lib/GR/GRCoreEngine.cpp

   1 //==- GRCoreEngine.cpp - Path-Sensitive Dataflow Engine ------------*- C++ -*-//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 //  This file defines a generic engine for intraprocedural, path-sensitive,
  11 //  dataflow analysis via graph reachability engine.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "clang/GR/PathSensitive/AnalysisManager.h"
  16 #include "clang/GR/PathSensitive/GRCoreEngine.h"
  17 #include "clang/GR/PathSensitive/GRExprEngine.h"
  18 #include "clang/Index/TranslationUnit.h"
  19 #include "clang/AST/Expr.h"
  20 #include "llvm/Support/Casting.h"
  21 #include "llvm/ADT/DenseMap.h"
  22 #include <vector>
  23 #include <queue>
  24
  25 using llvm::cast;
  26 using llvm::isa;
  27 using namespace clang;
  28 using namespace GR;
  29
  30 // This should be removed in the future.
  31 namespace clang {
  32 namespace GR {
  33 GRTransferFuncs* MakeCFRefCountTF(ASTContext& Ctx, bool GCEnabled,
  34                                   const LangOptions& lopts);
  35 }
  36 }
  37
  38 //===----------------------------------------------------------------------===//
  39 // Worklist classes for exploration of reachable states.
  40 //===----------------------------------------------------------------------===//
  41
  42 GRWorkList::Visitor::~Visitor() {}
  43
  44 namespace {
  45 class DFS : public GRWorkList {
  46   llvm::SmallVector<GRWorkListUnit,20> Stack;
  47 public:
  48   virtual bool hasWork() const {
  49     return !Stack.empty();
  50   }
  51
  52   virtual void Enqueue(const GRWorkListUnit& U) {
  53     Stack.push_back(U);
  54   }
  55
  56   virtual GRWorkListUnit Dequeue() {
  57     assert (!Stack.empty());
  58     const GRWorkListUnit& U = Stack.back();
  59     Stack.pop_back(); // This technically "invalidates" U, but we are fine.
  60     return U;
  61   }
  62
  63   virtual bool VisitItemsInWorkList(Visitor &V) {
  64     for (llvm::SmallVectorImpl<GRWorkListUnit>::iterator
  65          I = Stack.begin(), E = Stack.end(); I != E; ++I) {
  66       if (V.Visit(*I))
  67         return true;
  68     }
  69     return false;
  70   }
  71 };
  72
  73 class BFS : public GRWorkList {
  74   std::deque<GRWorkListUnit> Queue;
  75 public:
  76   virtual bool hasWork() const {
  77     return !Queue.empty();
  78   }
  79
  80   virtual void Enqueue(const GRWorkListUnit& U) {
  81     Queue.push_front(U);
  82   }
  83
  84   virtual GRWorkListUnit Dequeue() {
  85     GRWorkListUnit U = Queue.front();
  86     Queue.pop_front();
  87     return U;
  88   }
  89
  90   virtual bool VisitItemsInWorkList(Visitor &V) {
  91     for (std::deque<GRWorkListUnit>::iterator
  92          I = Queue.begin(), E = Queue.end(); I != E; ++I) {
  93       if (V.Visit(*I))
  94         return true;
  95     }
  96     return false;
  97   }
  98 };
  99
 100 } // end anonymous namespace
 101
 102 // Place the dstor for GRWorkList here because it contains virtual member
 103 // functions, and we the code for the dstor generated in one compilation unit.
 104 GRWorkList::~GRWorkList() {}
 105
 106 GRWorkList *GRWorkList::MakeDFS() { return new DFS(); }
 107 GRWorkList *GRWorkList::MakeBFS() { return new BFS(); }
 108
 109 namespace {
 110   class BFSBlockDFSContents : public GRWorkList {
 111     std::deque<GRWorkListUnit> Queue;
 112     llvm::SmallVector<GRWorkListUnit,20> Stack;
 113   public:
 114     virtual bool hasWork() const {
 115       return !Queue.empty() || !Stack.empty();
 116     }
 117
 118     virtual void Enqueue(const GRWorkListUnit& U) {
 119       if (isa<BlockEntrance>(U.getNode()->getLocation()))
 120         Queue.push_front(U);
 121       else
 122         Stack.push_back(U);
 123     }
 124
 125     virtual GRWorkListUnit Dequeue() {
 126       // Process all basic blocks to completion.
