anv/pipeline: Lower more constant initializers earlier

Once we've gotten rid of everything but the main entrypoint, there's no
reason why we should go ahead and lower them all.  This is what radv
does and it will make future work easier.

Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>

src/intel/vulkan/anv_pipeline.c

    assert(exec_list_length(&nir->functions) == 1);
    entry_point->name = ralloc_strdup(entry_point, "main");
 
-   /* Make sure we lower constant initializers on output variables so that
-    * nir_remove_dead_variables below sees the corresponding stores
+   /* Now that we've deleted all but the main function, we can go ahead and
+    * lower the rest of the constant initializers.  We do this here so that
+    * nir_remove_dead_variables and split_per_member_structs below see the
+    * corresponding stores.
     */
-   NIR_PASS_V(nir, nir_lower_constant_initializers, nir_var_shader_out);
+   NIR_PASS_V(nir, nir_lower_constant_initializers, ~0);
 
    NIR_PASS_V(nir, nir_remove_dead_variables,
               nir_var_shader_in | nir_var_shader_out | nir_var_system_value);
    if (stage == MESA_SHADER_FRAGMENT)
       NIR_PASS_V(nir, nir_lower_wpos_center, pipeline->sample_shading_enable);
 
-   /* Now that we've deleted all but the main function, we can go ahead and
-    * lower the rest of the constant initializers.
-    */
-   NIR_PASS_V(nir, nir_lower_constant_initializers, ~0);
    NIR_PASS_V(nir, nir_propagate_invariant);
    NIR_PASS_V(nir, nir_lower_io_to_temporaries,
               entry_point->impl, true, false);