[Bug tree-optimization/80625] New: gcc fails to notice strdup does not modify it's argument

[prathamesh3492 at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80625

            Bug ID: 80625
           Summary: gcc fails to notice strdup does not modify it's
                    argument
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: prathamesh3492 at gcc dot gnu.org
  Target Milestone: ---

Hi,
While working on PR80613, I came up with following test-case:

int f(char *s)
{
  void foo(char *);

  *s = 'a';
  char *p = __builtin_strdup (s);
  foo (p);
  return *s;
}

I assume return *s could be safely replaced by return 97 since strdup will
not modify s ? Or am I mistaken ?

Thanks,
Prathamesh