It contains various optimization improvements:
- Handling of flow control instructions in dataflow analysis.
- More aggressive use of presubtact operations.
- Some scheduler improvements.
I'm seeing about a 10% decrease in shader program size in most piglit tests with this branch, but I haven't done much testing with real applications. I added a debug option a few weeks ago for dumping shader stats (RADEON_DEBUG=pstat), which I've been using with piglit and is helpful for comparing compiler performance between different branches.