bug#65640: 30.0.50; segfault when building emacs with native-comp

[Andrea Corallo <acorallo@gnu.org>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: StrawberryTea <look@strawberrytea.xyz>
>> Date: Wed, 30 Aug 2023 14:38:55 -0500
>> 
>> 
>> Hi. I just set up a fresh install of Gentoo with Clang as my default
>> compiler. At first, I was trying to compile Emacs with Clang and Emacs
>> was finding -lgccjit but not finding the libgccjit.h header file. So I
>> overwrote the compiler Emacs was using to GCC instead and now it
>> compiles but segfaults when native-compiling some Elisp files.
>> 
>> Build log with Clang (configure error): https://bpa.st/ODFBK
>> Build log with GCC (segfault): https://0x0.st/Hpbz.txt
>
> First, you apply local patches to the Emacs tree, so you are compiling
> code that is not from our Git repository, but some variation of that.
>
> More importantly: it looks like you build Emacs with "-O3 -march=native",
> which are not the default compilation switches, and cause GCC to
> over-optimize the code.  Please try again without those switches.
>
> If using the default compiler switches doesn't help, please run the
> crashing command under GDB, and when it segfaults, produce the
> C-level backtrace and post it here.
>
> Please also always post the build logs as plain text or attachments to
> your messages, instead of pointing to a URL that could some day go
> away, and thus years from now people will be unable to see the log by
> reading this discussion.
>
> Thanks.
>
> P.S. Adding Andrea.

Agree on everything, from this far (and for whatever reason) looks like
the crash is in libgccjit.  So its version might be relevant as well.

Thanks

  Andrea