[Mesa-dev] [PATCH v2 39/53] intel/compiler: add a helper to do conversions between integer and half-float

[Francisco Jerez]

Iago Toral Quiroga <itoral at igalia.com> writes:

> There are hardware restrictions to consider that seem to affect atom platforms
> only.

Same comment here as for PATCH 13 of this series.  This and PATCH 40
shouldn't be necessary anymore with [1] in place.  Please drop them.

[1] https://lists.freedesktop.org/archives/mesa-dev/2018-December/212775.html

> ---
>  src/intel/compiler/brw_fs_nir.cpp | 32 +++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
>
> diff --git a/src/intel/compiler/brw_fs_nir.cpp b/src/intel/compiler/brw_fs_nir.cpp
> index 802f5cb0944..a9fd98bab68 100644
> --- a/src/intel/compiler/brw_fs_nir.cpp
> +++ b/src/intel/compiler/brw_fs_nir.cpp
> @@ -696,6 +696,38 @@ fixup_64bit_conversion(const fs_builder &bld,
>     return false;
>  }
>  
> +static bool
> +fixup_int_half_float_conversion(const fs_builder &bld,
> +                                fs_reg dst, fs_reg src,
> +                                bool saturate,
> +                                const struct gen_device_info *devinfo)
> +{
> +   /* CHV PRM, 3D Media GPGPU Engine, Register Region Restrictions,
> +    * Special Restrictions:
> +    *
> +    *    "Conversion between Integer and HF (Half Float) must be DWord
> +    *     aligned and strided by a DWord on the destination."
> +    *
> +    * The same restriction is listed for other hardware platforms, however,
> +    * empirical testing suggests that only atom platforms are affected.
> +    */
> +   if (!devinfo->is_cherryview && !gen_device_info_is_9lp(devinfo))
> +      return false;
> +
> +   if (!((dst.type == BRW_REGISTER_TYPE_HF && !brw_reg_type_is_floating_point(src.type)) ||
> +         (src.type == BRW_REGISTER_TYPE_HF && !brw_reg_type_is_floating_point(dst.type))))
> +      return false;
> +
> +   fs_reg tmp = horiz_stride(retype(bld.vgrf(BRW_REGISTER_TYPE_F, 1),
> +                                    dst.type),
> +                             2);
> +   bld.MOV(tmp, src);
> +   fs_inst *inst = bld.MOV(dst, tmp);
> +   inst->saturate = saturate;
> +
> +   return true;
> +}
> +
>  void
>  fs_visitor::nir_emit_alu(const fs_builder &bld, nir_alu_instr *instr)
>  {
> -- 
> 2.17.1
>
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