# === original files
$ ls
 4 diary.txt   4 main.c

# compile with options
#   -save-temps   keep intermediate files
#                   .i  text after preprocessor
#                   .s  text after assembler
#                   .o  binary after compiler (before linking)
#   -m32          generate I32 assembly (as used in textbook)
#   -O0           no opimization (so assembly matches C)
#   -g            include C symbol names for use in gdb 
$ gcc -save-temps -g -m32 -O0 main.c -o main

# === dump binary to assembly ; then look at ext file main.dump
$ objdump -d -g main > main.dump
 4 diary.txt  12 main*  4 main.c  12 main.dump   4 main.i   4 main.o   8 main.s

# === run program with gdb and examine it there.
$ gdb main
(gdb) start
Temporary breakpoint 1 at 0x80483f3: file main.c, line 15.
Starting program: .../main 

Temporary breakpoint 1, main () at main.c:15
15        int a = 1;
(gdb) info frame
Stack level 0, frame at 0xbffff840:
 eip = 0x80483f3 in main (main.c:15); saved eip 0xb7e88bd6
 source language c.
 Arglist at 0xbffff838, args: 
 Locals at 0xbffff838, Previous frame's sp is 0xbffff840
 Saved registers:
  ebp at 0xbffff838, eip at 0xbffff83c
(gdb) info registers
eax            0xbffff8e4       -1073743644
ecx            0x497c7d03       1232895235
edx            0x1      1
ebx            0xb7fc6ff4       -1208193036
esp            0xbffff820       0xbffff820
ebp            0xbffff838       0xbffff838
esi            0x0      0
edi            0x0      0
eip            0x80483f3        0x80483f3 <main+6>
eflags         0x200282 [ SF IF ID ]
cs             0x73     115
ss             0x7b     123
ds             0x7b     123
es             0x7b     123
fs             0x0      0
gs             0x33     51
(gdb) list
10        *i = *j;
11        *j = temp;
12      }
13      
14      int main(){
15        int a = 1;
16        int b = 2;
17        int c;
18        swap(&a, &b);
19        c = sum(a,b);
(gdb) disass sum
Dump of assembler code for function sum:
   0x080483b4 <+0>:     push   %ebp
   0x080483b5 <+1>:     mov    %esp,%ebp
   0x080483b7 <+3>:     sub    $0x10,%esp
   0x080483ba <+6>:     mov    0xc(%ebp),%eax
   0x080483bd <+9>:     mov    0x8(%ebp),%edx
   0x080483c0 <+12>:    lea    (%edx,%eax,1),%eax
   0x080483c3 <+15>:    mov    %eax,-0x4(%ebp)
   0x080483c6 <+18>:    mov    -0x4(%ebp),%eax
   0x080483c9 <+21>:    leave  
   0x080483ca <+22>:    ret    
End of assembler dump.
(gdb)