Turn c into assembly


Turn c code into assembly language with gcc.


Create a hello.c file with the following contents or any other c program to convert into assembly language:

#include <stdio.h>

void main () {
	printf("Hello world!\n");

Generate the assembly output:

jemurray@shell:~$ gcc -S hello.c
jemurray@shell:~$ ls -al hell*
-rw-r--r-- 1 jemurray jemurray  64 Mar  9 19:59 hello.c
-rw-r--r-- 1 jemurray jemurray 438 Mar  9 19:59 hello.s

Examine the assembly code:

jemurray@shell:~$ cat hello.s
	.file	"hello.c"
	.section	.rodata
	.string	"Hello world!"
	.globl	main
	.type	main, @function
	pushq	%rbp
	.cfi_def_cfa_offset 16
	.cfi_offset 6, -16
	movq	%rsp, %rbp
	.cfi_def_cfa_register 6
	leaq	.LC0(%rip), %rdi
	call	puts@PLT
	popq	%rbp
	.cfi_def_cfa 7, 8
	.size	main, .-main
	.ident	"GCC: (Debian 8.3.0-6) 8.3.0"
	.section	.note.GNU-stack,"",@progbits

Why would non-low level programmers care? Because it’s interesting to understand the dark magic wizards use to speak with the processors or at least as close as us mere mortals can understand. But seriously, most people would not write assembly code like gcc generates. However, it is still fun to see the individual instruction opcodes the processor executes to print a single line of text.