1 //===- CoreEngine.h - Path-Sensitive Dataflow Engine ------------*- C++ -*-===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This file defines a generic engine for intraprocedural, path-sensitive,
10 // dataflow analysis via graph reachability.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_COREENGINE_H
15 #define LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_COREENGINE_H
17 #include "clang/AST/Stmt.h"
18 #include "clang/Analysis/AnalysisDeclContext.h"
19 #include "clang/Analysis/CFG.h"
20 #include "clang/Analysis/ProgramPoint.h"
21 #include "clang/Basic/LLVM.h"
22 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
23 #include "clang/StaticAnalyzer/Core/PathSensitive/BlockCounter.h"
24 #include "clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h"
25 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState_Fwd.h"
26 #include "clang/StaticAnalyzer/Core/PathSensitive/WorkList.h"
27 #include "llvm/ADT/SmallVector.h"
28 #include "llvm/Support/Casting.h"
36 class AnalyzerOptions;
37 class CXXBindTemporaryExpr;
43 class FunctionSummariesTy;
46 //===----------------------------------------------------------------------===//
47 /// CoreEngine - Implements the core logic of the graph-reachability
48 /// analysis. It traverses the CFG and generates the ExplodedGraph.
49 /// Program "states" are treated as opaque void pointers.
50 /// The template class CoreEngine (which subclasses CoreEngine)
51 /// provides the matching component to the engine that knows the actual types
52 /// for states. Note that this engine only dispatches to transfer functions
53 /// at the statement and block-level. The analyses themselves must implement
54 /// any transfer function logic and the sub-expression level (if any).
56 friend class CommonNodeBuilder;
57 friend class EndOfFunctionNodeBuilder;
58 friend class ExprEngine;
59 friend class IndirectGotoNodeBuilder;
60 friend class NodeBuilder;
61 friend struct NodeBuilderContext;
62 friend class SwitchNodeBuilder;
65 using BlocksExhausted =
66 std::vector<std::pair<BlockEdge, const ExplodedNode *>>;
69 std::vector<std::pair<const CFGBlock *, const ExplodedNode *>>;
74 /// G - The simulation graph. Each node is a (location,state) pair.
75 mutable ExplodedGraph G;
77 /// WList - A set of queued nodes that need to be processed by the
78 /// worklist algorithm. It is up to the implementation of WList to decide
79 /// the order that nodes are processed.
80 std::unique_ptr<WorkList> WList;
82 /// BCounterFactory - A factory object for created BlockCounter objects.
83 /// These are used to record for key nodes in the ExplodedGraph the
84 /// number of times different CFGBlocks have been visited along a path.
85 BlockCounter::Factory BCounterFactory;
87 /// The locations where we stopped doing work because we visited a location
89 BlocksExhausted blocksExhausted;
91 /// The locations where we stopped because the engine aborted analysis,
92 /// usually because it could not reason about something.
93 BlocksAborted blocksAborted;
95 /// The information about functions shared by the whole translation unit.
96 /// (This data is owned by AnalysisConsumer.)
97 FunctionSummariesTy *FunctionSummaries;
99 /// Add path note tags along the path when we see that something interesting
100 /// is happening. This field is the allocator for such tags.
101 NoteTag::Factory NoteTags;
103 void generateNode(const ProgramPoint &Loc,
104 ProgramStateRef State,
107 void HandleBlockEdge(const BlockEdge &E, ExplodedNode *Pred);
108 void HandleBlockEntrance(const BlockEntrance &E, ExplodedNode *Pred);
109 void HandleBlockExit(const CFGBlock *B, ExplodedNode *Pred);
111 void HandleCallEnter(const CallEnter &CE, ExplodedNode *Pred);
113 void HandlePostStmt(const CFGBlock *B, unsigned StmtIdx, ExplodedNode *Pred);
115 void HandleBranch(const Stmt *Cond, const Stmt *Term, const CFGBlock *B,
117 void HandleCleanupTemporaryBranch(const CXXBindTemporaryExpr *BTE,
118 const CFGBlock *B, ExplodedNode *Pred);
120 /// Handle conditional logic for running static initializers.
