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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/DenseMap.h"
22 #include "llvm/ADT/Statistic.h"
23 #include "llvm/Support/Casting.h"
24 
25 using namespace clang;
26 using namespace ento;
27 
28 #define DEBUG_TYPE "CoreEngine"
29 
30 STATISTIC(NumSteps,
31             "The # of steps executed.");
32 STATISTIC(NumReachedMaxSteps,
33             "The # of times we reached the max number of steps.");
34 STATISTIC(NumPathsExplored,
35             "The # of paths explored by the analyzer.");
36 
37 //===----------------------------------------------------------------------===//
38 // Worklist classes for exploration of reachable states.
39 //===----------------------------------------------------------------------===//
40 
~Visitor()41 WorkList::Visitor::~Visitor() {}
42 
43 namespace {
44 class DFS : public WorkList {
45   SmallVector<WorkListUnit,20> Stack;
46 public:
hasWork() const47   bool hasWork() const override {
48     return !Stack.empty();
49   }
50 
enqueue(const WorkListUnit & U)51   void enqueue(const WorkListUnit& U) override {
52     Stack.push_back(U);
53   }
54 
dequeue()55   WorkListUnit dequeue() override {
56     assert (!Stack.empty());
57     const WorkListUnit& U = Stack.back();
58     Stack.pop_back(); // This technically "invalidates" U, but we are fine.
59     return U;
60   }
61 
visitItemsInWorkList(Visitor & V)62   bool visitItemsInWorkList(Visitor &V) override {
63     for (SmallVectorImpl<WorkListUnit>::iterator
64          I = Stack.begin(), E = Stack.end(); I != E; ++I) {
65       if (V.visit(*I))
66         return true;
67     }
68     return false;
69   }
70 };
71 
72 class BFS : public WorkList {
73   std::deque<WorkListUnit> Queue;
74 public:
hasWork() const75   bool hasWork() const override {
76     return !Queue.empty();
77   }
78 
enqueue(const WorkListUnit & U)79   void enqueue(const WorkListUnit& U) override {
80     Queue.push_back(U);
81   }
82 
dequeue()83   WorkListUnit dequeue() override {
84     WorkListUnit U = Queue.front();
85     Queue.pop_front();
86     return U;
87   }
88 
visitItemsInWorkList(Visitor & V)89   bool visitItemsInWorkList(Visitor &V) override {
90     for (std::deque<WorkListUnit>::iterator
91          I = Queue.begin(), E = Queue.end(); I != E; ++I) {
92       if (V.visit(*I))
93         return true;
94     }
95     return false;
96   }
97 };
98 
99 } // end anonymous namespace
100 
101 // Place the dstor for WorkList here because it contains virtual member
102 // functions, and we the code for the dstor generated in one compilation unit.
~WorkList()103 WorkList::~WorkList() {}
104 
makeDFS()105 WorkList *WorkList::makeDFS() { return new DFS(); }
makeBFS()106 WorkList *WorkList::makeBFS() { return new BFS(); }
107 
108 namespace {
109   class BFSBlockDFSContents : public WorkList {
110     std::deque<WorkListUnit> Queue;
111     SmallVector<WorkListUnit,20> Stack;
112   public:
hasWork() const113     bool hasWork() const override {
114       return !Queue.empty() || !Stack.empty();
115     }
116 
enqueue(const WorkListUnit & U)117     void enqueue(const WorkListUnit& U) override {
118       if (U.getNode()->getLocation().getAs<BlockEntrance>())
119         Queue.push_front(U);
120       else
121         Stack.push_back(U);
122     }
123 
dequeue()124     WorkListUnit dequeue() override {
125       // Process all basic blocks to completion.
126       if (!Stack.empty()) {
127         const WorkListUnit& U = Stack.back();
128         Stack.pop_back(); // This technically "invalidates" U, but we are fine.
129         return U;
130       }
131 
132       assert(!Queue.empty());
133       // Don't use const reference.  The subsequent pop_back() might make it
134       // unsafe.
