clang-tools 6.0.0

IncorrectRoundings.cpp
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1 //===--- IncorrectRoundings.cpp - clang-tidy ------------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9
10 #include "IncorrectRoundings.h"
11 #include "clang/AST/DeclBase.h"
12 #include "clang/AST/Type.h"
13 #include "clang/ASTMatchers/ASTMatchFinder.h"
14 #include "clang/ASTMatchers/ASTMatchers.h"
15 #include "clang/Lex/Lexer.h"
16
17 using namespace clang::ast_matchers;
18
19 namespace clang {
20 namespace tidy {
21 namespace misc {
22
23 namespace {
24 AST_MATCHER(FloatingLiteral, floatHalf) {
25 const auto &literal = Node.getValue();
26 if ((&Node.getSemantics()) == &llvm::APFloat::IEEEsingle())
27 return literal.convertToFloat() == 0.5f;
28 if ((&Node.getSemantics()) == &llvm::APFloat::IEEEdouble())
29 return literal.convertToDouble() == 0.5;
30 return false;
31 }
32 } // namespace
33
34 void IncorrectRoundings::registerMatchers(MatchFinder *MatchFinder) {
35 // Match a floating literal with value 0.5.
36 auto FloatHalf = floatLiteral(floatHalf());
37
38 // Match a floating point expression.
39 auto FloatType = expr(hasType(realFloatingPointType()));
40
41 // Match a floating literal of 0.5 or a floating literal of 0.5 implicitly.
42 // cast to floating type.
43 auto FloatOrCastHalf =
44 anyOf(FloatHalf,
45 implicitCastExpr(FloatType, has(ignoringParenImpCasts(FloatHalf))));
46
47 // Match if either the LHS or RHS is a floating literal of 0.5 or a floating
48 // literal of 0.5 and the other is of type double or vice versa.
49 auto OneSideHalf = anyOf(allOf(hasLHS(FloatOrCastHalf), hasRHS(FloatType)),
50 allOf(hasRHS(FloatOrCastHalf), hasLHS(FloatType)));
51
52 // Find expressions of cast to int of the sum of a floating point expression
53 // and 0.5.
54 MatchFinder->addMatcher(
55 implicitCastExpr(
56 hasImplicitDestinationType(isInteger()),
57 ignoringParenCasts(binaryOperator(hasOperatorName("+"), OneSideHalf)))
58 .bind("CastExpr"),
59 this);
60 }
61
62 void IncorrectRoundings::check(const MatchFinder::MatchResult &Result) {
63 const auto *CastExpr = Result.Nodes.getNodeAs<ImplicitCastExpr>("CastExpr");
64 diag(CastExpr->getLocStart(),
65 "casting (double + 0.5) to integer leads to incorrect rounding; "
66 "consider using lround (#include <cmath>) instead");
67 }
68
69 } // namespace misc
70 } // namespace tidy
71 } // namespace clang
clang::ast_matchers
Definition: ClangTidyDiagnosticConsumer.h:27
IncorrectRoundings.h
clang
Definition: AndroidTidyModule.cpp:28
clang::ast_matchers::AST_MATCHER
AST_MATCHER(VarDecl, isAsm)
Definition: NoAssemblerCheck.cpp:18