clang  14.0.0git
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/Attr.h"
16 #include "clang/AST/ExprCXX.h"
24 #include "llvm/ADT/StringSet.h"
25 
26 using namespace clang;
27 using namespace ento;
28 
29 namespace {
30 struct RegionState {
31 private:
32  enum Kind { Moved, Reported } K;
33  RegionState(Kind InK) : K(InK) {}
34 
35 public:
36  bool isReported() const { return K == Reported; }
37  bool isMoved() const { return K == Moved; }
38 
39  static RegionState getReported() { return RegionState(Reported); }
40  static RegionState getMoved() { return RegionState(Moved); }
41 
42  bool operator==(const RegionState &X) const { return K == X.K; }
43  void Profile(llvm::FoldingSetNodeID &ID) const { ID.AddInteger(K); }
44 };
45 } // end of anonymous namespace
46 
47 namespace {
48 class MoveChecker
49  : public Checker<check::PreCall, check::PostCall,
50  check::DeadSymbols, check::RegionChanges> {
51 public:
52  void checkEndFunction(const ReturnStmt *RS, CheckerContext &C) const;
53  void checkPreCall(const CallEvent &MC, CheckerContext &C) const;
54  void checkPostCall(const CallEvent &MC, CheckerContext &C) const;
55  void checkDeadSymbols(SymbolReaper &SR, CheckerContext &C) const;
57  checkRegionChanges(ProgramStateRef State,
58  const InvalidatedSymbols *Invalidated,
59  ArrayRef<const MemRegion *> RequestedRegions,
60  ArrayRef<const MemRegion *> InvalidatedRegions,
61  const LocationContext *LCtx, const CallEvent *Call) const;
62  void printState(raw_ostream &Out, ProgramStateRef State,
63  const char *NL, const char *Sep) const override;
64 
65 private:
66  enum MisuseKind { MK_FunCall, MK_Copy, MK_Move, MK_Dereference };
67  enum StdObjectKind { SK_NonStd, SK_Unsafe, SK_Safe, SK_SmartPtr };
68 
69  enum AggressivenessKind { // In any case, don't warn after a reset.
70  AK_Invalid = -1,
71  AK_KnownsOnly = 0, // Warn only about known move-unsafe classes.
72  AK_KnownsAndLocals = 1, // Also warn about all local objects.
73  AK_All = 2, // Warn on any use-after-move.
74  AK_NumKinds = AK_All
75  };
76 
77  static bool misuseCausesCrash(MisuseKind MK) {
78  return MK == MK_Dereference;
79  }
80 
81  struct ObjectKind {
82  // Is this a local variable or a local rvalue reference?
83  bool IsLocal;
84  // Is this an STL object? If so, of what kind?
85  StdObjectKind StdKind;
86  };
87 
88  // STL smart pointers are automatically re-initialized to null when moved
89  // from. So we can't warn on many methods, but we can warn when it is
90  // dereferenced, which is UB even if the resulting lvalue never gets read.
91  const llvm::StringSet<> StdSmartPtrClasses = {
92  "shared_ptr",
93  "unique_ptr",
94  "weak_ptr",
95  };
96 
97  // Not all of these are entirely move-safe, but they do provide *some*
98  // guarantees, and it means that somebody is using them after move
99  // in a valid manner.
100  // TODO: We can still try to identify *unsafe* use after move,
101  // like we did with smart pointers.
102  const llvm::StringSet<> StdSafeClasses = {
103  "basic_filebuf",
104  "basic_ios",
105  "future",
106  "optional",
107  "packaged_task",
108  "promise",
109  "shared_future",
110  "shared_lock",
111  "thread",
112  "unique_lock",
113  };
114 
115  // Should we bother tracking the state of the object?
116  bool shouldBeTracked(ObjectKind OK) const {
117  // In non-aggressive mode, only warn on use-after-move of local variables
118  // (or local rvalue references) and of STL objects. The former is possible
119  // because local variables (or local rvalue references) are not tempting
120  // their user to re-use the storage. The latter is possible because STL
121  // objects are known to end up in a valid but unspecified state after the
122  // move and their state-reset methods are also known, which allows us to
123  // predict precisely when use-after-move is invalid.
124  // Some STL objects are known to conform to additional contracts after move,
125  // so they are not tracked. However, smart pointers specifically are tracked
126  // because we can perform extra checking over them.
127  // In aggressive mode, warn on any use-after-move because the user has
128  // intentionally asked us to completely eliminate use-after-move
129  // in his code.
