Linking fails when not writing gl_Position.

According to GLSL-ES Spec(i.e. 1.0, 3.0), gl_Position value is undefined
after the vertex processing stage if we don't write gl_Position. However,
GLSL 1.10 Spec mentions that writing to gl_Position is mandatory. In case
of GLSL-ES, it's not an error and atleast the linking should pass.
Currently, Mesa throws an linker error in case we dont write to gl_position
and Version is less then 140(GLSL) and 300(GLSL-ES). This patch changes
it so that we don't report an error in case of GLSL-ES.

Signed-off-by: Kalyan Kondapally <kalyan.kondapally@intel.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=83380

diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index 57be493..e9cf550 100644 (file)
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -559,10 +559,10 @@ validate_vertex_shader_executable(struct gl_shader_program *prog,
     *      vertex processing has occurred. Its value is undefined if
     *      the vertex shader executable does not write gl_Position."
     *
-    * GLSL ES 3.00 is similar to GLSL 1.40--failing to write to gl_Position is
-    * not an error.
+    * All GLSL ES Versions are similar to GLSL 1.40--failing to write to
+    * gl_Position is not an error.
     */
-   if (prog->Version < (prog->IsES ? 300 : 140)) {
+   if (!prog->IsES && prog->Version < 140) {
       find_assignment_visitor find("gl_Position");
       find.run(shader->ir);
       if (!find.variable_found()) {