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bpo-29882: _Py_popcount32() doesn't need 64x64 multiply (GH-30774)

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32x32 bits multiply is enough for _Py_popcount32().
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Victor Stinner 2022-01-22 00:54:42 +01:00 • committed by GitHub
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commit cd8de40b3b
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Include/internal/pycore_bitutils.h
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@ -125,7 +125,7 @@ _Py_popcount32(uint32_t x)
// Put count of each 8 bits into those 8 bits
x = (x + (x >> 4)) & M4;
// Sum of the 4 byte counts
return (uint32_t)((uint64_t)x * (uint64_t)SUM) >> 24;
return (x * SUM) >> 24;
#endif
}