[Bug tree-optimization/65177] [5 Regression]: extend jump thread for finite state automata causes miscompilation

[law at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65177

--- Comment #8 from Jeffrey A. Law <law at redhat dot com> ---
There's not enough information in those comments to definitively say the SEME
copier isn't updating the SSA graph properly.  If I were looking at this, I'd
want the dump as we enter VRP or DOM (whichever is triggering the problematic
FSM thread), then a dump after that pass was done.  Preferably the dumps would
include the basic block information (-fdump-tree-<whatever>-blocks).  Knowing
the shape of the CFG is critical to proving or disproving the SEME copier is
mucking things up.