1 //==- CoreEngine.h - Path-Sensitive Dataflow Engine ----------------*- 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 a generic engine for intraprocedural, path-sensitive,
11 // dataflow analysis via graph reachability.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CLANG_GR_COREENGINE
16 #define LLVM_CLANG_GR_COREENGINE
18 #include "clang/AST/Expr.h"
19 #include "clang/Analysis/AnalysisContext.h"
20 #include "clang/StaticAnalyzer/Core/PathSensitive/BlockCounter.h"
21 #include "clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h"
22 #include "clang/StaticAnalyzer/Core/PathSensitive/FunctionSummary.h"
23 #include "clang/StaticAnalyzer/Core/PathSensitive/WorkList.h"
24 #include "llvm/ADT/OwningPtr.h"
28 class ProgramPointTag;
34 //===----------------------------------------------------------------------===//
35 /// CoreEngine - Implements the core logic of the graph-reachability
36 /// analysis. It traverses the CFG and generates the ExplodedGraph.
37 /// Program "states" are treated as opaque void pointers.
38 /// The template class CoreEngine (which subclasses CoreEngine)
39 /// provides the matching component to the engine that knows the actual types
40 /// for states. Note that this engine only dispatches to transfer functions
41 /// at the statement and block-level. The analyses themselves must implement
42 /// any transfer function logic and the sub-expression level (if any).
44 friend struct NodeBuilderContext;
45 friend class NodeBuilder;
46 friend class ExprEngine;
47 friend class CommonNodeBuilder;
48 friend class IndirectGotoNodeBuilder;
49 friend class SwitchNodeBuilder;
50 friend class EndOfFunctionNodeBuilder;
52 typedef std::vector<std::pair<BlockEdge, const ExplodedNode*> >
55 typedef std::vector<std::pair<const CFGBlock*, const ExplodedNode*> >
62 /// G - The simulation graph. Each node is a (location,state) pair.
63 OwningPtr<ExplodedGraph> G;
65 /// WList - A set of queued nodes that need to be processed by the
66 /// worklist algorithm. It is up to the implementation of WList to decide
67 /// the order that nodes are processed.
68 OwningPtr<WorkList> WList;
70 /// BCounterFactory - A factory object for created BlockCounter objects.
71 /// These are used to record for key nodes in the ExplodedGraph the
72 /// number of times different CFGBlocks have been visited along a path.
73 BlockCounter::Factory BCounterFactory;
75 /// The locations where we stopped doing work because we visited a location
77 BlocksExhausted blocksExhausted;
79 /// The locations where we stopped because the engine aborted analysis,
80 /// usually because it could not reason about something.
81 BlocksAborted blocksAborted;
83 /// The information about functions shared by the whole translation unit.
84 /// (This data is owned by AnalysisConsumer.)
85 FunctionSummariesTy *FunctionSummaries;
87 void generateNode(const ProgramPoint &Loc,
88 ProgramStateRef State,
91 void HandleBlockEdge(const BlockEdge &E, ExplodedNode *Pred);
92 void HandleBlockEntrance(const BlockEntrance &E, ExplodedNode *Pred);
93 void HandleBlockExit(const CFGBlock *B, ExplodedNode *Pred);
94 void HandlePostStmt(const CFGBlock *B, unsigned StmtIdx, ExplodedNode *Pred);
96 void HandleBranch(const Stmt *Cond, const Stmt *Term, const CFGBlock *B,
99 /// Handle conditional logic for running static initializers.
100 void HandleStaticInit(const DeclStmt *DS, const CFGBlock *B,
104 CoreEngine(const CoreEngine &) LLVM_DELETED_FUNCTION;
105 void operator=(const CoreEngine &) LLVM_DELETED_FUNCTION;
107 ExplodedNode *generateCallExitBeginNode(ExplodedNode *N);
110 /// Construct a CoreEngine object to analyze the provided CFG.
