[Bug middle-end/80775] [8 Regression] -O3 produces ice in group_case_labels_stmt

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80775

Peter Bergner <bergner at gcc dot gnu.org> changed:

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

--- Comment #8 from Peter Bergner <bergner at gcc dot gnu.org> ---
I'm testing a patch.  The special thing here, is that we try combining multiple
case statements that lead to the same block and that block contains a
__builtin_unreachable() call.  If we remove the edge//block for the first case
label, that causes a problem for the next case label that points to the same
block.

My "fix" is to first merge the case statements and then check whether the
resulting case label points to an unreachable block and delete it if it does,
which fixes the ICE.