C++ SymbolReaper::isLive方法代码示例

void IteratorChecker::checkDeadSymbols(SymbolReaper &SR,
                                       CheckerContext &C) const {
  // Cleanup
  auto State = C.getState();

  auto RegionMap = State->get<IteratorRegionMap>();
  for (const auto Reg : RegionMap) {
    if (!SR.isLiveRegion(Reg.first)) {
      State = State->remove<IteratorRegionMap>(Reg.first);
    }
  }

  auto SymbolMap = State->get<IteratorSymbolMap>();
  for (const auto Sym : SymbolMap) {
    if (!SR.isLive(Sym.first)) {
      State = State->remove<IteratorSymbolMap>(Sym.first);
    }
  }

  auto ContMap = State->get<ContainerMap>();
  for (const auto Cont : ContMap) {
    if (!SR.isLiveRegion(Cont.first)) {
      State = State->remove<ContainerMap>(Cont.first);
    }
  }

  auto ComparisonMap = State->get<IteratorComparisonMap>();
  for (const auto Comp : ComparisonMap) {
    if (!SR.isLive(Comp.first)) {
      State = State->remove<IteratorComparisonMap>(Comp.first);
    }
  }
}

Environment
EnvironmentManager::RemoveDeadBindings(Environment Env, const Stmt *S,
                                       SymbolReaper &SymReaper,
                                       const GRState *ST,
                              llvm::SmallVectorImpl<const MemRegion*> &DRoots) {

  CFG &C = *Env.getAnalysisContext().getCFG();

  // We construct a new Environment object entirely, as this is cheaper than
  // individually removing all the subexpression bindings (which will greatly
  // outnumber block-level expression bindings).
  Environment NewEnv = getInitialEnvironment(&Env.getAnalysisContext());

  // Iterate over the block-expr bindings.
  for (Environment::iterator I = Env.begin(), E = Env.end();
       I != E; ++I) {

    const Stmt *BlkExpr = I.getKey();

    // Not a block-level expression?
    if (!C.isBlkExpr(BlkExpr))
      continue;

    const SVal &X = I.getData();

    if (SymReaper.isLive(S, BlkExpr)) {
      // Copy the binding to the new map.
      NewEnv.ExprBindings = F.Add(NewEnv.ExprBindings, BlkExpr, X);

      // If the block expr's value is a memory region, then mark that region.
      if (isa<loc::MemRegionVal>(X)) {
        const MemRegion* R = cast<loc::MemRegionVal>(X).getRegion();
        DRoots.push_back(R);
        // Mark the super region of the RX as live.
        // e.g.: int x; char *y = (char*) &x; if (*y) ...
        // 'y' => element region. 'x' is its super region.
        // We only add one level super region for now.

        // FIXME: maybe multiple level of super regions should be added.
        if (const SubRegion *SR = dyn_cast<SubRegion>(R))
          DRoots.push_back(SR->getSuperRegion());
      }

      // Mark all symbols in the block expr's value live.
      MarkLiveCallback cb(SymReaper);
      ST->scanReachableSymbols(X, cb);
      continue;
    }

    // Otherwise the expression is dead with a couple exceptions.
    // Do not misclean LogicalExpr or ConditionalOperator.  It is dead at the
    // beginning of itself, but we need its UndefinedVal to determine its
    // SVal.
    if (X.isUndef() && cast<UndefinedVal>(X).getData())
      NewEnv.ExprBindings = F.Add(NewEnv.ExprBindings, BlkExpr, X);
  }

  return NewEnv;
}

static bool IsLiveRegion(SymbolReaper &Reaper, const MemRegion *MR) {
  MR = MR->getBaseRegion();

  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(MR))
    return Reaper.isLive(SR->getSymbol());

  if (const VarRegion *VR = dyn_cast<VarRegion>(MR))
    return Reaper.isLive(VR);

  // FIXME: This is a gross over-approximation. What we really need is a way to
  // tell if anything still refers to this region. Unlike SymbolicRegions,
  // AllocaRegions don't have associated symbols, though, so we don't actually
  // have a way to track their liveness.
  if (isa<AllocaRegion>(MR))
    return true;

  if (isa<CXXThisRegion>(MR))
    return true;

  if (isa<MemSpaceRegion>(MR))
    return true;

  return false;
}

// removeDeadBindings:
//  - Remove subexpression bindings.
//  - Remove dead block expression bindings.
//  - Keep live block expression bindings:
//   - Mark their reachable symbols live in SymbolReaper,
//     see ScanReachableSymbols.
//   - Mark the region in DRoots if the binding is a loc::MemRegionVal.
Environment
EnvironmentManager::removeDeadBindings(Environment Env,
                                       SymbolReaper &SymReaper,
                                       ProgramStateRef ST) {

