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Codechange: Make OverflowSafeInt constexpr
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@LordAro
LordAro committed Jul 20, 2021
1 parent 27da300 commit 2a0a219
Showing 1 changed file with 87 additions and 80 deletions.
167 changes: 87 additions & 80 deletions src/core/overflowsafe_type.hpp
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Expand Up @@ -36,21 +36,21 @@ class OverflowSafeInt
/** The non-overflow safe backend to store the value in. */
T m_value;
public:
OverflowSafeInt() : m_value(0) { }
constexpr OverflowSafeInt() : m_value(0) { }

OverflowSafeInt(const OverflowSafeInt& other) { this->m_value = other.m_value; }
OverflowSafeInt(const int64 int_) { this->m_value = int_; }
constexpr OverflowSafeInt(const OverflowSafeInt& other) : m_value(other.m_value) { }
constexpr OverflowSafeInt(const int64 int_) : m_value(int_) { }

inline OverflowSafeInt& operator = (const OverflowSafeInt& other) { this->m_value = other.m_value; return *this; }
inline constexpr OverflowSafeInt& operator = (const OverflowSafeInt& other) { this->m_value = other.m_value; return *this; }

inline OverflowSafeInt operator - () const { return OverflowSafeInt(this->m_value == T_MIN ? T_MAX : -this->m_value); }
inline constexpr OverflowSafeInt operator - () const { return OverflowSafeInt(this->m_value == T_MIN ? T_MAX : -this->m_value); }

/**
* Safe implementation of addition.
* @param other the amount to add
* @note when the addition would yield more than T_MAX, it will be T_MAX.
*/
inline OverflowSafeInt& operator += (const OverflowSafeInt& other)
inline constexpr OverflowSafeInt& operator += (const OverflowSafeInt& other)
{
#ifdef HAS_OVERFLOW_BUILTINS
if (unlikely(__builtin_add_overflow(this->m_value, other.m_value, &this->m_value))) {
Expand All @@ -73,7 +73,7 @@ class OverflowSafeInt
* @param other the amount to subtract
* @note when the subtraction would yield less than T_MIN, it will be T_MIN.
*/
inline OverflowSafeInt& operator -= (const OverflowSafeInt& other)
inline constexpr OverflowSafeInt& operator -= (const OverflowSafeInt& other)
{
#ifdef HAS_OVERFLOW_BUILTINS
if (unlikely(__builtin_sub_overflow(this->m_value, other.m_value, &this->m_value))) {
Expand All @@ -91,29 +91,29 @@ class OverflowSafeInt
return *this;
}

/* Operators for addition and subtraction */
inline OverflowSafeInt operator + (const OverflowSafeInt& other) const { OverflowSafeInt result = *this; result += other; return result; }
inline OverflowSafeInt operator + (const int other) const { OverflowSafeInt result = *this; result += (int64)other; return result; }
inline OverflowSafeInt operator + (const uint other) const { OverflowSafeInt result = *this; result += (int64)other; return result; }
inline OverflowSafeInt operator - (const OverflowSafeInt& other) const { OverflowSafeInt result = *this; result -= other; return result; }
inline OverflowSafeInt operator - (const int other) const { OverflowSafeInt result = *this; result -= (int64)other; return result; }
inline OverflowSafeInt operator - (const uint other) const { OverflowSafeInt result = *this; result -= (int64)other; return result; }
/* Operators for addition and subtraction. */
inline constexpr OverflowSafeInt operator + (const OverflowSafeInt& other) const { OverflowSafeInt result = *this; result += other; return result; }
inline constexpr OverflowSafeInt operator + (const int other) const { OverflowSafeInt result = *this; result += (int64)other; return result; }
inline constexpr OverflowSafeInt operator + (const uint other) const { OverflowSafeInt result = *this; result += (int64)other; return result; }
inline constexpr OverflowSafeInt operator - (const OverflowSafeInt& other) const { OverflowSafeInt result = *this; result -= other; return result; }
inline constexpr OverflowSafeInt operator - (const int other) const { OverflowSafeInt result = *this; result -= (int64)other; return result; }
inline constexpr OverflowSafeInt operator - (const uint other) const { OverflowSafeInt result = *this; result -= (int64)other; return result; }

inline OverflowSafeInt& operator ++ () { return *this += 1; }
inline OverflowSafeInt& operator -- () { return *this += -1; }
inline OverflowSafeInt operator ++ (int) { OverflowSafeInt org = *this; *this += 1; return org; }
inline OverflowSafeInt operator -- (int) { OverflowSafeInt org = *this; *this += -1; return org; }
inline constexpr OverflowSafeInt& operator ++ () { return *this += 1; }
inline constexpr OverflowSafeInt& operator -- () { return *this += -1; }
inline constexpr OverflowSafeInt operator ++ (int) { OverflowSafeInt org = *this; *this += 1; return org; }
inline constexpr OverflowSafeInt operator -- (int) { OverflowSafeInt org = *this; *this += -1; return org; }

