cpython/Tools/scripts/deepfreeze.py

"""Deep freeze

The script is executed by _bootstrap_python interpreter. Shared library
extension modules are not available.
"""
import argparse
import ast
import builtins
import collections
import contextlib
import os
import re
import time
import types
from typing import Dict, FrozenSet, TextIO, Tuple

import umarshal

verbose = False


def isprintable(b: bytes) -> bool:
    return all(0x20 <= c < 0x7f for c in b)


def make_string_literal(b: bytes) -> str:
    res = ['"']
    if isprintable(b):
        res.append(b.decode("ascii").replace("\\", "\\\\").replace("\"", "\\\""))
    else:
        for i in b:
            res.append(f"\\x{i:02x}")
    res.append('"')
    return "".join(res)


CO_FAST_LOCAL = 0x20
CO_FAST_CELL = 0x40
CO_FAST_FREE = 0x80


def get_localsplus(code: types.CodeType):
    a = collections.defaultdict(int)
    for name in code.co_varnames:
        a[name] |= CO_FAST_LOCAL
    for name in code.co_cellvars:
        a[name] |= CO_FAST_CELL
    for name in code.co_freevars:
        a[name] |= CO_FAST_FREE
    return tuple(a.keys()), bytes(a.values())


def get_localsplus_counts(code: types.CodeType,
                          names: Tuple[str, ...],
                          kinds: bytes) -> Tuple[int, int, int, int]:
    nlocals = 0
    nplaincellvars = 0
    ncellvars = 0
    nfreevars = 0
    assert len(names) == len(kinds)
    for name, kind in zip(names, kinds):
        if kind & CO_FAST_LOCAL:
            nlocals += 1
            if kind & CO_FAST_CELL:
                ncellvars += 1
        elif kind & CO_FAST_CELL:
            ncellvars += 1
            nplaincellvars += 1
        elif kind & CO_FAST_FREE:
            nfreevars += 1
    assert nlocals == len(code.co_varnames) == code.co_nlocals, \
        (nlocals, len(code.co_varnames), code.co_nlocals)
    assert ncellvars == len(code.co_cellvars)
    assert nfreevars == len(code.co_freevars)
    assert len(names) == nlocals + nplaincellvars + nfreevars
    return nlocals, nplaincellvars, ncellvars, nfreevars


PyUnicode_1BYTE_KIND = 1
PyUnicode_2BYTE_KIND = 2
PyUnicode_4BYTE_KIND = 4


def analyze_character_width(s: str) -> Tuple[int, bool]:
    maxchar = ' '
    for c in s:
        maxchar = max(maxchar, c)
    ascii = False
    if maxchar <= '\xFF':
        kind = PyUnicode_1BYTE_KIND
        ascii = maxchar <= '\x7F'
    elif maxchar <= '\uFFFF':
        kind = PyUnicode_2BYTE_KIND
    else:
        kind = PyUnicode_4BYTE_KIND
    return kind, ascii


def removesuffix(base: str, suffix: str) -> str:
    if base.endswith(suffix):
        return base[:len(base) - len(suffix)]
    return base

class Printer:

    def __init__(self, file: TextIO) -> None:
        self.level = 0
        self.file = file
        self.cache: Dict[tuple[type, object, str], str] = {}
        self.hits, self.misses = 0, 0
        self.patchups: list[str] = []
        self.write('#include "Python.h"')
        self.write('#include "internal/pycore_gc.h"')
        self.write('#include "internal/pycore_code.h"')
        self.write('#include "internal/pycore_long.h"')
        self.write("")

    @contextlib.contextmanager
    def indent(self) -> None:
        save_level = self.level
        try:
            self.level += 1
            yield
        finally:
            self.level = save_level

    def write(self, arg: str) -> None:
        self.file.writelines(("    "*self.level, arg, "\n"))

    @contextlib.contextmanager
    def block(self, prefix: str, suffix: str = "") -> None:
        self.write(prefix + " {")
        with self.indent():
            yield
        self.write("}" + suffix)

    def object_head(self, typename: str) -> None:
        with self.block(".ob_base =", ","):
            self.write(f".ob_refcnt = 999999999,")
            self.write(f".ob_type = &{typename},")

    def object_var_head(self, typename: str, size: int) -> None:
        with self.block(".ob_base =", ","):
            self.object_head(typename)
            self.write(f".ob_size = {size},")

    def field(self, obj: object, name: str) -> None:
        self.write(f".{name} = {getattr(obj, name)},")

