Floating point SEL.CMOD may flush denorms to zero. We don't have enough
information at this point in compilation to know whether or not it is
safe to remove that.
Integer SEL or SEL without a conditional modifier is just a fancy
MOV. Those are always safe to eliminate.
See also 3f782cdd25.
Fixes: fab92fa1cb ("i965/fs: Optimize SEL with the same sources into a MOV.")
No shader-db changes on any Intel platform.
fossil-db:
All Intel platforms had similar results. (Lunar Lake shown)
Totals:
Instrs: 209903490 -> 209903492 (+0.00%)
Cycle count: 30546025224 -> 30546021980 (-0.00%); split: -0.00%, +0.00%
Max live registers: 65516231 -> 65516235 (+0.00%)
Totals from 2 (0.00% of 706657) affected shaders:
Instrs: 3197 -> 3199 (+0.06%)
Cycle count: 361650 -> 358406 (-0.90%); split: -10.05%, +9.15%
Max live registers: 300 -> 304 (+1.33%)
Reviewed-by: Ivan Briano <ivan.briano@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34192>
The condition modifier on SEL means something completely different than
it means on MOV. On MOV it means to modify the flags based on the value
written to the destination. On SEL it means to compare the sources using
that mode and pick the result (i.e., as min() or max()) without
modifying the flags.
The resulting MOV should not have a condition modifier for the same
reason it (already) doesn't have a predicate. This bug was found by
inspection, so I added a unit test.
No shader-db or shader-db changes on any Intel platform.
Fixes: fab92fa1cb ("i965/fs: Optimize SEL with the same sources into a MOV.")
Reviewed-by: Ivan Briano <ivan.briano@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34192>