135       WorkListUnit U = Queue.front();
136       Queue.pop_front();
137       return U;
138     }
visitItemsInWorkList(Visitor & V)139     bool visitItemsInWorkList(Visitor &V) override {
140       for (SmallVectorImpl<WorkListUnit>::iterator
141            I = Stack.begin(), E = Stack.end(); I != E; ++I) {
142         if (V.visit(*I))
143           return true;
144       }
145       for (std::deque<WorkListUnit>::iterator
146            I = Queue.begin(), E = Queue.end(); I != E; ++I) {
147         if (V.visit(*I))
148           return true;
149       }
150       return false;
151     }
152 
153   };
154 } // end anonymous namespace
155 
makeBFSBlockDFSContents()156 WorkList* WorkList::makeBFSBlockDFSContents() {
157   return new BFSBlockDFSContents();
158 }
159 
160 //===----------------------------------------------------------------------===//
161 // Core analysis engine.
162 //===----------------------------------------------------------------------===//
163 
164 /// ExecuteWorkList - Run the worklist algorithm for a maximum number of steps.
ExecuteWorkList(const LocationContext * L,unsigned Steps,ProgramStateRef InitState)165 bool CoreEngine::ExecuteWorkList(const LocationContext *L, unsigned Steps,
166                                    ProgramStateRef InitState) {
167 
168   if (G.num_roots() == 0) { // Initialize the analysis by constructing
169     // the root if none exists.
170 
171     const CFGBlock *Entry = &(L->getCFG()->getEntry());
172 
173     assert (Entry->empty() &&
174             "Entry block must be empty.");
175 
176     assert (Entry->succ_size() == 1 &&
177             "Entry block must have 1 successor.");
178 
179     // Mark the entry block as visited.
180     FunctionSummaries->markVisitedBasicBlock(Entry->getBlockID(),
181                                              L->getDecl(),
182                                              L->getCFG()->getNumBlockIDs());
183 
184     // Get the solitary successor.
185     const CFGBlock *Succ = *(Entry->succ_begin());
186 
187     // Construct an edge representing the
188     // starting location in the function.
189     BlockEdge StartLoc(Entry, Succ, L);
190 
191     // Set the current block counter to being empty.
192     WList->setBlockCounter(BCounterFactory.GetEmptyCounter());
193 
194     if (!InitState)
195       InitState = SubEng.getInitialState(L);
196 
197     bool IsNew;
198     ExplodedNode *Node = G.getNode(StartLoc, InitState, false, &IsNew);
199     assert (IsNew);
200     G.addRoot(Node);
201 
202     NodeBuilderContext BuilderCtx(*this, StartLoc.getDst(), Node);
203     ExplodedNodeSet DstBegin;
204     SubEng.processBeginOfFunction(BuilderCtx, Node, DstBegin, StartLoc);
205 
206     enqueue(DstBegin);
207   }
208 
209   // Check if we have a steps limit
210   bool UnlimitedSteps = Steps == 0;
211   // Cap our pre-reservation in the event that the user specifies
212   // a very large number of maximum steps.
213   const unsigned PreReservationCap = 4000000;
214   if(!UnlimitedSteps)
215     G.reserve(std::min(Steps,PreReservationCap));
216 
217   while (WList->hasWork()) {
218     if (!UnlimitedSteps) {
219       if (Steps == 0) {
220         NumReachedMaxSteps++;
221         break;
222       }
223       --Steps;
224     }
225 
226     NumSteps++;
227 
228     const WorkListUnit& WU = WList->dequeue();
229 
230     // Set the current block counter.
231     WList->setBlockCounter(WU.getBlockCounter());
232 
233     // Retrieve the node.
234     ExplodedNode *Node = WU.getNode();
235 
236     dispatchWorkItem(Node, Node->getLocation(), WU);
237   }
238   SubEng.processEndWorklist(hasWorkRemaining());
239   return WList->hasWork();
240 }
241 
dispatchWorkItem(ExplodedNode * Pred,ProgramPoint Loc,const WorkListUnit & WU)242 void CoreEngine::dispatchWorkItem(ExplodedNode* Pred, ProgramPoint Loc,
243                                   const WorkListUnit& WU) {
244   // Dispatch on the location type.
