[Bug middle-end/89008] [7/8 Regression] O2 and O1 results differ for simple test

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89008

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2
             Status|UNCONFIRMED                 |NEW
      Known to work|                            |6.4.0, 9.0
           Keywords|                            |needs-bisection, wrong-code
   Last reconfirmed|                            |2019-01-23
                 CC|                            |marxin at gcc dot gnu.org
     Ever confirmed|0                           |1
            Summary|O2 and O1 results differ    |[7/8 Regression] O2 and O1
                   |for simple test             |results differ for simple
                   |                            |test
   Target Milestone|---                         |7.5
      Known to fail|                            |7.4.0, 8.2.0

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.  Seems to work on trunk, disabling SLSR fixes it.  We end up with

f ()
{
  <bb 2> [local count: 14598063]:
  b = 0;
  c = 4;
  e = 6;
  d = 6;
  a = 4294967292;
  return 0;

so I guess a fix needs backporting.  Martin, can you bisect the fix?