On Thu, Oct 12, 2017 at 11:38 AM, Jose Maria Casanova Crespo <
jmcasan...@igalia.com> wrote:
> From: Alejandro Piñeiro <apinhe...@igalia.com>
>
> We need to rely on byte scattered writes as untyped writes are 32-bit
> size. We could try to keep using 32-bit messages when we have two or
> four 16-bit elements, but for simplicity sake, we use the same message
> for any component number. We revisit this in this serie.
>
> v2: Removed use of stride = 2 on 16-bit sources (Jason Ekstrand)
>
> Signed-off-by: Jose Maria Casanova Crespo <jmcasan...@igalia.com>
> Signed-off-by: Alejandro Piñeiro <apinhe...@igalia.com
> ---
> src/intel/compiler/brw_fs_nir.cpp | 35 +++++++++++++++++++++++++++++-
> -----
> 1 file changed, 29 insertions(+), 6 deletions(-)
>
> diff --git a/src/intel/compiler/brw_fs_nir.cpp
> b/src/intel/compiler/brw_fs_nir.cpp
> index e108b5517b..13c16fc912 100644
> --- a/src/intel/compiler/brw_fs_nir.cpp
> +++ b/src/intel/compiler/brw_fs_nir.cpp
> @@ -28,6 +28,7 @@
>
> using namespace brw;
> using namespace brw::surface_access;
> +using namespace brw::scattered_access;
>
> void
> fs_visitor::emit_nir_code()
> @@ -4085,8 +4086,15 @@ fs_visitor::nir_emit_intrinsic(const fs_builder
> &bld, nir_intrinsic_instr *instr
> * length of the write to what we can do and let the next
> iteration
> * handle the rest
> */
> - if (type_size > 4)
> + if (type_size > 4) {
>
Maybe move the above comment to here.
> length = MIN2(2, length);
> + } else if (type_size == 2) {
> + /* For 16-bit types we are using byte scattered writes, that
> can
> + * only write one component per call. So we limit the length,
> and
> + * let the write happening in several iterations.
> + */
> + length = 1;
> + }
>
> fs_reg offset_reg;
> nir_const_value *const_offset = nir_src_as_const_value(instr->
> src[2]);
> @@ -4100,11 +4108,26 @@ fs_visitor::nir_emit_intrinsic(const fs_builder
> &bld, nir_intrinsic_instr *instr
> brw_imm_ud(type_size * first_component));
> }
>
> -
> - emit_untyped_write(bld, surf_index, offset_reg,
> - offset(val_reg, bld, first_component *
> type_slots),
> - 1 /* dims */, length * type_slots,
> - BRW_PREDICATE_NONE);
> + if (type_size == 2) {
> + /* Untyped Surface messages have a fixed 32-bit size, so we
> need
> + * to rely on byte scattered in order to write 16-bit
> elements.
> + * The byte_scattered_write message needs that every written
> 16-bit
> + * type to be aligned 32-bits (stride=2).
> + */
> + fs_reg tmp = bld.vgrf(BRW_REGISTER_TYPE_F);
> + val_reg.type = BRW_REGISTER_TYPE_HF;
> + bld.MOV (subscript(tmp, BRW_REGISTER_TYPE_HF, 0),
> + offset(val_reg, bld, first_component));
>
We should probably use W types here so we don't get any float conversion
problems.
With that fixed and the previous patch squashed in,
Reviewed-by: Jason Ekstrand <ja...@jlekstrand.net>
> + emit_byte_scattered_write(bld, surf_index, offset_reg,
> + tmp,
> + 1 /* dims */, length * type_slots,
> + BRW_PREDICATE_NONE);
> + } else {
> + emit_untyped_write(bld, surf_index, offset_reg,
> + offset(val_reg, bld, first_component *
> type_slots),
> + 1 /* dims */, length * type_slots,
> + BRW_PREDICATE_NONE);
> + }
>
> /* Clear the bits in the writemask that we just wrote, then try
> * again to see if more channels are left.
> --
> 2.13.6
>
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