clang  10.0.0svn
BugReporterVisitors.cpp
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1 //===- BugReporterVisitors.cpp - Helpers for reporting bugs ---------------===//
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 file defines a set of BugReporter "visitors" which can be used to
10 // enhance the diagnostics reported for a bug.
11 //
12 //===----------------------------------------------------------------------===//
13 
15 #include "clang/AST/ASTContext.h"
16 #include "clang/AST/Decl.h"
17 #include "clang/AST/DeclBase.h"
18 #include "clang/AST/DeclCXX.h"
19 #include "clang/AST/Expr.h"
20 #include "clang/AST/ExprCXX.h"
21 #include "clang/AST/ExprObjC.h"
22 #include "clang/AST/Stmt.h"
23 #include "clang/AST/Type.h"
27 #include "clang/Analysis/CFG.h"
32 #include "clang/Basic/LLVM.h"
35 #include "clang/Lex/Lexer.h"
49 #include "llvm/ADT/ArrayRef.h"
50 #include "llvm/ADT/None.h"
51 #include "llvm/ADT/Optional.h"
52 #include "llvm/ADT/STLExtras.h"
53 #include "llvm/ADT/SmallPtrSet.h"
54 #include "llvm/ADT/SmallString.h"
55 #include "llvm/ADT/SmallVector.h"
56 #include "llvm/ADT/StringExtras.h"
57 #include "llvm/ADT/StringRef.h"
58 #include "llvm/Support/Casting.h"
59 #include "llvm/Support/ErrorHandling.h"
60 #include "llvm/Support/raw_ostream.h"
61 #include <cassert>
62 #include <deque>
63 #include <memory>
64 #include <string>
65 #include <utility>
66 
67 using namespace clang;
68 using namespace ento;
69 
70 //===----------------------------------------------------------------------===//
71 // Utility functions.
72 //===----------------------------------------------------------------------===//
73 
74 static const Expr *peelOffPointerArithmetic(const BinaryOperator *B) {
75  if (B->isAdditiveOp() && B->getType()->isPointerType()) {
76  if (B->getLHS()->getType()->isPointerType()) {
77  return B->getLHS();
78  } else if (B->getRHS()->getType()->isPointerType()) {
79  return B->getRHS();
80  }
81  }
82  return nullptr;
83 }
84 
85 /// Given that expression S represents a pointer that would be dereferenced,
86 /// try to find a sub-expression from which the pointer came from.
87 /// This is used for tracking down origins of a null or undefined value:
88 /// "this is null because that is null because that is null" etc.
89 /// We wipe away field and element offsets because they merely add offsets.
90 /// We also wipe away all casts except lvalue-to-rvalue casts, because the
91 /// latter represent an actual pointer dereference; however, we remove
92 /// the final lvalue-to-rvalue cast before returning from this function
93 /// because it demonstrates more clearly from where the pointer rvalue was
94 /// loaded. Examples:
95 /// x->y.z ==> x (lvalue)
96 /// foo()->y.z ==> foo() (rvalue)
97 const Expr *bugreporter::getDerefExpr(const Stmt *S) {
98  const auto *E = dyn_cast<Expr>(S);
99  if (!E)
100  return nullptr;
101 
102  while (true) {
103  if (const auto *CE = dyn_cast<CastExpr>(E)) {
104  if (CE->getCastKind() == CK_LValueToRValue) {
105  // This cast represents the load we're looking for.
106  break;
107  }
108  E = CE->getSubExpr();
109  } else if (const auto *B = dyn_cast<BinaryOperator>(E)) {
110  // Pointer arithmetic: '*(x + 2)' -> 'x') etc.
111  if (const Expr *Inner = peelOffPointerArithmetic(B)) {
112  E = Inner;
113  } else {
114  // Probably more arithmetic can be pattern-matched here,
115  // but for now give up.
116  break;
117  }
118  } else if (const auto *U = dyn_cast<UnaryOperator>(E)) {
119  if (U->getOpcode() == UO_Deref || U->getOpcode() == UO_AddrOf ||
120  (U->isIncrementDecrementOp() && U->getType()->isPointerType())) {
121  // Operators '*' and '&' don't actually mean anything.
122  // We look at casts instead.
123  E = U->getSubExpr();
124  } else {
125  // Probably more arithmetic can be pattern-matched here,
126  // but for now give up.
127  break;
128  }
129  }
130  // Pattern match for a few useful cases: a[0], p->f, *p etc.
131  else if (const auto *ME = dyn_cast<MemberExpr>(E)) {
132  E = ME->getBase();
133  } else if (const auto *IvarRef = dyn_cast<ObjCIvarRefExpr>(E)) {
134  E = IvarRef->getBase();
135  } else if (const auto *AE = dyn_cast<ArraySubscriptExpr>(E)) {
136  E = AE->getBase();
137  } else if (const auto *PE = dyn_cast<ParenExpr>(E)) {
138  E = PE->getSubExpr();
139  } else if (const auto *FE = dyn_cast<FullExpr>(E)) {
140  E = FE->getSubExpr();
141  } else {
142  // Other arbitrary stuff.
143  break;
144  }
145  }
146 
147  // Special case: remove the final lvalue-to-rvalue cast, but do not recurse
148  // deeper into the sub-expression. This way we return the lvalue from which
149  // our pointer rvalue was loaded.
