[Bug tree-optimization/93767] [8/9/10 Regression] wrong code at -O3 on x86_64-linux-gnu since r8-6064

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93767

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2020-02-17
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |rsandifo at gcc dot gnu.org
            Version|unknown                     |10.0
   Target Milestone|---                         |8.4
            Summary|wrong code at -O3 on        |[8/9/10 Regression] wrong
                   |x86_64-linux-gnu            |code at -O3 on
                   |                            |x86_64-linux-gnu since
                   |                            |r8-6064
     Ever confirmed|0                           |1

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Slightly tweaked, still -O3:
int
main ()
{
  int a[10], b;
  for (b = 6; b >= 3; b--)
    {
      a[b] = 1;
      a[b + 2] = a[3];
    }
  if (a[5] != 1)
    __builtin_abort ();
  return 0;
}
And I can confirm it started with
r8-6064-ga57776a11369621f9e9e8a8a3db6cb406c8bf27b