 127       if (!Stack.empty()) {
 128         const GRWorkListUnit& U = Stack.back();
 129         Stack.pop_back(); // This technically "invalidates" U, but we are fine.
 130         return U;
 131       }
 132
 133       assert(!Queue.empty());
 134       // Don't use const reference.  The subsequent pop_back() might make it
 135       // unsafe.
 136       GRWorkListUnit U = Queue.front();
 137       Queue.pop_front();
 138       return U;
 139     }
 140     virtual bool VisitItemsInWorkList(Visitor &V) {
 141       for (llvm::SmallVectorImpl<GRWorkListUnit>::iterator
 142            I = Stack.begin(), E = Stack.end(); I != E; ++I) {
 143         if (V.Visit(*I))
 144           return true;
 145       }
 146       for (std::deque<GRWorkListUnit>::iterator
 147            I = Queue.begin(), E = Queue.end(); I != E; ++I) {
 148         if (V.Visit(*I))
 149           return true;
 150       }
 151       return false;
 152     }
 153
 154   };
 155 } // end anonymous namespace
 156
 157 GRWorkList* GRWorkList::MakeBFSBlockDFSContents() {
 158   return new BFSBlockDFSContents();
 159 }
 160
 161 //===----------------------------------------------------------------------===//
 162 // Core analysis engine.
 163 //===----------------------------------------------------------------------===//
 164
 165 /// ExecuteWorkList - Run the worklist algorithm for a maximum number of steps.
 166 bool GRCoreEngine::ExecuteWorkList(const LocationContext *L, unsigned Steps,
 167                                    const GRState *InitState) {
 168
 169   if (G->num_roots() == 0) { // Initialize the analysis by constructing
 170     // the root if none exists.
 171
 172     const CFGBlock* Entry = &(L->getCFG()->getEntry());
 173
 174     assert (Entry->empty() &&
 175             "Entry block must be empty.");
 176
 177     assert (Entry->succ_size() == 1 &&
 178             "Entry block must have 1 successor.");
 179
 180     // Get the solitary successor.
 181     const CFGBlock* Succ = *(Entry->succ_begin());
 182
 183     // Construct an edge representing the
 184     // starting location in the function.
 185     BlockEdge StartLoc(Entry, Succ, L);
 186
 187     // Set the current block counter to being empty.
 188     WList->setBlockCounter(BCounterFactory.GetEmptyCounter());
 189
 190     if (!InitState)
 191       // Generate the root.
 192       generateNode(StartLoc, getInitialState(L), 0);
 193     else
 194       generateNode(StartLoc, InitState, 0);
 195   }
 196
 197   // Check if we have a steps limit
 198   bool UnlimitedSteps = Steps == 0;
 199
 200   while (WList->hasWork()) {
 201     if (!UnlimitedSteps) {
 202       if (Steps == 0)
 203         break;
 204       --Steps;
 205     }
 206
 207     const GRWorkListUnit& WU = WList->Dequeue();
 208
 209     // Set the current block counter.
 210     WList->setBlockCounter(WU.getBlockCounter());
 211
 212     // Retrieve the node.
 213     ExplodedNode* Node = WU.getNode();
 214
 215     // Dispatch on the location type.