/**
* Safe implementation of multiplication.
* @param factor the factor to multiply this with.
* @note when the multiplication would yield more than T_MAX (or less than T_MIN),
* it will be T_MAX (respectively T_MIN).
*/
inline OverflowSafeInt& operator *= (const int factor)
inline constexpr OverflowSafeInt& operator *= (const int factor)
{
#ifdef HAS_OVERFLOW_BUILTINS
bool is_result_positive = (this->m_value < 0) == (factor < 0); // -ve * -ve == +ve
const bool is_result_positive = (this->m_value < 0) == (factor < 0); // -ve * -ve == +ve
if (unlikely(__builtin_mul_overflow(this->m_value, factor, &this->m_value))) {
this->m_value = is_result_positive ? T_MAX : T_MIN;
}
Expand All @@ -135,75 +135,82 @@ class OverflowSafeInt
return *this;
}

/* Operators for multiplication */
inline OverflowSafeInt operator * (const int64 factor) const { OverflowSafeInt result = *this; result *= factor; return result; }
inline OverflowSafeInt operator * (const int factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }
inline OverflowSafeInt operator * (const uint factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }
inline OverflowSafeInt operator * (const uint16 factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }
inline OverflowSafeInt operator * (const byte factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }
/* Operators for multiplication. */
inline constexpr OverflowSafeInt operator * (const int64 factor) const { OverflowSafeInt result = *this; result *= factor; return result; }
inline constexpr OverflowSafeInt operator * (const int factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }
inline constexpr OverflowSafeInt operator * (const uint factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }
inline constexpr OverflowSafeInt operator * (const uint16 factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }
inline constexpr OverflowSafeInt operator * (const byte factor) const { OverflowSafeInt result = *this; result *= (int64)factor; return result; }

/* Operators for division */
inline OverflowSafeInt& operator /= (const int64 divisor) { this->m_value /= divisor; return *this; }
inline OverflowSafeInt operator / (const OverflowSafeInt& divisor) const { OverflowSafeInt result = *this; result /= divisor.m_value; return result; }
inline OverflowSafeInt operator / (const int divisor) const { OverflowSafeInt result = *this; result /= divisor; return result; }
inline OverflowSafeInt operator / (const uint divisor) const { OverflowSafeInt result = *this; result /= (int)divisor; return result; }
/* Operators for division. */
inline constexpr OverflowSafeInt& operator /= (const int64 divisor) { this->m_value /= divisor; return *this; }
inline constexpr OverflowSafeInt operator / (const OverflowSafeInt& divisor) const { OverflowSafeInt result = *this; result /= divisor.m_value; return result; }
inline constexpr OverflowSafeInt operator / (const int divisor) const { OverflowSafeInt result = *this; result /= divisor; return result; }
inline constexpr OverflowSafeInt operator / (const uint divisor) const { OverflowSafeInt result = *this; result /= (int)divisor; return result; }

/* Operators for modulo */
inline OverflowSafeInt& operator %= (const int divisor) { this->m_value %= divisor; return *this; }
inline OverflowSafeInt operator % (const int divisor) const { OverflowSafeInt result = *this; result %= divisor; return result; }

/* Operators for shifting */
inline OverflowSafeInt& operator <<= (const int shift) { this->m_value <<= shift; return *this; }
inline OverflowSafeInt operator << (const int shift) const { OverflowSafeInt result = *this; result <<= shift; return result; }
inline OverflowSafeInt& operator >>= (const int shift) { this->m_value >>= shift; return *this; }
inline OverflowSafeInt operator >> (const int shift) const { OverflowSafeInt result = *this; result >>= shift; return result; }

/* Operators for (in)equality when comparing overflow safe ints */
inline bool operator == (const OverflowSafeInt& other) const { return this->m_value == other.m_value; }
inline bool operator != (const OverflowSafeInt& other) const { return !(*this == other); }
inline bool operator > (const OverflowSafeInt& other) const { return this->m_value > other.m_value; }
inline bool operator >= (const OverflowSafeInt& other) const { return this->m_value >= other.m_value; }
inline bool operator < (const OverflowSafeInt& other) const { return !(*this >= other); }
inline bool operator <= (const OverflowSafeInt& other) const { return !(*this > other); }

