[Mesa-dev] [PATCH 4/9] nir: Move the compare-with-zero optimizations to the late section

[Jason Ekstrand]

total instructions in shared programs: 4422307 -> 4422363 (0.00%)
instructions in affected programs:     4230 -> 4286 (1.32%)
helped:                                0
HURT:                                  12

While this does hurt some things, the losses are minor and it prevents the
compare-with-zero optimization from fighting with ffma which is much more
important.
---
 src/glsl/nir/nir_opt_algebraic.py | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/src/glsl/nir/nir_opt_algebraic.py b/src/glsl/nir/nir_opt_algebraic.py
index 84d4c72..cfb1429 100644
--- a/src/glsl/nir/nir_opt_algebraic.py
+++ b/src/glsl/nir/nir_opt_algebraic.py
@@ -82,10 +82,6 @@ optimizations = [
    (('inot', ('fge', a, b)), ('flt', a, b)),
    (('inot', ('ilt', a, b)), ('ige', a, b)),
    (('inot', ('ige', a, b)), ('ilt', a, b)),
-   (('flt', ('fadd', a, b), 0.0), ('flt', a, ('fneg', b))),
-   (('fge', ('fadd', a, b), 0.0), ('fge', a, ('fneg', b))),
-   (('feq', ('fadd', a, b), 0.0), ('feq', a, ('fneg', b))),
-   (('fne', ('fadd', a, b), 0.0), ('fne', a, ('fneg', b))),
    (('fge', ('fneg', ('fabs', a)), 0.0), ('feq', a, 0.0)),
    (('bcsel', ('flt', a, b), a, b), ('fmin', a, b)),
    (('bcsel', ('flt', a, b), b, a), ('fmax', a, b)),
@@ -163,9 +159,6 @@ optimizations = [
    (('iadd', a, ('isub', 0, b)), ('isub', a, b)),
    (('fabs', ('fsub', 0.0, a)), ('fabs', a)),
    (('iabs', ('isub', 0, a)), ('iabs', a)),
-
-# This one may not be exact
-   (('feq', ('fadd', a, b), 0.0), ('feq', a, ('fneg', b))),
 ]
 
 # Add optimizations to handle the case where the result of a ternary is
@@ -194,6 +187,10 @@ for op in ['flt', 'fge', 'feq', 'fne',
 # they help code generation but do not necessarily produce code that is
 # more easily optimizable.
 late_optimizations = [
+   (('flt', ('fadd', a, b), 0.0), ('flt', a, ('fneg', b))),
+   (('fge', ('fadd', a, b), 0.0), ('fge', a, ('fneg', b))),
+   (('feq', ('fadd', a, b), 0.0), ('feq', a, ('fneg', b))),
+   (('fne', ('fadd', a, b), 0.0), ('fne', a, ('fneg', b))),
 ]
 
 print nir_algebraic.AlgebraicPass("nir_opt_algebraic", optimizations).render()
-- 
2.3.3