[Mesa-dev] [PATCH 6/8] nv50/ir: optimize ADD3(d, 0x0, b, c) to ADD(d, b, c)

[Ilia Mirkin]

On Thu, Jun 30, 2016 at 6:54 PM, Samuel Pitoiset
<samuel.pitoiset at gmail.com> wrote:
>
>
> On 07/01/2016 12:44 AM, Ilia Mirkin wrote:
>>
>> If moveSources doesn't move modifiers, we have a serious problem.
>> However it looks like it does:
>>
>> void
>> Instruction::setSrc(int s, const ValueRef& ref)
>> {
>>    setSrc(s, ref.get());
>>    srcs[s].mod = ref.mod;
>> }
>>
>> which is what moveSources calls.
>
>
> I was not sure about moveSources() because we have two variants and the
> other one doesn't move the modifiers.
>>
>>
>>
>> On Thu, Jun 30, 2016 at 6:26 PM, Samuel Pitoiset
>> <samuel.pitoiset at gmail.com> wrote:
>>>
>>> And ADD3(d, a, 0x0, c) to ADD(d, a, c) as well.
>>>
>>> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
>>> ---
>>>  src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp | 12
>>> +++++++++++-
>>>  1 file changed, 11 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
>>> b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
>>> index 1cf1fa3..517f779 100644
>>> --- a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
>>> +++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
>>> @@ -1032,7 +1032,17 @@ ConstantFolding::opnd(Instruction *i,
>>> ImmediateValue &imm0, int s)
>>>              i->src(0).mod = Modifier(0);
>>>        }
>>>        break;
>>> -
>>> +   case OP_ADD3:
>>> +      if (i->usesFlags())
>>> +         break;
>>
>>
>> Why? ADD can produce/consume a flag just fine.
>
>
> Well, this is loosely based on OP_ADD which does exactly the same check.

Right, because you can't get rid of ADD 0, $c. (There is no MOV $c
variant... or we don't support it ... we probably should, I think
that's what CSET/CSETP are.) However you can definitely flip the ADD3
into an ADD2 even if the carry flag is being added in.

>
>>
>>> +      if (imm0.isInteger(0)) {
>>> +         i->op = OP_ADD;
>>> +         for (int k = s; k < 2; k++) {
>>> +            i->setSrc(k, i->getSrc(k + 1));
>>> +            i->src(k).mod = i->src(k + 1).mod;
>>> +         }
>>
>>
>> aka
>>
>> i->moveSources(s + 1, -1) ?
>
>
> Yes.
>
>
>>
>>> +      }
>>> +      break;
>>>     case OP_DIV:
>>>        if (s != 1 || (i->dType != TYPE_S32 && i->dType != TYPE_U32))
>>>           break;
>>> --
>>> 2.8.3
>>>
>>> _______________________________________________
>>> mesa-dev mailing list
>>> mesa-dev at lists.freedesktop.org
>>> https://lists.freedesktop.org/mailman/listinfo/mesa-dev