From 8e7728077435c5c5ad8c328761277f8ff3b32112 Mon Sep 17 00:00:00 2001 From: Samuel Pitoiset Date: Tue, 4 Feb 2020 17:25:35 +0100 Subject: [PATCH] nir: do not use De Morgan's Law rules for flt and fge In presence of NaNs, "!(flt(a, b) && flt(c, d))" is NOT EQUAL to "fge(a, b) || fge(c, d)". These optimizations are unsafe for apps that rely on NaN behaviour. pipeline-db (GFX9/LLVM): Totals from affected shaders: SGPRS: 3176 -> 3136 (-1.26 %) VGPRS: 2188 -> 2144 (-2.01 %) Spilled SGPRs: 227 -> 169 (-25.55 %) Code Size: 150572 -> 151800 (0.82 %) bytes Max Waves: 307 -> 310 (0.98 %) pipeline-db (GFX9/ACO): Totals from affected shaders: SGPRS: 18744 -> 18744 (0.00 %) VGPRS: 15576 -> 15580 (0.03 %) Spilled SGPRs: 164 -> 164 (0.00 %) Code Size: 1573012 -> 1576492 (0.22 %) bytes Max Waves: 1534 -> 1532 (-0.13 %) Closes: https://gitlab.freedesktop.org/mesa/mesa/issues/2127 Fixes: d1ed4ffe0b7 ("nir: Use De Morgan's Law on logic compounded comparisons") Signed-off-by: Samuel Pitoiset Reviewed-by: Ian Romanick Tested-by: Marge Bot Part-of: --- src/compiler/nir/nir_opt_algebraic.py | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py index f9fc119505f..904b02e0309 100644 --- a/src/compiler/nir/nir_opt_algebraic.py +++ b/src/compiler/nir/nir_opt_algebraic.py @@ -1279,7 +1279,7 @@ for bit_size in [8, 16, 32, 64]: ('bcsel', ('ilt', a, ('isub', a, b)), intmin, ('isub', a, b))), 'options->lower_add_sat'), ] -invert = OrderedDict([('feq', 'fne'), ('fne', 'feq'), ('fge', 'flt'), ('flt', 'fge')]) +invert = OrderedDict([('feq', 'fne'), ('fne', 'feq')]) for left, right in itertools.combinations_with_replacement(invert.keys(), 2): optimizations.append((('inot', ('ior(is_used_once)', (left, a, b), (right, c, d))), -- 2.30.2