 216     switch (Node->getLocation().getKind()) {
 217       case ProgramPoint::BlockEdgeKind:
 218         HandleBlockEdge(cast<BlockEdge>(Node->getLocation()), Node);
 219         break;
 220
 221       case ProgramPoint::BlockEntranceKind:
 222         HandleBlockEntrance(cast<BlockEntrance>(Node->getLocation()), Node);
 223         break;
 224
 225       case ProgramPoint::BlockExitKind:
 226         assert (false && "BlockExit location never occur in forward analysis.");
 227         break;
 228
 229       case ProgramPoint::CallEnterKind:
 230         HandleCallEnter(cast<CallEnter>(Node->getLocation()), WU.getBlock(),
 231                         WU.getIndex(), Node);
 232         break;
 233
 234       case ProgramPoint::CallExitKind:
 235         HandleCallExit(cast<CallExit>(Node->getLocation()), Node);
 236         break;
 237
 238       default:
 239         assert(isa<PostStmt>(Node->getLocation()) ||
 240                isa<PostInitializer>(Node->getLocation()));
 241         HandlePostStmt(WU.getBlock(), WU.getIndex(), Node);
 242         break;
 243     }
 244   }
 245
 246   SubEngine.ProcessEndWorklist(hasWorkRemaining());
 247   return WList->hasWork();
 248 }
 249
 250 void GRCoreEngine::ExecuteWorkListWithInitialState(const LocationContext *L,
 251                                                    unsigned Steps,
 252                                                    const GRState *InitState,
 253                                                    ExplodedNodeSet &Dst) {
 254   ExecuteWorkList(L, Steps, InitState);
 255   for (llvm::SmallVectorImpl<ExplodedNode*>::iterator I = G->EndNodes.begin(),
 256                                            E = G->EndNodes.end(); I != E; ++I) {
 257     Dst.Add(*I);
 258   }
 259 }
 260
 261 void GRCoreEngine::HandleCallEnter(const CallEnter &L, const CFGBlock *Block,
 262                                    unsigned Index, ExplodedNode *Pred) {
 263   GRCallEnterNodeBuilder Builder(*this, Pred, L.getCallExpr(),
 264                                  L.getCalleeContext(), Block, Index);
 265   ProcessCallEnter(Builder);
 266 }
 267
 268 void GRCoreEngine::HandleCallExit(const CallExit &L, ExplodedNode *Pred) {
 269   GRCallExitNodeBuilder Builder(*this, Pred);
 270   ProcessCallExit(Builder);
 271 }
 272
 273 void GRCoreEngine::HandleBlockEdge(const BlockEdge& L, ExplodedNode* Pred) {
 274
 275   const CFGBlock* Blk = L.getDst();
 276
 277   // Check if we are entering the EXIT block.
 278   if (Blk == &(L.getLocationContext()->getCFG()->getExit())) {
 279
 280     assert (L.getLocationContext()->getCFG()->getExit().size() == 0
 281             && "EXIT block cannot contain Stmts.");
 282
 283     // Process the final state transition.
 284     GREndPathNodeBuilder Builder(Blk, Pred, this);
 285     ProcessEndPath(Builder);
 286
 287     // This path is done. Don't enqueue any more nodes.
 288     return;
 289   }
 290
 291   // FIXME: Should we allow ProcessBlockEntrance to also manipulate state?
 292
 293   if (ProcessBlockEntrance(Blk, Pred, WList->getBlockCounter()))
 294     generateNode(BlockEntrance(Blk, Pred->getLocationContext()),
 295                  Pred->State, Pred);
 296   else {
 297     blocksAborted.push_back(std::make_pair(L, Pred));
 298   }
 299 }
 300
 301 void GRCoreEngine::HandleBlockEntrance(const BlockEntrance& L,
 302                                        ExplodedNode* Pred) {
 303
 304   // Increment the block counter.
 305   GRBlockCounter Counter = WList->getBlockCounter();
 306   Counter = BCounterFactory.IncrementCount(Counter,
 307                              Pred->getLocationContext()->getCurrentStackFrame(),
 308                                            L.getBlock()->getBlockID());
 309   WList->setBlockCounter(Counter);
 310
 311   // Process the entrance of the block.