    def generate_bytes(self, name: str, b: bytes) -> str:
        if b == b"":
            return "(PyObject *)&_Py_SINGLETON(bytes_empty)"
        self.write("static")
        with self.indent():
            with self.block("struct"):
                self.write("PyObject_VAR_HEAD")
                self.write("Py_hash_t ob_shash;")
                self.write(f"char ob_sval[{len(b) + 1}];")
        with self.block(f"{name} =", ";"):
            self.object_var_head("PyBytes_Type", len(b))
            self.write(".ob_shash = -1,")
            self.write(f".ob_sval = {make_string_literal(b)},")
        return f"& {name}.ob_base.ob_base"

    def generate_unicode(self, name: str, s: str) -> str:
        kind, ascii = analyze_character_width(s)
        if kind == PyUnicode_1BYTE_KIND:
            datatype = "uint8_t"
        elif kind == PyUnicode_2BYTE_KIND:
            datatype = "uint16_t"
        else:
            datatype = "uint32_t"
        self.write("static")
        with self.indent():
            with self.block("struct"):
                if ascii:
                    self.write("PyASCIIObject _ascii;")
                else:
                    self.write("PyCompactUnicodeObject _compact;")
                self.write(f"{datatype} _data[{len(s)+1}];")
        with self.block(f"{name} =", ";"):
            if ascii:
                with self.block("._ascii =", ","):
                    self.object_head("PyUnicode_Type")
                    self.write(f".length = {len(s)},")
                    self.write(".hash = -1,")
                    with self.block(".state =", ","):
                        self.write(".kind = 1,")
                        self.write(".compact = 1,")
                        self.write(".ascii = 1,")
                        self.write(".ready = 1,")
                self.write(f"._data = {make_string_literal(s.encode('ascii'))},")
                return f"& {name}._ascii.ob_base"
            else:
                with self.block("._compact =", ","):
                    with self.block("._base =", ","):
                        self.object_head("PyUnicode_Type")
                        self.write(f".length = {len(s)},")
                        self.write(".hash = -1,")
                        with self.block(".state =", ","):
                            self.write(f".kind = {kind},")
                            self.write(".compact = 1,")
                            self.write(".ascii = 0,")
                            self.write(".ready = 1,")
                with self.block(f"._data =", ","):
                    for i in range(0, len(s), 16):
                        data = s[i:i+16]
                        self.write(", ".join(map(str, map(ord, data))) + ",")
                if kind == PyUnicode_2BYTE_KIND:
                    self.patchups.append("if (sizeof(wchar_t) == 2) {")
                    self.patchups.append(f"    {name}._compact._base.wstr = (wchar_t *) {name}._data;")
                    self.patchups.append(f"    {name}._compact.wstr_length = {len(s)};")
                    self.patchups.append("}")
                if kind == PyUnicode_4BYTE_KIND:
                    self.patchups.append("if (sizeof(wchar_t) == 4) {")
                    self.patchups.append(f"    {name}._compact._base.wstr = (wchar_t *) {name}._data;")
                    self.patchups.append(f"    {name}._compact.wstr_length = {len(s)};")
                    self.patchups.append("}")
                return f"& {name}._compact._base.ob_base"