  // We construct a new Environment object entirely, as this is cheaper than
  // individually removing all the subexpression bindings (which will greatly
  // outnumber block-level expression bindings).
  Environment NewEnv = getInitialEnvironment();

  MarkLiveCallback CB(SymReaper);
  ScanReachableSymbols RSScaner(ST, CB);

  llvm::ImmutableMapRef<EnvironmentEntry,SVal>
    EBMapRef(NewEnv.ExprBindings.getRootWithoutRetain(),
             F.getTreeFactory());

  // Iterate over the block-expr bindings.
  for (Environment::iterator I = Env.begin(), E = Env.end();
       I != E; ++I) {

    const EnvironmentEntry &BlkExpr = I.getKey();
    const SVal &X = I.getData();

    if (SymReaper.isLive(BlkExpr.getStmt(), BlkExpr.getLocationContext())) {
      // Copy the binding to the new map.
      EBMapRef = EBMapRef.add(BlkExpr, X);

      // If the block expr's value is a memory region, then mark that region.
      if (Optional<loc::MemRegionVal> R = X.getAs<loc::MemRegionVal>())
        SymReaper.markLive(R->getRegion());

      // Mark all symbols in the block expr's value live.
      RSScaner.scan(X);
      continue;
    } else {
      SymExpr::symbol_iterator SI = X.symbol_begin(), SE = X.symbol_end();
      for (; SI != SE; ++SI)
        SymReaper.maybeDead(*SI);
    }
  }

  NewEnv.ExprBindings = EBMapRef.asImmutableMap();
  return NewEnv;
}

void MacOSKeychainAPIChecker::checkDeadSymbols(SymbolReaper &SR,
                                               CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  AllocatedDataTy ASet = State->get<AllocatedData>();
  if (ASet.isEmpty())
    return;

  bool Changed = false;
  AllocationPairVec Errors;
  for (AllocatedDataTy::iterator I = ASet.begin(), E = ASet.end(); I != E; ++I) {
    if (SR.isLive(I->first))
      continue;

    Changed = true;
    State = State->remove<AllocatedData>(I->first);
    // If the allocated symbol is null or if the allocation call might have
    // returned an error, do not report.
    ConstraintManager &CMgr = State->getConstraintManager();
    ConditionTruthVal AllocFailed = CMgr.isNull(State, I.getKey());
    if (AllocFailed.isConstrainedTrue() ||
        definitelyReturnedError(I->second.Region, State, C.getSValBuilder()))
      continue;
    Errors.push_back(std::make_pair(I->first, &I->second));
  }
  if (!Changed) {
    // Generate the new, cleaned up state.
    C.addTransition(State);
    return;
  }

  static SimpleProgramPointTag Tag("MacOSKeychainAPIChecker : DeadSymbolsLeak");
  ExplodedNode *N = C.addTransition(C.getState(), C.getPredecessor(), &Tag);

  // Generate the error reports.
  for (AllocationPairVec::iterator I = Errors.begin(), E = Errors.end();
                                                       I != E; ++I) {
    C.emitReport(generateAllocatedDataNotReleasedReport(*I, N, C));
  }

  // Generate the new, cleaned up state.
  C.addTransition(State, N);
}

void MacOSKeychainAPIChecker::checkDeadSymbols(SymbolReaper &SR,
                                               CheckerContext &C) const {
  const ProgramState *State = C.getState();
  AllocatedSetTy ASet = State->get<AllocatedData>();
  if (ASet.isEmpty())
    return;

  bool Changed = false;
  AllocationPairVec Errors;
  for (AllocatedSetTy::iterator I = ASet.begin(), E = ASet.end(); I != E; ++I) {
    if (SR.isLive(I->first))
      continue;

    Changed = true;
    State = State->remove<AllocatedData>(I->first);
    // If the allocated symbol is null or if the allocation call might have
    // returned an error, do not report.
    if (State->getSymVal(I->first) ||
        definitelyReturnedError(I->second.Region, State, C.getSValBuilder()))
      continue;
    Errors.push_back(std::make_pair(I->first, &I->second));
  }
  if (!Changed)
    return;

  // Generate the new, cleaned up state.
  ExplodedNode *N = C.addTransition(State);
  if (!N)
    return;

