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/AnalysisDeclContext.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/SetVector.h"
31 #include "llvm/Support/Allocator.h"
32 #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.
124 explicit ExplodedNode(const ProgramPoint &loc, ProgramStateRef state,
126 : Location(loc), State(std::move(state)), Succs(IsSink) {
127 assert(isSink() == IsSink);
130 /// getLocation - Returns the edge associated with the given node.
131 ProgramPoint getLocation() const { return Location; }
133 const LocationContext *getLocationContext() const {
134 return getLocation().getLocationContext();
137 const StackFrameContext *getStackFrame() const {
138 return getLocationContext()->getCurrentStackFrame();
141 const Decl &getCodeDecl() const { return *getLocationContext()->getDecl(); }
143 CFG &getCFG() const { return *getLocationContext()->getCFG(); }
145 ParentMap &getParentMap() const {return getLocationContext()->getParentMap();}
147 template <typename T>
148 T &getAnalysis() const {
149 return *getLocationContext()->getAnalysis<T>();
152 const ProgramStateRef &getState() const { return State; }
154 template <typename T>
155 Optional<T> getLocationAs() const LLVM_LVALUE_FUNCTION {
156 return Location.getAs<T>();
159 static void Profile(llvm::FoldingSetNodeID &ID,
160 const ProgramPoint &Loc,
161 const ProgramStateRef &state,
164 ID.AddPointer(state.get());
165 ID.AddBoolean(IsSink);
168 void Profile(llvm::FoldingSetNodeID& ID) const {
169 // We avoid copy constructors by not using accessors.
170 Profile(ID, Location, State, isSink());
173 /// addPredeccessor - Adds a predecessor to the current node, and
174 /// in tandem add this node as a successor of the other node.
175 void addPredecessor(ExplodedNode *V, ExplodedGraph &G);
177 unsigned succ_size() const { return Succs.size(); }
178 unsigned pred_size() const { return Preds.size(); }
179 bool succ_empty() const { return Succs.empty(); }
180 bool pred_empty() const { return Preds.empty(); }
182 bool isSink() const { return Succs.getFlag(); }
184 bool hasSinglePred() const {
185 return (pred_size() == 1);
188 ExplodedNode *getFirstPred() {
189 return pred_empty() ? nullptr : *(pred_begin());
192 const ExplodedNode *getFirstPred() const {
193 return const_cast<ExplodedNode*>(this)->getFirstPred();
196 const ExplodedNode *getFirstSucc() const {
197 return succ_empty() ? nullptr : *(succ_begin());
200 // Iterators over successor and predecessor vertices.
201 typedef ExplodedNode* const * succ_iterator;
202 typedef const ExplodedNode* const * const_succ_iterator;
203 typedef ExplodedNode* const * pred_iterator;
204 typedef const ExplodedNode* const * const_pred_iterator;
206 pred_iterator pred_begin() { return Preds.begin(); }
207 pred_iterator pred_end() { return Preds.end(); }
209 const_pred_iterator pred_begin() const {
210 return const_cast<ExplodedNode*>(this)->pred_begin();
212 const_pred_iterator pred_end() const {
213 return const_cast<ExplodedNode*>(this)->pred_end();
216 succ_iterator succ_begin() { return Succs.begin(); }
217 succ_iterator succ_end() { return Succs.end(); }
219 const_succ_iterator succ_begin() const {
220 return const_cast<ExplodedNode*>(this)->succ_begin();
222 const_succ_iterator succ_end() const {
223 return const_cast<ExplodedNode*>(this)->succ_end();
233 virtual void AddEdge(ExplodedNode *Src, ExplodedNode *Dst) = 0;
236 static void SetAuditor(Auditor* A);
239 void replaceSuccessor(ExplodedNode *node) { Succs.replaceNode(node); }
240 void replacePredecessor(ExplodedNode *node) { Preds.replaceNode(node); }
243 typedef llvm::DenseMap<const ExplodedNode *, const ExplodedNode *>
244 InterExplodedGraphMap;
246 class ExplodedGraph {
248 friend class CoreEngine;
251 typedef std::vector<ExplodedNode *> NodeVector;
253 /// The roots of the simulation graph. Usually there will be only
254 /// one, but clients are free to establish multiple subgraphs within a single
255 /// SimulGraph. Moreover, these subgraphs can often merge when paths from
256 /// different roots reach the same state at the same program location.
