On 23/1/19 7:17 am, Caio Marcelo de Oliveira Filho wrote:
Hi,
I like this patch, did it get dropped for a specific reason or just
forgotten?
Did you look at any of the HURT? The problem I was seeing was this could
end up stopping copy propagation from working on some UBOs etc.
For example if you have something like:
load UBO at offset offset_a;
if (offset_a == 10) {
load UBO at offset offset_a;
...
}
Without this patch this will get optimised to a single UBO load outside
the loop.
However with this patch we end up with:
load UBO at offset offset_a;
if (offset_a == 10) {
load UBO at offset 10;
...
}
copy prop no longer recognizes that we are reusing the same UBO and
reloads it again.
shader-db results skl:
total instructions in shared programs: 15049273 -> 15049211 (<.01%)
instructions in affected programs: 75678 -> 75616 (-0.08%)
helped: 197
HURT: 8
total cycles in shared programs: 369994915 -> 370136090 (0.04%)
cycles in affected programs: 1750477 -> 1891652 (8.06%)
helped: 91
HURT: 91
total loops in shared programs: 4401 -> 4401 (0.00%)
loops in affected programs: 0 -> 0
helped: 0
HURT: 0
total spills in shared programs: 10159 -> 10159 (0.00%)
spills in affected programs: 0 -> 0
helped: 0
HURT: 0
total fills in shared programs: 22118 -> 22118 (0.00%)
fills in affected programs: 0 -> 0
helped: 0
HURT: 0
LOST: 0
GAINED: 0
+static bool
+opt_for_known_values(nir_builder *b, nir_if *nif)
+{
+ bool progress = false;
Remove because unused.
+ nir_ssa_def *src0 = alu->src[0].src.ssa;
+ nir_ssa_def *src1 = alu->src[1].src.ssa;
+ if (src0a->parent_instr->type == nir_instr_type_load_const) {
You fixed this already.
+
+ break;
+ }
+
+ default:
+ return false;
+ }
+
+ return false;
Optional: unless you plan to add more cases here, consider replacing
the switch with an if (alu->op == ... || alu->op == ...), so you don't
have this noise at the end.
With the 'progress' and the 'src0a' fixes, this patch is
Reviewed-by: Caio Marcelo de Oliveira Filho <[email protected]>
Caio
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