[Mesa-dev] i965: FS copy propagation across control flow

[Eric Anholt]

Here's a patch series to clean up the most glaring failures I think we have
left in FS code generation other than variable-indexed array access.
Unfortunately, I haven't found a particular testcase to show that it's a
performance improvement, but I still think it's a good idea since it does
remove instructions.

I was hoping this series would let me remove the badly-named
register_coalesce() pass, but it turns out that doing so increases shader-db
instruction count by a significant fraction of a percent.  A bit of a
surprise.