[Vm-dev] Cog Primitive Performance

[Ben Coman]

On Wed, Apr 19, 2017 at 3:42 AM, Bert Freudenberg <bert at freudenbergs.de>
wrote:

>
> On Tue, Apr 18, 2017 at 9:04 PM, Eliot Miranda <eliot.miranda at gmail.com>
> wrote:
>
>>
>> Hi Bert, Hi All,
>>
>> On Tue, Apr 18, 2017 at 10:55 AM, Bert Freudenberg <bert at freudenbergs.de>
>> wrote:
>>
>>>
>>> On Tue, Apr 18, 2017 at 6:09 PM, Nicolas Cellier <
>>> nicolas.cellier.aka.nice at gmail.com> wrote:
>>>
>>>>
>>>> Concerning the specific case of hashMultiply, since it's just an imul
>>>> and a bitAnd, the primitive should be inlined by the VM just like other
>>>> basic arithmetic operations IMO.
>>>> So the remarks of Andres makes sense, even if we can't generalize to
>>>> other Misc primitives.
>>>>
>>>
>>> Yes, code optimized by Sista should be pretty much as fast as a
>>> primitive, so we could hopefully get rid of many primitives that are just
>>> there to improve performance.
>>>
>>
>> The problem to think through carefully is the impact on the
>> ContextInterpreter, StackInterpreter and SqueakJS VMs.  I have a gut
>> feeling that the right thing to do is to keep the primitives for the
>> benefit of these VMs and to have Cog ignore them.
>>
>
> Ah, good point.
>

By ignore, do you mean excluded from the built binary by conditional
compilation, to minimise VM size for embedded platforms?

cheers -ben


>
>
>> That implies that the primitive failure code can be what one would like
>> to execute and have Sista optimize.  That means that translated primitives
>> are an obstacle.
>>
>
> Agreed.
>
>
>> Rewriting the translated primitives as conventional primitives in
>> MiscPrimitivePlugin and not including the MiscPrimitivePlugin in Cog (JIT)
>> VMs (o including one which provides no primitives) would allow the
>> primitive failure code in the various Collection methods to be written
>> optimally, allow the interpreter VMs to keep using the primitives, allow
>> Cog VMs to ignore the primitives easily, and would allow putting the
>> primitives closer to the receivers.  Redirecting through to the class side
>> wastes cycles.
>>
>
> Yep :)
>
> - Bert -
>
>
>
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