Mesa (master): nir: Mark bcsel-to-fmin (or fmax) transformations as inexact
Ian Romanick
idr at kemper.freedesktop.org
Tue Mar 6 19:18:44 UTC 2018
Module: Mesa
Branch: master
Commit: 380136e998f8d89380adba7d071249d6469339db
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=380136e998f8d89380adba7d071249d6469339db
Author: Ian Romanick <ian.d.romanick at intel.com>
Date: Mon Feb 26 14:49:47 2018 -0800
nir: Mark bcsel-to-fmin (or fmax) transformations as inexact
These transformations are inexact because section 4.7.1 (Range and
Precision) says:
Operations and built-in functions that operate on a NaN are not
required to return a NaN as the result.
The fmin or fmax might not return NaN in cases where the original
expression would be required to return NaN.
Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>
---
src/compiler/nir/nir_opt_algebraic.py | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index ef240ae0e9..43b2948431 100644
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -168,8 +168,8 @@ optimizations = [
(('flt(is_not_used_by_conditional)', ('fadd(is_used_once)', a, ('fneg', b)), 0.0), ('flt', a, b)),
(('fge', ('fneg', ('fabs', a)), 0.0), ('feq', a, 0.0)),
- (('bcsel', ('flt', b, a), b, a), ('fmin', a, b)),
- (('bcsel', ('flt', a, b), b, a), ('fmax', a, b)),
+ (('~bcsel', ('flt', b, a), b, a), ('fmin', a, b)),
+ (('~bcsel', ('flt', a, b), b, a), ('fmax', a, b)),
(('~bcsel', ('fge', a, b), b, a), ('fmin', a, b)),
(('~bcsel', ('fge', b, a), b, a), ('fmax', a, b)),
(('bcsel', ('inot', a), b, c), ('bcsel', a, c, b)),
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