| //===--- CloneDetection.cpp - Finds code clones in an AST -------*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| /// |
| /// This file implements classes for searching and anlyzing source code clones. |
| /// |
| //===----------------------------------------------------------------------===// |
| |
| #include "clang/Analysis/CloneDetection.h" |
| |
| #include "clang/AST/ASTContext.h" |
| #include "clang/AST/RecursiveASTVisitor.h" |
| #include "clang/AST/Stmt.h" |
| #include "clang/AST/StmtVisitor.h" |
| #include "clang/Lex/Lexer.h" |
| #include "llvm/ADT/StringRef.h" |
| #include "llvm/Support/MD5.h" |
| #include "llvm/Support/raw_ostream.h" |
| |
| using namespace clang; |
| |
| StmtSequence::StmtSequence(const CompoundStmt *Stmt, const Decl *D, |
| unsigned StartIndex, unsigned EndIndex) |
| : S(Stmt), D(D), StartIndex(StartIndex), EndIndex(EndIndex) { |
| assert(Stmt && "Stmt must not be a nullptr"); |
| assert(StartIndex < EndIndex && "Given array should not be empty"); |
| assert(EndIndex <= Stmt->size() && "Given array too big for this Stmt"); |
| } |
| |
| StmtSequence::StmtSequence(const Stmt *Stmt, const Decl *D) |
| : S(Stmt), D(D), StartIndex(0), EndIndex(0) {} |
| |
| StmtSequence::StmtSequence() |
| : S(nullptr), D(nullptr), StartIndex(0), EndIndex(0) {} |
| |
| bool StmtSequence::contains(const StmtSequence &Other) const { |
| // If both sequences reside in different declarations, they can never contain |
| // each other. |
| if (D != Other.D) |
| return false; |
| |
| const SourceManager &SM = getASTContext().getSourceManager(); |
| |
| // Otherwise check if the start and end locations of the current sequence |
| // surround the other sequence. |
| bool StartIsInBounds = |
| SM.isBeforeInTranslationUnit(getStartLoc(), Other.getStartLoc()) || |
| getStartLoc() == Other.getStartLoc(); |
| if (!StartIsInBounds) |
| return false; |
| |
| bool EndIsInBounds = |
| SM.isBeforeInTranslationUnit(Other.getEndLoc(), getEndLoc()) || |
| Other.getEndLoc() == getEndLoc(); |
| return EndIsInBounds; |
| } |
| |
| StmtSequence::iterator StmtSequence::begin() const { |
| if (!holdsSequence()) { |
| return &S; |
| } |
| auto CS = cast<CompoundStmt>(S); |
| return CS->body_begin() + StartIndex; |
| } |
| |
| StmtSequence::iterator StmtSequence::end() const { |
| if (!holdsSequence()) { |
| return reinterpret_cast<StmtSequence::iterator>(&S) + 1; |
| } |
| auto CS = cast<CompoundStmt>(S); |
| return CS->body_begin() + EndIndex; |
| } |
| |
| ASTContext &StmtSequence::getASTContext() const { |
| assert(D); |
| return D->getASTContext(); |
| } |
| |
| SourceLocation StmtSequence::getStartLoc() const { |
| return front()->getLocStart(); |
| } |
| |
| SourceLocation StmtSequence::getEndLoc() const { return back()->getLocEnd(); } |
| |
| SourceRange StmtSequence::getSourceRange() const { |
| return SourceRange(getStartLoc(), getEndLoc()); |
| } |
| |
| /// Prints the macro name that contains the given SourceLocation into the given |
| /// raw_string_ostream. |
| static void printMacroName(llvm::raw_string_ostream &MacroStack, |
| ASTContext &Context, SourceLocation Loc) { |
| MacroStack << Lexer::getImmediateMacroName(Loc, Context.getSourceManager(), |
| Context.getLangOpts()); |
| |
| // Add an empty space at the end as a padding to prevent |
| // that macro names concatenate to the names of other macros. |
