https://github.com/python/cpython/commit/57c9810ba4a157f9f608e5b36dcb8a3dfa1628a2
commit: 57c9810ba4a157f9f608e5b36dcb8a3dfa1628a2
branch: main
author: Brandt Bucher <[email protected]>
committer: brandtbucher <[email protected]>
date: 2025-05-05T20:06:41-07:00
summary:
GH-113464: Add the JIT to What's New (GH-133486)
files:
M Doc/using/configure.rst
M Doc/whatsnew/3.14.rst
M Tools/jit/README.md
diff --git a/Doc/using/configure.rst b/Doc/using/configure.rst
index 3d3776acbc7bea..b914d3397b6dda 100644
--- a/Doc/using/configure.rst
+++ b/Doc/using/configure.rst
@@ -302,14 +302,21 @@ General Options
.. option:: --enable-experimental-jit=[no|yes|yes-off|interpreter]
- Indicate how to integrate the :ref:`JIT compiler
<whatsnew313-jit-compiler>`.
-
- * ``no`` - build the interpreter without the JIT.
- * ``yes`` - build the interpreter with the JIT.
- * ``yes-off`` - build the interpreter with the JIT but disable it by
default.
- * ``interpreter`` - build the interpreter without the JIT, but with the
tier 2 enabled interpreter.
-
- By convention, ``--enable-experimental-jit`` is a shorthand for
``--enable-experimental-jit=yes``.
+ Indicate how to integrate the :ref:`experimental just-in-time compiler
<whatsnew314-jit-compiler>`.
+
+ * ``no``: Don't build the JIT.
+ * ``yes``: Enable the JIT. To disable it at runtime, set the environment
+ variable :envvar:`PYTHON_JIT=0 <PYTHON_JIT>`.
+ * ``yes-off``: Build the JIT, but disable it by default. To enable it at
+ runtime, set the environment variable :envvar:`PYTHON_JIT=1 <PYTHON_JIT>`.
+ * ``interpreter``: Enable the "JIT interpreter" (only useful for those
+ debugging the JIT itself). To disable it at runtime, set the environment
+ variable :envvar:`PYTHON_JIT=0 <PYTHON_JIT>`.
+
+ ``--enable-experimental-jit=no`` is the default behavior if the option is
not
+ provided, and ``--enable-experimental-jit`` is shorthand for
+ ``--enable-experimental-jit=yes``. See :file:`Tools/jit/README.md` for more
+ information, including how to install the necessary build-time dependencies.
.. note::
diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst
index a345687813f16b..8f427fff76b0ba 100644
--- a/Doc/whatsnew/3.14.rst
+++ b/Doc/whatsnew/3.14.rst
@@ -77,6 +77,7 @@ Summary -- release highlights
:ref:`argparse <whatsnew314-color-argparse>`,
:ref:`json <whatsnew314-color-json>` and
:ref:`calendar <whatsnew314-color-calendar>` CLIs
+* :ref:`Binary releases for the experimental just-in-time compiler
<whatsnew314-jit-compiler>`
Incompatible changes
@@ -715,6 +716,36 @@ in the :envvar:`PYTHONSTARTUP` script.
(Contributed by Łukasz Langa in :gh:`131507`.)
+.. _whatsnew314-jit-compiler:
+
+Binary releases for the experimental just-in-time compiler
+----------------------------------------------------------
+
+The official macOS and Windows release binaries now include an *experimental*
+just-in-time (JIT) compiler. Although it is **not** recommended for production
+use, it can be tested by setting :envvar:`PYTHON_JIT=1 <PYTHON_JIT>` as an
+environment variable. Downstream source builds and redistributors can use the
+:option:`--enable-experimental-jit=yes-off` configuration option for similar
+behavior.
+
+The JIT is at an early stage and still in active development. As such, the
+typical performance impact of enabling it can range from 10% slower to 20%
+faster, depending on workload. To aid in testing and evaluation, a set of
+introspection functions has been provided in the :data:`sys._jit` namespace.
+:func:`sys._jit.is_available` can be used to determine if the current
executable
+supports JIT compilation, while :func:`sys._jit.is_enabled` can be used to tell
+if JIT compilation has been enabled for the current process.
+
+Currently, the most significant missing functionality is that native debuggers
+and profilers like ``gdb`` and ``perf`` are unable to unwind through JIT frames
+(Python debuggers and profilers, like :mod:`pdb` or :mod:`profile`, continue to
+work without modification). Free-threaded builds do not support JIT
compilation.
+
+Please report any bugs or major performance regressions that you encounter!
+
+.. seealso:: :pep:`744`
+
+
Other language changes
======================
diff --git a/Tools/jit/README.md b/Tools/jit/README.md
index ff4b3964e65bad..8e817574b4d72b 100644
--- a/Tools/jit/README.md
+++ b/Tools/jit/README.md
@@ -54,13 +54,13 @@ choco install llvm --version=19.1.0
## Building
-For `PCbuild`-based builds, pass the new `--experimental-jit` option to
`build.bat`.
+For `PCbuild`-based builds, pass the `--experimental-jit` option to
`build.bat`.
-For all other builds, pass the new `--enable-experimental-jit` option to
`configure`.
+For all other builds, pass the `--enable-experimental-jit` option to
`configure`.
Otherwise, just configure and build as you normally would. Cross-compiling
"just works", since the JIT is built for the host platform.
-The JIT can also be enabled or disabled using the `PYTHON_JIT` environment
variable, even on builds where it is enabled or disabled by default. More
details about configuring CPython with the JIT and optional values for
`--enable-experimental-jit` can be found
[here](https://docs.python.org/dev/whatsnew/3.13.html#experimental-jit-compiler).
+The JIT can also be enabled or disabled using the `PYTHON_JIT` environment
variable, even on builds where it is enabled or disabled by default. More
details about configuring CPython with the JIT and optional values for
`--enable-experimental-jit` can be found
[here](https://docs.python.org/dev/using/configure.html#cmdoption-enable-experimental-jit).
[^pep-744]: [PEP 744](https://peps.python.org/pep-0744/)
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