111 CoreEngine(SubEngine& subengine,
112 FunctionSummariesTy *FS)
113 : SubEng(subengine), G(new ExplodedGraph()),
114 WList(WorkList::makeDFS()),
115 BCounterFactory(G->getAllocator()),
116 FunctionSummaries(FS){}
118 /// getGraph - Returns the exploded graph.
119 ExplodedGraph& getGraph() { return *G.get(); }
121 /// takeGraph - Returns the exploded graph. Ownership of the graph is
122 /// transferred to the caller.
123 ExplodedGraph* takeGraph() { return G.take(); }
125 /// ExecuteWorkList - Run the worklist algorithm for a maximum number of
126 /// steps. Returns true if there is still simulation state on the worklist.
127 bool ExecuteWorkList(const LocationContext *L, unsigned Steps,
128 ProgramStateRef InitState);
129 /// Returns true if there is still simulation state on the worklist.
130 bool ExecuteWorkListWithInitialState(const LocationContext *L,
132 ProgramStateRef InitState,
133 ExplodedNodeSet &Dst);
135 /// Dispatch the work list item based on the given location information.
136 /// Use Pred parameter as the predecessor state.
137 void dispatchWorkItem(ExplodedNode* Pred, ProgramPoint Loc,
138 const WorkListUnit& WU);
140 // Functions for external checking of whether we have unfinished work
141 bool wasBlockAborted() const { return !blocksAborted.empty(); }
142 bool wasBlocksExhausted() const { return !blocksExhausted.empty(); }
143 bool hasWorkRemaining() const { return wasBlocksExhausted() ||
147 /// Inform the CoreEngine that a basic block was aborted because
148 /// it could not be completely analyzed.
149 void addAbortedBlock(const ExplodedNode *node, const CFGBlock *block) {
150 blocksAborted.push_back(std::make_pair(block, node));
153 WorkList *getWorkList() const { return WList.get(); }
155 BlocksExhausted::const_iterator blocks_exhausted_begin() const {
156 return blocksExhausted.begin();
158 BlocksExhausted::const_iterator blocks_exhausted_end() const {
159 return blocksExhausted.end();
161 BlocksAborted::const_iterator blocks_aborted_begin() const {
162 return blocksAborted.begin();
164 BlocksAborted::const_iterator blocks_aborted_end() const {
165 return blocksAborted.end();
168 /// \brief Enqueue the given set of nodes onto the work list.
169 void enqueue(ExplodedNodeSet &Set);
171 /// \brief Enqueue nodes that were created as a result of processing
172 /// a statement onto the work list.
173 void enqueue(ExplodedNodeSet &Set, const CFGBlock *Block, unsigned Idx);
175 /// \brief enqueue the nodes corresponding to the end of function onto the
176 /// end of path / work list.
177 void enqueueEndOfFunction(ExplodedNodeSet &Set);
179 /// \brief Enqueue a single node created as a result of statement processing.
180 void enqueueStmtNode(ExplodedNode *N, const CFGBlock *Block, unsigned Idx);
183 // TODO: Turn into a calss.
184 struct NodeBuilderContext {
185 const CoreEngine &Eng;
186 const CFGBlock *Block;
187 const LocationContext *LC;
188 NodeBuilderContext(const CoreEngine &E, const CFGBlock *B, ExplodedNode *N)
189 : Eng(E), Block(B), LC(N->getLocationContext()) { assert(B); }
191 /// \brief Return the CFGBlock associated with this builder.
192 const CFGBlock *getBlock() const { return Block; }
194 /// \brief Returns the number of times the current basic block has been
195 /// visited on the exploded graph path.
196 unsigned blockCount() const {
197 return Eng.WList->getBlockCounter().getNumVisited(
198 LC->getCurrentStackFrame(),
199 Block->getBlockID());
203 /// \class NodeBuilder
204 /// \brief This is the simplest builder which generates nodes in the
207 /// The main benefit of the builder is that it automatically tracks the
208 /// frontier nodes (or destination set). This is the set of nodes which should
209 /// be propagated to the next step / builder. They are the nodes which have been
210 /// added to the builder (either as the input node set or as the newly
211 /// constructed nodes) but did not have any outgoing transitions added.
