clang  10.0.0svn
MoveChecker.cpp
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1 // MoveChecker.cpp - Check use of moved-from objects. - C++ ---------------===//
2 //
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
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This defines checker which checks for potential misuses of a moved-from
10 // object. That means method calls on the object or copying it in moved-from
11 // state.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "clang/AST/ExprCXX.h"
23 #include "llvm/ADT/StringSet.h"
24 
25 using namespace clang;
26 using namespace ento;
27 
28 namespace {
29 struct RegionState {
30 private:
31  enum Kind { Moved, Reported } K;
32  RegionState(Kind InK) : K(InK) {}
33 
34 public:
35  bool isReported() const { return K == Reported; }
36  bool isMoved() const { return K == Moved; }
37 
38  static RegionState getReported() { return RegionState(Reported); }
39  static RegionState getMoved() { return RegionState(Moved); }
40 
41  bool operator==(const RegionState &X) const { return K == X.K; }
42  void Profile(llvm::FoldingSetNodeID &ID) const { ID.AddInteger(K); }
43 };
44 } // end of anonymous namespace
45 
46 namespace {
47 class MoveChecker
48  : public Checker<check::PreCall, check::PostCall,
49  check::DeadSymbols, check::RegionChanges> {
50 public:
51  void checkEndFunction(const ReturnStmt *RS, CheckerContext &C) const;
52  void checkPreCall(const CallEvent &MC, CheckerContext &C) const;
53  void checkPostCall(const CallEvent &MC, CheckerContext &C) const;
54  void checkDeadSymbols(SymbolReaper &SR, CheckerContext &C) const;
56  checkRegionChanges(ProgramStateRef State,
57  const InvalidatedSymbols *Invalidated,
58  ArrayRef<const MemRegion *> RequestedRegions,
59  ArrayRef<const MemRegion *> InvalidatedRegions,
60  const LocationContext *LCtx, const CallEvent *Call) const;
61  void printState(raw_ostream &Out, ProgramStateRef State,
62  const char *NL, const char *Sep) const override;
63 
64 private:
65  enum MisuseKind { MK_FunCall, MK_Copy, MK_Move, MK_Dereference };
66  enum StdObjectKind { SK_NonStd, SK_Unsafe, SK_Safe, SK_SmartPtr };
67 
68  enum AggressivenessKind { // In any case, don't warn after a reset.
69  AK_Invalid = -1,
70  AK_KnownsOnly = 0, // Warn only about known move-unsafe classes.
71  AK_KnownsAndLocals = 1, // Also warn about all local objects.
72  AK_All = 2, // Warn on any use-after-move.
73  AK_NumKinds = AK_All
74  };
75 
76  static bool misuseCausesCrash(MisuseKind MK) {
77  return MK == MK_Dereference;
78  }
79 
80  struct ObjectKind {
81  // Is this a local variable or a local rvalue reference?
82  bool IsLocal;
83  // Is this an STL object? If so, of what kind?
84  StdObjectKind StdKind;
85  };
86 
87  // STL smart pointers are automatically re-initialized to null when moved
88  // from. So we can't warn on many methods, but we can warn when it is
89  // dereferenced, which is UB even if the resulting lvalue never gets read.
90  const llvm::StringSet<> StdSmartPtrClasses = {
91  "shared_ptr",
92  "unique_ptr",
93  "weak_ptr",
94  };
95 
96  // Not all of these are entirely move-safe, but they do provide *some*
97  // guarantees, and it means that somebody is using them after move
98  // in a valid manner.
99  // TODO: We can still try to identify *unsafe* use after move,
100  // like we did with smart pointers.
101  const llvm::StringSet<> StdSafeClasses = {
102  "basic_filebuf",
103  "basic_ios",
104  "future",
105  "optional",
106  "packaged_task"
107  "promise",
108  "shared_future",
109  "shared_lock",
110  "thread",
111  "unique_lock",
112  };
113 
114  // Should we bother tracking the state of the object?
115  bool shouldBeTracked(ObjectKind OK) const {
116  // In non-aggressive mode, only warn on use-after-move of local variables
117  // (or local rvalue references) and of STL objects. The former is possible
118  // because local variables (or local rvalue references) are not tempting
119  // their user to re-use the storage. The latter is possible because STL
120  // objects are known to end up in a valid but unspecified state after the
121  // move and their state-reset methods are also known, which allows us to
122  // predict precisely when use-after-move is invalid.
