[Mesa-dev] [RFC PATCH 09/10] i965/clip: Use clip distances for all user clipping

[Paul Berry]

On 3 August 2013 19:59, Chris Forbes <chrisf at ijw.co.nz> wrote:

> Signed-off-by: Chris Forbes <chrisf at ijw.co.nz>
> ---
>  src/mesa/drivers/dri/i965/brw_clip_tri.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_clip_tri.c
> b/src/mesa/drivers/dri/i965/brw_clip_tri.c
> index bd3ffb3..4d2eb0a 100644
> --- a/src/mesa/drivers/dri/i965/brw_clip_tri.c
> +++ b/src/mesa/drivers/dri/i965/brw_clip_tri.c
> @@ -241,16 +241,19 @@ load_clip_distance(struct brw_clip_compile *c,
> struct brw_indirect vtx,
>     brw_AND(p, vec1(brw_null_reg()), c->reg.vertex_src_mask,
> brw_imm_ud(1));
>     brw_IF(p, BRW_EXECUTE_1);
>     {
> -      brw_MOV(p, dst, deref_4f(vtx, clip_offset));
> +      struct brw_indirect temp_ptr = brw_indirect(7, 0);
> +      brw_ADD(p, get_addr_reg(temp_ptr), get_addr_reg(vtx),
> c->reg.clipdistance_offset);
> +      brw_MOV(p, vec1(dst), deref_1f(temp_ptr, 0));
>     }
>     brw_ELSE(p);
>     {
>        brw_MOV(p, dst, deref_4f(vtx, hpos_offset));
> +      brw_DP4(p, dst, dst, c->reg.plane_equation);
>     }
>     brw_ENDIF(p);
>
>     brw_set_conditionalmod(p, cond);
> -   brw_DP4(p, dst, dst, c->reg.plane_equation);
> +   brw_CMP(p, brw_null_reg(), cond, vec1(dst), brw_imm_f(0.0f));
>  }
>

I think you can use one less instruction if you do this instead:

   brw_IF(p, BRW_EXECUTE_1);
   {
      struct brw_indirect temp_ptr = brw_indirect(7, 0);
      brw_ADD(p, get_addr_reg(temp_ptr), get_addr_reg(vtx),
c->reg.clipdistance_offset);
      brw_set_conditionalmod(p, cond);
      brw_MOV(p, vec1(dst), deref_1f(temp_ptr, 0));
   }
   brw_ELSE(p);
   {
      brw_MOV(p, dst, deref_4f(vtx, hpos_offset));
      brw_set_conditionalmod(p, cond);
      brw_DP4(p, dst, dst, c->reg.plane_equation);
   }
   brw_ENDIF(p);

But I haven't tried it so it's possible that it doesn't work for some
non-obvious reason :)

In any case, this patch is:

Reviewed-by: Paul Berry <stereotype441 at gmail.com>
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