[New-bugs-announce] [issue46020] Optimize long_pow for the common case

[Raymond Hettinger]

New submission from Raymond Hettinger <raymond.hettinger at gmail.com>:

The expression 'x * x' is faster than 'x ** 2'.

In Python3.10, the speed difference was enormous.  Due to ceval optimizations, the difference in Python3.11 is tighter; however, there is still room for improvement.

The code for long_pow() doesn't currently have a fast path for squaring which is by far the most important case.

$ python3.10 -m timeit -r 11 -s 'x = 10' 'x ** 2'
1000000 loops, best of 11: 201 nsec per loop
$ python3.10 -m timeit -r 11 -s 'x = 10' 'x * x'
10000000 loops, best of 11: 21.9 nsec per loop

$ python3.11 -m timeit -r 11 -s 'x = 10' 'x ** 2'
10000000 loops, best of 11: 32 nsec per loop
$ python3.11 -m timeit -r 11 -s 'x = 10' 'x * x'
20000000 loops, best of 11: 17.6 nsec per loop

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components: Interpreter Core
messages: 408076
nosy: rhettinger
priority: normal
severity: normal
status: open
title: Optimize long_pow for the common case
type: performance

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue46020>
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