| MacroStack << " "; |
| } |
| |
| /// Returns a string that represents all macro expansions that expanded into the |
| /// given SourceLocation. |
| /// |
| /// If 'getMacroStack(A) == getMacroStack(B)' is true, then the SourceLocations |
| /// A and B are expanded from the same macros in the same order. |
| static std::string getMacroStack(SourceLocation Loc, ASTContext &Context) { |
| std::string MacroStack; |
| llvm::raw_string_ostream MacroStackStream(MacroStack); |
| SourceManager &SM = Context.getSourceManager(); |
| |
| // Iterate over all macros that expanded into the given SourceLocation. |
| while (Loc.isMacroID()) { |
| // Add the macro name to the stream. |
| printMacroName(MacroStackStream, Context, Loc); |
| Loc = SM.getImmediateMacroCallerLoc(Loc); |
| } |
| MacroStackStream.flush(); |
| return MacroStack; |
| } |
| |
| namespace { |
| typedef unsigned DataPiece; |
| |
| /// Collects the data of a single Stmt. |
| /// |
| /// This class defines what a code clone is: If it collects for two statements |
| /// the same data, then those two statements are considered to be clones of each |
| /// other. |
| /// |
| /// All collected data is forwarded to the given data consumer of the type T. |
| /// The data consumer class needs to provide a member method with the signature: |
| /// update(StringRef Str) |
| template <typename T> |
| class StmtDataCollector : public ConstStmtVisitor<StmtDataCollector<T>> { |
| |
| ASTContext &Context; |
| /// The data sink to which all data is forwarded. |
| T &DataConsumer; |
| |
| public: |
| /// Collects data of the given Stmt. |
| /// \param S The given statement. |
| /// \param Context The ASTContext of S. |
| /// \param DataConsumer The data sink to which all data is forwarded. |
| StmtDataCollector(const Stmt *S, ASTContext &Context, T &DataConsumer) |
| : Context(Context), DataConsumer(DataConsumer) { |
| this->Visit(S); |
| } |
| |
| // Below are utility methods for appending different data to the vector. |
| |
| void addData(DataPiece Integer) { |
| DataConsumer.update( |
| StringRef(reinterpret_cast<char *>(&Integer), sizeof(Integer))); |
| } |
| |
| void addData(llvm::StringRef Str) { DataConsumer.update(Str); } |
| |
| void addData(const QualType &QT) { addData(QT.getAsString()); } |
| |
| // The functions below collect the class specific data of each Stmt subclass. |
| |
| // Utility macro for defining a visit method for a given class. This method |
| // calls back to the ConstStmtVisitor to visit all parent classes. |
| #define DEF_ADD_DATA(CLASS, CODE) \ |
| void Visit##CLASS(const CLASS *S) { \ |
| CODE; \ |
| ConstStmtVisitor<StmtDataCollector>::Visit##CLASS(S); \ |
| } |
| |
| DEF_ADD_DATA(Stmt, { |
| addData(S->getStmtClass()); |
| // This ensures that macro generated code isn't identical to macro-generated |
| // code. |
| addData(getMacroStack(S->getLocStart(), Context)); |
| addData(getMacroStack(S->getLocEnd(), Context)); |
| }) |
| DEF_ADD_DATA(Expr, { addData(S->getType()); }) |
| |
| //--- Builtin functionality ----------------------------------------------// |
| DEF_ADD_DATA(ArrayTypeTraitExpr, { addData(S->getTrait()); }) |
| DEF_ADD_DATA(ExpressionTraitExpr, { addData(S->getTrait()); }) |
| DEF_ADD_DATA(PredefinedExpr, { addData(S->getIdentType()); }) |
| DEF_ADD_DATA(TypeTraitExpr, { |
| addData(S->getTrait()); |
