* function.c (keep_stack_depressed): Major rework.
	(handle_epilogue_set, emit_equiv_load): New functions.
	(thread_prologue_and_epilogue_insns): keep_stack_depressed now
	has return value.
	* jump.c (returnjump_p_1): Also return 1 if SET with SET_IS_RETURN_P.
	* rtl.h (SET_IS_RETURN_P): New macro.

From-SVN: r47250