130  return (Aggressiveness == AK_All) ||
131  (Aggressiveness >= AK_KnownsAndLocals && OK.IsLocal) ||
132  OK.StdKind == SK_Unsafe || OK.StdKind == SK_SmartPtr;
133  }
134 
135  // Some objects only suffer from some kinds of misuses, but we need to track
136  // them anyway because we cannot know in advance what misuse will we find.
137  bool shouldWarnAbout(ObjectKind OK, MisuseKind MK) const {
138  // Additionally, only warn on smart pointers when they are dereferenced (or
139  // local or we are aggressive).
140  return shouldBeTracked(OK) &&
141  ((Aggressiveness == AK_All) ||
142  (Aggressiveness >= AK_KnownsAndLocals && OK.IsLocal) ||
143  OK.StdKind != SK_SmartPtr || MK == MK_Dereference);
144  }
145 
146  // Obtains ObjectKind of an object. Because class declaration cannot always
147  // be easily obtained from the memory region, it is supplied separately.
148  ObjectKind classifyObject(const MemRegion *MR, const CXXRecordDecl *RD) const;
149 
150  // Classifies the object and dumps a user-friendly description string to
151  // the stream.
152  void explainObject(llvm::raw_ostream &OS, const MemRegion *MR,
153  const CXXRecordDecl *RD, MisuseKind MK) const;
154 
155  bool belongsTo(const CXXRecordDecl *RD, const llvm::StringSet<> &Set) const;
156 
157  class MovedBugVisitor : public BugReporterVisitor {
158  public:
159  MovedBugVisitor(const MoveChecker &Chk, const MemRegion *R,
160  const CXXRecordDecl *RD, MisuseKind MK)
161  : Chk(Chk), Region(R), RD(RD), MK(MK), Found(false) {}
162 
163  void Profile(llvm::FoldingSetNodeID &ID) const override {
164  static int X = 0;
165  ID.AddPointer(&X);
166  ID.AddPointer(Region);
167  // Don't add RD because it's, in theory, uniquely determined by
168  // the region. In practice though, it's not always possible to obtain
169  // the declaration directly from the region, that's why we store it
170  // in the first place.
171  }
172 
173  PathDiagnosticPieceRef VisitNode(const ExplodedNode *N,
174  BugReporterContext &BRC,
175  PathSensitiveBugReport &BR) override;
176 
177  private:
178  const MoveChecker &Chk;
179  // The tracked region.
180  const MemRegion *Region;
181  // The class of the tracked object.
182  const CXXRecordDecl *RD;
183  // How exactly the object was misused.
184  const MisuseKind MK;
185  bool Found;
186  };
187 
188  AggressivenessKind Aggressiveness;
189 
190 public:
191  void setAggressiveness(StringRef Str, CheckerManager &Mgr) {
192  Aggressiveness =
193  llvm::StringSwitch<AggressivenessKind>(Str)
194  .Case("KnownsOnly", AK_KnownsOnly)
195  .Case("KnownsAndLocals", AK_KnownsAndLocals)
196  .Case("All", AK_All)
197  .Default(AK_Invalid);
198 
199  if (Aggressiveness == AK_Invalid)
200  Mgr.reportInvalidCheckerOptionValue(this, "WarnOn",
201  "either \"KnownsOnly\", \"KnownsAndLocals\" or \"All\" string value");
202  };
203 
204 private:
205  BugType BT{this, "Use-after-move", categories::CXXMoveSemantics};
206 
207  // Check if the given form of potential misuse of a given object
208  // should be reported. If so, get it reported. The callback from which
209  // this function was called should immediately return after the call
210  // because this function adds one or two transitions.
211  void modelUse(ProgramStateRef State, const MemRegion *Region,
212  const CXXRecordDecl *RD, MisuseKind MK,
213  CheckerContext &C) const;
214 
215  // Returns the exploded node against which the report was emitted.
216  // The caller *must* add any further transitions against this node.
217  ExplodedNode *reportBug(const MemRegion *Region, const CXXRecordDecl *RD,
218  CheckerContext &C, MisuseKind MK) const;
219 
220  bool isInMoveSafeContext(const LocationContext *LC) const;
221  bool isStateResetMethod(const CXXMethodDecl *MethodDec) const;
222  bool isMoveSafeMethod(const CXXMethodDecl *MethodDec) const;
223  const ExplodedNode *getMoveLocation(const ExplodedNode *N,
224  const MemRegion *Region,
225  CheckerContext &C) const;
226 };
227 } // end anonymous namespace
228 
229 REGISTER_MAP_WITH_PROGRAMSTATE(TrackedRegionMap, const MemRegion *, RegionState)
230 
231 // Define the inter-checker API.
