Mark Dickinson <dicki...@gmail.com> added the comment:
Three files:
(1) bit_length7.patch just does the numbits->bit_length renaming;
otherwise it's the same as numbits-6b.patch.
(2) bit_length7_opt.patch uses the fast bitcount method that Raymond
pointed out.
(3) bit_length_pybench.patch adds a test for bit_length to pybench.
On my system (OS X 10.5.5/Core 2 Duo), on a 32-bit non-debug build of
the trunk, pybench is showing me a 4-5% speedup for the optimized
version.
(I also tried a version that uses gcc's __builtin_clzl function; this
was around 10% faster than the basic version, but of course it's not
portable.)
Added file: http://bugs.python.org/file12336/bit_length7.patch
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<http://bugs.python.org/issue3439>
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