[Vm-dev] Re: Direct object pointers vs indirect ones pros and cons
Javier Burroni
javier.burroni at gmail.com
Wed Oct 26 20:11:53 UTC 2011
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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