GC_RETURN_ADDR    468 gc/include/gc.h #   define GC_RETURN_ADDR (GC_word)__return_address
GC_RETURN_ADDR    505 gc/include/gc.h #   define GC_RETURN_ADDR (GC_word)__builtin_return_address(0)
GC_RETURN_ADDR    508 gc/include/gc.h #   define GC_RETURN_ADDR 0