1 //=-- ExplodedGraph.h - Local, Path-Sens. "Exploded Graph" -*- C++ -*-------==//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the template classes ExplodedNode and ExplodedGraph,
11 // which represent a path-sensitive, intra-procedural "exploded graph."
12 // See "Precise interprocedural dataflow analysis via graph reachability"
13 // by Reps, Horwitz, and Sagiv
14 // (http://portal.acm.org/citation.cfm?id=199462) for the definition of an
17 //===----------------------------------------------------------------------===//
19 #ifndef LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_EXPLODEDGRAPH_H
20 #define LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_EXPLODEDGRAPH_H
22 #include "clang/AST/Decl.h"
23 #include "clang/Analysis/AnalysisContext.h"
24 #include "clang/Analysis/ProgramPoint.h"
25 #include "clang/Analysis/Support/BumpVector.h"
26 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
27 #include "llvm/ADT/DepthFirstIterator.h"
28 #include "llvm/ADT/FoldingSet.h"
29 #include "llvm/ADT/GraphTraits.h"
30 #include "llvm/ADT/SmallPtrSet.h"
31 #include "llvm/ADT/SmallVector.h"
32 #include "llvm/Support/Allocator.h"
33 #include "llvm/Support/Casting.h"
45 //===----------------------------------------------------------------------===//
46 // ExplodedGraph "implementation" classes. These classes are not typed to
47 // contain a specific kind of state. Typed-specialized versions are defined
48 // on top of these classes.
49 //===----------------------------------------------------------------------===//
51 // ExplodedNode is not constified all over the engine because we need to add
52 // successors to it at any time after creating it.
54 class ExplodedNode : public llvm::FoldingSetNode {
55 friend class ExplodedGraph;
56 friend class CoreEngine;
57 friend class NodeBuilder;
58 friend class BranchNodeBuilder;
59 friend class IndirectGotoNodeBuilder;
60 friend class SwitchNodeBuilder;
61 friend class EndOfFunctionNodeBuilder;
63 /// Efficiently stores a list of ExplodedNodes, or an optional flag.
65 /// NodeGroup provides opaque storage for a list of ExplodedNodes, optimizing
66 /// for the case when there is only one node in the group. This is a fairly
67 /// common case in an ExplodedGraph, where most nodes have only one
68 /// predecessor and many have only one successor. It can also be used to
69 /// store a flag rather than a node list, which ExplodedNode uses to mark
70 /// whether a node is a sink. If the flag is set, the group is implicitly
71 /// empty and no nodes may be added.
73 // Conceptually a discriminated union. If the low bit is set, the node is
74 // a sink. If the low bit is not set, the pointer refers to the storage
75 // for the nodes in the group.
76 // This is not a PointerIntPair in order to keep the storage type opaque.
80 NodeGroup(bool Flag = false) : P(Flag) {
81 assert(getFlag() == Flag);
84 ExplodedNode * const *begin() const;
86 ExplodedNode * const *end() const;
88 unsigned size() const;
90 bool empty() const { return P == 0 || getFlag() != 0; }
92 /// Adds a node to the list.
94 /// The group must not have been created with its flag set.
95 void addNode(ExplodedNode *N, ExplodedGraph &G);
97 /// Replaces the single node in this group with a new node.
99 /// Note that this should only be used when you know the group was not
100 /// created with its flag set, and that the group is empty or contains
101 /// only a single node.
102 void replaceNode(ExplodedNode *node);
104 /// Returns whether this group was created with its flag set.
105 bool getFlag() const {
110 /// Location - The program location (within a function body) associated
112 const ProgramPoint Location;
114 /// State - The state associated with this node.
115 ProgramStateRef State;
117 /// Preds - The predecessors of this node.
120 /// Succs - The successors of this node.
125 explicit ExplodedNode(const ProgramPoint &loc, ProgramStateRef state,
127 : Location(loc), State(state), Succs(IsSink) {
128 assert(isSink() == IsSink);
131 /// getLocation - Returns the edge associated with the given node.
132 ProgramPoint getLocation() const { return Location; }
134 const LocationContext *getLocationContext() const {
135 return getLocation().getLocationContext();
138 const StackFrameContext *getStackFrame() const {
139 return getLocationContext()->getCurrentStackFrame();
142 const Decl &getCodeDecl() const { return *getLocationContext()->getDecl(); }
144 CFG &getCFG() const { return *getLocationContext()->getCFG(); }
146 ParentMap &getParentMap() const {return getLocationContext()->getParentMap();}
148 template <typename T>
149 T &getAnalysis() const {
150 return *getLocationContext()->getAnalysis<T>();
153 const ProgramStateRef &getState() const { return State; }
155 template <typename T>
156 Optional<T> getLocationAs() const LLVM_LVALUE_FUNCTION {
157 return Location.getAs<T>();
160 static void Profile(llvm::FoldingSetNodeID &ID,
161 const ProgramPoint &Loc,
162 const ProgramStateRef &state,
165 ID.AddPointer(state.get());
166 ID.AddBoolean(IsSink);
169 void Profile(llvm::FoldingSetNodeID& ID) const {
170 // We avoid copy constructors by not using accessors.
