* toplev.c (no_new_pseudos): Define.
        (rest_of_compilation):  Set no_new_pseudos as needed.
        * emit-rtl.c (gen_reg_rtx): Abort if we try to create a new pseudo
        if no_new_pseudos is set.
        * rtl.h (no_new_pseudos): Declare it.
        * reload1.c (reload): Update comments.
        * md.texi: Corresponding changes.
        * reload1.c (reg_used_in_insn): Renamed from reg_used_by_pseudo.
        (choose_reload_regs): Rename it here as well.  When computing it,
        also merge in used hardregs.

From-SVN: r23855