[Bug tree-optimization/78731] Possible bug with switch when optimization is turned on.

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78731

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 40285
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40285&action=edit
patch

Ah, finally a testcase!  (I have one I can't disclose and thus didn't post the
patch without a good testcase for Jeff to look at)

The issue is that jump threading across backedges may, when following the SSA
value chain, pick up values from a previous iteration.