| for (unsigned i = 0; i < S->getNumArgs(); ++i) |
| addData(S->getArg(i)->getType()); |
| }) |
| |
| //--- Calls --------------------------------------------------------------// |
| DEF_ADD_DATA(CallExpr, { |
| // Function pointers don't have a callee and we just skip hashing it. |
| if (const FunctionDecl *D = S->getDirectCallee()) { |
| // If the function is a template specialization, we also need to handle |
| // the template arguments as they are not included in the qualified name. |
| if (auto Args = D->getTemplateSpecializationArgs()) { |
| std::string ArgString; |
| |
| // Print all template arguments into ArgString |
| llvm::raw_string_ostream OS(ArgString); |
| for (unsigned i = 0; i < Args->size(); ++i) { |
| Args->get(i).print(Context.getLangOpts(), OS); |
| // Add a padding character so that 'foo<X, XX>()' != 'foo<XX, X>()'. |
| OS << '\n'; |
| } |
| OS.flush(); |
| |
| addData(ArgString); |
| } |
| addData(D->getQualifiedNameAsString()); |
| } |
| }) |
| |
| //--- Exceptions ---------------------------------------------------------// |
| DEF_ADD_DATA(CXXCatchStmt, { addData(S->getCaughtType()); }) |
| |
| //--- C++ OOP Stmts ------------------------------------------------------// |
| DEF_ADD_DATA(CXXDeleteExpr, { |
| addData(S->isArrayFormAsWritten()); |
| addData(S->isGlobalDelete()); |
| }) |
| |
| //--- Casts --------------------------------------------------------------// |
| DEF_ADD_DATA(ObjCBridgedCastExpr, { addData(S->getBridgeKind()); }) |
| |
| //--- Miscellaneous Exprs ------------------------------------------------// |
| DEF_ADD_DATA(BinaryOperator, { addData(S->getOpcode()); }) |
| DEF_ADD_DATA(UnaryOperator, { addData(S->getOpcode()); }) |
| |
| //--- Control flow -------------------------------------------------------// |
| DEF_ADD_DATA(GotoStmt, { addData(S->getLabel()->getName()); }) |
| DEF_ADD_DATA(IndirectGotoStmt, { |
| if (S->getConstantTarget()) |
| addData(S->getConstantTarget()->getName()); |
| }) |
| DEF_ADD_DATA(LabelStmt, { addData(S->getDecl()->getName()); }) |
| DEF_ADD_DATA(MSDependentExistsStmt, { addData(S->isIfExists()); }) |
| DEF_ADD_DATA(AddrLabelExpr, { addData(S->getLabel()->getName()); }) |
| |
| //--- Objective-C --------------------------------------------------------// |
| DEF_ADD_DATA(ObjCIndirectCopyRestoreExpr, { addData(S->shouldCopy()); }) |
| DEF_ADD_DATA(ObjCPropertyRefExpr, { |
| addData(S->isSuperReceiver()); |
| addData(S->isImplicitProperty()); |
| }) |
| DEF_ADD_DATA(ObjCAtCatchStmt, { addData(S->hasEllipsis()); }) |
| |
| //--- Miscellaneous Stmts ------------------------------------------------// |
| DEF_ADD_DATA(CXXFoldExpr, { |
| addData(S->isRightFold()); |
| addData(S->getOperator()); |
| }) |
| DEF_ADD_DATA(GenericSelectionExpr, { |
| for (unsigned i = 0; i < S->getNumAssocs(); ++i) { |
| addData(S->getAssocType(i)); |
| } |
| }) |
| DEF_ADD_DATA(LambdaExpr, { |
| for (const LambdaCapture &C : S->captures()) { |
| addData(C.isPackExpansion()); |
| addData(C.getCaptureKind()); |
| if (C.capturesVariable()) |
| addData(C.getCapturedVar()->getType()); |
| } |
| addData(S->isGenericLambda()); |
| addData(S->isMutable()); |
| }) |
| DEF_ADD_DATA(DeclStmt, { |
| auto numDecls = std::distance(S->decl_begin(), S->decl_end()); |
| addData(static_cast<DataPiece>(numDecls)); |
| for (const Decl *D : S->decls()) { |
| if (const VarDecl *VD = dyn_cast<VarDecl>(D)) { |
