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Add advanced source transformations to reduce type checking overhead
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The new 'munge' module performs transformations on the source code.
It uses the AST (abstract syntax tree) representation of Python code
to recognize some idioms such as `if STATIC_TYPING:` and transforms
them into alternatives that have zero overhead in mpy-compiled files
(e.g., `if STATIC_TYPING:` is transformed into `if 0:`, which is eliminated
at compile time due to mpy-cross constant-propagation and dead branch
elimination)

The code assumes the input file is black-formatted. In particular, it
would malfunction if an if-statement and its body are on the same line:
`if STATIC_TYPING: print("boo")` would be incorrectly munged.
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jepler committed Jun 17, 2024
1 parent 1f3c5bd commit 3002d23
Showing 8 changed files with 228 additions and 30 deletions.
2 changes: 2 additions & 0 deletions .github/workflows/build.yml
Original file line number Diff line number Diff line change
@@ -48,6 +48,8 @@ jobs:
git clone --recurse-submodules https://github.com/adafruit/CircuitPython_Community_Bundle.git
cd CircuitPython_Community_Bundle
circuitpython-build-bundles --filename_prefix test-bundle --library_location libraries --library_depth 2
- name: Munge tests
run: pytest
- name: Build Python package
run: |
pip install --upgrade setuptools wheel twine readme_renderer testresources
1 change: 1 addition & 0 deletions .gitignore
Original file line number Diff line number Diff line change
@@ -10,3 +10,4 @@ version.py
.env/*
.DS_Store
.idea/*
testcases/*.out
47 changes: 18 additions & 29 deletions circuitpython_build_tools/build.py
Original file line number Diff line number Diff line change
@@ -36,6 +36,8 @@
import subprocess
import tempfile

from .munge import munge

# pyproject.toml `py_modules` values that are incorrect. These should all have PRs filed!
# and should be removed when the fixed version is incorporated in its respective bundle.

@@ -170,16 +172,6 @@ def mpy_cross(mpy_cross_filename, circuitpython_tag, quiet=False):

shutil.copy("build_deps/circuitpython/mpy-cross/mpy-cross", mpy_cross_filename)

def _munge_to_temp(original_path, temp_file, library_version):
with open(original_path, "r", encoding="utf-8") as original_file:
for line in original_file:
line = line.strip("\n")
if line.startswith("__version__"):
line = line.replace("0.0.0-auto.0", library_version)
line = line.replace("0.0.0+auto.0", library_version)
print(line, file=temp_file)
temp_file.flush()

def get_package_info(library_path, package_folder_prefix):
lib_path = pathlib.Path(library_path)
parent_idx = len(lib_path.parts)
@@ -289,25 +281,22 @@ def library(library_path, output_directory, package_folder_prefix,
full_path = os.path.join(library_path, filename)
output_file = output_directory / filename.relative_to(library_path)
if filename.suffix == ".py":
with tempfile.NamedTemporaryFile(delete=False, mode="w+") as temp_file:
temp_file_name = temp_file.name
try:
_munge_to_temp(full_path, temp_file, library_version)
temp_file.close()
if mpy_cross and os.stat(temp_file.name).st_size != 0:
output_file = output_file.with_suffix(".mpy")
mpy_success = subprocess.call([
mpy_cross,
"-o", output_file,
"-s", str(filename.relative_to(library_path)),
temp_file.name
])
if mpy_success != 0:
raise RuntimeError("mpy-cross failed on", full_path)
else:
shutil.copyfile(temp_file_name, output_file)
finally:
os.remove(temp_file_name)
content = munge(full_path, library_version)
if mpy_cross and content:
# TODO: Once 8.x bundles are no longer built, switch to
# sending mpy-cross the code on stdin instead of via
# temporary file (supports the "-" input argument)
with tempfile.NamedTemporaryFile(delete=False, mode="w+") as temp_file:
temp_file.write(content)
temp_file.flush()
subprocess.check_output([
mpy_cross,
"-o", output_file.with_suffix(".mpy"),
"-s", str(filename.relative_to(library_path)),
temp_file.name
], input=content.encode('utf-8'))
else:
output_file.write_text(content, encoding="utf-8")
else:
shutil.copyfile(full_path, output_file)

117 changes: 117 additions & 0 deletions circuitpython_build_tools/munge.py
Original file line number Diff line number Diff line change
@@ -0,0 +1,117 @@
# The MIT License (MIT)
#
# Copyright (c) 2024 Jeff Epler for Adafruit Industries
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

# Filter program removes some code patterns introduced by type checking,
# to move towards zero overhead static typing in circuitpython libraries
#
# Recognized:
# from __future__ import ... -- eliminated
# try: import typing -- eliminated, but first except: preserved
# try: from typing import ... -- eliminated, but first except: preserved
# if STATIC_TYPING: -- transformed to 'if 0:'
# if sys.implementation_name... -- transformed to unconditional if
# __version__ = ... -- set to library version string
#
# mpy-cross does constant propagation and dead branch elimination of
# 'if 0:' and 'if 1:'
#
# Depends on the file being black-formatted!