/* Operators for (in)equality when comparing non-overflow safe ints */
inline bool operator == (const int other) const { return this->m_value == other; }
inline bool operator != (const int other) const { return !(*this == other); }
inline bool operator > (const int other) const { return this->m_value > other; }
inline bool operator >= (const int other) const { return this->m_value >= other; }
inline bool operator < (const int other) const { return !(*this >= other); }
inline bool operator <= (const int other) const { return !(*this > other); }

inline operator int64 () const { return this->m_value; }
inline constexpr OverflowSafeInt& operator %= (const int divisor) { this->m_value %= divisor; return *this; }
inline constexpr OverflowSafeInt operator % (const int divisor) const { OverflowSafeInt result = *this; result %= divisor; return result; }

/* Operators for shifting. */
inline constexpr OverflowSafeInt& operator <<= (const int shift) { this->m_value <<= shift; return *this; }
inline constexpr OverflowSafeInt operator << (const int shift) const { OverflowSafeInt result = *this; result <<= shift; return result; }
inline constexpr OverflowSafeInt& operator >>= (const int shift) { this->m_value >>= shift; return *this; }
inline constexpr OverflowSafeInt operator >> (const int shift) const { OverflowSafeInt result = *this; result >>= shift; return result; }

/* Operators for (in)equality when comparing overflow safe ints. */
inline constexpr bool operator == (const OverflowSafeInt& other) const { return this->m_value == other.m_value; }
inline constexpr bool operator != (const OverflowSafeInt& other) const { return !(*this == other); }
inline constexpr bool operator > (const OverflowSafeInt& other) const { return this->m_value > other.m_value; }
inline constexpr bool operator >= (const OverflowSafeInt& other) const { return this->m_value >= other.m_value; }
inline constexpr bool operator < (const OverflowSafeInt& other) const { return !(*this >= other); }
inline constexpr bool operator <= (const OverflowSafeInt& other) const { return !(*this > other); }

/* Operators for (in)equality when comparing non-overflow safe ints. */
inline constexpr bool operator == (const int other) const { return this->m_value == other; }
inline constexpr bool operator != (const int other) const { return !(*this == other); }
inline constexpr bool operator > (const int other) const { return this->m_value > other; }
inline constexpr bool operator >= (const int other) const { return this->m_value >= other; }
inline constexpr bool operator < (const int other) const { return !(*this >= other); }
inline constexpr bool operator <= (const int other) const { return !(*this > other); }

inline constexpr operator int64 () const { return this->m_value; }
};

/* Sometimes we got int64 operator OverflowSafeInt instead of vice versa. Handle that properly */
template <class T> inline OverflowSafeInt<T> operator + (int64 a, OverflowSafeInt<T> b) { return b + a; }
template <class T> inline OverflowSafeInt<T> operator - (int64 a, OverflowSafeInt<T> b) { return -b + a; }
template <class T> inline OverflowSafeInt<T> operator * (int64 a, OverflowSafeInt<T> b) { return b * a; }
template <class T> inline OverflowSafeInt<T> operator / (int64 a, OverflowSafeInt<T> b) { return (OverflowSafeInt<T>)a / (int)b; }

/* Sometimes we got int operator OverflowSafeInt instead of vice versa. Handle that properly */
template <class T> inline OverflowSafeInt<T> operator + (int a, OverflowSafeInt<T> b) { return b + a; }
template <class T> inline OverflowSafeInt<T> operator - (int a, OverflowSafeInt<T> b) { return -b + a; }
template <class T> inline OverflowSafeInt<T> operator * (int a, OverflowSafeInt<T> b) { return b * a; }
template <class T> inline OverflowSafeInt<T> operator / (int a, OverflowSafeInt<T> b) { return (OverflowSafeInt<T>)a / (int)b; }

/* Sometimes we got uint operator OverflowSafeInt instead of vice versa. Handle that properly */
template <class T> inline OverflowSafeInt<T> operator + (uint a, OverflowSafeInt<T> b) { return b + a; }
template <class T> inline OverflowSafeInt<T> operator - (uint a, OverflowSafeInt<T> b) { return -b + a; }
template <class T> inline OverflowSafeInt<T> operator * (uint a, OverflowSafeInt<T> b) { return b * a; }
template <class T> inline OverflowSafeInt<T> operator / (uint a, OverflowSafeInt<T> b) { return (OverflowSafeInt<T>)a / (int)b; }

