rx.md: Add peepholes and patterns to combine extending loads and simple arithmetic...

rx.md: Add peepholes and patterns to combine extending loads and simple arithmetic...

	* config/rx/rx.md: Add peepholes and patterns to combine
	extending loads and simple arithmetic instructions.
	* config/rx/rx.h (ADJUST_INSN_LENGTH): Define.
        * config/rx/rx-protos.h (rx_adjust_insn_length): Prototype.
        * config/rx/rx.c (rx_is_legitimate_address): Allow QI and HI
	modes to use pre-decrement and post-increment addressing.
        (rx_is_restricted_memory_address): Add range checking of REG+INT
	addresses.
        (rx_print_operand): Add support for %Q.
        Fix handling of %Q.
        (rx_memory_move_cost): Adjust cost of stores.
        (rx_adjust_insn_length): New function.

From-SVN: r171724