[Bug rtl-optimization/113551] New: Miscompilation with -O1 -funswitch-loops -fno-strict-overflow

[yshuiv7 at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113551

            Bug ID: 113551
           Summary: Miscompilation with -O1 -funswitch-loops
                    -fno-strict-overflow
           Product: gcc
           Version: 13.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: yshuiv7 at gmail dot com
  Target Milestone: ---

Code:

struct obj {
        int __pad;
        int i;
};

/* aborts when called with NULL */
int assert_not_null(void *); 

void bug(struct obj **root, struct obj *dso) {
        while (1) {
                struct obj *this = *root;

                if (dso == (void *)0)
                        // should return here
                        return;

                if (dso == this)
                        return;

                // shouldn't reach here
                assert_not_null(dso);

                if (!&dso->i)
                        break;
        }
}

// call like this: bug(&obj, NULL);

Result:

* -O1: ok
* -O1 -funswitch-loops: ok
* -O1 -fno-strict-overflow: ok
* -O1 -funswitch-loops -fno-strict-overflow: abort