[Mesa-dev] i965 global copy propagation fixes

[Kenneth Graunke]

Hello,

This surprisingly large series fixes bugs in the data flow algorithm
for copy propagation.  As far as I can tell, there were a myriad of
issues.  The updated algorithm seems to follow the textbook and
online materials much more closely.

No Piglit regressions on Ivybridge.

shader-db statistics are more or less a wash:

total instructions in shared programs: 1569184 -> 1569423 (0.02%)
instructions in affected programs:     44961 -> 45200 (0.53%)

A bunch of things are helped by a small margin, while other things are hurt
by a small margin (a couple of extra MOVs).  The few hurt shaders I looked
into appeared to suffer from compute-to-MRF not handling control flow.
There may be other reasons as well.

I'd still like to land it, though, as the old algorithm seems to be
pretty broken.


--Ken