radeonsi: add 16-bit ALU vectorization

Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6622>
diff --git a/src/gallium/drivers/radeonsi/si_shader_nir.c b/src/gallium/drivers/radeonsi/si_shader_nir.c
index 171c2b3..66fca2b 100644
--- a/src/gallium/drivers/radeonsi/si_shader_nir.c
+++ b/src/gallium/drivers/radeonsi/si_shader_nir.c
@@ -560,6 +560,9 @@
       if (nir->options->max_unroll_iterations) {
          NIR_PASS(progress, nir, nir_opt_loop_unroll, 0);
       }
+
+      if (sscreen->info.has_packed_math_16bit)
+         NIR_PASS(progress, nir, nir_opt_vectorize, NULL, NULL);
    } while (progress);
 }