| addData(VD->getType()); |
| } |
| } |
| }) |
| DEF_ADD_DATA(AsmStmt, { |
| addData(S->isSimple()); |
| addData(S->isVolatile()); |
| addData(S->generateAsmString(Context)); |
| for (unsigned i = 0; i < S->getNumInputs(); ++i) { |
| addData(S->getInputConstraint(i)); |
| } |
| for (unsigned i = 0; i < S->getNumOutputs(); ++i) { |
| addData(S->getOutputConstraint(i)); |
| } |
| for (unsigned i = 0; i < S->getNumClobbers(); ++i) { |
| addData(S->getClobber(i)); |
| } |
| }) |
| DEF_ADD_DATA(AttributedStmt, { |
| for (const Attr *A : S->getAttrs()) { |
| addData(std::string(A->getSpelling())); |
| } |
| }) |
| }; |
| } // end anonymous namespace |
| |
| void CloneDetector::analyzeCodeBody(const Decl *D) { |
| assert(D); |
| assert(D->hasBody()); |
| |
| Sequences.push_back(StmtSequence(D->getBody(), D)); |
| } |
| |
| /// Returns true if and only if \p Stmt contains at least one other |
| /// sequence in the \p Group. |
| static bool containsAnyInGroup(StmtSequence &Seq, |
| CloneDetector::CloneGroup &Group) { |
| for (StmtSequence &GroupSeq : Group) { |
| if (Seq.contains(GroupSeq)) |
| return true; |
| } |
| return false; |
| } |
| |
| /// Returns true if and only if all sequences in \p OtherGroup are |
| /// contained by a sequence in \p Group. |
| static bool containsGroup(CloneDetector::CloneGroup &Group, |
| CloneDetector::CloneGroup &OtherGroup) { |
| // We have less sequences in the current group than we have in the other, |
| // so we will never fulfill the requirement for returning true. This is only |
| // possible because we know that a sequence in Group can contain at most |
| // one sequence in OtherGroup. |
| if (Group.size() < OtherGroup.size()) |
| return false; |
| |
| for (StmtSequence &Stmt : Group) { |
| if (!containsAnyInGroup(Stmt, OtherGroup)) |
| return false; |
| } |
| return true; |
| } |
| |
| void OnlyLargestCloneConstraint::constrain( |
| std::vector<CloneDetector::CloneGroup> &Result) { |
| std::vector<unsigned> IndexesToRemove; |
| |
| // Compare every group in the result with the rest. If one groups contains |
| // another group, we only need to return the bigger group. |
| // Note: This doesn't scale well, so if possible avoid calling any heavy |
| // function from this loop to minimize the performance impact. |
| for (unsigned i = 0; i < Result.size(); ++i) { |
| for (unsigned j = 0; j < Result.size(); ++j) { |
| // Don't compare a group with itself. |
| if (i == j) |
| continue; |
| |
| if (containsGroup(Result[j], Result[i])) { |
| IndexesToRemove.push_back(i); |
| break; |
| } |
| } |
| } |
| |
| // Erasing a list of indexes from the vector should be done with decreasing |
| // indexes. As IndexesToRemove is constructed with increasing values, we just |
| // reverse iterate over it to get the desired order. |
| for (auto I = IndexesToRemove.rbegin(); I != IndexesToRemove.rend(); ++I) { |
| Result.erase(Result.begin() + *I); |
| } |
| } |
| |
| static size_t createHash(llvm::MD5 &Hash) { |
| size_t HashCode; |
| |
| // Create the final hash code for the current Stmt. |
| llvm::MD5::MD5Result HashResult; |
| Hash.final(HashResult); |
| |
| // Copy as much as possible of the generated hash code to the Stmt's hash |
| // code. |
| std::memcpy(&HashCode, &HashResult, |
| std::min(sizeof(HashCode), sizeof(HashResult))); |
| |
| return HashCode; |
| } |
| |
