clang/lib/StaticAnalyzer/Checkers/RetainCountChecker/RetainCountSummaries.cpp

//== RetainCountSummaries.cpp - Checks for leaks and other issues -*- 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 summaries implementation for RetainCountChecker, which
//  implements a reference count checker for Core Foundation and Cocoa
//  on (Mac OS X).
//
//===----------------------------------------------------------------------===//

#include "RetainCountSummaries.h"
#include "RetainCountChecker.h"

#include "clang/Analysis/DomainSpecific/CocoaConventions.h"
#include "clang/AST/Attr.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/ParentMap.h"

using namespace objc_retain;
using namespace clang;
using namespace ento;
using namespace retaincountchecker;

ArgEffects RetainSummaryManager::getArgEffects() {
  ArgEffects AE = ScratchArgs;
  ScratchArgs = AF.getEmptyMap();
  return AE;
}

const RetainSummary *
RetainSummaryManager::getPersistentSummary(const RetainSummary &OldSumm) {
  // Unique "simple" summaries -- those without ArgEffects.
  if (OldSumm.isSimple()) {
    ::llvm::FoldingSetNodeID ID;
    OldSumm.Profile(ID);

    void *Pos;
    CachedSummaryNode *N = SimpleSummaries.FindNodeOrInsertPos(ID, Pos);

    if (!N) {
      N = (CachedSummaryNode *) BPAlloc.Allocate<CachedSummaryNode>();
      new (N) CachedSummaryNode(OldSumm);
      SimpleSummaries.InsertNode(N, Pos);
    }

    return &N->getValue();
  }

  RetainSummary *Summ = (RetainSummary *) BPAlloc.Allocate<RetainSummary>();
  new (Summ) RetainSummary(OldSumm);
  return Summ;
}

static bool hasRCAnnotation(const Decl *D, StringRef rcAnnotation) {
  for (const auto *Ann : D->specific_attrs<AnnotateAttr>()) {
    if (Ann->getAnnotation() == rcAnnotation)
      return true;
  }
  return false;
}

static bool isRetain(const FunctionDecl *FD, StringRef FName) {
  return FName.startswith_lower("retain") || FName.endswith_lower("retain");
}

static bool isRelease(const FunctionDecl *FD, StringRef FName) {
  return FName.startswith_lower("release") || FName.endswith_lower("release");
}

static bool isAutorelease(const FunctionDecl *FD, StringRef FName) {
  return FName.startswith_lower("autorelease") ||
         FName.endswith_lower("autorelease");
}

const RetainSummary *
RetainSummaryManager::generateSummary(const FunctionDecl *FD,
                                      bool &AllowAnnotations) {
  // We generate "stop" summaries for implicitly defined functions.
  if (FD->isImplicit()) {
    return getPersistentStopSummary();
  }

  // [PR 3337] Use 'getAs<FunctionType>' to strip away any typedefs on the
  // function's type.
  const FunctionType *FT = FD->getType()->getAs<FunctionType>();
  const IdentifierInfo *II = FD->getIdentifier();
  if (!II)
    return getDefaultSummary();

  StringRef FName = II->getName();

  // Strip away preceding '_'.  Doing this here will effect all the checks
  // down below.
  FName = FName.substr(FName.find_first_not_of('_'));

  // Inspect the result type.
  QualType RetTy = FT->getReturnType();
  std::string RetTyName = RetTy.getAsString();

  // FIXME: This should all be refactored into a chain of "summary lookup"
  //  filters.
  assert(ScratchArgs.isEmpty());