232 namespace clang {
233 namespace ento {
234 namespace move {
236  const RegionState *RS = State->get<TrackedRegionMap>(Region);
237  return RS && (RS->isMoved() || RS->isReported());
238 }
239 } // namespace move
240 } // namespace ento
241 } // namespace clang
242 
243 // If a region is removed all of the subregions needs to be removed too.
245  const MemRegion *Region) {
246  if (!Region)
247  return State;
248  for (auto &E : State->get<TrackedRegionMap>()) {
249  if (E.first->isSubRegionOf(Region))
250  State = State->remove<TrackedRegionMap>(E.first);
251  }
252  return State;
253 }
254 
256  const MemRegion *Region) {
257  for (auto &E : State->get<TrackedRegionMap>()) {
258  if (Region->isSubRegionOf(E.first) && E.second.isReported())
259  return true;
260  }
261  return false;
262 }
263 
264 static const MemRegion *unwrapRValueReferenceIndirection(const MemRegion *MR) {
265  if (const auto *SR = dyn_cast_or_null<SymbolicRegion>(MR)) {
266  SymbolRef Sym = SR->getSymbol();
267  if (Sym->getType()->isRValueReferenceType())
268  if (const MemRegion *OriginMR = Sym->getOriginRegion())
269  return OriginMR;
270  }
271  return MR;
272 }
273 
275 MoveChecker::MovedBugVisitor::VisitNode(const ExplodedNode *N,
276  BugReporterContext &BRC,
277  PathSensitiveBugReport &BR) {
278  // We need only the last move of the reported object's region.
279  // The visitor walks the ExplodedGraph backwards.
280  if (Found)
281  return nullptr;
282  ProgramStateRef State = N->getState();
283  ProgramStateRef StatePrev = N->getFirstPred()->getState();
284  const RegionState *TrackedObject = State->get<TrackedRegionMap>(Region);
285  const RegionState *TrackedObjectPrev =
286  StatePrev->get<TrackedRegionMap>(Region);
287  if (!TrackedObject)
288  return nullptr;
289  if (TrackedObjectPrev && TrackedObject)
290  return nullptr;
291 
292  // Retrieve the associated statement.
293  const Stmt *S = N->getStmtForDiagnostics();
294  if (!S)
295  return nullptr;
296  Found = true;
297 
298  SmallString<128> Str;
299  llvm::raw_svector_ostream OS(Str);
300 
301  ObjectKind OK = Chk.classifyObject(Region, RD);
302  switch (OK.StdKind) {
303  case SK_SmartPtr:
304  if (MK == MK_Dereference) {
305  OS << "Smart pointer";
306  Chk.explainObject(OS, Region, RD, MK);
307  OS << " is reset to null when moved from";
308  break;
309  }
310 
311  // If it's not a dereference, we don't care if it was reset to null
312  // or that it is even a smart pointer.
313  LLVM_FALLTHROUGH;
314  case SK_NonStd:
315  case SK_Safe:
316  OS << "Object";
317  Chk.explainObject(OS, Region, RD, MK);
318  OS << " is moved";
319  break;
320  case SK_Unsafe:
321  OS << "Object";
322  Chk.explainObject(OS, Region, RD, MK);
323  OS << " is left in a valid but unspecified state after move";
324  break;
325  }
326 
327  // Generate the extra diagnostic.
328  PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
329  N->getLocationContext());
330  return std::make_shared<PathDiagnosticEventPiece>(Pos, OS.str(), true);
331 }
332 
333 const ExplodedNode *MoveChecker::getMoveLocation(const ExplodedNode *N,
334  const MemRegion *Region,
335  CheckerContext &C) const {
336  // Walk the ExplodedGraph backwards and find the first node that referred to
337  // the tracked region.
338  const ExplodedNode *MoveNode = N;
339 
340  while (N) {
341  ProgramStateRef State = N->getState();
342  if (!State->get<TrackedRegionMap>(Region))
343  break;
344  MoveNode = N;
345  N = N->pred_empty() ? nullptr : *(N->pred_begin());
346  }
347  return MoveNode;
348 }
349 
350 void MoveChecker::modelUse(ProgramStateRef State, const MemRegion *Region,
351  const CXXRecordDecl *RD, MisuseKind MK,
352  CheckerContext &C) const {
353  assert(!C.isDifferent() && "No transitions should have been made by now");
354  const RegionState *RS = State->get<TrackedRegionMap>(Region);
355  ObjectKind OK = classifyObject(Region, RD);
356 
357  // Just in case: if it's not a smart pointer but it does have operator *,
358  // we shouldn't call the bug a dereference.
