[Mesa-dev] Step towards dropping more GLSL IR opts

[Timothy Arceri]

This is a collection of patches I've written and collected that
aim to reduce the pain when dropping brw_do_channel_expressions()
and brw_do_vector_splitting() two passes that combined take about
14% of the time it takes to run shader-db. This series includes
Ken's move comparisions series with a couple of small changes.

I have a few more changes that make good progress at removing 
regressions but they are all basically poor mans attempts at
tree height lowering and we would be much better off implementing
a proper pass to do this.

Jenkins is reporting that fbo-generatemipmap-formats is crashing
due to this series on g965/m64, ilk/m64, g45/m64 but I can't
reproduce that with INTEL_DEVID_OVERRIDE so I assume its telling
me lies.

Each opt patch has its own shader-db results.

Shader-db results for the whole series on BDW:

total instructions in shared programs: 13070792 -> 13044633 (-0.20%)
instructions in affected programs: 2718825 -> 2692666 (-0.96%)
helped: 8499
HURT: 269

total cycles in shared programs: 256597034 -> 256406494 (-0.07%)
cycles in affected programs: 168145092 -> 167954552 (-0.11%)
helped: 8794
HURT: 3706

total loops in shared programs: 2950 -> 2942 (-0.27%)
loops in affected programs: 8 -> 0
helped: 7
HURT: 0

total spills in shared programs: 15107 -> 14745 (-2.40%)
spills in affected programs: 9339 -> 8977 (-3.88%)
helped: 353
HURT: 0

total fills in shared programs: 20213 -> 19850 (-1.80%)
fills in affected programs: 12863 -> 12500 (-2.82%)
helped: 353
HURT: 0

LOST:   2
GAINED: 23