| size_t RecursiveCloneTypeIIConstraint::saveHash( |
| const Stmt *S, const Decl *D, |
| std::vector<std::pair<size_t, StmtSequence>> &StmtsByHash) { |
| llvm::MD5 Hash; |
| ASTContext &Context = D->getASTContext(); |
| |
| StmtDataCollector<llvm::MD5>(S, Context, Hash); |
| |
| auto CS = dyn_cast<CompoundStmt>(S); |
| SmallVector<size_t, 8> ChildHashes; |
| |
| for (const Stmt *Child : S->children()) { |
| if (Child == nullptr) { |
| ChildHashes.push_back(0); |
| continue; |
| } |
| size_t ChildHash = saveHash(Child, D, StmtsByHash); |
| Hash.update( |
| StringRef(reinterpret_cast<char *>(&ChildHash), sizeof(ChildHash))); |
| ChildHashes.push_back(ChildHash); |
| } |
| |
| if (CS) { |
| for (unsigned Length = 2; Length <= CS->size(); ++Length) { |
| for (unsigned Pos = 0; Pos <= CS->size() - Length; ++Pos) { |
| llvm::MD5 Hash; |
| for (unsigned i = Pos; i < Pos + Length; ++i) { |
| size_t ChildHash = ChildHashes[i]; |
| Hash.update(StringRef(reinterpret_cast<char *>(&ChildHash), |
| sizeof(ChildHash))); |
| } |
| StmtsByHash.push_back(std::make_pair( |
| createHash(Hash), StmtSequence(CS, D, Pos, Pos + Length))); |
| } |
| } |
| } |
| |
| size_t HashCode = createHash(Hash); |
| StmtsByHash.push_back(std::make_pair(HashCode, StmtSequence(S, D))); |
| return HashCode; |
| } |
| |
| namespace { |
| /// Wrapper around FoldingSetNodeID that it can be used as the template |
| /// argument of the StmtDataCollector. |
| class FoldingSetNodeIDWrapper { |
| |
| llvm::FoldingSetNodeID &FS; |
| |
| public: |
| FoldingSetNodeIDWrapper(llvm::FoldingSetNodeID &FS) : FS(FS) {} |
| |
| void update(StringRef Str) { FS.AddString(Str); } |
| }; |
| } // end anonymous namespace |
| |
| /// Writes the relevant data from all statements and child statements |
| /// in the given StmtSequence into the given FoldingSetNodeID. |
| static void CollectStmtSequenceData(const StmtSequence &Sequence, |
| FoldingSetNodeIDWrapper &OutputData) { |
| for (const Stmt *S : Sequence) { |
| StmtDataCollector<FoldingSetNodeIDWrapper>(S, Sequence.getASTContext(), |
| OutputData); |
| |
| for (const Stmt *Child : S->children()) { |
| if (!Child) |
| continue; |
| |
| CollectStmtSequenceData(StmtSequence(Child, Sequence.getContainingDecl()), |
| OutputData); |
| } |
| } |
| } |
| |
| /// Returns true if both sequences are clones of each other. |
| static bool areSequencesClones(const StmtSequence &LHS, |
| const StmtSequence &RHS) { |
| // We collect the data from all statements in the sequence as we did before |
| // when generating a hash value for each sequence. But this time we don't |
| // hash the collected data and compare the whole data set instead. This |
| // prevents any false-positives due to hash code collisions. |
| llvm::FoldingSetNodeID DataLHS, DataRHS; |
| FoldingSetNodeIDWrapper LHSWrapper(DataLHS); |
| FoldingSetNodeIDWrapper RHSWrapper(DataRHS); |
| |
| CollectStmtSequenceData(LHS, LHSWrapper); |
| CollectStmtSequenceData(RHS, RHSWrapper); |
| |
| return DataLHS == DataRHS; |
| } |
| |
| void RecursiveCloneTypeIIConstraint::constrain( |
| std::vector<CloneDetector::CloneGroup> &Sequences) { |
| // FIXME: Maybe we can do this in-place and don't need this additional vector. |
| std::vector<CloneDetector::CloneGroup> Result; |
| |
| for (CloneDetector::CloneGroup &Group : Sequences) { |
| // We assume in the following code that the Group is non-empty, so we |