359  if (MK == MK_Dereference && OK.StdKind != SK_SmartPtr)
360  MK = MK_FunCall;
361 
362  if (!RS || !shouldWarnAbout(OK, MK)
363  || isInMoveSafeContext(C.getLocationContext())) {
364  // Finalize changes made by the caller.
365  C.addTransition(State);
366  return;
367  }
368 
369  // Don't report it in case if any base region is already reported.
370  // But still generate a sink in case of UB.
371  // And still finalize changes made by the caller.
372  if (isAnyBaseRegionReported(State, Region)) {
373  if (misuseCausesCrash(MK)) {
374  C.generateSink(State, C.getPredecessor());
375  } else {
376  C.addTransition(State);
377  }
378  return;
379  }
380 
381  ExplodedNode *N = reportBug(Region, RD, C, MK);
382 
383  // If the program has already crashed on this path, don't bother.
384  if (N->isSink())
385  return;
386 
387  State = State->set<TrackedRegionMap>(Region, RegionState::getReported());
388  C.addTransition(State, N);
389 }
390 
391 ExplodedNode *MoveChecker::reportBug(const MemRegion *Region,
392  const CXXRecordDecl *RD, CheckerContext &C,
393  MisuseKind MK) const {
394  if (ExplodedNode *N = misuseCausesCrash(MK) ? C.generateErrorNode()
395  : C.generateNonFatalErrorNode()) {
396  // Uniqueing report to the same object.
397  PathDiagnosticLocation LocUsedForUniqueing;
398  const ExplodedNode *MoveNode = getMoveLocation(N, Region, C);
399 
400  if (const Stmt *MoveStmt = MoveNode->getStmtForDiagnostics())
401  LocUsedForUniqueing = PathDiagnosticLocation::createBegin(
402  MoveStmt, C.getSourceManager(), MoveNode->getLocationContext());
403 
404  // Creating the error message.
406  llvm::raw_svector_ostream OS(Str);
407  switch(MK) {
408  case MK_FunCall:
409  OS << "Method called on moved-from object";
410  explainObject(OS, Region, RD, MK);
411  break;
412  case MK_Copy:
413  OS << "Moved-from object";
414  explainObject(OS, Region, RD, MK);
415  OS << " is copied";
416  break;
417  case MK_Move:
418  OS << "Moved-from object";
419  explainObject(OS, Region, RD, MK);
420  OS << " is moved";
421  break;
422  case MK_Dereference:
423  OS << "Dereference of null smart pointer";
424  explainObject(OS, Region, RD, MK);
425  break;
426  }
427 
428  auto R = std::make_unique<PathSensitiveBugReport>(
429  BT, OS.str(), N, LocUsedForUniqueing,
430  MoveNode->getLocationContext()->getDecl());
431  R->addVisitor(std::make_unique<MovedBugVisitor>(*this, Region, RD, MK));
432  C.emitReport(std::move(R));
433  return N;
434  }
435  return nullptr;
436 }
437 
438 void MoveChecker::checkPostCall(const CallEvent &Call,
439  CheckerContext &C) const {
440  const auto *AFC = dyn_cast<AnyFunctionCall>(&Call);
441  if (!AFC)
442  return;
443 
444  ProgramStateRef State = C.getState();
445  const auto MethodDecl = dyn_cast_or_null<CXXMethodDecl>(AFC->getDecl());
446  if (!MethodDecl)
447  return;
448 
449  // Check if an object became moved-from.
450  // Object can become moved from after a call to move assignment operator or
451  // move constructor .
452  const auto *ConstructorDecl = dyn_cast<CXXConstructorDecl>(MethodDecl);
453  if (ConstructorDecl && !ConstructorDecl->isMoveConstructor())
454  return;
455 
456  if (!ConstructorDecl && !MethodDecl->isMoveAssignmentOperator())
457  return;
458 
459  const auto ArgRegion = AFC->getArgSVal(0).getAsRegion();
460  if (!ArgRegion)
461  return;
462 
463  // Skip moving the object to itself.
464  const auto *CC = dyn_cast_or_null<CXXConstructorCall>(&Call);
465  if (CC && CC->getCXXThisVal().getAsRegion() == ArgRegion)
466  return;
467 
468  if (const auto *IC = dyn_cast<CXXInstanceCall>(AFC))
469  if (IC->getCXXThisVal().getAsRegion() == ArgRegion)
470  return;
471 
472  const MemRegion *BaseRegion = ArgRegion->getBaseRegion();
473  // Skip temp objects because of their short lifetime.
474  if (BaseRegion->getAs<CXXTempObjectRegion>() ||
475  AFC->getArgExpr(0)->isPRValue())
476  return;
477  // If it has already been reported do not need to modify the state.
