[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 #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Better and well defined testcase which ICEs:
```
double f(int c, double a, double b) {
  if (c)
    return __builtin_sqrt(a);
  return __builtin_sqrt(b);
}

```