glsl: Specify framebuffer fetch coherency mode in lower_blend_equation_advanced().

This requires passing an extra argument to the lowering pass because
the KHR_blend_equation_advanced specification doesn't seem to define
any mechanism for the implementation to determine at compile-time
whether coherent blending can ever be used (not even an "#extension
KHR_blend_equation_advanced_coherent" directive seems to be required
in the shader source AFAICT).

In the long run we'll probably want to do state-dependent recompiles
based on the value of ctx->Color.BlendCoherent, but right now there
would be no benefit from that because the only driver that supports
coherent framebuffer fetch is i965 on SKL+ hardware, which are unable
to support the non-coherent path for the moment because of texture
layout issues, so framebuffer fetch coherency is always enabled for
them.

Reviewed-by: Plamena Manolova <[email protected]>

1 files changed, 2 insertions, 1 deletions

diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
index 7fef93949e8..ccf4dabcc9f 100644
--- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
@@ -7056,7 +7056,8 @@ st_link_shader(struct gl_context *ctx, struct gl_shader_program *prog)
       do_mat_op_to_vec(ir);
 
       if (stage == MESA_SHADER_FRAGMENT)
-         lower_blend_equation_advanced(shader);
+         lower_blend_equation_advanced(
+            shader, ctx->Extensions.KHR_blend_equation_advanced_coherent);
 
       lower_instructions(ir,
                          MOD_TO_FLOOR |