150  if (const auto *CE = dyn_cast<ImplicitCastExpr>(E))
151  if (CE->getCastKind() == CK_LValueToRValue)
152  E = CE->getSubExpr();
153 
154  return E;
155 }
156 
157 /// Comparing internal representations of symbolic values (via
158 /// SVal::operator==()) is a valid way to check if the value was updated,
159 /// unless it's a LazyCompoundVal that may have a different internal
160 /// representation every time it is loaded from the state. In this function we
161 /// do an approximate comparison for lazy compound values, checking that they
162 /// are the immediate snapshots of the tracked region's bindings within the
163 /// node's respective states but not really checking that these snapshots
164 /// actually contain the same set of bindings.
165 static bool hasVisibleUpdate(const ExplodedNode *LeftNode, SVal LeftVal,
166  const ExplodedNode *RightNode, SVal RightVal) {
167  if (LeftVal == RightVal)
168  return true;
169 
170  const auto LLCV = LeftVal.getAs<nonloc::LazyCompoundVal>();
171  if (!LLCV)
172  return false;
173 
174  const auto RLCV = RightVal.getAs<nonloc::LazyCompoundVal>();
175  if (!RLCV)
176  return false;
177 
178  return LLCV->getRegion() == RLCV->getRegion() &&
179  LLCV->getStore() == LeftNode->getState()->getStore() &&
180  RLCV->getStore() == RightNode->getState()->getStore();
181 }
182 
183 static Optional<SVal> getSValForVar(const Expr *CondVarExpr,
184  const ExplodedNode *N) {
185  ProgramStateRef State = N->getState();
186  const LocationContext *LCtx = N->getLocationContext();
187 
188  assert(CondVarExpr);
189  CondVarExpr = CondVarExpr->IgnoreImpCasts();
190 
191  // The declaration of the value may rely on a pointer so take its l-value.
192  // FIXME: As seen in VisitCommonDeclRefExpr, sometimes DeclRefExpr may
193  // evaluate to a FieldRegion when it refers to a declaration of a lambda
194  // capture variable. We most likely need to duplicate that logic here.
195  if (const auto *DRE = dyn_cast<DeclRefExpr>(CondVarExpr))
196  if (const auto *VD = dyn_cast<VarDecl>(DRE->getDecl()))
197  return State->getSVal(State->getLValue(VD, LCtx));
198 
199  if (const auto *ME = dyn_cast<MemberExpr>(CondVarExpr))
200  if (const auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl()))
201  if (auto FieldL = State->getSVal(ME, LCtx).getAs<Loc>())
202  return State->getRawSVal(*FieldL, FD->getType());
203 
204  return None;
205 }
206 
208 getConcreteIntegerValue(const Expr *CondVarExpr, const ExplodedNode *N) {
209 
210  if (Optional<SVal> V = getSValForVar(CondVarExpr, N))
211  if (auto CI = V->getAs<nonloc::ConcreteInt>())
212  return &CI->getValue();
213  return None;
214 }
215 
216 static bool isVarAnInterestingCondition(const Expr *CondVarExpr,
217  const ExplodedNode *N,
218  const PathSensitiveBugReport *B) {
219  // Even if this condition is marked as interesting, it isn't *that*
220  // interesting if it didn't happen in a nested stackframe, the user could just
221  // follow the arrows.
222  if (!B->getErrorNode()->getStackFrame()->isParentOf(N->getStackFrame()))
223  return false;
224 
225  if (Optional<SVal> V = getSValForVar(CondVarExpr, N))
226  if (Optional<bugreporter::TrackingKind> K = B->getInterestingnessKind(*V))
227  return *K == bugreporter::TrackingKind::Condition;
228 
229  return false;
230 }
231 
232 static bool isInterestingExpr(const Expr *E, const ExplodedNode *N,
233  const PathSensitiveBugReport *B) {
234  if (Optional<SVal> V = getSValForVar(E, N))
235  return B->getInterestingnessKind(*V).hasValue();
236  return false;
237 }
238 
239 /// \return name of the macro inside the location \p Loc.
240 static StringRef getMacroName(SourceLocation Loc,
241  BugReporterContext &BRC) {
243  Loc,
244  BRC.getSourceManager(),
245  BRC.getASTContext().getLangOpts());
246 }
247 
248 /// \return Whether given spelling location corresponds to an expansion
249 /// of a function-like macro.
251  const SourceManager &SM) {
252  if (!Loc.isMacroID())
253  return false;
254  while (SM.isMacroArgExpansion(Loc))
255  Loc = SM.getImmediateExpansionRange(Loc).getBegin();
256  std::pair<FileID, unsigned> TLInfo = SM.getDecomposedLoc(Loc);
257  SrcMgr::SLocEntry SE = SM.getSLocEntry(TLInfo.first);
258  const SrcMgr::ExpansionInfo &EInfo = SE.getExpansion();
259  return EInfo.isFunctionMacroExpansion();
260 }
261 
262 /// \return Whether \c RegionOfInterest was modified at \p N,
263 /// where \p ValueAfter is \c RegionOfInterest's value at the end of the
264 /// stack frame.
265 static bool wasRegionOfInterestModifiedAt(const SubRegion *RegionOfInterest,
266  const ExplodedNode *N,
267  SVal ValueAfter) {
268  ProgramStateRef State = N->getState();
269  ProgramStateManager &Mgr = N->getState()->getStateManager();
270 
271  if (!N->getLocationAs<PostStore>() && !N->getLocationAs<PostInitializer>() &&
272  !N->getLocationAs<PostStmt>())
273  return false;
274 
275  // Writing into region of interest.
