* mn10300.h (REG_CLASS_FROM_LETTER): Map 'y' to SP_REGS.
        Handle 'x' as NO_REGS for this cpu.
        (REGNO_OK_FOR_BIT_BASE_P): Define.
        (REG_OK_FOR_BIT_BASE_P): Define.
        (GO_IF_LEGITIMATE_ADDRESS): Use them.
        (REG_OK_FOR_INDEX_P): Tweak.
        * mn13000.c (REG_SAVE_BYTES): Define.
        (expand_epilogue, initial_offset): Use it.
        (secondary_reload_class): Slightly reformat.
        (output_tst): Tweak comments.
        * mn10300.md: Change 'x' to 'y' for SP_REGS.  Then add 'x' to many
        patterns.
        (addsi3): Turn into a define_expand/define_insn pair.  Rework code for
        three operand addition case to be more efficient.
        (subsi3): Turn into a define_expand/define_insn pair.

From-SVN: r21104