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modulo.cpp
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modulo.cpp
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// Copyright 2022 PingCAP, Ltd.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <Functions/DivisionUtils.h>
#include <Functions/FunctionBinaryArithmetic.h>
namespace DB
{
template <typename A, typename B>
struct ModuloImpl<A, B, false>
{
using ResultType = typename NumberTraits::ResultOfModulo<A, B>::Type;
template <typename Result = ResultType>
static Result apply(A a, B b)
{
if constexpr (std::is_floating_point_v<Result>)
{
auto x = static_cast<Result>(a);
auto y = static_cast<Result>(b);
// assert no infinite or NaN values.
assert(std::isfinite(x) && std::isfinite(y));
// C++ does not allow operator% between floating point
// values, so we call into std::fmod.
return std::fmod(x, y);
}
else // both A and B are integrals.
{
// decimals are expected to be converted to integers or floating point values before computations.
static_assert(is_integer_v<Result>);
// convert to unsigned before computing.
// we have to prevent wrong result like UInt64(5) = UInt64(5) % Int64(-3).
// in MySQL, UInt64(5) % Int64(-3) evaluates to UInt64(2).
auto x = toSafeUnsigned<Result>(a);
auto y = toSafeUnsigned<Result>(b);
auto result = static_cast<Result>(x % y);
// in MySQL, the sign of a % b is the same as that of a.
// e.g. 5 % -3 = 2, -5 % 3 = -2.
if constexpr (is_signed_v<Result>)
{
if (a < 0)
return -result;
else
return result;
}
else
return result;
}
}
template <typename Result = ResultType>
static Result apply(A a, B b, UInt8 & res_null)
{
if (unlikely(b == 0))
{
res_null = 1;
return static_cast<Result>(0);
}
return apply(a, b);
}
};
template <typename A, typename B>
struct ModuloImpl<A, B, true>
{
using ResultPrecInferer = ModDecimalInferer;
using ResultType = If<std::is_floating_point_v<A> || std::is_floating_point_v<B>, double, Decimal32>;
template <typename Result = ResultType>
static Result apply(A a, B b)
{
Result x, y;
if constexpr (IsDecimal<A>)
x = static_cast<Result>(a.value);
else
x = static_cast<Result>(a);
if constexpr (IsDecimal<B>)
y = static_cast<Result>(b.value);
else
y = static_cast<Result>(b);
return ModuloImpl<Result, Result>::apply(x, y);
}
template <typename Result = ResultType>
static Result apply(A a, B b, UInt8 & res_null)
{
if (unlikely(b == 0))
{
res_null = 1;
return static_cast<Result>(0);
}
return apply(a, b);
}
};
/// Optimizations for integer division by a constant.
#if __SSE2__
#define LIBDIVIDE_SSE2 1
#endif
#include <libdivide.h>
template <typename A, typename B>
struct ModuloByConstantImpl : BinaryOperationImplBase<A, B, ModuloImpl<A, B>>
{
using ResultType = typename ModuloImpl<A, B>::ResultType;
static void vectorConstant(const PaddedPODArray<A> & a, B b, PaddedPODArray<ResultType> & c)
{
if (unlikely(b == 0))
throw Exception("Division by zero", ErrorCodes::ILLEGAL_DIVISION);
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wsign-compare"
if (unlikely((std::is_signed_v<B> && b == -1) || b == 1))
{
size_t size = a.size();
for (size_t i = 0; i < size; ++i)
c[i] = 0;
return;
}
#pragma GCC diagnostic pop
libdivide::divider<A> divider(b);
/// Here we failed to make the SSE variant from libdivide give an advantage.
size_t size = a.size();
for (size_t i = 0; i < size; ++i)
c[i] = a[i] - (a[i] / divider) * b; /// NOTE: perhaps, the division semantics with the remainder of negative numbers is not preserved.
}
};
/** Specializations are specified for dividing numbers of the type UInt64 and UInt32 by the numbers of the same sign.
* Can be expanded to all possible combinations, but more code is needed.
*/
// clang-format off
template <> struct BinaryOperationImpl<UInt64, UInt8, ModuloImpl<UInt64, UInt8>> : ModuloByConstantImpl<UInt64, UInt8> {};
template <> struct BinaryOperationImpl<UInt64, UInt16, ModuloImpl<UInt64, UInt16>> : ModuloByConstantImpl<UInt64, UInt16> {};
template <> struct BinaryOperationImpl<UInt64, UInt32, ModuloImpl<UInt64, UInt32>> : ModuloByConstantImpl<UInt64, UInt32> {};
template <> struct BinaryOperationImpl<UInt64, UInt64, ModuloImpl<UInt64, UInt64>> : ModuloByConstantImpl<UInt64, UInt64> {};
template <> struct BinaryOperationImpl<UInt32, UInt8, ModuloImpl<UInt32, UInt8>> : ModuloByConstantImpl<UInt32, UInt8> {};
template <> struct BinaryOperationImpl<UInt32, UInt16, ModuloImpl<UInt32, UInt16>> : ModuloByConstantImpl<UInt32, UInt16> {};
template <> struct BinaryOperationImpl<UInt32, UInt32, ModuloImpl<UInt32, UInt32>> : ModuloByConstantImpl<UInt32, UInt32> {};
template <> struct BinaryOperationImpl<UInt32, UInt64, ModuloImpl<UInt32, UInt64>> : ModuloByConstantImpl<UInt32, UInt64> {};
template <> struct BinaryOperationImpl<Int64, Int8, ModuloImpl<Int64, Int8>> : ModuloByConstantImpl<Int64, Int8> {};
template <> struct BinaryOperationImpl<Int64, Int16, ModuloImpl<Int64, Int16>> : ModuloByConstantImpl<Int64, Int16> {};
template <> struct BinaryOperationImpl<Int64, Int32, ModuloImpl<Int64, Int32>> : ModuloByConstantImpl<Int64, Int32> {};
template <> struct BinaryOperationImpl<Int64, Int64, ModuloImpl<Int64, Int64>> : ModuloByConstantImpl<Int64, Int64> {};
template <> struct BinaryOperationImpl<Int32, Int8, ModuloImpl<Int32, Int8>> : ModuloByConstantImpl<Int32, Int8> {};
template <> struct BinaryOperationImpl<Int32, Int16, ModuloImpl<Int32, Int16>> : ModuloByConstantImpl<Int32, Int16> {};
template <> struct BinaryOperationImpl<Int32, Int32, ModuloImpl<Int32, Int32>> : ModuloByConstantImpl<Int32, Int32> {};
template <> struct BinaryOperationImpl<Int32, Int64, ModuloImpl<Int32, Int64>> : ModuloByConstantImpl<Int32, Int64> {};
// clang-format on
namespace
{
// clang-format off
struct NameModulo { static constexpr auto name = "modulo"; };
// clang-format on
using FunctionModulo = FunctionBinaryArithmetic<ModuloImpl_t, NameModulo, false>;
} // namespace
void registerFunctionModulo(FunctionFactory & factory)
{
factory.registerFunction<FunctionModulo>();
}
} // namespace DB