245   switch (Loc.getKind()) {
246     case ProgramPoint::BlockEdgeKind:
247       HandleBlockEdge(Loc.castAs<BlockEdge>(), Pred);
248       break;
249 
250     case ProgramPoint::BlockEntranceKind:
251       HandleBlockEntrance(Loc.castAs<BlockEntrance>(), Pred);
252       break;
253 
254     case ProgramPoint::BlockExitKind:
255       assert (false && "BlockExit location never occur in forward analysis.");
256       break;
257 
258     case ProgramPoint::CallEnterKind: {
259       HandleCallEnter(Loc.castAs<CallEnter>(), Pred);
260       break;
261     }
262 
263     case ProgramPoint::CallExitBeginKind:
264       SubEng.processCallExit(Pred);
265       break;
266 
267     case ProgramPoint::EpsilonKind: {
268       assert(Pred->hasSinglePred() &&
269              "Assume epsilon has exactly one predecessor by construction");
270       ExplodedNode *PNode = Pred->getFirstPred();
271       dispatchWorkItem(Pred, PNode->getLocation(), WU);
272       break;
273     }
274     default:
275       assert(Loc.getAs<PostStmt>() ||
276              Loc.getAs<PostInitializer>() ||
277              Loc.getAs<PostImplicitCall>() ||
278              Loc.getAs<CallExitEnd>());
279       HandlePostStmt(WU.getBlock(), WU.getIndex(), Pred);
280       break;
281   }
282 }
283 
ExecuteWorkListWithInitialState(const LocationContext * L,unsigned Steps,ProgramStateRef InitState,ExplodedNodeSet & Dst)284 bool 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 
HandleBlockEdge(const BlockEdge & L,ExplodedNode * Pred)296 void 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     // Process the final state transition.
314     SubEng.processEndOfFunction(BuilderCtx, Pred);
315 
316     // This path is done. Don't enqueue any more nodes.
317     return;
318   }
319 
320   // Call into the SubEngine to process entering the CFGBlock.
321   ExplodedNodeSet dstNodes;
322   BlockEntrance BE(Blk, Pred->getLocationContext());
323   NodeBuilderWithSinks nodeBuilder(Pred, dstNodes, BuilderCtx, BE);
324   SubEng.processCFGBlockEntrance(L, nodeBuilder, Pred);
325 
326   // Auto-generate a node.
327   if (!nodeBuilder.hasGeneratedNodes()) {
328     nodeBuilder.generateNode(Pred->State, Pred);
329   }
330 
331   // Enqueue nodes onto the worklist.
332   enqueue(dstNodes);
333 }
334 
HandleBlockEntrance(const BlockEntrance & L,ExplodedNode * Pred)335 void CoreEngine::HandleBlockEntrance(const BlockEntrance &L,
336                                        ExplodedNode *Pred) {
337 
338   // Increment the block counter.
339   const LocationContext *LC = Pred->getLocationContext();
340   unsigned BlockId = L.getBlock()->getBlockID();
341   BlockCounter Counter = WList->getBlockCounter();
342   Counter = BCounterFactory.IncrementCount(Counter, LC->getCurrentStackFrame(),
343                                            BlockId);
344   WList->setBlockCounter(Counter);
345 
346   // Process the entrance of the block.
347   if (Optional<CFGElement> E = L.getFirstElement()) {
348     NodeBuilderContext Ctx(*this, L.getBlock(), Pred);
349     SubEng.processCFGElement(*E, Pred, 0, &Ctx);
350   }
351   else
352     HandleBlockExit(L.getBlock(), Pred);
353 }
354 
HandleBlockExit(const CFGBlock * B,ExplodedNode * Pred)355 void CoreEngine::HandleBlockExit(const CFGBlock * B, ExplodedNode *Pred) {
356 
357   if (const Stmt *Term = B->getTerminator()) {
358     switch (Term->getStmtClass()) {
359       default:
360         llvm_unreachable("Analysis for this terminator not implemented.");
361 
362       case Stmt::CXXBindTemporaryExprClass:
363         HandleCleanupTemporaryBranch(
364             cast<CXXBindTemporaryExpr>(B->getTerminator().getStmt()), B, Pred);
365         return;
366 
367       // Model static initializers.
