nir/algebraic: mark some optimizations with fsat(NaN) as inexact

[mesa.git] / src / compiler / nir / nir_opt_algebraic.py

diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index 2fe41d02deb12d357ea2045a1118f464741c254e..d775a23fceec574d8c56ac77095aca36894823e5 100644 (file)
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -329,10 +329,14 @@ optimizations.extend([
    (('fneu', ('fneg', a), -1.0), ('fneu', 1.0, a)),
    (('feq', -1.0, ('fneg', a)), ('feq', a, 1.0)),
 
-   (('flt', ('fsat(is_used_once)', a), '#b(is_gt_0_and_lt_1)'), ('flt', a, b)),
+   # flt(fsat(a), b > 0 && b < 1) is inexact if a is NaN (fsat(NaN) is 0)
+   # because it returns True while flt(a, b) always returns False.
+   (('~flt', ('fsat(is_used_once)', a), '#b(is_gt_0_and_lt_1)'), ('flt', a, b)),
    (('flt', '#b(is_gt_0_and_lt_1)', ('fsat(is_used_once)', a)), ('flt', b, a)),
    (('fge', ('fsat(is_used_once)', a), '#b(is_gt_0_and_lt_1)'), ('fge', a, b)),
-   (('fge', '#b(is_gt_0_and_lt_1)', ('fsat(is_used_once)', a)), ('fge', b, a)),
+   # fge(b > 0 && b < 1, fsat(a)) is inexact if a is NaN (fsat(NaN) is 0)
+   # because it returns True while fge(b, a) always returns False.
+   (('~fge', '#b(is_gt_0_and_lt_1)', ('fsat(is_used_once)', a)), ('fge', b, a)),
    (('feq', ('fsat(is_used_once)', a), '#b(is_gt_0_and_lt_1)'), ('feq', a, b)),
    (('fneu', ('fsat(is_used_once)', a), '#b(is_gt_0_and_lt_1)'), ('fneu', a, b)),
 
@@ -1913,7 +1917,9 @@ late_optimizations = [
    (('fneu', ('fsat(is_used_once)', a), '#b(is_gt_0_and_lt_1)'), ('fneu', a, b)),
 
    (('fge', ('fsat(is_used_once)', a), 1.0), ('fge', a, 1.0)),
-   (('flt', ('fsat(is_used_once)', a), 1.0), ('flt', a, 1.0)),
+   # flt(fsat(a), 1.0) is inexact because it returns True if a is NaN
+   # (fsat(NaN) is 0), while flt(a, 1.0) always returns FALSE.
+   (('~flt', ('fsat(is_used_once)', a), 1.0), ('flt', a, 1.0)),
 
    (('~fge', ('fmin(is_used_once)', ('fadd(is_used_once)', a, b), ('fadd', c, d)), 0.0), ('iand', ('fge', a, ('fneg', b)), ('fge', c, ('fneg', d)))),