* cgraph.c (cgraph_make_edge, dump_cgraph_node, cgraph_set_call_stmt):
	Set nothrow flag.
	* cgraph.h (struct function): Reduce loop_nest to 30 bits; add
	can_throw_external flag.
	* ipa-reference.c (ipa_utils_reduced_inorder): Update call.
	* ipa-pure-const.c (ignore_edge): New function.
	(propagate): Compute order for NOTHROW computation; set NOTHROWs
	only over can_throw_external edges.
	(local_pure_const): Add nothrow flag.
	* ipa-utils.c (searchc): Add ignore_edge callback.
	(ipa_utils_reduced_inorder): Add ignore_edge callback.
	* ipa-utils.h (ipa_utils_reduced_inorder): Update prototype.
	(set_nothrow_function_flags): Update cgraph.
	* tree-cfg.c (verify_stmt): Relax nothrow checking when in IPA mode.

From-SVN: r146322