478 
479  if (State->get<TrackedRegionMap>(ArgRegion))
480  return;
481 
482  const CXXRecordDecl *RD = MethodDecl->getParent();
483  ObjectKind OK = classifyObject(ArgRegion, RD);
484  if (shouldBeTracked(OK)) {
485  // Mark object as moved-from.
486  State = State->set<TrackedRegionMap>(ArgRegion, RegionState::getMoved());
487  C.addTransition(State);
488  return;
489  }
490  assert(!C.isDifferent() && "Should not have made transitions on this path!");
491 }
492 
493 bool MoveChecker::isMoveSafeMethod(const CXXMethodDecl *MethodDec) const {
494  // We abandon the cases where bool/void/void* conversion happens.
495  if (const auto *ConversionDec =
496  dyn_cast_or_null<CXXConversionDecl>(MethodDec)) {
497  const Type *Tp = ConversionDec->getConversionType().getTypePtrOrNull();
498  if (!Tp)
499  return false;
500  if (Tp->isBooleanType() || Tp->isVoidType() || Tp->isVoidPointerType())
501  return true;
502  }
503  // Function call `empty` can be skipped.
504  return (MethodDec && MethodDec->getDeclName().isIdentifier() &&
505  (MethodDec->getName().lower() == "empty" ||
506  MethodDec->getName().lower() == "isempty"));
507 }
508 
509 bool MoveChecker::isStateResetMethod(const CXXMethodDecl *MethodDec) const {
510  if (!MethodDec)
511  return false;
512  if (MethodDec->hasAttr<ReinitializesAttr>())
513  return true;
514  if (MethodDec->getDeclName().isIdentifier()) {
515  std::string MethodName = MethodDec->getName().lower();
516  // TODO: Some of these methods (eg., resize) are not always resetting
517  // the state, so we should consider looking at the arguments.
518  if (MethodName == "assign" || MethodName == "clear" ||
519  MethodName == "destroy" || MethodName == "reset" ||
520  MethodName == "resize" || MethodName == "shrink")
521  return true;
522  }
523  return false;
524 }
525 
526 // Don't report an error inside a move related operation.
527 // We assume that the programmer knows what she does.
528 bool MoveChecker::isInMoveSafeContext(const LocationContext *LC) const {
529  do {
530  const auto *CtxDec = LC->getDecl();
531  auto *CtorDec = dyn_cast_or_null<CXXConstructorDecl>(CtxDec);
532  auto *DtorDec = dyn_cast_or_null<CXXDestructorDecl>(CtxDec);
533  auto *MethodDec = dyn_cast_or_null<CXXMethodDecl>(CtxDec);
534  if (DtorDec || (CtorDec && CtorDec->isCopyOrMoveConstructor()) ||
535  (MethodDec && MethodDec->isOverloadedOperator() &&
536  MethodDec->getOverloadedOperator() == OO_Equal) ||
537  isStateResetMethod(MethodDec) || isMoveSafeMethod(MethodDec))
538  return true;
539  } while ((LC = LC->getParent()));
540  return false;
541 }
542 
543 bool MoveChecker::belongsTo(const CXXRecordDecl *RD,
544  const llvm::StringSet<> &Set) const {
545  const IdentifierInfo *II = RD->getIdentifier();
546  return II && Set.count(II->getName());
547 }
548 
549 MoveChecker::ObjectKind
550 MoveChecker::classifyObject(const MemRegion *MR,
551  const CXXRecordDecl *RD) const {
552  // Local variables and local rvalue references are classified as "Local".
553  // For the purposes of this checker, we classify move-safe STL types
554  // as not-"STL" types, because that's how the checker treats them.
556  bool IsLocal = isa_and_nonnull<VarRegion>(MR) &&
557  isa<StackSpaceRegion>(MR->getMemorySpace());
558 
559  if (!RD || !RD->getDeclContext()->isStdNamespace())
560  return { IsLocal, SK_NonStd };
561 
562  if (belongsTo(RD, StdSmartPtrClasses))
563  return { IsLocal, SK_SmartPtr };
564 
565  if (belongsTo(RD, StdSafeClasses))
566  return { IsLocal, SK_Safe };
567 
568  return { IsLocal, SK_Unsafe };
569 }
570 
571 void MoveChecker::explainObject(llvm::raw_ostream &OS, const MemRegion *MR,
572  const CXXRecordDecl *RD, MisuseKind MK) const {
573  // We may need a leading space every time we actually explain anything,
574  // and we never know if we are to explain anything until we try.
