Nuitka Release 0.5.5

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 is finally making full use of SSA analysis knowledge for code generation, leading to many enhancements over previous releases.

It also adds support for Python3.4, which has been longer in the making, due to many rather subtle issues. In fact, even more work will be needed to fully solve remaining minor issues, but these should affect no real code.

And then there is much improved support for using standalone mode together with virtualenv. This combination was not previously supported, but should work now.

New Features

  • Added support for Python3.4

    This means support for clear method of frames to close generators, dynamic __qualname__, affected by global statements, tuples as yield from arguments, improved error messages, additional checks, and many more detail changes.

New Optimization

  • Using SSA knowledge, local variable assignments now no longer need to check if they need to release previous values, they know definitely for the most cases.

    def f():
        a = 1 # This used to check if old value of "a" needs a release
        ...
    
  • Using SSA knowledge, local variable references now no longer need to check for raising exceptions, let alone produce exceptions for cases, where that cannot be.

    def f():
        a = 1
        return a # This used to check if "a" is assigned
    
  • Using SSA knowledge, local variable references now are known if they can raise the UnboundLocalError exception or not. This allows to eliminate frame usages for many cases. Including the above example.

  • Using less memory for keeping variable information.

  • Also using less memory for constant nodes.

Bug Fixes

  • The standalone freezing code was reading Python source as UTF-8 and not using the code that handles the Python encoding properly. On some platforms there are files in standard library that are not encoded like that.

  • The fiber implementation for Linux amd64 was not working with glibc from RHEL 5. Fixed to use now multiple int to pass pointers as necessary. Also use uintptr_t instead of intprt_t to transport pointers, which may be more optimal.

  • Line numbers for exceptions were corrupted by with statements due to setting line numbers even for statements marked as internal.

  • Partial support for win32com by adding support for its hidden __path__ change.

  • Python3: Finally figured out proper chaining of exceptions, given proper context messages for exception raised during the handling of exceptions.

  • Corrected C++ memory leak for each closure variable taken, each time a function object was created.

  • Python3: Raising exceptions with tracebacks already attached, wasn't using always them, but producing new ones instead.

  • Some constants could cause errors, as they cannot be handled with the marshal module as expected, e.g. (int,).

  • Standalone: Make sure to propagate sys.path to the Python instance used to check for standard library import dependencies. This is important for virtualenv environments, which need site.py to set the path, which is not executed in that mode.

  • Windows: Added support for different path layout there, so using virtualenv should work there too.

  • The code object flag "optimized" (fast locals as opposed to locals dictionary) for functions was set wrongly to value for the parent, but for frames inside it, one with the correct value. This lead to more code objects than necessary and false co_flags values attached to the function.

  • Options passed to nuitka-python could get lost.

    nuitka-python program.py argument1 argument2 ...
    

    The above is supposed to compile program.py, execute it immediately and pass the arguments to it. But when Nuitka decides to restart itself, it would forget these options. It does so to e.g. disable hash randomization as it would affect code generation.

  • Raising tuples exception as exceptions was not compatible (Python2) or reference leaking (Python3).

Tests

  • Running 2to3 is now avoided for tests that are already running on both Python2 and Python3.
  • Made XML based optimization tests work with Python3 too. Previously these were only working on Python2.
  • Added support for ignoring messages that come from linking against self compiled Pythons.
  • Added test case for threaded generators that tortures the fiber layer a bit and exposed issues on RHEL 5.
  • Made reference count test of compiled functions generic. No more code duplication, and automatic detection of shared stuff. Also a more clear interface for disabling test cases.
  • Added Python2 specific reference counting tests, so the other cases can be executed with Python3 directly, making debugging them less tedious.

Cleanups

  • Really important removal of "variable references". They didn't solve any problem anymore, but their complexity was not helpful either. This allowed to make SSA usable finally, and removed a lot of code.
  • Removed special code generation for parameter variables, and their dedicated classes, no more needed, as every variable access code is now optimized like this.
  • Stop using C++ class methods at all. Now only the destructor of local variables is actually supposed to do anything, and their are no methods anymore. The unused var_name got removed, setVariableValue is now done manually.
  • Moved assertions for the fiber layer to a common place in the header, so they are executed on all platforms in debug mode.
  • As usual, also a bunch of cleanups for PyLint were applied.
  • The locals built-in code now uses code generation for accessing local variable values instead having its own stuff.

Organizational

  • The Python version 3.4 is now officially supported. There are a few problems open, that will be addressed in future releases, none of which will affect normal people though.

  • Major cleanup of Nuitka options.

    • Windows specific stuff is now in a dedicated option group. This includes options for icon, disabling console, etc.
    • There is now a dedicated group for controlling backend compiler choices and options.
  • Also pickup g++44 automatically, which makes using Nuitka on CentOS5 more automatic.

Summary

This release represents a very important step ahead. Using SSA for real stuff will allow us to build the trust necessary to take the next steps. Using the SSA information, we could start implementing more optimizations.

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