nir/algebraic: Mark some value range analysis-based optimizations imprecise

This didn't fix bug #111308, but it was found will trying to find the
actual cause of that bug.

Fixes piglit tests (new in piglit!110):

    - fs-fract-of-NaN.shader_test
    - fs-lt-nan-tautology.shader_test
    - fs-ge-nan-tautology.shader_test

No shader-db changes on any Intel platform.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111308
Fixes: b77070e293c ("nir/algebraic: Use value range analysis to eliminate tautological compares")
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>

diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index 6f0a439352416354c821fbea4178d7f22cb93805..3fc35995bcac1251dc882e7f184c215c258614bf 100644 (file)
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -807,7 +807,8 @@ optimizations.extend([
    (('ffloor', 'a(is_integral)'), a),
    (('fceil', 'a(is_integral)'), a),
    (('ftrunc', 'a(is_integral)'), a),
-   (('ffract', 'a(is_integral)'), 0.0),
+   # fract(x) = x - floor(x), so fract(NaN) = NaN
+   (('~ffract', 'a(is_integral)'), 0.0),
    (('fabs', 'a(is_not_negative)'), a),
    (('iabs', 'a(is_not_negative)'), a),
    (('fsat', 'a(is_not_positive)'), 0.0),
@@ -837,15 +838,18 @@ optimizations.extend([
    (('fne', 'a(is_not_zero)', 0.0), True),
    (('feq', 'a(is_not_zero)', 0.0), False),
 
-   (('fge', 'a(is_not_negative)', 'b(is_not_positive)'), True),
-   (('fge', 'b(is_not_positive)', 'a(is_gt_zero)'),      False),
-   (('fge', 'a(is_lt_zero)',      'b(is_not_negative)'), False),
-   (('fge', 'b(is_not_negative)', 'a(is_not_positive)'), True),
+   # The results expecting true, must be marked imprecise.  The results
+   # expecting false are fine because NaN compared >= or < anything is false.
 
-   (('flt', 'a(is_not_negative)', 'b(is_not_positive)'), False),
-   (('flt', 'b(is_not_positive)', 'a(is_gt_zero)'),      True),
-   (('flt', 'a(is_lt_zero)',      'b(is_not_negative)'), True),
-   (('flt', 'b(is_not_negative)', 'a(is_not_positive)'), False),
+   (('~fge', 'a(is_not_negative)', 'b(is_not_positive)'), True),
+   (('fge',  'b(is_not_positive)', 'a(is_gt_zero)'),      False),
+   (('fge',  'a(is_lt_zero)',      'b(is_not_negative)'), False),
+   (('~fge', 'b(is_not_negative)', 'a(is_not_positive)'), True),
+
+   (('flt',  'a(is_not_negative)', 'b(is_not_positive)'), False),
+   (('~flt', 'b(is_not_positive)', 'a(is_gt_zero)'),      True),
+   (('~flt', 'a(is_lt_zero)',      'b(is_not_negative)'), True),
+   (('flt',  'b(is_not_negative)', 'a(is_not_positive)'), False),
 
    (('ine', 'a(is_not_zero)', 0), True),
    (('ieq', 'a(is_not_zero)', 0), False),