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Slight performance improvement of "reinterpret" function

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This commit is contained in:
Alexey Milovidov 2021-12-12 03:28:35 +03:00
parent eaf1d764a7
commit 3b0f026827
1 changed files with 16 additions and 11 deletions
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27
src/Functions/reinterpretAs.cpp
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@ -24,6 +24,7 @@
#include <base/unaligned.h>
namespace DB
{
namespace ErrorCodes
@ -174,16 +175,14 @@ public:
const auto & offsets_from = col_from->getOffsets();
size_t size = offsets_from.size();
auto & vec_res = col_res->getData();
vec_res.resize(size);
vec_res.resize_fill(size);
size_t offset = 0;
for (size_t i = 0; i < size; ++i)
{
ToFieldType value{};
memcpy(&value,
memcpy(&vec_res[i],
&data_from[offset],
std::min(static_cast<UInt64>(sizeof(ToFieldType)), offsets_from[i] - offset - 1));
vec_res[i] = value;
offset = offsets_from[i];
}
@ -201,15 +200,18 @@ public:
size_t step = col_from_fixed->getN();
size_t size = data_from.size() / step;
auto & vec_res = col_res->getData();
vec_res.resize(size);
size_t offset = 0;
size_t copy_size = std::min(step, sizeof(ToFieldType));
if (sizeof(ToFieldType) <= step)
vec_res.resize(size);
else
vec_res.resize_fill(size);
for (size_t i = 0; i < size; ++i)
{
ToFieldType value{};
memcpy(&value, &data_from[offset], copy_size);
vec_res[i] = value;
memcpy(&vec_res[i], &data_from[offset], copy_size);
offset += step;
}
@ -288,7 +290,7 @@ private:
{
StringRef data = src.getDataAt(i);
std::memcpy(&data_to[offset], data.data, std::min(n, data.size));
memcpy(&data_to[offset], data.data, std::min(n, data.size));
offset += n;
}
}
@ -347,10 +349,13 @@ private:
using To = typename ToContainer::value_type;
size_t size = from.size();
to.resize_fill(size);
static constexpr size_t copy_size = std::min(sizeof(From), sizeof(To));
if (sizeof(To) <= sizeof(From))
to.resize(size);
else
to.resize_fill(size);
for (size_t i = 0; i < size; ++i)
memcpy(static_cast<void*>(&to[i]), static_cast<const void*>(&from[i]), copy_size);
}