 312   if (CFGElement E = L.getFirstElement()) {
 313     GRStmtNodeBuilder Builder(L.getBlock(), 0, Pred, this,
 314                               SubEngine.getStateManager());
 315     ProcessElement(E, Builder);
 316   }
 317   else
 318     HandleBlockExit(L.getBlock(), Pred);
 319 }
 320
 321 void GRCoreEngine::HandleBlockExit(const CFGBlock * B, ExplodedNode* Pred) {
 322
 323   if (const Stmt* Term = B->getTerminator()) {
 324     switch (Term->getStmtClass()) {
 325       default:
 326         assert(false && "Analysis for this terminator not implemented.");
 327         break;
 328
 329       case Stmt::BinaryOperatorClass: // '&&' and '||'
 330         HandleBranch(cast<BinaryOperator>(Term)->getLHS(), Term, B, Pred);
 331         return;
 332
 333       case Stmt::ConditionalOperatorClass:
 334         HandleBranch(cast<ConditionalOperator>(Term)->getCond(), Term, B, Pred);
 335         return;
 336
 337         // FIXME: Use constant-folding in CFG construction to simplify this
 338         // case.
 339
 340       case Stmt::ChooseExprClass:
 341         HandleBranch(cast<ChooseExpr>(Term)->getCond(), Term, B, Pred);
 342         return;
 343
 344       case Stmt::DoStmtClass:
 345         HandleBranch(cast<DoStmt>(Term)->getCond(), Term, B, Pred);
 346         return;
 347
 348       case Stmt::ForStmtClass:
 349         HandleBranch(cast<ForStmt>(Term)->getCond(), Term, B, Pred);
 350         return;
 351
 352       case Stmt::ContinueStmtClass:
 353       case Stmt::BreakStmtClass:
 354       case Stmt::GotoStmtClass:
 355         break;
 356
 357       case Stmt::IfStmtClass:
 358         HandleBranch(cast<IfStmt>(Term)->getCond(), Term, B, Pred);
 359         return;
 360
 361       case Stmt::IndirectGotoStmtClass: {
 362         // Only 1 successor: the indirect goto dispatch block.
 363         assert (B->succ_size() == 1);
 364
 365         GRIndirectGotoNodeBuilder
 366            builder(Pred, B, cast<IndirectGotoStmt>(Term)->getTarget(),
 367                    *(B->succ_begin()), this);
 368
 369         ProcessIndirectGoto(builder);
 370         return;
 371       }
 372
 373       case Stmt::ObjCForCollectionStmtClass: {
 374         // In the case of ObjCForCollectionStmt, it appears twice in a CFG:
 375         //
 376         //  (1) inside a basic block, which represents the binding of the
 377         //      'element' variable to a value.
 378         //  (2) in a terminator, which represents the branch.
 379         //
 380         // For (1), subengines will bind a value (i.e., 0 or 1) indicating
 381         // whether or not collection contains any more elements.  We cannot
 382         // just test to see if the element is nil because a container can
 383         // contain nil elements.
 384         HandleBranch(Term, Term, B, Pred);
 385         return;
 386       }
 387
 388       case Stmt::SwitchStmtClass: {
 389         GRSwitchNodeBuilder builder(Pred, B, cast<SwitchStmt>(Term)->getCond(),
 390                                     this);
 391
 392         ProcessSwitch(builder);
 393         return;
 394       }
 395
 396       case Stmt::WhileStmtClass:
 397         HandleBranch(cast<WhileStmt>(Term)->getCond(), Term, B, Pred);
 398         return;
 399     }
 400   }
 401
 402   assert (B->succ_size() == 1 &&
 403           "Blocks with no terminator should have at most 1 successor.");
 404
 405   generateNode(BlockEdge(B, *(B->succ_begin()), Pred->getLocationContext()),
 406                Pred->State, Pred);
 407 }
 408
 409 void GRCoreEngine::HandleBranch(const Stmt* Cond, const Stmt* Term,
 410                                 const CFGBlock * B, ExplodedNode* Pred) {
 411   assert (B->succ_size() == 2);
 412
 413   GRBranchNodeBuilder Builder(B, *(B->succ_begin()), *(B->succ_begin()+1),
 414                               Pred, this);
 415
 416   ProcessBranch(Cond, Term, Builder);
 417 }
 418
 419 void GRCoreEngine::HandlePostStmt(const CFGBlock* B, unsigned StmtIdx,
 420                                   ExplodedNode* Pred) {
 421   assert (!B->empty());
 422
 423   if (StmtIdx == B->size())
 424     HandleBlockExit(B, Pred);
 425   else {
 426     GRStmtNodeBuilder Builder(B, StmtIdx, Pred, this,
 427                               SubEngine.getStateManager());
 428     ProcessElement((*B)[StmtIdx], Builder);
 429   }
 430 }
 431
 432 /// generateNode - Utility method to generate nodes, hook up successors,
 433 ///  and add nodes to the worklist.
