[Mesa-dev] [PATCH 01/12] i965: Change fragment input related bitfields to 64-bit.

[Kenneth Graunke]

On 03/12/2013 10:39 PM, Paul Berry wrote:
> On 12 March 2013 22:23, Kenneth Graunke <kenneth at whitecape.org
> <mailto:kenneth at whitecape.org>> wrote:
>
>     On 03/11/2013 03:51 PM, Paul Berry wrote:
>
>         This patch updates the bitfields brw_context::wm.input_size___masks,
>         tracker::size_masks, and brw_wm_prog_key::proj_attrib___mask, all of
>         which are indexed by gl_frag_attrib, from 32-bit to 64-bit.
>
>         This paves the way for supporting geometry shaders, and for merging
>         the gl_frag_attrib and gl_vert_result enums.  The combination of
>         these
>         two will require at least 55 bits in the bitfields.
>         ---
>            src/mesa/drivers/dri/i965/brw___context.h     |  2 +-
>            src/mesa/drivers/dri/i965/brw___fs.cpp        |  7 ++++---
>            src/mesa/drivers/dri/i965/brw___vs_constval.c | 18
>         +++++++++---------
>            src/mesa/drivers/dri/i965/brw___wm.c          |  2 +-
>            src/mesa/drivers/dri/i965/brw___wm.h          |  2 +-
>            5 files changed, 16 insertions(+), 15 deletions(-)
>
>
>     Your patch looks good.  However, I hate this code, and so seeing
>     your patch inspired me to re-measure whether the optimization is
>     actually still worth doing.  Turns out, it isn't: it actually makes
>     performance slightly -worse- in the game it was supposed to help.
>
>     So I've sent out a series to delete all this.  Hopefully, if Eric
>     agrees, we can just throw it out and you can drop this patch.
>
>     Sorry for the trouble!
>
>     --Ken
>
>
> Oh, I would be delighted to see this go away.  Earlier today I found
> myself wondering what effect geometry shaders are going to have on this
> code--it would sure be nice not to have to worry about it.

Yeah, I found myself wondering that tonight as well, and I really didn't 
want to think about it.

Probably no effect, actually, since it shouldn't ever have any effect 
when a GLSL vertex shader is active, and that's required to have a 
geometry shader active.  But..."shouldn't". :)  I wouldn't be surprised 
if there were bugs.