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_set_program_inouts.cpp b/src/glsl/ir_set_program_inouts.cpp
index e5de07e..1e102bf 100644
--- a/src/glsl/ir_set_program_inouts.cpp
+++ b/src/glsl/ir_set_program_inouts.cpp
@@ -85,7 +85,7 @@ mark(struct gl_program *prog, ir_variable *var, int offset, int len,
 
    for (int i = 0; i < len; i++) {
       GLbitfield64 bitfield = BITFIELD64_BIT(var->location + var->index + offset + i);
-      if (var->mode == ir_var_in) {
+      if (var->mode == ir_var_shader_in) {
 	 prog->InputsRead |= bitfield;
          if (is_fragment_shader) {
             gl_fragment_program *fprog = (gl_fragment_program *) prog;
@@ -152,8 +152,8 @@ ir_set_program_inouts_visitor::visit_enter(ir_dereference_array *ir)
 ir_visitor_status
 ir_set_program_inouts_visitor::visit(ir_variable *ir)
 {
-   if (ir->mode == ir_var_in ||
-       ir->mode == ir_var_out ||
+   if (ir->mode == ir_var_shader_in ||
+       ir->mode == ir_var_shader_out ||
        ir->mode == ir_var_system_value) {
       hash_table_insert(this->ht, ir, ir);
    }