[Bug tree-optimization/86835] [8/9 Regression] Bogus "is used uninitialized" warning with -ffast-math

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86835

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Reduced testcase:
void
foo (int n, double *x, double *y)
{
  int i;
  double b = y[4];
  for (i = 0; i < n; ++i)
    y[3] += __builtin_tanh (x[i] / b);
  y[0] /= b;
  y[1] /= b * b;
  y[2] /= b;
}