[Mesa-dev] [PATCH v4 23/44] i965/fs: Enables 16-bit load_ubo with sampler (v2)

[Jason Ekstrand]

Looks good to me.

On Tue, Dec 5, 2017 at 3:47 PM, Jose Maria Casanova Crespo <
jmcasanova at igalia.com> wrote:

> From: Jason Ekstrand <jason.ekstrand at intel.com>
>
> load_ubo is using 32-bit loads as uniforms surfaces have a 32-bit
> surface format defined. So when reading 16-bit components with the
> sampler we need to unshuffle two 16-bit components from each 32-bit
> component.
>
> Using the sampler avoids the use of the byte_scattered_read message
> that needs one message for each component and is supposed to be
> slower.
>
> v2: (Jason Ekstrand)
>     - Simplify component selection and unshuffling for different bitsizes
>     - Remove SKL optimization of reading only two 32-bit components when
>       reading 16-bits types.
>
> Reviewed-by: Jose Maria Casanova Crespo <jmcasanova at igalia.com>
> ---
>  src/intel/compiler/brw_fs.cpp | 21 ++++++++++++++-------
>  1 file changed, 14 insertions(+), 7 deletions(-)
>
> diff --git a/src/intel/compiler/brw_fs.cpp b/src/intel/compiler/brw_fs.cpp
> index 91399c6c1d..93bb6b4673 100644
> --- a/src/intel/compiler/brw_fs.cpp
> +++ b/src/intel/compiler/brw_fs.cpp
> @@ -191,14 +191,21 @@ fs_visitor::VARYING_PULL_CONSTANT_LOAD(const
> fs_builder &bld,
>                              vec4_result, surf_index, vec4_offset);
>     inst->size_written = 4 * vec4_result.component_size(inst->exec_size);
>
> -   if (type_sz(dst.type) == 8) {
> -      shuffle_32bit_load_result_to_64bit_data(
> -         bld, retype(vec4_result, dst.type), vec4_result, 2);
> +   fs_reg dw = offset(vec4_result, bld, (const_offset & 0xf) / 4);
> +   switch (type_sz(dst.type)) {
> +   case 2:
> +      shuffle_32bit_load_result_to_16bit_data(bld, dst, dw, 1);
> +      bld.MOV(dst, subscript(dw, dst.type, (const_offset / 2) & 1));
> +      break;
> +   case 4:
> +      bld.MOV(dst, retype(dw, dst.type));
> +      break;
> +   case 8:
> +      shuffle_32bit_load_result_to_64bit_data(bld, dst, dw, 1);
> +      break;
> +   default:
> +      unreachable("Unsupported bit_size");
>     }
> -
> -   vec4_result.type = dst.type;
> -   bld.MOV(dst, offset(vec4_result, bld,
> -                       (const_offset & 0xf) / type_sz(vec4_result.type)));
>  }
>
>  /**
> --
> 2.14.3
>
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