CoreEngine.cpp revision 327952 
1//==- CoreEngine.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/StaticAnalyzer/Core/PathSensitive/CoreEngine.h"
16#include "clang/AST/Expr.h"
17#include "clang/AST/ExprCXX.h"
18#include "clang/AST/StmtCXX.h"
19#include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
20#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
21#include "llvm/ADT/Statistic.h"
22#include "llvm/Support/Casting.h"
23
24using namespace clang;
25using namespace ento;
26
27#define DEBUG_TYPE "CoreEngine"
28
29STATISTIC(NumSteps,
30            "The # of steps executed.");
31STATISTIC(NumReachedMaxSteps,
32            "The # of times we reached the max number of steps.");
33STATISTIC(NumPathsExplored,
34            "The # of paths explored by the analyzer.");
35
36//===----------------------------------------------------------------------===//
37// Worklist classes for exploration of reachable states.
38//===----------------------------------------------------------------------===//
39
40WorkList::Visitor::~Visitor() {}
41
42namespace {
43class DFS : public WorkList {
44  SmallVector<WorkListUnit,20> Stack;
45public:
46  bool hasWork() const override {
47    return !Stack.empty();
48  }
49
50  void enqueue(const WorkListUnit& U) override {
51    Stack.push_back(U);
52  }
53
54  WorkListUnit dequeue() override {
55    assert (!Stack.empty());
56    const WorkListUnit& U = Stack.back();
57    Stack.pop_back(); // This technically "invalidates" U, but we are fine.
58    return U;
59  }
60
61  bool visitItemsInWorkList(Visitor &V) override {
62    for (SmallVectorImpl<WorkListUnit>::iterator
63         I = Stack.begin(), E = Stack.end(); I != E; ++I) {
64      if (V.visit(*I))
65        return true;
66    }
67    return false;
68  }
69};
70
71class BFS : public WorkList {
72  std::deque<WorkListUnit> Queue;
73public:
74  bool hasWork() const override {
75    return !Queue.empty();
76  }
77
78  void enqueue(const WorkListUnit& U) override {
79    Queue.push_back(U);
80  }
81
82  WorkListUnit dequeue() override {
83    WorkListUnit U = Queue.front();
84    Queue.pop_front();
85    return U;
86  }
87
88  bool visitItemsInWorkList(Visitor &V) override {
89    for (std::deque<WorkListUnit>::iterator
90         I = Queue.begin(), E = Queue.end(); I != E; ++I) {
91      if (V.visit(*I))
92        return true;
93    }
94    return false;
95  }
96};
97
98} // end anonymous namespace
99
100// Place the dstor for WorkList here because it contains virtual member
101// functions, and we the code for the dstor generated in one compilation unit.
102WorkList::~WorkList() {}
103
104WorkList *WorkList::makeDFS() { return new DFS(); }
105WorkList *WorkList::makeBFS() { return new BFS(); }
106
107namespace {
108  class BFSBlockDFSContents : public WorkList {
109    std::deque<WorkListUnit> Queue;
110    SmallVector<WorkListUnit,20> Stack;
111  public:
112    bool hasWork() const override {
113      return !Queue.empty() || !Stack.empty();
114    }
115
116    void enqueue(const WorkListUnit& U) override {
117      if (U.getNode()->getLocation().getAs<BlockEntrance>())
118        Queue.push_front(U);
119      else
120        Stack.push_back(U);
121    }
122
123    WorkListUnit dequeue() override {
124      // Process all basic blocks to completion.
125      if (!Stack.empty()) {
126        const WorkListUnit& U = Stack.back();
127        Stack.pop_back(); // This technically "invalidates" U, but we are fine.
128        return U;
129      }
130
131      assert(!Queue.empty());
132      // Don't use const reference.  The subsequent pop_back() might make it
133      // unsafe.
