Mesa (master): i965: Enable vector shrinking in the vec4 backend.

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Module: Mesa
Branch: master
Commit: 023e6669cc1d7d321e0bd5b5293422cd73b3d658
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=023e6669cc1d7d321e0bd5b5293422cd73b3d658

Author: Eric Anholt <eric at anholt.net>
Date:   Wed Jul 22 21:35:07 2020 -0700

i965: Enable vector shrinking in the vec4 backend.

This manages to make some extra vec operations that would turn into movs
go away.

brw shader-db:
total instructions in shared programs: 3895037 -> 3893221 (-0.05%)
total cycles in shared programs: 113832759 -> 113792154 (-0.04%)

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6050>

---

 src/intel/compiler/brw_nir.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/intel/compiler/brw_nir.c b/src/intel/compiler/brw_nir.c
index 9a6914f92f2..510ab0b769c 100644
--- a/src/intel/compiler/brw_nir.c
+++ b/src/intel/compiler/brw_nir.c
@@ -516,6 +516,8 @@ brw_nir_optimize(nir_shader *nir, const struct brw_compiler *compiler,
 
       if (is_scalar) {
          OPT(nir_lower_alu_to_scalar, NULL, NULL);
+      } else {
+         OPT(nir_opt_shrink_vectors);
       }
 
       OPT(nir_copy_prop);