Ma Lin <malin...@163.com> added the comment:
> This change produces tiny, but measurable speed-up for handling small ints
I didn't get measurable change, I run this command a dozen times and take the
best result:
D:\dev\cpython\PCbuild\amd64\python.exe -m pyperf timeit -s "from collections
import deque; consume = deque(maxlen=0).extend; r = range(256)" "consume(r)"
--duplicate=1000
before: Mean +- std dev: 771 ns +- 16 ns
after: Mean +- std dev: 770 ns +- 10 ns
Environment:
64-bit release build by MSVC 2017
CPU: i3 4160, System: latest Windows 10 64-bit
Check the machine code from godbolt.org, x64 MSVC v19.14 only saves one
instruction:
movsxd rax, ecx
x86-64 GCC 9.2 saves two instructions:
lea eax, [rdi+5]
cdqe
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<https://bugs.python.org/issue38015>
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