134      WorkListUnit U = Queue.front();
135      Queue.pop_front();
136      return U;
137    }
138    bool visitItemsInWorkList(Visitor &V) override {
139      for (SmallVectorImpl<WorkListUnit>::iterator
140           I = Stack.begin(), E = Stack.end(); I != E; ++I) {
141        if (V.visit(*I))
142          return true;
143      }
144      for (std::deque<WorkListUnit>::iterator
145           I = Queue.begin(), E = Queue.end(); I != E; ++I) {
146        if (V.visit(*I))
147          return true;
148      }
149      return false;
150    }
151
152  };
153} // end anonymous namespace
154
155WorkList* WorkList::makeBFSBlockDFSContents() {
156  return new BFSBlockDFSContents();
157}
158
159//===----------------------------------------------------------------------===//
160// Core analysis engine.
161//===----------------------------------------------------------------------===//
162
163/// ExecuteWorkList - Run the worklist algorithm for a maximum number of steps.
164bool CoreEngine::ExecuteWorkList(const LocationContext *L, unsigned Steps,
165                                   ProgramStateRef InitState) {
166
167  if (G.num_roots() == 0) { // Initialize the analysis by constructing
168    // the root if none exists.
169
170    const CFGBlock *Entry = &(L->getCFG()->getEntry());
171
172    assert (Entry->empty() &&
173            "Entry block must be empty.");
174
175    assert (Entry->succ_size() == 1 &&
176            "Entry block must have 1 successor.");
177
178    // Mark the entry block as visited.
179    FunctionSummaries->markVisitedBasicBlock(Entry->getBlockID(),
180                                             L->getDecl(),
181                                             L->getCFG()->getNumBlockIDs());
182
183    // Get the solitary successor.
184    const CFGBlock *Succ = *(Entry->succ_begin());
185
186    // Construct an edge representing the
187    // starting location in the function.
188    BlockEdge StartLoc(Entry, Succ, L);
189
190    // Set the current block counter to being empty.
191    WList->setBlockCounter(BCounterFactory.GetEmptyCounter());
192
193    if (!InitState)
194      InitState = SubEng.getInitialState(L);
195
196    bool IsNew;
197    ExplodedNode *Node = G.getNode(StartLoc, InitState, false, &IsNew);
198    assert (IsNew);
199    G.addRoot(Node);
200
201    NodeBuilderContext BuilderCtx(*this, StartLoc.getDst(), Node);
202    ExplodedNodeSet DstBegin;
203    SubEng.processBeginOfFunction(BuilderCtx, Node, DstBegin, StartLoc);
204
205    enqueue(DstBegin);
206  }
207
208  // Check if we have a steps limit
209  bool UnlimitedSteps = Steps == 0;
210  // Cap our pre-reservation in the event that the user specifies
211  // a very large number of maximum steps.
212  const unsigned PreReservationCap = 4000000;
213  if(!UnlimitedSteps)
214    G.reserve(std::min(Steps,PreReservationCap));
215
216  while (WList->hasWork()) {
217    if (!UnlimitedSteps) {
218      if (Steps == 0) {
219        NumReachedMaxSteps++;
220        break;
221      }
222      --Steps;
223    }
224
225    NumSteps++;
226
227    const WorkListUnit& WU = WList->dequeue();
228
229    // Set the current block counter.
230    WList->setBlockCounter(WU.getBlockCounter());
231
232    // Retrieve the node.
233    ExplodedNode *Node = WU.getNode();
234
235    dispatchWorkItem(Node, Node->getLocation(), WU);
236  }
237  SubEng.processEndWorklist(hasWorkRemaining());
238  return WList->hasWork();
239}
240
241void CoreEngine::dispatchWorkItem(ExplodedNode* Pred, ProgramPoint Loc,
242                                  const WorkListUnit& WU) {
243  // Dispatch on the location type.
