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From: "wilco at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/110773] [Aarch64] crash (SIGBUS) due to atomic
 instructions on under-aligned memory
Date: Thu, 04 Apr 2024 10:59:56 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D110773

--- Comment #4 from Wilco <wilco at gcc dot gnu.org> ---
(In reply to Sainan from comment #3)
> I seem to be having a related issue, although in my case the struct looks
> like this:
>=20
> template <typename T>
> struct Data
> {
>     T* data;
>     std::atomic_uint count;
>     bool flag;
> };
>=20
> And it's crashing on `--count;`
>=20
> Surely this is not a user issue in this case because the pointer should
> always be 8 bytes, so count should be evenly aligned on a 8-byte boundary.
> (Unless the atomic operation needs 16-byte alignment?)

The atomic will also set correct struct alignment.

> Same code also runs fine when compiled via MSVC and run on Windows, altho=
ugh
> it's unclear if this might simply be my Linux test machine running an old=
er
> ARM CPU compared to my Windows on ARM test machine.

You would get a crash if you build for LSE so you get a LDADDAL instruction=
 and
then run it on a CPU that doesn't. So try -mcpu=3Dnative and it should work=
.=