import pathlib
import sys
import ast

VERBOSE = 0

# The canonical spelling of this test...
sys_implementation_is_circuitpython = ast.unparse(ast.parse('sys.implementation.name == "circuitpython"'))
sys_implementation_not_circuitpython = ast.unparse(ast.parse('not sys.implementation.name == "circuitpython"'))
sys_implementation_not_circuitpython2 = ast.unparse(ast.parse('sys.implementation.name != "circuitpython"'))

def munge(src: pathlib.Path|str, version_str: str) -> str:
path = pathlib.Path(src)
replacements = {}

def replace(line, new):
if VERBOSE:
replacements[line] = f"{new:<40s} ### {lines[line]}"
else:
replacements[line] = new

def blank_range(node):
for i in range(node.lineno, node.end_lineno+1):
replace(i, "")

def unblank_range(node):
for i in range(node.lineno, node.end_lineno+1):
replacements.pop(i, None)

def imports_from_typing(node):
if isinstance(node, ast.Import) and node.names[0].name == 'typing':
return True
if isinstance(node, ast.ImportFrom) and node.module == 'typing':
return True
return False

def process_statement(node):
# filter out 'from future import...'
if isinstance(node, ast.ImportFrom):
if node.module == '__future__':
blank_range(node)
# filter out 'try: import typing...'
# but preserve the first 'except:' or 'except ImportError'
elif isinstance(node, ast.Try):
b = node.body[0]
if imports_from_typing(node.body[0]):
blank_range(node)
for h in node.handlers:
if h.type is None or ast.unparse(h.type) == 'ImportError' or ast.unparse(h.type) == 'Exception':
unblank_range(h)
replace(h.lineno, 'if 1:')
break
return
elif isinstance(node, ast.If):
node_test = ast.unparse(node.test)
# return the statements in the 'if' branch of 'if sys.implementation...: ...'
if node_test == sys_implementation_is_circuitpython:
replace(node.lineno, 'if 1:')
# return the statements in the 'else' branch of 'if sys.implementation...: ...'
elif node_test == sys_implementation_not_circuitpython or node_test == sys_implementation_not_circuitpython2:
replace(node.lineno, 'if 0:')
# return the statements in the else branch of 'if TYPE_CHECKING: ...'
elif node_test == 'TYPE_CHECKING':
replace(node.lineno, 'if 0:')
elif isinstance(node, ast.Assign) and isinstance(node.targets[0], ast.Name) and node.targets[0].id == '__version__':
replace(node.lineno, f"__version__ = \"{version_str}\"")

content = pathlib.Path(path).read_text(encoding="utf-8")
# Insert a blank line 0 because ast line numbers are 1-based
lines = [''] + content.rstrip().split('\n')
a = ast.parse(content, path.name)

for node in a.body: process_statement(node)

result = []
for i in range(1, len(lines)):
result.append(replacements.get(i, lines[i]))

return "\n".join(result) + "\n"
3 changes: 2 additions & 1 deletion requirements.txt
Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
Click
pytest
requests
semver
wheel
tomli; python_version < "3.11"
wheel
33 changes: 33 additions & 0 deletions testcases/test1.exp
Original file line number Diff line number Diff line change
@@ -0,0 +1,33 @@




if 1:
pass



if 1:
pass




if 1:
pass



if 1:
pass

__version__ = "1.2.3"

if 1:
print("is circuitpython")

if 0:
print("not circuitpython (1)")

if 0:
print("not circuitpython (2)")
33 changes: 33 additions & 0 deletions testcases/test1.py
Original file line number Diff line number Diff line change
@@ -0,0 +1,33 @@
from __future__ import annotation

try:
from typing import TYPE_CHECKING
except ImportError:
pass

try:
from typing import TYPE_CHECKING as T
except ImportError:
pass


try:
import typing
except:
pass

try:
import typing as T
except:
pass

__version__ = "0.0.0-auto"

if sys.implementation.name == "circuitpython":
print("is circuitpython")

if sys.implementation.name != "circuitpython":
print("not circuitpython (1)")

if not sys.implementation.name == "circuitpython":
print("not circuitpython (2)")
22 changes: 22 additions & 0 deletions tests/test_munge.py
Original file line number Diff line number Diff line change
@@ -0,0 +1,22 @@
import sys, pathlib
import pytest

top = pathlib.Path(__file__).parent.parent
sys.path.insert(0, str(top))

from circuitpython_build_tools.munge import munge

@pytest.mark.parametrize("test_path", top.glob("testcases/*.py"))
def test_munge(test_path):
result_path = test_path.with_suffix(".out")
result_path.unlink(missing_ok = True)

result_content = munge(test_path, "1.2.3")
result_path.write_text(result_content, encoding="utf-8")

expected_path = test_path.with_suffix(".exp")
expected_content = expected_path.read_text(encoding="utf-8")

assert result_content == expected_content

result_path.unlink()

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