The calling function must not care where the stackpointer is currently pointing.
调用的函数一定不能顾虑栈指针当前所指的位置。
2
This protects against stack, buffer, and functionpointer overflows, all without recompilation.
这样将保护程序代码避免堆栈、缓冲区和函数指针溢出,而且全都不需重新编译。
3
If a function is executing, then the stackpointer is pointing to the top of the whole stack, which is also the top of that function's activation record.