[Freedreno] [Mesa-dev] [PATCH 1/2] nir: allow texture offsets with cube maps

[Ilia Mirkin]

On Mon, Nov 20, 2017 at 7:08 PM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> On Mon, Nov 20, 2017 at 3:11 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>>
>> On Mon, Nov 20, 2017 at 5:16 PM, Jason Ekstrand <jason at jlekstrand.net>
>> wrote:
>> > On Sun, Nov 19, 2017 at 11:54 AM, Ilia Mirkin <imirkin at alum.mit.edu>
>> > wrote:
>> >>
>> >> GL doesn't have this, but some hardware supports it. This is convenient
>> >> for lowering tg4 to plain texture calls, which is necessary on Adreno
>> >> A4xx hardware.
>> >>
>> >> Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
>> >> ---
>> >>  src/compiler/nir/nir.h | 15 +++++++++++++--
>> >>  1 file changed, 13 insertions(+), 2 deletions(-)
>> >>
>> >> diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
>> >> index f46f6147110..64965ae16d6 100644
>> >> --- a/src/compiler/nir/nir.h
>> >> +++ b/src/compiler/nir/nir.h
>> >> @@ -1364,8 +1364,7 @@ nir_tex_instr_src_size(const nir_tex_instr
>> >> *instr,
>> >> unsigned src)
>> >>     if (instr->src[src].src_type == nir_tex_src_ms_mcs)
>> >>        return 4;
>> >>
>> >> -   if (instr->src[src].src_type == nir_tex_src_offset ||
>> >> -       instr->src[src].src_type == nir_tex_src_ddx ||
>> >> +   if (instr->src[src].src_type == nir_tex_src_ddx ||
>> >>         instr->src[src].src_type == nir_tex_src_ddy) {
>> >>        if (instr->is_array)
>> >>           return instr->coord_components - 1;
>> >> @@ -1373,6 +1372,18 @@ nir_tex_instr_src_size(const nir_tex_instr
>> >> *instr,
>> >> unsigned src)
>> >>           return instr->coord_components;
>> >>     }
>> >>
>> >> +   /* Usual APIs don't allow cube + offset, but we allow it, with 2
>> >> coords for
>> >> +    * the offset, since a cube maps to a single face.
>> >> +    */
>> >> +   if (instr->src[src].src_type == nir_tex_src_offset) {
>> >> +      unsigned ret = instr->coord_components;
>> >> +      if (instr->is_array)
>> >> +         ret--;
>> >> +      if (instr->sampler_dim == GLSL_SAMPLER_DIM_CUBE)
>> >> +         ret--;
>> >> +      return ret;
>> >
>> >
>> > I think I'd rather this look more like the one above:
>> >
>> > if (instr->is_array)
>> >    return instr->coord_components;
>> > else if (instr->sampler_dim == GLSL_SAMPLER_DIM_CUBE)
>> >    return 2;
>> > else
>> >    return instr->coord_components - 1;
>> >
>> > It seems a bit cleaner and/or more explicit to me.
>>
>> OK. Although your version is slightly wrong, but I get the idea. Will
>> do that in a v2. (array should get -1, and cube should always get 2
>> even if it's an array)
>
>
> I'd forgotten about cube arrays, yes, those would naturally be -2.  In that
> case, maybe -- for each subtraction is a good idea...

Well, rearranging it, we get

if (instr->sampler_dim == CUBE)
  return 2;
else if (instr->is_array)
  return comp - 1;
else
  return comp;

Happy to leave it alone too though.