276  if (auto PS = N->getLocationAs<PostStmt>())
277  if (auto *BO = PS->getStmtAs<BinaryOperator>())
278  if (BO->isAssignmentOp() && RegionOfInterest->isSubRegionOf(
279  N->getSVal(BO->getLHS()).getAsRegion()))
280  return true;
281 
282  // SVal after the state is possibly different.
283  SVal ValueAtN = N->getState()->getSVal(RegionOfInterest);
284  if (!Mgr.getSValBuilder()
285  .areEqual(State, ValueAtN, ValueAfter)
286  .isConstrainedTrue() &&
287  (!ValueAtN.isUndef() || !ValueAfter.isUndef()))
288  return true;
289 
290  return false;
291 }
292 
293 //===----------------------------------------------------------------------===//
294 // Implementation of BugReporterVisitor.
295 //===----------------------------------------------------------------------===//
296 
297 PathDiagnosticPieceRef BugReporterVisitor::getEndPath(BugReporterContext &,
298  const ExplodedNode *,
299  PathSensitiveBugReport &) {
300  return nullptr;
301 }
302 
303 void BugReporterVisitor::finalizeVisitor(BugReporterContext &,
304  const ExplodedNode *,
305  PathSensitiveBugReport &) {}
306 
308 BugReporterVisitor::getDefaultEndPath(const BugReporterContext &BRC,
309  const ExplodedNode *EndPathNode,
310  const PathSensitiveBugReport &BR) {
311  PathDiagnosticLocation L = BR.getLocation();
312  const auto &Ranges = BR.getRanges();
313 
314  // Only add the statement itself as a range if we didn't specify any
315  // special ranges for this report.
316  auto P = std::make_shared<PathDiagnosticEventPiece>(
317  L, BR.getDescription(), Ranges.begin() == Ranges.end());
318  for (SourceRange Range : Ranges)
319  P->addRange(Range);
320 
321  return P;
322 }
323 
324 //===----------------------------------------------------------------------===//
325 // Implementation of NoStoreFuncVisitor.
326 //===----------------------------------------------------------------------===//
327 
328 namespace {
329 
330 /// Put a diagnostic on return statement of all inlined functions
331 /// for which the region of interest \p RegionOfInterest was passed into,
332 /// but not written inside, and it has caused an undefined read or a null
333 /// pointer dereference outside.
334 class NoStoreFuncVisitor final : public BugReporterVisitor {
335  const SubRegion *RegionOfInterest;
336  MemRegionManager &MmrMgr;
337  const SourceManager &SM;
338  const PrintingPolicy &PP;
339  bugreporter::TrackingKind TKind;
340 
341  /// Recursion limit for dereferencing fields when looking for the
342  /// region of interest.
343  /// The limit of two indicates that we will dereference fields only once.
344  static const unsigned DEREFERENCE_LIMIT = 2;
345 
346  /// Frames writing into \c RegionOfInterest.
347  /// This visitor generates a note only if a function does not write into
348  /// a region of interest. This information is not immediately available
349  /// by looking at the node associated with the exit from the function
350  /// (usually the return statement). To avoid recomputing the same information
351  /// many times (going up the path for each node and checking whether the
352  /// region was written into) we instead lazily compute the
353  /// stack frames along the path which write into the region of interest.
354  llvm::SmallPtrSet<const StackFrameContext *, 32> FramesModifyingRegion;
355  llvm::SmallPtrSet<const StackFrameContext *, 32> FramesModifyingCalculated;
356 
357  using RegionVector = SmallVector<const MemRegion *, 5>;
358 
359 public:
360  NoStoreFuncVisitor(const SubRegion *R, bugreporter::TrackingKind TKind)
361  : RegionOfInterest(R), MmrMgr(*R->getMemRegionManager()),
362  SM(MmrMgr.getContext().getSourceManager()),
363  PP(MmrMgr.getContext().getPrintingPolicy()), TKind(TKind) {}
364 
365  void Profile(llvm::FoldingSetNodeID &ID) const override {
366  static int Tag = 0;
367  ID.AddPointer(&Tag);
368  ID.AddPointer(RegionOfInterest);
369  }
370 
371  void *getTag() const {
372  static int Tag = 0;
373  return static_cast<void *>(&Tag);
374  }
375 
376  PathDiagnosticPieceRef VisitNode(const ExplodedNode *N,
377  BugReporterContext &BR,
378  PathSensitiveBugReport &R) override;
379 
380 private:
381  /// Attempts to find the region of interest in a given record decl,
382  /// by either following the base classes or fields.
383  /// Dereferences fields up to a given recursion limit.
384  /// Note that \p Vec is passed by value, leading to quadratic copying cost,
385  /// but it's OK in practice since its length is limited to DEREFERENCE_LIMIT.
386  /// \return A chain fields leading to the region of interest or None.
388  findRegionOfInterestInRecord(const RecordDecl *RD, ProgramStateRef State,
389  const MemRegion *R, const RegionVector &Vec = {},
390  int depth = 0);
391 
392  /// Check and lazily calculate whether the region of interest is
393  /// modified in the stack frame to which \p N belongs.
394  /// The calculation is cached in FramesModifyingRegion.
395  bool isRegionOfInterestModifiedInFrame(const ExplodedNode *N) {
396  const LocationContext *Ctx = N->getLocationContext();
397  const StackFrameContext *SCtx = Ctx->getStackFrame();
398  if (!FramesModifyingCalculated.count(SCtx))
399  findModifyingFrames(N);
400  return FramesModifyingRegion.count(SCtx);
401  }
402 
403  /// Write to \c FramesModifyingRegion all stack frames along
404  /// the path in the current stack frame which modify \c RegionOfInterest.
