ClickHouse/dbms/Functions/DivisionUtils.h

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#pragma once
#include <type_traits>
#include <Common/Exception.h>
#include <Common/config.h>
#include <DataTypes/NumberTraits.h>
namespace DB
{
namespace ErrorCodes
{
extern const int ILLEGAL_DIVISION;
}
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wsign-compare"
template <typename A, typename B>
inline void throwIfDivisionLeadsToFPE(A a, B b)
{
/// Is it better to use siglongjmp instead of checks?
if (unlikely(b == 0))
throw Exception("Division by zero", ErrorCodes::ILLEGAL_DIVISION);
/// http://avva.livejournal.com/2548306.html
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if (unlikely(is_signed_v<A> && is_signed_v<B> && a == std::numeric_limits<A>::min() && b == -1))
throw Exception("Division of minimal signed number by minus one", ErrorCodes::ILLEGAL_DIVISION);
}
template <typename A, typename B>
inline bool divisionLeadsToFPE(A a, B b)
{
if (unlikely(b == 0))
return true;
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if (unlikely(is_signed_v<A> && is_signed_v<B> && a == std::numeric_limits<A>::min() && b == -1))
return true;
return false;
}
#pragma GCC diagnostic pop
template <typename A, typename B>
struct DivideIntegralImpl
{
using ResultType = typename NumberTraits::ResultOfIntegerDivision<A, B>::Type;
static const constexpr bool allow_fixed_string = false;
template <typename Result = ResultType>
static inline Result apply(A a, B b)
{
throwIfDivisionLeadsToFPE(a, b);
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/// Otherwise overflow may occur due to integer promotion. Example: int8_t(-1) / uint64_t(2).
/// NOTE: overflow is still possible when dividing large signed number to large unsigned number or vice-versa. But it's less harmful.
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if constexpr (is_integral_v<A> && is_integral_v<B> && (is_signed_v<A> || is_signed_v<B>))
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return std::make_signed_t<A>(a) / std::make_signed_t<B>(b);
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else
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return a / b;
}
#if USE_EMBEDDED_COMPILER
static constexpr bool compilable = false; /// don't know how to throw from LLVM IR
#endif
};
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template <typename A, typename B>
struct ModuloImpl
{
using ResultType = typename NumberTraits::ResultOfModulo<A, B>::Type;
static const constexpr bool allow_fixed_string = false;
template <typename Result = ResultType>
static inline Result apply(A a, B b)
{
throwIfDivisionLeadsToFPE(typename NumberTraits::ToInteger<A>::Type(a), typename NumberTraits::ToInteger<B>::Type(b));
return typename NumberTraits::ToInteger<A>::Type(a) % typename NumberTraits::ToInteger<B>::Type(b);
}
#if USE_EMBEDDED_COMPILER
static constexpr bool compilable = false; /// don't know how to throw from LLVM IR
#endif
};
}