244  switch (Loc.getKind()) {
245    case ProgramPoint::BlockEdgeKind:
246      HandleBlockEdge(Loc.castAs<BlockEdge>(), Pred);
247      break;
248
249    case ProgramPoint::BlockEntranceKind:
250      HandleBlockEntrance(Loc.castAs<BlockEntrance>(), Pred);
251      break;
252
253    case ProgramPoint::BlockExitKind:
254      assert (false && "BlockExit location never occur in forward analysis.");
255      break;
256
257    case ProgramPoint::CallEnterKind: {
258      HandleCallEnter(Loc.castAs<CallEnter>(), Pred);
259      break;
260    }
261
262    case ProgramPoint::CallExitBeginKind:
263      SubEng.processCallExit(Pred);
264      break;
265
266    case ProgramPoint::EpsilonKind: {
267      assert(Pred->hasSinglePred() &&
268             "Assume epsilon has exactly one predecessor by construction");
269      ExplodedNode *PNode = Pred->getFirstPred();
270      dispatchWorkItem(Pred, PNode->getLocation(), WU);
271      break;
272    }
273    default:
274      assert(Loc.getAs<PostStmt>() ||
275             Loc.getAs<PostInitializer>() ||
276             Loc.getAs<PostImplicitCall>() ||
277             Loc.getAs<CallExitEnd>() ||
278             Loc.getAs<LoopExit>());
279      HandlePostStmt(WU.getBlock(), WU.getIndex(), Pred);
280      break;
281  }
282}
283
284bool CoreEngine::ExecuteWorkListWithInitialState(const LocationContext *L,
285                                                 unsigned Steps,
286                                                 ProgramStateRef InitState,
287                                                 ExplodedNodeSet &Dst) {
288  bool DidNotFinish = ExecuteWorkList(L, Steps, InitState);
289  for (ExplodedGraph::eop_iterator I = G.eop_begin(), E = G.eop_end(); I != E;
290       ++I) {
291    Dst.Add(*I);
292  }
293  return DidNotFinish;
294}
295
296void CoreEngine::HandleBlockEdge(const BlockEdge &L, ExplodedNode *Pred) {
297
298  const CFGBlock *Blk = L.getDst();
299  NodeBuilderContext BuilderCtx(*this, Blk, Pred);
300
301  // Mark this block as visited.
302  const LocationContext *LC = Pred->getLocationContext();
303  FunctionSummaries->markVisitedBasicBlock(Blk->getBlockID(),
304                                           LC->getDecl(),
305                                           LC->getCFG()->getNumBlockIDs());
306
307  // Check if we are entering the EXIT block.
308  if (Blk == &(L.getLocationContext()->getCFG()->getExit())) {
309
310    assert (L.getLocationContext()->getCFG()->getExit().size() == 0
311            && "EXIT block cannot contain Stmts.");
312
313    // Get return statement..
314    const ReturnStmt *RS = nullptr;
315    if (!L.getSrc()->empty()) {
316      if (Optional<CFGStmt> LastStmt = L.getSrc()->back().getAs<CFGStmt>()) {
317        if ((RS = dyn_cast<ReturnStmt>(LastStmt->getStmt()))) {
318          if (!RS->getRetValue())
319            RS = nullptr;
320        }
321      }
322    }
323
324    // Process the final state transition.
325    SubEng.processEndOfFunction(BuilderCtx, Pred, RS);
326
327    // This path is done. Don't enqueue any more nodes.
328    return;
329  }
330
331  // Call into the SubEngine to process entering the CFGBlock.
332  ExplodedNodeSet dstNodes;
333  BlockEntrance BE(Blk, Pred->getLocationContext());
334  NodeBuilderWithSinks nodeBuilder(Pred, dstNodes, BuilderCtx, BE);
335  SubEng.processCFGBlockEntrance(L, nodeBuilder, Pred);
336
337  // Auto-generate a node.
338  if (!nodeBuilder.hasGeneratedNodes()) {
339    nodeBuilder.generateNode(Pred->State, Pred);
340  }
341
342  // Enqueue nodes onto the worklist.
343  enqueue(dstNodes);
344}
345
346void CoreEngine::HandleBlockEntrance(const BlockEntrance &L,
347                                       ExplodedNode *Pred) {
348
349  // Increment the block counter.