 434 void GRCoreEngine::generateNode(const ProgramPoint& Loc,
 435                                 const GRState* State, ExplodedNode* Pred) {
 436
 437   bool IsNew;
 438   ExplodedNode* Node = G->getNode(Loc, State, &IsNew);
 439
 440   if (Pred)
 441     Node->addPredecessor(Pred, *G);  // Link 'Node' with its predecessor.
 442   else {
 443     assert (IsNew);
 444     G->addRoot(Node);  // 'Node' has no predecessor.  Make it a root.
 445   }
 446
 447   // Only add 'Node' to the worklist if it was freshly generated.
 448   if (IsNew) WList->Enqueue(Node);
 449 }
 450
 451 GRStmtNodeBuilder::GRStmtNodeBuilder(const CFGBlock* b, unsigned idx,
 452                                      ExplodedNode* N, GRCoreEngine* e,
 453                                      GRStateManager &mgr)
 454   : Eng(*e), B(*b), Idx(idx), Pred(N), Mgr(mgr),
 455     PurgingDeadSymbols(false), BuildSinks(false), HasGeneratedNode(false),
 456     PointKind(ProgramPoint::PostStmtKind), Tag(0) {
 457   Deferred.insert(N);
 458   CleanedState = Pred->getState();
 459 }
 460
 461 GRStmtNodeBuilder::~GRStmtNodeBuilder() {
 462   for (DeferredTy::iterator I=Deferred.begin(), E=Deferred.end(); I!=E; ++I)
 463     if (!(*I)->isSink())
 464       GenerateAutoTransition(*I);
 465 }
 466
 467 void GRStmtNodeBuilder::GenerateAutoTransition(ExplodedNode* N) {
 468   assert (!N->isSink());
 469
 470   // Check if this node entered a callee.
 471   if (isa<CallEnter>(N->getLocation())) {
 472     // Still use the index of the CallExpr. It's needed to create the callee
 473     // StackFrameContext.
 474     Eng.WList->Enqueue(N, &B, Idx);
 475     return;
 476   }
 477
 478   // Do not create extra nodes. Move to the next CFG element.
 479   if (isa<PostInitializer>(N->getLocation())) {
 480     Eng.WList->Enqueue(N, &B, Idx+1);
 481     return;
 482   }
 483
 484   PostStmt Loc(getStmt(), N->getLocationContext());
 485
 486   if (Loc == N->getLocation()) {
 487     // Note: 'N' should be a fresh node because otherwise it shouldn't be
 488     // a member of Deferred.
