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]>

4 files changed, 11 insertions, 9 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_fs_fp.cpp b/src/mesa/drivers/dri/i965/brw_fs_fp.cpp
index 9ca082a0fc9..5f5f6a9ba76 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_fp.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_fp.cpp
@@ -610,7 +610,7 @@ fs_visitor::setup_fp_regs()
           */
          ir_variable *ir = new(mem_ctx) ir_variable(glsl_type::vec4_type,
                                                     "fp_input",
-                                                    ir_var_in);
+                                                    ir_var_shader_in);
          ir->location = i;
 
          this->current_annotation = ralloc_asprintf(ctx, "interpolate input %d",
diff --git a/src/mesa/drivers/dri/i965/brw_fs_vector_splitting.cpp b/src/mesa/drivers/dri/i965/brw_fs_vector_splitting.cpp
index 7a12e084ff8..b9487532c59 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_vector_splitting.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_vector_splitting.cpp
@@ -110,11 +110,13 @@ ir_vector_reference_visitor::get_variable_entry(ir_variable *var)
 
    switch (var->mode) {
    case ir_var_uniform:
-   case ir_var_in:
-   case ir_var_out:
-   case ir_var_inout:
+   case ir_var_shader_in:
+   case ir_var_shader_out:
+   case ir_var_function_in:
+   case ir_var_function_out:
+   case ir_var_function_inout:
       /* Can't split varyings or uniforms.  Function in/outs won't get split
-       * either, so don't care about the ambiguity.
+       * either.
        */
       return NULL;
    case ir_var_auto:
diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
index 5885989e76e..ebb37fd3113 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
@@ -57,7 +57,7 @@ fs_visitor::visit(ir_variable *ir)
    if (variable_storage(ir))
       return;
 
-   if (ir->mode == ir_var_in) {
+   if (ir->mode == ir_var_shader_in) {
       if (!strcmp(ir->name, "gl_FragCoord")) {
 	 reg = emit_fragcoord_interpolation(ir);
       } else if (!strcmp(ir->name, "gl_FrontFacing")) {
@@ -68,7 +68,7 @@ fs_visitor::visit(ir_variable *ir)
       assert(reg);
       hash_table_insert(this->variable_ht, reg, ir);
       return;
-   } else if (ir->mode == ir_var_out) {
+   } else if (ir->mode == ir_var_shader_out) {
       reg = new(this->mem_ctx) fs_reg(this, ir->type);
 
       if (ir->index > 0) {
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
index d9ff869f2da..cff04ba887c 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
@@ -905,11 +905,11 @@ vec4_visitor::visit(ir_variable *ir)
       return;
 
    switch (ir->mode) {
-   case ir_var_in:
+   case ir_var_shader_in:
       reg = new(mem_ctx) dst_reg(ATTR, ir->location);
       break;
 
-   case ir_var_out:
+   case ir_var_shader_out:
       reg = new(mem_ctx) dst_reg(this, ir->type);
 
       for (int i = 0; i < type_size(ir->type); i++) {