### 12.3 The compiler ¶

The next stage of the process is the actual compilation of preprocessed source code to assembly language, for a specific processor. The command-line option `-S` instructs `gcc` to convert the preprocessed C source code to assembly language without creating an object file:

    $ gcc -Wall -S hello.i

The resulting assembly language is stored in the file `hello.s`. Here is what the Hello World assembly language for an Intel x86 (i686) processor looks like:

    $ cat hello.s
        .file  "hello.c"
        .section  .rodata
    .LC0:
        .string  "Hello, world!\n"
        .text
    .globl main
        .type  main, @function
    main:
        pushl  %ebp
        movl  %esp, %ebp
        subl  $8, %esp
        andl  $-16, %esp
        movl  $0, %eax
        subl  %eax, %esp
        movl  $.LC0, (%esp)
        call  printf
        movl  $0, %eax
        leave
        ret
        .size  main, .-main
        .ident  "GCC: (GNU) 3.3.1"

Note that the assembly language contains a call to the external function `printf`.