55 lines · cpp
1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#include "IncorrectRoundingsCheck.h"10#include "clang/ASTMatchers/ASTMatchFinder.h"11#include "clang/ASTMatchers/ASTMatchers.h"12 13using namespace clang::ast_matchers;14 15namespace clang::tidy::bugprone {16 17static llvm::APFloat getHalf(const llvm::fltSemantics &Semantics) {18 return llvm::APFloat(Semantics, 1U) / llvm::APFloat(Semantics, 2U);19}20 21namespace {22AST_MATCHER(FloatingLiteral, floatHalf) {23 return Node.getValue() == getHalf(Node.getSemantics());24}25} // namespace26 27void IncorrectRoundingsCheck::registerMatchers(MatchFinder *MatchFinder) {28 // Match a floating literal with value 0.5.29 auto FloatHalf = floatLiteral(floatHalf());30 31 // Match a floating point expression.32 auto FloatType = expr(hasType(realFloatingPointType()));33 34 // Find expressions of cast to int of the sum of a floating point expression35 // and 0.5.36 MatchFinder->addMatcher(37 traverse(TK_AsIs,38 implicitCastExpr(39 hasImplicitDestinationType(isInteger()),40 ignoringParenCasts(binaryOperator(41 hasOperatorName("+"), hasOperands(FloatType, FloatType),42 hasEitherOperand(ignoringParenImpCasts(FloatHalf)))))43 .bind("CastExpr")),44 this);45}46 47void IncorrectRoundingsCheck::check(const MatchFinder::MatchResult &Result) {48 const auto *CastExpr = Result.Nodes.getNodeAs<ImplicitCastExpr>("CastExpr");49 diag(CastExpr->getBeginLoc(),50 "casting (double + 0.5) to integer leads to incorrect rounding; "51 "consider using lround (#include <cmath>) instead");52}53 54} // namespace clang::tidy::bugprone55