* tree-cfg.c (assert_unreachable_fallthru_edge_p): New function.
	* tree-cfg.h (assert_unreachable_fallthru_edge_p): New prototype.
	* tree-vrp.c (all_imm_uses_in_stmt_or_feed_cond): New function.
	(remove_range_assertions): If ASSERT_EXPR_VAR has no other immediate
	uses but in the condition and ASSERT_EXPR and the other successor of
	the predecessor bb is __builtin_unreachable (), set_range_info of the
	ASSERT_EXPR_VAR to the range info of the ASSERT_EXPR's lhs.

From-SVN: r204255