 489     Eng.WList->Enqueue(N, &B, Idx+1);
 490     return;
 491   }
 492
 493   bool IsNew;
 494   ExplodedNode* Succ = Eng.G->getNode(Loc, N->State, &IsNew);
 495   Succ->addPredecessor(N, *Eng.G);
 496
 497   if (IsNew)
 498     Eng.WList->Enqueue(Succ, &B, Idx+1);
 499 }
 500
 501 ExplodedNode* GRStmtNodeBuilder::MakeNode(ExplodedNodeSet& Dst, const Stmt* S,
 502                                           ExplodedNode* Pred, const GRState* St,
 503                                           ProgramPoint::Kind K) {
 504
 505   ExplodedNode* N = generateNode(S, St, Pred, K);
 506
 507   if (N) {
 508     if (BuildSinks)
 509       N->markAsSink();
 510     else
 511       Dst.Add(N);
 512   }
 513
 514   return N;
 515 }
 516
 517 static ProgramPoint GetProgramPoint(const Stmt *S, ProgramPoint::Kind K,
 518                                     const LocationContext *LC, const void *tag){
 519   switch (K) {
 520     default:
 521       assert(false && "Unhandled ProgramPoint kind");
 522     case ProgramPoint::PreStmtKind:
 523       return PreStmt(S, LC, tag);
 524     case ProgramPoint::PostStmtKind:
 525       return PostStmt(S, LC, tag);
 526     case ProgramPoint::PreLoadKind:
 527       return PreLoad(S, LC, tag);
 528     case ProgramPoint::PostLoadKind:
 529       return PostLoad(S, LC, tag);
 530     case ProgramPoint::PreStoreKind:
 531       return PreStore(S, LC, tag);
 532     case ProgramPoint::PostStoreKind:
 533       return PostStore(S, LC, tag);
 534     case ProgramPoint::PostLValueKind:
 535       return PostLValue(S, LC, tag);
 536     case ProgramPoint::PostPurgeDeadSymbolsKind:
 537       return PostPurgeDeadSymbols(S, LC, tag);
 538   }
 539 }
 540
 541 ExplodedNode*
 542 GRStmtNodeBuilder::generateNodeInternal(const Stmt* S, const GRState* state,
 543                                         ExplodedNode* Pred,
 544                                         ProgramPoint::Kind K,
 545                                         const void *tag) {
 546
 547   const ProgramPoint &L = GetProgramPoint(S, K, Pred->getLocationContext(),tag);
 548   return generateNodeInternal(L, state, Pred);
 549 }
 550
 551 ExplodedNode*
 552 GRStmtNodeBuilder::generateNodeInternal(const ProgramPoint &Loc,
 553                                         const GRState* State,
 554                                         ExplodedNode* Pred) {
 555   bool IsNew;
 556   ExplodedNode* N = Eng.G->getNode(Loc, State, &IsNew);
 557   N->addPredecessor(Pred, *Eng.G);
 558   Deferred.erase(Pred);
 559
 560   if (IsNew) {
 561     Deferred.insert(N);
 562     return N;
 563   }
 564
 565   return NULL;
 566 }
 567
 568 ExplodedNode* GRBranchNodeBuilder::generateNode(const GRState* State,
 569                                                 bool branch) {
 570
 571   // If the branch has been marked infeasible we should not generate a node.
 572   if (!isFeasible(branch))
 573     return NULL;
 574
 575   bool IsNew;
 576
 577   ExplodedNode* Succ =
 578     Eng.G->getNode(BlockEdge(Src,branch ? DstT:DstF,Pred->getLocationContext()),
 579                    State, &IsNew);
 580
 581   Succ->addPredecessor(Pred, *Eng.G);
 582
 583   if (branch)
 584     GeneratedTrue = true;
 585   else
 586     GeneratedFalse = true;
 587
 588   if (IsNew) {
 589     Deferred.push_back(Succ);
 590     return Succ;
 591   }
 592
 593   return NULL;
 594 }
 595
 596 GRBranchNodeBuilder::~GRBranchNodeBuilder() {
 597   if (!GeneratedTrue) generateNode(Pred->State, true);
 598   if (!GeneratedFalse) generateNode(Pred->State, false);
 599
 600   for (DeferredTy::iterator I=Deferred.begin(), E=Deferred.end(); I!=E; ++I)
 601     if (!(*I)->isSink()) Eng.WList->Enqueue(*I);
 602 }
 603
 604
 605 ExplodedNode*
 606 GRIndirectGotoNodeBuilder::generateNode(const iterator& I, const GRState* St,
 607                                         bool isSink) {
 608   bool IsNew;
 609
 610   ExplodedNode* Succ = Eng.G->getNode(BlockEdge(Src, I.getBlock(),
 611                                       Pred->getLocationContext()), St, &IsNew);
 612
 613   Succ->addPredecessor(Pred, *Eng.G);
 614
 615   if (IsNew) {
 616
 617     if (isSink)
 618       Succ->markAsSink();
 619     else
 620       Eng.WList->Enqueue(Succ);
 621
 622     return Succ;
 623   }
 624
 625   return NULL;
 626 }
 627
 628
 629 ExplodedNode*
 630 GRSwitchNodeBuilder::generateCaseStmtNode(const iterator& I, const GRState* St){
 631
 632   bool IsNew;
 633
 634   ExplodedNode* Succ = Eng.G->getNode(BlockEdge(Src, I.getBlock(),
 635                                        Pred->getLocationContext()), St, &IsNew);
 636   Succ->addPredecessor(Pred, *Eng.G);
 637
 638   if (IsNew) {
 639     Eng.WList->Enqueue(Succ);
 640     return Succ;
 641   }
 642
 643   return NULL;
 644 }
 645
 646
 647 ExplodedNode*
 648 GRSwitchNodeBuilder::generateDefaultCaseNode(const GRState* St, bool isSink) {
 649
 650   // Get the block for the default case.
