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

[Javier Burroni]

Igor Stasenko wrote:
> 
> the first bench is kind-of 'measure time to access directly to objects'
> the second one is 'measure indirect access'
> and third is measure a loop overhead.
> 
> 

Hi there,
I've just arrived to this thread (thanks to Mariano), and I wanted to share
some speculations: 
Having JIT'ed code with self (the oop of the actual object) in a register,
and selfID (the id of self in the object table) in a second register. 
We have:
accessing ivar: no extra cost
method lookup: 
one extra indirection
sends with MonomorphicInlineCache:
no extra cost if implemented in an instance basis (checking against selfID).
One indirection otherwise

GC (MarkAndCompact):
Faster (due to the removal of the threading process).

saludos
jb


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