[Mesa-dev] [PATCH 09/17] glsl: Handle the inout qualifier in fragment shader output declarations.

[Francisco Jerez]

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.
---
 src/compiler/glsl/ast_to_hir.cpp |  5 ++++-
 src/compiler/glsl/glsl_parser.yy | 12 ++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp
index 3b00b69..c050a3f 100644
--- a/src/compiler/glsl/ast_to_hir.cpp
+++ b/src/compiler/glsl/ast_to_hir.cpp
@@ -3682,7 +3682,7 @@ 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
@@ -3699,6 +3699,9 @@ 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 3885688..7d2c030 100644
--- a/src/compiler/glsl/glsl_parser.yy
+++ b/src/compiler/glsl/glsl_parser.yy
@@ -1952,6 +1952,18 @@ 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($$));
-- 
2.9.0