glsl: Handle the inout qualifier in fragment shader output declarations.

According to the EXT_shader_framebuffer_fetch extension the inout
qualifier can be used on ESSL 3.0+ shaders to declare a special kind
of fragment output that gets implicitly initialized with the previous
framebuffer contents at the current fragment coordinates.  In addition
we allow using the same language to define FB fetch outputs in GLSL
1.3+ shaders in preparation for the desktop MESA_shader_framebuffer_fetch
extensions.

Reviewed-by: Kenneth Graunke <[email protected]>

2 files changed, 16 insertions, 1 deletions

diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp
index c05fb17cabe..c91ed539623 100644
--- a/src/compiler/glsl/ast_to_hir.cpp
+++ b/src/compiler/glsl/ast_to_hir.cpp
@@ -3713,7 +3713,7 @@ apply_type_qualifier_to_variable(const struct ast_type_qualifier *qual,
     */
    assert(var->data.mode != ir_var_temporary);
    if (qual->flags.q.in && qual->flags.q.out)
-      var->data.mode = ir_var_function_inout;
+      var->data.mode = is_parameter ? ir_var_function_inout : ir_var_shader_out;
    else if (qual->flags.q.in)
       var->data.mode = is_parameter ? ir_var_function_in : ir_var_shader_in;
    else if (qual->flags.q.attribute
@@ -3730,6 +3730,9 @@ apply_type_qualifier_to_variable(const struct ast_type_qualifier *qual,
    else if (qual->flags.q.shared_storage)
       var->data.mode = ir_var_shader_shared;
 
+   var->data.fb_fetch_output = state->stage == MESA_SHADER_FRAGMENT &&
+                               qual->flags.q.in && qual->flags.q.out;
+
    if (!is_parameter && is_varying_var(var, state->stage)) {
       /* User-defined ins/outs are not permitted in compute shaders. */
       if (state->stage == MESA_SHADER_COMPUTE) {
diff --git a/src/compiler/glsl/glsl_parser.yy b/src/compiler/glsl/glsl_parser.yy
index 5b6586141d8..f2853da0848 100644
--- a/src/compiler/glsl/glsl_parser.yy
+++ b/src/compiler/glsl/glsl_parser.yy
@@ -1944,6 +1944,18 @@ storage_qualifier:
           $$.xfb_buffer = state->out_qualifier->xfb_buffer;
       }
    }
+   | INOUT_TOK
+   {
+      memset(& $$, 0, sizeof($$));
+      $$.flags.q.in = 1;
+      $$.flags.q.out = 1;
+
+      if (!state->has_framebuffer_fetch() ||
+          !state->is_version(130, 300) ||
+          state->stage != MESA_SHADER_FRAGMENT)
+         _mesa_glsl_error(&@1, state, "A single interface variable cannot be "
+                          "declared as both input and output");
+   }
    | UNIFORM
    {
       memset(& $$, 0, sizeof($$));