Mesa (master): intel/vec4: Allow late copy propagation on vec4
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Wed Apr 1 00:48:44 UTC 2020
Module: Mesa
Branch: master
Commit: d2b4f3f1374c179e066b1fec56875613b7e64945
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=d2b4f3f1374c179e066b1fec56875613b7e64945
Author: Ian Romanick <ian.d.romanick at intel.com>
Date: Mon Jun 10 16:45:08 2019 -0700
intel/vec4: Allow late copy propagation on vec4
This change incurs a small amount of hurt now, but it enables a lot of
benefit on vec4 shaders on the next commit. nir_opt_algebraic_late
converts dph, dot3, etc. to dhp_replicated, dot_replicated3, etc. In
the process, it introduces extra moves. If the original NIR contained
vec1 32 ssa_45 = fdot4 ssa_51, ssa_44
vec1 32 ssa_46 = fneg ssa_45
nir_opt_algebraic_late will produce
vec4 32 ssa_18 = fdot_replicated4 ssa_1, ssa_15
vec1 32 ssa_19 = mov ssa_18.x
vec1 32 ssa_17 = fneg ssa_19
The algebraic pass added in the next commit can't see through the move
to know that the fneg applies to a fdot_replicated4.
Haswell, Ivy Bridge, and Sandybridge had similar results. (Haswell shown)
total cycles in shared programs: 187077604 -> 187079858 (<.01%)
cycles in affected programs: 350132 -> 352386 (0.64%)
helped: 174
HURT: 194
helped stats (abs) min: 2 max: 124 x̄: 23.60 x̃: 16
helped stats (rel) min: 0.12% max: 15.88% x̄: 4.98% x̃: 3.86%
HURT stats (abs) min: 2 max: 164 x̄: 32.78 x̃: 16
HURT stats (rel) min: 0.17% max: 22.82% x̄: 6.46% x̃: 0.86%
95% mean confidence interval for cycles value: 2.04 10.21
95% mean confidence interval for cycles %-change: 0.17% 1.93%
Cycles are HURT.
No shader-db changes on any other Intel platform.
Reviewed-by: Matt Turner <mattst88 at gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/1359>
---
src/intel/compiler/brw_nir.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/src/intel/compiler/brw_nir.c b/src/intel/compiler/brw_nir.c
index 25395747c13..8c0be0d8a26 100644
--- a/src/intel/compiler/brw_nir.c
+++ b/src/intel/compiler/brw_nir.c
@@ -907,10 +907,10 @@ brw_postprocess_nir(nir_shader *nir, const struct brw_compiler *compiler,
* havok on the vec4 backend. The handling of constants in the vec4
* backend is not good.
*/
- if (is_scalar) {
+ if (is_scalar)
OPT(nir_opt_constant_folding);
- OPT(nir_copy_prop);
- }
+
+ OPT(nir_copy_prop);
OPT(nir_opt_dce);
OPT(nir_opt_cse);
}
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