| // skip all empty groups. |
| if (Group.empty()) |
| continue; |
| |
| std::vector<std::pair<size_t, StmtSequence>> StmtsByHash; |
| |
| // Generate hash codes for all children of S and save them in StmtsByHash. |
| for (const StmtSequence &S : Group) { |
| saveHash(S.front(), S.getContainingDecl(), StmtsByHash); |
| } |
| |
| // Sort hash_codes in StmtsByHash. |
| std::stable_sort(StmtsByHash.begin(), StmtsByHash.end(), |
| [this](std::pair<size_t, StmtSequence> LHS, |
| std::pair<size_t, StmtSequence> RHS) { |
| return LHS.first < RHS.first; |
| }); |
| |
| // Check for each StmtSequence if its successor has the same hash value. |
| // We don't check the last StmtSequence as it has no successor. |
| // Note: The 'size - 1 ' in the condition is safe because we check for an |
| // empty Group vector at the beginning of this function. |
| for (unsigned i = 0; i < StmtsByHash.size() - 1; ++i) { |
| const auto Current = StmtsByHash[i]; |
| |
| // It's likely that we just found an sequence of StmtSequences that |
| // represent a CloneGroup, so we create a new group and start checking and |
| // adding the StmtSequences in this sequence. |
| CloneDetector::CloneGroup NewGroup; |
| |
| size_t PrototypeHash = Current.first; |
| |
| for (; i < StmtsByHash.size(); ++i) { |
| // A different hash value means we have reached the end of the sequence. |
| if (PrototypeHash != StmtsByHash[i].first || |
| !areSequencesClones(StmtsByHash[i].second, Current.second)) { |
| // The current sequence could be the start of a new CloneGroup. So we |
| // decrement i so that we visit it again in the outer loop. |
| // Note: i can never be 0 at this point because we are just comparing |
| // the hash of the Current StmtSequence with itself in the 'if' above. |
| assert(i != 0); |
| --i; |
| break; |
| } |
| // Same hash value means we should add the StmtSequence to the current |
| // group. |
| NewGroup.push_back(StmtsByHash[i].second); |
| } |
| |
| // We created a new clone group with matching hash codes and move it to |
| // the result vector. |
| Result.push_back(NewGroup); |
| } |
| } |
| // Sequences is the output parameter, so we copy our result into it. |
| Sequences = Result; |
| } |
| |
| size_t MinComplexityConstraint::calculateStmtComplexity( |
| const StmtSequence &Seq, const std::string &ParentMacroStack) { |
| if (Seq.empty()) |
| return 0; |
| |
| size_t Complexity = 1; |
| |
| ASTContext &Context = Seq.getASTContext(); |
| |
| // Look up what macros expanded into the current statement. |
| std::string StartMacroStack = getMacroStack(Seq.getStartLoc(), Context); |
| std::string EndMacroStack = getMacroStack(Seq.getEndLoc(), Context); |
| |
| // First, check if ParentMacroStack is not empty which means we are currently |
| // dealing with a parent statement which was expanded from a macro. |
| // If this parent statement was expanded from the same macros as this |
| // statement, we reduce the initial complexity of this statement to zero. |
| // This causes that a group of statements that were generated by a single |
| // macro expansion will only increase the total complexity by one. |
| // Note: This is not the final complexity of this statement as we still |
| // add the complexity of the child statements to the complexity value. |
| if (!ParentMacroStack.empty() && (StartMacroStack == ParentMacroStack && |
