[Mesa-dev] [PATCH 2/2] radeonsi: move PSIZE and CLIPDIST unique IO indices after GENERIC

[Marek Olšák]

Ping

On Sat, Jun 3, 2017 at 6:04 PM, Marek Olšák <maraeo at gmail.com> wrote:
> From: Marek Olšák <marek.olsak at amd.com>
>
> Heaven LDS usage for LS+HS is below. The masks are "outputs_written"
> for LS and HS. Note that 32K is the maximum size.
>
> Before:
>   heaven_x64: ls=1f1 tcs=1f1, lds=32K
>   heaven_x64: ls=31 tcs=31, lds=24K
>   heaven_x64: ls=71 tcs=71, lds=28K
>
> After:
>   heaven_x64: ls=3f tcs=3f, lds=24K
>   heaven_x64: ls=7 tcs=7, lds=13K
>   heaven_x64: ls=f tcs=f, lds=17K
>
> All other apps have a similar decrease in LDS usage, because
> the "outputs_written" masks are similar. Also, most apps don't write
> POSITION in these shader stages, so there is room for improvement.
> (tight per-component input/output packing might help even more)
>
> It's unknown whether this improves performance.
> ---
>  src/gallium/drivers/radeonsi/si_shader.c        | 18 +++++++++++-------
>  src/gallium/drivers/radeonsi/si_state_shaders.c |  4 +++-
>  2 files changed, 14 insertions(+), 8 deletions(-)
>
> diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
> index ddfaa3b..3a86c0b 100644
> --- a/src/gallium/drivers/radeonsi/si_shader.c
> +++ b/src/gallium/drivers/radeonsi/si_shader.c
> @@ -129,32 +129,36 @@ unsigned si_shader_io_get_unique_index_patch(unsigned semantic_name, unsigned in
>  /**
>   * Returns a unique index for a semantic name and index. The index must be
>   * less than 64, so that a 64-bit bitmask of used inputs or outputs can be
>   * calculated.
>   */
>  unsigned si_shader_io_get_unique_index(unsigned semantic_name, unsigned index)
>  {
>         switch (semantic_name) {
>         case TGSI_SEMANTIC_POSITION:
>                 return 0;
> -       case TGSI_SEMANTIC_PSIZE:
> -               return 1;
> -       case TGSI_SEMANTIC_CLIPDIST:
> -               assert(index <= 1);
> -               return 2 + index;
>         case TGSI_SEMANTIC_GENERIC:
> +               /* Since some shader stages use the the highest used IO index
> +                * to determine the size to allocate for inputs/outputs
> +                * (in LDS, tess and GS rings). GENERIC should be placed right
> +                * after POSITION to make that size as small as possible.
> +                */
>                 if (index < SI_MAX_IO_GENERIC)
> -                       return 4 + index;
> +                       return 1 + index;
>
>                 assert(!"invalid generic index");
>                 return 0;
> -
> +       case TGSI_SEMANTIC_PSIZE:
> +               return SI_MAX_IO_GENERIC + 1;
> +       case TGSI_SEMANTIC_CLIPDIST:
> +               assert(index <= 1);
> +               return SI_MAX_IO_GENERIC + 2 + index;
>         case TGSI_SEMANTIC_FOG:
>                 return SI_MAX_IO_GENERIC + 4;
>         case TGSI_SEMANTIC_LAYER:
>                 return SI_MAX_IO_GENERIC + 5;
>         case TGSI_SEMANTIC_VIEWPORT_INDEX:
>                 return SI_MAX_IO_GENERIC + 6;
>         case TGSI_SEMANTIC_PRIMID:
>                 return SI_MAX_IO_GENERIC + 7;
>         case TGSI_SEMANTIC_COLOR: /* these alias */
>         case TGSI_SEMANTIC_BCOLOR:
> diff --git a/src/gallium/drivers/radeonsi/si_state_shaders.c b/src/gallium/drivers/radeonsi/si_state_shaders.c
> index 8ac4309..f36997b 100644
> --- a/src/gallium/drivers/radeonsi/si_state_shaders.c
> +++ b/src/gallium/drivers/radeonsi/si_state_shaders.c
> @@ -1226,21 +1226,23 @@ static void si_shader_selector_key_hw_vs(struct si_context *sctx,
>                 ps_disabled = sctx->queued.named.rasterizer->rasterizer_discard ||
>                               (!ps_colormask &&
>                                !ps_modifies_zs &&
>                                !ps->info.writes_memory);
>         }
>
>         /* Find out which VS outputs aren't used by the PS. */
>         uint64_t outputs_written = vs->outputs_written;
>         uint64_t inputs_read = 0;
>
> -       outputs_written &= ~0x3; /* ignore POSITION, PSIZE */
> +       /* ignore POSITION, PSIZE */
> +       outputs_written &= ~((1ull << si_shader_io_get_unique_index(TGSI_SEMANTIC_POSITION, 0) |
> +                            (1ull << si_shader_io_get_unique_index(TGSI_SEMANTIC_PSIZE, 0))));
>
>         if (!ps_disabled) {
>                 inputs_read = ps->inputs_read;
>         }
>
>         uint64_t linked = outputs_written & inputs_read;
>
>         key->opt.hw_vs.kill_outputs = ~linked & outputs_written;
>  }
>
> --
> 2.7.4
>