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);
133 /// getLocation - Returns the edge associated with the given node.
134 ProgramPoint getLocation() const { return Location; }
136 const LocationContext *getLocationContext() const {
137 return getLocation().getLocationContext();
140 const StackFrameContext *getStackFrame() const {
141 return getLocationContext()->getCurrentStackFrame();
144 const Decl &getCodeDecl() const { return *getLocationContext()->getDecl(); }
146 CFG &getCFG() const { return *getLocationContext()->getCFG(); }
148 ParentMap &getParentMap() const {return getLocationContext()->getParentMap();}
150 template <typename T>
151 T &getAnalysis() const {
152 return *getLocationContext()->getAnalysis<T>();
155 const ProgramStateRef &getState() const { return State; }
157 template <typename T>
158 Optional<T> getLocationAs() const LLVM_LVALUE_FUNCTION {
159 return Location.getAs<T>();
162 static void Profile(llvm::FoldingSetNodeID &ID,
163 const ProgramPoint &Loc,
164 const ProgramStateRef &state,
167 ID.AddPointer(state.get());
168 ID.AddBoolean(IsSink);
171 void Profile(llvm::FoldingSetNodeID& ID) const {
172 // We avoid copy constructors by not using accessors.
173 Profile(ID, Location, State, isSink());
176 /// addPredeccessor - Adds a predecessor to the current node, and
177 /// in tandem add this node as a successor of the other node.
178 void addPredecessor(ExplodedNode *V, ExplodedGraph &G);
180 unsigned succ_size() const { return Succs.size(); }
181 unsigned pred_size() const { return Preds.size(); }
182 bool succ_empty() const { return Succs.empty(); }
183 bool pred_empty() const { return Preds.empty(); }
185 bool isSink() const { return Succs.getFlag(); }
187 bool hasSinglePred() const {
188 return (pred_size() == 1);
191 ExplodedNode *getFirstPred() {
192 return pred_empty() ? nullptr : *(pred_begin());
195 const ExplodedNode *getFirstPred() const {
196 return const_cast<ExplodedNode*>(this)->getFirstPred();
199 const ExplodedNode *getFirstSucc() const {
200 return succ_empty() ? nullptr : *(succ_begin());
203 // Iterators over successor and predecessor vertices.
204 typedef ExplodedNode* const * succ_iterator;
205 typedef const ExplodedNode* const * const_succ_iterator;
206 typedef ExplodedNode* const * pred_iterator;
207 typedef const ExplodedNode* const * const_pred_iterator;
209 pred_iterator pred_begin() { return Preds.begin(); }
210 pred_iterator pred_end() { return Preds.end(); }
212 const_pred_iterator pred_begin() const {
213 return const_cast<ExplodedNode*>(this)->pred_begin();
215 const_pred_iterator pred_end() const {
216 return const_cast<ExplodedNode*>(this)->pred_end();
219 succ_iterator succ_begin() { return Succs.begin(); }
220 succ_iterator succ_end() { return Succs.end(); }
222 const_succ_iterator succ_begin() const {
223 return const_cast<ExplodedNode*>(this)->succ_begin();
225 const_succ_iterator succ_end() const {
226 return const_cast<ExplodedNode*>(this)->succ_end();
236 virtual void AddEdge(ExplodedNode *Src, ExplodedNode *Dst) = 0;
239 static void SetAuditor(Auditor* A);
242 void replaceSuccessor(ExplodedNode *node) { Succs.replaceNode(node); }
243 void replacePredecessor(ExplodedNode *node) { Preds.replaceNode(node); }
246 typedef llvm::DenseMap<const ExplodedNode *, const ExplodedNode *>
247 InterExplodedGraphMap;
249 class ExplodedGraph {
251 friend class CoreEngine;
254 typedef std::vector<ExplodedNode *> NodeVector;
256 /// The roots of the simulation graph. Usually there will be only
257 /// one, but clients are free to establish multiple subgraphs within a single
258 /// SimulGraph. Moreover, these subgraphs can often merge when paths from
259 /// different roots reach the same state at the same program location.
262 /// The nodes in the simulation graph which have been
263 /// specially marked as the endpoint of an abstract simulation path.
266 /// Nodes - The nodes in the graph.
267 llvm::FoldingSet<ExplodedNode> Nodes;
269 /// BVC - Allocator and context for allocating nodes and their predecessor
270 /// and successor groups.
271 BumpVectorContext BVC;
273 /// NumNodes - The number of nodes in the graph.
276 /// A list of recently allocated nodes that can potentially be recycled.
277 NodeVector ChangedNodes;
279 /// A list of nodes that can be reused.
280 NodeVector FreeNodes;
282 /// Determines how often nodes are reclaimed.
284 /// If this is 0, nodes will never be reclaimed.
285 unsigned ReclaimNodeInterval;
287 /// Counter to determine when to reclaim nodes.
288 unsigned ReclaimCounter;
292 /// \brief Retrieve the node associated with a (Location,State) pair,
293 /// where the 'Location' is a ProgramPoint in the CFG. If no node for
294 /// this pair exists, it is created. IsNew is set to true if
295 /// the node was freshly created.
296 ExplodedNode *getNode(const ProgramPoint &L, ProgramStateRef State,
298 bool* IsNew = nullptr);
300 std::unique_ptr<ExplodedGraph> MakeEmptyGraph() const {
301 return llvm::make_unique<ExplodedGraph>();
304 /// addRoot - Add an untyped node to the set of roots.
305 ExplodedNode *addRoot(ExplodedNode *V) {
310 /// addEndOfPath - Add an untyped node to the set of EOP nodes.