350  const LocationContext *LC = Pred->getLocationContext();
351  unsigned BlockId = L.getBlock()->getBlockID();
352  BlockCounter Counter = WList->getBlockCounter();
353  Counter = BCounterFactory.IncrementCount(Counter, LC->getCurrentStackFrame(),
354                                           BlockId);
355  WList->setBlockCounter(Counter);
356
357  // Process the entrance of the block.
358  if (Optional<CFGElement> E = L.getFirstElement()) {
359    NodeBuilderContext Ctx(*this, L.getBlock(), Pred);
360    SubEng.processCFGElement(*E, Pred, 0, &Ctx);
361  }
362  else
363    HandleBlockExit(L.getBlock(), Pred);
364}
365
366void CoreEngine::HandleBlockExit(const CFGBlock * B, ExplodedNode *Pred) {
367
368  if (const Stmt *Term = B->getTerminator()) {
369    switch (Term->getStmtClass()) {
370      default:
371        llvm_unreachable("Analysis for this terminator not implemented.");
372
373      case Stmt::CXXBindTemporaryExprClass:
374        HandleCleanupTemporaryBranch(
375            cast<CXXBindTemporaryExpr>(B->getTerminator().getStmt()), B, Pred);
376        return;
377
378      // Model static initializers.
379      case Stmt::DeclStmtClass:
380        HandleStaticInit(cast<DeclStmt>(Term), B, Pred);
381        return;
382
383      case Stmt::BinaryOperatorClass: // '&&' and '||'
384        HandleBranch(cast<BinaryOperator>(Term)->getLHS(), Term, B, Pred);
385        return;
386
387      case Stmt::BinaryConditionalOperatorClass:
388      case Stmt::ConditionalOperatorClass:
389        HandleBranch(cast<AbstractConditionalOperator>(Term)->getCond(),
390                     Term, B, Pred);
391        return;
392
393        // FIXME: Use constant-folding in CFG construction to simplify this
394        // case.
395
396      case Stmt::ChooseExprClass:
397        HandleBranch(cast<ChooseExpr>(Term)->getCond(), Term, B, Pred);
398        return;
399
400      case Stmt::CXXTryStmtClass: {
401        // Generate a node for each of the successors.
402        // Our logic for EH analysis can certainly be improved.
403        for (CFGBlock::const_succ_iterator it = B->succ_begin(),
404             et = B->succ_end(); it != et; ++it) {
405          if (const CFGBlock *succ = *it) {
406            generateNode(BlockEdge(B, succ, Pred->getLocationContext()),
407                         Pred->State, Pred);
408          }
409        }
410        return;
411      }
412
413      case Stmt::DoStmtClass:
414        HandleBranch(cast<DoStmt>(Term)->getCond(), Term, B, Pred);
415        return;
416
417      case Stmt::CXXForRangeStmtClass:
418        HandleBranch(cast<CXXForRangeStmt>(Term)->getCond(), Term, B, Pred);
419        return;
420
421      case Stmt::ForStmtClass:
422        HandleBranch(cast<ForStmt>(Term)->getCond(), Term, B, Pred);
423        return;
424
425      case Stmt::ContinueStmtClass:
426      case Stmt::BreakStmtClass:
427      case Stmt::GotoStmtClass:
428        break;
429
430      case Stmt::IfStmtClass:
431        HandleBranch(cast<IfStmt>(Term)->getCond(), Term, B, Pred);
432        return;
433
434      case Stmt::IndirectGotoStmtClass: {
435        // Only 1 successor: the indirect goto dispatch block.
436        assert (B->succ_size() == 1);
437
438        IndirectGotoNodeBuilder
439           builder(Pred, B, cast<IndirectGotoStmt>(Term)->getTarget(),
440                   *(B->succ_begin()), this);
441
442        SubEng.processIndirectGoto(builder);
443        return;
444      }
445
446      case Stmt::ObjCForCollectionStmtClass: {
447        // In the case of ObjCForCollectionStmt, it appears twice in a CFG:
448        //
449        //  (1) inside a basic block, which represents the binding of the
450        //      'element' variable to a value.
