6024e5c395
clang 20.0.0 (based on r547379) from build 12806354. Bug: http://b/379133546 Test: N/A Change-Id: I2eb8938af55d809de674be63cb30cf27e801862b Upstream-Commit: ad834e67b1105d15ef907f6255d4c96e8e733f57
112 lines
3.9 KiB
C++
112 lines
3.9 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 <optional>
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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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std::enable_if_t<std::is_integral_v<T> && sizeof(T) * 8 <= 64, std::optional<T>>
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checkedOp(T LHS, T RHS, F Op, bool Signed = true) {
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llvm::APInt ALHS(sizeof(T) * 8, LHS, Signed);
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llvm::APInt ARHS(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 std::nullopt;
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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 std::nullopt otherwise.
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template <typename T>
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std::enable_if_t<std::is_signed_v<T>, std::optional<T>> checkedAdd(T LHS,
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T RHS) {
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return checkedOp(LHS, RHS, &llvm::APInt::sadd_ov);
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}
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/// Subtract 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 std::nullopt otherwise.
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template <typename T>
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std::enable_if_t<std::is_signed_v<T>, std::optional<T>> checkedSub(T LHS,
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T RHS) {
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return checkedOp(LHS, RHS, &llvm::APInt::ssub_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 std::nullopt otherwise.
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template <typename T>
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std::enable_if_t<std::is_signed_v<T>, std::optional<T>> checkedMul(T LHS,
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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 std::nullopt otherwise.
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template <typename T>
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std::enable_if_t<std::is_signed_v<T>, std::optional<T>> checkedMulAdd(T A, T B,
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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 std::nullopt;
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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 std::nullopt otherwise.
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template <typename T>
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std::enable_if_t<std::is_unsigned_v<T>, std::optional<T>>
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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 std::nullopt otherwise.
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template <typename T>
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std::enable_if_t<std::is_unsigned_v<T>, std::optional<T>>
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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 std::nullopt otherwise.
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template <typename T>
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std::enable_if_t<std::is_unsigned_v<T>, std::optional<T>>
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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 std::nullopt;
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}
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} // End llvm namespace
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#endif
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