[Vm-dev] Direct object pointers vs indirect ones pros and cons

Stefan Marr squeak at stefan-marr.de
Fri Nov 12 09:59:50 UTC 2010

Hi Igor:

On 12 Nov 2010, at 10:32, Igor Stasenko wrote:

> I would like to hear your opinion on that in context: what if you
> would design a VM from scratch,
> and having a direct access to high-optimization compiler/jit. What
> would be your choice?
I don't think you will get a satisfying answer to that question.
It might be that on certain processors the caches are big enough to actually hide the overhead of an object table in such a scenario.

But, by definition, caches are always to small.

I think we have still the source code of David's version of the RoarVM lying around that does not use an object table. With 'a bit of work' it would be possible to measure that overhead for our interpreter for a single core. So, if you feel like it, I could give you a hand here and there ;)

Best regards

Stefan Marr
Software Languages Lab
Vrije Universiteit Brussel
Pleinlaan 2 / B-1050 Brussels / Belgium
Phone: +32 2 629 2974
Fax:   +32 2 629 3525

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