[Mesa-dev] [PATCH v2 19/30] i965/fs: add shuffle_64bit_data_for_32bit_write helper

[Francisco Jerez]

Samuel Iglesias Gonsálvez <siglesias at igalia.com> writes:

> From: Iago Toral Quiroga <itoral at igalia.com>
>
> This does the inverse operation of shuffle_32bit_load_result_to_64bit_data
> and we will use it when we need to write 64-bit data in the layout expected
> by untyped write messages.
>
> v2 (curro):
> - Use subscript() instead of stride()
> - Assert on the input types rather than silently retyping.
> - Use offset() instead of horiz_offset(), drop the multiplier definition.
> - Drop the temporary vgrf and force_writemask_all.
> - Make component_i const.
> ---
>  src/mesa/drivers/dri/i965/brw_fs.cpp | 40 ++++++++++++++++++++++++++++++++++++
>  src/mesa/drivers/dri/i965/brw_fs.h   |  5 +++++
>  2 files changed, 45 insertions(+)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
> index ebc5128..3c58ccb 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
> @@ -280,6 +280,46 @@ fs_visitor::shuffle_32bit_load_result_to_64bit_data(const fs_builder &bld,
>  }
>  
>  /**
> + * This helper does the inverse operation of
> + * SHUFFLE_32BIT_LOAD_RESULT_TO_64BIT_DATA.
> + *
> + * We need to do this when we are going to use untyped write messsages that
> + * operate with 32-bit components in order to arrange our 64-bit data to be
> + * in the expected layout.
> + */
> +void
> +fs_visitor::shuffle_64bit_data_for_32bit_write(const fs_builder &bld,
> +                                               const fs_reg dst,
> +                                               const fs_reg src,
> +                                               uint32_t components)
> +{
> +   assert(type_sz(src.type) == 8);
> +   assert(type_sz(dst.type) == 4);
> +
> +   /* A temporary that we will use to shuffle the 64-bit data of each
> +    * component in the vector into valid 32-bit data that we can write.
> +    * We can't write directly to dst because dst can be (and would usually be)
> +    * the same as src and in that case the first MOV in the loop below would
> +    * overwrite the data read in the second MOV.
> +    */
> +   fs_reg tmp = retype(bld.vgrf(src.type), dst.type);
> +

This is just 'bld.vgrf(dst.type, 2)' as I suggested off-list, other than
that:

Reviewed-by: Francisco Jerez <currojerez at riseup.net>

> +   for (unsigned i = 0; i < components; i++) {
> +      const fs_reg component_i = offset(src, bld, i);
> +
> +      bld.MOV(tmp, subscript(component_i, dst.type, 0));
> +      bld.MOV(offset(tmp, bld, 1), subscript(component_i, dst.type, 1));
> +
> +      /* Because we are shuffling our 64-bit data to a 32-bit layout, we
> +       * need these MOVs to be 32-bit (instead of doing this as a single
> +       * DF MOV), otherwise we would not be respecting the channel enables.
> +       */
> +      bld.MOV(offset(dst, bld, 2 * i), tmp);
> +      bld.MOV(offset(dst, bld, 2 * i + 1), offset(tmp, bld, 1));
> +   }
> +}
> +
> +/**
>   * A helper for MOV generation for fixing up broken hardware SEND dependency
>   * handling.
>   */
> diff --git a/src/mesa/drivers/dri/i965/brw_fs.h b/src/mesa/drivers/dri/i965/brw_fs.h
> index 1aeacae..4c17ff4 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs.h
> +++ b/src/mesa/drivers/dri/i965/brw_fs.h
> @@ -110,6 +110,11 @@ public:
>                                                  const fs_reg src,
>                                                  uint32_t components);
>  
> +   void shuffle_64bit_data_for_32bit_write(const brw::fs_builder &bld,
> +                                           const fs_reg dst,
> +                                           const fs_reg src,
> +                                           uint32_t components);
> +
>     void do_untyped_vector_read(const brw::fs_builder &bld,
>                                 const fs_reg surf_index,
>                                 const fs_reg offset_reg,
> -- 
> 2.5.0
>
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