Don't take address of ap unless necessary

2015-05-12  Tom de Vries  <tom@codesourcery.com>

	PR tree-optimization/66010
	* gimplify.c (gimplify_modify_expr): Handle new do_deref argument of
	ifn_va_arg.
	* gimplify.h (gimplify_va_arg_internal): Remove loc parameter.
	(gimplify_va_arg_internal): Remove loc parameter.  Assert no array-typed
	va_lists are passed, and remove corresponding handling.
	(gimplify_va_arg_expr): Only take address of ap if necessary.  Add
	do_deref argument to ifn_va_arg.
	* tree-stdarg.c (expand_ifn_va_arg_1): Handle new do_deref argument of
	ifn_va_arg.

	* c-common.c (build_va_arg): Don't mark ap addressable unless necessary.

	* gcc.dg/tree-ssa/stdarg-2.c: Undo scan xfails for f15.

From-SVN: r223054