Re: guile 3 update, september edition

[ludo@gnu.org (Ludovic Courtès)]

Hello,

Andy Wingo <wingo@pobox.com> skribis:

> On Mon 17 Sep 2018 11:35, ludo@gnu.org (Ludovic Courtès) writes:
>
>>> The threshold at which Guile will automatically JIT-compile is set from
>>> the GUILE_JIT_THRESHOLD environment variable.  By default it is 50000.
>>> If you set it to -1, you disable the JIT.  If you set it to 0, *all*
>>> code will be JIT-compiled.  The test suite passes at
>>> GUILE_JIT_THRESHOLD=0, indicating that all features in Guile are
>>> supported by the JIT.  Set the GUILE_JIT_LOG environment variable to 1
>>> or 2 to see JIT progress.
>>
>> Just to be clear, does GUILE_JIT_THRESHOLD represents the number of
>> times a given instruction pointer is hit?
>
> No.  It is an abstract "hotness" counter associated with a function's
> code.  (I say "function's code" because many closures can share the same
> code and thus the same counter.  It's not in the scm_tc7_program object
> because some procedures don't have these.)
>
> All counters start at 0 when Guile starts.  A function's counters
> increment by 30 when a function is called, currently, and 2 on every
> loop back-edge.  I have not attempted to tweak these values yet.

OK, I see.

Exciting times!

Ludo’.