A number of places in the code base (notably ceval.c and frameobject.c) rely on mapping variable names to indices in the frame "locals plus" array (AKA fast locals), and thus opargs. Currently the compiler indirectly encodes that information on the code object as the tuples co_varnames, co_cellvars, and co_freevars. At runtime the dependent code must calculate the proper mapping from those, which isn't ideal and impacts performance-sensitive sections. This is something we can easily address in the compiler instead.
This change addresses the situation by replacing internal use of co_varnames, etc. with a single combined tuple of names in locals-plus order, along with a minimal array mapping each to its kind (local vs. cell vs. free). These two new PyCodeObject fields, co_fastlocalnames and co_fastllocalkinds, are not exposed to Python code for now, but co_varnames, etc. are still available with the same values as before (though computed lazily).
Aside from the (mild) performance impact, there are a number of other benefits:
* there's now a clear, direct relationship between locals-plus and variables
* code that relies on the locals-plus-to-name mapping is simpler
* marshaled code objects are smaller and serialize/de-serialize faster
Also note that we can take this approach further by expanding the possible values in co_fastlocalkinds to include specific argument types (e.g. positional-only, kwargs). Doing so would allow further speed-ups in _PyEval_MakeFrameVector(), which is where args get unpacked into the locals-plus array. It would also allow us to shrink marshaled code objects even further.
https://bugs.python.org/issue43693
Fix a crash at Python exit when a deallocator function removes the
last strong reference to a heap type.
Don't read type memory after calling basedealloc() since
basedealloc() can deallocate the type and free its memory.
_PyMem_IsPtrFreed() argument is now constant.
* Remove 'zombie' frames. We won't need them once we are allocating fixed-size frames.
* Add co_nlocalplus field to code object to avoid recomputing size of locals + frees + cells.
* Move locals, cells and freevars out of frame object into separate memory buffer.
* Use per-threadstate allocated memory chunks for local variables.
* Move globals and builtins from frame object to per-thread stack.
* Move (slow) locals frame object to per-thread stack.
* Move internal frame functions to internal header.
* Add Py_TPFLAGS_SEQUENCE and Py_TPFLAGS_MAPPING, add to all relevant standard builtin classes.
* Set relevant flags on collections.abc.Sequence and Mapping.
* Use flags in MATCH_SEQUENCE and MATCH_MAPPING opcodes.
* Inherit Py_TPFLAGS_SEQUENCE and Py_TPFLAGS_MAPPING.
* Add NEWS
* Remove interpreter-state map_abc and seq_abc fields.
Faster bz2/lzma/zlib via new output buffering.
Also adds .readall() function to _compression.DecompressReader class
to take best advantage of this in the consume-all-output at once scenario.
Often a 5-20% speedup in common scenarios due to less data copying.
Contributed by Ma Lin.
To improve the user experience understanding what part of the error messages associated with SyntaxErrors is wrong, we can highlight the whole error range and not only place the caret at the first character. In this way:
>>> foo(x, z for z in range(10), t, w)
File "<stdin>", line 1
foo(x, z for z in range(10), t, w)
^
SyntaxError: Generator expression must be parenthesized
becomes
>>> foo(x, z for z in range(10), t, w)
File "<stdin>", line 1
foo(x, z for z in range(10), t, w)
^^^^^^^^^^^^^^^^^^^^
SyntaxError: Generator expression must be parenthesized
Add pycore_moduleobject.h internal header file with static inline
functions to access module members:
* _PyModule_GetDict()
* _PyModule_GetDef()
* _PyModule_GetState()
These functions don't check at runtime if their argument has a valid
type and can be inlined even if Python is not built with LTO.
_PyType_GetModuleByDef() uses _PyModule_GetDef().
Replace PyModule_GetState() with _PyModule_GetState() in the
extension modules, considered as performance sensitive:
* _abc
* _functools
* _operator
* _pickle
* _queue
* _random
* _sre
* _struct
* _thread
* _winapi
* array
* posix
The following extensions are now built with the Py_BUILD_CORE_MODULE
macro defined, to be able to use the internal pycore_moduleobject.h
header: _abc, array, _operator, _queue, _sre, _struct.
When printing AttributeError, PyErr_Display will offer suggestions of similar
attribute names in the object that the exception was raised from:
>>> collections.namedtoplo
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: module 'collections' has no attribute 'namedtoplo'. Did you mean: namedtuple?
* Remove redundant tracing_possible field from interpreter state.
