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nir/algebraic: Recognize open-coded bitfield_reverse in XCOM 2

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The XCOM 2 shaders in my shader-db use iadd instead of ior.

No fossil-db changes on any Intel platform.

shader-db:

All Intel platforms had similar results. (Meteor Lake shown)
total instructions in shared programs: 19787210 -> 19787034 (<.01%)
instructions in affected programs: 1187 -> 1011 (-14.83%)
helped: 6 / HURT: 0

total cycles in shared programs: 906024436 -> 906012612 (<.01%)
cycles in affected programs: 72978 -> 61154 (-16.20%)
helped: 6 / HURT: 0

Reviewed-by: Georg Lehmann <dadschoorse@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31006>
This commit is contained in:
Ian Romanick 2024-09-04 14:16:12 -07:00 • committed by Marge Bot
parent 97f4250a7c
commit 057c7c9f53
1 changed files with 11 additions and 0 deletions
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11
src/compiler/nir/nir_opt_algebraic.py
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@ -2759,6 +2759,16 @@ optimizations += [
(('ldexp@64', 'x', 'exp'), ldexp('x', 'exp', 64), 'options->lower_ldexp'),
]
# XCOM 2 (OpenGL) open-codes bitfieldReverse()
def bitfield_reverse_xcom2(u):
step1 = ('iadd', ('ishl', u, 16), ('ushr', u, 16))
step2 = ('iadd', ('iand', ('ishl', step1, 1), 0xaaaaaaaa), ('iand', ('ushr', step1, 1), 0x55555555))
step3 = ('iadd', ('iand', ('ishl', step2, 2), 0xcccccccc), ('iand', ('ushr', step2, 2), 0x33333333))
step4 = ('iadd', ('iand', ('ishl', step3, 4), 0xf0f0f0f0), ('iand', ('ushr', step3, 4), 0x0f0f0f0f))
step5 = ('iadd(many-comm-expr)', ('iand', ('ishl', step4, 8), 0xff00ff00), ('iand', ('ushr', step4, 8), 0x00ff00ff))
return step5
# Unreal Engine 4 demo applications open-codes bitfieldReverse()
def bitfield_reverse_ue4(u):
step1 = ('ior', ('ishl', u, 16), ('ushr', u, 16))
@ -2779,6 +2789,7 @@ def bitfield_reverse_cp2077(u):
return step5
optimizations += [(bitfield_reverse_xcom2('x@32'), ('bitfield_reverse', 'x'), '!options->lower_bitfield_reverse')]
optimizations += [(bitfield_reverse_ue4('x@32'), ('bitfield_reverse', 'x'), '!options->lower_bitfield_reverse')]
optimizations += [(bitfield_reverse_cp2077('x@32'), ('bitfield_reverse', 'x'), '!options->lower_bitfield_reverse')]