405  void findModifyingFrames(const ExplodedNode *N);
406 
407  /// Consume the information on the no-store stack frame in order to
408  /// either emit a note or suppress the report enirely.
409  /// \return Diagnostics piece for region not modified in the current function,
410  /// if it decides to emit one.
412  maybeEmitNote(PathSensitiveBugReport &R, const CallEvent &Call,
413  const ExplodedNode *N, const RegionVector &FieldChain,
414  const MemRegion *MatchedRegion, StringRef FirstElement,
415  bool FirstIsReferenceType, unsigned IndirectionLevel);
416 
417  /// Pretty-print region \p MatchedRegion to \p os.
418  /// \return Whether printing succeeded.
419  bool prettyPrintRegionName(StringRef FirstElement, bool FirstIsReferenceType,
420  const MemRegion *MatchedRegion,
421  const RegionVector &FieldChain,
422  int IndirectionLevel,
423  llvm::raw_svector_ostream &os);
424 
425  /// Print first item in the chain, return new separator.
426  static StringRef prettyPrintFirstElement(StringRef FirstElement,
427  bool MoreItemsExpected,
428  int IndirectionLevel,
429  llvm::raw_svector_ostream &os);
430 };
431 
432 } // end of anonymous namespace
433 
434 /// \return Whether the method declaration \p Parent
435 /// syntactically has a binary operation writing into the ivar \p Ivar.
437  const ObjCIvarDecl *Ivar) {
438  using namespace ast_matchers;
439  const char *IvarBind = "Ivar";
440  if (!Parent || !Parent->hasBody())
441  return false;
442  StatementMatcher WriteIntoIvarM = binaryOperator(
443  hasOperatorName("="),
444  hasLHS(ignoringParenImpCasts(
445  objcIvarRefExpr(hasDeclaration(equalsNode(Ivar))).bind(IvarBind))));
446  StatementMatcher ParentM = stmt(hasDescendant(WriteIntoIvarM));
447  auto Matches = match(ParentM, *Parent->getBody(), Parent->getASTContext());
448  for (BoundNodes &Match : Matches) {
449  auto IvarRef = Match.getNodeAs<ObjCIvarRefExpr>(IvarBind);
450  if (IvarRef->isFreeIvar())
451  return true;
452 
453  const Expr *Base = IvarRef->getBase();
454  if (const auto *ICE = dyn_cast<ImplicitCastExpr>(Base))
455  Base = ICE->getSubExpr();
456 
457  if (const auto *DRE = dyn_cast<DeclRefExpr>(Base))
458  if (const auto *ID = dyn_cast<ImplicitParamDecl>(DRE->getDecl()))
459  if (ID->getParameterKind() == ImplicitParamDecl::ObjCSelf)
460  return true;
461 
462  return false;
463  }
464  return false;
465 }
466 
467 /// Get parameters associated with runtime definition in order
468 /// to get the correct parameter name.
469 static ArrayRef<ParmVarDecl *> getCallParameters(CallEventRef<> Call) {
470  // Use runtime definition, if available.
471  RuntimeDefinition RD = Call->getRuntimeDefinition();
472  if (const auto *FD = dyn_cast_or_null<FunctionDecl>(RD.getDecl()))
473  return FD->parameters();
474  if (const auto *MD = dyn_cast_or_null<ObjCMethodDecl>(RD.getDecl()))
475  return MD->parameters();
476 
477  return Call->parameters();
478 }
479 
480 /// \return whether \p Ty points to a const type, or is a const reference.
481 static bool isPointerToConst(QualType Ty) {
482  return !Ty->getPointeeType().isNull() &&
484 }
485 
486 /// Attempts to find the region of interest in a given CXX decl,
487 /// by either following the base classes or fields.
488 /// Dereferences fields up to a given recursion limit.
489 /// Note that \p Vec is passed by value, leading to quadratic copying cost,
490 /// but it's OK in practice since its length is limited to DEREFERENCE_LIMIT.
491 /// \return A chain fields leading to the region of interest or None.
493 NoStoreFuncVisitor::findRegionOfInterestInRecord(
494  const RecordDecl *RD, ProgramStateRef State, const MemRegion *R,
495  const NoStoreFuncVisitor::RegionVector &Vec /* = {} */,
496  int depth /* = 0 */) {
497 
498  if (depth == DEREFERENCE_LIMIT) // Limit the recursion depth.
499  return None;
500 
501  if (const auto *RDX = dyn_cast<CXXRecordDecl>(RD))
502  if (!RDX->hasDefinition())
503  return None;
504 
505  // Recursively examine the base classes.
506  // Note that following base classes does not increase the recursion depth.
