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On Sat, Jun 3, 2017 at 6:04 PM, Marek Olšák <mar...@gmail.com> wrote:
> From: Marek Olšák <marek.ol...@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
>
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