bug#69480: Emacs Lisp needs, for its great 'native-compile', 'declare' and 'the' for fixnums and arrays.

[Stephen Berman]

On Fri, 01 Mar 2024 14:45:39 +0200 Eli Zaretskii <eliz@gnu.org> wrote:

>> From: Stephen Berman <stephen.berman@gmx.net>
>> Cc: Stephen Berman via "Bug reports for GNU Emacs, the Swiss army knife of
>>  text editors" <bug-gnu-emacs@gnu.org>,  Eli Zaretskii <eliz@gnu.org>,
>>   Robert Boyer <robertstephenboyer@gmail.com>,  69480@debbugs.gnu.org
>> Date: Fri, 01 Mar 2024 13:33:56 +0100
>>
>> On Fri, 01 Mar 2024 07:18:29 -0500 Andrea Corallo <acorallo@gnu.org> wrote:
>>
>> >> Why is the timing with native compilation so much slower than with byte
>> >> compilation?
>> >
>> > Because the file is not lexically scoped so we are not running
>> > optimizations.
>>
>> Ah, ok.
>>
>> > On my laptop I see:
>> >
>> > 11 secs byte compiled
>> > 18 secs native compiled
>> >
>> > 7 secs byte compiled with lexical scope
>> > 5 secs  native compiled with lexical scope.
>>
>> I got these timings with lexical scope:
>>
>> native compiled: (12.717023709000001 1 0.34653286699999997)
>>   byte compiled: (9.597325325 1 0.38987931)
>>
>> It's still slower with native compilation than with byte compilation on
>> my machine, unlike on yours.  Do you have any idea why?
>
> Maybe your system takes time to allocate memory?  This program
> allocates almost 850MB of memory on my system, so maybe yours starts
> paging?

I see a similar allocation, but I have 16 GB of RAM (~12 of which were
free when I ran the benchmark), so I think that shouldn't be an issue.

> Anyway, profiling could give some hints.

That says almost all memory and CPU are consumed by `build-sieve':

    807,918,497  99% - command-execute
    806,047,846  99%  - funcall-interactively
    804,440,179  99%   - eval-expression
    804,440,179  99%    - #<compiled -0x5db3e1955cb81d1>
    804,440,179  99%     - #<compiled -0x88d7268f58840fe>
    804,440,179  99%      - eval
    804,440,179  99%       - progn
    800,000,184  99%        - benchmark-call
    800,000,104  99%         - #<lambda 0x8b1d56ce50812>
    800,000,104  99%          - build-sieve
             40   0%             expt
             80   0%           time-since
      4,439,995   0%        + emacs-lisp-native-compile-and-load
      1,607,667   0%   + execute-extended-command
      1,870,651   0%  + byte-code
         99,848   0% + redisplay_internal (C function)
          1,729   0%   Automatic GC
          1,416   0% + timer-event-handler
          1,180   0% + ...

But I don't see how that bears on the difference between native and byte
compilation in my timings versus yours and Andrea's.

Steve Berman