311 ExplodedNode *addEndOfPath(ExplodedNode *V) {
312 EndNodes.push_back(V);
320 unsigned num_roots() const { return Roots.size(); }
321 unsigned num_eops() const { return EndNodes.size(); }
323 bool empty() const { return NumNodes == 0; }
324 unsigned size() const { return NumNodes; }
327 typedef ExplodedNode NodeTy;
328 typedef llvm::FoldingSet<ExplodedNode> AllNodesTy;
329 typedef NodeVector::iterator roots_iterator;
330 typedef NodeVector::const_iterator const_roots_iterator;
331 typedef NodeVector::iterator eop_iterator;
332 typedef NodeVector::const_iterator const_eop_iterator;
333 typedef AllNodesTy::iterator node_iterator;
334 typedef AllNodesTy::const_iterator const_node_iterator;
336 node_iterator nodes_begin() { return Nodes.begin(); }
338 node_iterator nodes_end() { return Nodes.end(); }
340 const_node_iterator nodes_begin() const { return Nodes.begin(); }
342 const_node_iterator nodes_end() const { return Nodes.end(); }
344 roots_iterator roots_begin() { return Roots.begin(); }
346 roots_iterator roots_end() { return Roots.end(); }
348 const_roots_iterator roots_begin() const { return Roots.begin(); }
350 const_roots_iterator roots_end() const { return Roots.end(); }
352 eop_iterator eop_begin() { return EndNodes.begin(); }
354 eop_iterator eop_end() { return EndNodes.end(); }
356 const_eop_iterator eop_begin() const { return EndNodes.begin(); }
358 const_eop_iterator eop_end() const { return EndNodes.end(); }
360 llvm::BumpPtrAllocator & getAllocator() { return BVC.getAllocator(); }
361 BumpVectorContext &getNodeAllocator() { return BVC; }
363 typedef llvm::DenseMap<const ExplodedNode*, ExplodedNode*> NodeMap;
365 /// Creates a trimmed version of the graph that only contains paths leading
366 /// to the given nodes.
368 /// \param Nodes The nodes which must appear in the final graph. Presumably
369 /// these are end-of-path nodes (i.e. they have no successors).
370 /// \param[out] ForwardMap A optional map from nodes in this graph to nodes in
371 /// the returned graph.
372 /// \param[out] InverseMap An optional map from nodes in the returned graph to
373 /// nodes in this graph.
374 /// \returns The trimmed graph
375 std::unique_ptr<ExplodedGraph>
376 trim(ArrayRef<const NodeTy *> Nodes,
377 InterExplodedGraphMap *ForwardMap = nullptr,
378 InterExplodedGraphMap *InverseMap = nullptr) const;
380 /// Enable tracking of recently allocated nodes for potential reclamation
381 /// when calling reclaimRecentlyAllocatedNodes().
382 void enableNodeReclamation(unsigned Interval) {
383 ReclaimCounter = ReclaimNodeInterval = Interval;
386 /// Reclaim "uninteresting" nodes created since the last time this method
388 void reclaimRecentlyAllocatedNodes();
390 /// \brief Returns true if nodes for the given expression kind are always
392 static bool isInterestingLValueExpr(const Expr *Ex);
395 bool shouldCollect(const ExplodedNode *node);
396 void collectNode(ExplodedNode *node);
399 class ExplodedNodeSet {
400 typedef llvm::SmallPtrSet<ExplodedNode*,5> ImplTy;
404 ExplodedNodeSet(ExplodedNode *N) {
405 assert (N && !static_cast<ExplodedNode*>(N)->isSink());
411 inline void Add(ExplodedNode *N) {
412 if (N && !static_cast<ExplodedNode*>(N)->isSink()) Impl.insert(N);
415 typedef ImplTy::iterator iterator;
416 typedef ImplTy::const_iterator const_iterator;
418 unsigned size() const { return Impl.size(); }
419 bool empty() const { return Impl.empty(); }
420 bool erase(ExplodedNode *N) { return Impl.erase(N); }
422 void clear() { Impl.clear(); }
423 void insert(const ExplodedNodeSet &S) {
428 Impl.insert(S.begin(), S.end());
431 inline iterator begin() { return Impl.begin(); }
432 inline iterator end() { return Impl.end(); }
434 inline const_iterator begin() const { return Impl.begin(); }
435 inline const_iterator end() const { return Impl.end(); }
438 } // end GR namespace
440 } // end clang namespace
445 template<> struct GraphTraits<clang::ento::ExplodedNode*> {
446 typedef clang::ento::ExplodedNode NodeType;
447 typedef NodeType::succ_iterator ChildIteratorType;
448 typedef llvm::df_iterator<NodeType*> nodes_iterator;
450 static inline NodeType* getEntryNode(NodeType* N) {
454 static inline ChildIteratorType child_begin(NodeType* N) {
455 return N->succ_begin();
458 static inline ChildIteratorType child_end(NodeType* N) {
459 return N->succ_end();
462 static inline nodes_iterator nodes_begin(NodeType* N) {
466 static inline nodes_iterator nodes_end(NodeType* N) {
471 template<> struct GraphTraits<const clang::ento::ExplodedNode*> {
472 typedef const clang::ento::ExplodedNode NodeType;
473 typedef NodeType::const_succ_iterator ChildIteratorType;
474 typedef llvm::df_iterator<NodeType*> nodes_iterator;
476 static inline NodeType* getEntryNode(NodeType* N) {
480 static inline ChildIteratorType child_begin(NodeType* N) {
481 return N->succ_begin();
484 static inline ChildIteratorType child_end(NodeType* N) {
485 return N->succ_end();
488 static inline nodes_iterator nodes_begin(NodeType* N) {
492 static inline nodes_iterator nodes_end(NodeType* N) {
497 } // end llvm namespace