171 Profile(ID, Location, State, isSink());
174 /// addPredeccessor - Adds a predecessor to the current node, and
175 /// in tandem add this node as a successor of the other node.
176 void addPredecessor(ExplodedNode *V, ExplodedGraph &G);
178 unsigned succ_size() const { return Succs.size(); }
179 unsigned pred_size() const { return Preds.size(); }
180 bool succ_empty() const { return Succs.empty(); }
181 bool pred_empty() const { return Preds.empty(); }
183 bool isSink() const { return Succs.getFlag(); }
185 bool hasSinglePred() const {
186 return (pred_size() == 1);
189 ExplodedNode *getFirstPred() {
190 return pred_empty() ? nullptr : *(pred_begin());
193 const ExplodedNode *getFirstPred() const {
194 return const_cast<ExplodedNode*>(this)->getFirstPred();
197 const ExplodedNode *getFirstSucc() const {
198 return succ_empty() ? nullptr : *(succ_begin());
201 // Iterators over successor and predecessor vertices.
202 typedef ExplodedNode* const * succ_iterator;
203 typedef const ExplodedNode* const * const_succ_iterator;
204 typedef ExplodedNode* const * pred_iterator;
205 typedef const ExplodedNode* const * const_pred_iterator;
207 pred_iterator pred_begin() { return Preds.begin(); }
208 pred_iterator pred_end() { return Preds.end(); }
210 const_pred_iterator pred_begin() const {
211 return const_cast<ExplodedNode*>(this)->pred_begin();
213 const_pred_iterator pred_end() const {
214 return const_cast<ExplodedNode*>(this)->pred_end();
217 succ_iterator succ_begin() { return Succs.begin(); }
218 succ_iterator succ_end() { return Succs.end(); }
220 const_succ_iterator succ_begin() const {
221 return const_cast<ExplodedNode*>(this)->succ_begin();
223 const_succ_iterator succ_end() const {
224 return const_cast<ExplodedNode*>(this)->succ_end();
234 virtual void AddEdge(ExplodedNode *Src, ExplodedNode *Dst) = 0;
237 static void SetAuditor(Auditor* A);
240 void replaceSuccessor(ExplodedNode *node) { Succs.replaceNode(node); }
241 void replacePredecessor(ExplodedNode *node) { Preds.replaceNode(node); }
244 typedef llvm::DenseMap<const ExplodedNode *, const ExplodedNode *>
245 InterExplodedGraphMap;
247 class ExplodedGraph {
249 friend class CoreEngine;
252 typedef std::vector<ExplodedNode *> NodeVector;
254 /// The roots of the simulation graph. Usually there will be only
255 /// one, but clients are free to establish multiple subgraphs within a single
256 /// SimulGraph. Moreover, these subgraphs can often merge when paths from
257 /// different roots reach the same state at the same program location.
260 /// The nodes in the simulation graph which have been
261 /// specially marked as the endpoint of an abstract simulation path.
264 /// Nodes - The nodes in the graph.
265 llvm::FoldingSet<ExplodedNode> Nodes;
267 /// BVC - Allocator and context for allocating nodes and their predecessor
268 /// and successor groups.
269 BumpVectorContext BVC;
271 /// NumNodes - The number of nodes in the graph.
274 /// A list of recently allocated nodes that can potentially be recycled.
275 NodeVector ChangedNodes;
277 /// A list of nodes that can be reused.
278 NodeVector FreeNodes;
280 /// Determines how often nodes are reclaimed.
282 /// If this is 0, nodes will never be reclaimed.
283 unsigned ReclaimNodeInterval;
285 /// Counter to determine when to reclaim nodes.
286 unsigned ReclaimCounter;
290 /// \brief Retrieve the node associated with a (Location,State) pair,
291 /// where the 'Location' is a ProgramPoint in the CFG. If no node for
292 /// this pair exists, it is created. IsNew is set to true if
293 /// the node was freshly created.
294 ExplodedNode *getNode(const ProgramPoint &L, ProgramStateRef State,
296 bool* IsNew = nullptr);
298 std::unique_ptr<ExplodedGraph> MakeEmptyGraph() const {
299 return llvm::make_unique<ExplodedGraph>();
302 /// addRoot - Add an untyped node to the set of roots.
303 ExplodedNode *addRoot(ExplodedNode *V) {
308 /// addEndOfPath - Add an untyped node to the set of EOP nodes.
