nir/algebraic: optimize bcsel(a, 0, 1) to b2i

This avoids combination with other bcsel operations,
and as b2i is often a no-op (when used for iadd and such),
the resulting pattern is preferable.

Totals from affected shaders: (VEGA)
SGPRS: 598448 -> 598448 (0.00 %)
VGPRS: 457940 -> 457352 (-0.13 %)
Spilled SGPRs: 127154 -> 127154 (0.00 %)
Spilled VGPRs: 0 -> 0 (0.00 %)
Private memory VGPRs: 0 -> 0 (0.00 %)
Scratch size: 0 -> 0 (0.00 %) dwords per thread
Code Size: 64836352 -> 64802728 (-0.05 %) bytes
LDS: 781 -> 781 (0.00 %) blocks
Max Waves: 22931 -> 22931 (0.00 %)

Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4830>

diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index 4b5fc5ecc9abd8c8668ed29e7f5c4e29e99ed0f3..507a4d397b7b8c89852aec2b3f93065bb05d2216 100644 (file)
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -859,6 +859,8 @@ optimizations.extend([
    # D3D Boolean emulation
    (('bcsel', a, -1, 0), ('ineg', ('b2i', 'a@1'))),
    (('bcsel', a, 0, -1), ('ineg', ('b2i', ('inot', a)))),
+   (('bcsel', a, 1, 0), ('b2i', 'a@1')),
+   (('bcsel', a, 0, 1), ('b2i', ('inot', a))),
    (('iand', ('ineg', ('b2i', 'a@1')), ('ineg', ('b2i', 'b@1'))),
     ('ineg', ('b2i', ('iand', a, b)))),
    (('ior', ('ineg', ('b2i','a@1')), ('ineg', ('b2i', 'b@1'))),