New submission from Ma Lin <malin...@163.com>:
C type `long` is 4-byte integer in 64-bit Windows build. [1]
But `ucs1lib_find_max_char()` function [2] uses SIZEOF_LONG, so it loses a
little performance in 64-bit Windows build.
Below is the benchmark of using SIZEOF_SIZE_T and this change:
- unsigned long value = *(unsigned long *) _p;
+ sizt_t value = *(sizt_t *) _p;
D:\dev\cpython\PCbuild\amd64\python.exe -m pyperf timeit -s "b=b'a'*10_000_000;
f=b.decode;" "f('latin1')"
before: 5.83 ms +- 0.05 ms
after : 5.58 ms +- 0.06 ms
[1] https://stackoverflow.com/questions/384502
[2]
https://github.com/python/cpython/blob/v3.8.0b4/Objects/stringlib/find_max_char.h#L9
Maybe there can be more optimizations, so I didn't prepare a PR for this.
----------
components: Interpreter Core
messages: 352970
nosy: Ma Lin, inada.naoki, serhiy.storchaka, sir-sigurd
priority: normal
severity: normal
status: open
title: micro-optimize ucs1lib_find_max_char in Windows 64-bit build
type: performance
versions: Python 3.9
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue38252>
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