123  // Some STL objects are known to conform to additional contracts after move,
124  // so they are not tracked. However, smart pointers specifically are tracked
125  // because we can perform extra checking over them.
126  // In aggressive mode, warn on any use-after-move because the user has
127  // intentionally asked us to completely eliminate use-after-move
128  // in his code.
129  return (Aggressiveness == AK_All) ||
130  (Aggressiveness >= AK_KnownsAndLocals && OK.IsLocal) ||
131  OK.StdKind == SK_Unsafe || OK.StdKind == SK_SmartPtr;
132  }
133 
134  // Some objects only suffer from some kinds of misuses, but we need to track
135  // them anyway because we cannot know in advance what misuse will we find.
136  bool shouldWarnAbout(ObjectKind OK, MisuseKind MK) const {
137  // Additionally, only warn on smart pointers when they are dereferenced (or
138  // local or we are aggressive).
139  return shouldBeTracked(OK) &&
140  ((Aggressiveness == AK_All) ||
141  (Aggressiveness >= AK_KnownsAndLocals && OK.IsLocal) ||
142  OK.StdKind != SK_SmartPtr || MK == MK_Dereference);
143  }
144 
145  // Obtains ObjectKind of an object. Because class declaration cannot always
146  // be easily obtained from the memory region, it is supplied separately.
147  ObjectKind classifyObject(const MemRegion *MR, const CXXRecordDecl *RD) const;
148 
149  // Classifies the object and dumps a user-friendly description string to
150  // the stream.
151  void explainObject(llvm::raw_ostream &OS, const MemRegion *MR,
152  const CXXRecordDecl *RD, MisuseKind MK) const;
153 
154  bool belongsTo(const CXXRecordDecl *RD, const llvm::StringSet<> &Set) const;
155 
156  class MovedBugVisitor : public BugReporterVisitor {
157  public:
158  MovedBugVisitor(const MoveChecker &Chk, const MemRegion *R,
159  const CXXRecordDecl *RD, MisuseKind MK)
160  : Chk(Chk), Region(R), RD(RD), MK(MK), Found(false) {}
161 
162  void Profile(llvm::FoldingSetNodeID &ID) const override {
163  static int X = 0;
164  ID.AddPointer(&X);
165  ID.AddPointer(Region);
166  // Don't add RD because it's, in theory, uniquely determined by
167  // the region. In practice though, it's not always possible to obtain
168  // the declaration directly from the region, that's why we store it
169  // in the first place.
170  }
171 
172  PathDiagnosticPieceRef VisitNode(const ExplodedNode *N,
173  BugReporterContext &BRC,
174  PathSensitiveBugReport &BR) override;
175 
176  private:
177  const MoveChecker &Chk;
178  // The tracked region.
179  const MemRegion *Region;
180  // The class of the tracked object.
181  const CXXRecordDecl *RD;
182  // How exactly the object was misused.
183  const MisuseKind MK;
184  bool Found;
185  };
186 
187  AggressivenessKind Aggressiveness;
188 
189 public:
190  void setAggressiveness(StringRef Str, CheckerManager &Mgr) {
191  Aggressiveness =
192  llvm::StringSwitch<AggressivenessKind>(Str)
193  .Case("KnownsOnly", AK_KnownsOnly)
194  .Case("KnownsAndLocals", AK_KnownsAndLocals)
195  .Case("All", AK_All)
196  .Default(AK_Invalid);
197 
198  if (Aggressiveness == AK_Invalid)
199  Mgr.reportInvalidCheckerOptionValue(this, "WarnOn",
200  "either \"KnownsOnly\", \"KnownsAndLocals\" or \"All\" string value");
201  };
202 
203 private:
204  mutable std::unique_ptr<BugType> BT;
205 
206  // Check if the given form of potential misuse of a given object
207  // should be reported. If so, get it reported. The callback from which
208  // this function was called should immediately return after the call
209  // because this function adds one or two transitions.
210  void modelUse(ProgramStateRef State, const MemRegion *Region,
211  const CXXRecordDecl *RD, MisuseKind MK,
212  CheckerContext &C) const;
213 
214  // Returns the exploded node against which the report was emitted.
215  // The caller *must* add any further transitions against this node.
