re PR target/50358 (AVR: Implement [u]maddqihi4 [u]msubqihi4 patterns on the enhanced core)

	
	PR target/50358
	* config/avr/predicates.md (const_1_to_6_operand): New predicate.
	* config/avr/avr.md: (extend_s): New code attribute.
	(mul_r_d): New code attribute.
	(*maddqihi4, *umaddqihi4): New insns.
	(*msubqihi4, *umsubqihi4): New insns.
	(*usmaddqihi4, *sumaddqihi4): New insns.
	(*usmsubqihi4, *susubdqihi4): New insns.
	(*umaddqihi4.uconst, *maddqihi4.sconst): New insn-and-splits.
	(*umsubqihi4.uconst, *msubqihi4.sconst): New insn-and-splits.
	(*umsubqihi4.uconst.ashift): New insn-and-split.
	(*msubqihi4.sconst.ashift): New insn-and-split.
	(*sumaddqihi4.uconst): New insn-and-split.
	(*sumsubqihi4.uconst): New insn-and-split.
	* config/avr/avr.c (avr_rtx_costs): Report costs of above in case
	PLUS:HI and MINUS:HI.

From-SVN: r178806