Add a new RewriteRope data structure which is a smarter way to represent the text

backing a rewrite buffer than using an std::vector<char>.  This class was hacked
together very quickly and needs to be cleaned up, but it seems to work.  It speeds
up rewriting a a 7M file from 6.43s to 0.24s on my machine.  The impl could also
be made to be a lot more algorithmically sound.

This produces identical output to using vector on this testcase, if it causes a
problems or bugs are encountered, it can be disabled by changing the 
RewriteBuffer::Buffer typedef back.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@43884 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 0 deletions

diff --git a/Rewrite/Rewriter.cpp b/Rewrite/Rewriter.cpp
index 1df169ac84..3a007f3e71 100644
--- a/Rewrite/Rewriter.cpp
+++ b/Rewrite/Rewriter.cpp
@@ -120,6 +120,11 @@ void RewriteBuffer::ReplaceText(unsigned OrigOffset, unsigned OrigLength,
   unsigned RealOffset = getMappedOffset(OrigOffset, true);
   assert(RealOffset+OrigLength <= Buffer.size() && "Invalid location");
 
+  Buffer.erase(Buffer.begin()+RealOffset, Buffer.begin()+RealOffset+OrigLength);
+  Buffer.insert(Buffer.begin()+RealOffset, NewStr, NewStr+NewLength);
+  AddDelta(OrigOffset, NewLength-OrigLength);
+  return;
+  
   // Overwrite the common piece.
   unsigned CommonLength = std::min(OrigLength, NewLength);
   std::copy(NewStr, NewStr+CommonLength, Buffer.begin()+RealOffset);