[Mesa-dev] [PATCH 09/36] i965: new VS: move clip distance computation (GEN5+) to a separate function.

[Eric Anholt]

On Fri,  2 Sep 2011 09:06:48 -0700, Paul Berry <stereotype441 at gmail.com> wrote:
> ---
>  src/mesa/drivers/dri/i965/brw_vec4.h           |    1 +
>  src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp |   32 ++++++++++++++---------
>  2 files changed, 20 insertions(+), 13 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4.h b/src/mesa/drivers/dri/i965/brw_vec4.h
> index 8c613bd..01313ec 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4.h
> +++ b/src/mesa/drivers/dri/i965/brw_vec4.h
> @@ -465,6 +465,7 @@ public:
>  
>     void emit_ndc_computation();
>     void emit_psiz_and_flags(struct brw_reg reg);
> +   void emit_clip_distances(struct brw_reg reg, int offset);
>     int emit_vue_header_gen6(int header_mrf);
>     int emit_vue_header_gen4(int header_mrf);
>     void emit_urb_writes(void);
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
> index bd8878a..374cf8a 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
> @@ -1789,6 +1789,21 @@ vec4_visitor::emit_psiz_and_flags(struct brw_reg reg)
>     }
>  }
>  
> +void
> +vec4_visitor::emit_clip_distances(struct brw_reg reg, int offset)
> +{
> +   if (intel->gen < 6)
> +      /* Clip distance slots are set aside in gen5 because the hardware
> +       * requires them to be, but they are not used. */
> +      return;

Style consistency nits for the day: I like to see braces for if
statements with a multi-line then case.  Also, before your patch series
there were only 15 instances of cuddling the "*/" onto the last line of
a multi-line comment in our driver.

And now for some actual review: The hardware doesn't actually require
the clip distance slots on gen5, we just fail to set up the hardware to
not use them.  I made a patch series at one point to do that, but given
that I couldn't measure a performance difference and I was already
living in fear of our VUE setup, I never pushed it.
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