glsl: Compile error if fs defines conflicting qualifiers for gl_FragCoord

GLSL 1.50 spec says:
   "If gl_FragCoord is redeclared in any fragment shader in a program,
    it must be redeclared in all the fragment shaders in that
    program that have a static use gl_FragCoord. All redeclarations of
    gl_FragCoord in all fragment shaders in a single program must
    have the same set of qualifiers."

This patch makes the glsl compiler to generate an error if we have a
fragment shader defined with conflicting layout qualifier declarations
for gl_FragCoord. For example:

layout(origin_upper_left, pixel_center_integer) in vec4 gl_FragCoord;
layout(pixel_center_integer) in vec4 gl_FragCoord;

void main()
{
}

V2: Some code refactoring for better readability.
    Add compiler error conditions for redeclarations like:

layout(origin_upper_left) in vec4 gl_FragCoord;
layout(origin_upper_left, pixel_center_integer) in vec4 gl_FragCoord;

and

in vec4 gl_FragCoord;
layout(origin_upper_left, pixel_center_integer) in vec4 gl_FragCoord;

V3: Simplify function is_conflicting_fragcoord_redeclaration()
V4: Check for null pointer before doing strcmp(var->name, "gl_FragCoord").

Signed-off-by: Anuj Phogat <[email protected]>
Cc: <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>

1 files changed, 12 insertions, 0 deletions

diff --git a/src/glsl/glsl_parser_extras.h b/src/glsl/glsl_parser_extras.h
index 3ad205c07f2..e3db877be49 100644
--- a/src/glsl/glsl_parser_extras.h
+++ b/src/glsl/glsl_parser_extras.h
@@ -200,6 +200,18 @@ struct _mesa_glsl_parse_state {
    struct ast_type_qualifier *default_uniform_qualifier;
 
    /**
+    * Variables to track different cases if a fragment shader redeclares
+    * built-in variable gl_FragCoord.
+    *
+    * Note: These values are computed at ast_to_hir time rather than at parse
+    * time.
+    */
+   bool fs_redeclares_gl_fragcoord;
+   bool fs_origin_upper_left;
+   bool fs_pixel_center_integer;
+   bool fs_redeclares_gl_fragcoord_with_no_layout_qualifiers;
+
+   /**
     * True if a geometry shader input primitive type was specified using a
     * layout directive.
     *