Backport expcnt patches.

Backport expcnt patches.

2019-09-05  Andrew Stubbs  <ams@codesourcery.com>

	Backport from mainline:

	2019-07-31  Andrew Stubbs  <ams@codesourcery.com>

	gcc/
	* config/gcn/gcn-valu.md
	(scatter<mode>_insn_1offset<exec_scatter>): Remove s_waitcnt.
	(scatter<mode>_insn_1offset_ds<exec_scatter>): Likewise.
	(scatter<mode>_insn_2offsets<exec_scatter>): Likewise.
	* config/gcn/gcn.c (gcn_md_reorg): Add delayeduse and reads to
	struct ilist. Add nops for delayeduse insns.
	* config/gcn/gcn.md (delayeduse): New attribute.
	(*movbi): Remove s_waitcnt from stores.
	(*mov<mode>_insn): Likewise.
	(*movti_insn): Likewise. Add delayeduse attribute.
	(sync_compare_and_swap<mode>_insn): Add delayeduse attribute.
	(atomic_store<mode>): Remove or adjust s_waitcnt.

	2019-09-05  Andrew Stubbs  <ams@codesourcery.com>

	gcc/
	* config/gcn/gcn.md (*movti_insn): Set delayeduse for global_store.
	(sync_compare_and_swap<mode>_insn): Likewise.

(cherry picked from openacc-gcc-9-branch commit
cb61e528165ad4e88fef1fc787f1a16b591b2fca)