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Reasonable performance for function bitCount

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This commit is contained in:
Alexey Milovidov 2020-01-19 00:59:07 +03:00
parent 93887371f3
commit 28ad3b46da
1 changed files with 6 additions and 1 deletions
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7
dbms/src/Functions/bitCount.cpp
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@ -16,7 +16,12 @@ struct BitCountImpl
/// We count bits in the value representation in memory. For example, we support floats.
/// We need to avoid sign-extension when converting signed numbers to larger type. So, uint8_t(-1) has 8 bits.
return __builtin_popcountll(ext::bit_cast<unsigned long long>(a));
if constexpr (std::is_same_v<A, UInt64> || std::is_same_v<A, Int64>)
return __builtin_popcountll(a);
if constexpr (std::is_same_v<A, UInt32> || std::is_same_v<A, Int32> || std::is_unsigned_v<A>)
return __builtin_popcount(a);
else
return __builtin_popcountll(ext::bit_cast<unsigned long long>(a));
}
#if USE_EMBEDDED_COMPILER