Building PyPy from Source
=========================

For building PyPy, we recommend installing a pre-built PyPy first (see
:doc:`install`). It is possible to build PyPy with CPython, but it will take a
lot longer to run -- depending on your architecture, between two and three
times as long.

Even when using PyPy to build PyPy, translation is time-consuming -- 30
minutes on a fast machine -- and RAM-hungry.  You will need **at least** 2 GB
of memory on a 32-bit machine and 4GB on a 64-bit machine.


Clone the repository
--------------------

If you prefer to compile your own PyPy, or if you want to modify it, you
will need to obtain a copy of the sources.  This can be done either by
`downloading them from the download page`_ or by checking them out from the
repository using mercurial.  We suggest using mercurial if you want to access
the current development.

.. _downloading them from the download page: http://pypy.org/download.html

You must issue the following command on your
command line, DOS box, or terminal::

    hg clone http://bitbucket.org/pypy/pypy pypy

This will clone the repository and place it into a directory
named ``pypy``, and will get you the PyPy source in ``pypy/pypy`` and
documentation files in ``pypy/pypy/doc``.
We try to ensure that the tip is always stable, but it might
occasionally be broken.  You may want to check out `our nightly tests`_:
find a revision (12-chars alphanumeric string, e.g. "963e808156b3")
that passed at least the
``{linux32}`` tests (corresponding to a ``+`` sign on the
line ``success``) and then, in your cloned repository, switch to this revision
using::

    hg up -r XXXXX

where XXXXX is the revision id.

.. _our nightly tests: http://buildbot.pypy.org/summary?branch=<trunk>


Install build-time dependencies
-------------------------------
(**Note**: for some hints on how to translate the Python interpreter under
Windows, see the `windows document`_ . For hints on how to cross-compile in
a chroot using scratchbox2, see the `arm document`_ in the 
`RPython documentation`_)

.. _`windows document`: windows.html
.. _`arm document`: http://rpython.readthedocs.org/en/latest/arm.html
.. _`RPython documentation`: http://rpython.readthedocs.org


To build PyPy on Unix using the C translation backend, you need at least a C
compiler and ``make`` installed. Further, some optional modules have additional
dependencies:

cffi, ctypes
    libffi, pkg-config

zlib
    libz

bz2
    libbz2

pyexpat
    libexpat1

_ssl
    libssl

Make sure to have these libraries (with development headers) installed
before building PyPy, otherwise the resulting binary will not contain
these modules.  Furthermore, the following libraries should be present
after building PyPy, otherwise the corresponding CFFI modules are not
built (you can run or re-run `pypy/tool/release/package.py` to retry
to build them; you don't need to re-translate the whole PyPy):

sqlite3
    libsqlite3

curses
    libncurses

gdbm
    libgdbm-dev

tk
    tk-dev

lzma (PyPy3 only)
    liblzma

To run untranslated tests, you need the Boehm garbage collector libgc.

On Debian, this is the command to install all build-time dependencies::

    apt-get install gcc make libffi-dev pkg-config libz-dev libbz2-dev \
    libsqlite3-dev libncurses-dev libexpat1-dev libssl-dev libgdbm-dev \
    tk-dev libgc-dev \
    liblzma-dev  # For lzma on PyPy3.

On Fedora::

    dnf install gcc make libffi-devel pkgconfig zlib-devel bzip2-devel \
    lib-sqlite3-devel ncurses-devel expat-devel openssl-devel tk-devel \
    gdbm-devel \
    xz-devel  # For lzma on PyPy3.

On SLES11::

    zypper install gcc make python-devel pkg-config \
    zlib-devel libopenssl-devel libbz2-devel sqlite3-devel \
    libexpat-devel libffi-devel python-curses \
    xz-devel  # For lzma on PyPy3.
    (XXX plus the SLES11 version of libgdbm-dev and tk-dev)

On Mac OS X, most of these build-time dependencies are installed alongside
the Developer Tools. However, note that in order for the installation to
find them you may need to run::

    xcode-select --install


Run the translation
-------------------

Translate with JIT::

    cd pypy/goal
    pypy ../../rpython/bin/rpython --opt=jit

Translate without JIT::

    cd pypy/goal
    pypy ../../rpython/bin/rpython --opt=2

(You can use ``python`` instead of ``pypy`` here, which will take longer
but works too.)

If everything works correctly this will create an executable ``pypy-c`` in the
current directory. The executable behaves mostly like a normal Python
interpreter (see :doc:`cpython_differences`).

Build cffi import libraries for the stdlib
------------------------------------------

Various stdlib modules require a separate build step to create the cffi
import libraries in the `out-of-line API mode`_. This is done by the following
command::

   PYTHONPATH=. ./pypy-c pypy/tool/build_cffi_imports.py

.. _`out-of-line API mode`: http://cffi.readthedocs.org/en/latest/overview.html#real-example-api-level-out-of-line

Translating with non-standard options
-------------------------------------

It is possible to have non-standard features enabled for translation,
but they are not really tested any more.  Look, for example, at the
:doc:`objspace proxies <objspace-proxies>` document.


Packaging (preparing for installation)
--------------------------------------

Packaging is required if you want to install PyPy system-wide, even to
install on the same machine.  The reason is that doing so prepares a
number of extra features that cannot be done lazily on a root-installed
PyPy, because the normal users don't have write access.  This concerns
mostly libraries that would normally be compiled if and when they are
imported the first time.

::
    
    cd pypy/tool/release
    ./package.py pypy-VER-PLATFORM

This creates a clean and prepared hierarchy, as well as a ``.tar.bz2``
with the same content; both are found by default in
``/tmp/usession-YOURNAME/build/``.  You can then either move the file
hierarchy or unpack the ``.tar.bz2`` at the correct place.


Installation
------------

PyPy dynamically finds the location of its libraries depending on the location
of the executable. The directory hierarchy of a typical PyPy installation
looks like this::

    ./bin/pypy
    ./include/
    ./lib_pypy/
    ./lib-python/2.7
    ./site-packages/

The hierarchy shown above is relative to a PREFIX directory. PREFIX is
computed by starting from the directory where the executable resides, and
"walking up" the filesystem until we find a directory containing ``lib_pypy``
and ``lib-python/2.7``.

To install PyPy system wide on unix-like systems, it is recommended to put the
whole hierarchy alone (e.g. in ``/opt/pypy``) and put a symlink to the
``pypy`` executable into ``/usr/bin`` or ``/usr/local/bin``.

If the executable fails to find suitable libraries, it will report ``debug:
WARNING: library path not found, using compiled-in sys.path`` and then attempt
to continue normally. If the default path is usable, most code will be fine.
However, the ``sys.prefix`` will be unset and some existing libraries assume
that this is never the case.


