KonstantinSeurer
/
mesa
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

nir: Simplify fne(fneg(a), a) -> fne(a, 0.0) 

-NaN != NaN, and -Inf != Inf, so this should be safe.
Found while working on my VRP pass.

Shader-db results on my IVB:
total instructions in shared programs: 1698267 -> 1698067 (-0.01%)
instructions in affected programs:     15785 -> 15585 (-1.27%)
helped:                                36
HURT:                                  0
GAINED:                                0
LOST:                                  0

Some shaders was found to have the following pattern in NIR:
vec1 ssa_26 = fneg ssa_21
vec1 ssa_27 = fne ssa_21, ssa_26

Make that:
vec1 ssa_27 = fne ssa_21, 0.0f

This is found in Dota2 and Brutal Legend.
One shader is cut by 8%, from 323 -> 296 instructons in SIMD8

Signed-off-by: Thomas Helland <thomashelland90@gmail.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
This commit is contained in:
Thomas Helland 2015-08-06 13:36:04 +02:00 committed by Matt Turner
parent 29264d0d0c
commit a39167d594
1 changed files with 1 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
src/glsl/nir/nir_opt_algebraic.py
View File

@ -113,6 +113,7 @@ optimizations = [
(('sge', a, b), ('b2f', ('fge', a, b)), 'options->lower_scmp'),
(('seq', a, b), ('b2f', ('feq', a, b)), 'options->lower_scmp'),
(('sne', a, b), ('b2f', ('fne', a, b)), 'options->lower_scmp'),
(('fne', ('fneg', a), a), ('fne', a, 0.0)),
# Emulating booleans
(('imul', ('b2i', a), ('b2i', b)), ('b2i', ('iand', a, b))),
(('fmul', ('b2f', a), ('b2f', b)), ('b2f', ('iand', a, b))),