re PR middle-end/56098 (conditional write through volatile pointer produces unintende...

re PR middle-end/56098 (conditional write through volatile pointer produces unintended read)

	PR tree-optimization/56098
	* tree-ssa-phiopt.c (nt_init_block): Don't call add_or_mark_expr
	for stmts with volatile ops.
	(cond_store_replacement): Don't optimize if assign has volatile ops.
	(cond_if_else_store_replacement_1): Don't optimize if either
	then_assign or else_assign have volatile ops.
	(hoist_adjacent_loads): Don't optimize if either def1 or def2 have
	volatile ops.

	* gcc.dg/pr56098-1.c: New test.
	* gcc.dg/pr56098-2.c: New test.

From-SVN: r195475