glsl: Eliminate ambiguity between function ins/outs and shader ins/outs

This patch replaces the three ir_variable_mode enums:

- ir_var_in
- ir_var_out
- ir_var_inout

with the following five:

- ir_var_shader_in
- ir_var_shader_out
- ir_var_function_in
- ir_var_function_out
- ir_var_function_inout

This eliminates a frustrating ambiguity: it used to be impossible to
tell whether an ir_var_{in,out} variable was a shader in/out or a
function in/out without seeing where the variable was declared in the
IR.  This complicated some optimization and lowering passes, and would
have become a problem for implementing varying structs.

In the lisp-style serialization of GLSL IR to strings performed by
ir_print_visitor.cpp and ir_reader.cpp, I've retained the names "in",
"out", and "inout" for function parameters, to avoid introducing code
churn to the src/glsl/builtins/ir/ directory.

Note: a couple of comments in the code seemed to indicate that we were
planning for a possible future in which geometry shaders could have
shader-scope inout variables.  Our GLSL grammar rejects shader-scope
inout variables, and I've been unable to find any evidence in the GLSL
standards documents (or extensions) that this will ever be allowed, so
I've eliminated these comments.

Reviewed-by: Carl Worth <cworth@cworth.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/glsl/ir_function.cpp b/src/glsl/ir_function.cpp
index a525693..fe4209c 100644
--- a/src/glsl/ir_function.cpp
+++ b/src/glsl/ir_function.cpp
@@ -78,17 +78,17 @@ parameter_lists_match(const exec_list *list_a, const exec_list *list_b)
 	 return PARAMETER_LIST_NO_MATCH;
 
       case ir_var_const_in:
-      case ir_var_in:
+      case ir_var_function_in:
 	 if (!actual->type->can_implicitly_convert_to(param->type))
 	    return PARAMETER_LIST_NO_MATCH;
 	 break;
 
-      case ir_var_out:
+      case ir_var_function_out:
 	 if (!param->type->can_implicitly_convert_to(actual->type))
 	    return PARAMETER_LIST_NO_MATCH;
 	 break;
 
-      case ir_var_inout:
+      case ir_var_function_inout:
 	 /* Since there are no bi-directional automatic conversions (e.g.,
 	  * there is int -> float but no float -> int), inout parameters must
 	  * be exact matches.