nir: Collapse repeated bcsels on the same argument.

vc4 results:
total instructions in shared programs: 39881 -> 39794 (-0.22%)
instructions in affected programs:     6302 -> 6215 (-1.38%)

Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

diff --git a/src/glsl/nir/nir_opt_algebraic.py b/src/glsl/nir/nir_opt_algebraic.py
index c3a884bb1e648adb38262c14f1f5152ef63a1d61..3ea6320d36c329075456a203bdb25cd4a2af742e 100644 (file)
--- a/src/glsl/nir/nir_opt_algebraic.py
+++ b/src/glsl/nir/nir_opt_algebraic.py
@@ -86,6 +86,7 @@ optimizations = [
    (('bcsel', ('flt', a, b), a, b), ('fmin', a, b)),
    (('bcsel', ('flt', a, b), b, a), ('fmax', a, b)),
    (('bcsel', ('inot', 'a@bool'), b, c), ('bcsel', a, c, b)),
+   (('bcsel', a, ('bcsel', a, b, c), d), ('bcsel', a, b, d)),
    (('fmin', ('fmax', a, 0.0), 1.0), ('fsat', a), '!options->lower_fsat'),
    (('fsat', a), ('fmin', ('fmax', a, 0.0), 1.0), 'options->lower_fsat'),
    (('fsat', ('fsat', a)), ('fsat', a)),