507  if (const auto *RDX = dyn_cast<CXXRecordDecl>(RD))
508  for (const auto II : RDX->bases())
509  if (const RecordDecl *RRD = II.getType()->getAsRecordDecl())
510  if (Optional<RegionVector> Out =
511  findRegionOfInterestInRecord(RRD, State, R, Vec, depth))
512  return Out;
513 
514  for (const FieldDecl *I : RD->fields()) {
515  QualType FT = I->getType();
516  const FieldRegion *FR = MmrMgr.getFieldRegion(I, cast<SubRegion>(R));
517  const SVal V = State->getSVal(FR);
518  const MemRegion *VR = V.getAsRegion();
519 
520  RegionVector VecF = Vec;
521  VecF.push_back(FR);
522 
523  if (RegionOfInterest == VR)
524  return VecF;
525 
526  if (const RecordDecl *RRD = FT->getAsRecordDecl())
527  if (auto Out =
528  findRegionOfInterestInRecord(RRD, State, FR, VecF, depth + 1))
529  return Out;
530 
531  QualType PT = FT->getPointeeType();
532  if (PT.isNull() || PT->isVoidType() || !VR)
533  continue;
534 
535  if (const RecordDecl *RRD = PT->getAsRecordDecl())
536  if (Optional<RegionVector> Out =
537  findRegionOfInterestInRecord(RRD, State, VR, VecF, depth + 1))
538  return Out;
539  }
540 
541  return None;
542 }
543 
545 NoStoreFuncVisitor::VisitNode(const ExplodedNode *N, BugReporterContext &BR,
546  PathSensitiveBugReport &R) {
547 
548  const LocationContext *Ctx = N->getLocationContext();
549  const StackFrameContext *SCtx = Ctx->getStackFrame();
550  ProgramStateRef State = N->getState();
551  auto CallExitLoc = N->getLocationAs<CallExitBegin>();
552 
553  // No diagnostic if region was modified inside the frame.
554  if (!CallExitLoc || isRegionOfInterestModifiedInFrame(N))
555  return nullptr;
556 
557  CallEventRef<> Call =
558  BR.getStateManager().getCallEventManager().getCaller(SCtx, State);
559 
560  // Region of interest corresponds to an IVar, exiting a method
561  // which could have written into that IVar, but did not.
562  if (const auto *MC = dyn_cast<ObjCMethodCall>(Call)) {
563  if (const auto *IvarR = dyn_cast<ObjCIvarRegion>(RegionOfInterest)) {
564  const MemRegion *SelfRegion = MC->getReceiverSVal().getAsRegion();
565  if (RegionOfInterest->isSubRegionOf(SelfRegion) &&
566  potentiallyWritesIntoIvar(Call->getRuntimeDefinition().getDecl(),
567  IvarR->getDecl()))
568  return maybeEmitNote(R, *Call, N, {}, SelfRegion, "self",
569  /*FirstIsReferenceType=*/false, 1);
570  }
571  }
572 
573  if (const auto *CCall = dyn_cast<CXXConstructorCall>(Call)) {
574  const MemRegion *ThisR = CCall->getCXXThisVal().getAsRegion();
575  if (RegionOfInterest->isSubRegionOf(ThisR) &&
576  !CCall->getDecl()->isImplicit())
577  return maybeEmitNote(R, *Call, N, {}, ThisR, "this",
578  /*FirstIsReferenceType=*/false, 1);
579 
580  // Do not generate diagnostics for not modified parameters in
581  // constructors.
582  return nullptr;
583  }
584 
585  ArrayRef<ParmVarDecl *> parameters = getCallParameters(Call);
586  for (unsigned I = 0; I < Call->getNumArgs() && I < parameters.size(); ++I) {
587  const ParmVarDecl *PVD = parameters[I];
588  SVal V = Call->getArgSVal(I);
589  bool ParamIsReferenceType = PVD->getType()->isReferenceType();
590  std::string ParamName = PVD->getNameAsString();
591 
592  int IndirectionLevel = 1;
593  QualType T = PVD->getType();
594  while (const MemRegion *MR = V.getAsRegion()) {
595  if (RegionOfInterest->isSubRegionOf(MR) && !isPointerToConst(T))
596  return maybeEmitNote(R, *Call, N, {}, MR, ParamName,
597  ParamIsReferenceType, IndirectionLevel);
598 
599  QualType PT = T->getPointeeType();
600  if (PT.isNull() || PT->isVoidType())
601  break;
602 
603  if (const RecordDecl *RD = PT->getAsRecordDecl())
605  findRegionOfInterestInRecord(RD, State, MR))
606  return maybeEmitNote(R, *Call, N, *P, RegionOfInterest, ParamName,
607  ParamIsReferenceType, IndirectionLevel);
608 
609  V = State->getSVal(MR, PT);
610  T = PT;
611  IndirectionLevel++;
612  }
613  }
614 
615  return nullptr;
616 }
617 
618 void NoStoreFuncVisitor::findModifyingFrames(const ExplodedNode *N) {
619  assert(N->getLocationAs<CallExitBegin>());
620  ProgramStateRef LastReturnState = N->getState();
621  SVal ValueAtReturn = LastReturnState->getSVal(RegionOfInterest);
622  const LocationContext *Ctx = N->getLocationContext();
623  const StackFrameContext *OriginalSCtx = Ctx->getStackFrame();
624 
625  do {
626  ProgramStateRef State = N->getState();
627  auto CallExitLoc = N->getLocationAs<CallExitBegin>();
628  if (CallExitLoc) {
629  LastReturnState = State;
630  ValueAtReturn = LastReturnState->getSVal(RegionOfInterest);
631  }
632 
633  FramesModifyingCalculated.insert(N->getLocationContext()->getStackFrame());
634 
635  if (wasRegionOfInterestModifiedAt(RegionOfInterest, N, ValueAtReturn)) {
636  const StackFrameContext *SCtx = N->getStackFrame();
637  while (!SCtx->inTopFrame()) {
638  auto p = FramesModifyingRegion.insert(SCtx);
639  if (!p.second)
640  break; // Frame and all its parents already inserted.
641  SCtx = SCtx->getParent()->getStackFrame();
642  }
643  }
644 
645  // Stop calculation at the call to the current function.