368       case Stmt::DeclStmtClass:
369         HandleStaticInit(cast<DeclStmt>(Term), B, Pred);
370         return;
371 
372       case Stmt::BinaryOperatorClass: // '&&' and '||'
373         HandleBranch(cast<BinaryOperator>(Term)->getLHS(), Term, B, Pred);
374         return;
375 
376       case Stmt::BinaryConditionalOperatorClass:
377       case Stmt::ConditionalOperatorClass:
378         HandleBranch(cast<AbstractConditionalOperator>(Term)->getCond(),
379                      Term, B, Pred);
380         return;
381 
382         // FIXME: Use constant-folding in CFG construction to simplify this
383         // case.
384 
385       case Stmt::ChooseExprClass:
386         HandleBranch(cast<ChooseExpr>(Term)->getCond(), Term, B, Pred);
387         return;
388 
389       case Stmt::CXXTryStmtClass: {
390         // Generate a node for each of the successors.
391         // Our logic for EH analysis can certainly be improved.
392         for (CFGBlock::const_succ_iterator it = B->succ_begin(),
393              et = B->succ_end(); it != et; ++it) {
394           if (const CFGBlock *succ = *it) {
395             generateNode(BlockEdge(B, succ, Pred->getLocationContext()),
396                          Pred->State, Pred);
397           }
398         }
399         return;
400       }
401 
402       case Stmt::DoStmtClass:
403         HandleBranch(cast<DoStmt>(Term)->getCond(), Term, B, Pred);
404         return;
405 
406       case Stmt::CXXForRangeStmtClass:
407         HandleBranch(cast<CXXForRangeStmt>(Term)->getCond(), Term, B, Pred);
408         return;
409 
410       case Stmt::ForStmtClass:
411         HandleBranch(cast<ForStmt>(Term)->getCond(), Term, B, Pred);
412         return;
413 
414       case Stmt::ContinueStmtClass:
415       case Stmt::BreakStmtClass:
416       case Stmt::GotoStmtClass:
417         break;
418 
419       case Stmt::IfStmtClass:
420         HandleBranch(cast<IfStmt>(Term)->getCond(), Term, B, Pred);
421         return;
422 
423       case Stmt::IndirectGotoStmtClass: {
424         // Only 1 successor: the indirect goto dispatch block.
425         assert (B->succ_size() == 1);
426 
427         IndirectGotoNodeBuilder
428            builder(Pred, B, cast<IndirectGotoStmt>(Term)->getTarget(),
429                    *(B->succ_begin()), this);
430 
431         SubEng.processIndirectGoto(builder);
432         return;
433       }
434 
435       case Stmt::ObjCForCollectionStmtClass: {
436         // In the case of ObjCForCollectionStmt, it appears twice in a CFG:
437         //
438         //  (1) inside a basic block, which represents the binding of the
439         //      'element' variable to a value.
440         //  (2) in a terminator, which represents the branch.
441         //
442         // For (1), subengines will bind a value (i.e., 0 or 1) indicating
443         // whether or not collection contains any more elements.  We cannot
444         // just test to see if the element is nil because a container can
445         // contain nil elements.
