* defaults.h (ASM_OUTPUT_ALTERNATE_LABEL_NAME): Provide default.

        * emit-rtl.c (gen_label_rtx): Support LABEL_ALTERNATE_NAME.
        * final.c (final_scan_insn): Emit LABEL_ALTERNATE_NAME.
        * ggc-common.c (ggc_mark_rtx_children): Mark LABEL_ALTERNATE_NAME.
        * jump.c (delete_unreferenced_labels): Don't delete if
        LABEL_ALTERNATE_NAME is set.
        * print-rtl.c (print_rtx): Dump alternate name.
        * rtl.def (CODE_LABEL): Change format to "iuuis00s".
        * rtl.h (LABEL_ALTERNATE_NAME): Define.
        * rtl.texi (LABEL_ALTERNATE_NAME): Document.
        * tm.texi (ASM_OUTPUT_ALTERNATE_LABEL_NAME): Document.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@30382 138bc75d-0d04-0410-961f-82ee72b054a4