* tree-ssa-threadedge.c (thread_through_normal_block): New argument VISITED.
        Remove VISISTED as a local variable.  When we have a threadable jump, verify
        the destination of the jump has not been visised.
        (thread_across_edge): Allocate VISITED bitmap once at function scope and
        use it throughout.  Make sure to set appropriate bits in VISITED for E (start
        of jump thread path).

        * tree-ssa-threadupdate.c (mark_threaded_blocks): Reject threading through
        a joiner if any edge on the path has a recorded jump thread.

From-SVN: r203895