Nuitka Release 0.4.6

This is to inform you about the new stable release of Nuitka. It is the extremely compatible Python compiler. Please see the page "What is Nuitka?" for an overview.

This release includes progress on all fronts. The primary focus was to advance SSA optimization over older optimization code that was already in place. In this domain, there are mostly cleanups.

Another focus has been to enhance Scons with MSVC on Windows. Nuitka now finds an installed MSVC compiler automatically, properly handles architecture of Python and Windows. This improves usability a lot.

Then this is also very much about bug fixes. There have been several hot fixes for the last release, but a complicated and major issue forced a new release, and many other small issues.

And then there is performance. As can be seen in the performance graph, this release is the fastest so far. This came mainly from examining the need for comparison slots for compiled types.

And last, but not least, this also expands the base of supported platforms, adding Gentoo, and self compiled Python to the mix.

Bug Fixes

  • Support Nuitka being installed to a path that contains spaces and handle main programs with spaces in their paths. Issue#106. Fixed in already.

  • Support Python being installed to a path that contains spaces. Issue#106. Fixed in already.

  • Windows: User provided constants larger than 65k didn't work with MSVC. Issue#108. Fixed in already.

  • Windows: The option --windows-disable-console was not effective with MSVC. Issue#107. Fixed in already.

  • Windows: For some users, Scons was detecting their MSVC installation properly already from registry, but it didn't honor the target architecture. Issue#99. Fixed in already.

  • When creating Python modules, these were marked as executable ("x" bit), which they are of course not. Fixed in already.

  • Python3.3: On architectures where Py_ssize_t is not the same as long this could lead to errors. Fixed in already.

  • Code that was using nested mutable constants and changed the nested ones was not executing correctly. Issue#112.

  • Python2: Due to list contractions being re-formulated as functions, del was rejected for the variables assigned in the contraction. Issue#111.

    [ expr(x) for x in iterable() ]
    del x # Should work, was gave an unjustified SyntaxError.

New Features

  • Compiled types when used in Python comparison now work. Code like this will work:

    def f():
    assert type(f) == types.FunctionType

    This of course also works for in operator, and is another step ahead in compatibility, and surprising too. And best of all, this works even if the checking code is not compiled with Nuitka.

  • Windows: Detecting MSVC installation from registry, if no compiler is already present in PATH.

  • Windows: Now options --mingw to force compilation with MinGW.

New Optimization

  • Rich comparisons (==, <, and the like) are now faster than ever before due to a full implementation of its own in Nuitka that eliminates a bit of the overhead. In the future, we will aim at giving it type hints to make it even faster. This gives a minor speed boost to PyStone of ca. 0.7% overall.
  • Integer comparisons are now treated preferably, as they are in CPython, which gives 1.3% speed boost to CPython.
  • The SSA based analysis is now used to provide variable scopes for temporary variables as well as reference count needs.


  • Replaced "value friend" based optimization code with SSA based optimization, which allowed to remove complicated and old code that was still used mainly in optimization of or and and expressions.
  • Delayed declaration of temp variables and their reference type is now performed based on information from SSA, which may given more accurate results. Not using "variable usage" profiles for this anymore.
  • The Scons interface and related code got a massive overhaul, making it more consistent and better documented. Also updated the internal copy to 2.3.0 for the platforms that use it, mostly Windows.
  • Stop using os.system and, shell = True) as it is not really portable at all, use, shell = False) instead.
  • As usual lots of cleanups related to line length issues and PyLint.


  • Added support for Gentoo Linux.
  • Added support for self compiled Python versions with and without debug enabled. Issue#110
  • Added use of Nuitka fonts for headers in manuals.
  • Does not install in-line copy of Scons only on systems where it is not going to be used, that is mostly non-Windows, and Linux where it is not already present. This makes for cleaner RPM packages.


While the SSA stuff is not yet bearing performance fruits, it starts to carry weight. Taking over the temporary variable handling now also means we can apply the same stuff to local variables later.

To make up for the delay in SSA driven performance improvements, there is more traditional code acceleration for rich comparisons, making it significant, and the bug fixes make Nuitka more compatible than ever.

So give this a roll, it's worth it. And feel free to join the mailing list or make a donation to support Nuitka.


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