[Vm-dev] Immediates

Bert Freudenberg bert at freudenbergs.de
Thu May 7 17:11:15 UTC 2009


On 07.05.2009, at 18:53, Eliot Miranda wrote:

> On Thu, May 7, 2009 at 9:36 AM, Igor Stasenko <siguctua at gmail.com>  
> wrote:
>
> 2009/5/7 Eliot Miranda <eliot.miranda at gmail.com>:
> >I intend to add immediate characters within the next few months.
> >
> so, does that means that you will extend the oop tag to 2 bits (or  
> more)?
>
> Yes.  Keep 31-bit SmallIntegers, provide e.g. 24-bit immediate  
> characters.  Andreas wrote a thorough sketch of this scheme in 2006.
>
> Or just reserve a non-movable heap space for character objects, like:
> isCharacterObject: oop
>  ^ oop >= charsStart and: [ oop < charsEnd ]
>
> No. This doesn't scale to unicode.  The tagged approach provides  
> much faster string access, and identity comparison for all  
> characters, not just the byte range.

Do we have evidence that Character allocation is an actual performance  
bottleneck?

- Bert -


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