451        //  (2) in a terminator, which represents the branch.
452        //
453        // For (1), subengines will bind a value (i.e., 0 or 1) indicating
454        // whether or not collection contains any more elements.  We cannot
455        // just test to see if the element is nil because a container can
456        // contain nil elements.
457        HandleBranch(Term, Term, B, Pred);
458        return;
459      }
460
461      case Stmt::SwitchStmtClass: {
462        SwitchNodeBuilder builder(Pred, B, cast<SwitchStmt>(Term)->getCond(),
463                                    this);
464
465        SubEng.processSwitch(builder);
466        return;
467      }
468
469      case Stmt::WhileStmtClass:
470        HandleBranch(cast<WhileStmt>(Term)->getCond(), Term, B, Pred);
471        return;
472    }
473  }
474
475  assert (B->succ_size() == 1 &&
476          "Blocks with no terminator should have at most 1 successor.");
477
478  generateNode(BlockEdge(B, *(B->succ_begin()), Pred->getLocationContext()),
479               Pred->State, Pred);
480}
481
482void CoreEngine::HandleCallEnter(const CallEnter &CE, ExplodedNode *Pred) {
483  NodeBuilderContext BuilderCtx(*this, CE.getEntry(), Pred);
484  SubEng.processCallEnter(BuilderCtx, CE, Pred);
485}
486
487void CoreEngine::HandleBranch(const Stmt *Cond, const Stmt *Term,
488                                const CFGBlock * B, ExplodedNode *Pred) {
489  assert(B->succ_size() == 2);
490  NodeBuilderContext Ctx(*this, B, Pred);
491  ExplodedNodeSet Dst;
492  SubEng.processBranch(Cond, Term, Ctx, Pred, Dst,
493                       *(B->succ_begin()), *(B->succ_begin()+1));
494  // Enqueue the new frontier onto the worklist.
495  enqueue(Dst);
496}
497
498void CoreEngine::HandleCleanupTemporaryBranch(const CXXBindTemporaryExpr *BTE,
499                                              const CFGBlock *B,
500                                              ExplodedNode *Pred) {
501  assert(B->succ_size() == 2);
502  NodeBuilderContext Ctx(*this, B, Pred);
503  ExplodedNodeSet Dst;
504  SubEng.processCleanupTemporaryBranch(BTE, Ctx, Pred, Dst, *(B->succ_begin()),
505                                       *(B->succ_begin() + 1));
506  // Enqueue the new frontier onto the worklist.
507  enqueue(Dst);
508}
509
510void CoreEngine::HandleStaticInit(const DeclStmt *DS, const CFGBlock *B,
511                                  ExplodedNode *Pred) {
512  assert(B->succ_size() == 2);
513  NodeBuilderContext Ctx(*this, B, Pred);
514  ExplodedNodeSet Dst;
515  SubEng.processStaticInitializer(DS, Ctx, Pred, Dst,
516                                  *(B->succ_begin()), *(B->succ_begin()+1));
517  // Enqueue the new frontier onto the worklist.
518  enqueue(Dst);
519}
520
521
522void CoreEngine::HandlePostStmt(const CFGBlock *B, unsigned StmtIdx,
523                                  ExplodedNode *Pred) {
524  assert(B);
525  assert(!B->empty());
526
527  if (StmtIdx == B->size())
528    HandleBlockExit(B, Pred);
529  else {
530    NodeBuilderContext Ctx(*this, B, Pred);
531    SubEng.processCFGElement((*B)[StmtIdx], Pred, StmtIdx, &Ctx);
532  }
533}
534
535/// generateNode - Utility method to generate nodes, hook up successors,
536///  and add nodes to the worklist.
