[Mesa-dev] Status of the GLSL->TGSI translator

[Bryan Cain]

On Thu, Jun 16, 2011 at 9:08 AM, Brian Paul <brianp at vmware.com> wrote:
>
>
> Looks like nice work, Bryan.
>
> Just a few minor questions/comments for now:
>
> 1. The st_fragment/vertex/geometry_program structs now have a glsl_to_tgsi
> field.  I did a grep, but I couldn't find where that field is assigned.  Can
> you clue me in?
>

It's assigned at the end of the get_mesa_program function in
st_glsl_to_tgsi.cpp.


>
> 2. The above mentioned program structs contains an old Mesa instruction
> program AND/OR(?) a GLSL IR.  Do both types of representations co-exist
> sometimes?  Perhaps you could update the comments on those structs to
> explain that.
>

They used to co-exist, because after my first commit, st_glsl_to_tgsi still
generated Mesa IR in addition to TGSI.  But I removed the Mesa IR generation
in "st/mesa: stop generating Mesa IR in st_glsl_to_tgsi", so now it has
either one or the other - glsl_to_tgsi_visitor for GLSL shaders, Mesa IR
programs for everything else.


>
> 3. Kind of a follow-on: for glDrawPixels and glBitmap we take the original
> program code (in Mesa form) and prepend extra instructions for fetching the
> fragment color or doing the fragment kill.  Do we always have the Mesa
> instructions for this?  It seems we don't normally want to generate Mesa
> instructions all the time but we still need them sometimes.
>

No, I didn't realize Mesa did that, and we don't have the Mesa instructions
for GLSL programs anymore.  I'm not sure what the right way to handle that
is.


>
> 4. At least one commit message is slightly mis-named: changes to the
> gallium/util/tgsi/ files were labeled as "softpipe".  Not a big deal, but
> maybe be more careful about that.
>

I thought only softpipe used tgsi_exec, but I'll keep in mind to be more
careful in the future.
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