//==-- llvm/Support/CheckedArithmetic.h - Safe arithmetical operations *- C++ // // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// // // 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 "llvm/ADT/Optional.h" #include namespace { /// Utility function to apply a given method of \c APInt \p F to \p LHS and /// \p RHS. /// \return Empty optional if the operation overflows, or result otherwise. template typename std::enable_if::value && sizeof(T) * 8 <= 64, llvm::Optional>::type checkedOp(T LHS, T RHS, F Op, 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 (Overflow) return llvm::None; return Signed ? Out.getSExtValue() : Out.getZExtValue(); } } namespace llvm { /// Add two signed integers \p LHS and \p RHS. /// \return Optional of sum if no signed overflow occurred, /// \c None otherwise. template typename std::enable_if::value, llvm::Optional>::type checkedAdd(T LHS, T RHS) { return checkedOp(LHS, RHS, &llvm::APInt::sadd_ov); } /// Subtract two signed integers \p LHS and \p RHS. /// \return Optional of sum if no signed overflow occurred, /// \c None otherwise. template typename std::enable_if::value, llvm::Optional>::type checkedSub(T LHS, T RHS) { return checkedOp(LHS, RHS, &llvm::APInt::ssub_ov); } /// Multiply two signed integers \p LHS and \p RHS. /// \return Optional of product if no signed overflow occurred, /// \c None otherwise. template typename std::enable_if::value, llvm::Optional>::type checkedMul(T LHS, T RHS) { return checkedOp(LHS, RHS, &llvm::APInt::smul_ov); } /// Multiply A and B, and add C to the resulting product. /// \return Optional of result if no signed overflow occurred, /// \c None otherwise. template typename std::enable_if::value, llvm::Optional>::type checkedMulAdd(T A, T B, T C) { if (auto Product = checkedMul(A, B)) return checkedAdd(*Product, C); return llvm::None; } /// Add two unsigned integers \p LHS and \p RHS. /// \return Optional of sum if no unsigned overflow occurred, /// \c None otherwise. template typename std::enable_if::value, llvm::Optional>::type checkedAddUnsigned(T LHS, T RHS) { return checkedOp(LHS, RHS, &llvm::APInt::uadd_ov, /*Signed=*/false); } /// Multiply two unsigned integers \p LHS and \p RHS. /// \return Optional of product if no unsigned overflow occurred, /// \c None otherwise. template typename std::enable_if::value, llvm::Optional>::type checkedMulUnsigned(T LHS, T RHS) { return checkedOp(LHS, RHS, &llvm::APInt::umul_ov, /*Signed=*/false); } /// Multiply unsigned integers A and B, and add C to the resulting product. /// \return Optional of result if no unsigned overflow occurred, /// \c None otherwise. template typename std::enable_if::value, llvm::Optional>::type checkedMulAddUnsigned(T A, T B, T C) { if (auto Product = checkedMulUnsigned(A, B)) return checkedAddUnsigned(*Product, C); return llvm::None; } } // End llvm namespace #endif