[Bug tree-optimization/100053] tree-fre incorrectly delete a condition

["rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100053

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
It would be nice if the reduced testcase could be sanitized to throw less
diagnostics with -Wall, likewise if it were a runtime testcase.

Reduced:

int __attribute__((returns_twice,noipa)) x() { return 0; }
void __attribute__((noipa)) ar() {}
void __attribute__((noipa)) as() { __builtin_abort (); }
int a1, a2, a3;
void __attribute__((noipa)) v(int init)
{ 
  if (!init) {
    as();
    if (a1)
      goto aq;
    if (x ())
      if (a2)
        as();
  }
  if (!init)
    a3 = 1;
  ar();
aq:
  if (!init)
    as();
}

int main()
{
  v(1);
  return 0;
}