[Mesa-dev] [PATCH 01/14] intel/compiler: general 8/16/32/64-bit shuffle_src_to_dst function
Jason Ekstrand
jason at jlekstrand.net
Wed Jun 13 20:46:31 UTC 2018
On Sat, Jun 9, 2018 at 4:13 AM, Jose Maria Casanova Crespo <
jmcasanova at igalia.com> wrote:
> This new function takes care of shuffle/unshuffle components of a
> particular bit-size in components with a different bit-size.
>
> If source type size is smaller than destination type size the operation
> needed is a component shuffle. The opposite case would be an unshuffle.
>
> The operation allows to skip first_component number of components from
> the source.
>
> Shuffle MOVs are retyped using integer types avoiding problems with denorms
> and float types. This allows to simplify uses of shuffle functions that are
> dealing with these retypes individually.
>
> Now there is a new restriction so source and destination can not overlap
> anymore when calling this suffle function. Following patches that migrate
> to use this new function will take care individually of avoiding source
> and destination overlaps.
> ---
> src/intel/compiler/brw_fs_nir.cpp | 92 +++++++++++++++++++++++++++++++
> 1 file changed, 92 insertions(+)
>
> diff --git a/src/intel/compiler/brw_fs_nir.cpp
> b/src/intel/compiler/brw_fs_nir.cpp
> index 166da0aa6d7..1a9d3c41d1d 100644
> --- a/src/intel/compiler/brw_fs_nir.cpp
> +++ b/src/intel/compiler/brw_fs_nir.cpp
> @@ -5362,6 +5362,98 @@ shuffle_16bit_data_for_32bit_write(const
> fs_builder &bld,
> }
> }
>
> +/*
> + * This helper takes a source register and un/shuffles it into the
> destination
> + * register.
> + *
> + * If source type size is smaller than destination type size the operation
> + * needed is a component shuffle. The opposite case would be an
> unshuffle. If
> + * source/destination type size is equal a shuffle is done that would be
> + * equivalent to a simple MOV.
>
There's a sticky bit here if we want this to work with 64-bit types on gen7
and earlier because we only have DF there and not Q so the
brw_reg_type_from_bit_size below doesn't work. If we care about that case
(and I'm not convinced we do), it should be easy enough to add a
type_sz(src.type) == type_sz(dst.type) case which just does MOVs from
source to dest.
> + *
> + * For example, if source is a 16-bit type and destination is 32-bit. A 3
> + * components .xyz 16-bit vector on SIMD8 would be.
> + *
> + * |x1|x2|x3|x4|x5|x6|x7|x8|y1|y2|y3|y4|y5|y6|y7|y8|
> + * |z1|z2|z3|z4|z5|z6|z7|z8| | | | | | | | |
> + *
> + * This helper will return the following 2 32-bit components with the
> 16-bit
> + * values shuffled:
> + *
> + * |x1 y1|x2 y2|x3 y3|x4 y4|x5 y5|x6 y6|x7 y7|x8 y8|
> + * |z1 |z2 |z3 |z4 |z5 |z6 |z7 |z8 |
> + *
> + * For unshuffle, the example would be the opposite, a 64-bit type source
> + * and a 32-bit destination. A 2 component .xy 64-bit vector on SIMD8
> + * would be:
> + *
> + * | x1l x1h | x2l x2h | x3l x3h | x4l x4h |
> + * | x5l x5h | x6l x6h | x7l x7h | x8l x8h |
> + * | y1l y1h | y2l y2h | y3l y3h | y4l y4h |
> + * | y5l y5h | y6l y6h | y7l y7h | y8l y8h |
> + *
> + * The returned result would be the following 4 32-bit components
> unshuffled:
> + *
> + * | x1l | x2l | x3l | x4l | x5l | x6l | x7l | x8l |
> + * | x1h | x2h | x3h | x4h | x5h | x6h | x7h | x8h |
> + * | y1l | y2l | y3l | y4l | y5l | y6l | y7l | y8l |
> + * | y1h | y2h | y3h | y4h | y5h | y6h | y7h | y8h |
> + *
> + * - Source and destination register must not be overlapped.
> + * - first_component parameter allows skipping source components.
> + */
> +void
> +shuffle_src_to_dst(const fs_builder &bld,
> + const fs_reg &dst,
> + const fs_reg &src,
> + uint32_t first_component,
> + uint32_t components)
> +{
> + if (type_sz(src.type) <= type_sz(dst.type)) {
> + /* Source is shuffled into destination */
> + unsigned size_ratio = type_sz(dst.type) / type_sz(src.type);
> +#ifndef NDEBUG
> + boolean src_dst_overlap = regions_overlap(dst,
> + type_sz(dst.type) * bld.dispatch_width() * components,
> + offset(src, bld, first_component * size_ratio),
>
Why do you need to multiply first_component by size_ratio? It's already in
units of source components.
> + type_sz(src.type) * bld.dispatch_width() * components *
> size_ratio);
> +#endif
> + assert(!src_dst_overlap);
>
If the only thing you're doing with src_dst_overlap is to assert on it, you
may as well put the regions_overlap call inside the assert and drop the
#ifndef.
> +
> + brw_reg_type shuffle_type =
> + brw_reg_type_from_bit_size(8 * type_sz(src.type),
> + BRW_REGISTER_TYPE_D);
> + for (unsigned i = 0; i < components; i++) {
> + fs_reg shuffle_component_i =
> + subscript(offset(dst, bld, i / size_ratio),
> + shuffle_type, i % size_ratio);
> + bld.MOV(shuffle_component_i,
> + retype(offset(src, bld, i + first_component),
> shuffle_type));
> + }
> + } else {
> + /* Source is unshuffled into destination */
> + unsigned size_ratio = type_sz(src.type) / type_sz(dst.type);
> +#ifndef NDEBUG
> + boolean src_dst_overlap = regions_overlap(dst,
> + type_sz(dst.type) * bld.dispatch_width() * components,
> + offset(src, bld, first_component / size_ratio),
>
Again, I don't think we want to divide here.
> + type_sz(src.type) * bld.dispatch_width() *
> + DIV_ROUND_UP(components + first_component % size_ratio,
> size_ratio));
> +#endif
> + assert(!src_dst_overlap);
>
As I said above, everything can go in the assert.
Other than that, this looks great.
--Jason
> + brw_reg_type shuffle_type =
> + brw_reg_type_from_bit_size(8 * type_sz(dst.type),
> + BRW_REGISTER_TYPE_D);
> + for (unsigned i = 0; i < components; i++) {
> + fs_reg shuffle_component_i =
> + subscript(offset(src, bld, (first_component + i) /
> size_ratio),
> + shuffle_type, (first_component + i) % size_ratio);
> + bld.MOV(retype(offset(dst, bld, i), shuffle_type),
> + shuffle_component_i);
> + }
> + }
> +}
> +
> fs_reg
> setup_imm_df(const fs_builder &bld, double v)
> {
> --
> 2.17.1
>
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