| //==- ObjCUnusedIVarsChecker.cpp - Check for unused ivars --------*- C++ -*-==// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines a CheckObjCUnusedIvars, a checker that |
| // analyzes an Objective-C class's interface/implementation to determine if it |
| // has any ivars that are never accessed. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "clang/Checker/Checkers/LocalCheckers.h" |
| #include "clang/Checker/BugReporter/PathDiagnostic.h" |
| #include "clang/Checker/BugReporter/BugReporter.h" |
| #include "clang/AST/ExprObjC.h" |
| #include "clang/AST/Expr.h" |
| #include "clang/AST/DeclObjC.h" |
| #include "clang/Basic/LangOptions.h" |
| #include "clang/Basic/SourceManager.h" |
| |
| using namespace clang; |
| |
| enum IVarState { Unused, Used }; |
| typedef llvm::DenseMap<const ObjCIvarDecl*,IVarState> IvarUsageMap; |
| |
| static void Scan(IvarUsageMap& M, const Stmt* S) { |
| if (!S) |
| return; |
| |
| if (const ObjCIvarRefExpr *Ex = dyn_cast<ObjCIvarRefExpr>(S)) { |
| const ObjCIvarDecl *D = Ex->getDecl(); |
| IvarUsageMap::iterator I = M.find(D); |
| if (I != M.end()) |
| I->second = Used; |
| return; |
| } |
| |
| // Blocks can reference an instance variable of a class. |
| if (const BlockExpr *BE = dyn_cast<BlockExpr>(S)) { |
| Scan(M, BE->getBody()); |
| return; |
| } |
| |
| for (Stmt::const_child_iterator I=S->child_begin(),E=S->child_end(); I!=E;++I) |
| Scan(M, *I); |
| } |
| |
| static void Scan(IvarUsageMap& M, const ObjCPropertyImplDecl* D) { |
| if (!D) |
| return; |
| |
| const ObjCIvarDecl* ID = D->getPropertyIvarDecl(); |
| |
| if (!ID) |
| return; |
| |
| IvarUsageMap::iterator I = M.find(ID); |
| if (I != M.end()) |
| I->second = Used; |
| } |
| |
| static void Scan(IvarUsageMap& M, const ObjCContainerDecl* D) { |
| // Scan the methods for accesses. |
| for (ObjCContainerDecl::instmeth_iterator I = D->instmeth_begin(), |
| E = D->instmeth_end(); I!=E; ++I) |
| Scan(M, (*I)->getBody()); |
| |
| if (const ObjCImplementationDecl *ID = dyn_cast<ObjCImplementationDecl>(D)) { |
| // Scan for @synthesized property methods that act as setters/getters |
| // to an ivar. |
| for (ObjCImplementationDecl::propimpl_iterator I = ID->propimpl_begin(), |
| E = ID->propimpl_end(); I!=E; ++I) |
| Scan(M, *I); |
| |
| // Scan the associated categories as well. |
| for (const ObjCCategoryDecl *CD = |
| ID->getClassInterface()->getCategoryList(); CD ; |
| CD = CD->getNextClassCategory()) { |
| if (const ObjCCategoryImplDecl *CID = CD->getImplementation()) |
| Scan(M, CID); |
| } |
| } |
| } |
| |
| static void Scan(IvarUsageMap &M, const DeclContext *C, const FileID FID, |
| SourceManager &SM) { |
| for (DeclContext::decl_iterator I=C->decls_begin(), E=C->decls_end(); |
| I!=E; ++I) |
| if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(*I)) { |
| SourceLocation L = FD->getLocStart(); |
| if (SM.getFileID(L) == FID) |
| Scan(M, FD->getBody()); |
| } |
| } |
| |
| void clang::CheckObjCUnusedIvar(const ObjCImplementationDecl *D, |
| BugReporter &BR) { |
| |
| const ObjCInterfaceDecl* ID = D->getClassInterface(); |
| IvarUsageMap M; |
| |
| // Iterate over the ivars. |
| for (ObjCInterfaceDecl::ivar_iterator I=ID->ivar_begin(), |
| E=ID->ivar_end(); I!=E; ++I) { |
| |
| const ObjCIvarDecl* ID = *I; |
| |
| // Ignore ivars that... |
| // (a) aren't private |
| // (b) explicitly marked unused |
| // (c) are iboutlets |
| if (ID->getAccessControl() != ObjCIvarDecl::Private || |
| ID->getAttr<UnusedAttr>() || ID->getAttr<IBOutletAttr>()) |
| continue; |
| |
| M[ID] = Unused; |
| } |
| |
| if (M.empty()) |
| return; |
| |
| // Now scan the implementation declaration. |
| Scan(M, D); |
| |
| // Any potentially unused ivars? |
| bool hasUnused = false; |
| for (IvarUsageMap::iterator I = M.begin(), E = M.end(); I!=E; ++I) |
| if (I->second == Unused) { |
| hasUnused = true; |
| break; |
| } |
| |
| if (!hasUnused) |
| return; |
| |
| // We found some potentially unused ivars. Scan the entire translation unit |
| // for functions inside the @implementation that reference these ivars. |
| // FIXME: In the future hopefully we can just use the lexical DeclContext |
| // to go from the ObjCImplementationDecl to the lexically "nested" |
| // C functions. |
| SourceManager &SM = BR.getSourceManager(); |
| Scan(M, D->getDeclContext(), SM.getFileID(D->getLocation()), SM); |
| |
| // Find ivars that are unused. |
| for (IvarUsageMap::iterator I = M.begin(), E = M.end(); I!=E; ++I) |
| if (I->second == Unused) { |
| std::string sbuf; |
| llvm::raw_string_ostream os(sbuf); |
| os << "Instance variable '" << I->first->getNameAsString() |
| << "' in class '" << ID->getNameAsString() |
| << "' is never used by the methods in its @implementation " |
| "(although it may be used by category methods)."; |
| |
| BR.EmitBasicReport("Unused instance variable", "Optimization", |
| os.str(), I->first->getLocation()); |
| } |
| } |