121 void HandleStaticInit(const DeclStmt *DS, const CFGBlock *B,
124 void HandleVirtualBaseBranch(const CFGBlock *B, ExplodedNode *Pred);
127 ExplodedNode *generateCallExitBeginNode(ExplodedNode *N,
128 const ReturnStmt *RS);
131 /// Construct a CoreEngine object to analyze the provided CFG.
132 CoreEngine(SubEngine &subengine,
133 FunctionSummariesTy *FS,
134 AnalyzerOptions &Opts);
136 CoreEngine(const CoreEngine &) = delete;
137 CoreEngine &operator=(const CoreEngine &) = delete;
139 /// getGraph - Returns the exploded graph.
140 ExplodedGraph &getGraph() { return G; }
142 /// ExecuteWorkList - Run the worklist algorithm for a maximum number of
143 /// steps. Returns true if there is still simulation state on the worklist.
144 bool ExecuteWorkList(const LocationContext *L, unsigned Steps,
145 ProgramStateRef InitState);
147 /// Returns true if there is still simulation state on the worklist.
148 bool ExecuteWorkListWithInitialState(const LocationContext *L,
150 ProgramStateRef InitState,
151 ExplodedNodeSet &Dst);
153 /// Dispatch the work list item based on the given location information.
154 /// Use Pred parameter as the predecessor state.
155 void dispatchWorkItem(ExplodedNode* Pred, ProgramPoint Loc,
156 const WorkListUnit& WU);
158 // Functions for external checking of whether we have unfinished work
159 bool wasBlockAborted() const { return !blocksAborted.empty(); }
160 bool wasBlocksExhausted() const { return !blocksExhausted.empty(); }
161 bool hasWorkRemaining() const { return wasBlocksExhausted() ||
165 /// Inform the CoreEngine that a basic block was aborted because
166 /// it could not be completely analyzed.
167 void addAbortedBlock(const ExplodedNode *node, const CFGBlock *block) {
168 blocksAborted.push_back(std::make_pair(block, node));
171 WorkList *getWorkList() const { return WList.get(); }
173 BlocksExhausted::const_iterator blocks_exhausted_begin() const {
174 return blocksExhausted.begin();
177 BlocksExhausted::const_iterator blocks_exhausted_end() const {
178 return blocksExhausted.end();
181 BlocksAborted::const_iterator blocks_aborted_begin() const {
182 return blocksAborted.begin();
185 BlocksAborted::const_iterator blocks_aborted_end() const {
186 return blocksAborted.end();
189 /// Enqueue the given set of nodes onto the work list.
190 void enqueue(ExplodedNodeSet &Set);
192 /// Enqueue nodes that were created as a result of processing
193 /// a statement onto the work list.
194 void enqueue(ExplodedNodeSet &Set, const CFGBlock *Block, unsigned Idx);
196 /// enqueue the nodes corresponding to the end of function onto the
197 /// end of path / work list.
198 void enqueueEndOfFunction(ExplodedNodeSet &Set, const ReturnStmt *RS);
200 /// Enqueue a single node created as a result of statement processing.
201 void enqueueStmtNode(ExplodedNode *N, const CFGBlock *Block, unsigned Idx);
203 NoteTag::Factory &getNoteTags() { return NoteTags; }
206 // TODO: Turn into a class.
207 struct NodeBuilderContext {
208 const CoreEngine &Eng;
209 const CFGBlock *Block;
210 const LocationContext *LC;
212 NodeBuilderContext(const CoreEngine &E, const CFGBlock *B, ExplodedNode *N)
213 : Eng(E), Block(B), LC(N->getLocationContext()) { assert(B); }
215 /// Return the CFGBlock associated with this builder.