    def generate_code(self, name: str, code: types.CodeType) -> str:
        # The ordering here matches PyCode_NewWithPosOnlyArgs()
        # (but see below).
        co_code = self.generate(name + "_code", code.co_code)
        co_consts = self.generate(name + "_consts", code.co_consts)
        co_names = self.generate(name + "_names", code.co_names)
        co_varnames = self.generate(name + "_varnames", code.co_varnames)
        co_freevars = self.generate(name + "_freevars", code.co_freevars)
        co_cellvars = self.generate(name + "_cellvars", code.co_cellvars)
        co_filename = self.generate(name + "_filename", code.co_filename)
        co_name = self.generate(name + "_name", code.co_name)
        co_qualname = self.generate(name + "_qualname", code.co_qualname)
        co_linetable = self.generate(name + "_linetable", code.co_linetable)
        co_endlinetable = self.generate(name + "_endlinetable", code.co_endlinetable)
        co_columntable = self.generate(name + "_columntable", code.co_columntable)
        co_exceptiontable = self.generate(name + "_exceptiontable", code.co_exceptiontable)
        # These fields are not directly accessible
        localsplusnames, localspluskinds = get_localsplus(code)
        co_localsplusnames = self.generate(name + "_localsplusnames", localsplusnames)
        co_localspluskinds = self.generate(name + "_localspluskinds", localspluskinds)
        # Derived values
        nlocals, nplaincellvars, ncellvars, nfreevars = \
            get_localsplus_counts(code, localsplusnames, localspluskinds)
        with self.block(f"static struct PyCodeObject {name} =", ";"):
            self.object_head("PyCode_Type")
            # But the ordering here must match that in cpython/code.h
            # (which is a pain because we tend to reorder those for perf)
            # otherwise MSVC doesn't like it.
            self.write(f".co_consts = {co_consts},")
            self.write(f".co_names = {co_names},")
            self.write(f".co_firstinstr = (_Py_CODEUNIT *) {removesuffix(co_code, '.ob_base.ob_base')}.ob_sval,")
            self.write(f".co_exceptiontable = {co_exceptiontable},")
            self.field(code, "co_flags")
            self.write(".co_warmup = QUICKENING_INITIAL_WARMUP_VALUE,")
            self.field(code, "co_argcount")
            self.field(code, "co_posonlyargcount")
            self.field(code, "co_kwonlyargcount")
            self.field(code, "co_stacksize")
            self.field(code, "co_firstlineno")
            self.write(f".co_code = {co_code},")
            self.write(f".co_localsplusnames = {co_localsplusnames},")
            self.write(f".co_localspluskinds = {co_localspluskinds},")
            self.write(f".co_filename = {co_filename},")
            self.write(f".co_name = {co_name},")
            self.write(f".co_qualname = {co_qualname},")
            self.write(f".co_linetable = {co_linetable},")
            self.write(f".co_endlinetable = {co_endlinetable},")
            self.write(f".co_columntable = {co_columntable},")
            self.write(f".co_nlocalsplus = {len(localsplusnames)},")
            self.field(code, "co_nlocals")
            self.write(f".co_nplaincellvars = {nplaincellvars},")
            self.write(f".co_ncellvars = {ncellvars},")
            self.write(f".co_nfreevars = {nfreevars},")
            self.write(f".co_varnames = {co_varnames},")
            self.write(f".co_cellvars = {co_cellvars},")
            self.write(f".co_freevars = {co_freevars},")
        return f"& {name}.ob_base"

    def generate_tuple(self, name: str, t: Tuple[object, ...]) -> str:
        items = [self.generate(f"{name}_{i}", it) for i, it in enumerate(t)]
        self.write("static")
        with self.indent():
            with self.block("struct"):
                self.write("PyGC_Head _gc_head;")
                with self.block("struct", "_object;"):
                    self.write("PyObject_VAR_HEAD")
                    if t:
                        self.write(f"PyObject *ob_item[{len(t)}];")
        with self.block(f"{name} =", ";"):
            with self.block("._object =", ","):
                self.object_var_head("PyTuple_Type", len(t))
                if items:
                    with self.block(f".ob_item =", ","):
                        for item in items:
                            self.write(item + ",")
        return f"& {name}._object.ob_base.ob_base"

    def _generate_int_for_bits(self, name: str, i: int, digit: int) -> None:
        sign = -1 if i < 0 else 0 if i == 0 else +1
        i = abs(i)
        digits: list[int] = []
        while i:
            i, rem = divmod(i, digit)
            digits.append(rem)
        self.write("static")
        with self.indent():
            with self.block("struct"):
                self.write("PyObject_VAR_HEAD")
                self.write(f"digit ob_digit[{max(1, len(digits))}];")
        with self.block(f"{name} =", ";"):
            self.object_var_head("PyLong_Type", sign*len(digits))
            if digits:
                ds = ", ".join(map(str, digits))
                self.write(f".ob_digit = {{ {ds} }},")

    def generate_int(self, name: str, i: int) -> str:
        if -5 <= i <= 256:
            return f"(PyObject *)&_PyLong_SMALL_INTS[_PY_NSMALLNEGINTS + {i}]"
        if abs(i) < 2**15:
            self._generate_int_for_bits(name, i, 2**15)
        else:
            connective = "if"
            for bits_in_digit in 15, 30:
                self.write(f"#{connective} PYLONG_BITS_IN_DIGIT == {bits_in_digit}")
                self._generate_int_for_bits(name, i, 2**bits_in_digit)
                connective = "elif"
            self.write("#else")
            self.write('#error "PYLONG_BITS_IN_DIGIT should be 15 or 30"')
            self.write("#endif")
            # If neither clause applies, it won't compile
        return f"& {name}.ob_base.ob_base"

    def generate_float(self, name: str, x: float) -> str:
        with self.block(f"static PyFloatObject {name} =", ";"):
            self.object_head("PyFloat_Type")
            self.write(f".ob_fval = {x},")
        return f"&{name}.ob_base"

    def generate_complex(self, name: str, z: complex) -> str:
        with self.block(f"static PyComplexObject {name} =", ";"):
            self.object_head("PyComplex_Type")
            self.write(f".cval = {{ {z.real}, {z.imag} }},")
        return f"&{name}.ob_base"

