nir: Add a pass to lower vector phi nodes to scalar phi nodes

v2 Jason Ekstrand <[email protected]>:
 - Add better comments
 - Use nir_ssa_dest_init and nir_src_for_ssa more places
 - Fix some void * casts

v3 Jason Ekstrand <[email protected]>:
 - Rework the way we determine whether or not to sccalarize a phi node to
   make the recursion non-bogus
 - Treat load_const instructions as scalarizable

v4 Jason Ekstrand <[email protected]>:
 - Allow uniform and input loads to be scalarizable

v5 Jason Ekstrand <[email protected]>:
 - Also consider loads of inputs (varying, uniform, or ubo) to be
   scalarizable.  We were already doing this for load_var on uniforms and
   inputs.

Reviewed-by: Kenneth Graunke <[email protected]>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h
index 98d26896019..866ac5d4751 100644
--- a/src/glsl/nir/nir.h
+++ b/src/glsl/nir/nir.h
@@ -1527,6 +1527,8 @@ void nir_remove_dead_variables(nir_shader *shader);
 void nir_lower_vec_to_movs(nir_shader *shader);
 void nir_lower_alu_to_scalar(nir_shader *shader);
 
+void nir_lower_phis_to_scalar(nir_shader *shader);
+
 void nir_lower_samplers(nir_shader *shader,
                         struct gl_shader_program *shader_program,
                         struct gl_program *prog);