Brainfuck compiler in Python for x86_64 Linux

bfc.py

#!/usr/bin/env python
# Usage: ./bfc.py source.bf > out.S && as out.S -o out.o && ld out.o

import sys

print("""
    .intel_syntax noprefix
    .global values
    .data
        cells:
          .rept 10000
          .byte 0
          .endr
    .global _start
    .text
    _start:
        lea r15, cells""")

def increment_dp():
    print('inc r15')

def decrement_dp():
    print('dec r15')

def increment():
    print('incb [r15]')

def decrement():
    print('decb [r15]')

def bf_output():
    print("""
		mov rax,1		# write syscall (x86_64)
		mov rdi,1		# fd = stdout
		mov rsi, r15		# *buf = Hello
		mov rdx,1	        # count
		syscall""")

def bf_input():
    print("""
		mov rax,0		# read syscall (x86_64)
		mov rdi,0		# fd = stdin
		mov rsi, r15		# *buf
		mov rdx,1	        # count
		syscall""")

label_stack = []
label_count = 0

def while_open():
    global label_count
    label_stack.append(label_count)
    print("l" + str(label_count) + ":")

    print("""
        cmpb [r15], 0
        je l""" + str(label_count + 1))
    label_count += 2

def while_close():
    l = label_stack.pop()
    print("jmp l" + str(l))
    print("l" + str(l + 1) + ":")

commands = {
    '>': increment_dp,
    '<': decrement_dp,
    '+': increment,
    '-': decrement,
    '.': bf_output,
    ',': bf_input,
    '[': while_open,
    ']': while_close,
}

with open(sys.argv[1], "rt") as in_file:
    for c in in_file.read():
        buf = ""
        if c in commands:
            commands[c]()

print("""
        mov     rax, 60     # system call 60 is exit
        xor     rdi, rdi    # we want return code 0
        syscall""")