[Mesa-dev] [PATCH 2/2] nir: Add support for CSE on textures.

[Eric Anholt]

Jason Ekstrand <jason at jlekstrand.net> writes:

> On Wed, Aug 12, 2015 at 11:55 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.
>>
>> Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
>> ---
>>  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 553906e..864795c 100644
>> --- a/src/glsl/nir/nir_opt_cse.c
>> +++ b/src/glsl/nir/nir_opt_cse.c
>> @@ -86,8 +86,41 @@ 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;
>
> We should probably loop over both arrays of sources and match by
> source type instead of assuming that they are always in the same
> order.  They *probably* are, but you can pretty easily get cases where
> they aren't.
>
> Otherwise, this looks fine to me.

What circumstance would produce arrays in different order?  I can't
imagine one, so conservative seems appropriate to me.
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