646  if (auto CE = N->getLocationAs<CallEnter>())
647  if (CE->getCalleeContext() == OriginalSCtx)
648  break;
649 
650  N = N->getFirstPred();
651  } while (N);
652 }
653 
654 static llvm::StringLiteral WillBeUsedForACondition =
655  ", which participates in a condition later";
656 
657 PathDiagnosticPieceRef NoStoreFuncVisitor::maybeEmitNote(
658  PathSensitiveBugReport &R, const CallEvent &Call, const ExplodedNode *N,
659  const RegionVector &FieldChain, const MemRegion *MatchedRegion,
660  StringRef FirstElement, bool FirstIsReferenceType,
661  unsigned IndirectionLevel) {
662  // Optimistically suppress uninitialized value bugs that result
663  // from system headers having a chance to initialize the value
664  // but failing to do so. It's too unlikely a system header's fault.
665  // It's much more likely a situation in which the function has a failure
666  // mode that the user decided not to check. If we want to hunt such
667  // omitted checks, we should provide an explicit function-specific note
668  // describing the precondition under which the function isn't supposed to
669  // initialize its out-parameter, and additionally check that such
670  // precondition can actually be fulfilled on the current path.
671  if (Call.isInSystemHeader()) {
672  // We make an exception for system header functions that have no branches.
673  // Such functions unconditionally fail to initialize the variable.
674  // If they call other functions that have more paths within them,
675  // this suppression would still apply when we visit these inner functions.
676  // One common example of a standard function that doesn't ever initialize
677  // its out parameter is operator placement new; it's up to the follow-up
678  // constructor (if any) to initialize the memory.
679  if (!N->getStackFrame()->getCFG()->isLinear())
680  R.markInvalid(getTag(), nullptr);
681  return nullptr;
682  }
683 
684  PathDiagnosticLocation L =
685  PathDiagnosticLocation::create(N->getLocation(), SM);
686 
687  // For now this shouldn't trigger, but once it does (as we add more
688  // functions to the body farm), we'll need to decide if these reports
689  // are worth suppressing as well.
690  if (!L.hasValidLocation())
691  return nullptr;
692 
693  SmallString<256> sbuf;
694  llvm::raw_svector_ostream os(sbuf);
695  os << "Returning without writing to '";
696 
697  // Do not generate the note if failed to pretty-print.
698  if (!prettyPrintRegionName(FirstElement, FirstIsReferenceType, MatchedRegion,
699  FieldChain, IndirectionLevel, os))
700  return nullptr;
701 
702  os << "'";
703  if (TKind == bugreporter::TrackingKind::Condition)
705  return std::make_shared<PathDiagnosticEventPiece>(L, os.str());
706 }
707 
708 bool NoStoreFuncVisitor::prettyPrintRegionName(StringRef FirstElement,
709  bool FirstIsReferenceType,
710  const MemRegion *MatchedRegion,
711  const RegionVector &FieldChain,
712  int IndirectionLevel,
713  llvm::raw_svector_ostream &os) {
714 
715  if (FirstIsReferenceType)
716  IndirectionLevel--;
717 
718  RegionVector RegionSequence;
719 
720  // Add the regions in the reverse order, then reverse the resulting array.
721  assert(RegionOfInterest->isSubRegionOf(MatchedRegion));
722  const MemRegion *R = RegionOfInterest;
723  while (R != MatchedRegion) {
724  RegionSequence.push_back(R);
725  R = cast<SubRegion>(R)->getSuperRegion();
726  }
727  std::reverse(RegionSequence.begin(), RegionSequence.end());
728  RegionSequence.append(FieldChain.begin(), FieldChain.end());
729 
730  StringRef Sep;
731  for (const MemRegion *R : RegionSequence) {
732 
733  // Just keep going up to the base region.
734  // Element regions may appear due to casts.
735  if (isa<CXXBaseObjectRegion>(R) || isa<CXXTempObjectRegion>(R))
736  continue;
737 
738  if (Sep.empty())
739  Sep = prettyPrintFirstElement(FirstElement,
740  /*MoreItemsExpected=*/true,
741  IndirectionLevel, os);
742 
743  os << Sep;
744 
745  // Can only reasonably pretty-print DeclRegions.
746  if (!isa<DeclRegion>(R))
747  return false;
748 
749  const auto *DR = cast<DeclRegion>(R);
750  Sep = DR->getValueType()->isAnyPointerType() ? "->" : ".";
751  DR->getDecl()->getDeclName().print(os, PP);
752  }
753 
754  if (Sep.empty())
755  prettyPrintFirstElement(FirstElement,
756  /*MoreItemsExpected=*/false, IndirectionLevel, os);
757  return true;
758 }
759 
760 StringRef NoStoreFuncVisitor::prettyPrintFirstElement(
761  StringRef FirstElement, bool MoreItemsExpected, int IndirectionLevel,
762  llvm::raw_svector_ostream &os) {
763  StringRef Out = ".";
764 
765  if (IndirectionLevel > 0 && MoreItemsExpected) {
766  IndirectionLevel--;
767  Out = "->";
768  }
769 
770  if (IndirectionLevel > 0 && MoreItemsExpected)
771  os << "(";
772 
773  for (int i = 0; i < IndirectionLevel; i++)
774  os << "*";
775  os << FirstElement;
776 
777  if (IndirectionLevel > 0 && MoreItemsExpected)
778  os << ")";
779 
780  return Out;
781 }
782 
783 //===----------------------------------------------------------------------===//
784 // Implementation of MacroNullReturnSuppressionVisitor.
