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#!/usr/bin/env python3
"""
Translate the byte code of a Python function into the corresponding
sequences of C code in CPython's "ceval.c".
"""
from __future__ import print_function, absolute_import
import re
import os.path
from dis import get_instructions # requires Python 3.4+
# collapse some really boring byte codes
_COLLAPSE = {'NOP', 'LOAD_CONST', 'POP_TOP', 'JUMP_FORWARD'}
#_COLLAPSE.clear()
_is_start = re.compile(r"\s* switch \s* \( opcode \)", re.VERBOSE).match
# Py3: TARGET(XX), Py2: case XX
_match_target = re.compile(r"\s* (?: TARGET \s* \( | case \s* ) \s* (\w+) \s* [:)]", re.VERBOSE).match
_ignored = re.compile(r"\s* PREDICTED[A-Z_]*\(", re.VERBOSE).match
_is_end = re.compile(r"\s* } \s* /\* \s* switch \s* \*/", re.VERBOSE).match
_find_pyversion = re.compile(r'\#define \s+ PY_VERSION \s+ "([^"]+)"', re.VERBOSE).findall
class ParseError(Exception):
def __init__(self, message="Failed to parse ceval.c"):
super(ParseError, self).__init__(message)
def parse_ceval(file_path):
snippets = {}
with open(file_path) as f:
lines = iter(f)
for line in lines:
if _is_start(line):
break
else:
raise ParseError()
targets = []
code_lines = []
for line in lines:
target_match = _match_target(line)
if target_match:
if code_lines:
code = ''.join(code_lines).rstrip()
for target in targets:
snippets[target] = code
del code_lines[:], targets[:]
targets.append(target_match.group(1))
elif _ignored(line):
pass
elif _is_end(line):
break
else:
code_lines.append(line)
else:
if not snippets:
raise ParseError()
return snippets
def translate(func, ceval_snippets):
start_offset = 0
code_obj = getattr(func, '__code__', None)
if code_obj and os.path.exists(code_obj.co_filename):
start_offset = code_obj.co_firstlineno
with open(code_obj.co_filename) as f:
code_line_at = {
i: line.strip()
for i, line in enumerate(f, 1)
if line.strip()
}.get
else:
code_line_at = lambda _: None
for instr in get_instructions(func):
code_line = code_line_at(instr.starts_line)
line_no = (instr.starts_line or start_offset) - start_offset
yield line_no, code_line, instr, ceval_snippets.get(instr.opname)
def main():
import sys
import importlib.util
if len(sys.argv) < 3:
print("Usage: %s path/to/Python/ceval.c script.py ..." % sys.argv[0], file=sys.stderr)
return
ceval_source_file = sys.argv[1]
version_header = os.path.join(os.path.dirname(ceval_source_file), '..', 'Include', 'patchlevel.h')
if os.path.exists(version_header):
with open(version_header) as f:
py_version = _find_pyversion(f.read())
if py_version:
py_version = py_version[0]
if not sys.version.startswith(py_version + ' '):
print("Warning: disassembling with Python %s, but ceval.c has version %s" % (
sys.version.split(None, 1)[0],
py_version,
), file=sys.stderr)
snippets = parse_ceval(ceval_source_file)
for code in _COLLAPSE:
if code in snippets:
snippets[code] = ''
for file_path in sys.argv[2:]:
module_name = os.path.basename(file_path)
print("/*######## MODULE %s ########*/" % module_name)
print('')
spec = importlib.util.spec_from_file_location(module_name, file_path)
module = importlib.util.module_from_spec(spec)
spec.loader.exec_module(module)
for func_name, item in sorted(vars(module).items()):
if not callable(item):
continue
print("/* FUNCTION %s */" % func_name)
print("static void") # assuming that it highlights in editors
print("%s() {" % func_name)
last_line = None
for line_no, code_line, instr, snippet in translate(item, snippets):
if last_line != line_no:
if code_line:
print('')
print('/*# %3d %s */' % (line_no, code_line))
print('')
last_line = line_no
print(" %s:%s {%s" % (
instr.opname,
' /* %s */' % instr.argrepr if instr.arg is not None else '',
' /* ??? */' if snippet is None else ' /* ... */ }' if snippet == '' else '',
))
print(snippet or '')
print("} /* FUNCTION %s */" % func_name)
if __name__ == '__main__':
main()
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