/* Sometimes we got byte operator OverflowSafeInt instead of vice versa. Handle that properly */
template <class T> inline OverflowSafeInt<T> operator + (byte a, OverflowSafeInt<T> b) { return b + (uint)a; }
template <class T> inline OverflowSafeInt<T> operator - (byte a, OverflowSafeInt<T> b) { return -b + (uint)a; }
template <class T> inline OverflowSafeInt<T> operator * (byte a, OverflowSafeInt<T> b) { return b * (uint)a; }
template <class T> inline OverflowSafeInt<T> operator / (byte a, OverflowSafeInt<T> b) { return (OverflowSafeInt<T>)a / (int)b; }

/* Sometimes we got int64 operator OverflowSafeInt instead of vice versa. Handle that properly. */
template <class T> inline constexpr OverflowSafeInt<T> operator + (const int64 a, const OverflowSafeInt<T> b) { return b + a; }
template <class T> inline constexpr OverflowSafeInt<T> operator - (const int64 a, const OverflowSafeInt<T> b) { return -b + a; }
template <class T> inline constexpr OverflowSafeInt<T> operator * (const int64 a, const OverflowSafeInt<T> b) { return b * a; }
template <class T> inline constexpr OverflowSafeInt<T> operator / (const int64 a, const OverflowSafeInt<T> b) { return (OverflowSafeInt<T>)a / (int)b; }

/* Sometimes we got int operator OverflowSafeInt instead of vice versa. Handle that properly. */
template <class T> inline constexpr OverflowSafeInt<T> operator + (const int a, const OverflowSafeInt<T> b) { return b + a; }
template <class T> inline constexpr OverflowSafeInt<T> operator - (const int a, const OverflowSafeInt<T> b) { return -b + a; }
template <class T> inline constexpr OverflowSafeInt<T> operator * (const int a, const OverflowSafeInt<T> b) { return b * a; }
template <class T> inline constexpr OverflowSafeInt<T> operator / (const int a, const OverflowSafeInt<T> b) { return (OverflowSafeInt<T>)a / (int)b; }

/* Sometimes we got uint operator OverflowSafeInt instead of vice versa. Handle that properly. */
template <class T> inline constexpr OverflowSafeInt<T> operator + (const uint a, const OverflowSafeInt<T> b) { return b + a; }
template <class T> inline constexpr OverflowSafeInt<T> operator - (const uint a, const OverflowSafeInt<T> b) { return -b + a; }
template <class T> inline constexpr OverflowSafeInt<T> operator * (const uint a, const OverflowSafeInt<T> b) { return b * a; }
template <class T> inline constexpr OverflowSafeInt<T> operator / (const uint a, const OverflowSafeInt<T> b) { return (OverflowSafeInt<T>)a / (int)b; }

/* Sometimes we got byte operator OverflowSafeInt instead of vice versa. Handle that properly. */
template <class T> inline constexpr OverflowSafeInt<T> operator + (const byte a, const OverflowSafeInt<T> b) { return b + (uint)a; }
template <class T> inline constexpr OverflowSafeInt<T> operator - (const byte a, const OverflowSafeInt<T> b) { return -b + (uint)a; }
template <class T> inline constexpr OverflowSafeInt<T> operator * (const byte a, const OverflowSafeInt<T> b) { return b * (uint)a; }
template <class T> inline constexpr OverflowSafeInt<T> operator / (const byte a, const OverflowSafeInt<T> b) { return (OverflowSafeInt<T>)a / (int)b; }

typedef OverflowSafeInt<int64> OverflowSafeInt64;
typedef OverflowSafeInt<int32> OverflowSafeInt32;

/* Some basic "unit tests". Also has the bonus of confirming that constexpr is working. */
static_assert(OverflowSafeInt32(INT32_MIN) - 1 == OverflowSafeInt32(INT32_MIN));
static_assert(OverflowSafeInt32(INT32_MAX) + 1 == OverflowSafeInt32(INT32_MAX));
static_assert(OverflowSafeInt32(INT32_MAX) * 2 == OverflowSafeInt32(INT32_MAX));
static_assert(OverflowSafeInt32(INT32_MIN) * 2 == OverflowSafeInt32(INT32_MIN));

#undef HAS_OVERFLOW_BUILTINS

#endif /* OVERFLOWSAFE_TYPE_HPP */

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