can insert the appropriate 
vertical whitespace).  This optimization improves this common case where
it is striding through the line # table.

This speeds up -E on xalancbmk by 3.2%


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@40459 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 1 deletions

diff --git a/include/clang/Basic/SourceManager.h b/include/clang/Basic/SourceManager.h
index f06a6fbf54..dd8a86cc7e 100644
--- a/include/clang/Basic/SourceManager.h
+++ b/include/clang/Basic/SourceManager.h
@@ -154,13 +154,21 @@ class SourceManager {
   /// MacroIDs - Information about each MacroID.
   std::vector<SrcMgr::MacroIDInfo> MacroIDs;
   
+  /// LastLineNo - These ivars serve as a cache used in the getLineNumber
+  /// method which is used to speedup getLineNumber calls to nearby locations.
+  unsigned LastLineNoFileIDQuery;
+  SrcMgr::FileInfo *LastLineNoFileInfo;
+  unsigned LastLineNoFilePos;
+  unsigned LastLineNoResult;
 public:
-  SourceManager() {}
+  SourceManager() : LastLineNoFileIDQuery(~0U) {}
   ~SourceManager();
   
   void clearIDTables() {
     FileIDs.clear();
     MacroIDs.clear();
+    LastLineNoFileIDQuery = ~0U;
+    LastLineNoFileInfo = 0;
   }
   
   /// createFileID - Create a new FileID that represents the specified file