216  ExplodedNode *reportBug(const MemRegion *Region, const CXXRecordDecl *RD,
217  CheckerContext &C, MisuseKind MK) const;
218 
219  bool isInMoveSafeContext(const LocationContext *LC) const;
220  bool isStateResetMethod(const CXXMethodDecl *MethodDec) const;
221  bool isMoveSafeMethod(const CXXMethodDecl *MethodDec) const;
222  const ExplodedNode *getMoveLocation(const ExplodedNode *N,
223  const MemRegion *Region,
224  CheckerContext &C) const;
225 };
226 } // end anonymous namespace
227 
228 REGISTER_MAP_WITH_PROGRAMSTATE(TrackedRegionMap, const MemRegion *, RegionState)
229 
230 // Define the inter-checker API.
231 namespace clang {
232 namespace ento {
233 namespace move {
235  const RegionState *RS = State->get<TrackedRegionMap>(Region);
236  return RS && (RS->isMoved() || RS->isReported());
237 }
238 } // namespace move
239 } // namespace ento
240 } // namespace clang
241 
242 // If a region is removed all of the subregions needs to be removed too.
244  const MemRegion *Region) {
245  if (!Region)
246  return State;
247  for (auto &E : State->get<TrackedRegionMap>()) {
248  if (E.first->isSubRegionOf(Region))
249  State = State->remove<TrackedRegionMap>(E.first);
250  }
251  return State;
252 }
253 
255  const MemRegion *Region) {
256  for (auto &E : State->get<TrackedRegionMap>()) {
257  if (Region->isSubRegionOf(E.first) && E.second.isReported())
258  return true;
259  }
260  return false;
261 }
262 
263 static const MemRegion *unwrapRValueReferenceIndirection(const MemRegion *MR) {
264  if (const auto *SR = dyn_cast_or_null<SymbolicRegion>(MR)) {
265  SymbolRef Sym = SR->getSymbol();
266  if (Sym->getType()->isRValueReferenceType())
267  if (const MemRegion *OriginMR = Sym->getOriginRegion())
268  return OriginMR;
269  }
270  return MR;
271 }
272 
274 MoveChecker::MovedBugVisitor::VisitNode(const ExplodedNode *N,
275  BugReporterContext &BRC,
276  PathSensitiveBugReport &BR) {
277  // We need only the last move of the reported object's region.
278  // The visitor walks the ExplodedGraph backwards.
279  if (Found)
280  return nullptr;
281  ProgramStateRef State = N->getState();
282  ProgramStateRef StatePrev = N->getFirstPred()->getState();
283  const RegionState *TrackedObject = State->get<TrackedRegionMap>(Region);
284  const RegionState *TrackedObjectPrev =
285  StatePrev->get<TrackedRegionMap>(Region);
286  if (!TrackedObject)
287  return nullptr;
288  if (TrackedObjectPrev && TrackedObject)
289  return nullptr;
290 
291  // Retrieve the associated statement.
292  const Stmt *S = N->getStmtForDiagnostics();
293  if (!S)
294  return nullptr;
295  Found = true;
296 
297  SmallString<128> Str;
298  llvm::raw_svector_ostream OS(Str);
299 
300  ObjectKind OK = Chk.classifyObject(Region, RD);
301  switch (OK.StdKind) {
302  case SK_SmartPtr:
303  if (MK == MK_Dereference) {
304  OS << "Smart pointer";
305  Chk.explainObject(OS, Region, RD, MK);
306  OS << " is reset to null when moved from";
307  break;
308  }
309 
310  // If it's not a dereference, we don't care if it was reset to null
311  // or that it is even a smart pointer.
312  LLVM_FALLTHROUGH;
313  case SK_NonStd:
314  case SK_Safe:
315  OS << "Object";
316  Chk.explainObject(OS, Region, RD, MK);
317  OS << " is moved";
318  break;
319  case SK_Unsafe:
320  OS << "Object";
321  Chk.explainObject(OS, Region, RD, MK);
322  OS << " is left in a valid but unspecified state after move";
323  break;
324  }
325 
326  // Generate the extra diagnostic.
327  PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
328  N->getLocationContext());
329  return std::make_shared<PathDiagnosticEventPiece>(Pos, OS.str(), true);
330 }
331 
332 const ExplodedNode *MoveChecker::getMoveLocation(const ExplodedNode *N,
333  const MemRegion *Region,
334  CheckerContext &C) const {
335  // Walk the ExplodedGraph backwards and find the first node that referred to
336  // the tracked region.