 651   assert (Src->succ_rbegin() != Src->succ_rend());
 652   CFGBlock* DefaultBlock = *Src->succ_rbegin();
 653
 654   bool IsNew;
 655
 656   ExplodedNode* Succ = Eng.G->getNode(BlockEdge(Src, DefaultBlock,
 657                                        Pred->getLocationContext()), St, &IsNew);
 658   Succ->addPredecessor(Pred, *Eng.G);
 659
 660   if (IsNew) {
 661     if (isSink)
 662       Succ->markAsSink();
 663     else
 664       Eng.WList->Enqueue(Succ);
 665
 666     return Succ;
 667   }
 668
 669   return NULL;
 670 }
 671
 672 GREndPathNodeBuilder::~GREndPathNodeBuilder() {
 673   // Auto-generate an EOP node if one has not been generated.
 674   if (!HasGeneratedNode) {
 675     // If we are in an inlined call, generate CallExit node.
 676     if (Pred->getLocationContext()->getParent())
 677       GenerateCallExitNode(Pred->State);
 678     else
 679       generateNode(Pred->State);
 680   }
 681 }
 682
 683 ExplodedNode*
 684 GREndPathNodeBuilder::generateNode(const GRState* State, const void *tag,
 685                                    ExplodedNode* P) {
 686   HasGeneratedNode = true;
 687   bool IsNew;
 688
 689   ExplodedNode* Node = Eng.G->getNode(BlockEntrance(&B,
 690                                Pred->getLocationContext(), tag), State, &IsNew);
 691
 692   Node->addPredecessor(P ? P : Pred, *Eng.G);
 693
 694   if (IsNew) {
 695     Eng.G->addEndOfPath(Node);
 696     return Node;
 697   }
 698
 699   return NULL;
 700 }
 701
 702 void GREndPathNodeBuilder::GenerateCallExitNode(const GRState *state) {
 703   HasGeneratedNode = true;
 704   // Create a CallExit node and enqueue it.
 705   const StackFrameContext *LocCtx
 706                          = cast<StackFrameContext>(Pred->getLocationContext());
 707   const Stmt *CE = LocCtx->getCallSite();
 708
 709   // Use the the callee location context.
 710   CallExit Loc(CE, LocCtx);
 711
 712   bool isNew;
 713   ExplodedNode *Node = Eng.G->getNode(Loc, state, &isNew);
 714   Node->addPredecessor(Pred, *Eng.G);
 715
 716   if (isNew)
 717     Eng.WList->Enqueue(Node);
 718 }
 719
 720
 721 void GRCallEnterNodeBuilder::generateNode(const GRState *state) {
 722   // Check if the callee is in the same translation unit.
 723   if (CalleeCtx->getTranslationUnit() !=
 724       Pred->getLocationContext()->getTranslationUnit()) {
 725     // Create a new engine. We must be careful that the new engine should not
 726     // reference data structures owned by the old engine.
 727
 728     AnalysisManager &OldMgr = Eng.SubEngine.getAnalysisManager();
 729
 730     // Get the callee's translation unit.
 731     idx::TranslationUnit *TU = CalleeCtx->getTranslationUnit();
 732
 733     // Create a new AnalysisManager with components of the callee's
 734     // TranslationUnit.
 735     // The Diagnostic is actually shared when we create ASTUnits from AST files.
