* flow.c (find_basic_blocks): Remove do_cleanup argument.
Break out that code ...
(cleanup_cfg): ... here.
(commit_one_edge_insertion): Detect a return instruction being
emitted to an edge. Emit a barrier following; clear fallthru.
(commit_edge_insertions): Verify CFG consistency.
* function.c (expand_function_start): Kill unused variable.
(expand_function_end): Likewise.
(thread_prologue_and_epilogue_insns): Use insert_insn_on_edge
to insert the epilogue.
* gcse.c (gcse_main): Adjust for find_basic_blocks change.
(delete_null_pointer_checks): Likewise.
* output.h: Likewise.
* reg-stack.c (reg_to_stack): Likewise.
* toplev.c (rest_of_compilation): Likewise. Run
thread_prologue_and_epilogue_insns after rebuilding the CFG.