  if (FName == "pthread_create" || FName == "pthread_setspecific") {
    // Part of: <rdar://problem/7299394> and <rdar://problem/11282706>.
    // This will be addressed better with IPA.
    return getPersistentStopSummary();
  } else if (FName == "CFPlugInInstanceCreate") {
    return getPersistentSummary(RetEffect::MakeNoRet());
  } else if (FName == "IORegistryEntrySearchCFProperty" ||
             (RetTyName == "CFMutableDictionaryRef" &&
              (FName == "IOBSDNameMatching" || FName == "IOServiceMatching" ||
               FName == "IOServiceNameMatching" ||
               FName == "IORegistryEntryIDMatching" ||
               FName == "IOOpenFirmwarePathMatching"))) {
    // Part of <rdar://problem/6961230>. (IOKit)
    // This should be addressed using a API table.
    return getPersistentSummary(RetEffect::MakeOwned(RetEffect::CF), DoNothing,
                             DoNothing);
  } else if (FName == "IOServiceGetMatchingService" ||
             FName == "IOServiceGetMatchingServices") {
    // FIXES: <rdar://problem/6326900>
    // This should be addressed using a API table.  This strcmp is also
    // a little gross, but there is no need to super optimize here.
    ScratchArgs = AF.add(ScratchArgs, 1, DecRef);
    return getPersistentSummary(RetEffect::MakeNoRet(), DoNothing, DoNothing);
  } else if (FName == "IOServiceAddNotification" ||
             FName == "IOServiceAddMatchingNotification") {
    // Part of <rdar://problem/6961230>. (IOKit)
    // This should be addressed using a API table.
    ScratchArgs = AF.add(ScratchArgs, 2, DecRef);
    return getPersistentSummary(RetEffect::MakeNoRet(), DoNothing, DoNothing);
  } else if (FName == "CVPixelBufferCreateWithBytes") {
    // FIXES: <rdar://problem/7283567>
    // Eventually this can be improved by recognizing that the pixel
    // buffer passed to CVPixelBufferCreateWithBytes is released via
    // a callback and doing full IPA to make sure this is done correctly.
    // FIXME: This function has an out parameter that returns an
    // allocated object.
    ScratchArgs = AF.add(ScratchArgs, 7, StopTracking);
    return getPersistentSummary(RetEffect::MakeNoRet(), DoNothing, DoNothing);
  } else if (FName == "CGBitmapContextCreateWithData") {
    // FIXES: <rdar://problem/7358899>
    // Eventually this can be improved by recognizing that 'releaseInfo'
    // passed to CGBitmapContextCreateWithData is released via
    // a callback and doing full IPA to make sure this is done correctly.
    ScratchArgs = AF.add(ScratchArgs, 8, StopTracking);
    return getPersistentSummary(RetEffect::MakeOwned(RetEffect::CF), DoNothing,
                             DoNothing);
  } else if (FName == "CVPixelBufferCreateWithPlanarBytes") {
    // FIXES: <rdar://problem/7283567>
    // Eventually this can be improved by recognizing that the pixel
    // buffer passed to CVPixelBufferCreateWithPlanarBytes is released
    // via a callback and doing full IPA to make sure this is done
    // correctly.
    ScratchArgs = AF.add(ScratchArgs, 12, StopTracking);
    return getPersistentSummary(RetEffect::MakeNoRet(), DoNothing, DoNothing);
  } else if (FName == "VTCompressionSessionEncodeFrame") {
    // The context argument passed to VTCompressionSessionEncodeFrame()
    // is passed to the callback specified when creating the session
    // (e.g. with VTCompressionSessionCreate()) which can release it.
    // To account for this possibility, conservatively stop tracking
    // the context.
    ScratchArgs = AF.add(ScratchArgs, 5, StopTracking);
    return getPersistentSummary(RetEffect::MakeNoRet(), DoNothing, DoNothing);
  } else if (FName == "dispatch_set_context" ||
             FName == "xpc_connection_set_context") {
    // <rdar://problem/11059275> - The analyzer currently doesn't have
    // a good way to reason about the finalizer function for libdispatch.
    // If we pass a context object that is memory managed, stop tracking it.
    // <rdar://problem/13783514> - Same problem, but for XPC.
    // FIXME: this hack should possibly go away once we can handle
    // libdispatch and XPC finalizers.
    ScratchArgs = AF.add(ScratchArgs, 1, StopTracking);
    return getPersistentSummary(RetEffect::MakeNoRet(), DoNothing, DoNothing);
  } else if (FName.startswith("NSLog")) {
    return getDoNothingSummary();
  } else if (FName.startswith("NS") &&
             (FName.find("Insert") != StringRef::npos)) {
    // Whitelist NSXXInsertXX, for example NSMapInsertIfAbsent, since they can
    // be deallocated by NSMapRemove. (radar://11152419)
    ScratchArgs = AF.add(ScratchArgs, 1, StopTracking);
    ScratchArgs = AF.add(ScratchArgs, 2, StopTracking);
    return getPersistentSummary(RetEffect::MakeNoRet(), DoNothing, DoNothing);
  }

  if (RetTy->isPointerType()) {
    // For CoreFoundation ('CF') types.
    if (cocoa::isRefType(RetTy, "CF", FName)) {
      if (isRetain(FD, FName)) {
        // CFRetain isn't supposed to be annotated. However, this may as well
        // be a user-made "safe" CFRetain function that is incorrectly
        // annotated as cf_returns_retained due to lack of better options.
        // We want to ignore such annotation.
        AllowAnnotations = false;

        return getUnarySummary(FT, cfretain);
      } else if (isAutorelease(FD, FName)) {
        // The headers use cf_consumed, but we can fully model CFAutorelease
        // ourselves.
        AllowAnnotations = false;

        return getUnarySummary(FT, cfautorelease);
      } else {
        return getCFCreateGetRuleSummary(FD);
      }
    }