785 //===----------------------------------------------------------------------===//
786 
787 namespace {
788 
789 /// Suppress null-pointer-dereference bugs where dereferenced null was returned
790 /// the macro.
791 class MacroNullReturnSuppressionVisitor final : public BugReporterVisitor {
792  const SubRegion *RegionOfInterest;
793  const SVal ValueAtDereference;
794 
795  // Do not invalidate the reports where the value was modified
796  // after it got assigned to from the macro.
797  bool WasModified = false;
798 
799 public:
800  MacroNullReturnSuppressionVisitor(const SubRegion *R, const SVal V)
801  : RegionOfInterest(R), ValueAtDereference(V) {}
802 
803  PathDiagnosticPieceRef VisitNode(const ExplodedNode *N,
804  BugReporterContext &BRC,
805  PathSensitiveBugReport &BR) override {
806  if (WasModified)
807  return nullptr;
808 
809  auto BugPoint = BR.getErrorNode()->getLocation().getAs<StmtPoint>();
810  if (!BugPoint)
811  return nullptr;
812 
813  const SourceManager &SMgr = BRC.getSourceManager();
814  if (auto Loc = matchAssignment(N)) {
815  if (isFunctionMacroExpansion(*Loc, SMgr)) {
816  std::string MacroName = getMacroName(*Loc, BRC);
817  SourceLocation BugLoc = BugPoint->getStmt()->getBeginLoc();
818  if (!BugLoc.isMacroID() || getMacroName(BugLoc, BRC) != MacroName)
819  BR.markInvalid(getTag(), MacroName.c_str());
820  }
821  }
822 
823  if (wasRegionOfInterestModifiedAt(RegionOfInterest, N, ValueAtDereference))
824  WasModified = true;
825 
826  return nullptr;
827  }
828 
829  static void addMacroVisitorIfNecessary(
830  const ExplodedNode *N, const MemRegion *R,
831  bool EnableNullFPSuppression, PathSensitiveBugReport &BR,
832  const SVal V) {
833  AnalyzerOptions &Options = N->getState()->getAnalysisManager().options;
834  if (EnableNullFPSuppression &&
835  Options.ShouldSuppressNullReturnPaths && V.getAs<Loc>())
836  BR.addVisitor(std::make_unique<MacroNullReturnSuppressionVisitor>(
837  R->getAs<SubRegion>(), V));
838  }
839 
840  void* getTag() const {
841  static int Tag = 0;
842  return static_cast<void *>(&Tag);
843  }
844 
845  void Profile(llvm::FoldingSetNodeID &ID) const override {
846  ID.AddPointer(getTag());
847  }
848 
849 private:
850  /// \return Source location of right hand side of an assignment
851  /// into \c RegionOfInterest, empty optional if none found.
852  Optional<SourceLocation> matchAssignment(const ExplodedNode *N) {
853  const Stmt *S = N->getStmtForDiagnostics();
854  ProgramStateRef State = N->getState();
855  auto *LCtx = N->getLocationContext();
856  if (!S)
857  return None;
858 
859  if (const auto *DS = dyn_cast<DeclStmt>(S)) {
860  if (const auto *VD = dyn_cast<VarDecl>(DS->getSingleDecl()))
861  if (const Expr *RHS = VD->getInit())
862  if (RegionOfInterest->isSubRegionOf(
863  State->getLValue(VD, LCtx).getAsRegion()))
864  return RHS->getBeginLoc();
865  } else if (const auto *BO = dyn_cast<BinaryOperator>(S)) {
866  const MemRegion *R = N->getSVal(BO->getLHS()).getAsRegion();
867  const Expr *RHS = BO->getRHS();
868  if (BO->isAssignmentOp() && RegionOfInterest->isSubRegionOf(R)) {
869  return RHS->getBeginLoc();
870  }
871  }
872  return None;
873  }
874 };
875 
876 } // end of anonymous namespace
877 
878 namespace {
879 
880 /// Emits an extra note at the return statement of an interesting stack frame.
881 ///
882 /// The returned value is marked as an interesting value, and if it's null,
883 /// adds a visitor to track where it became null.
884 ///
885 /// This visitor is intended to be used when another visitor discovers that an
886 /// interesting value comes from an inlined function call.
887 class ReturnVisitor : public BugReporterVisitor {
888  const StackFrameContext *CalleeSFC;
889  enum {
890  Initial,
891  MaybeUnsuppress,
892  Satisfied
893  } Mode = Initial;
894 
895  bool EnableNullFPSuppression;
896  bool ShouldInvalidate = true;
897  AnalyzerOptions& Options;
898  bugreporter::TrackingKind TKind;
899 
900 public:
901  ReturnVisitor(const StackFrameContext *Frame, bool Suppressed,
902  AnalyzerOptions &Options, bugreporter::TrackingKind TKind)
903  : CalleeSFC(Frame), EnableNullFPSuppression(Suppressed),
904  Options(Options), TKind(TKind) {}
905 
906  static void *getTag() {
907  static int Tag = 0;
908  return static_cast<void *>(&Tag);
909  }
910 
911  void Profile(llvm::FoldingSetNodeID &ID) const override {
912  ID.AddPointer(ReturnVisitor::getTag());
913  ID.AddPointer(CalleeSFC);
914  ID.AddBoolean(EnableNullFPSuppression);
915  }
916 
917  /// Adds a ReturnVisitor if the given statement represents a call that was
918  /// inlined.