    def generate_frozenset(self, name: str, fs: FrozenSet[object]) -> str:
        ret = self.generate_tuple(name, tuple(sorted(fs)))
        self.write("// TODO: The above tuple should be a frozenset")
        return ret

    def generate_file(self, module: str, code: object)-> None:
        module = module.replace(".", "_")
        self.generate(f"{module}_toplevel", code)
        with self.block(f"static void {module}_do_patchups(void)"):
            for p in self.patchups:
                self.write(p)
        self.patchups.clear()
        self.write(EPILOGUE.replace("%%NAME%%", module))

    def generate(self, name: str, obj: object) -> str:
        # Use repr() in the key to distinguish -0.0 from +0.0
        key = (type(obj), obj, repr(obj))
        if key in self.cache:
            self.hits += 1
            # print(f"Cache hit {key!r:.40}: {self.cache[key]!r:.40}")
            return self.cache[key]
        self.misses += 1
        if isinstance(obj, (types.CodeType, umarshal.Code)) :
            val = self.generate_code(name, obj)
        elif isinstance(obj, tuple):
            val = self.generate_tuple(name, obj)
        elif isinstance(obj, str):
            val = self.generate_unicode(name, obj)
        elif isinstance(obj, bytes):
            val = self.generate_bytes(name, obj)
        elif obj is True:
            return "Py_True"
        elif obj is False:
            return "Py_False"
        elif isinstance(obj, int):
            val = self.generate_int(name, obj)
        elif isinstance(obj, float):
            val = self.generate_float(name, obj)
        elif isinstance(obj, complex):
            val = self.generate_complex(name, obj)
        elif isinstance(obj, frozenset):
            val = self.generate_frozenset(name, obj)
        elif obj is builtins.Ellipsis:
            return "Py_Ellipsis"
        elif obj is None:
            return "Py_None"
        else:
            raise TypeError(
                f"Cannot generate code for {type(obj).__name__} object")
        # print(f"Cache store {key!r:.40}: {val!r:.40}")
        self.cache[key] = val
        return val


EPILOGUE = """
PyObject *
_Py_get_%%NAME%%_toplevel(void)
{
    %%NAME%%_do_patchups();
    return (PyObject *) &%%NAME%%_toplevel;
}
"""

FROZEN_COMMENT_C = "/* Auto-generated by Programs/_freeze_module.c */"
FROZEN_COMMENT_PY = "/* Auto-generated by Programs/_freeze_module.py */"

FROZEN_DATA_LINE = r"\s*(\d+,\s*)+\s*"


def is_frozen_header(source: str) -> bool:
    return source.startswith((FROZEN_COMMENT_C, FROZEN_COMMENT_PY))


def decode_frozen_data(source: str) -> types.CodeType:
    lines = source.splitlines()
    while lines and re.match(FROZEN_DATA_LINE, lines[0]) is None:
        del lines[0]
    while lines and re.match(FROZEN_DATA_LINE, lines[-1]) is None:
        del lines[-1]
    values: Tuple[int, ...] = ast.literal_eval("".join(lines).strip())
    data = bytes(values)
    return umarshal.loads(data)


def generate(args: list[str], output: TextIO) -> None:
    printer = Printer(output)
    for arg in args:
        file, modname = arg.rsplit(':', 1)
        with open(file, "r", encoding="utf8") as fd:
            source = fd.read()
            if is_frozen_header(source):
                code = decode_frozen_data(source)
            else:
                code = compile(fd.read(), f"<frozen {modname}>", "exec")
            printer.generate_file(modname, code)
    if verbose:
        print(f"Cache hits: {printer.hits}, misses: {printer.misses}")


parser = argparse.ArgumentParser()
parser.add_argument("-o", "--output", help="Defaults to deepfreeze.c", default="deepfreeze.c")
parser.add_argument("-v", "--verbose", action="store_true", help="Print diagnostics")
parser.add_argument('args', nargs="+", help="Input file and module name (required) in file:modname format")

@contextlib.contextmanager
def report_time(label: str):
    t0 = time.time()
    try:
        yield
    finally:
        t1 = time.time()
    if verbose:
        print(f"{label}: {t1-t0:.3f} sec")


def main() -> None:
    global verbose
    args = parser.parse_args()
    verbose = args.verbose
    output = args.output
    with open(output, "w", encoding="utf-8") as file:
        with report_time("generate"):
            generate(args.args, file)
    if verbose:
        print(f"Wrote {os.path.getsize(output)} bytes to {output}")


if __name__ == "__main__":
    main()