    // For CoreGraphics ('CG') and CoreVideo ('CV') types.
    if (cocoa::isRefType(RetTy, "CG", FName) ||
        cocoa::isRefType(RetTy, "CV", FName)) {
      if (isRetain(FD, FName))
        return getUnarySummary(FT, cfretain);
      else
        return getCFCreateGetRuleSummary(FD);
    }

    // For all other CF-style types, use the Create/Get
    // rule for summaries but don't support Retain functions
    // with framework-specific prefixes.
    if (coreFoundation::isCFObjectRef(RetTy)) {
      return getCFCreateGetRuleSummary(FD);
    }

    if (FD->hasAttr<CFAuditedTransferAttr>()) {
      return getCFCreateGetRuleSummary(FD);
    }
  }

  // Check for release functions, the only kind of functions that we care
  // about that don't return a pointer type.
  if (FName.size() >= 2 && FName[0] == 'C' &&
      (FName[1] == 'F' || FName[1] == 'G')) {
    // Test for 'CGCF'.
    FName = FName.substr(FName.startswith("CGCF") ? 4 : 2);

    if (isRelease(FD, FName))
      return getUnarySummary(FT, cfrelease);
    else {
      assert(ScratchArgs.isEmpty());
      // Remaining CoreFoundation and CoreGraphics functions.
      // We use to assume that they all strictly followed the ownership idiom
      // and that ownership cannot be transferred.  While this is technically
      // correct, many methods allow a tracked object to escape.  For example:
      //
      //   CFMutableDictionaryRef x = CFDictionaryCreateMutable(...);
      //   CFDictionaryAddValue(y, key, x);
      //   CFRelease(x);
      //   ... it is okay to use 'x' since 'y' has a reference to it
      //
      // We handle this and similar cases with the follow heuristic.  If the
      // function name contains "InsertValue", "SetValue", "AddValue",
      // "AppendValue", or "SetAttribute", then we assume that arguments may
      // "escape."  This means that something else holds on to the object,
      // allowing it be used even after its local retain count drops to 0.
      ArgEffect E = (StrInStrNoCase(FName, "InsertValue") != StringRef::npos ||
                     StrInStrNoCase(FName, "AddValue") != StringRef::npos ||
                     StrInStrNoCase(FName, "SetValue") != StringRef::npos ||
                     StrInStrNoCase(FName, "AppendValue") != StringRef::npos ||
                     StrInStrNoCase(FName, "SetAttribute") != StringRef::npos)
                        ? MayEscape
                        : DoNothing;

      return getPersistentSummary(RetEffect::MakeNoRet(), DoNothing, E);
    }
  }

  return getDefaultSummary();
}

const RetainSummary *
RetainSummaryManager::getFunctionSummary(const FunctionDecl *FD) {
  // If we don't know what function we're calling, use our default summary.
  if (!FD)
    return getDefaultSummary();

  // Look up a summary in our cache of FunctionDecls -> Summaries.
  FuncSummariesTy::iterator I = FuncSummaries.find(FD);
  if (I != FuncSummaries.end())
    return I->second;

  // No summary?  Generate one.
  bool AllowAnnotations = true;
  const RetainSummary *S = generateSummary(FD, AllowAnnotations);

  // Annotations override defaults.
  if (AllowAnnotations)
    updateSummaryFromAnnotations(S, FD);

  FuncSummaries[FD] = S;
  return S;
}

//===----------------------------------------------------------------------===//
// Summary creation for functions (largely uses of Core Foundation).
//===----------------------------------------------------------------------===//


static ArgEffect getStopTrackingHardEquivalent(ArgEffect E) {
  switch (E) {
  case DoNothing:
  case Autorelease:
  case DecRefBridgedTransferred:
  case IncRef:
  case IncRefMsg:
  case UnretainedOutParameter:
  case RetainedOutParameter:
  case MayEscape:
  case StopTracking:
  case StopTrackingHard:
    return StopTrackingHard;
  case DecRef:
  case DecRefAndStopTrackingHard:
    return DecRefAndStopTrackingHard;
  case DecRefMsg:
  case DecRefMsgAndStopTrackingHard:
    return DecRefMsgAndStopTrackingHard;
  case Dealloc:
    return Dealloc;
  }

  llvm_unreachable("Unknown ArgEffect kind");
}

void RetainSummaryManager::updateSummaryForCall(const RetainSummary *&S,
                                                const CallEvent &Call) {
  if (Call.hasNonZeroCallbackArg()) {
    ArgEffect RecEffect =
      getStopTrackingHardEquivalent(S->getReceiverEffect());
    ArgEffect DefEffect =
      getStopTrackingHardEquivalent(S->getDefaultArgEffect());