216 const CFGBlock *getBlock() const { return Block; }
218 /// Returns the number of times the current basic block has been
219 /// visited on the exploded graph path.
220 unsigned blockCount() const {
221 return Eng.WList->getBlockCounter().getNumVisited(
223 Block->getBlockID());
227 /// \class NodeBuilder
228 /// This is the simplest builder which generates nodes in the
231 /// The main benefit of the builder is that it automatically tracks the
232 /// frontier nodes (or destination set). This is the set of nodes which should
233 /// be propagated to the next step / builder. They are the nodes which have been
234 /// added to the builder (either as the input node set or as the newly
235 /// constructed nodes) but did not have any outgoing transitions added.
237 virtual void anchor();
240 const NodeBuilderContext &C;
242 /// Specifies if the builder results have been finalized. For example, if it
243 /// is set to false, autotransitions are yet to be generated.
246 bool HasGeneratedNodes = false;
248 /// The frontier set - a set of nodes which need to be propagated after
249 /// the builder dies.
250 ExplodedNodeSet &Frontier;
252 /// Checks if the results are ready.
253 virtual bool checkResults() {
257 bool hasNoSinksInFrontier() {
258 for (const auto I : Frontier)
264 /// Allow subclasses to finalize results before result_begin() is executed.
265 virtual void finalizeResults() {}
267 ExplodedNode *generateNodeImpl(const ProgramPoint &PP,
268 ProgramStateRef State,
270 bool MarkAsSink = false);
273 NodeBuilder(ExplodedNode *SrcNode, ExplodedNodeSet &DstSet,
274 const NodeBuilderContext &Ctx, bool F = true)
275 : C(Ctx), Finalized(F), Frontier(DstSet) {
276 Frontier.Add(SrcNode);
279 NodeBuilder(const ExplodedNodeSet &SrcSet, ExplodedNodeSet &DstSet,
280 const NodeBuilderContext &Ctx, bool F = true)
281 : C(Ctx), Finalized(F), Frontier(DstSet) {
282 Frontier.insert(SrcSet);
283 assert(hasNoSinksInFrontier());
286 virtual ~NodeBuilder() = default;
288 /// Generates a node in the ExplodedGraph.
289 ExplodedNode *generateNode(const ProgramPoint &PP,
290 ProgramStateRef State,
291 ExplodedNode *Pred) {
292 return generateNodeImpl(PP, State, Pred, false);
295 /// Generates a sink in the ExplodedGraph.
297 /// When a node is marked as sink, the exploration from the node is stopped -
298 /// the node becomes the last node on the path and certain kinds of bugs are
300 ExplodedNode *generateSink(const ProgramPoint &PP,
301 ProgramStateRef State,
302 ExplodedNode *Pred) {
303 return generateNodeImpl(PP, State, Pred, true);
306 const ExplodedNodeSet &getResults() {
308 assert(checkResults());
312 using iterator = ExplodedNodeSet::iterator;
314 /// Iterators through the results frontier.
317 assert(checkResults());
318 return Frontier.begin();
323 return Frontier.end();
326 const NodeBuilderContext &getContext() { return C; }
327 bool hasGeneratedNodes() { return HasGeneratedNodes; }
329 void takeNodes(const ExplodedNodeSet &S) {
330 for (const auto I : S)
334 void takeNodes(ExplodedNode *N) { Frontier.erase(N); }
335 void addNodes(const ExplodedNodeSet &S) { Frontier.insert(S); }
336 void addNodes(ExplodedNode *N) { Frontier.Add(N); }
339 /// \class NodeBuilderWithSinks
340 /// This node builder keeps track of the generated sink nodes.