 736     AnalysisManager AMgr(TU->getASTContext(), TU->getDiagnostic(),
 737                          OldMgr.getLangOptions(),
 738                          OldMgr.getPathDiagnosticClient(),
 739                          OldMgr.getStoreManagerCreator(),
 740                          OldMgr.getConstraintManagerCreator(),
 741                          OldMgr.getIndexer(),
 742                          OldMgr.getMaxNodes(), OldMgr.getMaxVisit(),
 743                          OldMgr.shouldVisualizeGraphviz(),
 744                          OldMgr.shouldVisualizeUbigraph(),
 745                          OldMgr.shouldPurgeDead(),
 746                          OldMgr.shouldEagerlyAssume(),
 747                          OldMgr.shouldTrimGraph(),
 748                          OldMgr.shouldInlineCall(),
 749                      OldMgr.getAnalysisContextManager().getUseUnoptimizedCFG(),
 750                      OldMgr.getAnalysisContextManager().getAddImplicitDtors(),
 751                      OldMgr.getAnalysisContextManager().getAddInitializers());
 752     llvm::OwningPtr<GRTransferFuncs> TF(MakeCFRefCountTF(AMgr.getASTContext(),
 753                                                          /* GCEnabled */ false,
 754                                                         AMgr.getLangOptions()));
 755     // Create the new engine.
 756     GRExprEngine NewEng(AMgr, TF.take());
 757
 758     // Create the new LocationContext.
 759     AnalysisContext *NewAnaCtx = AMgr.getAnalysisContext(CalleeCtx->getDecl(),
 760                                                CalleeCtx->getTranslationUnit());
 761     const StackFrameContext *OldLocCtx = CalleeCtx;
 762     const StackFrameContext *NewLocCtx = AMgr.getStackFrame(NewAnaCtx,
 763                                                OldLocCtx->getParent(),
 764                                                OldLocCtx->getCallSite(),
 765                                                OldLocCtx->getCallSiteBlock(),
 766                                                OldLocCtx->getIndex());
 767
 768     // Now create an initial state for the new engine.
 769     const GRState *NewState = NewEng.getStateManager().MarshalState(state,
 770                                                                     NewLocCtx);
 771     ExplodedNodeSet ReturnNodes;
 772     NewEng.ExecuteWorkListWithInitialState(NewLocCtx, AMgr.getMaxNodes(),
 773                                            NewState, ReturnNodes);
 774     return;
 775   }
 776
 777   // Get the callee entry block.
 778   const CFGBlock *Entry = &(CalleeCtx->getCFG()->getEntry());
 779   assert(Entry->empty());
 780   assert(Entry->succ_size() == 1);
 781
 782   // Get the solitary successor.
 783   const CFGBlock *SuccB = *(Entry->succ_begin());
 784
 785   // Construct an edge representing the starting location in the callee.
 786   BlockEdge Loc(Entry, SuccB, CalleeCtx);
 787
 788   bool isNew;
 789   ExplodedNode *Node = Eng.G->getNode(Loc, state, &isNew);
 790   Node->addPredecessor(const_cast<ExplodedNode*>(Pred), *Eng.G);
 791
 792   if (isNew)
 793     Eng.WList->Enqueue(Node);
 794 }
 795
 796 void GRCallExitNodeBuilder::generateNode(const GRState *state) {
 797   // Get the callee's location context.
 798   const StackFrameContext *LocCtx
 799                          = cast<StackFrameContext>(Pred->getLocationContext());
 800   // When exiting an implicit automatic obj dtor call, the callsite is the Stmt
 801   // that triggers the dtor.
 802   PostStmt Loc(LocCtx->getCallSite(), LocCtx->getParent());
 803   bool isNew;
 804   ExplodedNode *Node = Eng.G->getNode(Loc, state, &isNew);
 805   Node->addPredecessor(const_cast<ExplodedNode*>(Pred), *Eng.G);
 806   if (isNew)
 807     Eng.WList->Enqueue(Node, LocCtx->getCallSiteBlock(),
 808                        LocCtx->getIndex() + 1);
 809 }