  // Generate the error reports.
  for (AllocationPairVec::iterator I = Errors.begin(), E = Errors.end();
                                                       I != E; ++I) {
    C.EmitReport(generateAllocatedDataNotReleasedReport(*I, N));
  }
}

void InnerPointerChecker::checkDeadSymbols(SymbolReaper &SymReaper,
                                           CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  PtrSet::Factory &F = State->getStateManager().get_context<PtrSet>();
  RawPtrMapTy RPM = State->get<RawPtrMap>();
  for (const auto Entry : RPM) {
    if (!SymReaper.isLiveRegion(Entry.first)) {
      // Due to incomplete destructor support, some dead regions might
      // remain in the program state map. Clean them up.
      State = State->remove<RawPtrMap>(Entry.first);
    }
    if (const PtrSet *OldSet = State->get<RawPtrMap>(Entry.first)) {
      PtrSet CleanedUpSet = *OldSet;
      for (const auto Symbol : Entry.second) {
        if (!SymReaper.isLive(Symbol))
          CleanedUpSet = F.remove(CleanedUpSet, Symbol);
      }
      State = CleanedUpSet.isEmpty()
                  ? State->remove<RawPtrMap>(Entry.first)
                  : State->set<RawPtrMap>(Entry.first, CleanedUpSet);
    }
  }
  C.addTransition(State);
}

// removeDeadBindings:
//  - Remove subexpression bindings.
//  - Remove dead block expression bindings.
//  - Keep live block expression bindings:
//   - Mark their reachable symbols live in SymbolReaper,
//     see ScanReachableSymbols.
//   - Mark the region in DRoots if the binding is a loc::MemRegionVal.
Environment
EnvironmentManager::removeDeadBindings(Environment Env,
                                       SymbolReaper &SymReaper,
                                       const ProgramState *ST) {

  // We construct a new Environment object entirely, as this is cheaper than
  // individually removing all the subexpression bindings (which will greatly
  // outnumber block-level expression bindings).
  Environment NewEnv = getInitialEnvironment();
  
  SmallVector<std::pair<EnvironmentEntry, SVal>, 10> deferredLocations;

  MarkLiveCallback CB(SymReaper);
  ScanReachableSymbols RSScaner(ST, CB);

  llvm::ImmutableMapRef<EnvironmentEntry,SVal>
    EBMapRef(NewEnv.ExprBindings.getRootWithoutRetain(),
             F.getTreeFactory());

  // Iterate over the block-expr bindings.
  for (Environment::iterator I = Env.begin(), E = Env.end();
       I != E; ++I) {

    const EnvironmentEntry &BlkExpr = I.getKey();
    // For recorded locations (used when evaluating loads and stores), we
    // consider them live only when their associated normal expression is
    // also live.
    // NOTE: This assumes that loads/stores that evaluated to UnknownVal
    // still have an entry in the map.
    if (IsLocation(BlkExpr)) {
      deferredLocations.push_back(std::make_pair(BlkExpr, I.getData()));
      continue;
    }
    const SVal &X = I.getData();

    if (SymReaper.isLive(BlkExpr.getStmt(), BlkExpr.getLocationContext())) {
      // Copy the binding to the new map.
      EBMapRef = EBMapRef.add(BlkExpr, X);

      // If the block expr's value is a memory region, then mark that region.
      if (isa<loc::MemRegionVal>(X)) {
        const MemRegion *R = cast<loc::MemRegionVal>(X).getRegion();
        SymReaper.markLive(R);
      }

      // Mark all symbols in the block expr's value live.
      RSScaner.scan(X);
      continue;
    }

    // Otherwise the expression is dead with a couple exceptions.
    // Do not misclean LogicalExpr or ConditionalOperator.  It is dead at the
    // beginning of itself, but we need its UndefinedVal to determine its
    // SVal.
    if (X.isUndef() && cast<UndefinedVal>(X).getData())
      EBMapRef = EBMapRef.add(BlkExpr, X);
  }
  
  // Go through he deferred locations and add them to the new environment if
  // the correspond Stmt* is in the map as well.
  for (SmallVectorImpl<std::pair<EnvironmentEntry, SVal> >::iterator
      I = deferredLocations.begin(), E = deferredLocations.end(); I != E; ++I) {
    const EnvironmentEntry &En = I->first;
    const Stmt *S = (Stmt*) (((uintptr_t) En.getStmt()) & (uintptr_t) ~0x1);
    if (EBMapRef.lookup(EnvironmentEntry(S, En.getLocationContext())))
      EBMapRef = EBMapRef.add(En, I->second);
  }

  NewEnv.ExprBindings = EBMapRef.asImmutableMap();
  return NewEnv;
}

Store BasicStoreManager::RemoveDeadBindings(Store store, Stmt* Loc,
        SymbolReaper& SymReaper,
        llvm::SmallVectorImpl<const MemRegion*>& RegionRoots)
{
    BindingsTy B = GetBindings(store);
    typedef SVal::symbol_iterator symbol_iterator;

    // Iterate over the variable bindings.
    for (BindingsTy::iterator I=B.begin(), E=B.end(); I!=E ; ++I) {
        if (const VarRegion *VR = dyn_cast<VarRegion>(I.getKey())) {
            if (SymReaper.isLive(Loc, VR))
                RegionRoots.push_back(VR);
            else
                continue;
        }
        else if (isa<ObjCIvarRegion>(I.getKey())) {
            RegionRoots.push_back(I.getKey());
        }
        else
            continue;

