mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2026-01-31 01:35:20 +01:00
2d8ec49fc8
Provide checkedAdd and checkedMul functions, providing checked arithmetic on signed integers. Differential Revision: https://reviews.llvm.org/D43704 llvm-svn: 326516
84 lines
2.9 KiB
C++
84 lines
2.9 KiB
C++
//==-- 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
|