537void CoreEngine::generateNode(const ProgramPoint &Loc,
538                              ProgramStateRef State,
539                              ExplodedNode *Pred) {
540
541  bool IsNew;
542  ExplodedNode *Node = G.getNode(Loc, State, false, &IsNew);
543
544  if (Pred)
545    Node->addPredecessor(Pred, G); // Link 'Node' with its predecessor.
546  else {
547    assert (IsNew);
548    G.addRoot(Node); // 'Node' has no predecessor.  Make it a root.
549  }
550
551  // Only add 'Node' to the worklist if it was freshly generated.
552  if (IsNew) WList->enqueue(Node);
553}
554
555void CoreEngine::enqueueStmtNode(ExplodedNode *N,
556                                 const CFGBlock *Block, unsigned Idx) {
557  assert(Block);
558  assert (!N->isSink());
559
560  // Check if this node entered a callee.
561  if (N->getLocation().getAs<CallEnter>()) {
562    // Still use the index of the CallExpr. It's needed to create the callee
563    // StackFrameContext.
564    WList->enqueue(N, Block, Idx);
565    return;
566  }
567
568  // Do not create extra nodes. Move to the next CFG element.
569  if (N->getLocation().getAs<PostInitializer>() ||
570      N->getLocation().getAs<PostImplicitCall>()||
571      N->getLocation().getAs<LoopExit>()) {
572    WList->enqueue(N, Block, Idx+1);
573    return;
574  }
575
576  if (N->getLocation().getAs<EpsilonPoint>()) {
577    WList->enqueue(N, Block, Idx);
578    return;
579  }
580
581  if ((*Block)[Idx].getKind() == CFGElement::NewAllocator) {
582    WList->enqueue(N, Block, Idx+1);
583    return;
584  }
585
586  // At this point, we know we're processing a normal statement.
587  CFGStmt CS = (*Block)[Idx].castAs<CFGStmt>();
588  PostStmt Loc(CS.getStmt(), N->getLocationContext());
589
590  if (Loc == N->getLocation().withTag(nullptr)) {
591    // Note: 'N' should be a fresh node because otherwise it shouldn't be
592    // a member of Deferred.
593    WList->enqueue(N, Block, Idx+1);
594    return;
595  }
596
597  bool IsNew;
598  ExplodedNode *Succ = G.getNode(Loc, N->getState(), false, &IsNew);
599  Succ->addPredecessor(N, G);
600
601  if (IsNew)
602    WList->enqueue(Succ, Block, Idx+1);
603}
604
605ExplodedNode *CoreEngine::generateCallExitBeginNode(ExplodedNode *N,
606                                                    const ReturnStmt *RS) {
607  // Create a CallExitBegin node and enqueue it.
608  const StackFrameContext *LocCtx
609                         = cast<StackFrameContext>(N->getLocationContext());
610
611  // Use the callee location context.
612  CallExitBegin Loc(LocCtx, RS);
613
614  bool isNew;
615  ExplodedNode *Node = G.getNode(Loc, N->getState(), false, &isNew);
616  Node->addPredecessor(N, G);
617  return isNew ? Node : nullptr;
618}
619
620
621void CoreEngine::enqueue(ExplodedNodeSet &Set) {
622  for (ExplodedNodeSet::iterator I = Set.begin(),
623                                 E = Set.end(); I != E; ++I) {
624    WList->enqueue(*I);
625  }
626}
627
628void CoreEngine::enqueue(ExplodedNodeSet &Set,
629                         const CFGBlock *Block, unsigned Idx) {
630  for (ExplodedNodeSet::iterator I = Set.begin(),
631                                 E = Set.end(); I != E; ++I) {
632    enqueueStmtNode(*I, Block, Idx);
633  }
634}
635
636void CoreEngine::enqueueEndOfFunction(ExplodedNodeSet &Set, const ReturnStmt *RS) {
637  for (ExplodedNodeSet::iterator I = Set.begin(), E = Set.end(); I != E; ++I) {
638    ExplodedNode *N = *I;
639    // If we are in an inlined call, generate CallExitBegin node.
640    if (N->getLocationContext()->getParent()) {
641      N = generateCallExitBeginNode(N, RS);
642      if (N)
643        WList->enqueue(N);
644    } else {
645      // TODO: We should run remove dead bindings here.