    ArgEffects CustomArgEffects = S->getArgEffects();
    for (ArgEffects::iterator I = CustomArgEffects.begin(),
                              E = CustomArgEffects.end();
         I != E; ++I) {
      ArgEffect Translated = getStopTrackingHardEquivalent(I->second);
      if (Translated != DefEffect)
        ScratchArgs = AF.add(ScratchArgs, I->first, Translated);
    }

    RetEffect RE = RetEffect::MakeNoRetHard();

    // Special cases where the callback argument CANNOT free the return value.
    // This can generally only happen if we know that the callback will only be
    // called when the return value is already being deallocated.
    if (const SimpleFunctionCall *FC = dyn_cast<SimpleFunctionCall>(&Call)) {
      if (IdentifierInfo *Name = FC->getDecl()->getIdentifier()) {
        // When the CGBitmapContext is deallocated, the callback here will free
        // the associated data buffer.
        // The callback in dispatch_data_create frees the buffer, but not
        // the data object.
        if (Name->isStr("CGBitmapContextCreateWithData") ||
            Name->isStr("dispatch_data_create"))
          RE = S->getRetEffect();
      }
    }

    S = getPersistentSummary(RE, RecEffect, DefEffect);
  }

  // Special case '[super init];' and '[self init];'
  //
  // Even though calling '[super init]' without assigning the result to self
  // and checking if the parent returns 'nil' is a bad pattern, it is common.
  // Additionally, our Self Init checker already warns about it. To avoid
  // overwhelming the user with messages from both checkers, we model the case
  // of '[super init]' in cases when it is not consumed by another expression
  // as if the call preserves the value of 'self'; essentially, assuming it can
  // never fail and return 'nil'.
  // Note, we don't want to just stop tracking the value since we want the
  // RetainCount checker to report leaks and use-after-free if SelfInit checker
  // is turned off.
  if (const ObjCMethodCall *MC = dyn_cast<ObjCMethodCall>(&Call)) {
    if (MC->getMethodFamily() == OMF_init && MC->isReceiverSelfOrSuper()) {

      // Check if the message is not consumed, we know it will not be used in
      // an assignment, ex: "self = [super init]".
      const Expr *ME = MC->getOriginExpr();
      const LocationContext *LCtx = MC->getLocationContext();
      ParentMap &PM = LCtx->getAnalysisDeclContext()->getParentMap();
      if (!PM.isConsumedExpr(ME)) {
        RetainSummaryTemplate ModifiableSummaryTemplate(S, *this);
        ModifiableSummaryTemplate->setReceiverEffect(DoNothing);
        ModifiableSummaryTemplate->setRetEffect(RetEffect::MakeNoRet());
      }
    }
  }
}

const RetainSummary *
RetainSummaryManager::getSummary(const CallEvent &Call,
                                 ProgramStateRef State) {
  const RetainSummary *Summ;
  switch (Call.getKind()) {
  case CE_Function:
    Summ = getFunctionSummary(cast<SimpleFunctionCall>(Call).getDecl());
    break;
  case CE_CXXMember:
  case CE_CXXMemberOperator:
  case CE_Block:
  case CE_CXXConstructor:
  case CE_CXXDestructor:
  case CE_CXXAllocator:
    // FIXME: These calls are currently unsupported.
    return getPersistentStopSummary();
  case CE_ObjCMessage: {
    const ObjCMethodCall &Msg = cast<ObjCMethodCall>(Call);
    if (Msg.isInstanceMessage())
      Summ = getInstanceMethodSummary(Msg, State);
    else
      Summ = getClassMethodSummary(Msg);
    break;
  }
  }

  updateSummaryForCall(Summ, Call);

  assert(Summ && "Unknown call type?");
  return Summ;
}


const RetainSummary *
RetainSummaryManager::getCFCreateGetRuleSummary(const FunctionDecl *FD) {
  if (coreFoundation::followsCreateRule(FD))
    return getCFSummaryCreateRule(FD);

  return getCFSummaryGetRule(FD);
}

bool RetainSummaryManager::isTrustedReferenceCountImplementation(
    const FunctionDecl *FD) {
  return hasRCAnnotation(FD, "rc_ownership_trusted_implementation");
}

bool RetainSummaryManager::canEval(const CallExpr *CE,
                                   const FunctionDecl *FD,
                                   bool &hasTrustedImplementationAnnotation) {
  // For now, we're only handling the functions that return aliases of their
  // arguments: CFRetain (and its families).
  // Eventually we should add other functions we can model entirely,
  // such as CFRelease, which don't invalidate their arguments or globals.
  if (CE->getNumArgs() != 1)
    return false;

