[Bug tree-optimization/116409] [15 Regression] Recent phiopt change causing ICE with sqrt and -frounding-math

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116409

--- Comment #8 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Cleaned up testcase from PR116411 :
```
int f (int t, char *a, char *b) {
  if (t)
    return __builtin_strlen (a);
  return __builtin_strlen (b);
}
```