nir: Support deref instructions in opt_undef

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

v2: Use correct src index for store_deref (Bas)

src/compiler/nir/nir_opt_undef.c

@@ -107,19 +107,24 @@ opt_undef_vecN(nir_builder *b, nir_alu_instr *alu)
 static bool
 opt_undef_store(nir_intrinsic_instr *intrin)
 {
+   unsigned src_index = 0;
    switch (intrin->intrinsic) {
+   case nir_intrinsic_store_deref:
+      src_index = 1;
+      break;
    case nir_intrinsic_store_var:
    case nir_intrinsic_store_output:
    case nir_intrinsic_store_per_vertex_output:
    case nir_intrinsic_store_ssbo:
    case nir_intrinsic_store_shared:
+      src_index = 0;
       break;
    default:
       return false;
    }
 
-   if (!intrin->src[0].is_ssa ||
-       intrin->src[0].ssa->parent_instr->type != nir_instr_type_ssa_undef)
+   if (!intrin->src[src_index].is_ssa ||
+       intrin->src[src_index].ssa->parent_instr->type != nir_instr_type_ssa_undef)
       return false;
 
    nir_instr_remove(&intrin->instr);
@@ -133,8 +138,6 @@ nir_opt_undef(nir_shader *shader)
    nir_builder b;
    bool progress = false;
 
-   nir_assert_lowered_derefs(shader, nir_lower_load_store_derefs);
-
    nir_foreach_function(function, shader) {
       if (function->impl) {
          nir_builder_init(&b, function->impl);