函数调用时入栈参数与局部变量在栈中地址问题

Dinghow9 2017-04-10 07:02:35

#include <iostream>



int foo(int a, int b, int c, int d) {

  int e;

  int f;

  std::cout << std::hex;

  std::cout << "a = " << a << std::endl;

  std::cout << "Address of a: " << &a << std::endl;

  std::cout << "Address of b: " << &b << std::endl;

  std::cout << "Address of c: " << &c << std::endl;

  std::cout << "Address of d: " << &d << std::endl;

  std::cout << "Address of e: " << &e << std::endl;

  std::cout << "Address of f: " << &f << std::endl;

  // a 参数控制递归调用次数

  if (a != 0) {

    foo(a - 1, b, c, d);

  }

  return a + b + c + d;

} 



int main() {

  // 进行 4 次嵌套的函数调用

  foo(4, 2, 3, 4);

  return 0;

}

源码如上，运行结果
gcc 4.9.2 -32bit release:
a = 4
Address of a: 0x6efea0
Address of b: 0x6efea4
Address of c: 0x6efea8
Address of d: 0x6efeac
Address of e: 0x6efe8c
Address of f: 0x6efe88
a = 1
Address of a: 0x6efe70
Address of b: 0x6efe74
Address of c: 0x6efe78
Address of d: 0x6efe7c
Address of e: 0x6efe5c
Address of f: 0x6efe58
a = 2
Address of a: 0x6efe40
Address of b: 0x6efe44
Address of c: 0x6efe48
Address of d: 0x6efe4c
Address of e: 0x6efe2c
Address of f: 0x6efe28
a = 1
Address of a: 0x6efe10
Address of b: 0x6efe14
Address of c: 0x6efe18
Address of d: 0x6efe1c
Address of e: 0x6efdfc
Address of f: 0x6efdf8
a = 0
Address of a: 0x6efde0
Address of b: 0x6efde4
Address of c: 0x6efde8
Address of d: 0x6efdec
Address of e: 0x6efdcc
Address of f: 0x6efdc8
gcc 4.9.2 -64bit release:
a = 4
Address of a: 0x70fe30
Address of b: 0x70fe38
Address of c: 0x70fe40
Address of d: 0x70fe48
Address of e: 0x70fe0c
Address of f: 0x70fe08
a = 3
Address of a: 0x70fde0
Address of b: 0x70fde8
Address of c: 0x70fdf0
Address of d: 0x70fdf8
Address of e: 0x70fdbc
Address of f: 0x70fdb8
a = 2
Address of a: 0x70fd90
Address of b: 0x70fd98
Address of c: 0x70fda0
Address of d: 0x70fda8
Address of e: 0x70fd6c
Address of f: 0x70fd68
a = 1
Address of a: 0x70fd40
Address of b: 0x70fd48
Address of c: 0x70fd50
Address of d: 0x70fd58
Address of e: 0x70fd1c
Address of f: 0x70fd18
a = 0
Address of a: 0x70fcf0
Address of b: 0x70fcf8
Address of c: 0x70fd00
Address of d: 0x70fd08
Address of e: 0x70fccc
Address of f: 0x70fcc8
而就我目前的知识了解，栈是从高地址到底地址存储数据，而读取参数的顺序为从右到左，以第一次函数调用为例，入栈顺序应该是：d-c-b-a之后是按顺序将局部变量入栈，即e-f，但是比较e和f的地址可以发现二者在32位下相差14个字节，在64位下相差36个字节，感到比较奇怪，按之前看到的文章：http://blog.csdn.net/tdgx2004/article/details/5985531，在局部变量与参数之间应该是函数地址与保护栈底（32位下8个字节），但是实际情况是14个字节，非常好奇还有6个字节装的是什么？
求教大神们。

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