259 /// The nodes in the simulation graph which have been
260 /// specially marked as the endpoint of an abstract simulation path.
263 /// Nodes - The nodes in the graph.
264 llvm::FoldingSet<ExplodedNode> Nodes;
266 /// BVC - Allocator and context for allocating nodes and their predecessor
267 /// and successor groups.
268 BumpVectorContext BVC;
270 /// NumNodes - The number of nodes in the graph.
273 /// A list of recently allocated nodes that can potentially be recycled.
274 NodeVector ChangedNodes;
276 /// A list of nodes that can be reused.
277 NodeVector FreeNodes;
279 /// Determines how often nodes are reclaimed.
281 /// If this is 0, nodes will never be reclaimed.
282 unsigned ReclaimNodeInterval;
284 /// Counter to determine when to reclaim nodes.
285 unsigned ReclaimCounter;
289 /// \brief Retrieve the node associated with a (Location,State) pair,
290 /// where the 'Location' is a ProgramPoint in the CFG. If no node for
291 /// this pair exists, it is created. IsNew is set to true if
292 /// the node was freshly created.
293 ExplodedNode *getNode(const ProgramPoint &L, ProgramStateRef State,
295 bool* IsNew = nullptr);
297 /// \brief Create a node for a (Location, State) pair,
298 /// but don't store it for deduplication later. This
299 /// is useful when copying an already completed
300 /// ExplodedGraph for further processing.
301 ExplodedNode *createUncachedNode(const ProgramPoint &L,
302 ProgramStateRef State,
303 bool IsSink = false);
305 std::unique_ptr<ExplodedGraph> MakeEmptyGraph() const {
306 return llvm::make_unique<ExplodedGraph>();
309 /// addRoot - Add an untyped node to the set of roots.
310 ExplodedNode *addRoot(ExplodedNode *V) {
315 /// addEndOfPath - Add an untyped node to the set of EOP nodes.
316 ExplodedNode *addEndOfPath(ExplodedNode *V) {
317 EndNodes.push_back(V);
325 unsigned num_roots() const { return Roots.size(); }
326 unsigned num_eops() const { return EndNodes.size(); }
328 bool empty() const { return NumNodes == 0; }
329 unsigned size() const { return NumNodes; }
331 void reserve(unsigned NodeCount) { Nodes.reserve(NodeCount); }
334 typedef ExplodedNode NodeTy;
335 typedef llvm::FoldingSet<ExplodedNode> AllNodesTy;
336 typedef NodeVector::iterator roots_iterator;
337 typedef NodeVector::const_iterator const_roots_iterator;
338 typedef NodeVector::iterator eop_iterator;
339 typedef NodeVector::const_iterator const_eop_iterator;
340 typedef AllNodesTy::iterator node_iterator;
341 typedef AllNodesTy::const_iterator const_node_iterator;
343 node_iterator nodes_begin() { return Nodes.begin(); }
345 node_iterator nodes_end() { return Nodes.end(); }
347 const_node_iterator nodes_begin() const { return Nodes.begin(); }
349 const_node_iterator nodes_end() const { return Nodes.end(); }
351 roots_iterator roots_begin() { return Roots.begin(); }
353 roots_iterator roots_end() { return Roots.end(); }
355 const_roots_iterator roots_begin() const { return Roots.begin(); }
357 const_roots_iterator roots_end() const { return Roots.end(); }
359 eop_iterator eop_begin() { return EndNodes.begin(); }
361 eop_iterator eop_end() { return EndNodes.end(); }
363 const_eop_iterator eop_begin() const { return EndNodes.begin(); }
365 const_eop_iterator eop_end() const { return EndNodes.end(); }
367 llvm::BumpPtrAllocator & getAllocator() { return BVC.getAllocator(); }
368 BumpVectorContext &getNodeAllocator() { return BVC; }
370 typedef llvm::DenseMap<const ExplodedNode*, ExplodedNode*> NodeMap;
372 /// Creates a trimmed version of the graph that only contains paths leading
373 /// to the given nodes.
