[Mesa-dev] [PATCH] anv/gen7_pipeline: Set PixelShaderKillPixel when needed

[Nanley Chery]

On Thu, Aug 04, 2016 at 08:07:08PM -0700, Jason Ekstrand wrote:
> Drp... There's more work to do here to get the behavior 100% correct on
> gen7 but this fixes a bug and is a step in the right direction.
> 

You're right. To be more accurate, I'll rename the commit title to:
"anv/gen7_pipeline: Set PixelShaderKillPixel for discards"

> Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>

Thanks for the review!

> 
> Unfortunately, gen7 is a bit crazy so the simple solution doesn't cover all
> the cases.  For the full fix take a look at
> 
> https://cgit.freedesktop.org/mesa/mesa/tree/src/mesa/drivers/dri/i965/gen7_wm_state.c#n74

It'd probably be good for me to totally hook up this field while I'm in
the area, so I'll put it on my TODO (though I'm fine with anyone picking
this up). I'd send out a v2 which does this, but I would need to spend a
decent amount of time ramping up on all the interactions with this
field.

> 
> and
> 
> https://cgit.freedesktop.org/mesa/mesa/tree/src/mesa/drivers/dri/i965/gen7_wm_state.c#n81

This condition seems strange. The docs seem to say:
if (GEN7_WM_DISPATCH_ENABLE == 0)
   GEN7_WM_KILL_ENABLE = 0;

but i965 does:
if (GEN7_WM_KILL_ENABLE == 1)
   GEN7_WM_DISPATCH_ENABLE = 1;

> 
> and maybe
> 
> https://cgit.freedesktop.org/mesa/mesa/tree/src/mesa/drivers/dri/i965/gen7_wm_state.c#n119

I don't understand how this field is related.

- Nanley

> 
> --Jason
> 
> On Aug 4, 2016 4:45 PM, "Nanley Chery" <nanleychery at gmail.com> wrote:
> 
> > According to the IVB PRM Vol2 P1, this bit must be set if a pixel shader
> > contains a discard instruction.
> >
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97207
> > Cc: "12.0" <mesa-stable at lists.freedesktop.org>
> > Signed-off-by: Nanley Chery <nanley.g.chery at intel.com>
> > ---
> >  src/intel/vulkan/gen7_pipeline.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/src/intel/vulkan/gen7_pipeline.c b/src/intel/vulkan/gen7_
> > pipeline.c
> > index 8ce50be..d1b18e0 100644
> > --- a/src/intel/vulkan/gen7_pipeline.c
> > +++ b/src/intel/vulkan/gen7_pipeline.c
> > @@ -297,6 +297,7 @@ genX(graphics_pipeline_create)(
> >           wm.LineEndCapAntialiasingRegionWidth   = 0; /* 0.5 pixels */
> >           wm.LineAntialiasingRegionWidth         = 1; /* 1.0 pixels */
> >           wm.PointRasterizationRule              = RASTRULE_UPPER_RIGHT;
> > +         wm.PixelShaderKillPixel                = wm_prog_data->uses_kill;
> >           wm.PixelShaderComputedDepthMode        =
> > wm_prog_data->computed_depth_mode;
> >           wm.PixelShaderUsesSourceDepth          =
> > wm_prog_data->uses_src_depth;
> >           wm.PixelShaderUsesSourceW              =
> > wm_prog_data->uses_src_w;
> > --
> > 2.9.0
> >
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