309 ExplodedNode *addEndOfPath(ExplodedNode *V) {
310 EndNodes.push_back(V);
318 unsigned num_roots() const { return Roots.size(); }
319 unsigned num_eops() const { return EndNodes.size(); }
321 bool empty() const { return NumNodes == 0; }
322 unsigned size() const { return NumNodes; }
325 typedef ExplodedNode NodeTy;
326 typedef llvm::FoldingSet<ExplodedNode> AllNodesTy;
327 typedef NodeVector::iterator roots_iterator;
328 typedef NodeVector::const_iterator const_roots_iterator;
329 typedef NodeVector::iterator eop_iterator;
330 typedef NodeVector::const_iterator const_eop_iterator;
331 typedef AllNodesTy::iterator node_iterator;
332 typedef AllNodesTy::const_iterator const_node_iterator;
334 node_iterator nodes_begin() { return Nodes.begin(); }
336 node_iterator nodes_end() { return Nodes.end(); }
338 const_node_iterator nodes_begin() const { return Nodes.begin(); }
340 const_node_iterator nodes_end() const { return Nodes.end(); }
342 roots_iterator roots_begin() { return Roots.begin(); }
344 roots_iterator roots_end() { return Roots.end(); }
346 const_roots_iterator roots_begin() const { return Roots.begin(); }
348 const_roots_iterator roots_end() const { return Roots.end(); }
350 eop_iterator eop_begin() { return EndNodes.begin(); }
352 eop_iterator eop_end() { return EndNodes.end(); }
354 const_eop_iterator eop_begin() const { return EndNodes.begin(); }
356 const_eop_iterator eop_end() const { return EndNodes.end(); }
358 llvm::BumpPtrAllocator & getAllocator() { return BVC.getAllocator(); }
359 BumpVectorContext &getNodeAllocator() { return BVC; }
361 typedef llvm::DenseMap<const ExplodedNode*, ExplodedNode*> NodeMap;
363 /// Creates a trimmed version of the graph that only contains paths leading
364 /// to the given nodes.
366 /// \param Nodes The nodes which must appear in the final graph. Presumably
367 /// these are end-of-path nodes (i.e. they have no successors).
368 /// \param[out] ForwardMap A optional map from nodes in this graph to nodes in
369 /// the returned graph.
370 /// \param[out] InverseMap An optional map from nodes in the returned graph to
371 /// nodes in this graph.
372 /// \returns The trimmed graph
373 std::unique_ptr<ExplodedGraph>
374 trim(ArrayRef<const NodeTy *> Nodes,
375 InterExplodedGraphMap *ForwardMap = nullptr,
376 InterExplodedGraphMap *InverseMap = nullptr) const;
378 /// Enable tracking of recently allocated nodes for potential reclamation
379 /// when calling reclaimRecentlyAllocatedNodes().
380 void enableNodeReclamation(unsigned Interval) {
381 ReclaimCounter = ReclaimNodeInterval = Interval;
384 /// Reclaim "uninteresting" nodes created since the last time this method
386 void reclaimRecentlyAllocatedNodes();
388 /// \brief Returns true if nodes for the given expression kind are always
390 static bool isInterestingLValueExpr(const Expr *Ex);
393 bool shouldCollect(const ExplodedNode *node);
394 void collectNode(ExplodedNode *node);
397 class ExplodedNodeSet {
398 typedef llvm::SmallPtrSet<ExplodedNode*,5> ImplTy;
402 ExplodedNodeSet(ExplodedNode *N) {
403 assert (N && !static_cast<ExplodedNode*>(N)->isSink());
409 inline void Add(ExplodedNode *N) {
410 if (N && !static_cast<ExplodedNode*>(N)->isSink()) Impl.insert(N);
413 typedef ImplTy::iterator iterator;
414 typedef ImplTy::const_iterator const_iterator;
416 unsigned size() const { return Impl.size(); }
417 bool empty() const { return Impl.empty(); }
418 bool erase(ExplodedNode *N) { return Impl.erase(N); }
420 void clear() { Impl.clear(); }
421 void insert(const ExplodedNodeSet &S) {
426 Impl.insert(S.begin(), S.end());
429 inline iterator begin() { return Impl.begin(); }
430 inline iterator end() { return Impl.end(); }
432 inline const_iterator begin() const { return Impl.begin(); }
433 inline const_iterator end() const { return Impl.end(); }
436 } // end GR namespace
438 } // end clang namespace
443 template<> struct GraphTraits<clang::ento::ExplodedNode*> {
444 typedef clang::ento::ExplodedNode NodeType;
445 typedef NodeType::succ_iterator ChildIteratorType;
446 typedef llvm::df_iterator<NodeType*> nodes_iterator;
448 static inline NodeType* getEntryNode(NodeType* N) {
452 static inline ChildIteratorType child_begin(NodeType* N) {
453 return N->succ_begin();
456 static inline ChildIteratorType child_end(NodeType* N) {
457 return N->succ_end();
460 static inline nodes_iterator nodes_begin(NodeType* N) {
464 static inline nodes_iterator nodes_end(NodeType* N) {
469 template<> struct GraphTraits<const clang::ento::ExplodedNode*> {
470 typedef const clang::ento::ExplodedNode NodeType;
471 typedef NodeType::const_succ_iterator ChildIteratorType;
472 typedef llvm::df_iterator<NodeType*> nodes_iterator;
474 static inline NodeType* getEntryNode(NodeType* N) {
478 static inline ChildIteratorType child_begin(NodeType* N) {
479 return N->succ_begin();
482 static inline ChildIteratorType child_end(NodeType* N) {
483 return N->succ_end();
486 static inline nodes_iterator nodes_begin(NodeType* N) {
490 static inline nodes_iterator nodes_end(NodeType* N) {
495 } // end llvm namespace