213 virtual void anchor();
215 const NodeBuilderContext &C;
217 /// Specifies if the builder results have been finalized. For example, if it
218 /// is set to false, autotransitions are yet to be generated.
220 bool HasGeneratedNodes;
221 /// \brief The frontier set - a set of nodes which need to be propagated after
222 /// the builder dies.
223 ExplodedNodeSet &Frontier;
225 /// Checkes if the results are ready.
226 virtual bool checkResults() {
232 bool hasNoSinksInFrontier() {
233 for (iterator I = Frontier.begin(), E = Frontier.end(); I != E; ++I) {
240 /// Allow subclasses to finalize results before result_begin() is executed.
241 virtual void finalizeResults() {}
243 ExplodedNode *generateNodeImpl(const ProgramPoint &PP,
244 ProgramStateRef State,
246 bool MarkAsSink = false);
249 NodeBuilder(ExplodedNode *SrcNode, ExplodedNodeSet &DstSet,
250 const NodeBuilderContext &Ctx, bool F = true)
251 : C(Ctx), Finalized(F), HasGeneratedNodes(false), Frontier(DstSet) {
252 Frontier.Add(SrcNode);
255 NodeBuilder(const ExplodedNodeSet &SrcSet, ExplodedNodeSet &DstSet,
256 const NodeBuilderContext &Ctx, bool F = true)
257 : C(Ctx), Finalized(F), HasGeneratedNodes(false), Frontier(DstSet) {
258 Frontier.insert(SrcSet);
259 assert(hasNoSinksInFrontier());
262 virtual ~NodeBuilder() {}
264 /// \brief Generates a node in the ExplodedGraph.
265 ExplodedNode *generateNode(const ProgramPoint &PP,
266 ProgramStateRef State,
267 ExplodedNode *Pred) {
268 return generateNodeImpl(PP, State, Pred, false);
271 /// \brief Generates a sink in the ExplodedGraph.
273 /// When a node is marked as sink, the exploration from the node is stopped -
274 /// the node becomes the last node on the path and certain kinds of bugs are
276 ExplodedNode *generateSink(const ProgramPoint &PP,
277 ProgramStateRef State,
278 ExplodedNode *Pred) {
279 return generateNodeImpl(PP, State, Pred, true);
282 const ExplodedNodeSet &getResults() {
284 assert(checkResults());
288 typedef ExplodedNodeSet::iterator iterator;
289 /// \brief Iterators through the results frontier.
290 inline iterator begin() {
292 assert(checkResults());
293 return Frontier.begin();
295 inline iterator end() {
297 return Frontier.end();
300 const NodeBuilderContext &getContext() { return C; }
301 bool hasGeneratedNodes() { return HasGeneratedNodes; }
303 void takeNodes(const ExplodedNodeSet &S) {
304 for (ExplodedNodeSet::iterator I = S.begin(), E = S.end(); I != E; ++I )
307 void takeNodes(ExplodedNode *N) { Frontier.erase(N); }
308 void addNodes(const ExplodedNodeSet &S) { Frontier.insert(S); }
309 void addNodes(ExplodedNode *N) { Frontier.Add(N); }
312 /// \class NodeBuilderWithSinks
313 /// \brief This node builder keeps track of the generated sink nodes.
