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 <[email protected]>
Reviewed-by: Jordan Justen <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>

1 files changed, 4 insertions, 4 deletions

diff --git a/src/glsl/lower_clip_distance.cpp b/src/glsl/lower_clip_distance.cpp
index 09bdc36e169..643807de87b 100644
--- a/src/glsl/lower_clip_distance.cpp
+++ b/src/glsl/lower_clip_distance.cpp
@@ -301,8 +301,8 @@ lower_clip_distance_visitor::visit_leave(ir_call *ir)
          this->base_ir->insert_before(temp_clip_distance);
          actual_param->replace_with(
             new(ctx) ir_dereference_variable(temp_clip_distance));
-         if (formal_param->mode == ir_var_in
-             || formal_param->mode == ir_var_inout) {
+         if (formal_param->mode == ir_var_function_in
+             || formal_param->mode == ir_var_function_inout) {
             /* Copy from gl_ClipDistance to the temporary before the call.
              * Since we are going to insert this copy before the current
              * instruction, we need to visit it afterwards to make sure it
@@ -314,8 +314,8 @@ lower_clip_distance_visitor::visit_leave(ir_call *ir)
             this->base_ir->insert_before(new_assignment);
             this->visit_new_assignment(new_assignment);
          }
-         if (formal_param->mode == ir_var_out
-             || formal_param->mode == ir_var_inout) {
+         if (formal_param->mode == ir_var_function_out
+             || formal_param->mode == ir_var_function_inout) {
             /* Copy from the temporary to gl_ClipDistance after the call.
              * Since visit_list_elements() has already decided which
              * instruction it's going to visit next, we need to visit