341 class NodeBuilderWithSinks: public NodeBuilder {
342 void anchor() override;
345 SmallVector<ExplodedNode*, 2> sinksGenerated;
346 ProgramPoint &Location;
349 NodeBuilderWithSinks(ExplodedNode *Pred, ExplodedNodeSet &DstSet,
350 const NodeBuilderContext &Ctx, ProgramPoint &L)
351 : NodeBuilder(Pred, DstSet, Ctx), Location(L) {}
353 ExplodedNode *generateNode(ProgramStateRef State,
355 const ProgramPointTag *Tag = nullptr) {
356 const ProgramPoint &LocalLoc = (Tag ? Location.withTag(Tag) : Location);
357 return NodeBuilder::generateNode(LocalLoc, State, Pred);
360 ExplodedNode *generateSink(ProgramStateRef State, ExplodedNode *Pred,
361 const ProgramPointTag *Tag = nullptr) {
362 const ProgramPoint &LocalLoc = (Tag ? Location.withTag(Tag) : Location);
363 ExplodedNode *N = NodeBuilder::generateSink(LocalLoc, State, Pred);
364 if (N && N->isSink())
365 sinksGenerated.push_back(N);
369 const SmallVectorImpl<ExplodedNode*> &getSinks() const {
370 return sinksGenerated;
374 /// \class StmtNodeBuilder
375 /// This builder class is useful for generating nodes that resulted from
376 /// visiting a statement. The main difference from its parent NodeBuilder is
377 /// that it creates a statement specific ProgramPoint.
378 class StmtNodeBuilder: public NodeBuilder {
379 NodeBuilder *EnclosingBldr;
382 /// Constructs a StmtNodeBuilder. If the builder is going to process
383 /// nodes currently owned by another builder(with larger scope), use
384 /// Enclosing builder to transfer ownership.
385 StmtNodeBuilder(ExplodedNode *SrcNode, ExplodedNodeSet &DstSet,
386 const NodeBuilderContext &Ctx,
387 NodeBuilder *Enclosing = nullptr)
388 : NodeBuilder(SrcNode, DstSet, Ctx), EnclosingBldr(Enclosing) {
390 EnclosingBldr->takeNodes(SrcNode);
393 StmtNodeBuilder(ExplodedNodeSet &SrcSet, ExplodedNodeSet &DstSet,
394 const NodeBuilderContext &Ctx,
395 NodeBuilder *Enclosing = nullptr)
396 : NodeBuilder(SrcSet, DstSet, Ctx), EnclosingBldr(Enclosing) {
398 for (const auto I : SrcSet)
399 EnclosingBldr->takeNodes(I);
402 ~StmtNodeBuilder() override;
404 using NodeBuilder::generateNode;
405 using NodeBuilder::generateSink;
407 ExplodedNode *generateNode(const Stmt *S,
410 const ProgramPointTag *tag = nullptr,
411 ProgramPoint::Kind K = ProgramPoint::PostStmtKind){
412 const ProgramPoint &L = ProgramPoint::getProgramPoint(S, K,
413 Pred->getLocationContext(), tag);
414 return NodeBuilder::generateNode(L, St, Pred);
417 ExplodedNode *generateSink(const Stmt *S,
420 const ProgramPointTag *tag = nullptr,
421 ProgramPoint::Kind K = ProgramPoint::PostStmtKind){
422 const ProgramPoint &L = ProgramPoint::getProgramPoint(S, K,
423 Pred->getLocationContext(), tag);
424 return NodeBuilder::generateSink(L, St, Pred);
428 /// BranchNodeBuilder is responsible for constructing the nodes
429 /// corresponding to the two branches of the if statement - true and false.
430 class BranchNodeBuilder: public NodeBuilder {
431 const CFGBlock *DstT;
432 const CFGBlock *DstF;
435 bool InFeasibleFalse;
437 void anchor() override;
440 BranchNodeBuilder(ExplodedNode *SrcNode, ExplodedNodeSet &DstSet,
441 const NodeBuilderContext &C,
442 const CFGBlock *dstT, const CFGBlock *dstF)
443 : NodeBuilder(SrcNode, DstSet, C), DstT(dstT), DstF(dstF),
444 InFeasibleTrue(!DstT), InFeasibleFalse(!DstF) {
445 // The branch node builder does not generate autotransitions.