446         HandleBranch(Term, Term, B, Pred);
447         return;
448       }
449 
450       case Stmt::SwitchStmtClass: {
451         SwitchNodeBuilder builder(Pred, B, cast<SwitchStmt>(Term)->getCond(),
452                                     this);
453 
454         SubEng.processSwitch(builder);
455         return;
456       }
457 
458       case Stmt::WhileStmtClass:
459         HandleBranch(cast<WhileStmt>(Term)->getCond(), Term, B, Pred);
460         return;
461     }
462   }
463 
464   assert (B->succ_size() == 1 &&
465           "Blocks with no terminator should have at most 1 successor.");
466 
467   generateNode(BlockEdge(B, *(B->succ_begin()), Pred->getLocationContext()),
468                Pred->State, Pred);
469 }
470 
HandleCallEnter(const CallEnter & CE,ExplodedNode * Pred)471 void CoreEngine::HandleCallEnter(const CallEnter &CE, ExplodedNode *Pred) {
472   NodeBuilderContext BuilderCtx(*this, CE.getEntry(), Pred);
473   SubEng.processCallEnter(BuilderCtx, CE, Pred);
474 }
475 
HandleBranch(const Stmt * Cond,const Stmt * Term,const CFGBlock * B,ExplodedNode * Pred)476 void CoreEngine::HandleBranch(const Stmt *Cond, const Stmt *Term,
477                                 const CFGBlock * B, ExplodedNode *Pred) {
478   assert(B->succ_size() == 2);
479   NodeBuilderContext Ctx(*this, B, Pred);
480   ExplodedNodeSet Dst;
481   SubEng.processBranch(Cond, Term, Ctx, Pred, Dst,
482                        *(B->succ_begin()), *(B->succ_begin()+1));
483   // Enqueue the new frontier onto the worklist.
484   enqueue(Dst);
485 }
486 
HandleCleanupTemporaryBranch(const CXXBindTemporaryExpr * BTE,const CFGBlock * B,ExplodedNode * Pred)487 void CoreEngine::HandleCleanupTemporaryBranch(const CXXBindTemporaryExpr *BTE,
488                                               const CFGBlock *B,
489                                               ExplodedNode *Pred) {
490   assert(B->succ_size() == 2);
491   NodeBuilderContext Ctx(*this, B, Pred);
492   ExplodedNodeSet Dst;
493   SubEng.processCleanupTemporaryBranch(BTE, Ctx, Pred, Dst, *(B->succ_begin()),
494                                        *(B->succ_begin() + 1));
495   // Enqueue the new frontier onto the worklist.
496   enqueue(Dst);
497 }
498 
HandleStaticInit(const DeclStmt * DS,const CFGBlock * B,ExplodedNode * Pred)499 void CoreEngine::HandleStaticInit(const DeclStmt *DS, const CFGBlock *B,
500                                   ExplodedNode *Pred) {
501   assert(B->succ_size() == 2);
502   NodeBuilderContext Ctx(*this, B, Pred);
503   ExplodedNodeSet Dst;
504   SubEng.processStaticInitializer(DS, Ctx, Pred, Dst,
505                                   *(B->succ_begin()), *(B->succ_begin()+1));
506   // Enqueue the new frontier onto the worklist.
507   enqueue(Dst);
508 }
509 
510 
HandlePostStmt(const CFGBlock * B,unsigned StmtIdx,ExplodedNode * Pred)511 void CoreEngine::HandlePostStmt(const CFGBlock *B, unsigned StmtIdx,
512                                   ExplodedNode *Pred) {
513   assert(B);
514   assert(!B->empty());
515 
516   if (StmtIdx == B->size())
517     HandleBlockExit(B, Pred);
518   else {
519     NodeBuilderContext Ctx(*this, B, Pred);
520     SubEng.processCFGElement((*B)[StmtIdx], Pred, StmtIdx, &Ctx);
521   }
522 }
523 
524 /// generateNode - Utility method to generate nodes, hook up successors,
525 ///  and add nodes to the worklist.
generateNode(const ProgramPoint & Loc,ProgramStateRef State,ExplodedNode * Pred)526 void CoreEngine::generateNode(const ProgramPoint &Loc,
527                               ProgramStateRef State,
528                               ExplodedNode *Pred) {
529 
530   bool IsNew;
531   ExplodedNode *Node = G.getNode(Loc, State, false, &IsNew);
532 
533   if (Pred)
534     Node->addPredecessor(Pred, G); // Link 'Node' with its predecessor.
535   else {
536     assert (IsNew);
537     G.addRoot(Node); // 'Node' has no predecessor.  Make it a root.
538   }
539 
540   // Only add 'Node' to the worklist if it was freshly generated.
541   if (IsNew) WList->enqueue(Node);
542 }
543 
enqueueStmtNode(ExplodedNode * N,const CFGBlock * Block,unsigned Idx)544 void CoreEngine::enqueueStmtNode(ExplodedNode *N,
545                                  const CFGBlock *Block, unsigned Idx) {
546   assert(Block);
547   assert (!N->isSink());
548 
549   // Check if this node entered a callee.
