[cfe-commits] r166265 - /cfe/trunk/lib/Basic/SourceManager.cpp

[Craig Topper]

Author: ctopper
Date: Thu Oct 18 23:40:38 2012
New Revision: 166265

URL: http://llvm.org/viewvc/llvm-project?rev=166265&view=rev
Log:
Teach getColumnNumber to use the line cache to get the start of the line if its on the same line as the last call to getLineNumber. Prevents needing to scan backwards for the new line. Fixes PR14106.

Modified:
    cfe/trunk/lib/Basic/SourceManager.cpp

Modified: cfe/trunk/lib/Basic/SourceManager.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Basic/SourceManager.cpp?rev=166265&r1=166264&r2=166265&view=diff
==============================================================================
--- cfe/trunk/lib/Basic/SourceManager.cpp (original)
+++ cfe/trunk/lib/Basic/SourceManager.cpp Thu Oct 18 23:40:38 2012
@@ -1029,6 +1029,17 @@
     return 1;
   }
 
+  // See if we just calculated the line number for this FilePos and can use
+  // that to lookup the start of the line instead of searching for it.
+  if (LastLineNoFileIDQuery == FID &&
+      LastLineNoContentCache->SourceLineCache != 0) {
+    unsigned *SourceLineCache = LastLineNoContentCache->SourceLineCache;
+    unsigned LineStart = SourceLineCache[LastLineNoResult - 1];
+    unsigned LineEnd = SourceLineCache[LastLineNoResult];
+    if (FilePos >= LineStart && FilePos < LineEnd)
+      return FilePos - LineStart + 1;
+  }
+
   const char *Buf = MemBuf->getBufferStart();
   unsigned LineStart = FilePos;
   while (LineStart && Buf[LineStart-1] != '\n' && Buf[LineStart-1] != '\r')