On 01/19/2014 12:16 AM, Ilia Mirkin wrote:
Hi,
My goal is to extend shader-db to be able to be used with nouveau, as
I'm about to attempt a few compiler optimizations. But I'm having
trouble with the very first step -- getting the driver to spit out the
generated code. I've added logic to nouveau to translate the program
as soon as it's available rather than on first use. However it seems
that mesa/st has similar delaying logic, which makes it so that none
of this is called when merely calling glLinkProgram.
Right. The issue is "shader variants". It's often the case that misc
GL state interacts with the VS/FS code. For example, depending on
whether we're drawing to the window or an FBO we have to invert the Y
coordinate of gl_FragCoord in the FS by creating a FS variant. We
postpone creating/bind shader variants until draw time, just like other
state validation.
I'm having trouble figuring out how to bypass this and make it call
update_vp/fp/gp which appear like they'll actually call
pipe->create_fs_state/etc. I see st_link_shader getting called, as
expected, which creates the TGSI... but what to do from there?
If you were to short-circuit the validation steps above and force the
VS/FS to get propagated to the driver ASAP, there's a chance the shader
wouldn't actually do everything that it normally would (ex: invert Y).
I don't know if that matters to you.
In any case, there's no simple solution to this. You'll probably have
to hack something up. If it turns out simple, maybe we could enable it
with a debug flag.
-Brian
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