I was wondering how to use GCC on my C source file to dump a mnemonic version of the machine code so I could see what my code was being compiled into. You can do this with J
You can use gdb for this like objdump.
This excerpt is taken from http://sources.redhat.com/gdb/current/onlinedocs/gdb_9.html#SEC64
Here is an example showing mixed source+assembly for Intel x86:
(gdb) disas /m main
Dump of assembler code for function main:
5 {
0x08048330 : push %ebp
0x08048331 : mov %esp,%ebp
0x08048333 : sub $0x8,%esp
0x08048336 : and $0xfffffff0,%esp
0x08048339 : sub $0x10,%esp
6 printf ("Hello.\n");
0x0804833c : movl $0x8048440,(%esp)
0x08048343 : call 0x8048284
7 return 0;
8 }
0x08048348 : mov $0x0,%eax
0x0804834d : leave
0x0804834e : ret
End of assembler dump.