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to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@351636 91177308-0d34-0410-b5e6-96231b3b80d8
104 lines
3.5 KiB
C++
104 lines
3.5 KiB
C++
//==-- llvm/Support/CheckedArithmetic.h - Safe arithmetical operations *- C++ //
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains generic functions for operating on integers which
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// give the indication on whether the operation has overflown.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_CHECKEDARITHMETIC_H
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#define LLVM_SUPPORT_CHECKEDARITHMETIC_H
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#include "llvm/ADT/APInt.h"
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#include "llvm/ADT/Optional.h"
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#include <type_traits>
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namespace {
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/// Utility function to apply a given method of \c APInt \p F to \p LHS and
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/// \p RHS.
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/// \return Empty optional if the operation overflows, or result otherwise.
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template <typename T, typename F>
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typename std::enable_if<std::is_integral<T>::value && sizeof(T) * 8 <= 64,
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llvm::Optional<T>>::type
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checkedOp(T LHS, T RHS, F Op, bool Signed = true) {
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llvm::APInt ALHS(/*BitSize=*/sizeof(T) * 8, LHS, Signed);
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llvm::APInt ARHS(/*BitSize=*/sizeof(T) * 8, RHS, Signed);
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bool Overflow;
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llvm::APInt Out = (ALHS.*Op)(ARHS, Overflow);
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if (Overflow)
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return llvm::None;
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return Signed ? Out.getSExtValue() : Out.getZExtValue();
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}
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}
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namespace llvm {
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/// Add two signed integers \p LHS and \p RHS.
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/// \return Optional of sum if no signed overflow occurred,
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/// \c None otherwise.
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template <typename T>
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typename std::enable_if<std::is_signed<T>::value, llvm::Optional<T>>::type
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checkedAdd(T LHS, T RHS) {
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return checkedOp(LHS, RHS, &llvm::APInt::sadd_ov);
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}
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/// Multiply two signed integers \p LHS and \p RHS.
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/// \return Optional of product if no signed overflow occurred,
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/// \c None otherwise.
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template <typename T>
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typename std::enable_if<std::is_signed<T>::value, llvm::Optional<T>>::type
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checkedMul(T LHS, T RHS) {
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return checkedOp(LHS, RHS, &llvm::APInt::smul_ov);
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}
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/// Multiply A and B, and add C to the resulting product.
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/// \return Optional of result if no signed overflow occurred,
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/// \c None otherwise.
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template <typename T>
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typename std::enable_if<std::is_signed<T>::value, llvm::Optional<T>>::type
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checkedMulAdd(T A, T B, T C) {
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if (auto Product = checkedMul(A, B))
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return checkedAdd(*Product, C);
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return llvm::None;
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}
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/// Add two unsigned integers \p LHS and \p RHS.
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/// \return Optional of sum if no unsigned overflow occurred,
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/// \c None otherwise.
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template <typename T>
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typename std::enable_if<std::is_unsigned<T>::value, llvm::Optional<T>>::type
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checkedAddUnsigned(T LHS, T RHS) {
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return checkedOp(LHS, RHS, &llvm::APInt::uadd_ov, /*Signed=*/false);
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}
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/// Multiply two unsigned integers \p LHS and \p RHS.
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/// \return Optional of product if no unsigned overflow occurred,
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/// \c None otherwise.
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template <typename T>
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typename std::enable_if<std::is_unsigned<T>::value, llvm::Optional<T>>::type
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checkedMulUnsigned(T LHS, T RHS) {
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return checkedOp(LHS, RHS, &llvm::APInt::umul_ov, /*Signed=*/false);
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}
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/// Multiply unsigned integers A and B, and add C to the resulting product.
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/// \return Optional of result if no unsigned overflow occurred,
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/// \c None otherwise.
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template <typename T>
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typename std::enable_if<std::is_unsigned<T>::value, llvm::Optional<T>>::type
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checkedMulAddUnsigned(T A, T B, T C) {
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if (auto Product = checkedMulUnsigned(A, B))
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return checkedAddUnsigned(*Product, C);
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return llvm::None;
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}
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} // End llvm namespace
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#endif
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