https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95722
Bug ID: 95722
Summary: libatomic crashes on __atomic_load of const object
Product: gcc
Version: 10.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: other
Assignee: unassigned at gcc dot gnu.org
Reporter: luis at luismarques dot eu
Target Milestone: ---
With this code in `test.c`:
```
struct S {
int x;
int y;
int z;
};
int main() {
__attribute__((aligned(16))) static const _Atomic struct S a;
struct S b;
b = a;
}
```
On x86_64 I get:
```
$ gcc test.c -latomic && ./a.out
Segmentation fault (core dumped)
```
It crashes on a `lock cmpxchg16b` with the address of `a`, so I imagine the
libatomic implementation is dispatching to an optimized __atomic_load case
where the code assumes it can get a (mutable) lock from the object itself, and
when it tries to acquire that lock it writes to `.rodata`, causing the crash.
