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diff --git a/lib/Checker/ObjCUnusedIVarsChecker.cpp b/lib/Checker/ObjCUnusedIVarsChecker.cpp
new file mode 100644
index 000000000000..04d897aec894
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+++ b/lib/Checker/ObjCUnusedIVarsChecker.cpp
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+//==- 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());
+    }
+}