337  const ExplodedNode *MoveNode = N;
338 
339  while (N) {
340  ProgramStateRef State = N->getState();
341  if (!State->get<TrackedRegionMap>(Region))
342  break;
343  MoveNode = N;
344  N = N->pred_empty() ? nullptr : *(N->pred_begin());
345  }
346  return MoveNode;
347 }
348 
349 void MoveChecker::modelUse(ProgramStateRef State, const MemRegion *Region,
350  const CXXRecordDecl *RD, MisuseKind MK,
351  CheckerContext &C) const {
352  assert(!C.isDifferent() && "No transitions should have been made by now");
353  const RegionState *RS = State->get<TrackedRegionMap>(Region);
354  ObjectKind OK = classifyObject(Region, RD);
355 
356  // Just in case: if it's not a smart pointer but it does have operator *,
357  // we shouldn't call the bug a dereference.
358  if (MK == MK_Dereference && OK.StdKind != SK_SmartPtr)
359  MK = MK_FunCall;
360 
361  if (!RS || !shouldWarnAbout(OK, MK)
362  || isInMoveSafeContext(C.getLocationContext())) {
363  // Finalize changes made by the caller.
364  C.addTransition(State);
365  return;
366  }
367 
368  // Don't report it in case if any base region is already reported.
369  // But still generate a sink in case of UB.
370  // And still finalize changes made by the caller.
371  if (isAnyBaseRegionReported(State, Region)) {
372  if (misuseCausesCrash(MK)) {
373  C.generateSink(State, C.getPredecessor());
374  } else {
375  C.addTransition(State);
376  }
377  return;
378  }
379 
380  ExplodedNode *N = reportBug(Region, RD, C, MK);
381 
382  // If the program has already crashed on this path, don't bother.
383  if (N->isSink())
384  return;
385 
386  State = State->set<TrackedRegionMap>(Region, RegionState::getReported());
387  C.addTransition(State, N);
388 }
389 
390 ExplodedNode *MoveChecker::reportBug(const MemRegion *Region,
391  const CXXRecordDecl *RD, CheckerContext &C,
392  MisuseKind MK) const {
393  if (ExplodedNode *N = misuseCausesCrash(MK) ? C.generateErrorNode()
394  : C.generateNonFatalErrorNode()) {
395 
396  if (!BT)
397  BT.reset(new BugType(this, "Use-after-move",
398  "C++ move semantics"));
399 
400  // Uniqueing report to the same object.
401  PathDiagnosticLocation LocUsedForUniqueing;
402  const ExplodedNode *MoveNode = getMoveLocation(N, Region, C);
403 
404  if (const Stmt *MoveStmt = MoveNode->getStmtForDiagnostics())
405  LocUsedForUniqueing = PathDiagnosticLocation::createBegin(
406  MoveStmt, C.getSourceManager(), MoveNode->getLocationContext());
407 
408  // Creating the error message.
410  llvm::raw_svector_ostream OS(Str);
411  switch(MK) {
412  case MK_FunCall:
413  OS << "Method called on moved-from object";
414  explainObject(OS, Region, RD, MK);
415  break;
416  case MK_Copy:
417  OS << "Moved-from object";
418  explainObject(OS, Region, RD, MK);
419  OS << " is copied";
420  break;
421  case MK_Move:
422  OS << "Moved-from object";
423  explainObject(OS, Region, RD, MK);
424  OS << " is moved";
425  break;
426  case MK_Dereference:
427  OS << "Dereference of null smart pointer";
428  explainObject(OS, Region, RD, MK);
429  break;
430  }
431 
432  auto R = std::make_unique<PathSensitiveBugReport>(
433  *BT, OS.str(), N, LocUsedForUniqueing,
434  MoveNode->getLocationContext()->getDecl());
435  R->addVisitor(std::make_unique<MovedBugVisitor>(*this, Region, RD, MK));
436  C.emitReport(std::move(R));
437  return N;
438  }
439  return nullptr;
440 }
441 
442 void MoveChecker::checkPostCall(const CallEvent &Call,
443  CheckerContext &C) const {
444  const auto *AFC = dyn_cast<AnyFunctionCall>(&Call);
445  if (!AFC)
446  return;
447 
448  ProgramStateRef State = C.getState();
449  const auto MethodDecl = dyn_cast_or_null<CXXMethodDecl>(AFC->getDecl());
450  if (!MethodDecl)
451  return;
452 
453  // Check if an object became moved-from.