* Move 'use_tracing' from tstate onto C stack, for fastest possible checking in dispatch logic.
* Add comments stressing the importance stack discipline when dealing with CFrames.
* Add NEWS
* Split PyType_Ready() into sub-functions.
* type_ready_mro() now checks if bases are static types earlier.
* Check tp_name earlier, in type_ready_checks().
* Add _PyType_IsReady() macro to check if a type is ready.
* Add source location attributes to alias.
* Move alias star construction to pegen helper.
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
Rename AST functions of pycore_ast.h to use the "_PyAST_" prefix.
Remove macros creating aliases without prefix. For example, Module()
becomes _PyAST_Module(). Update Grammar/python.gram to use
_PyAST_xxx() functions.
* pycore_ast.h no longer defines the Yield macro.
* Fix a compiler warning on Windows: "warning C4005: 'Yield': macro
redefinition".
* Python-ast.c now defines directly functions with their real
_Py_xxx() name, rather than xxx().
* Remove "#undef Yield" in C files including pycore_ast.h.
Reorganize pycore_interp_init() to initialize singletons before the
the first PyType_Ready() call. Fix an issue when Python is configured
using --without-doc-strings.
See [PEP 597](https://www.python.org/dev/peps/pep-0597/).
* Add `-X warn_default_encoding` and `PYTHONWARNDEFAULTENCODING`.
* Add EncodingWarning
* Add io.text_encoding()
* open(), TextIOWrapper() emits EncodingWarning when encoding is omitted and warn_default_encoding is enabled.
* _pyio.TextIOWrapper() uses UTF-8 as fallback default encoding used when failed to import locale module. (used during building Python)
* bz2, configparser, gzip, lzma, pathlib, tempfile modules use io.text_encoding().
* What's new entry
Remove the pyarena.h header file with functions:
* PyArena_New()
* PyArena_Free()
* PyArena_Malloc()
* PyArena_AddPyObject()
These functions were undocumented, excluded from the limited C API,
and were only used internally by the compiler.
Add pycore_pyarena.h header. Rename functions:
* PyArena_New() => _PyArena_New()
* PyArena_Free() => _PyArena_Free()
* PyArena_Malloc() => _PyArena_Malloc()
* PyArena_AddPyObject() => _PyArena_AddPyObject()
Remove parser functions using the "struct _mod" type, because the
AST C API was removed:
* PyParser_ASTFromFile()
* PyParser_ASTFromFileObject()
* PyParser_ASTFromFilename()
* PyParser_ASTFromString()
* PyParser_ASTFromStringObject()
These functions were undocumented and excluded from the limited C
API.
Add pycore_parser.h internal header file. Rename functions:
* PyParser_ASTFromFileObject() => _PyParser_ASTFromFile()
* PyParser_ASTFromStringObject() => _PyParser_ASTFromString()
These functions are no longer exported (replace PyAPI_FUNC() with
extern).
Remove also _PyPegen_run_parser_from_file() function. Update
test_peg_generator to use _PyPegen_run_parser_from_file_pointer()
instead.
Remove the compiler functions using "struct _mod" type, because the
public AST C API was removed:
* PyAST_Compile()
* PyAST_CompileEx()
* PyAST_CompileObject()
* PyFuture_FromAST()
* PyFuture_FromASTObject()
These functions were undocumented and excluded from the limited C API.
Rename functions:
* PyAST_CompileObject() => _PyAST_Compile()
* PyFuture_FromASTObject() => _PyFuture_FromAST()
Moreover, _PyFuture_FromAST() is no longer exported (replace
PyAPI_FUNC() with extern). _PyAST_Compile() remains exported for
test_peg_generator.
Remove also compatibility functions:
* PyAST_Compile()
* PyAST_CompileEx()
* PyFuture_FromAST()
These functions were undocumented and excluded from the limited C
API.
Most names defined by these header files were not prefixed by "Py"
and so could create names conflicts. For example, Python-ast.h
defined a "Yield" macro which was conflict with the "Yield" name used
by the Windows <winbase.h> header.
Use the Python ast module instead.
* Move Include/asdl.h to Include/internal/pycore_asdl.h.
* Move Include/Python-ast.h to Include/internal/pycore_ast.h.
* Remove ast.h header file.
* pycore_symtable.h no longer includes Python-ast.h.
