[Vm-dev] Cog will require changes to JIT on the next version of Mac

Clément Béra bera.clement at gmail.com
Wed Aug 14 13:14:22 UTC 2019


On Wed, Aug 14, 2019 at 2:32 PM Jan Vrany <jan.vrany at fit.cvut.cz> wrote:

> > 2. Inline cache logic (Mono, closedPIC and openPIC) should be changed
> > not to edit the instructions in the machine code zone but a RW
> > structure (likely execution time overhead induced)
>
> Do you have any performance measurements or references?
>
> I must admit I dislike patching PICs in instruction stream and I
> wonder if it's worth on modern CPUs...
>

No,

I talked with multiple Java/JS VM implementors who said they could not
have a page writable and executable (security policy) so they did not even
try Cog's design.

I think you have to try :-(


> Thanks, Jan
>
>
>

-- 
Clément Béra
https://clementbera.github.io/
https://clementbera.wordpress.com/
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