314 class NodeBuilderWithSinks: public NodeBuilder {
315 virtual void anchor();
317 SmallVector<ExplodedNode*, 2> sinksGenerated;
318 ProgramPoint &Location;
321 NodeBuilderWithSinks(ExplodedNode *Pred, ExplodedNodeSet &DstSet,
322 const NodeBuilderContext &Ctx, ProgramPoint &L)
323 : NodeBuilder(Pred, DstSet, Ctx), Location(L) {}
325 ExplodedNode *generateNode(ProgramStateRef State,
327 const ProgramPointTag *Tag = 0) {
328 const ProgramPoint &LocalLoc = (Tag ? Location.withTag(Tag) : Location);
329 return NodeBuilder::generateNode(LocalLoc, State, Pred);
332 ExplodedNode *generateSink(ProgramStateRef State, ExplodedNode *Pred,
333 const ProgramPointTag *Tag = 0) {
334 const ProgramPoint &LocalLoc = (Tag ? Location.withTag(Tag) : Location);
335 ExplodedNode *N = NodeBuilder::generateSink(LocalLoc, State, Pred);
336 if (N && N->isSink())
337 sinksGenerated.push_back(N);
341 const SmallVectorImpl<ExplodedNode*> &getSinks() const {
342 return sinksGenerated;
346 /// \class StmtNodeBuilder
347 /// \brief This builder class is useful for generating nodes that resulted from
348 /// visiting a statement. The main difference from its parent NodeBuilder is
349 /// that it creates a statement specific ProgramPoint.
350 class StmtNodeBuilder: public NodeBuilder {
351 NodeBuilder *EnclosingBldr;
354 /// \brief Constructs a StmtNodeBuilder. If the builder is going to process
355 /// nodes currently owned by another builder(with larger scope), use
356 /// Enclosing builder to transfer ownership.
357 StmtNodeBuilder(ExplodedNode *SrcNode, ExplodedNodeSet &DstSet,
358 const NodeBuilderContext &Ctx, NodeBuilder *Enclosing = 0)
359 : NodeBuilder(SrcNode, DstSet, Ctx), EnclosingBldr(Enclosing) {
361 EnclosingBldr->takeNodes(SrcNode);
364 StmtNodeBuilder(ExplodedNodeSet &SrcSet, ExplodedNodeSet &DstSet,
365 const NodeBuilderContext &Ctx, NodeBuilder *Enclosing = 0)
366 : NodeBuilder(SrcSet, DstSet, Ctx), EnclosingBldr(Enclosing) {
368 for (ExplodedNodeSet::iterator I = SrcSet.begin(),
369 E = SrcSet.end(); I != E; ++I )
370 EnclosingBldr->takeNodes(*I);
373 virtual ~StmtNodeBuilder();
375 using NodeBuilder::generateNode;
376 using NodeBuilder::generateSink;
378 ExplodedNode *generateNode(const Stmt *S,
381 const ProgramPointTag *tag = 0,
382 ProgramPoint::Kind K = ProgramPoint::PostStmtKind){
383 const ProgramPoint &L = ProgramPoint::getProgramPoint(S, K,
384 Pred->getLocationContext(), tag);
385 return NodeBuilder::generateNode(L, St, Pred);
388 ExplodedNode *generateSink(const Stmt *S,
391 const ProgramPointTag *tag = 0,
392 ProgramPoint::Kind K = ProgramPoint::PostStmtKind){
393 const ProgramPoint &L = ProgramPoint::getProgramPoint(S, K,
394 Pred->getLocationContext(), tag);
395 return NodeBuilder::generateSink(L, St, Pred);
399 /// \brief BranchNodeBuilder is responsible for constructing the nodes
400 /// corresponding to the two branches of the if statement - true and false.
401 class BranchNodeBuilder: public NodeBuilder {
402 virtual void anchor();
403 const CFGBlock *DstT;
404 const CFGBlock *DstF;
407 bool InFeasibleFalse;
410 BranchNodeBuilder(ExplodedNode *SrcNode, ExplodedNodeSet &DstSet,
411 const NodeBuilderContext &C,
412 const CFGBlock *dstT, const CFGBlock *dstF)
413 : NodeBuilder(SrcNode, DstSet, C), DstT(dstT), DstF(dstF),
414 InFeasibleTrue(!DstT), InFeasibleFalse(!DstF) {
415 // The branch node builder does not generate autotransitions.