| EndMacroStack == ParentMacroStack)) { |
| Complexity = 0; |
| } |
| |
| // Iterate over the Stmts in the StmtSequence and add their complexity values |
| // to the current complexity value. |
| if (Seq.holdsSequence()) { |
| for (const Stmt *S : Seq) { |
| Complexity += calculateStmtComplexity( |
| StmtSequence(S, Seq.getContainingDecl()), StartMacroStack); |
| } |
| } else { |
| for (const Stmt *S : Seq.front()->children()) { |
| Complexity += calculateStmtComplexity( |
| StmtSequence(S, Seq.getContainingDecl()), StartMacroStack); |
| } |
| } |
| return Complexity; |
| } |
| |
| void MatchingVariablePatternConstraint::constrain( |
| std::vector<CloneDetector::CloneGroup> &CloneGroups) { |
| CloneConstraint::splitCloneGroups( |
| CloneGroups, [](const StmtSequence &A, const StmtSequence &B) { |
| VariablePattern PatternA(A); |
| VariablePattern PatternB(B); |
| return PatternA.countPatternDifferences(PatternB) == 0; |
| }); |
| } |
| |
| void CloneConstraint::splitCloneGroups( |
| std::vector<CloneDetector::CloneGroup> &CloneGroups, |
| std::function<bool(const StmtSequence &, const StmtSequence &)> Compare) { |
| std::vector<CloneDetector::CloneGroup> Result; |
| for (auto &HashGroup : CloneGroups) { |
| // Contains all indexes in HashGroup that were already added to a |
| // CloneGroup. |
| std::vector<char> Indexes; |
| Indexes.resize(HashGroup.size()); |
| |
| for (unsigned i = 0; i < HashGroup.size(); ++i) { |
| // Skip indexes that are already part of a CloneGroup. |
| if (Indexes[i]) |
| continue; |
| |
| // Pick the first unhandled StmtSequence and consider it as the |
| // beginning |
| // of a new CloneGroup for now. |
| // We don't add i to Indexes because we never iterate back. |
| StmtSequence Prototype = HashGroup[i]; |
| CloneDetector::CloneGroup PotentialGroup = {Prototype}; |
| ++Indexes[i]; |
| |
| // Check all following StmtSequences for clones. |
| for (unsigned j = i + 1; j < HashGroup.size(); ++j) { |
| // Skip indexes that are already part of a CloneGroup. |
| if (Indexes[j]) |
| continue; |
| |
| // If a following StmtSequence belongs to our CloneGroup, we add it to |
| // it. |
| const StmtSequence &Candidate = HashGroup[j]; |
| |
| if (!Compare(Prototype, Candidate)) |
| continue; |
| |
| PotentialGroup.push_back(Candidate); |
| // Make sure we never visit this StmtSequence again. |
| ++Indexes[j]; |
| } |
| |
| // Otherwise, add it to the result and continue searching for more |
| // groups. |
| Result.push_back(PotentialGroup); |
| } |
| |
| assert(std::all_of(Indexes.begin(), Indexes.end(), |
| [](char c) { return c == 1; })); |
| } |
| CloneGroups = Result; |
| } |
| |
| void VariablePattern::addVariableOccurence(const VarDecl *VarDecl, |
| const Stmt *Mention) { |
| // First check if we already reference this variable |
| for (size_t KindIndex = 0; KindIndex < Variables.size(); ++KindIndex) { |
| if (Variables[KindIndex] == VarDecl) { |
| // If yes, add a new occurence that points to the existing entry in |
| // the Variables vector. |
| Occurences.emplace_back(KindIndex, Mention); |
| return; |
| } |
| } |
| // If this variable wasn't already referenced, add it to the list of |
| // referenced variables and add a occurence that points to this new entry. |
| Occurences.emplace_back(Variables.size(), Mention); |
| Variables.push_back(VarDecl); |
