[Mesa-dev] [PATCH 4/5] i965/ir: Pass identity mask to brw_find_live_channel() in the packed dispatch case.

[Jason Ekstrand]

As I said on patch 5, I would like to see some version of it merged at
least for fs.  The vec4 back-end isn't as much of a problem since we've
verified it now and future hardware won't be using it.

Series is Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>

On Sep 16, 2016 3:04 PM, "Francisco Jerez" <currojerez at riseup.net> wrote:

> This avoids emitting a few extra instructions required to take the
> dispatch mask into account when it's known to be tightly packed.
> ---
>  src/mesa/drivers/dri/i965/brw_fs_generator.cpp   | 4 +++-
>  src/mesa/drivers/dri/i965/brw_vec4_generator.cpp | 8 ++++++--
>  2 files changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
> b/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
> index c510f42..bdeda3b 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs_generator.cpp
> @@ -2045,7 +2045,9 @@ fs_generator::generate_code(const cfg_t *cfg, int
> dispatch_width)
>
>        case SHADER_OPCODE_FIND_LIVE_CHANNEL: {
>           const struct brw_reg mask =
> -            stage == MESA_SHADER_FRAGMENT ? brw_vmask_reg() :
> brw_dmask_reg();
> +            brw_stage_has_packed_dispatch(stage, prog_data) ?
> brw_imm_ud(~0u) :
> +            stage == MESA_SHADER_FRAGMENT ? brw_vmask_reg() :
> +            brw_dmask_reg();
>           brw_find_live_channel(p, dst, mask);
>           break;
>        }
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4_generator.cpp
> b/src/mesa/drivers/dri/i965/brw_vec4_generator.cpp
> index f9e6d1c..2bef549 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4_generator.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4_generator.cpp
> @@ -1862,9 +1862,13 @@ generate_code(struct brw_codegen *p,
>           brw_memory_fence(p, dst);
>           break;
>
> -      case SHADER_OPCODE_FIND_LIVE_CHANNEL:
> -         brw_find_live_channel(p, dst, brw_dmask_reg());
> +      case SHADER_OPCODE_FIND_LIVE_CHANNEL: {
> +         const struct brw_reg mask =
> +            brw_stage_has_packed_dispatch(nir->stage, &prog_data->base) ?
> +            brw_imm_ud(~0u) : brw_dmask_reg();
> +         brw_find_live_channel(p, dst, mask);
>           break;
> +      }
>
>        case SHADER_OPCODE_BROADCAST:
>           assert(inst->force_writemask_all);
> --
> 2.9.0
>
>
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