The TGSI FBFETCH instruction is used for implementing framebuffer-reads
when doing for instance advanced blends. It's used by both
EXT_shader_framebuffer_fetch_non_coherent and
KHR_blend_equation_advanced.
Sadly, libepoxy doesn't yet support the glFramebufferFetchBarrierEXT
function needed to implement this on top of
EXT_shader_framebuffer_fetch_non_coherent itself, so let's just implement
it on top of EXT_shader_framebuffer_fetch instead for now.
This means that we'll have slightly higher requirements for enabling
this functionality than the level of functionality we provide through it.
Signed-off-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>