575  if (const auto DR =
576  dyn_cast_or_null<DeclRegion>(unwrapRValueReferenceIndirection(MR))) {
577  const auto *RegionDecl = cast<NamedDecl>(DR->getDecl());
578  OS << " '" << RegionDecl->getDeclName() << "'";
579  }
580 
581  ObjectKind OK = classifyObject(MR, RD);
582  switch (OK.StdKind) {
583  case SK_NonStd:
584  case SK_Safe:
585  break;
586  case SK_SmartPtr:
587  if (MK != MK_Dereference)
588  break;
589 
590  // We only care about the type if it's a dereference.
591  LLVM_FALLTHROUGH;
592  case SK_Unsafe:
593  OS << " of type '" << RD->getQualifiedNameAsString() << "'";
594  break;
595  };
596 }
597 
598 void MoveChecker::checkPreCall(const CallEvent &Call, CheckerContext &C) const {
599  ProgramStateRef State = C.getState();
600 
601  // Remove the MemRegions from the map on which a ctor/dtor call or assignment
602  // happened.
603 
604  // Checking constructor calls.
605  if (const auto *CC = dyn_cast<CXXConstructorCall>(&Call)) {
606  State = removeFromState(State, CC->getCXXThisVal().getAsRegion());
607  auto CtorDec = CC->getDecl();
608  // Check for copying a moved-from object and report the bug.
609  if (CtorDec && CtorDec->isCopyOrMoveConstructor()) {
610  const MemRegion *ArgRegion = CC->getArgSVal(0).getAsRegion();
611  const CXXRecordDecl *RD = CtorDec->getParent();
612  MisuseKind MK = CtorDec->isMoveConstructor() ? MK_Move : MK_Copy;
613  modelUse(State, ArgRegion, RD, MK, C);
614  return;
615  }
616  }
617 
618  const auto IC = dyn_cast<CXXInstanceCall>(&Call);
619  if (!IC)
620  return;
621 
622  // Calling a destructor on a moved object is fine.
623  if (isa<CXXDestructorCall>(IC))
624  return;
625 
626  const MemRegion *ThisRegion = IC->getCXXThisVal().getAsRegion();
627  if (!ThisRegion)
628  return;
629 
630  // The remaining part is check only for method call on a moved-from object.
631  const auto MethodDecl = dyn_cast_or_null<CXXMethodDecl>(IC->getDecl());
632  if (!MethodDecl)
633  return;
634 
635  // We want to investigate the whole object, not only sub-object of a parent
636  // class in which the encountered method defined.
637  ThisRegion = ThisRegion->getMostDerivedObjectRegion();
638 
639  if (isStateResetMethod(MethodDecl)) {
640  State = removeFromState(State, ThisRegion);
641  C.addTransition(State);
642  return;
643  }
644 
645  if (isMoveSafeMethod(MethodDecl))
646  return;
647 
648  // Store class declaration as well, for bug reporting purposes.
649  const CXXRecordDecl *RD = MethodDecl->getParent();
650 
651  if (MethodDecl->isOverloadedOperator()) {
652  OverloadedOperatorKind OOK = MethodDecl->getOverloadedOperator();
653 
654  if (OOK == OO_Equal) {
655  // Remove the tracked object for every assignment operator, but report bug
656  // only for move or copy assignment's argument.
657  State = removeFromState(State, ThisRegion);
658 
659  if (MethodDecl->isCopyAssignmentOperator() ||
660  MethodDecl->isMoveAssignmentOperator()) {
661  const MemRegion *ArgRegion = IC->getArgSVal(0).getAsRegion();
662  MisuseKind MK =
663  MethodDecl->isMoveAssignmentOperator() ? MK_Move : MK_Copy;
664  modelUse(State, ArgRegion, RD, MK, C);
665  return;
666  }
667  C.addTransition(State);
668  return;
669  }
670 
671  if (OOK == OO_Star || OOK == OO_Arrow) {
672  modelUse(State, ThisRegion, RD, MK_Dereference, C);
673  return;
674  }
675  }
676 
677  modelUse(State, ThisRegion, RD, MK_FunCall, C);
678 }
679 
680 void MoveChecker::checkDeadSymbols(SymbolReaper &SymReaper,
681  CheckerContext &C) const {
682  ProgramStateRef State = C.getState();
683  TrackedRegionMapTy TrackedRegions = State->get<TrackedRegionMap>();
684  for (auto E : TrackedRegions) {
685  const MemRegion *Region = E.first;
686  bool IsRegDead = !SymReaper.isLiveRegion(Region);
687 
688  // Remove the dead regions from the region map.
