| 1 | //===--- IncorrectRoundingsCheck.cpp - clang-tidy--------------------------===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | |
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| 9 | #include "IncorrectRoundingsCheck.h" |
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| 10 | #include "clang/ASTMatchers/ASTMatchFinder.h" |
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| 11 | #include "clang/ASTMatchers/ASTMatchers.h" |
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| 12 | |
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| 13 | using namespace clang::ast_matchers; |
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| 14 | |
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| 15 | namespace clang::tidy::bugprone { |
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| 16 | |
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| 17 | static llvm::APFloat getHalf(const llvm::fltSemantics &Semantics) { |
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| 18 | return llvm::APFloat(Semantics, 1U) / llvm::APFloat(Semantics, 2U); |
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| 19 | } |
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| 20 | |
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| 21 | namespace { |
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| 22 | AST_MATCHER(FloatingLiteral, floatHalf) { |
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| 23 | return Node.getValue() == getHalf(Semantics: Node.getSemantics()); |
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| 24 | } |
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| 25 | } // namespace |
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| 26 | |
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| 27 | void IncorrectRoundingsCheck::registerMatchers(MatchFinder *MatchFinder) { |
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| 28 | // Match a floating literal with value 0.5. |
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| 29 | auto FloatHalf = floatLiteral(floatHalf()); |
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| 30 | |
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| 31 | // Match a floating point expression. |
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| 32 | auto FloatType = expr(hasType(InnerMatcher: realFloatingPointType())); |
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| 33 | |
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| 34 | // Find expressions of cast to int of the sum of a floating point expression |
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| 35 | // and 0.5. |
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| 36 | MatchFinder->addMatcher( |
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| 37 | NodeMatch: traverse(TK: TK_AsIs, |
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| 38 | InnerMatcher: implicitCastExpr( |
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| 39 | hasImplicitDestinationType(InnerMatcher: isInteger()), |
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| 40 | ignoringParenCasts(InnerMatcher: binaryOperator( |
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| 41 | hasOperatorName(Name: "+" ), hasOperands(Matcher1: FloatType, Matcher2: FloatType), |
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| 42 | hasEitherOperand(InnerMatcher: ignoringParenImpCasts(InnerMatcher: FloatHalf))))) |
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| 43 | .bind(ID: "CastExpr" )), |
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| 44 | Action: this); |
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| 45 | } |
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| 46 | |
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| 47 | void IncorrectRoundingsCheck::check(const MatchFinder::MatchResult &Result) { |
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| 48 | const auto *CastExpr = Result.Nodes.getNodeAs<ImplicitCastExpr>(ID: "CastExpr" ); |
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| 49 | diag(Loc: CastExpr->getBeginLoc(), |
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| 50 | Description: "casting (double + 0.5) to integer leads to incorrect rounding; " |
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| 51 | "consider using lround (#include <cmath>) instead" ); |
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| 52 | } |
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| 53 | |
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| 54 | } // namespace clang::tidy::bugprone |
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| 55 | |
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