1 //===--- FunctionSize.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 "FunctionSizeCheck.h" 11 #include "clang/AST/RecursiveASTVisitor.h" 12 #include "clang/ASTMatchers/ASTMatchFinder.h" 13 14 using namespace clang::ast_matchers; 15 16 namespace clang { 17 namespace tidy { 18 namespace readability { 19 20 class FunctionASTVisitor : public RecursiveASTVisitor<FunctionASTVisitor> { 21 using Base = RecursiveASTVisitor<FunctionASTVisitor>; 22 23 public: 24 bool TraverseStmt(Stmt *Node) { 25 if (!Node) 26 return Base::TraverseStmt(Node); 27 28 if (TrackedParent.back() && !isa<CompoundStmt>(Node)) 29 ++Info.Statements; 30 31 switch (Node->getStmtClass()) { 32 case Stmt::IfStmtClass: 33 case Stmt::WhileStmtClass: 34 case Stmt::DoStmtClass: 35 case Stmt::CXXForRangeStmtClass: 36 case Stmt::ForStmtClass: 37 case Stmt::SwitchStmtClass: 38 ++Info.Branches; 39 // fallthrough 40 case Stmt::CompoundStmtClass: 41 // If this new compound statement is located in a compound statement, 42 // which is already nested NestingThreshold levels deep, record the start 43 // location of this new compound statement 44 if (CurrentNestingLevel == Info.NestingThreshold) 45 Info.NestingThresholders.push_back(Node->getLocStart()); 46 47 ++CurrentNestingLevel; 48 TrackedParent.push_back(true); 49 break; 50 default: 51 TrackedParent.push_back(false); 52 break; 53 } 54 55 Base::TraverseStmt(Node); 56 57 if (TrackedParent.back()) 58 --CurrentNestingLevel; 59 TrackedParent.pop_back(); 60 61 return true; 62 } 63 64 bool TraverseDecl(Decl *Node) { 65 TrackedParent.push_back(false); 66 Base::TraverseDecl(Node); 67 TrackedParent.pop_back(); 68 return true; 69 } 70 71 struct FunctionInfo { 72 unsigned Lines = 0; 73 unsigned Statements = 0; 74 unsigned Branches = 0; 75 unsigned NestingThreshold = 0; 76 std::vector<SourceLocation> NestingThresholders; 77 }; 78 FunctionInfo Info; 79 std::vector<bool> TrackedParent; 80 unsigned CurrentNestingLevel = 0; 81 }; 82 83 FunctionSizeCheck::FunctionSizeCheck(StringRef Name, ClangTidyContext *Context) 84 : ClangTidyCheck(Name, Context), 85 LineThreshold(Options.get("LineThreshold", -1U)), 86 StatementThreshold(Options.get("StatementThreshold", 800U)), 87 BranchThreshold(Options.get("BranchThreshold", -1U)), 88 ParameterThreshold(Options.get("ParameterThreshold", -1U)), 89 NestingThreshold(Options.get("NestingThreshold", -1U)) {} 90 91 void FunctionSizeCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) { 92 Options.store(Opts, "LineThreshold", LineThreshold); 93 Options.store(Opts, "StatementThreshold", StatementThreshold); 94 Options.store(Opts, "BranchThreshold", BranchThreshold); 95 Options.store(Opts, "ParameterThreshold", ParameterThreshold); 96 Options.store(Opts, "NestingThreshold", NestingThreshold); 97 } 98 99 void FunctionSizeCheck::registerMatchers(MatchFinder *Finder) { 100 Finder->addMatcher(functionDecl(unless(isInstantiated())).bind("func"), this); 101 } 102 103 void FunctionSizeCheck::check(const MatchFinder::MatchResult &Result) { 104 const auto *Func = Result.Nodes.getNodeAs<FunctionDecl>("func"); 105 106 FunctionASTVisitor Visitor; 107 Visitor.Info.NestingThreshold = NestingThreshold; 108 Visitor.TraverseDecl(const_cast<FunctionDecl *>(Func)); 109 auto &FI = Visitor.Info; 110 111 if (FI.Statements == 0) 112 return; 113 114 // Count the lines including whitespace and comments. Really simple. 115 if (const Stmt *Body = Func->getBody()) { 116 SourceManager *SM = Result.SourceManager; 117 if (SM->isWrittenInSameFile(Body->getLocStart(), Body->getLocEnd())) { 118 FI.Lines = SM->getSpellingLineNumber(Body->getLocEnd()) - 119 SM->getSpellingLineNumber(Body->getLocStart()); 120 } 121 } 122 123 unsigned ActualNumberParameters = Func->getNumParams(); 124 125 if (FI.Lines > LineThreshold || FI.Statements > StatementThreshold || 126 FI.Branches > BranchThreshold || 127 ActualNumberParameters > ParameterThreshold || 128 !FI.NestingThresholders.empty()) { 129 diag(Func->getLocation(), 130 "function %0 exceeds recommended size/complexity thresholds") 131 << Func; 132 } 133 134 if (FI.Lines > LineThreshold) { 135 diag(Func->getLocation(), 136 "%0 lines including whitespace and comments (threshold %1)", 137 DiagnosticIDs::Note) 138 << FI.Lines << LineThreshold; 139 } 140 141 if (FI.Statements > StatementThreshold) { 142 diag(Func->getLocation(), "%0 statements (threshold %1)", 143 DiagnosticIDs::Note) 144 << FI.Statements << StatementThreshold; 145 } 146 147 if (FI.Branches > BranchThreshold) { 148 diag(Func->getLocation(), "%0 branches (threshold %1)", DiagnosticIDs::Note) 149 << FI.Branches << BranchThreshold; 150 } 151 152 if (ActualNumberParameters > ParameterThreshold) { 153 diag(Func->getLocation(), "%0 parameters (threshold %1)", 154 DiagnosticIDs::Note) 155 << ActualNumberParameters << ParameterThreshold; 156 } 157 158 for (const auto &CSPos : FI.NestingThresholders) { 159 diag(CSPos, "nesting level %0 starts here (threshold %1)", 160 DiagnosticIDs::Note) 161 << NestingThreshold + 1 << NestingThreshold; 162 } 163 } 164 165 } // namespace readability 166 } // namespace tidy 167 } // namespace clang 168