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-sta...@lists.freedesktop.org
---
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 cde6566..0e743de 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;
--
2.4.10
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/mesa-dev
