From 1567da1e2820d4c1a6c14f4598ad3addba6bc788 Mon Sep 17 00:00:00 2001 From: Matt Turner Date: Mon, 22 Feb 2016 10:25:38 -0800 Subject: [PATCH] i965/fs: Don't CSE negated multiplies with saturation. It's not correct to CSE these multiplies mul.sat dst1, -a, b mul.sat dst2, a, b by emitting a negated MOV from dst1 to dst2: mul.sat dst1, -a, b mov dst2, -dst1 Take 2.0*2.0 for example. The first multiply would produce 0.0 and the second would produce 1.0. Fixes bad generated code in 18 to 22 shaders: instructions in affected programs: 432 -> 464 (7.41%) helped: 4 HURT: 18 Cc: mesa-stable@lists.freedesktop.org Reviewed-by: Ian Romanick --- src/mesa/drivers/dri/i965/brw_fs_cse.cpp | 2 ++ 1 file changed, 2 insertions(+) diff --git a/src/mesa/drivers/dri/i965/brw_fs_cse.cpp b/src/mesa/drivers/dri/i965/brw_fs_cse.cpp index cde6566c05c..0e743de7faf 100644 --- a/src/mesa/drivers/dri/i965/brw_fs_cse.cpp +++ b/src/mesa/drivers/dri/i965/brw_fs_cse.cpp @@ -139,6 +139,8 @@ operands_match(const fs_inst *a, const fs_inst *b, bool *negate) ys[1].f = ys1_imm; *negate = (xs0_negate != xs1_negate) != (ys0_negate != ys1_negate); + if (*negate && (a->saturate || b->saturate)) + return false; return ret; } else if (!a->is_commutative()) { bool match = true; -- 2.30.2