550   if (N->getLocation().getAs<CallEnter>()) {
551     // Still use the index of the CallExpr. It's needed to create the callee
552     // StackFrameContext.
553     WList->enqueue(N, Block, Idx);
554     return;
555   }
556 
557   // Do not create extra nodes. Move to the next CFG element.
558   if (N->getLocation().getAs<PostInitializer>() ||
559       N->getLocation().getAs<PostImplicitCall>()) {
560     WList->enqueue(N, Block, Idx+1);
561     return;
562   }
563 
564   if (N->getLocation().getAs<EpsilonPoint>()) {
565     WList->enqueue(N, Block, Idx);
566     return;
567   }
568 
569   if ((*Block)[Idx].getKind() == CFGElement::NewAllocator) {
570     WList->enqueue(N, Block, Idx+1);
571     return;
572   }
573 
574   // At this point, we know we're processing a normal statement.
575   CFGStmt CS = (*Block)[Idx].castAs<CFGStmt>();
576   PostStmt Loc(CS.getStmt(), N->getLocationContext());
577 
578   if (Loc == N->getLocation().withTag(nullptr)) {
579     // Note: 'N' should be a fresh node because otherwise it shouldn't be
580     // a member of Deferred.
581     WList->enqueue(N, Block, Idx+1);
582     return;
583   }
584 
585   bool IsNew;
586   ExplodedNode *Succ = G.getNode(Loc, N->getState(), false, &IsNew);
587   Succ->addPredecessor(N, G);
588 
589   if (IsNew)
590     WList->enqueue(Succ, Block, Idx+1);
591 }
592 
generateCallExitBeginNode(ExplodedNode * N)593 ExplodedNode *CoreEngine::generateCallExitBeginNode(ExplodedNode *N) {
594   // Create a CallExitBegin node and enqueue it.
595   const StackFrameContext *LocCtx
596                          = cast<StackFrameContext>(N->getLocationContext());
597 
598   // Use the callee location context.
599   CallExitBegin Loc(LocCtx);
600 
601   bool isNew;
602   ExplodedNode *Node = G.getNode(Loc, N->getState(), false, &isNew);
603   Node->addPredecessor(N, G);
604   return isNew ? Node : nullptr;
605 }
606 
607 
enqueue(ExplodedNodeSet & Set)608 void CoreEngine::enqueue(ExplodedNodeSet &Set) {
609   for (ExplodedNodeSet::iterator I = Set.begin(),
610                                  E = Set.end(); I != E; ++I) {
611     WList->enqueue(*I);
612   }
613 }
614 
enqueue(ExplodedNodeSet & Set,const CFGBlock * Block,unsigned Idx)615 void CoreEngine::enqueue(ExplodedNodeSet &Set,
616                          const CFGBlock *Block, unsigned Idx) {
617   for (ExplodedNodeSet::iterator I = Set.begin(),
618                                  E = Set.end(); I != E; ++I) {
619     enqueueStmtNode(*I, Block, Idx);
620   }
621 }
622 
enqueueEndOfFunction(ExplodedNodeSet & Set)623 void CoreEngine::enqueueEndOfFunction(ExplodedNodeSet &Set) {
624   for (ExplodedNodeSet::iterator I = Set.begin(), E = Set.end(); I != E; ++I) {
625     ExplodedNode *N = *I;
626     // If we are in an inlined call, generate CallExitBegin node.
627     if (N->getLocationContext()->getParent()) {
628       N = generateCallExitBeginNode(N);
629       if (N)
630         WList->enqueue(N);
631     } else {
632       // TODO: We should run remove dead bindings here.
