| //==-- llvm/Support/CheckedArithmetic.h - Safe arithmetical operations *- C++ // |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file contains generic functions for operating on integers which |
| // give the indication on whether the operation has overflown. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_SUPPORT_CHECKEDARITHMETIC_H |
| #define LLVM_SUPPORT_CHECKEDARITHMETIC_H |
| |
| #include "llvm/ADT/APInt.h" |
| |
| #include <type_traits> |
| |
| namespace { |
| |
| /// Utility function to apply a given method of \c APInt \p F to \p LHS and |
| /// \p RHS, and write the output into \p Res. |
| /// \return Whether the operation overflows. |
| template <typename T, typename F> |
| typename std::enable_if<std::is_integral<T>::value && sizeof(T) * 8 <= 64, |
| bool>::type |
| checkedOp(T LHS, T RHS, F Op, T *Res = nullptr, bool Signed = true) { |
| llvm::APInt ALHS(/*BitSize=*/sizeof(T) * 8, LHS, Signed); |
| llvm::APInt ARHS(/*BitSize=*/sizeof(T) * 8, RHS, Signed); |
| bool Overflow; |
| llvm::APInt Out = (ALHS.*Op)(ARHS, Overflow); |
| if (Res) |
| *Res = Signed ? Out.getSExtValue() : Out.getZExtValue(); |
| return Overflow; |
| } |
| } |
| |
| namespace llvm { |
| |
| /// Add two signed integers \p LHS and \p RHS, write into \p Res if non-null. |
| /// Does not guarantee saturating arithmetic. |
| /// \return Whether the result overflows. |
| template <typename T> |
| typename std::enable_if<std::is_signed<T>::value, bool>::type |
| checkedAdd(T LHS, T RHS, T *Res = nullptr) { |
| return checkedOp(LHS, RHS, &llvm::APInt::sadd_ov, Res); |
| } |
| |
| /// Multiply two signed integers \p LHS and \p RHS, write into \p Res if |
| /// non-null. |
| /// Does not guarantee saturating arithmetic. |
| /// \return Whether the result overflows. |
| template <typename T> |
| typename std::enable_if<std::is_signed<T>::value, bool>::type |
| checkedMul(T LHS, T RHS, T *Res = nullptr) { |
| return checkedOp(LHS, RHS, &llvm::APInt::smul_ov, Res); |
| } |
| |
| /// Add two unsigned integers \p LHS and \p RHS, write into \p Res if non-null. |
| /// Does not guarantee saturating arithmetic. |
| /// \return Whether the result overflows. |
| template <typename T> |
| typename std::enable_if<std::is_unsigned<T>::value, bool>::type |
| checkedAddUnsigned(T LHS, T RHS, T *Res = nullptr) { |
| return checkedOp(LHS, RHS, &llvm::APInt::uadd_ov, Res, /*Signed=*/false); |
| } |
| |
| /// Multiply two unsigned integers \p LHS and \p RHS, write into \p Res if |
| /// non-null. |
| /// Does not guarantee saturating arithmetic. |
| /// \return Whether the result overflows. |
| template <typename T> |
| typename std::enable_if<std::is_unsigned<T>::value, bool>::type |
| checkedMulUnsigned(T LHS, T RHS, T *Res = nullptr) { |
| return checkedOp(LHS, RHS, &llvm::APInt::umul_ov, Res, /*Signed=*/false); |
| } |
| |
| } // End llvm namespace |
| |
| #endif |