  IdentifierInfo *II = FD->getIdentifier();
  if (!II)
    return false;

  StringRef FName = II->getName();
  FName = FName.substr(FName.find_first_not_of('_'));

  QualType ResultTy = CE->getCallReturnType(Ctx);
  if (ResultTy->isPointerType()) {
    // Handle: (CF|CG|CV)Retain
    //         CFAutorelease
    // It's okay to be a little sloppy here.
    if (cocoa::isRefType(ResultTy, "CF", FName) ||
        cocoa::isRefType(ResultTy, "CG", FName) ||
        cocoa::isRefType(ResultTy, "CV", FName))
      return isRetain(FD, FName) || isAutorelease(FD, FName);

    if (FD->getDefinition()) {
      bool out = isTrustedReferenceCountImplementation(FD->getDefinition());
      hasTrustedImplementationAnnotation = out;
      return out;
    }
  }

  return false;

}

const RetainSummary *
RetainSummaryManager::getUnarySummary(const FunctionType* FT,
                                      UnaryFuncKind func) {

  // Sanity check that this is *really* a unary function.  This can
  // happen if people do weird things.
  const FunctionProtoType* FTP = dyn_cast<FunctionProtoType>(FT);
  if (!FTP || FTP->getNumParams() != 1)
    return getPersistentStopSummary();

  assert (ScratchArgs.isEmpty());

  ArgEffect Effect;
  switch (func) {
  case cfretain: Effect = IncRef; break;
  case cfrelease: Effect = DecRef; break;
  case cfautorelease: Effect = Autorelease; break;
  }

  ScratchArgs = AF.add(ScratchArgs, 0, Effect);
  return getPersistentSummary(RetEffect::MakeNoRet(), DoNothing, DoNothing);
}

const RetainSummary *
RetainSummaryManager::getCFSummaryCreateRule(const FunctionDecl *FD) {
  assert (ScratchArgs.isEmpty());

  return getPersistentSummary(RetEffect::MakeOwned(RetEffect::CF));
}

const RetainSummary *
RetainSummaryManager::getCFSummaryGetRule(const FunctionDecl *FD) {
  assert (ScratchArgs.isEmpty());
  return getPersistentSummary(RetEffect::MakeNotOwned(RetEffect::CF),
                              DoNothing, DoNothing);
}




//===----------------------------------------------------------------------===//
// Summary creation for Selectors.
//===----------------------------------------------------------------------===//

Optional<RetEffect>
RetainSummaryManager::getRetEffectFromAnnotations(QualType RetTy,
                                                  const Decl *D) {
  if (cocoa::isCocoaObjectRef(RetTy)) {
    if (D->hasAttr<NSReturnsRetainedAttr>())
      return ObjCAllocRetE;

    if (D->hasAttr<NSReturnsNotRetainedAttr>() ||
        D->hasAttr<NSReturnsAutoreleasedAttr>())
      return RetEffect::MakeNotOwned(RetEffect::ObjC);

  } else if (!RetTy->isPointerType()) {
    return None;
  }

  if (D->hasAttr<CFReturnsRetainedAttr>())
    return RetEffect::MakeOwned(RetEffect::CF);
  else if (hasRCAnnotation(D, "rc_ownership_returns_retained"))
    return RetEffect::MakeOwned(RetEffect::Generalized);

  if (D->hasAttr<CFReturnsNotRetainedAttr>())
    return RetEffect::MakeNotOwned(RetEffect::CF);

  return None;
}

void
RetainSummaryManager::updateSummaryFromAnnotations(const RetainSummary *&Summ,
                                                   const FunctionDecl *FD) {
  if (!FD)
    return;

  assert(Summ && "Must have a summary to add annotations to.");
  RetainSummaryTemplate Template(Summ, *this);

