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

[Eric Anholt]

Connor Abbott <cwabbott0 at gmail.com> writes:

> On Tue, Feb 10, 2015 at 1:32 PM, Eric Anholt <eric at anholt.net> wrote:
>> Connor Abbott <cwabbott0 at gmail.com> writes:
>>
>>> 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.
>>
>> Oh god, we don't zero-allocate structures.  This is going to be awful.
>
> No, with valgrind it's actually better... you get an error if you
> don't know what you're doing rather than silently having it ignored.
> These days, zero-allocating structures by default doesn't make much
> sense any more.

So, why should nir.c not be zero-filling those fields, when we zero fill
the nir_dests and nir_srcs and and tex->sampler and tex->sampler_index
and deref->base_offset?
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