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73 lines
1.9 KiB
C++
73 lines
1.9 KiB
C++
#pragma once
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#include <type_traits>
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#include <common/likely.h>
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#include <Common/Exception.h>
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#include <Common/config.h>
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#include <DataTypes/NumberTraits.h>
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namespace DB
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{
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namespace ErrorCodes
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{
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extern const int ILLEGAL_DIVISION;
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}
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wsign-compare"
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template <typename A, typename B>
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inline void throwIfDivisionLeadsToFPE(A a, B b)
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{
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/// Is it better to use siglongjmp instead of checks?
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if (unlikely(b == 0))
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throw Exception("Division by zero", ErrorCodes::ILLEGAL_DIVISION);
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/// 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))
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throw Exception("Division of minimal signed number by minus one", ErrorCodes::ILLEGAL_DIVISION);
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}
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template <typename A, typename B>
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inline bool divisionLeadsToFPE(A a, B b)
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{
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if (unlikely(b == 0))
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return true;
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if (unlikely(is_signed_v<A> && is_signed_v<B> && a == std::numeric_limits<A>::min() && b == -1))
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return true;
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return false;
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}
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#pragma GCC diagnostic pop
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template <typename A, typename B>
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struct DivideIntegralImpl
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{
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using ResultType = typename NumberTraits::ResultOfIntegerDivision<A, B>::Type;
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template <typename Result = ResultType>
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static inline Result apply(A a, B b)
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{
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throwIfDivisionLeadsToFPE(a, b);
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/// Otherwise overflow may occur due to integer promotion. Example: int8_t(-1) / uint64_t(2).
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/// 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;
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}
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#if USE_EMBEDDED_COMPILER
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static constexpr bool compilable = false; /// don't know how to throw from LLVM IR
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#endif
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};
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}
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