633       G.addEndOfPath(N);
634       NumPathsExplored++;
635     }
636   }
637 }
638 
639 
anchor()640 void NodeBuilder::anchor() { }
641 
generateNodeImpl(const ProgramPoint & Loc,ProgramStateRef State,ExplodedNode * FromN,bool MarkAsSink)642 ExplodedNode* NodeBuilder::generateNodeImpl(const ProgramPoint &Loc,
643                                             ProgramStateRef State,
644                                             ExplodedNode *FromN,
645                                             bool MarkAsSink) {
646   HasGeneratedNodes = true;
647   bool IsNew;
648   ExplodedNode *N = C.Eng.G.getNode(Loc, State, MarkAsSink, &IsNew);
649   N->addPredecessor(FromN, C.Eng.G);
650   Frontier.erase(FromN);
651 
652   if (!IsNew)
653     return nullptr;
654 
655   if (!MarkAsSink)
656     Frontier.Add(N);
657 
658   return N;
659 }
660 
anchor()661 void NodeBuilderWithSinks::anchor() { }
662 
~StmtNodeBuilder()663 StmtNodeBuilder::~StmtNodeBuilder() {
664   if (EnclosingBldr)
665     for (ExplodedNodeSet::iterator I = Frontier.begin(),
666                                    E = Frontier.end(); I != E; ++I )
667       EnclosingBldr->addNodes(*I);
668 }
669 
anchor()670 void BranchNodeBuilder::anchor() { }
671 
generateNode(ProgramStateRef State,bool branch,ExplodedNode * NodePred)672 ExplodedNode *BranchNodeBuilder::generateNode(ProgramStateRef State,
673                                               bool branch,
674                                               ExplodedNode *NodePred) {
675   // If the branch has been marked infeasible we should not generate a node.
676   if (!isFeasible(branch))
677     return nullptr;
678 
679   ProgramPoint Loc = BlockEdge(C.Block, branch ? DstT:DstF,
680                                NodePred->getLocationContext());
681   ExplodedNode *Succ = generateNodeImpl(Loc, State, NodePred);
682   return Succ;
683 }
684 
685 ExplodedNode*
generateNode(const iterator & I,ProgramStateRef St,bool IsSink)686 IndirectGotoNodeBuilder::generateNode(const iterator &I,
687                                       ProgramStateRef St,
688                                       bool IsSink) {
689   bool IsNew;
690   ExplodedNode *Succ =
691       Eng.G.getNode(BlockEdge(Src, I.getBlock(), Pred->getLocationContext()),
692                     St, IsSink, &IsNew);
693   Succ->addPredecessor(Pred, Eng.G);
694 
695   if (!IsNew)
696     return nullptr;
697 
698   if (!IsSink)
699     Eng.WList->enqueue(Succ);
700 
701   return Succ;
702 }
703 
704 
705 ExplodedNode*
generateCaseStmtNode(const iterator & I,ProgramStateRef St)706 SwitchNodeBuilder::generateCaseStmtNode(const iterator &I,
707                                         ProgramStateRef St) {
708 
709   bool IsNew;
710   ExplodedNode *Succ =
711       Eng.G.getNode(BlockEdge(Src, I.getBlock(), Pred->getLocationContext()),
712                     St, false, &IsNew);
713   Succ->addPredecessor(Pred, Eng.G);
714   if (!IsNew)
715     return nullptr;
716 
717   Eng.WList->enqueue(Succ);
718   return Succ;
719 }
720 
721 
722 ExplodedNode*
generateDefaultCaseNode(ProgramStateRef St,bool IsSink)723 SwitchNodeBuilder::generateDefaultCaseNode(ProgramStateRef St,
724                                            bool IsSink) {
725   // Get the block for the default case.
726   assert(Src->succ_rbegin() != Src->succ_rend());
727   CFGBlock *DefaultBlock = *Src->succ_rbegin();
728 
729   // Sanity check for default blocks that are unreachable and not caught
730   // by earlier stages.
731   if (!DefaultBlock)
732     return nullptr;
733 
734   bool IsNew;
735   ExplodedNode *Succ =
736       Eng.G.getNode(BlockEdge(Src, DefaultBlock, Pred->getLocationContext()),
737                     St, IsSink, &IsNew);
738   Succ->addPredecessor(Pred, Eng.G);
739 
740   if (!IsNew)
741     return nullptr;
742 
743   if (!IsSink)
744     Eng.WList->enqueue(Succ);
745 
746   return Succ;
747 }
748