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"
46 //===----------------------------------------------------------------------===//
47 // ExplodedGraph "implementation" classes. These classes are not typed to
48 // contain a specific kind of state. Typed-specialized versions are defined
49 // on top of these classes.
50 //===----------------------------------------------------------------------===//
52 // ExplodedNode is not constified all over the engine because we need to add
53 // successors to it at any time after creating it.
55 class ExplodedNode : public llvm::FoldingSetNode {
56 friend class ExplodedGraph;
57 friend class CoreEngine;
58 friend class NodeBuilder;
59 friend class BranchNodeBuilder;
60 friend class IndirectGotoNodeBuilder;
61 friend class SwitchNodeBuilder;
62 friend class EndOfFunctionNodeBuilder;
64 /// Efficiently stores a list of ExplodedNodes, or an optional flag.
66 /// NodeGroup provides opaque storage for a list of ExplodedNodes, optimizing
67 /// for the case when there is only one node in the group. This is a fairly
68 /// common case in an ExplodedGraph, where most nodes have only one
69 /// predecessor and many have only one successor. It can also be used to
70 /// store a flag rather than a node list, which ExplodedNode uses to mark
71 /// whether a node is a sink. If the flag is set, the group is implicitly
72 /// empty and no nodes may be added.
74 // Conceptually a discriminated union. If the low bit is set, the node is
75 // a sink. If the low bit is not set, the pointer refers to the storage
76 // for the nodes in the group.
77 // This is not a PointerIntPair in order to keep the storage type opaque.
81 NodeGroup(bool Flag = false) : P(Flag) {
82 assert(getFlag() == Flag);
85 ExplodedNode * const *begin() const;
87 ExplodedNode * const *end() const;
89 unsigned size() const;
91 bool empty() const { return P == 0 || getFlag() != 0; }
93 /// Adds a node to the list.
95 /// The group must not have been created with its flag set.
96 void addNode(ExplodedNode *N, ExplodedGraph &G);
98 /// Replaces the single node in this group with a new node.
100 /// Note that this should only be used when you know the group was not
101 /// created with its flag set, and that the group is empty or contains
102 /// only a single node.
103 void replaceNode(ExplodedNode *node);
105 /// Returns whether this group was created with its flag set.
106 bool getFlag() const {
111 /// Location - The program location (within a function body) associated
113 const ProgramPoint Location;
115 /// State - The state associated with this node.
116 ProgramStateRef State;
118 /// Preds - The predecessors of this node.
121 /// Succs - The successors of this node.
125 explicit ExplodedNode(const ProgramPoint &loc, ProgramStateRef state,
127 : Location(loc), State(std::move(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 /// \brief Create a node for a (Location, State) pair,
299 /// but don't store it for deduplication later. This
300 /// is useful when copying an already completed
301 /// ExplodedGraph for further processing.
302 ExplodedNode *createUncachedNode(const ProgramPoint &L,
303 ProgramStateRef State,
304 bool IsSink = false);
306 std::unique_ptr<ExplodedGraph> MakeEmptyGraph() const {
307 return llvm::make_unique<ExplodedGraph>();
310 /// addRoot - Add an untyped node to the set of roots.
311 ExplodedNode *addRoot(ExplodedNode *V) {
316 /// addEndOfPath - Add an untyped node to the set of EOP nodes.
317 ExplodedNode *addEndOfPath(ExplodedNode *V) {
318 EndNodes.push_back(V);
326 unsigned num_roots() const { return Roots.size(); }
327 unsigned num_eops() const { return EndNodes.size(); }
329 bool empty() const { return NumNodes == 0; }
330 unsigned size() const { return NumNodes; }
332 void reserve(unsigned NodeCount) { Nodes.reserve(NodeCount); }
335 typedef ExplodedNode NodeTy;
336 typedef llvm::FoldingSet<ExplodedNode> AllNodesTy;
337 typedef NodeVector::iterator roots_iterator;
338 typedef NodeVector::const_iterator const_roots_iterator;
339 typedef NodeVector::iterator eop_iterator;
340 typedef NodeVector::const_iterator const_eop_iterator;
341 typedef AllNodesTy::iterator node_iterator;
342 typedef AllNodesTy::const_iterator const_node_iterator;
344 node_iterator nodes_begin() { return Nodes.begin(); }
346 node_iterator nodes_end() { return Nodes.end(); }
348 const_node_iterator nodes_begin() const { return Nodes.begin(); }
350 const_node_iterator nodes_end() const { return Nodes.end(); }
352 roots_iterator roots_begin() { return Roots.begin(); }
354 roots_iterator roots_end() { return Roots.end(); }
356 const_roots_iterator roots_begin() const { return Roots.begin(); }
358 const_roots_iterator roots_end() const { return Roots.end(); }
360 eop_iterator eop_begin() { return EndNodes.begin(); }
362 eop_iterator eop_end() { return EndNodes.end(); }
364 const_eop_iterator eop_begin() const { return EndNodes.begin(); }
366 const_eop_iterator eop_end() const { return EndNodes.end(); }
368 llvm::BumpPtrAllocator & getAllocator() { return BVC.getAllocator(); }
369 BumpVectorContext &getNodeAllocator() { return BVC; }
371 typedef llvm::DenseMap<const ExplodedNode*, ExplodedNode*> NodeMap;
373 /// Creates a trimmed version of the graph that only contains paths leading
374 /// to the given nodes.
