* tree-ssa-dse.c (decrement_count): New function.
	(increment_start_addr, maybe_trim_memstar_call): Likewise.
	(dse_dom_walker::optimize_stmt): Call maybe_trim_memstar_call directly
	when we know the partially dead statement is a mem* function.

	* gcc.dg/tree-ssa/ssa-dse-25.c: New test.

From-SVN: r244444