2016-10-10  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	PR tree-optimization/77824
	* gimple-ssa-strength-reduction.c (stmt_cost): Explicitly return
	zero cost for copies.
	(find_candidates_dom_walker::before_dom_children): Replace
	MODIFY_EXPR with SSA_NAME.
	(replace_mult_candidate): Likewise.
	(replace_profitable_candidates): Likewise.

From-SVN: r240945