454  // Object can become moved from after a call to move assignment operator or
455  // move constructor .
456  const auto *ConstructorDecl = dyn_cast<CXXConstructorDecl>(MethodDecl);
457  if (ConstructorDecl && !ConstructorDecl->isMoveConstructor())
458  return;
459 
460  if (!ConstructorDecl && !MethodDecl->isMoveAssignmentOperator())
461  return;
462 
463  const auto ArgRegion = AFC->getArgSVal(0).getAsRegion();
464  if (!ArgRegion)
465  return;
466 
467  // Skip moving the object to itself.
468  const auto *CC = dyn_cast_or_null<CXXConstructorCall>(&Call);
469  if (CC && CC->getCXXThisVal().getAsRegion() == ArgRegion)
470  return;
471 
472  if (const auto *IC = dyn_cast<CXXInstanceCall>(AFC))
473  if (IC->getCXXThisVal().getAsRegion() == ArgRegion)
474  return;
475 
476  const MemRegion *BaseRegion = ArgRegion->getBaseRegion();
477  // Skip temp objects because of their short lifetime.
478  if (BaseRegion->getAs<CXXTempObjectRegion>() ||
479  AFC->getArgExpr(0)->isRValue())
480  return;
481  // If it has already been reported do not need to modify the state.
482 
483  if (State->get<TrackedRegionMap>(ArgRegion))
484  return;
485 
486  const CXXRecordDecl *RD = MethodDecl->getParent();
487  ObjectKind OK = classifyObject(ArgRegion, RD);
488  if (shouldBeTracked(OK)) {
489  // Mark object as moved-from.
490  State = State->set<TrackedRegionMap>(ArgRegion, RegionState::getMoved());
491  C.addTransition(State);
492  return;
493  }
494  assert(!C.isDifferent() && "Should not have made transitions on this path!");
495 }
496 
497 bool MoveChecker::isMoveSafeMethod(const CXXMethodDecl *MethodDec) const {
498  // We abandon the cases where bool/void/void* conversion happens.
499  if (const auto *ConversionDec =
500  dyn_cast_or_null<CXXConversionDecl>(MethodDec)) {
501  const Type *Tp = ConversionDec->getConversionType().getTypePtrOrNull();
502  if (!Tp)
503  return false;
504  if (Tp->isBooleanType() || Tp->isVoidType() || Tp->isVoidPointerType())
505  return true;
506  }
507  // Function call `empty` can be skipped.
508  return (MethodDec && MethodDec->getDeclName().isIdentifier() &&
509  (MethodDec->getName().lower() == "empty" ||
510  MethodDec->getName().lower() == "isempty"));
511 }
512 
513 bool MoveChecker::isStateResetMethod(const CXXMethodDecl *MethodDec) const {
514  if (!MethodDec)
515  return false;
516  if (MethodDec->hasAttr<ReinitializesAttr>())
517  return true;
518  if (MethodDec->getDeclName().isIdentifier()) {
519  std::string MethodName = MethodDec->getName().lower();
520  // TODO: Some of these methods (eg., resize) are not always resetting
521  // the state, so we should consider looking at the arguments.
522  if (MethodName == "assign" || MethodName == "clear" ||
523  MethodName == "destroy" || MethodName == "reset" ||
524  MethodName == "resize" || MethodName == "shrink")
525  return true;
526  }
527  return false;
528 }
529 
530 // Don't report an error inside a move related operation.
531 // We assume that the programmer knows what she does.
