glsl: add subroutine index qualifier support

ARB_explicit_uniform_location allows the index for subroutine functions
to be explicitly set in the shader.

This patch reduces the restriction on the index qualifier in
validate_layout_qualifiers() to allow it to be applied to subroutines
and adds the new subroutine qualifier validation to ast_function::hir().

ast_fully_specified_type::has_qualifiers() is updated to allow the
index qualifier on subroutine functions when explicit uniform locations
is available.

A new check is added to ast_type_qualifier::merge_qualifier() to stop
multiple function qualifiers from being defied, before this patch this
would cause a segfault.

Finally a new variable is added to ir_function_signature to store the
index. This value is validated and the non explicit values assigned in
link_assign_subroutine_types().

Reviewed-by: Tapani Pälli <[email protected]>

1 files changed, 33 insertions, 0 deletions

diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index db00f8febc6..331d9a28007 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -3864,10 +3864,43 @@ link_assign_subroutine_types(struct gl_shader_program *prog)
          sh->SubroutineFunctions[sh->NumSubroutineFunctions].types =
             ralloc_array(sh, const struct glsl_type *,
                          fn->num_subroutine_types);
+
+         /* From Section 4.4.4(Subroutine Function Layout Qualifiers) of the
+          * GLSL 4.5 spec:
+          *
+          *    "Each subroutine with an index qualifier in the shader must be
+          *    given a unique index, otherwise a compile or link error will be
+          *    generated."
+          */
+         for (unsigned j = 0; j < sh->NumSubroutineFunctions; j++) {
+            if (sh->SubroutineFunctions[j].index != -1 &&
+                sh->SubroutineFunctions[j].index == fn->subroutine_index) {
+               linker_error(prog, "each subroutine index qualifier in the "
+                            "shader must be unique\n");
+               return;
+            }
+         }
+         sh->SubroutineFunctions[sh->NumSubroutineFunctions].index =
+            fn->subroutine_index;
+
          for (int j = 0; j < fn->num_subroutine_types; j++)
             sh->SubroutineFunctions[sh->NumSubroutineFunctions].types[j] = fn->subroutine_types[j];
          sh->NumSubroutineFunctions++;
       }
+
+      /* Assign index for subroutines without an explicit index*/
+      int index = 0;
+      for (unsigned j = 0; j < sh->NumSubroutineFunctions; j++) {
+         while (sh->SubroutineFunctions[j].index == -1) {
+            for (unsigned k = 0; k < sh->NumSubroutineFunctions; k++) {
+               if (sh->SubroutineFunctions[k].index == index)
+                  break;
+               else if (k == sh->NumSubroutineFunctions - 1)
+                  sh->SubroutineFunctions[j].index = index;
+            }
+            index++;
+         }
+      }
    }
 }