[Bug sanitizer/110553] New: -fsanitize=undefined needs -latomic on powerpc-unknown-linux-gnu

[Bug sanitizer/110553] New: -fsanitize=undefined needs -latomic on powerpc-unknown-linux-gnu

[sjames at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110553

            Bug ID: 110553
           Summary: -fsanitize=undefined needs -latomic on
                    powerpc-unknown-linux-gnu
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: sanitizer
          Assignee: unassigned at gcc dot gnu.org
          Reporter: sjames at gcc dot gnu.org
                CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
                    jakub at gcc dot gnu.org, kcc at gcc dot gnu.org, marxin at gcc dot gnu.org
  Target Milestone: ---

```
#include <stdio.h>

int main (void) {
    printf("hi\r\n");
}
```

```
$ gcc /tmp/foo.c -o /tmp/foo -fsanitize=undefined
/usr/lib/gcc/powerpc-unknown-linux-gnu/13/../../../../powerpc-unknown-linux-gnu/bin/ld:
/usr/lib/gcc/powerpc-unknown-linux-gnu/13/libubsan.so: undefined reference to
`__atomic_compare_exchange_8'
/usr/lib/gcc/powerpc-unknown-linux-gnu/13/../../../../powerpc-unknown-linux-gnu/bin/ld:
/usr/lib/gcc/powerpc-unknown-linux-gnu/13/libubsan.so: undefined reference to
`__atomic_load_8'
collect2: error: ld returned 1 exit status
```

```
$ gcc /tmp/foo.c -o /tmp/foo -fsanitize=undefined -latomic # works
```

```
$ nm -D /usr/lib/gcc/powerpc-unknown-linux-gnu/13/libubsan.so | grep -i atomic
         U __atomic_compare_exchange_8
         U __atomic_load_8
```

While in this instance I can inject -latomic, it's a pain to try do that for
various configure tests.

[Bug sanitizer/110553] -fsanitize=undefined needs -latomic on powerpc-unknown-linux-gnu

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110553

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I wonder what function uses 64bit values for atomics in ubsan. I only saw 32bit
values (well I saw pointers and size_t in backtrace and 32bit in ubsan).