446 // If there are no successors it means that both branches are infeasible.
450 BranchNodeBuilder(const ExplodedNodeSet &SrcSet, ExplodedNodeSet &DstSet,
451 const NodeBuilderContext &C,
452 const CFGBlock *dstT, const CFGBlock *dstF)
453 : NodeBuilder(SrcSet, DstSet, C), DstT(dstT), DstF(dstF),
454 InFeasibleTrue(!DstT), InFeasibleFalse(!DstF) {
458 ExplodedNode *generateNode(ProgramStateRef State, bool branch,
461 const CFGBlock *getTargetBlock(bool branch) const {
462 return branch ? DstT : DstF;
465 void markInfeasible(bool branch) {
467 InFeasibleTrue = true;
469 InFeasibleFalse = true;
472 bool isFeasible(bool branch) {
473 return branch ? !InFeasibleTrue : !InFeasibleFalse;
477 class IndirectGotoNodeBuilder {
480 const CFGBlock &DispatchBlock;
485 IndirectGotoNodeBuilder(ExplodedNode *pred, const CFGBlock *src,
486 const Expr *e, const CFGBlock *dispatch, CoreEngine* eng)
487 : Eng(*eng), Src(src), DispatchBlock(*dispatch), E(e), Pred(pred) {}
490 friend class IndirectGotoNodeBuilder;
492 CFGBlock::const_succ_iterator I;
494 iterator(CFGBlock::const_succ_iterator i) : I(i) {}
497 iterator &operator++() { ++I; return *this; }
498 bool operator!=(const iterator &X) const { return I != X.I; }
500 const LabelDecl *getLabel() const {
501 return cast<LabelStmt>((*I)->getLabel())->getDecl();
504 const CFGBlock *getBlock() const {
509 iterator begin() { return iterator(DispatchBlock.succ_begin()); }
510 iterator end() { return iterator(DispatchBlock.succ_end()); }
512 ExplodedNode *generateNode(const iterator &I,
513 ProgramStateRef State,
514 bool isSink = false);
516 const Expr *getTarget() const { return E; }
518 ProgramStateRef getState() const { return Pred->State; }
520 const LocationContext *getLocationContext() const {
521 return Pred->getLocationContext();
525 class SwitchNodeBuilder {
528 const Expr *Condition;
532 SwitchNodeBuilder(ExplodedNode *pred, const CFGBlock *src,
533 const Expr *condition, CoreEngine* eng)
534 : Eng(*eng), Src(src), Condition(condition), Pred(pred) {}
537 friend class SwitchNodeBuilder;
539 CFGBlock::const_succ_reverse_iterator I;
541 iterator(CFGBlock::const_succ_reverse_iterator i) : I(i) {}
544 iterator &operator++() { ++I; return *this; }
545 bool operator!=(const iterator &X) const { return I != X.I; }
546 bool operator==(const iterator &X) const { return I == X.I; }
548 const CaseStmt *getCase() const {
549 return cast<CaseStmt>((*I)->getLabel());
552 const CFGBlock *getBlock() const {
557 iterator begin() { return iterator(Src->succ_rbegin()+1); }
558 iterator end() { return iterator(Src->succ_rend()); }
560 const SwitchStmt *getSwitch() const {
561 return cast<SwitchStmt>(Src->getTerminator());
564 ExplodedNode *generateCaseStmtNode(const iterator &I,
565 ProgramStateRef State);
567 ExplodedNode *generateDefaultCaseNode(ProgramStateRef State,
568 bool isSink = false);
570 const Expr *getCondition() const { return Condition; }
572 ProgramStateRef getState() const { return Pred->State; }
574 const LocationContext *getLocationContext() const {
575 return Pred->getLocationContext();
583 #endif // LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_COREENGINE_H