简单的c程序==>机器级代码

/*   code.c  */


int accum = 0;


int sum( int x,int y ){
     int t = x + y;
     accum += t;

     return t;
}

;code.s （部分）

；注意参数x,y的进栈顺序：y 在先，x在后


sum:
    pushl    %ebp
    movl    %esp, %ebp
    movl    12(%ebp), %eax      ； 12(%ebp) ==> y
    addl    8(%ebp), %eax        ; 8(%ebp) ==> x
    addl    %eax, accum
    popl    %ebp
    ret

[heixia@localhost program]$ gcc -O2 -c code.c
[heixia@localhost program]$ gdb code.o
(gdb) x/19xb
0x0 <sum>: 0x55 0x89 0xe5 0x8b 0x45 0x0c 0x03 0x45
0x8 <sum+8>: 0x08 0x01 0x05 0x00 0x00 0x00 0x00 0x5d
0x10 <sum+16>: 0xc3 Cannot access memory at address 0x11

反汇编工具objdump
[heixia@localhost program]$ objdump -d code.o

code.o: file format elf32-i386

Disassembly of section .text:

00000000 <sum>:
   0: 55                    push %ebp
   1: 89 e5                mov %esp,%ebp
   3: 8b 45 0c            mov 0xc(%ebp),%eax
   6: 03 45 08             add 0x8(%ebp),%eax
   9: 01 05 00 00 00 00   add %eax,0x0
   f: 5d                   pop %ebp
  10: c3                   ret