[Vm-dev] Re: [squeak-dev] uncompacting classes

Eliot Miranda eliot.miranda at gmail.com
Tue Nov 29 21:27:23 UTC 2011


On Tue, Nov 29, 2011 at 11:54 AM, Mariano Martinez Peck <
marianopeck at gmail.com> wrote:

>
>
>
> On Mon, Nov 28, 2011 at 7:25 PM, Eliot Miranda <eliot.miranda at gmail.com>wrote:
>
>>
>>
>>
>> On Sat, Nov 26, 2011 at 3:02 PM, Chris Muller <asqueaker at gmail.com>wrote:
>>
>>> Compact classes cannot be made uncompact in a Cog+JIT VM.
>>>
>>
>> Not exactly true.  Certain classes cannot be uncompacted.  These are as
>> defined by
>>     StackInterpreter>>#checkAssumedCompactClasses
>> and the ones that can't be uncompacted are
>> Array
>> LargeNegativeInteger
>>  LargePositiveInteger
>> Float
>> MethodContext
>>
>> There is a performance advantage to being able to identify instances of
>> these classes from the compact class index.
>>
>> But any other classes should be able to be compacted and uncompacted.
>>
>
>
> Eliot, should we validate this in image side (#becomeUncompact)  ?
>

I suppose so.  The "right" way to do this would be to ask the VM (via a
primitive) for the set of assumed compact classes, but that's too much
work.  I hope that a new GC/object representation will become available
before I would ever think of changing the set of compact classes, so having
the method document what the current VM requires is ok.


>
>
>>
>>
>>> Can compact classes be made uncompact when running the StackInterpreter
>>> VM?
>>>
>>
>> It is exactly the same story.  The same classes are assumed to be compact
>> in the StackInterpreter VM as the CoInterpreter VM.
>>
>>
>>> Thanks.
>>>
>>>
>>
>> HTH
>> --
>> best,
>> Eliot
>>
>>
>>
>
>
> --
> Mariano
> http://marianopeck.wordpress.com
>
>
>


-- 
best,
Eliot
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