[Mesa-dev] [PATCH 1/3] nir: Add support for CSE on textures.

[Connor Abbott]

On Sat, Feb 7, 2015 at 12:16 AM, Eric Anholt <eric at anholt.net> wrote:
> NIR instruction count results on i965:
> total instructions in shared programs: 1261954 -> 1261937 (-0.00%)
> instructions in affected programs:     455 -> 438 (-3.74%)
>
> One in yofrankie, two in tropics.  Apparently i965 had also optimized all
> of these out anyway.
> ---
>  src/glsl/nir/nir_opt_cse.c | 43 +++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 39 insertions(+), 4 deletions(-)
>
> diff --git a/src/glsl/nir/nir_opt_cse.c b/src/glsl/nir/nir_opt_cse.c
> index b3e9c0d..55dc083 100644
> --- a/src/glsl/nir/nir_opt_cse.c
> +++ b/src/glsl/nir/nir_opt_cse.c
> @@ -80,8 +80,41 @@ nir_instrs_equal(nir_instr *instr1, nir_instr *instr2)
>        }
>        return true;
>     }
> -   case nir_instr_type_tex:
> -      return false;
> +   case nir_instr_type_tex: {
> +      nir_tex_instr *tex1 = nir_instr_as_tex(instr1);
> +      nir_tex_instr *tex2 = nir_instr_as_tex(instr2);
> +
> +      if (tex1->op != tex2->op)
> +         return false;
> +
> +      if (tex1->num_srcs != tex2->num_srcs)
> +         return false;
> +      for (unsigned i = 0; i < tex1->num_srcs; i++) {
> +         if (tex1->src[i].src_type != tex2->src[i].src_type ||
> +             !nir_srcs_equal(tex1->src[i].src, tex2->src[i].src)) {
> +            return false;
> +         }
> +      }
> +
> +      if (tex1->coord_components != tex2->coord_components ||
> +          tex1->sampler_dim != tex2->sampler_dim ||
> +          tex1->is_array != tex2->is_array ||
> +          tex1->is_shadow != tex2->is_shadow ||
> +          tex1->is_new_style_shadow != tex2->is_new_style_shadow ||
> +          memcmp(tex1->const_offset, tex2->const_offset,
> +                 sizeof(tex1->const_offset)) != 0 ||
> +          tex1->component != tex2->component ||
> +         tex1->sampler_index != tex2->sampler_index ||
> +         tex1->sampler_array_size != tex2->sampler_array_size) {

I think some of these fields are sometimes unused, so you need to
split them out and not check them if they're unused. For example,
is_new_style_shadow is only used when is_shadow is true, and component
isn't used if we're not doing a textureGather (?) op -- I don't
remember all the details. That, or we have to have a defined value for
these fields when they're unused and document that somewhere.

> +         return false;
> +      }
> +
> +      /* Don't support un-lowered sampler derefs currently. */
> +      if (tex1->sampler || tex2->sampler)
> +         return false;
> +
> +      return true;
> +   }
>     case nir_instr_type_load_const: {
>        nir_load_const_instr *load1 = nir_instr_as_load_const(instr1);
>        nir_load_const_instr *load2 = nir_instr_as_load_const(instr2);
> @@ -173,11 +206,10 @@ nir_instr_can_cse(nir_instr *instr)
>
>     switch (instr->type) {
>     case nir_instr_type_alu:
> +   case nir_instr_type_tex:
>     case nir_instr_type_load_const:
>     case nir_instr_type_phi:
>        return true;
> -   case nir_instr_type_tex:
> -      return false; /* TODO */
>     case nir_instr_type_intrinsic: {
>        const nir_intrinsic_info *info =
>           &nir_intrinsic_infos[nir_instr_as_intrinsic(instr)->intrinsic];
> @@ -204,6 +236,9 @@ nir_instr_get_dest_ssa_def(nir_instr *instr)
>     case nir_instr_type_alu:
>        assert(nir_instr_as_alu(instr)->dest.dest.is_ssa);
>        return &nir_instr_as_alu(instr)->dest.dest.ssa;
> +   case nir_instr_type_tex:
> +      assert(nir_instr_as_tex(instr)->dest.is_ssa);
> +      return &nir_instr_as_tex(instr)->dest.ssa;
>     case nir_instr_type_load_const:
>        return &nir_instr_as_load_const(instr)->def;
>     case nir_instr_type_phi:
> --
> 2.1.4
>
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