376 /// \param Nodes The nodes which must appear in the final graph. Presumably
377 /// these are end-of-path nodes (i.e. they have no successors).
378 /// \param[out] ForwardMap A optional map from nodes in this graph to nodes in
379 /// the returned graph.
380 /// \param[out] InverseMap An optional map from nodes in the returned graph to
381 /// nodes in this graph.
382 /// \returns The trimmed graph
383 std::unique_ptr<ExplodedGraph>
384 trim(ArrayRef<const NodeTy *> Nodes,
385 InterExplodedGraphMap *ForwardMap = nullptr,
386 InterExplodedGraphMap *InverseMap = nullptr) const;
388 /// Enable tracking of recently allocated nodes for potential reclamation
389 /// when calling reclaimRecentlyAllocatedNodes().
390 void enableNodeReclamation(unsigned Interval) {
391 ReclaimCounter = ReclaimNodeInterval = Interval;
394 /// Reclaim "uninteresting" nodes created since the last time this method
396 void reclaimRecentlyAllocatedNodes();
398 /// \brief Returns true if nodes for the given expression kind are always
400 static bool isInterestingLValueExpr(const Expr *Ex);
403 bool shouldCollect(const ExplodedNode *node);
404 void collectNode(ExplodedNode *node);
407 class ExplodedNodeSet {
408 typedef llvm::SmallPtrSet<ExplodedNode*,5> ImplTy;
412 ExplodedNodeSet(ExplodedNode *N) {
413 assert (N && !static_cast<ExplodedNode*>(N)->isSink());
419 inline void Add(ExplodedNode *N) {
420 if (N && !static_cast<ExplodedNode*>(N)->isSink()) Impl.insert(N);
423 typedef ImplTy::iterator iterator;
424 typedef ImplTy::const_iterator const_iterator;
426 unsigned size() const { return Impl.size(); }
427 bool empty() const { return Impl.empty(); }
428 bool erase(ExplodedNode *N) { return Impl.erase(N); }
430 void clear() { Impl.clear(); }
431 void insert(const ExplodedNodeSet &S) {
436 Impl.insert(S.begin(), S.end());
439 inline iterator begin() { return Impl.begin(); }
440 inline iterator end() { return Impl.end(); }
442 inline const_iterator begin() const { return Impl.begin(); }
443 inline const_iterator end() const { return Impl.end(); }
446 } // end GR namespace
448 } // end clang namespace
453 template<> struct GraphTraits<clang::ento::ExplodedNode*> {
454 typedef clang::ento::ExplodedNode NodeType;
455 typedef NodeType::succ_iterator ChildIteratorType;
456 typedef llvm::df_iterator<NodeType*> nodes_iterator;
458 static inline NodeType* getEntryNode(NodeType* N) {
462 static inline ChildIteratorType child_begin(NodeType* N) {
463 return N->succ_begin();
466 static inline ChildIteratorType child_end(NodeType* N) {
467 return N->succ_end();
470 static inline nodes_iterator nodes_begin(NodeType* N) {
474 static inline nodes_iterator nodes_end(NodeType* N) {
479 template<> struct GraphTraits<const clang::ento::ExplodedNode*> {
480 typedef const clang::ento::ExplodedNode NodeType;
481 typedef NodeType::const_succ_iterator ChildIteratorType;
482 typedef llvm::df_iterator<NodeType*> nodes_iterator;
484 static inline NodeType* getEntryNode(NodeType* N) {
488 static inline ChildIteratorType child_begin(NodeType* N) {
489 return N->succ_begin();
492 static inline ChildIteratorType child_end(NodeType* N) {
493 return N->succ_end();
496 static inline nodes_iterator nodes_begin(NodeType* N) {
500 static inline nodes_iterator nodes_end(NodeType* N) {
505 } // end llvm namespace