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_GR_EXPLODEDGRAPH
20 #define LLVM_CLANG_GR_EXPLODEDGRAPH
22 #include "clang/Analysis/ProgramPoint.h"
23 #include "clang/Analysis/AnalysisContext.h"
24 #include "clang/AST/Decl.h"
25 #include "llvm/ADT/SmallVector.h"
26 #include "llvm/ADT/FoldingSet.h"
27 #include "llvm/ADT/SmallPtrSet.h"
28 #include "llvm/Support/Allocator.h"
29 #include "llvm/ADT/OwningPtr.h"
30 #include "llvm/ADT/GraphTraits.h"
31 #include "llvm/ADT/DepthFirstIterator.h"
32 #include "llvm/Support/Casting.h"
33 #include "clang/Analysis/Support/BumpVector.h"
34 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.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 ProgramStateRef getState() const { return State; }
157 template <typename T>
158 const T* getLocationAs() const { return llvm::dyn_cast<T>(&Location); }
160 static void Profile(llvm::FoldingSetNodeID &ID,
161 const ProgramPoint &Loc,
162 const ProgramStateRef &state,
165 ID.AddPointer(state.getPtr());
166 ID.AddBoolean(IsSink);
169 void Profile(llvm::FoldingSetNodeID& ID) const {
170 Profile(ID, getLocation(), getState(), 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() ? NULL : *(pred_begin());
192 const ExplodedNode *getFirstPred() const {
193 return const_cast<ExplodedNode*>(this)->getFirstPred();
196 // Iterators over successor and predecessor vertices.
197 typedef ExplodedNode* const * succ_iterator;
198 typedef const ExplodedNode* const * const_succ_iterator;
199 typedef ExplodedNode* const * pred_iterator;
200 typedef const ExplodedNode* const * const_pred_iterator;
202 pred_iterator pred_begin() { return Preds.begin(); }
203 pred_iterator pred_end() { return Preds.end(); }
205 const_pred_iterator pred_begin() const {
206 return const_cast<ExplodedNode*>(this)->pred_begin();
208 const_pred_iterator pred_end() const {
209 return const_cast<ExplodedNode*>(this)->pred_end();
212 succ_iterator succ_begin() { return Succs.begin(); }
213 succ_iterator succ_end() { return Succs.end(); }
215 const_succ_iterator succ_begin() const {
216 return const_cast<ExplodedNode*>(this)->succ_begin();
218 const_succ_iterator succ_end() const {
219 return const_cast<ExplodedNode*>(this)->succ_end();
229 virtual void AddEdge(ExplodedNode *Src, ExplodedNode *Dst) = 0;
232 static void SetAuditor(Auditor* A);
235 void replaceSuccessor(ExplodedNode *node) { Succs.replaceNode(node); }
236 void replacePredecessor(ExplodedNode *node) { Preds.replaceNode(node); }
239 // FIXME: Is this class necessary?
240 class InterExplodedGraphMap {
241 virtual void anchor();
242 llvm::DenseMap<const ExplodedNode*, ExplodedNode*> M;
243 friend class ExplodedGraph;
246 ExplodedNode *getMappedNode(const ExplodedNode *N) const;
248 InterExplodedGraphMap() {}
249 virtual ~InterExplodedGraphMap() {}
252 class ExplodedGraph {
254 friend class CoreEngine;
257 typedef std::vector<ExplodedNode *> NodeVector;
259 /// The roots of the simulation graph. Usually there will be only
260 /// one, but clients are free to establish multiple subgraphs within a single
261 /// SimulGraph. Moreover, these subgraphs can often merge when paths from
262 /// different roots reach the same state at the same program location.
265 /// The nodes in the simulation graph which have been
266 /// specially marked as the endpoint of an abstract simulation path.
269 /// Nodes - The nodes in the graph.
270 llvm::FoldingSet<ExplodedNode> Nodes;
272 /// BVC - Allocator and context for allocating nodes and their predecessor
273 /// and successor groups.
274 BumpVectorContext BVC;
276 /// NumNodes - The number of nodes in the graph.
279 /// A list of recently allocated nodes that can potentially be recycled.
280 NodeVector ChangedNodes;
282 /// A list of nodes that can be reused.
283 NodeVector FreeNodes;
285 /// Determines how often nodes are reclaimed.
287 /// If this is 0, nodes will never be reclaimed.
288 unsigned ReclaimNodeInterval;
290 /// Counter to determine when to reclaim nodes.
291 unsigned ReclaimCounter;
295 /// \brief Retrieve the node associated with a (Location,State) pair,
296 /// where the 'Location' is a ProgramPoint in the CFG. If no node for
297 /// this pair exists, it is created. IsNew is set to true if
298 /// the node was freshly created.
299 ExplodedNode *getNode(const ProgramPoint &L, ProgramStateRef State,
303 ExplodedGraph* MakeEmptyGraph() const {
304 return new ExplodedGraph();
307 /// addRoot - Add an untyped node to the set of roots.
308 ExplodedNode *addRoot(ExplodedNode *V) {
313 /// addEndOfPath - Add an untyped node to the set of EOP nodes.