  // Effects on the parameters.
  unsigned parm_idx = 0;
  for (FunctionDecl::param_const_iterator pi = FD->param_begin(),
         pe = FD->param_end(); pi != pe; ++pi, ++parm_idx) {
    const ParmVarDecl *pd = *pi;
    if (pd->hasAttr<NSConsumedAttr>())
      Template->addArg(AF, parm_idx, DecRefMsg);
    else if (pd->hasAttr<CFConsumedAttr>() ||
             hasRCAnnotation(pd, "rc_ownership_consumed"))
      Template->addArg(AF, parm_idx, DecRef);
    else if (pd->hasAttr<CFReturnsRetainedAttr>() ||
             hasRCAnnotation(pd, "rc_ownership_returns_retained")) {
      QualType PointeeTy = pd->getType()->getPointeeType();
      if (!PointeeTy.isNull())
        if (coreFoundation::isCFObjectRef(PointeeTy))
          Template->addArg(AF, parm_idx, RetainedOutParameter);
    } else if (pd->hasAttr<CFReturnsNotRetainedAttr>()) {
      QualType PointeeTy = pd->getType()->getPointeeType();
      if (!PointeeTy.isNull())
        if (coreFoundation::isCFObjectRef(PointeeTy))
          Template->addArg(AF, parm_idx, UnretainedOutParameter);
    }
  }

  QualType RetTy = FD->getReturnType();
  if (Optional<RetEffect> RetE = getRetEffectFromAnnotations(RetTy, FD))
    Template->setRetEffect(*RetE);
}

void
RetainSummaryManager::updateSummaryFromAnnotations(const RetainSummary *&Summ,
                                                   const ObjCMethodDecl *MD) {
  if (!MD)
    return;

  assert(Summ && "Must have a valid summary to add annotations to");
  RetainSummaryTemplate Template(Summ, *this);

  // Effects on the receiver.
  if (MD->hasAttr<NSConsumesSelfAttr>())
    Template->setReceiverEffect(DecRefMsg);

  // Effects on the parameters.
  unsigned parm_idx = 0;
  for (ObjCMethodDecl::param_const_iterator
         pi=MD->param_begin(), pe=MD->param_end();
       pi != pe; ++pi, ++parm_idx) {
    const ParmVarDecl *pd = *pi;
    if (pd->hasAttr<NSConsumedAttr>())
      Template->addArg(AF, parm_idx, DecRefMsg);
    else if (pd->hasAttr<CFConsumedAttr>()) {
      Template->addArg(AF, parm_idx, DecRef);
    } else if (pd->hasAttr<CFReturnsRetainedAttr>()) {
      QualType PointeeTy = pd->getType()->getPointeeType();
      if (!PointeeTy.isNull())
        if (coreFoundation::isCFObjectRef(PointeeTy))
          Template->addArg(AF, parm_idx, RetainedOutParameter);
    } else if (pd->hasAttr<CFReturnsNotRetainedAttr>()) {
      QualType PointeeTy = pd->getType()->getPointeeType();
      if (!PointeeTy.isNull())
        if (coreFoundation::isCFObjectRef(PointeeTy))
          Template->addArg(AF, parm_idx, UnretainedOutParameter);
    }
  }

  QualType RetTy = MD->getReturnType();
  if (Optional<RetEffect> RetE = getRetEffectFromAnnotations(RetTy, MD))
    Template->setRetEffect(*RetE);
}

const RetainSummary *
RetainSummaryManager::getStandardMethodSummary(const ObjCMethodDecl *MD,
                                               Selector S, QualType RetTy) {
  // Any special effects?
  ArgEffect ReceiverEff = DoNothing;
  RetEffect ResultEff = RetEffect::MakeNoRet();