532 bool MoveChecker::isInMoveSafeContext(const LocationContext *LC) const {
533  do {
534  const auto *CtxDec = LC->getDecl();
535  auto *CtorDec = dyn_cast_or_null<CXXConstructorDecl>(CtxDec);
536  auto *DtorDec = dyn_cast_or_null<CXXDestructorDecl>(CtxDec);
537  auto *MethodDec = dyn_cast_or_null<CXXMethodDecl>(CtxDec);
538  if (DtorDec || (CtorDec && CtorDec->isCopyOrMoveConstructor()) ||
539  (MethodDec && MethodDec->isOverloadedOperator() &&
540  MethodDec->getOverloadedOperator() == OO_Equal) ||
541  isStateResetMethod(MethodDec) || isMoveSafeMethod(MethodDec))
542  return true;
543  } while ((LC = LC->getParent()));
544  return false;
545 }
546 
547 bool MoveChecker::belongsTo(const CXXRecordDecl *RD,
548  const llvm::StringSet<> &Set) const {
549  const IdentifierInfo *II = RD->getIdentifier();
550  return II && Set.count(II->getName());
551 }
552 
553 MoveChecker::ObjectKind
554 MoveChecker::classifyObject(const MemRegion *MR,
555  const CXXRecordDecl *RD) const {
556  // Local variables and local rvalue references are classified as "Local".
557  // For the purposes of this checker, we classify move-safe STL types
558  // as not-"STL" types, because that's how the checker treats them.
560  bool IsLocal =
561  MR && isa<VarRegion>(MR) && isa<StackSpaceRegion>(MR->getMemorySpace());
562 
563  if (!RD || !RD->getDeclContext()->isStdNamespace())
564  return { IsLocal, SK_NonStd };
565 
566  if (belongsTo(RD, StdSmartPtrClasses))
567  return { IsLocal, SK_SmartPtr };
568 
569  if (belongsTo(RD, StdSafeClasses))
570  return { IsLocal, SK_Safe };
571 
572  return { IsLocal, SK_Unsafe };
573 }
574 
575 void MoveChecker::explainObject(llvm::raw_ostream &OS, const MemRegion *MR,
576  const CXXRecordDecl *RD, MisuseKind MK) const {
577  // We may need a leading space every time we actually explain anything,
578  // and we never know if we are to explain anything until we try.
579  if (const auto DR =
580  dyn_cast_or_null<DeclRegion>(unwrapRValueReferenceIndirection(MR))) {
581  const auto *RegionDecl = cast<NamedDecl>(DR->getDecl());
582  OS << " '" << RegionDecl->getNameAsString() << "'";
583  }
584 
585  ObjectKind OK = classifyObject(MR, RD);
586  switch (OK.StdKind) {
587  case SK_NonStd:
588  case SK_Safe:
589  break;
590  case SK_SmartPtr:
591  if (MK != MK_Dereference)
592  break;
593 
594  // We only care about the type if it's a dereference.
595  LLVM_FALLTHROUGH;
596  case SK_Unsafe:
597  OS << " of type '" << RD->getQualifiedNameAsString() << "'";
598  break;
599  };
600 }
601 
602 void MoveChecker::checkPreCall(const CallEvent &Call, CheckerContext &C) const {
603  ProgramStateRef State = C.getState();
604 
605  // Remove the MemRegions from the map on which a ctor/dtor call or assignment
606  // happened.
607 
608  // Checking constructor calls.
609  if (const auto *CC = dyn_cast<CXXConstructorCall>(&Call)) {
610  State = removeFromState(State, CC->getCXXThisVal().getAsRegion());
611  auto CtorDec = CC->getDecl();
612  // Check for copying a moved-from object and report the bug.
613  if (CtorDec && CtorDec->isCopyOrMoveConstructor()) {
614  const MemRegion *ArgRegion = CC->getArgSVal(0).getAsRegion();
615  const CXXRecordDecl *RD = CtorDec->getParent();
616  MisuseKind MK = CtorDec->isMoveConstructor() ? MK_Move : MK_Copy;
617  modelUse(State, ArgRegion, RD, MK, C);
618  return;
619  }
620  }
621 
622  const auto IC = dyn_cast<CXXInstanceCall>(&Call);
623  if (!IC)
624  return;
625 
626  // Calling a destructor on a moved object is fine.
627  if (isa<CXXDestructorCall>(IC))
628  return;
629 
630  const MemRegion *ThisRegion = IC->getCXXThisVal().getAsRegion();
631  if (!ThisRegion)
632  return;
633 
634  // The remaining part is check only for method call on a moved-from object.
635  const auto MethodDecl = dyn_cast_or_null<CXXMethodDecl>(IC->getDecl());
636  if (!MethodDecl)
637  return;
638 
639  // We want to investigate the whole object, not only sub-object of a parent
640  // class in which the encountered method defined.