        // Mark the bindings in the data as live.
        SVal X = I.getData();
        for (symbol_iterator SI=X.symbol_begin(), SE=X.symbol_end(); SI!=SE; ++SI)
            SymReaper.markLive(*SI);
    }

    // Scan for live variables and live symbols.
    llvm::SmallPtrSet<const MemRegion*, 10> Marked;

    while (!RegionRoots.empty()) {
        const MemRegion* MR = RegionRoots.back();
        RegionRoots.pop_back();

        while (MR) {
            if (const SymbolicRegion* SymR = dyn_cast<SymbolicRegion>(MR)) {
                SymReaper.markLive(SymR->getSymbol());
                break;
            }
            else if (isa<VarRegion>(MR) || isa<ObjCIvarRegion>(MR)) {
                if (Marked.count(MR))
                    break;

                Marked.insert(MR);
                SVal X = Retrieve(store, loc::MemRegionVal(MR));

                // FIXME: We need to handle symbols nested in region definitions.
                for (symbol_iterator SI=X.symbol_begin(),SE=X.symbol_end(); SI!=SE; ++SI)
                    SymReaper.markLive(*SI);

                if (!isa<loc::MemRegionVal>(X))
                    break;

                const loc::MemRegionVal& LVD = cast<loc::MemRegionVal>(X);
                RegionRoots.push_back(LVD.getRegion());
                break;
            }
            else if (const SubRegion* R = dyn_cast<SubRegion>(MR))
                MR = R->getSuperRegion();
            else
                break;
        }
    }

    // Remove dead variable bindings.
    for (BindingsTy::iterator I=B.begin(), E=B.end(); I!=E ; ++I) {
        const MemRegion* R = I.getKey();

        if (!Marked.count(R)) {
            store = Remove(store, ValMgr.makeLoc(R));
            SVal X = I.getData();

            for (symbol_iterator SI=X.symbol_begin(), SE=X.symbol_end(); SI!=SE; ++SI)
                SymReaper.maybeDead(*SI);
        }
    }

    return store;
}

Environment
EnvironmentManager::RemoveDeadBindings(Environment Env,
                                       SymbolReaper &SymReaper,
                                       const GRState *ST,
                              llvm::SmallVectorImpl<const MemRegion*> &DRoots) {

  CFG &C = *SymReaper.getLocationContext()->getCFG();

  // We construct a new Environment object entirely, as this is cheaper than
  // individually removing all the subexpression bindings (which will greatly
  // outnumber block-level expression bindings).
  Environment NewEnv = getInitialEnvironment();

  // Iterate over the block-expr bindings.
  for (Environment::iterator I = Env.begin(), E = Env.end();
       I != E; ++I) {

    const Stmt *BlkExpr = I.getKey();
    const SVal &X = I.getData();

    // Block-level expressions in callers are assumed always live.
    if (isBlockExprInCallers(BlkExpr, SymReaper.getLocationContext())) {
      NewEnv.ExprBindings = F.Add(NewEnv.ExprBindings, BlkExpr, X);

      if (isa<loc::MemRegionVal>(X)) {
        const MemRegion* R = cast<loc::MemRegionVal>(X).getRegion();
        DRoots.push_back(R);
      }

      // Mark all symbols in the block expr's value live.
      MarkLiveCallback cb(SymReaper);
      ST->scanReachableSymbols(X, cb);
      continue;
    }

    // Not a block-level expression?
    if (!C.isBlkExpr(BlkExpr))
      continue;

    if (SymReaper.isLive(BlkExpr)) {
      // Copy the binding to the new map.
      NewEnv.ExprBindings = F.Add(NewEnv.ExprBindings, BlkExpr, X);

      // If the block expr's value is a memory region, then mark that region.
      if (isa<loc::MemRegionVal>(X)) {
        const MemRegion* R = cast<loc::MemRegionVal>(X).getRegion();
        DRoots.push_back(R);
      }

      // Mark all symbols in the block expr's value live.
      MarkLiveCallback cb(SymReaper);
      ST->scanReachableSymbols(X, cb);
      continue;
    }

    // Otherwise the expression is dead with a couple exceptions.
    // Do not misclean LogicalExpr or ConditionalOperator.  It is dead at the
    // beginning of itself, but we need its UndefinedVal to determine its
    // SVal.
    if (X.isUndef() && cast<UndefinedVal>(X).getData())
      NewEnv.ExprBindings = F.Add(NewEnv.ExprBindings, BlkExpr, X);
  }

  return NewEnv;
}