  // Check the method family, and apply any default annotations.
  switch (MD ? MD->getMethodFamily() : S.getMethodFamily()) {
    case OMF_None:
    case OMF_initialize:
    case OMF_performSelector:
      // Assume all Objective-C methods follow Cocoa Memory Management rules.
      // FIXME: Does the non-threaded performSelector family really belong here?
      // The selector could be, say, @selector(copy).
      if (cocoa::isCocoaObjectRef(RetTy))
        ResultEff = RetEffect::MakeNotOwned(RetEffect::ObjC);
      else if (coreFoundation::isCFObjectRef(RetTy)) {
        // ObjCMethodDecl currently doesn't consider CF objects as valid return
        // values for alloc, new, copy, or mutableCopy, so we have to
        // double-check with the selector. This is ugly, but there aren't that
        // many Objective-C methods that return CF objects, right?
        if (MD) {
          switch (S.getMethodFamily()) {
          case OMF_alloc:
          case OMF_new:
          case OMF_copy:
          case OMF_mutableCopy:
            ResultEff = RetEffect::MakeOwned(RetEffect::CF);
            break;
          default:
            ResultEff = RetEffect::MakeNotOwned(RetEffect::CF);
            break;
          }
        } else {
          ResultEff = RetEffect::MakeNotOwned(RetEffect::CF);
        }
      }
      break;
    case OMF_init:
      ResultEff = ObjCInitRetE;
      ReceiverEff = DecRefMsg;
      break;
    case OMF_alloc:
    case OMF_new:
    case OMF_copy:
    case OMF_mutableCopy:
      if (cocoa::isCocoaObjectRef(RetTy))
        ResultEff = ObjCAllocRetE;
      else if (coreFoundation::isCFObjectRef(RetTy))
        ResultEff = RetEffect::MakeOwned(RetEffect::CF);
      break;
    case OMF_autorelease:
      ReceiverEff = Autorelease;
      break;
    case OMF_retain:
      ReceiverEff = IncRefMsg;
      break;
    case OMF_release:
      ReceiverEff = DecRefMsg;
      break;
    case OMF_dealloc:
      ReceiverEff = Dealloc;
      break;
    case OMF_self:
      // -self is handled specially by the ExprEngine to propagate the receiver.
      break;
    case OMF_retainCount:
    case OMF_finalize:
      // These methods don't return objects.
      break;
  }

  // If one of the arguments in the selector has the keyword 'delegate' we
  // should stop tracking the reference count for the receiver.  This is
  // because the reference count is quite possibly handled by a delegate
  // method.
  if (S.isKeywordSelector()) {
    for (unsigned i = 0, e = S.getNumArgs(); i != e; ++i) {
      StringRef Slot = S.getNameForSlot(i);
      if (Slot.substr(Slot.size() - 8).equals_lower("delegate")) {
        if (ResultEff == ObjCInitRetE)
          ResultEff = RetEffect::MakeNoRetHard();
        else
          ReceiverEff = StopTrackingHard;
      }
    }
  }

  if (ScratchArgs.isEmpty() && ReceiverEff == DoNothing &&
      ResultEff.getKind() == RetEffect::NoRet)
    return getDefaultSummary();

  return getPersistentSummary(ResultEff, ReceiverEff, MayEscape);
}

const RetainSummary *
RetainSummaryManager::getInstanceMethodSummary(const ObjCMethodCall &Msg,
                                               ProgramStateRef State) {
  const ObjCInterfaceDecl *ReceiverClass = nullptr;

  // We do better tracking of the type of the object than the core ExprEngine.
  // See if we have its type in our private state.
  // FIXME: Eventually replace the use of state->get<RefBindings> with
  // a generic API for reasoning about the Objective-C types of symbolic
  // objects.
  SVal ReceiverV = Msg.getReceiverSVal();
  if (SymbolRef Sym = ReceiverV.getAsLocSymbol())
    if (const RefVal *T = getRefBinding(State, Sym))
      if (const ObjCObjectPointerType *PT =
            T->getType()->getAs<ObjCObjectPointerType>())
        ReceiverClass = PT->getInterfaceDecl();

  // If we don't know what kind of object this is, fall back to its static type.
  if (!ReceiverClass)
    ReceiverClass = Msg.getReceiverInterface();

  // FIXME: The receiver could be a reference to a class, meaning that
  //  we should use the class method.
  // id x = [NSObject class];
  // [x performSelector:... withObject:... afterDelay:...];
  Selector S = Msg.getSelector();
  const ObjCMethodDecl *Method = Msg.getDecl();
  if (!Method && ReceiverClass)
    Method = ReceiverClass->getInstanceMethod(S);

  return getMethodSummary(S, ReceiverClass, Method, Msg.getResultType(),
                          ObjCMethodSummaries);
}

const RetainSummary *
RetainSummaryManager::getMethodSummary(Selector S, const ObjCInterfaceDecl *ID,
                                       const ObjCMethodDecl *MD, QualType RetTy,
                                       ObjCMethodSummariesTy &CachedSummaries) {

  // Look up a summary in our summary cache.
  const RetainSummary *Summ = CachedSummaries.find(ID, S);

  if (!Summ) {
    Summ = getStandardMethodSummary(MD, S, RetTy);

    // Annotations override defaults.
    updateSummaryFromAnnotations(Summ, MD);

