[Bug tree-optimization/94734] [10 Regression] Program crashes when compiled with -O2 since r10-1892-gb9ef6a2e04bfd013

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94734

--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Yeah.
add_or_mark_expr could be extended to handle more complex addresses (perhaps
get_inner_reference and hash on the decl + offset expression and taking into
account the bitpos/bitsize then?

Further testcase.  Both foo and bar are miscompiled, baz is fine because arr[7]
is known to be always within the object bounds.

__attribute__((noipa)) int
foo (int n)
{
  int arr[16], s = 0;
  for (int i = 0; i < n; i++)
    {
      if (i < 16)
        arr[i] = i;
    }
  for (int i = 0; i < 16; i++)
    s += arr[i];
  return s;
}

__attribute__((noipa)) int
bar (int n, int x, unsigned long y, unsigned long z)
{
  int arr[16], s = 0;
  arr[4] = 42;
  for (int i = 0; i < n; i++)
    {
      if (x == (i & 0x25))
        arr[y] = i;
    }
  return arr[z];
}

__attribute__((noipa)) int
baz (int n, int x, unsigned long z)
{
  int arr[16], s = 0;
  arr[12] = 42;
  for (int i = 0; i < n; i++)
    {
      if (x == (i & 0x25))
        arr[7] = i;
    }
  return arr[z];
}

int
main ()
{
  if (foo (10374) != 15 * 16 / 2)
    __builtin_abort ();
  if (bar (25, 0x25, (unsigned long) 0xdeadbeefbeefdeadULL, 4) != 42)
    __builtin_abort ();
  if (bar (25, 4, 17, 17) != 22)
    __builtin_abort ();
  if (baz (25, 0x25, 12) != 42)
    __builtin_abort ();
  if (baz (25, 4, 7) != 22)
    __builtin_abort ();
  if (baz (25, 4, 12) != 42)
    __builtin_abort ();
  return 0;
}