* basic-block.h (rediscover_loops_after_threading): Declare.
        * tree-ssa-dom.c: Include cfgloop.h.
        (tree_ssa_dominator_optimize): Discover loops and some basic
        properties.  Remove forwarder blocks recreated by loop header
        canonicalization.  Also mark backedges in the CFG.
        * tree-ssa-threadupdate.c: Include cfgloop.h
        (rediscover_loops_after_threading): Define.
        (struct local_info): New field, JUMP_THREADED.
        (prune_undesirable_thread_requests): New function.
        (redirect_edges): Clear EDGE_ABNORMAL.  If edges were threaded
        then record that fact for the callers of redirct_edges.
        (thread_block): If BB has incoming backedges, then call
        prune_undesirable_thraed_requests.    Note when we are
        going to have to rediscover loop information.  Return a
        boolean indicating if any jumps were threaded.
        (thread_through_all_blocks): Bubble up boolean indicating
        if any jumps were threaded.
        * Makefile.in (tree-ssa-dom.o): Depend on cfgloop.h
        (tree-ssa-threadupdate.o): Similarly.

From-SVN: r95903