arc: Avoid store/load pipeline hazard

ARC700 targets have a store/load pipeline hazard, if we load within 2
cycles of a store, and the load/store are at the same address, then we
pay a multi-cycle penalty.

This commit avoids this by inserting nop instructions between the store
and the load.

gcc/ChangeLog:

	* config/arc/arc-protos.h (arc_store_addr_hazard_p): Declare.
	* config/arc/arc.c (arc_store_addr_hazard_p): New function.
	(workaround_arc_anomaly): Call arc_store_addr_hazard_p for ARC700.
	* config/arc/arc700.md: Add define_bypass for store/load.

gcc/testsuite/ChangeLog:

	* gcc.target/arc/arc700-stld-hazard.c: New file.

From-SVN: r243007