Rename Include/symtable.h to to Include/internal/pycore_symtable.h,
don't export symbols anymore (replace PyAPI_FUNC and PyAPI_DATA with
extern) and rename functions:
* PyST_GetScope() to _PyST_GetScope()
* PySymtable_BuildObject() to _PySymtable_Build()
* PySymtable_Free() to _PySymtable_Free()
Remove PySymtable_Build(), Py_SymtableString() and
Py_SymtableStringObject() functions.
The Py_SymtableString() function was part the stable ABI by mistake
but it could not be used, since the symtable.h header file was
excluded from the limited C API.
The Python symtable module remains available and is unchanged.
Remove the PyAST_Validate() function. It is no longer possible to
build a AST object (mod_ty type) with the public C API. The function
was already excluded from the limited C API (PEP 384).
Rename PyAST_Validate() function to _PyAST_Validate(), move it to the
internal C API, and don't export it anymore (replace PyAPI_FUNC with
extern).
The function was added in bpo-12575 by
the commit 832bfe2ebd.
Move _PyAST_GetDocString() and _PyAST_ExprAsUnicode() functions the
internal C API: from Include/ast.h to a new
Include/internal/pycore_ast.h header file. Don't export these
functions anymore: replace PyAPI_FUNC() with extern.
Remove also unused includes.
At Python startup, call _PyGILState_Init() before
PyInterpreterState_New() which calls _PyThreadState_GET(). When
Python is built using --with-experimental-isolated-subinterpreters,
_PyThreadState_GET() uses autoTSSkey.
The types.FunctionType constructor now inherits the current builtins
if the globals dictionary has no "__builtins__" key, rather than
using {"None": None} as builtins: same behavior as eval() and exec()
functions.
Defining a function with "def function(...): ..." in Python is not
affected, globals cannot be overriden with this syntax: it also
inherits the current builtins.
PyFrame_New(), PyEval_EvalCode(), PyEval_EvalCodeEx(),
PyFunction_New() and PyFunction_NewWithQualName() now inherits the
current builtins namespace if the globals dictionary has no
"__builtins__" key.
* Add _PyEval_GetBuiltins() function.
* _PyEval_BuiltinsFromGlobals() now uses _PyEval_GetBuiltins() if
builtins cannot be found in globals.
* Add tstate parameter to _PyEval_BuiltinsFromGlobals().
Pass the current interpreter (interp) rather than the current Python
thread state (tstate) to internal functions which only use the
interpreter.
Modified functions:
* _PyXXX_Fini() and _PyXXX_ClearFreeList() functions
* _PyEval_SignalAsyncExc(), make_pending_calls()
* _PySys_GetObject(), sys_set_object(), sys_set_object_id(), sys_set_object_str()
* should_audit(), set_flags_from_config(), make_flags()
* _PyAtExit_Call()
* init_stdio_encoding()
* etc.
Replace _PyThreadState_GET() with _PyInterpreterState_GET() in
functions which only need the current interpreter, but don't need the
current Python thread state.
Replace also _PyThreadState_UncheckedGet() with _PyThreadState_GET()
in faulthandler.c, since _PyThreadState_UncheckedGet() is just an
alias to _PyThreadState_GET() in practice.
* Refactor _PyFrame_New_NoTrack() and PyFunction_NewWithQualName()
code.
* PyFrame_New() checks for _PyEval_BuiltinsFromGlobals() failure.
* Fix a ref leak in _PyEval_BuiltinsFromGlobals() error path.
* Complete PyFunction_GetModule() documentation: it returns a
borrowed reference and it can return NULL.
* Move _PyEval_BuiltinsFromGlobals() definition to the internal C
API.
* PyFunction_NewWithQualName() uses _Py_IDENTIFIER() API for the
"__name__" string to make it compatible with subinterpreters.
* Further refactoring of PyEval_EvalCode and friends. Break into make-frame, and eval-frame parts.
* Simplify function vector call using new _PyEval_Vector.
* Remove unused internal functions: _PyEval_EvalCodeWithName and _PyEval_EvalCode.
* Don't use legacy function PyEval_EvalCodeEx.
* bpo-42979: Enhance abstract.c assertions checking slot result
Add _Py_CheckSlotResult() function which fails with a fatal error if
a slot function succeeded with an exception set or failed with no
exception set: write the slot name, the type name and the current
exception (if an exception is set).
The Py_FatalError() function and the faulthandler module now dump the
list of extension modules on a fatal error.
Add _Py_DumpExtensionModules() and _PyModule_IsExtension() internal
functions.