641  ThisRegion = ThisRegion->getMostDerivedObjectRegion();
642 
643  if (isStateResetMethod(MethodDecl)) {
644  State = removeFromState(State, ThisRegion);
645  C.addTransition(State);
646  return;
647  }
648 
649  if (isMoveSafeMethod(MethodDecl))
650  return;
651 
652  // Store class declaration as well, for bug reporting purposes.
653  const CXXRecordDecl *RD = MethodDecl->getParent();
654 
655  if (MethodDecl->isOverloadedOperator()) {
656  OverloadedOperatorKind OOK = MethodDecl->getOverloadedOperator();
657 
658  if (OOK == OO_Equal) {
659  // Remove the tracked object for every assignment operator, but report bug
660  // only for move or copy assignment's argument.
661  State = removeFromState(State, ThisRegion);
662 
663  if (MethodDecl->isCopyAssignmentOperator() ||
664  MethodDecl->isMoveAssignmentOperator()) {
665  const MemRegion *ArgRegion = IC->getArgSVal(0).getAsRegion();
666  MisuseKind MK =
667  MethodDecl->isMoveAssignmentOperator() ? MK_Move : MK_Copy;
668  modelUse(State, ArgRegion, RD, MK, C);
669  return;
670  }
671  C.addTransition(State);
672  return;
673  }
674 
675  if (OOK == OO_Star || OOK == OO_Arrow) {
676  modelUse(State, ThisRegion, RD, MK_Dereference, C);
677  return;
678  }
679  }
680 
681  modelUse(State, ThisRegion, RD, MK_FunCall, C);
682 }
683 
684 void MoveChecker::checkDeadSymbols(SymbolReaper &SymReaper,
685  CheckerContext &C) const {
686  ProgramStateRef State = C.getState();
687  TrackedRegionMapTy TrackedRegions = State->get<TrackedRegionMap>();
688  for (TrackedRegionMapTy::value_type E : TrackedRegions) {
689  const MemRegion *Region = E.first;
690  bool IsRegDead = !SymReaper.isLiveRegion(Region);
691 
692  // Remove the dead regions from the region map.
693  if (IsRegDead) {
694  State = State->remove<TrackedRegionMap>(Region);
695  }
696  }
697  C.addTransition(State);
698 }
699 
700 ProgramStateRef MoveChecker::checkRegionChanges(
701  ProgramStateRef State, const InvalidatedSymbols *Invalidated,
702  ArrayRef<const MemRegion *> RequestedRegions,
703  ArrayRef<const MemRegion *> InvalidatedRegions,
704  const LocationContext *LCtx, const CallEvent *Call) const {
705  if (Call) {
706  // Relax invalidation upon function calls: only invalidate parameters
707  // that are passed directly via non-const pointers or non-const references
708  // or rvalue references.
709  // In case of an InstanceCall don't invalidate the this-region since
710  // it is fully handled in checkPreCall and checkPostCall.
711  const MemRegion *ThisRegion = nullptr;
712  if (const auto *IC = dyn_cast<CXXInstanceCall>(Call))
713  ThisRegion = IC->getCXXThisVal().getAsRegion();
714 
715  // Requested ("explicit") regions are the regions passed into the call
716  // directly, but not all of them end up being invalidated.
717  // But when they do, they appear in the InvalidatedRegions array as well.
718  for (const auto *Region : RequestedRegions) {
719  if (ThisRegion != Region) {
720  if (llvm::find(InvalidatedRegions, Region) !=
721  std::end(InvalidatedRegions)) {
722  State = removeFromState(State, Region);
723  }
724  }
725  }
726  } else {
727  // For invalidations that aren't caused by calls, assume nothing. In
728  // particular, direct write into an object's field invalidates the status.