646      G.addEndOfPath(N);
647      NumPathsExplored++;
648    }
649  }
650}
651
652
653void NodeBuilder::anchor() { }
654
655ExplodedNode* NodeBuilder::generateNodeImpl(const ProgramPoint &Loc,
656                                            ProgramStateRef State,
657                                            ExplodedNode *FromN,
658                                            bool MarkAsSink) {
659  HasGeneratedNodes = true;
660  bool IsNew;
661  ExplodedNode *N = C.Eng.G.getNode(Loc, State, MarkAsSink, &IsNew);
662  N->addPredecessor(FromN, C.Eng.G);
663  Frontier.erase(FromN);
664
665  if (!IsNew)
666    return nullptr;
667
668  if (!MarkAsSink)
669    Frontier.Add(N);
670
671  return N;
672}
673
674void NodeBuilderWithSinks::anchor() { }
675
676StmtNodeBuilder::~StmtNodeBuilder() {
677  if (EnclosingBldr)
678    for (ExplodedNodeSet::iterator I = Frontier.begin(),
679                                   E = Frontier.end(); I != E; ++I )
680      EnclosingBldr->addNodes(*I);
681}
682
683void BranchNodeBuilder::anchor() { }
684
685ExplodedNode *BranchNodeBuilder::generateNode(ProgramStateRef State,
686                                              bool branch,
687                                              ExplodedNode *NodePred) {
688  // If the branch has been marked infeasible we should not generate a node.
689  if (!isFeasible(branch))
690    return nullptr;
691
692  ProgramPoint Loc = BlockEdge(C.Block, branch ? DstT:DstF,
693                               NodePred->getLocationContext());
694  ExplodedNode *Succ = generateNodeImpl(Loc, State, NodePred);
695  return Succ;
696}
697
698ExplodedNode*
699IndirectGotoNodeBuilder::generateNode(const iterator &I,
700                                      ProgramStateRef St,
701                                      bool IsSink) {
702  bool IsNew;
703  ExplodedNode *Succ =
704      Eng.G.getNode(BlockEdge(Src, I.getBlock(), Pred->getLocationContext()),
705                    St, IsSink, &IsNew);
706  Succ->addPredecessor(Pred, Eng.G);
707
708  if (!IsNew)
709    return nullptr;
710
711  if (!IsSink)
712    Eng.WList->enqueue(Succ);
713
714  return Succ;
715}
716
717
718ExplodedNode*
719SwitchNodeBuilder::generateCaseStmtNode(const iterator &I,
720                                        ProgramStateRef St) {
721
722  bool IsNew;
723  ExplodedNode *Succ =
724      Eng.G.getNode(BlockEdge(Src, I.getBlock(), Pred->getLocationContext()),
725                    St, false, &IsNew);
726  Succ->addPredecessor(Pred, Eng.G);
727  if (!IsNew)
728    return nullptr;
729
730  Eng.WList->enqueue(Succ);
731  return Succ;
732}
733
734
735ExplodedNode*
736SwitchNodeBuilder::generateDefaultCaseNode(ProgramStateRef St,
737                                           bool IsSink) {
738  // Get the block for the default case.
739  assert(Src->succ_rbegin() != Src->succ_rend());
740  CFGBlock *DefaultBlock = *Src->succ_rbegin();
741
742  // Sanity check for default blocks that are unreachable and not caught
743  // by earlier stages.
744  if (!DefaultBlock)
745    return nullptr;
746
747  bool IsNew;
748  ExplodedNode *Succ =
749      Eng.G.getNode(BlockEdge(Src, DefaultBlock, Pred->getLocationContext()),
750                    St, IsSink, &IsNew);
751  Succ->addPredecessor(Pred, Eng.G);
752
753  if (!IsNew)
754    return nullptr;
755
756  if (!IsSink)
757    Eng.WList->enqueue(Succ);
758
759  return Succ;
760}
761