[Mesa-dev] [PATCH 7/8] i965/vs: Enable SPF when the shader contains no control flow.

[Chia-I Wu]

On Wed, May 7, 2014 at 9:38 AM, Matt Turner <mattst88 at gmail.com> wrote:
> ---
>  src/mesa/drivers/dri/i965/gen6_vs_state.c | 3 ++-
>  src/mesa/drivers/dri/i965/gen7_vs_state.c | 3 ++-
>  src/mesa/drivers/dri/i965/gen8_vs_state.c | 3 ++-
>  3 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/gen6_vs_state.c b/src/mesa/drivers/dri/i965/gen6_vs_state.c
> index 0af87d1..bdfb9b5 100644
> --- a/src/mesa/drivers/dri/i965/gen6_vs_state.c
> +++ b/src/mesa/drivers/dri/i965/gen6_vs_state.c
> @@ -167,7 +167,8 @@ upload_vs_state(struct brw_context *brw)
>     OUT_BATCH(floating_point_mode |
>              ((ALIGN(stage_state->sampler_count, 4)/4) << GEN6_VS_SAMPLER_COUNT_SHIFT) |
>               ((brw->vs.prog_data->base.base.binding_table.size_bytes / 4) <<
> -              GEN6_VS_BINDING_TABLE_ENTRY_COUNT_SHIFT));
> +              GEN6_VS_BINDING_TABLE_ENTRY_COUNT_SHIFT) |
> +             (!brw->vs.prog_data->base.has_control_flow ? GEN6_VS_SPF_MODE : 0));
The doc says bit 31 is "Single Vertex Dispatch".  When this bit is
set, I vaguely remember VS_INVOCATION_COUNT does get doubled for the
same workload, and the performance is hurt.

>
>     if (brw->vs.prog_data->base.total_scratch) {
>        OUT_RELOC(stage_state->scratch_bo,
> diff --git a/src/mesa/drivers/dri/i965/gen7_vs_state.c b/src/mesa/drivers/dri/i965/gen7_vs_state.c
> index b5fc871..f9c9abc 100644
> --- a/src/mesa/drivers/dri/i965/gen7_vs_state.c
> +++ b/src/mesa/drivers/dri/i965/gen7_vs_state.c
> @@ -97,7 +97,8 @@ upload_vs_state(struct brw_context *brw)
>              ((ALIGN(stage_state->sampler_count, 4)/4) <<
>                GEN6_VS_SAMPLER_COUNT_SHIFT) |
>               ((brw->vs.prog_data->base.base.binding_table.size_bytes / 4) <<
> -              GEN6_VS_BINDING_TABLE_ENTRY_COUNT_SHIFT));
> +              GEN6_VS_BINDING_TABLE_ENTRY_COUNT_SHIFT) |
> +             (!brw->vs.prog_data->base.has_control_flow ? GEN6_VS_SPF_MODE : 0));
>
>     if (brw->vs.prog_data->base.total_scratch) {
>        OUT_RELOC(stage_state->scratch_bo,
> diff --git a/src/mesa/drivers/dri/i965/gen8_vs_state.c b/src/mesa/drivers/dri/i965/gen8_vs_state.c
> index 373cfe4..a83d78b 100644
> --- a/src/mesa/drivers/dri/i965/gen8_vs_state.c
> +++ b/src/mesa/drivers/dri/i965/gen8_vs_state.c
> @@ -85,7 +85,8 @@ upload_vs_state(struct brw_context *brw)
>               ((ALIGN(stage_state->sampler_count, 4) / 4) <<
>                 GEN6_VS_SAMPLER_COUNT_SHIFT) |
>               ((prog_data->base.binding_table.size_bytes / 4) <<
> -               GEN6_VS_BINDING_TABLE_ENTRY_COUNT_SHIFT));
> +               GEN6_VS_BINDING_TABLE_ENTRY_COUNT_SHIFT) |
> +             (!brw->vs.prog_data->base.has_control_flow ? GEN6_VS_SPF_MODE : 0));
>
>     if (prog_data->total_scratch) {
>        OUT_RELOC64(stage_state->scratch_bo,
> --
> 1.8.3.2
>
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