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nir/algebraic: optimize Cyberpunk 2077's open-coded bitfieldReverse()

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fossil-db (Sienna Cichlid):
Totals from 9 (0.01% of 128647) affected shaders:
CodeSize: 29900 -> 28640 (-4.21%)
Instrs: 5677 -> 5443 (-4.12%)
Latency: 96561 -> 95025 (-1.59%)
Copies: 571 -> 544 (-4.73%)

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13673>
This commit is contained in:
Rhys Perry 2021-11-04 10:32:13 +00:00 • committed by Marge Bot
parent 9b8bc712b2
commit 12294026d5
1 changed files with 13 additions and 2 deletions
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15
src/compiler/nir/nir_opt_algebraic.py
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@ -2195,7 +2195,7 @@ optimizations += [
]
# Unreal Engine 4 demo applications open-codes bitfieldReverse()
def bitfield_reverse(u):
def bitfield_reverse_ue4(u):
step1 = ('ior', ('ishl', u, 16), ('ushr', u, 16))
step2 = ('ior', ('ishl', ('iand', step1, 0x00ff00ff), 8), ('ushr', ('iand', step1, 0xff00ff00), 8))
step3 = ('ior', ('ishl', ('iand', step2, 0x0f0f0f0f), 4), ('ushr', ('iand', step2, 0xf0f0f0f0), 4))
@ -2204,7 +2204,18 @@ def bitfield_reverse(u):
return step5
optimizations += [(bitfield_reverse('x@32'), ('bitfield_reverse', 'x'), '!options->lower_bitfield_reverse')]
# Cyberpunk 2077 open-codes bitfieldReverse()
def bitfield_reverse_cp2077(u):
step1 = ('ior', ('ishl', u, 16), ('ushr', u, 16))
step2 = ('ior', ('iand', ('ishl', step1, 1), 0xaaaaaaaa), ('iand', ('ushr', step1, 1), 0x55555555))
step3 = ('ior', ('iand', ('ishl', step2, 2), 0xcccccccc), ('iand', ('ushr', step2, 2), 0x33333333))
step4 = ('ior', ('iand', ('ishl', step3, 4), 0xf0f0f0f0), ('iand', ('ushr', step3, 4), 0x0f0f0f0f))
step5 = ('ior(many-comm-expr)', ('iand', ('ishl', step4, 8), 0xff00ff00), ('iand', ('ushr', step4, 8), 0x00ff00ff))
return step5
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')]
# "all_equal(eq(a, b), vec(~0))" is the same as "all_equal(a, b)"
# "any_nequal(neq(a, b), vec(0))" is the same as "any_nequal(a, b)"