import marshal
fd = open('path/to/my.pyc', 'rb')
magic = fd.read(4) # 魔术数，与python版本相关
date = fd.read(4) # 编译日期
code_object = marshal.load(fd)
fd.close()

import types
 
def inspect_code_object(co_obj, indent=''):
print indent, "%s(lineno:%d)" % (co_obj.co_name, co_obj.co_firstlineno)
for c in co_obj.co_consts:
if isinstance(c, types.CodeType):
inspect_code_object(c, indent + ' ')
 
inspect_code_object(code_object) # 从第一个对象开始

class A:
def __init__(self):
pass
def __repr__(self):
return 'A()'
a = A()
print a

<module>(lineno:2)
 A(lineno:2)
 __init__(lineno:3)
 __repr__(lineno:5)

co_obj = compile(python_source_code, '<string>', 'exec')

2 0 LOAD_CONST 0 ('A')
 3 LOAD_CONST 3 (())
 6 LOAD_CONST 1 (<code object A at 0x42424242, file "<string>", line 2>)
 9 MAKE_FUNCTION 0
 12 CALL_FUNCTION 0
 15 BUILD_CLASS
 16 STORE_NAME 0 (A)
 
8 19 LOAD_NAME  0 (A)
 22 CALL_FUNCTION 0
 25 STORE_NAME 1 (a)
 
9 28 LOAD_NAME  1 (a)
 31 PRINT_ITEM
 32 PRINT_NEWLINE
 33 LOAD_CONST 2 (None)
 36 RETURN_VALUE

(1) a, b = 1, '2'
(2) a, b = 1, e
(3) a, b, c = 1, 2, e
(4) a, b, c, d = 1, 2, 3, e

0 LOAD_CONST 5 ((1, '2'))
3 UNPACK_SEQUENCE 2
6 STORE_FAST 0 (a)
9 STORE_FAST 1 (b)

12 LOAD_CONST 1 (1)
15 LOAD_GLOBAL 0 (e)
18 ROT_TWO
19 STORE_FAST 0 (a)
22 STORE_FAST 1 (b)

25 LOAD_CONST 1 (1)
28 LOAD_CONST 3 (2)
31 LOAD_GLOBAL 0 (e)
34 ROT_THREE
35 ROT_TWO
36 STORE_FAST 0 (a)
39 STORE_FAST 1 (b)
42 STORE_FAST 2 (c)

45 LOAD_CONST 1 (1)
48 LOAD_CONST 3 (2)
51 LOAD_CONST 4 (3)
54 LOAD_GLOBAL 0 (e)
57 BUILD_TUPLE 4
60 UNPACK_SEQUENCE 4
63 STORE_FAST 0 (a)
66 STORE_FAST 1 (b)
69 STORE_FAST 2 (c)
72 STORE_FAST 3 (d)

func(arg1, arg2, keyword=SOME_VALUE, *unpack_list, **unpack_dict)

0 LOAD_NAME 0 (func)
3 LOAD_NAME 1 (arg1)
6 LOAD_NAME 2 (arg2)
9 LOAD_CONST 0 ('keyword')
12 LOAD_NAME 3 (SOME_VALUE)
15 LOAD_NAME 4 (unpack_list)
18 LOAD_NAME 5 (unpack_dict)
21 CALL_FUNCTION_VAR_KW 258

na = arg & 0xff # num args
nk = (arg >> 8) & 0xff # num keywords
n_to_pop = na + 2 * nk + CALL_EXTRA_ARG_OFFSET[op]

def factorial(n):
if n <= 1:
return 1
elif n == 2:
return 2
return n * factorial(n - 1)

module_co = compile(python_source, '', 'exec')
meth_co = module_co.co_consts[0]

3  0 LOAD_FAST  0 (n)
  3 LOAD_CONST  1 (1)
  6 COMPARE_OP  1 (<=)
  9 POP_JUMP_IF_FALSE 16  <<< control flow
 
4  12 LOAD_CONST  1 (1)
  15 RETURN_VALUE    <<< control flow
 
5 >> 16 LOAD_FAST  0 (n)
  19 LOAD_CONST  2 (2)
  22 COMPARE_OP  2 (==)
  25 POP_JUMP_IF_FALSE 32  <<< control flow
 
6  28 LOAD_CONST  2 (2)
  31 RETURN_VALUE    <<< control flow
 
7 >> 32 LOAD_FAST  0 (n)
  35 LOAD_GLOBAL  0 (factorial)
  38 LOAD_FAST  0 (n)
  41 LOAD_CONST  1 (1)
  44 BINARY_SUBTRACT
  45 CALL_FUNCTION  1
  48 BINARY_MULTIPLY
  49 RETURN_VALUE    <<< control flow

import opcode
RETURN_VALUE = 83
JUMP_FORWARD, JUMP_ABSOLUTE = 110, 113
FALSE_BRANCH_JUMPS = (111, 114) # JUMP_IF_FALSE_OR_POP, POP_JUMP_IF_FALSE
 
def find_blocks(meth_co):
 blocks = {}
 code = meth_co.co_code
 finger_start_block = 0
 i, length = 0, len(code)
 while i < length:
 op = ord(code[i])
 i += 1
 if op == RETURN_VALUE: # We force finishing the block after the return,
    # dead code might still exist after though...
 blocks[finger_start_block] = {
 'length': i - finger_start_block - 1,
 'exit': True
 }
 finger_start_block = i
 elif op >= opcode.HAVE_ARGUMENT:
 oparg = ord(code[i]) + (ord(code[i+1]) << 8)
 i += 2
 if op in opcode.hasjabs: # Absolute jump to oparg
 blocks[finger_start_block] = {
  'length': i - finger_start_block
 }
 if op == JUMP_ABSOLUTE: # Only uncond absolute jump
  blocks[finger_start_block]['conditions'] = {
  'uncond': oparg
  }
 else:
  false_index, true_index = (oparg, i) if op in FALSE_BRANCH_JUMPS else (i, oparg)
  blocks[finger_start_block]['conditions'] = {
  'true': true_index,
  'false': false_index
  }
 finger_start_block = i
 elif op in opcode.hasjrel:
 # Essentially do the same...
 pass
 
 return blocks

Block 0: {'length': 12, 'conditions': {'false': 16, 'true': 12}}
Block 12: {'length': 3, 'exit': True}
Block 16: {'length': 12, 'conditions': {'false': 32, 'true': 28}}
Block 28: {'length': 3, 'exit': True}
Block 32: {'length': 17, 'exit': True}

Basic blocks
 start_block_index :=
 length := size of instructions
 condition := true | false | uncond -> target_index
 exit* := true

def to_dot(blocks):
cache = {}
 
def get_node_id(idx, buf):
if idx not in cache:
cache[idx] = 'node_%d' % idx
buf.append('%s [label="Block Index %d"];' % (cache[idx], idx))
return cache[idx]
 
buffer = ['digraph CFG {']
buffer.append('entry [label="CFG Entry"]; ')
buffer.append('exit [label="CFG Implicit Return"]; ')
 
for block_idx in blocks:
node_id = get_node_id(block_idx, buffer)
if block_idx == 0:
buffer.append('entry -> %s;' % node_id)
if 'conditions' in blocks[block_idx]:
for cond_kind in blocks[block_idx]['conditions']:
target_id = get_node_id(blocks[block_idx]['conditions'][cond_kind], buffer)
buffer.append('%s -> %s [label="%s"];' % (node_id, target_id, cond_kind))
if 'exit' in blocks[block_idx]:
buffer.append('%s -> exit;' % node_id)
 
buffer.append('}')
return 'n'.join(buffer)