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, 7 insertions, 10 deletions

diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
index 1d96e905c1e..575636e6e57 100644
--- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
@@ -2001,21 +2001,18 @@ glsl_to_tgsi_visitor::visit(ir_dereference_variable *ir)
         				       var->location);
          this->variables.push_tail(entry);
          break;
-      case ir_var_in:
-      case ir_var_inout:
+      case ir_var_shader_in:
          /* The linker assigns locations for varyings and attributes,
           * including deprecated builtins (like gl_Color), user-assign
           * generic attributes (glBindVertexLocation), and
           * user-defined varyings.
-          *
-          * FINISHME: We would hit this path for function arguments.  Fix!
           */
          assert(var->location != -1);
          entry = new(mem_ctx) variable_storage(var,
                                                PROGRAM_INPUT,
                                                var->location);
          break;
-      case ir_var_out:
+      case ir_var_shader_out:
          assert(var->location != -1);
          entry = new(mem_ctx) variable_storage(var,
                                                PROGRAM_OUTPUT,
@@ -2304,7 +2301,7 @@ glsl_to_tgsi_visitor::visit(ir_assignment *ir)
       assert(!ir->lhs->type->is_scalar() && !ir->lhs->type->is_vector());
       l.writemask = WRITEMASK_XYZW;
    } else if (ir->lhs->type->is_scalar() &&
-              ir->lhs->variable_referenced()->mode == ir_var_out) {
+              ir->lhs->variable_referenced()->mode == ir_var_shader_out) {
       /* FINISHME: This hack makes writing to gl_FragDepth, which lives in the
        * FINISHME: W component of fragment shader output zero, work correctly.
        */
@@ -2581,8 +2578,8 @@ glsl_to_tgsi_visitor::visit(ir_call *ir)
       ir_rvalue *param_rval = (ir_rvalue *)iter.get();
       ir_variable *param = (ir_variable *)sig_iter.get();
 
-      if (param->mode == ir_var_in ||
-          param->mode == ir_var_inout) {
+      if (param->mode == ir_var_function_in ||
+          param->mode == ir_var_function_inout) {
          variable_storage *storage = find_variable_storage(param);
          assert(storage);
 
@@ -2617,8 +2614,8 @@ glsl_to_tgsi_visitor::visit(ir_call *ir)
       ir_rvalue *param_rval = (ir_rvalue *)iter.get();
       ir_variable *param = (ir_variable *)sig_iter.get();
 
-      if (param->mode == ir_var_out ||
-          param->mode == ir_var_inout) {
+      if (param->mode == ir_var_function_out ||
+          param->mode == ir_var_function_inout) {
          variable_storage *storage = find_variable_storage(param);
          assert(storage);