    // Memoize the summary.
    CachedSummaries[ObjCSummaryKey(ID, S)] = Summ;
  }

  return Summ;
}

void RetainSummaryManager::InitializeClassMethodSummaries() {
  assert(ScratchArgs.isEmpty());
  // Create the [NSAssertionHandler currentHander] summary.
  addClassMethSummary("NSAssertionHandler", "currentHandler",
                getPersistentSummary(RetEffect::MakeNotOwned(RetEffect::ObjC)));

  // Create the [NSAutoreleasePool addObject:] summary.
  ScratchArgs = AF.add(ScratchArgs, 0, Autorelease);
  addClassMethSummary("NSAutoreleasePool", "addObject",
                      getPersistentSummary(RetEffect::MakeNoRet(),
                                           DoNothing, Autorelease));
}

void RetainSummaryManager::InitializeMethodSummaries() {

  assert (ScratchArgs.isEmpty());

  // Create the "init" selector.  It just acts as a pass-through for the
  // receiver.
  const RetainSummary *InitSumm = getPersistentSummary(ObjCInitRetE, DecRefMsg);
  addNSObjectMethSummary(GetNullarySelector("init", Ctx), InitSumm);

  // awakeAfterUsingCoder: behaves basically like an 'init' method.  It
  // claims the receiver and returns a retained object.
  addNSObjectMethSummary(GetUnarySelector("awakeAfterUsingCoder", Ctx),
                         InitSumm);

  // The next methods are allocators.
  const RetainSummary *AllocSumm = getPersistentSummary(ObjCAllocRetE);
  const RetainSummary *CFAllocSumm =
    getPersistentSummary(RetEffect::MakeOwned(RetEffect::CF));

  // Create the "retain" selector.
  RetEffect NoRet = RetEffect::MakeNoRet();
  const RetainSummary *Summ = getPersistentSummary(NoRet, IncRefMsg);
  addNSObjectMethSummary(GetNullarySelector("retain", Ctx), Summ);

  // Create the "release" selector.
  Summ = getPersistentSummary(NoRet, DecRefMsg);
  addNSObjectMethSummary(GetNullarySelector("release", Ctx), Summ);

  // Create the -dealloc summary.
  Summ = getPersistentSummary(NoRet, Dealloc);
  addNSObjectMethSummary(GetNullarySelector("dealloc", Ctx), Summ);

  // Create the "autorelease" selector.
  Summ = getPersistentSummary(NoRet, Autorelease);
  addNSObjectMethSummary(GetNullarySelector("autorelease", Ctx), Summ);

  // For NSWindow, allocated objects are (initially) self-owned.
  // FIXME: For now we opt for false negatives with NSWindow, as these objects
  //  self-own themselves.  However, they only do this once they are displayed.
  //  Thus, we need to track an NSWindow's display status.
  //  This is tracked in <rdar://problem/6062711>.
  //  See also http://llvm.org/bugs/show_bug.cgi?id=3714.
  const RetainSummary *NoTrackYet = getPersistentSummary(RetEffect::MakeNoRet(),
                                                   StopTracking,
                                                   StopTracking);

  addClassMethSummary("NSWindow", "alloc", NoTrackYet);

  // For NSPanel (which subclasses NSWindow), allocated objects are not
  //  self-owned.
  // FIXME: For now we don't track NSPanels. object for the same reason
  //   as for NSWindow objects.
  addClassMethSummary("NSPanel", "alloc", NoTrackYet);

  // For NSNull, objects returned by +null are singletons that ignore
  // retain/release semantics.  Just don't track them.
  // <rdar://problem/12858915>
  addClassMethSummary("NSNull", "null", NoTrackYet);

  // Don't track allocated autorelease pools, as it is okay to prematurely
  // exit a method.
  addClassMethSummary("NSAutoreleasePool", "alloc", NoTrackYet);
  addClassMethSummary("NSAutoreleasePool", "allocWithZone", NoTrackYet, false);
  addClassMethSummary("NSAutoreleasePool", "new", NoTrackYet);

  // Create summaries QCRenderer/QCView -createSnapShotImageOfType:
  addInstMethSummary("QCRenderer", AllocSumm, "createSnapshotImageOfType");
  addInstMethSummary("QCView", AllocSumm, "createSnapshotImageOfType");

  // Create summaries for CIContext, 'createCGImage' and
  // 'createCGLayerWithSize'.  These objects are CF objects, and are not
  // automatically garbage collected.
  addInstMethSummary("CIContext", CFAllocSumm, "createCGImage", "fromRect");
  addInstMethSummary("CIContext", CFAllocSumm, "createCGImage", "fromRect",
                     "format", "colorSpace");
  addInstMethSummary("CIContext", CFAllocSumm, "createCGLayerWithSize", "info");
}