[ARC] Add support for advanced mpy/mac instructions.

[ARC] Add support for advanced mpy/mac instructions.

gcc/
2017-05-09  Claudiu Zissulescu  <claziss@synopsys.com>

	* config/arc/arc.c (arc_conditional_register_usage): Handle ACCL,
	ACCH registers.
	* config/arc/arc.md (mulsidi3): Use advanced mpy instructions when
	available.
	(umulsidi3): Likewise.
	(mulsidi3_700): Disable this pattern when we have advanced mpy
	instructions.
	(umulsidi3_700): Likewise.
	(maddsidi4): New pattern.
	(macd, mac, mac_r, umaddsidi4, macdu, macu, macu_r): Likewise.
	(mpyd_arcv2hs, mpyd_imm_arcv2hs, mpydu_arcv2hs): Likewise.
	(mpydu_imm_arcv2hs): Likewise.
	* config/arc/predicates.md (accl_operand): New predicate.

From-SVN: r247797