glsl: add has_implicit_uint_to_int_conversion()-helper

This makes the code a bit easier to read, as well as reduces repetition,
especially when we add support for EXT_shader_implicit_conversions.

Signed-off-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>

src/compiler/glsl/ast_to_hir.cpp

@@ -250,8 +250,7 @@ get_implicit_conversion_operation(const glsl_type *to, const glsl_type *from,
       }
 
    case GLSL_TYPE_UINT:
-      if (!state->is_version(400, 0) && !state->ARB_gpu_shader5_enable
-          && !state->MESA_shader_integer_functions_enable)
+      if (!state->has_implicit_uint_to_int_conversion())
          return (ir_expression_operation)0;
       switch (from->base_type) {
          case GLSL_TYPE_INT: return ir_unop_i2u;

src/compiler/glsl/glsl_parser_extras.h

@@ -349,6 +349,13 @@ struct _mesa_glsl_parse_state {
       return is_version(120, 0);
    }
 
+   bool has_implicit_uint_to_int_conversion() const
+   {
+      return ARB_gpu_shader5_enable ||
+             MESA_shader_integer_functions_enable ||
+             is_version(400, 0);
+   }
+
    void process_version_directive(YYLTYPE *locp, int version,
                                   const char *ident);