trunc_sp          649 gc/os_dep.c        ptr_t trunc_sp = (ptr_t)((word)sp & ~(GC_page_size - 1));
trunc_sp          650 gc/os_dep.c        word size = GC_get_writable_length(trunc_sp, 0);
trunc_sp          652 gc/os_dep.c        return(trunc_sp + size);