Connor Abbott <cwabbo...@gmail.com> writes:
> On Wed, Feb 11, 2015 at 2:36 PM, Eric Anholt <e...@anholt.net> wrote:
>> Connor Abbott <cwabbo...@gmail.com> writes:
>>
>>> On Tue, Feb 10, 2015 at 1:32 PM, Eric Anholt <e...@anholt.net> wrote:
>>>> Connor Abbott <cwabbo...@gmail.com> writes:
>>>>
>>>>> On Sat, Feb 7, 2015 at 12:16 AM, Eric Anholt <e...@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?
>
> because in 99% of cases, that's what we want. To be clear, I'm not
> against initializing stuff to some default value when it makes sense,
> and in this case I'm fine with initializing all the sometimes-used
> things to 0 and ensuring that they stay 0 to make comparing
> tex_instr's less of a PITA. But I don't think we should be blindly
> calling calloc()/rzalloc() on everything; if there's some field the
> caller has to set, and there's no default value that 99% of callers
> will want, don't set it and then let valgrind find any errors (or,
> even better, pass it as a parameter to the constructor). And yes,
> there are probably a few places where we initialize stuff when it's
> not necessary -- that's a mistake on my part.What I most object to about not calling calloc/rzalloc is that it means you don't get to find the errors you've created until you happen to run under valgrind, since you almost always get zero-filled contents anyway.
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