| 1 | //===--- IncorrectRoundingsCheck.cpp - clang-tidy--------------------------===// |
|---|---|
| 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-exception |
| 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | |
| 9 | #include "IncorrectRoundingsCheck.h" |
| 10 | #include "clang/ASTMatchers/ASTMatchFinder.h" |
| 11 | #include "clang/ASTMatchers/ASTMatchers.h" |
| 12 | |
| 13 | using namespace clang::ast_matchers; |
| 14 | |
| 15 | namespace clang::tidy::bugprone { |
| 16 | |
| 17 | static llvm::APFloat getHalf(const llvm::fltSemantics &Semantics) { |
| 18 | return llvm::APFloat(Semantics, 1U) / llvm::APFloat(Semantics, 2U); |
| 19 | } |
| 20 | |
| 21 | namespace { |
| 22 | AST_MATCHER(FloatingLiteral, floatHalf) { |
| 23 | return Node.getValue() == getHalf(Semantics: Node.getSemantics()); |
| 24 | } |
| 25 | } // namespace |
| 26 | |
| 27 | void 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(InnerMatcher: realFloatingPointType())); |
| 33 | |
| 34 | // Find expressions of cast to int of the sum of a floating point expression |
| 35 | // and 0.5. |
| 36 | MatchFinder->addMatcher( |
| 37 | NodeMatch: traverse(TK: TK_AsIs, |
| 38 | InnerMatcher: implicitCastExpr( |
| 39 | hasImplicitDestinationType(InnerMatcher: isInteger()), |
| 40 | ignoringParenCasts(InnerMatcher: binaryOperator( |
| 41 | hasOperatorName(Name: "+"), hasOperands(Matcher1: FloatType, Matcher2: FloatType), |
| 42 | hasEitherOperand(InnerMatcher: ignoringParenImpCasts(InnerMatcher: FloatHalf))))) |
| 43 | .bind(ID: "CastExpr")), |
| 44 | Action: this); |
| 45 | } |
| 46 | |
| 47 | void IncorrectRoundingsCheck::check(const MatchFinder::MatchResult &Result) { |
| 48 | const auto *CastExpr = Result.Nodes.getNodeAs<ImplicitCastExpr>(ID: "CastExpr"); |
| 49 | diag(Loc: CastExpr->getBeginLoc(), |
| 50 | Description: "casting (double + 0.5) to integer leads to incorrect rounding; " |
| 51 | "consider using lround (#include <cmath>) instead"); |
| 52 | } |
| 53 | |
| 54 | } // namespace clang::tidy::bugprone |
| 55 |