314 ExplodedNode *addEndOfPath(ExplodedNode *V) {
315 EndNodes.push_back(V);
323 unsigned num_roots() const { return Roots.size(); }
324 unsigned num_eops() const { return EndNodes.size(); }
326 bool empty() const { return NumNodes == 0; }
327 unsigned size() const { return NumNodes; }
330 typedef ExplodedNode NodeTy;
331 typedef llvm::FoldingSet<ExplodedNode> AllNodesTy;
332 typedef NodeVector::iterator roots_iterator;
333 typedef NodeVector::const_iterator const_roots_iterator;
334 typedef NodeVector::iterator eop_iterator;
335 typedef NodeVector::const_iterator const_eop_iterator;
336 typedef AllNodesTy::iterator node_iterator;
337 typedef AllNodesTy::const_iterator const_node_iterator;
339 node_iterator nodes_begin() { return Nodes.begin(); }
341 node_iterator nodes_end() { return Nodes.end(); }
343 const_node_iterator nodes_begin() const { return Nodes.begin(); }
345 const_node_iterator nodes_end() const { return Nodes.end(); }
347 roots_iterator roots_begin() { return Roots.begin(); }
349 roots_iterator roots_end() { return Roots.end(); }
351 const_roots_iterator roots_begin() const { return Roots.begin(); }
353 const_roots_iterator roots_end() const { return Roots.end(); }
355 eop_iterator eop_begin() { return EndNodes.begin(); }
357 eop_iterator eop_end() { return EndNodes.end(); }
359 const_eop_iterator eop_begin() const { return EndNodes.begin(); }
361 const_eop_iterator eop_end() const { return EndNodes.end(); }
363 llvm::BumpPtrAllocator & getAllocator() { return BVC.getAllocator(); }
364 BumpVectorContext &getNodeAllocator() { return BVC; }
366 typedef llvm::DenseMap<const ExplodedNode*, ExplodedNode*> NodeMap;
368 std::pair<ExplodedGraph*, InterExplodedGraphMap*>
369 Trim(const NodeTy* const* NBeg, const NodeTy* const* NEnd,
370 llvm::DenseMap<const void*, const void*> *InverseMap = 0) const;
372 ExplodedGraph* TrimInternal(const ExplodedNode* const * NBeg,
373 const ExplodedNode* const * NEnd,
374 InterExplodedGraphMap *M,
375 llvm::DenseMap<const void*, const void*> *InverseMap) const;
377 /// Enable tracking of recently allocated nodes for potential reclamation
378 /// when calling reclaimRecentlyAllocatedNodes().
379 void enableNodeReclamation(unsigned Interval) {
380 ReclaimCounter = ReclaimNodeInterval = Interval;
383 /// Reclaim "uninteresting" nodes created since the last time this method
385 void reclaimRecentlyAllocatedNodes();
388 bool shouldCollect(const ExplodedNode *node);
389 void collectNode(ExplodedNode *node);
392 class ExplodedNodeSet {
393 typedef llvm::SmallPtrSet<ExplodedNode*,5> ImplTy;
397 ExplodedNodeSet(ExplodedNode *N) {
398 assert (N && !static_cast<ExplodedNode*>(N)->isSink());
404 inline void Add(ExplodedNode *N) {
405 if (N && !static_cast<ExplodedNode*>(N)->isSink()) Impl.insert(N);
408 typedef ImplTy::iterator iterator;
409 typedef ImplTy::const_iterator const_iterator;
411 unsigned size() const { return Impl.size(); }
412 bool empty() const { return Impl.empty(); }
413 bool erase(ExplodedNode *N) { return Impl.erase(N); }
415 void clear() { Impl.clear(); }
416 void insert(const ExplodedNodeSet &S) {
421 Impl.insert(S.begin(), S.end());
424 inline iterator begin() { return Impl.begin(); }
425 inline iterator end() { return Impl.end(); }
427 inline const_iterator begin() const { return Impl.begin(); }
428 inline const_iterator end() const { return Impl.end(); }
431 } // end GR namespace
433 } // end clang namespace
438 template<> struct GraphTraits<clang::ento::ExplodedNode*> {
439 typedef clang::ento::ExplodedNode NodeType;
440 typedef NodeType::succ_iterator ChildIteratorType;
441 typedef llvm::df_iterator<NodeType*> nodes_iterator;
443 static inline NodeType* getEntryNode(NodeType* N) {
447 static inline ChildIteratorType child_begin(NodeType* N) {
448 return N->succ_begin();
451 static inline ChildIteratorType child_end(NodeType* N) {
452 return N->succ_end();
455 static inline nodes_iterator nodes_begin(NodeType* N) {
459 static inline nodes_iterator nodes_end(NodeType* N) {
464 template<> struct GraphTraits<const clang::ento::ExplodedNode*> {
465 typedef const clang::ento::ExplodedNode NodeType;
466 typedef NodeType::const_succ_iterator ChildIteratorType;
467 typedef llvm::df_iterator<NodeType*> nodes_iterator;
469 static inline NodeType* getEntryNode(NodeType* N) {
473 static inline ChildIteratorType child_begin(NodeType* N) {
474 return N->succ_begin();
477 static inline ChildIteratorType child_end(NodeType* N) {
478 return N->succ_end();
481 static inline nodes_iterator nodes_begin(NodeType* N) {
485 static inline nodes_iterator nodes_end(NodeType* N) {
490 } // end llvm namespace