* tree.h (TYPE_ALIGN_OK): New flag.
	* emit-rtl.c (set_mem_attributes): Handle it.
	* expr.c (emit_single_push_insn): Only set to alias set 0 if
	doing sibcall optimization.
	(expand_expr, case COMPONENT_REF): Call set_mem_attributes on case
	when make temporary.
	(expand_expr, case CONVERT_EXPR): Simplify convert-to-union case.
	(expand_expr, case ADDR_EXPR): Abort if TYPE_ALIGN_OK and need copy.

From-SVN: r47149