Convert an assembly instruction into its bytecode. It uses gas and otool, so this will only work on OS X, but it'd be pretty easy to modify it for linux.

Instruction2Bytecode.py

# USAGE INSTRUCTIONS 
# It's an interactive shell, where you have the following options...
# - Just type in an assembly instruction in Intel syntax, and it'll spit out the bytecode
# - Change the syntax to AT&T with the att command
# - Change the syntax back to Intel with the intel command
# - Quit with the q command
import os
import sys
import tempfile
import subprocess
import re

intelSyntax = True

def getBytecode(instruction):
	gasCode = ''
	if intelSyntax:
		gasCode = '.globl _start\n\n.text\n.intel_syntax\n_start:\t%s\n' % instruction
	else:
		gasCode = '.globl _start\n\n.text\n_start:\t%s\n' % instruction
	asmFile = open('%s/code.s' % os.getcwd(), 'w')
	asmFile.write(gasCode)
	asmFile.close()

	# assemble the instruction
	gasProcess = subprocess.Popen(['as', '-o', '%s/out.o' % os.getcwd(), '%s/code.s' % os.getcwd()], stderr=subprocess.PIPE)
	gasProcess.wait()
	if len(gasProcess.stderr.read()) != 0:
		print 'Invalid instruction'
		return None

	# get the bytecode from the object file
	otoolProcess = subprocess.Popen(['otool', '-tVj', '%s/out.o' % os.getcwd()], stdout=subprocess.PIPE)
	otoolProcess.wait()

	# delete the files created
	os.remove('%s/code.s' % os.getcwd())
	os.remove('%s/out.o' % os.getcwd())

	# extract the instruction's bytecode from the output
	cocks = re.compile('\d+\s+([0-9a-fA-F]+)')
	matches = cocks.search(otoolProcess.stdout.read())

	if len(matches.groups()) < 1:
		print 'Couldn\'t locate bytecode in otool output'
		return None
	else:
		return matches.groups(1)[0]

sys.stdout.write('>> ')
userInput = raw_input()

while userInput != 'q':
	if userInput == 'intel':
		intelSyntax = True
		print 'Changed to Intel syntax'
	elif userInput == 'att':
		intelSyntax = False
		print 'Changed to AT&T Syntax'
	else:
		bytecode = getBytecode(userInput)
		if bytecode != None:
			print bytecode

	sys.stdout.write('>> ')
	userInput = raw_input()

.text
.file "kernel.c"
.globl kmain // -- Begin function kmain
.p2align 2
.type kmain,@function
kmain: // @kmain
.cfi_startproc
// %bb.0:
sub sp, sp, #16
.cfi_def_cfa_offset 16
mov x8, #32768 // =0x8000
movk x8, #11, lsl #16
str x8, [sp, #8]
ldr x9, [sp, #8]
mov w8, #68 // =0x44
strb w8, [x9]
ldr x9, [sp, #8]
mov w8, #15 // =0xf
strb w8, [x9, #1]
add sp, sp, #16
.cfi_def_cfa_offset 0
ret
.Lfunc_end0:
.size kmain, .Lfunc_end0-kmain
.cfi_endproc
// -- End function
.ident "clang version 17.0.6"
.section ".note.GNU-stack","",@progbits