bug#43725: 28.0.50; Include feature/native-comp into master

[Andrea Corallo via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Andrea Corallo <akrl@sdf.org>
>> Cc: larsi@gnus.org, monnier@iro.umontreal.ca, 43725@debbugs.gnu.org
>> Date: Tue, 09 Mar 2021 19:28:19 +0000
>> 
>> > Looking at a running Emacs, I see that it loads the *.eln files that
>> > are preloaded.  I would expect those to be dumped into the emacs.pdmp
>> > file, as it happens with *.elc files.  If all the stuff is dumped into
>> > emacs.pdmp and loaded from there, why does Emacs still need to load
>> > those *.eln files as shared libraries?
>> 
>> For loaded you mean entering in 'load_comp_unit'?
>
> I looked at the shared libraries loaded by the program as shown by the
> GDB "info sharedlibrary" command.

Okay, that's normal.  The pdumper is dumping only the pseudovector
representing the CU.  When the image is loaded pdumper calls
'load_comp_unit' to have the dynamic linker map again the .eln into
memory.

I think here [1] at the time I wrote something about the reasons why I
ended-up with this solution, but the long story short is that the only
affordable and reliable way to have this job done is to ask the dynamic
linker to do it.

  Andrea

[1] <http://akrl.sdf.org/gccemacs.html#orgc59fae6>