Message 217800 - Python tracker

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Author	vstinner
Recipients	vstinner
Date	2014-05-02.21:54:22
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	<1399067662.75.0.0621982207381.issue21420@psf.upfronthosting.co.za>
In-reply-to

Content
The algorithm for 2 n (long_pow) is slower than 1 << n algorithm (long_lshift). I propose to compute xy as 1<<y if x==2 and y >= 0. Attached patch implements this idea. According to my microbenchmark, it is 4x faster to small power (20 .. 21024) and up to 340x faster for large power (2(228)).

The algorithm for 2 ** n (long_pow) is slower than 1 << n algorithm (long_lshift). I propose to compute x**y as 1<<y if x==2 and y >= 0.

Attached patch implements this idea. According to my microbenchmark, it is 4x faster to small power (2**0 .. 2**1024) and up to 340x faster for large power (2**(2**28)).

History
Date	User	Action	Args
2014-05-02 21:54:22	vstinner	set	recipients: + vstinner
2014-05-02 21:54:22	vstinner	set	messageid: <1399067662.75.0.0621982207381.issue21420@psf.upfronthosting.co.za>
2014-05-02 21:54:22	vstinner	link	issue21420 messages
2014-05-02 21:54:22	vstinner	create