729  for (const auto *Region : InvalidatedRegions)
730  State = removeFromState(State, Region->getBaseRegion());
731  }
732 
733  return State;
734 }
735 
736 void MoveChecker::printState(raw_ostream &Out, ProgramStateRef State,
737  const char *NL, const char *Sep) const {
738 
739  TrackedRegionMapTy RS = State->get<TrackedRegionMap>();
740 
741  if (!RS.isEmpty()) {
742  Out << Sep << "Moved-from objects :" << NL;
743  for (auto I: RS) {
744  I.first->dumpToStream(Out);
745  if (I.second.isMoved())
746  Out << ": moved";
747  else
748  Out << ": moved and reported";
749  Out << NL;
750  }
751  }
752 }
753 void ento::registerMoveChecker(CheckerManager &mgr) {
754  MoveChecker *chk = mgr.registerChecker<MoveChecker>();
755  chk->setAggressiveness(
756  mgr.getAnalyzerOptions().getCheckerStringOption(chk, "WarnOn"), mgr);
757 }
758 
759 bool ento::shouldRegisterMoveChecker(const LangOptions &LO) {
760  return true;
761 }
MemRegion - The root abstract class for all memory regions.
Definition: MemRegion.h:94
bool operator==(CanQual< T > x, CanQual< U > y)
llvm::DenseSet< SymbolRef > InvalidatedSymbols
Definition: Store.h:51
Stmt - This represents one statement.
Definition: Stmt.h:66
IntrusiveRefCntPtr< const ProgramState > ProgramStateRef
The base class of the type hierarchy.
Definition: Type.h:1436
static ProgramStateRef removeFromState(ProgramStateRef State, const MemRegion *Region)
Represents a C++ constructor within a class.
Definition: DeclCXX.h:2352
Defines the clang::Expr interface and subclasses for C++ expressions.
IdentifierInfo * getIdentifier() const
Get the identifier that names this declaration, if there is one.
Definition: Decl.h:269
DeclarationName getDeclName() const
Get the actual, stored name of the declaration, which may be a special name.
Definition: Decl.h:297
One of these records is kept for each identifier that is lexed.
const SymExpr * SymbolRef
Definition: SymExpr.h:110
LineState State
Keeps track of the various options that can be enabled, which controls the dialect of C or C++ that i...
Definition: LangOptions.h:49
std::shared_ptr< PathDiagnosticPiece > PathDiagnosticPieceRef
const LocationContext * getParent() const
bool isMovedFrom(ProgramStateRef State, const MemRegion *Region)
Returns true if the object is known to have been recently std::moved.
bool hasAttr() const
Definition: DeclBase.h:542
Represents a non-static C++ member function call, no matter how it is written.
Definition: CallEvent.h:638
DeclContext * getDeclContext()
Definition: DeclBase.h:438
virtual SVal getCXXThisVal() const
Returns the value of the implicit &#39;this&#39; object.
Definition: CallEvent.cpp:712
static bool isAnyBaseRegionReported(ProgramStateRef State, const MemRegion *Region)
bool isIdentifier() const
Predicate functions for querying what type of name this is.
DeclContext * getParent()
getParent - Returns the containing DeclContext.
Definition: DeclBase.h:1779
ReturnStmt - This represents a return, optionally of an expression: return; return 4;...
Definition: Stmt.h:2610
bool isVoidPointerType() const
Definition: Type.cpp:521
static const MemRegion * unwrapRValueReferenceIndirection(const MemRegion *MR)
static PathDiagnosticLocation createBegin(const Decl *D, const SourceManager &SM)
Create a location for the beginning of the declaration.
#define false
Definition: stdbool.h:17
Kind
#define REGISTER_MAP_WITH_PROGRAMSTATE(Name, Key, Value)
Declares an immutable map of type NameTy, suitable for placement into the ProgramState.
Represents a static or instance method of a struct/union/class.
Definition: DeclCXX.h:1892
bool isStdNamespace() const
Definition: DeclBase.cpp:1073
StringRef getName() const
Return the actual identifier string.
Dataflow Directional Tag Classes.
OverloadedOperatorKind
Enumeration specifying the different kinds of C++ overloaded operators.
Definition: OperatorKinds.h:21
bool isBooleanType() const
Definition: Type.h:6767
const Decl * getDecl() const
Indicates that the tracking object is a descendant of a referenced-counted OSObject, used in the Darwin kernel.
X
Add a minimal nested name specifier fixit hint to allow lookup of a tag name from an outer enclosing ...
Definition: SemaDecl.cpp:14652
Represents a C++ struct/union/class.
Definition: DeclCXX.h:255
bool isVoidType() const
Definition: Type.h:6650
StringRef getName() const
Get the name of identifier for this declaration as a StringRef.
Definition: Decl.h:275
std::string getQualifiedNameAsString() const
Definition: Decl.cpp:1548