* langhooks.h (struct lang_hooks): Add new field deep_unsharing.
	* langhooks-def.h (LANG_HOOKS_DEEP_UNSHARING): New macro.
	(LANG_HOOKS_INITIALIZER): Add LANG_HOOKS_DEEP_UNSHARING.
	* gimplify.c: (mostly_copy_tree_r): Copy trees under SAVE_EXPR and
	TARGET_EXPR nodes, but only once, if instructed to do so.  Do not
	propagate the 'data' argument to copy_tree_r.
	(copy_if_shared_r): Remove bogus ATTRIBUTE_UNUSED marker.
	Propagate 'data' argument to walk_tree.
	(copy_if_shared): New function.
	(unmark_visited_r): Remove bogus ATTRIBUTE_UNUSED marker.
	(unmark_visited): New function.
	(unshare_body): Call copy_if_shared instead of doing it manually.
	(unvisit_body): Call unmark_visited instead of doing it manually.
ada/
	* gcc-interface/misc.c (LANG_HOOKS_DEEP_UNSHARING): Redefine.
	* gcc-interface/trans.c (unshare_save_expr): Delete.
	(gigi): Do not unshare trees under SAVE_EXPRs here.

From-SVN: r159592