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/drivers/dri/i965/brw_link.cpp b/src/mesa/drivers/dri/i965/brw_link.cpp
index f0598f591ab..b08b56a9353 100644
--- a/src/mesa/drivers/dri/i965/brw_link.cpp
+++ b/src/mesa/drivers/dri/i965/brw_link.cpp
@@ -99,7 +99,8 @@ process_glsl_ir(struct brw_context *brw,
 
    ralloc_adopt(mem_ctx, shader->ir);
 
-   lower_blend_equation_advanced(shader);
+   lower_blend_equation_advanced(
+      shader, ctx->Extensions.KHR_blend_equation_advanced_coherent);
 
    /* lower_packing_builtins() inserts arithmetic instructions, so it
     * must precede lower_instructions().