Translating on Windows¶
RPython is supported on Windows platforms, starting with Windows 2000. The following text gives some hints about how to translate a interpreter written in RPython, using PyPy as an example.
PyPy supports only being translated as a 32bit program, even on 64bit Windows. See at the end of this page for what is missing for a full 64bit translation.
To build pypy-c you need a working python environment, and a C compiler. It is possible to translate with a CPython 2.6 or later, but this is not the preferred way, because it will take a lot longer to run – depending on your architecture, between two and three times as long. So head to our downloads and get the latest stable version.
Microsoft Visual Studio is preferred as a compiler, but there are reports of success with the mingw32 port of gcc.
What Compiler to use and How to find it?¶
The first stumbling block when building something for Python on windows is how to discover the path to the compiler, headers, and libraries. One can install many versions of the MSVC compiler tools, from stand-alone build tools to full blown Visual Studio IDE installations. Each of these use cases put the compiler at different locations, and the layout changes from time to time.
distutils package, located in the stdlib, is the natural place to put
this discovery code, but it is frozen by the python version. The pip-
setuptools can move faster to adapt to new tools. So the first
thing that will happen after building PyPy is it will install pip and download
setuptools, then it will build the cffi modules used in stdlib.
PyPy has a chicken and egg problem: in order to compile something we need
setuptools, but in order to get
setuptools we need pip which requires
_ssl must be compiled. So PyPy vendors in a copy of
PyPy will prefer to compile with the latest MSVC compiler it can find, which is a departure from CPython’s desire to compile with Visual Studio 9.
Translating PyPy with Visual Studio¶
We routinely test translation of PyPy using Visual Studio 2019, MSVC160. Other configurations may work as well.
The translation scripts will set up the appropriate environment variables for the compiler, so you do not need to run vcvars before translation. They will pick the most recent Visual Studio compiler they can find. In addition, the target architecture (32 bits, 64 bits) is automatically selected. A 32 bit build can only be built using a 32 bit Python and vice versa. By default the interpreter is built using the Multi-threaded DLL (/MD) runtime environment.
If you wish to override this detection method to use a different compiler (mingw or a different version of MSVC):
- set up the PATH and other environment variables as needed
- set the CC environment variable to compiler exe to be used, for a different version of MSVC SET CC=cl.exe.
Note: The RPython translator does currently not support 64 bit Python, and translation will fail in this case.
Python and a C compiler are all you need to build pypy, but it will miss some modules that relies on third-party libraries. See below how to get and build them.
Please see the non-windows instructions for more information, especially note that translation is RAM-hungry. A standard translation requires around 4GB, so special preparations are necessary, or you may want to use the following method to reduce memory usage at the price of a slower translation:
set PYPY_GC_MAX_DELTA=200MB pypy --jit loop_longevity=300 ../../rpython/bin/rpython -Ojit targetpypystandalone set PYPY_GC_MAX_DELTA= # This is done as part of translation PYTHONPATH=../.. ./pypy-c ../../lib_pypy/pypy_tools/build_cffi_imports.py
Preparing Windows for the large build¶
Normally 32bit programs are limited to 2GB of memory on Windows. It is possible to raise this limit to almost 4GB on Windows 64bit.
You need to execute:
<path-to-visual>\vc\vcvars.bat editbin /largeaddressaware translator.exe
translator.exe is the pypy.exe or cpython.exe you will use to
translate with. This is done by default during PyPy translation, so it should
Installing external packages¶
We uses a subrepository inside pypy to hold binary compiled versions of the build dependencies for windows. As part of the rpython setup stage, environment variables will be set to use these dependencies. The repository has a README file on how to replicate, and a branch for each supported platform. You may run the get_externals.py utility to checkout the proper branch for your platform and PyPy version.
Using the mingw compiler¶
You can compile an RPython program with the mingw compiler, using the –cc=mingw32 option; gcc.exe must be on the PATH. If the -cc flag does not begin with “ming”, it should be the name of a valid gcc-derivative compiler, i.e. x86_64-w64-mingw32-gcc for the 64 bit compiler creating a 64 bit target.
You probably want to set the CPATH, LIBRARY_PATH, and PATH environment variables to the header files, lib or dlls, and dlls respectively of the locally installed packages if they are not in the mingw directory heirarchy.
libffi for the mingw compiler¶
To enable the _rawffi (and ctypes) module, you need to compile a mingw version of libffi. Here is one way to do this, wich should allow you to try to build for win64 or win32:
If you do not use cygwin, you will need msys to provide make, autoconf tools and other goodies.
