[Bug tree-optimization/85315] missed range optimisation opportunity for derefences where index must be 0 or otherwise constrained

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85315

--- Comment #14 from Martin Sebor <msebor at gcc dot gnu.org> ---
Andrew, we discussed the same idea for built-in functions at Couldron.  For
instance, in:

  void f (const char *s, int n)
  {
    char a[8];
    memcpy (a, s, n);     // n must be in [0, 8]
    if (n < 0 || n > 8)   // fold to false
      abort ();
  }