forked from OSchip/llvm-project
71 lines
2.5 KiB
C++
71 lines
2.5 KiB
C++
//===--- IncorrectRoundingsCheck.cpp - clang-tidy ------------------------------===//
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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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#include "IncorrectRoundingsCheck.h"
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#include "clang/AST/DeclBase.h"
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#include "clang/AST/Type.h"
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#include "clang/ASTMatchers/ASTMatchFinder.h"
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#include "clang/ASTMatchers/ASTMatchers.h"
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#include "clang/Lex/Lexer.h"
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using namespace clang::ast_matchers;
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namespace clang {
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namespace tidy {
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namespace bugprone {
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namespace {
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AST_MATCHER(FloatingLiteral, floatHalf) {
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const auto &literal = Node.getValue();
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if ((&Node.getSemantics()) == &llvm::APFloat::IEEEsingle())
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return literal.convertToFloat() == 0.5f;
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if ((&Node.getSemantics()) == &llvm::APFloat::IEEEdouble())
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return literal.convertToDouble() == 0.5;
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return false;
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}
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} // namespace
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void IncorrectRoundingsCheck::registerMatchers(MatchFinder *MatchFinder) {
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// Match a floating literal with value 0.5.
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auto FloatHalf = floatLiteral(floatHalf());
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// Match a floating point expression.
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auto FloatType = expr(hasType(realFloatingPointType()));
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// Match a floating literal of 0.5 or a floating literal of 0.5 implicitly.
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// cast to floating type.
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auto FloatOrCastHalf =
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anyOf(FloatHalf,
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implicitCastExpr(FloatType, has(ignoringParenImpCasts(FloatHalf))));
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// Match if either the LHS or RHS is a floating literal of 0.5 or a floating
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// literal of 0.5 and the other is of type double or vice versa.
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auto OneSideHalf = anyOf(allOf(hasLHS(FloatOrCastHalf), hasRHS(FloatType)),
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allOf(hasRHS(FloatOrCastHalf), hasLHS(FloatType)));
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// Find expressions of cast to int of the sum of a floating point expression
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// and 0.5.
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MatchFinder->addMatcher(
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implicitCastExpr(
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hasImplicitDestinationType(isInteger()),
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ignoringParenCasts(binaryOperator(hasOperatorName("+"), OneSideHalf)))
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.bind("CastExpr"),
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this);
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}
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void IncorrectRoundingsCheck::check(const MatchFinder::MatchResult &Result) {
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const auto *CastExpr = Result.Nodes.getNodeAs<ImplicitCastExpr>("CastExpr");
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diag(CastExpr->getBeginLoc(),
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"casting (double + 0.5) to integer leads to incorrect rounding; "
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"consider using lround (#include <cmath>) instead");
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}
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} // namespace bugprone
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} // namespace tidy
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} // namespace clang
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