689  if (IsRegDead) {
690  State = State->remove<TrackedRegionMap>(Region);
691  }
692  }
693  C.addTransition(State);
694 }
695 
696 ProgramStateRef MoveChecker::checkRegionChanges(
697  ProgramStateRef State, const InvalidatedSymbols *Invalidated,
698  ArrayRef<const MemRegion *> RequestedRegions,
699  ArrayRef<const MemRegion *> InvalidatedRegions,
700  const LocationContext *LCtx, const CallEvent *Call) const {
701  if (Call) {
702  // Relax invalidation upon function calls: only invalidate parameters
703  // that are passed directly via non-const pointers or non-const references
704  // or rvalue references.
705  // In case of an InstanceCall don't invalidate the this-region since
706  // it is fully handled in checkPreCall and checkPostCall.
707  const MemRegion *ThisRegion = nullptr;
708  if (const auto *IC = dyn_cast<CXXInstanceCall>(Call))
709  ThisRegion = IC->getCXXThisVal().getAsRegion();
710 
711  // Requested ("explicit") regions are the regions passed into the call
712  // directly, but not all of them end up being invalidated.
713  // But when they do, they appear in the InvalidatedRegions array as well.
714  for (const auto *Region : RequestedRegions) {
715  if (ThisRegion != Region &&
716  llvm::is_contained(InvalidatedRegions, Region))
717  State = removeFromState(State, Region);
718  }
719  } else {
720  // For invalidations that aren't caused by calls, assume nothing. In
721  // particular, direct write into an object's field invalidates the status.
722  for (const auto *Region : InvalidatedRegions)
723  State = removeFromState(State, Region->getBaseRegion());
724  }
725 
726  return State;
727 }
728 
729 void MoveChecker::printState(raw_ostream &Out, ProgramStateRef State,
730  const char *NL, const char *Sep) const {
731 
732  TrackedRegionMapTy RS = State->get<TrackedRegionMap>();
733 
734  if (!RS.isEmpty()) {
735  Out << Sep << "Moved-from objects :" << NL;
736  for (auto I: RS) {
737  I.first->dumpToStream(Out);
738  if (I.second.isMoved())
739  Out << ": moved";
740  else
741  Out << ": moved and reported";
742  Out << NL;
743  }
744  }
745 }
746 void ento::registerMoveChecker(CheckerManager &mgr) {
747  MoveChecker *chk = mgr.registerChecker<MoveChecker>();
748  chk->setAggressiveness(
749  mgr.getAnalyzerOptions().getCheckerStringOption(chk, "WarnOn"), mgr);
750 }
751 
752 bool ento::shouldRegisterMoveChecker(const CheckerManager &mgr) {
753  return true;
754 }
clang::LocationContext
It wraps the AnalysisDeclContext to represent both the call stack with the help of StackFrameContext ...
Definition: AnalysisDeclContext.h:215
removeFromState
static ProgramStateRef removeFromState(ProgramStateRef State, const MemRegion *Region)
Definition: MoveChecker.cpp:244
string
string(SUBSTRING ${CMAKE_CURRENT_BINARY_DIR} 0 ${PATH_LIB_START} PATH_HEAD) string(SUBSTRING $
Definition: CMakeLists.txt:22
clang::Type::isVoidPointerType
bool isVoidPointerType() const
Definition: Type.cpp:589
clang::Decl::hasAttr
bool hasAttr() const
Definition: DeclBase.h:547
clang::ento::PathDiagnosticPieceRef
std::shared_ptr< PathDiagnosticPiece > PathDiagnosticPieceRef
Definition: PathDiagnostic.h:494
clang::ento::categories::CXXMoveSemantics
const char *const CXXMoveSemantics
Definition: CommonBugCategories.cpp:23
clang::ento::ProgramStateRef
IntrusiveRefCntPtr< const ProgramState > ProgramStateRef
Definition: ProgramState_Fwd.h:37
Attr.h
AttributeLangSupport::C
@ C
Definition: SemaDeclAttr.cpp:54
clang::FunctionDecl::isOverloadedOperator
bool isOverloadedOperator() const
Whether this function declaration represents an C++ overloaded operator, e.g., "operator+".
Definition: Decl.h:2625
clang::ento::SymbolRef
const SymExpr * SymbolRef
Definition: SymExpr.h:110
clang::Type::isVoidType
bool isVoidType() const
Definition: Type.h:6959
clang::tooling::X
static ToolExecutorPluginRegistry::Add< AllTUsToolExecutorPlugin > X("all-TUs", "Runs FrontendActions on all TUs in the compilation database. " "Tool results are stored in memory.")
clang::Type
The base class of the type hierarchy.
Definition: Type.h:1490
CallEvent.h
clang::ento::MemRegion
MemRegion - The root abstract class for all memory regions.