- Download and unzip a msys for mingw, say into c:msys
- Edit the c:msysetcfstab file to mount c:mingw
Download and unzip the libffi source files, and extract them in the base directory.
Run c:msysmsys.bat or a cygwin shell which should make you feel better since it is a shell prompt with shell tools.
From inside the shell, cd to the libffi directory and do:
sh ./configure make cp .libs/libffi-5.dll <somewhere on the PATH>
If you can’t find the dll, and the libtool issued a warning about “undefined symbols not allowed”, you will need to edit the libffi Makefile in the toplevel directory. Add the flag -no-undefined to the definition of libffi_la_LDFLAGS
If you wish to experiment with win64, you must run configure with flags:
sh ./configure --build=x86_64-w64-mingw32 --host=x86_64-w64-mingw32
or such, depending on your mingw64 download.
hacking on PyPy with the mingw compiler¶
Since hacking on PyPy means running tests, you will need a way to specify the mingw compiler when hacking (as opposed to translating). As of March 2012, –cc is not a valid option for pytest.py. However if you set an environment variable CC to the compiler exe, testing will use it.
What is missing for a full 64-bit translation¶
The main blocker is that we assume that the integer type of RPython is large enough to (occasionally) contain a pointer value cast to an integer. The simplest fix is to make sure that it is so, but it will give the following incompatibility between CPython and PyPy on Win64:
sys.maxint == 2**31-1, sys.maxsize == 2**63-1
sys.maxint == sys.maxsize == 2**63-1
…and, correspondingly, PyPy supports ints up to the larger value of
sys.maxint before they are converted to
long. The first decision
that someone needs to make is if this incompatibility is reasonable.
Assuming that it is, the first thing to do is probably to hack CPython
until it fits this model: replace the field in PyIntObject with a
long field, and change the value of
sys.maxint. This might just
work, even if half-brokenly: I’m sure you can crash it because of the
precision loss that undoubtedly occurs everywhere, but try not to. :-)
Such a hacked CPython is what you’ll use in the next steps. We’ll call it CPython64/64.
It is probably not too much work if the goal is only to get a translated
PyPy executable, and to run all tests before translation. But you need
to start somewhere, and you should start with some tests in
test_newgc.py: try to have them pass on top of CPython64/64.
Keep in mind that this runs small translations, and some details may go
wrong. The most obvious one is to check that it produces C files that
use the integer type
Signed — but what is
Signed defined to?
It should be equal to
long on every other platform, but on Win64 it
should be something like
What is more generally needed is to review all the C files in
rpython/translator/c/src for the word
long, because this means a
32-bit integer even on Win64. Replace it with
Signed most of the
times. You can replace one with the other without breaking anything on
any other platform, so feel free to.
Then, these two C types have corresponding RPython types:
lltype.Signed respectively. The first should really correspond
to the C
long. Add tests that check that integers cast to one
type or the other really have 32 and 64 bits respectively, on Win64.
Once these basic tests work, you need to review
lltype.Signed. The goal would be to
fix some more
LONG-versus-Signed issues, by fixing the tests — as
always run on top of CPython64/64. Note that there was some early work
rpython/rlib/rarithmetic with the goal of running all the
tests on Win64 on the regular CPython, but I think by now that it’s a
bad idea. Look only at CPython64/64.
The major intermediate goal is to get a translation of PyPy with
with a minimal set of modules, starting with
you need to use CPython64/64 to run this translation too. Check
carefully the warnings of the C compiler at the end. By default, MSVC
reports a lot of mismatches of integer sizes as warnings instead of
Then you need to review
issues. At some time during this review, we get a working translated
PyPy on Windows 64 that includes all
everything needed to run translations. Once we have that, the hacked
CPython64/64 becomes much less important, because we can run future
translations on top of this translated PyPy. As soon as we get there,
please distribute the translated PyPy. It’s an essential component
for anyone else that wants to work on Win64! We end up with a strange
kind of dependency — we need a translated PyPy in order to translate a
PyPy —, but I believe it’s ok here, as Windows executables are
supposed to never be broken by newer versions of Windows.
Happy hacking :-)