375 /// \param Nodes The nodes which must appear in the final graph. Presumably
376 /// these are end-of-path nodes (i.e. they have no successors).
377 /// \param[out] ForwardMap A optional map from nodes in this graph to nodes in
378 /// the returned graph.
379 /// \param[out] InverseMap An optional map from nodes in the returned graph to
380 /// nodes in this graph.
381 /// \returns The trimmed graph
382 std::unique_ptr<ExplodedGraph>
383 trim(ArrayRef<const NodeTy *> Nodes,
384 InterExplodedGraphMap *ForwardMap = nullptr,
385 InterExplodedGraphMap *InverseMap = nullptr) const;
387 /// Enable tracking of recently allocated nodes for potential reclamation
388 /// when calling reclaimRecentlyAllocatedNodes().
389 void enableNodeReclamation(unsigned Interval) {
390 ReclaimCounter = ReclaimNodeInterval = Interval;
393 /// Reclaim "uninteresting" nodes created since the last time this method
395 void reclaimRecentlyAllocatedNodes();
397 /// \brief Returns true if nodes for the given expression kind are always
399 static bool isInterestingLValueExpr(const Expr *Ex);
402 bool shouldCollect(const ExplodedNode *node);
403 void collectNode(ExplodedNode *node);
406 class ExplodedNodeSet {
407 typedef llvm::SmallSetVector<ExplodedNode*, 4> ImplTy;
411 ExplodedNodeSet(ExplodedNode *N) {
412 assert (N && !static_cast<ExplodedNode*>(N)->isSink());
418 inline void Add(ExplodedNode *N) {
419 if (N && !static_cast<ExplodedNode*>(N)->isSink()) Impl.insert(N);
422 typedef ImplTy::iterator iterator;
423 typedef ImplTy::const_iterator const_iterator;
425 unsigned size() const { return Impl.size(); }
426 bool empty() const { return Impl.empty(); }
427 bool erase(ExplodedNode *N) { return Impl.remove(N); }
429 void clear() { Impl.clear(); }
430 void insert(const ExplodedNodeSet &S) {
435 Impl.insert(S.begin(), S.end());
438 inline iterator begin() { return Impl.begin(); }
439 inline iterator end() { return Impl.end(); }
441 inline const_iterator begin() const { return Impl.begin(); }
442 inline const_iterator end() const { return Impl.end(); }
445 } // end GR namespace
447 } // end clang namespace
452 template<> struct GraphTraits<clang::ento::ExplodedNode*> {
453 typedef clang::ento::ExplodedNode *NodeRef;
454 typedef clang::ento::ExplodedNode::succ_iterator ChildIteratorType;
455 typedef llvm::df_iterator<NodeRef> nodes_iterator;
457 static NodeRef getEntryNode(NodeRef N) { return N; }
459 static ChildIteratorType child_begin(NodeRef N) { return N->succ_begin(); }
461 static ChildIteratorType child_end(NodeRef N) { return N->succ_end(); }
463 static nodes_iterator nodes_begin(NodeRef N) { return df_begin(N); }
465 static nodes_iterator nodes_end(NodeRef N) { return df_end(N); }
468 template<> struct GraphTraits<const clang::ento::ExplodedNode*> {
469 typedef const clang::ento::ExplodedNode *NodeRef;
470 typedef clang::ento::ExplodedNode::const_succ_iterator ChildIteratorType;
471 typedef llvm::df_iterator<NodeRef> nodes_iterator;
473 static NodeRef getEntryNode(NodeRef N) { return N; }
475 static ChildIteratorType child_begin(NodeRef N) { return N->succ_begin(); }
477 static ChildIteratorType child_end(NodeRef N) { return N->succ_end(); }
479 static nodes_iterator nodes_begin(NodeRef N) { return df_begin(N); }
481 static nodes_iterator nodes_end(NodeRef N) { return df_end(N); }
484 } // end llvm namespace