Uh, sorry, misread your full mail, scratch that
On Wed, Nov 4, 2015 at 9:07 AM, Maciej Fijalkowski <fij...@gmail.com> wrote: > How do you check that someone did not e.g. bind something different to "len"? > > On Wed, Nov 4, 2015 at 8:50 AM, Victor Stinner <victor.stin...@gmail.com> > wrote: >> Hi, >> >> I'm writing a new "FAT Python" project to try to implement optimizations in >> CPython (inlining, constant folding, move invariants out of loops, etc.) >> using a "static" optimizer (not a JIT). For the background, see the thread >> on python-ideas: >> https://mail.python.org/pipermail/python-ideas/2015-October/036908.html >> >> See also the documentation: >> https://hg.python.org/sandbox/fatpython/file/tip/FATPYTHON.rst >> https://hg.python.org/sandbox/fatpython/file/tip/ASTOPTIMIZER.rst >> >> I implemented the most basic optimization to test my code: replace calls to >> builtin functions (with constant arguments) with the result. For example, >> len("abc") is replaced with 3. I reached the second milestone: it's now >> possible to run the full Python test suite with these optimizations enabled. >> It confirms that the optimizations don't break the Python semantic. >> >> Example: >> --- >>>>> def func(): >> ... return len("abc") >> ... >>>>> import dis >>>>> dis.dis(func) >> 2 0 LOAD_GLOBAL 0 (len) >> 3 LOAD_CONST 1 ('abc') >> 6 CALL_FUNCTION 1 (1 positional, 0 keyword pair) >> 9 RETURN_VALUE >> >>>>> len(func.get_specialized()) >> 1 >>>>> specialized=func.get_specialized()[0] >>>>> dis.dis(specialized['code']) >> 2 0 LOAD_CONST 1 (3) >> 3 RETURN_VALUE >>>>> len(specialized['guards']) >> 2 >> >>>>> func() >> 3 >> >>>>> len=lambda obj: "mock" >>>>> func() >> 'mock' >>>>> func.get_specialized() >> [] >> --- >> >> The function func() has specialized bytecode which returns directly 3 >> instead of calling len("abc"). The specialized bytecode has two guards >> dictionary keys: builtins.__dict__['len'] and globals()['len']. If one of >> these keys is modified, the specialized bytecode is simply removed (when the >> function is called) and the original bytecode is executed. >> >> >> You cannot expect any speedup at this milestone, it's just to validate the >> implementation. You can only get speedup if you implement *manually* >> optimizations. See for example posixpath.isabs() which inlines manually the >> call to the _get_sep() function. More optimizations will be implemented in >> the third milestone. I don't know yet if I will be able to implement >> constant folding, function inlining and/or moving invariants out of loops. >> >> >> Download, compile and test FAT Python with: >> >> hg clone http://hg.python.org/sandbox/fatpython >> ./configure && make && ./python -m test test_astoptimizer test_fat >> >> >> Currently, only 24 functions are specialized in the standard library. >> Calling a builtin function with constant arguments in not common (it was >> expected, it's only the first step for my optimizer). But 161 functions are >> specialized in tests. >> >> >> To be honest, I had to modify some tests to make them pass in FAT mode. But >> most changes are related to the .pyc filename, or to the exact size in bytes >> of dictionary objects. >> >> FAT Python is still experimental. Currently, the main bug is that the AST >> optimizer can optimize a call to a function which is not the expected >> builtin function. I already started to implement code to understand >> namespaces (detect global and local variables), but it's not enough yet to >> detect when a builtin is overriden. See TODO.rst for known bugs and >> limitations. >> >> Victor >> >> _______________________________________________ >> Python-Dev mailing list >> Python-Dev@python.org >> https://mail.python.org/mailman/listinfo/python-dev >> Unsubscribe: >> https://mail.python.org/mailman/options/python-dev/fijall%40gmail.com >> _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