Definition: MemRegion.h:94
REGISTER_MAP_WITH_PROGRAMSTATE
#define REGISTER_MAP_WITH_PROGRAMSTATE(Name, Key, Value)
Declares an immutable map of type NameTy, suitable for placement into the ProgramState.
Definition: ProgramStateTrait.h:84
BuiltinCheckerRegistration.h
isAnyBaseRegionReported
static bool isAnyBaseRegionReported(ProgramStateRef State, const MemRegion *Region)
Definition: MoveChecker.cpp:255
CheckerManager.h
DriverDiagnostic.h
clang::DeclContext::isStdNamespace
bool isStdNamespace() const
Definition: DeclBase.cpp:1126
llvm::SmallString< 128 >
ExprCXX.h
clang::FunctionDecl::getOverloadedOperator
OverloadedOperatorKind getOverloadedOperator() const
getOverloadedOperator - Which C++ overloaded operator this function represents, if any.
Definition: Decl.cpp:3652
unwrapRValueReferenceIndirection
static const MemRegion * unwrapRValueReferenceIndirection(const MemRegion *MR)
Definition: MoveChecker.cpp:264
clang::OverloadedOperatorKind
OverloadedOperatorKind
Enumeration specifying the different kinds of C++ overloaded operators.
Definition: OperatorKinds.h:21
clang::LocationContext::getParent
const LocationContext * getParent() const
Definition: AnalysisDeclContext.h:243
clang::CXXRecordDecl
Represents a C++ struct/union/class.
Definition: DeclCXX.h:255
false
#define false
Definition: stdbool.h:17
BugType.h
clang::NamedDecl::getIdentifier
IdentifierInfo * getIdentifier() const
Get the identifier that names this declaration, if there is one.
Definition: Decl.h:270
clang::DeclContext::getParent
DeclContext * getParent()
getParent - Returns the containing DeclContext.
Definition: DeclBase.h:1860
clang::DeclarationName::isIdentifier
bool isIdentifier() const
Predicate functions for querying what type of name this is.
Definition: DeclarationName.h:375
llvm::ArrayRef
Definition: LLVM.h:34
State
LineState State
Definition: UnwrappedLineFormatter.cpp:987
clang::NamedDecl::getQualifiedNameAsString
std::string getQualifiedNameAsString() const
Definition: Decl.cpp:1582
clang::IdentifierInfo
One of these records is kept for each identifier that is lexed.
Definition: IdentifierTable.h:84
CheckerContext.h
clang::Type::isBooleanType
bool isBooleanType() const
Definition: Type.h:7075
clang::ObjCPropertyAttribute::Kind
Kind
Definition: DeclObjCCommon.h:22
Checker.h
clang::IdentifierInfo::getName
StringRef getName() const
Return the actual identifier string.
Definition: IdentifierTable.h:195
clang::Builtin::ID
ID
Definition: Builtins.h:48
clang
Definition: CalledOnceCheck.h:17
clang::Stmt
Stmt - This represents one statement.
Definition: Stmt.h:69
clang::ento::PathDiagnosticLocation::createBegin
static PathDiagnosticLocation createBegin(const Decl *D, const SourceManager &SM)
Create a location for the beginning of the declaration.
Definition: PathDiagnostic.cpp:580
clang::NamedDecl::getDeclName
DeclarationName getDeclName() const
Get the actual, stored name of the declaration, which may be a special name.
Definition: Decl.h:313
clang::ento::InvalidatedSymbols
llvm::DenseSet< SymbolRef > InvalidatedSymbols
Definition: Store.h:51
clang::LocationContext::getDecl
const Decl * getDecl() const
Definition: AnalysisDeclContext.h:247
clang::ento::move::isMovedFrom
bool isMovedFrom(ProgramStateRef State, const MemRegion *Region)
Returns true if the object is known to have been recently std::moved.
Definition: MoveChecker.cpp:235
clang::operator==
bool operator==(const CallGraphNode::CallRecord &LHS, const CallGraphNode::CallRecord &RHS)
Definition: CallGraph.h:207
llvm::IntrusiveRefCntPtr< const ProgramState >
clang::ento::ObjKind::OS
@ OS
Indicates that the tracking object is a descendant of a referenced-counted OSObject,...
clang::ReturnStmt
ReturnStmt - This represents a return, optionally of an expression: return; return 4;.
Definition: Stmt.h:2765
clang::CXXMethodDecl
Represents a static or instance method of a struct/union/class.
Definition: DeclCXX.h:1948
clang::Decl::getDeclContext
DeclContext * getDeclContext()
Definition: DeclBase.h:439
clang::NamedDecl::getName
StringRef getName() const
Get the name of identifier for this declaration as a StringRef.
Definition: Decl.h:276