| } |
| |
| void VariablePattern::addVariables(const Stmt *S) { |
| // Sometimes we get a nullptr (such as from IfStmts which often have nullptr |
| // children). We skip such statements as they don't reference any |
| // variables. |
| if (!S) |
| return; |
| |
| // Check if S is a reference to a variable. If yes, add it to the pattern. |
| if (auto D = dyn_cast<DeclRefExpr>(S)) { |
| if (auto VD = dyn_cast<VarDecl>(D->getDecl()->getCanonicalDecl())) |
| addVariableOccurence(VD, D); |
| } |
| |
| // Recursively check all children of the given statement. |
| for (const Stmt *Child : S->children()) { |
| addVariables(Child); |
| } |
| } |
| |
| unsigned VariablePattern::countPatternDifferences( |
| const VariablePattern &Other, |
| VariablePattern::SuspiciousClonePair *FirstMismatch) { |
| unsigned NumberOfDifferences = 0; |
| |
| assert(Other.Occurences.size() == Occurences.size()); |
| for (unsigned i = 0; i < Occurences.size(); ++i) { |
| auto ThisOccurence = Occurences[i]; |
| auto OtherOccurence = Other.Occurences[i]; |
| if (ThisOccurence.KindID == OtherOccurence.KindID) |
| continue; |
| |
| ++NumberOfDifferences; |
| |
| // If FirstMismatch is not a nullptr, we need to store information about |
| // the first difference between the two patterns. |
| if (FirstMismatch == nullptr) |
| continue; |
| |
| // Only proceed if we just found the first difference as we only store |
| // information about the first difference. |
| if (NumberOfDifferences != 1) |
| continue; |
| |
| const VarDecl *FirstSuggestion = nullptr; |
| // If there is a variable available in the list of referenced variables |
| // which wouldn't break the pattern if it is used in place of the |
| // current variable, we provide this variable as the suggested fix. |
| if (OtherOccurence.KindID < Variables.size()) |
| FirstSuggestion = Variables[OtherOccurence.KindID]; |
| |
| // Store information about the first clone. |
| FirstMismatch->FirstCloneInfo = |
| VariablePattern::SuspiciousClonePair::SuspiciousCloneInfo( |
| Variables[ThisOccurence.KindID], ThisOccurence.Mention, |
| FirstSuggestion); |
| |
| // Same as above but with the other clone. We do this for both clones as |
| // we don't know which clone is the one containing the unintended |
| // pattern error. |
| const VarDecl *SecondSuggestion = nullptr; |
| if (ThisOccurence.KindID < Other.Variables.size()) |
| SecondSuggestion = Other.Variables[ThisOccurence.KindID]; |
| |
| // Store information about the second clone. |
| FirstMismatch->SecondCloneInfo = |
| VariablePattern::SuspiciousClonePair::SuspiciousCloneInfo( |
| Other.Variables[OtherOccurence.KindID], OtherOccurence.Mention, |
| SecondSuggestion); |
| |
| // SuspiciousClonePair guarantees that the first clone always has a |
| // suggested variable associated with it. As we know that one of the two |
| // clones in the pair always has suggestion, we swap the two clones |
| // in case the first clone has no suggested variable which means that |
| // the second clone has a suggested variable and should be first. |
| if (!FirstMismatch->FirstCloneInfo.Suggestion) |
| std::swap(FirstMismatch->FirstCloneInfo, FirstMismatch->SecondCloneInfo); |
| |
| // This ensures that we always have at least one suggestion in a pair. |
| assert(FirstMismatch->FirstCloneInfo.Suggestion); |
| } |
| |
| return NumberOfDifferences; |
| } |