416 // If there are no successors it means that both branches are infeasible.
420 BranchNodeBuilder(const ExplodedNodeSet &SrcSet, ExplodedNodeSet &DstSet,
421 const NodeBuilderContext &C,
422 const CFGBlock *dstT, const CFGBlock *dstF)
423 : NodeBuilder(SrcSet, DstSet, C), DstT(dstT), DstF(dstF),
424 InFeasibleTrue(!DstT), InFeasibleFalse(!DstF) {
428 ExplodedNode *generateNode(ProgramStateRef State, bool branch,
431 const CFGBlock *getTargetBlock(bool branch) const {
432 return branch ? DstT : DstF;
435 void markInfeasible(bool branch) {
437 InFeasibleTrue = true;
439 InFeasibleFalse = true;
442 bool isFeasible(bool branch) {
443 return branch ? !InFeasibleTrue : !InFeasibleFalse;
447 class IndirectGotoNodeBuilder {
450 const CFGBlock &DispatchBlock;
455 IndirectGotoNodeBuilder(ExplodedNode *pred, const CFGBlock *src,
456 const Expr *e, const CFGBlock *dispatch, CoreEngine* eng)
457 : Eng(*eng), Src(src), DispatchBlock(*dispatch), E(e), Pred(pred) {}
460 CFGBlock::const_succ_iterator I;
462 friend class IndirectGotoNodeBuilder;
463 iterator(CFGBlock::const_succ_iterator i) : I(i) {}
466 iterator &operator++() { ++I; return *this; }
467 bool operator!=(const iterator &X) const { return I != X.I; }
469 const LabelDecl *getLabel() const {
470 return cast<LabelStmt>((*I)->getLabel())->getDecl();
473 const CFGBlock *getBlock() const {
478 iterator begin() { return iterator(DispatchBlock.succ_begin()); }
479 iterator end() { return iterator(DispatchBlock.succ_end()); }
481 ExplodedNode *generateNode(const iterator &I,
482 ProgramStateRef State,
483 bool isSink = false);
485 const Expr *getTarget() const { return E; }
487 ProgramStateRef getState() const { return Pred->State; }
489 const LocationContext *getLocationContext() const {
490 return Pred->getLocationContext();
494 class SwitchNodeBuilder {
497 const Expr *Condition;
501 SwitchNodeBuilder(ExplodedNode *pred, const CFGBlock *src,
502 const Expr *condition, CoreEngine* eng)
503 : Eng(*eng), Src(src), Condition(condition), Pred(pred) {}
506 CFGBlock::const_succ_reverse_iterator I;
508 friend class SwitchNodeBuilder;
509 iterator(CFGBlock::const_succ_reverse_iterator i) : I(i) {}
512 iterator &operator++() { ++I; return *this; }
513 bool operator!=(const iterator &X) const { return I != X.I; }
514 bool operator==(const iterator &X) const { return I == X.I; }
516 const CaseStmt *getCase() const {
517 return cast<CaseStmt>((*I)->getLabel());
520 const CFGBlock *getBlock() const {
525 iterator begin() { return iterator(Src->succ_rbegin()+1); }
526 iterator end() { return iterator(Src->succ_rend()); }
528 const SwitchStmt *getSwitch() const {
529 return cast<SwitchStmt>(Src->getTerminator());
532 ExplodedNode *generateCaseStmtNode(const iterator &I,
533 ProgramStateRef State);
535 ExplodedNode *generateDefaultCaseNode(ProgramStateRef State,
536 bool isSink = false);
538 const Expr *getCondition() const { return Condition; }
540 ProgramStateRef getState() const { return Pred->State; }
542 const LocationContext *getLocationContext() const {
543 return Pred->getLocationContext();
547 } // end ento namespace
548 } // end clang namespace