* config/avr/predicates.md (const_m255_to_m1_operand): New.
	* config/avr/constraints.md (Cn8, Ca1, Co1, Yx2): New constraints.
	* config/avr/avr.md (add<mode>3) <ALL1>: Make "r,0,r" more
	expensive.
	(*cmphi.zero-extend.0, *cmphi.zero-extend.1)
	(*usum_widenqihi3, *udiff_widenqihi3)
	(*addhi3_zero_extend.const): New combiner insns.
	(andqi3, iorqi3): Provide "l" (NO_LD_REGS) alternative if
	just 1 bit is affected.
	* config/avr/avr.c (avr_out_bitop) <QImode>: Don't access xop[3].
	(avr_out_compare) [EQ,NE]: Tweak comparing d-regs against -1.

From-SVN: r238381