bug#71292: 30.0.50; macOS: .elns have no debug info

[Gerd Möllmann]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Gerd Möllmann <gerd.moellmann@gmail.com>
>> Cc: 71292@debbugs.gnu.org
>> Date: Sat, 01 Jun 2024 08:15:39 +0200
>> 
>> When debugging a native-compiled function (speed = 1) an macOS/arm64, I
>> find that the debug info that libgccjit 14.1 generates is apparently
>> incorrect.
>> 
>> For example, I see car_safe being called with some argument, but when I
>> look in the caller in the generated C file and print what it purportedly
>> passes as an argumebnt, it's something completely different.
>
> This should be reported to the GCC and libgccjit folks.  The most
> probable cause is incorrect DWARF debug info emitted by the compiler.
> Alternatively, it could be that LLDB interprets the debug info
> incorrectly.  I sometimes see similar problems when debugging Emacs,
> especially in optimized versions: arguments in function calls are
> shown in reverse order, which of course is bogus, since the code
> works as expected.

After reading the GCC "how to report a bug" advice, I don't think I can
produce something useful for them in any reasonable time frame.

The jit people will also not be of great help I'm afraid. There seems to
be no one in the know using macOS :-).

But there have been some arm64 related commits in GCC during the last
weeks, so there's hope.

BTW, I'm now using the attached change in my Emacs, which allows me to
set native-comp-debug, -speed, and -driver-options via environment
variables. Maybe that's something for Andrea (CC'd).

0001-Allow-overriding-comp-settings-for-speed-debug-drive.patch
Description: comp settings