919  ///
920  /// This will search back through the ExplodedGraph, starting from the given
921  /// node, looking for when the given statement was processed. If it turns out
922  /// the statement is a call that was inlined, we add the visitor to the
923  /// bug report, so it can print a note later.
924  static void addVisitorIfNecessary(const ExplodedNode *Node, const Stmt *S,
925  PathSensitiveBugReport &BR,
926  bool InEnableNullFPSuppression,
927  bugreporter::TrackingKind TKind) {
928  if (!CallEvent::isCallStmt(S))
929  return;
930 
931  // First, find when we processed the statement.
932  // If we work with a 'CXXNewExpr' that is going to be purged away before
933  // its call take place. We would catch that purge in the last condition
934  // as a 'StmtPoint' so we have to bypass it.
935  const bool BypassCXXNewExprEval = isa<CXXNewExpr>(S);
936 
937  // This is moving forward when we enter into another context.
938  const StackFrameContext *CurrentSFC = Node->getStackFrame();
939 
940  do {
941  // If that is satisfied we found our statement as an inlined call.
942  if (Optional<CallExitEnd> CEE = Node->getLocationAs<CallExitEnd>())
943  if (CEE->getCalleeContext()->getCallSite() == S)
944  break;
945 
946  // Try to move forward to the end of the call-chain.
947  Node = Node->getFirstPred();
948  if (!Node)
949  break;
950 
951  const StackFrameContext *PredSFC = Node->getStackFrame();
952 
953  // If that is satisfied we found our statement.
954  // FIXME: This code currently bypasses the call site for the
955  // conservatively evaluated allocator.
956  if (!BypassCXXNewExprEval)
957  if (Optional<StmtPoint> SP = Node->getLocationAs<StmtPoint>())
958  // See if we do not enter into another context.
959  if (SP->getStmt() == S && CurrentSFC == PredSFC)
960  break;
961 
962  CurrentSFC = PredSFC;
963  } while (Node->getStackFrame() == CurrentSFC);
964 
965  // Next, step over any post-statement checks.
966  while (Node && Node->getLocation().getAs<PostStmt>())
967  Node = Node->getFirstPred();
968  if (!Node)
969  return;
970 
971  // Finally, see if we inlined the call.
972  Optional<CallExitEnd> CEE = Node->getLocationAs<CallExitEnd>();
973  if (!CEE)
974  return;
975 
976  const StackFrameContext *CalleeContext = CEE->getCalleeContext();
977  if (CalleeContext->getCallSite() != S)
978  return;
979 
980  // Check the return value.
981  ProgramStateRef State = Node->getState();
982  SVal RetVal = Node->getSVal(S);
983 
984  // Handle cases where a reference is returned and then immediately used.
985  if (cast<Expr>(S)->isGLValue())
986  if (Optional<Loc> LValue = RetVal.getAs<Loc>())
987  RetVal = State->getSVal(*LValue);
988 
989  // See if the return value is NULL. If so, suppress the report.
990  AnalyzerOptions &Options = State->getAnalysisManager().options;
991 
992  bool EnableNullFPSuppression = false;
993  if (InEnableNullFPSuppression &&
994  Options.ShouldSuppressNullReturnPaths)
995  if (Optional<Loc> RetLoc = RetVal.getAs<Loc>())
996  EnableNullFPSuppression = State->isNull(*RetLoc).isConstrainedTrue();
997 
998  BR.addVisitor(std::make_unique<ReturnVisitor>(CalleeContext,
999  EnableNullFPSuppression,
1000  Options, TKind));
1001  }
1002 
1003  PathDiagnosticPieceRef visitNodeInitial(const ExplodedNode *N,
1004  BugReporterContext &BRC,
1005  PathSensitiveBugReport &BR) {
1006  // Only print a message at the interesting return statement.
1007  if (N->getLocationContext() != CalleeSFC)
1008  return nullptr;
1009 
1010  Optional<StmtPoint> SP = N->getLocationAs<StmtPoint>();
1011  if (!SP)
1012  return nullptr;
1013 
1014  const auto *Ret = dyn_cast<ReturnStmt>(SP->getStmt());
1015  if (!Ret)
1016  return nullptr;
1017 
1018  // Okay, we're at the right return statement, but do we have the return
1019  // value available?
1020  ProgramStateRef State = N->getState();
1021  SVal V = State->getSVal(Ret, CalleeSFC);
1022  if (V.isUnknownOrUndef())
1023  return nullptr;
1024 
1025  // Don't print any more notes after this one.
1026  Mode = Satisfied;
1027 
1028  const Expr *RetE = Ret->getRetValue();
1029  assert(RetE && "Tracking a return value for a void function");
1030 
1031  // Handle cases where a reference is returned and then immediately used.
1032  Optional<Loc> LValue;
1033  if (RetE->isGLValue()) {
1034  if ((LValue = V.getAs<Loc>())) {
1035  SVal RValue = State->getRawSVal(*LValue, RetE->getType());
1036  if (RValue.getAs<DefinedSVal>())
1037  V = RValue;
1038  }
1039  }
1040 
1041  // Ignore aggregate rvalues.
1042  if (V.getAs<nonloc::LazyCompoundVal>() ||
1043  V.getAs<nonloc::CompoundVal>())
1044  return nullptr;
1045 
1046  RetE = RetE->IgnoreParenCasts();
1047 
1048  // Let's track the return value.
1049  bugreporter::trackExpressionValue(
1050  N, RetE, BR, TKind, EnableNullFPSuppression);
1051 
1052  // Build an appropriate message based on the return value.
1053  SmallString<64> Msg;
1054  llvm::raw_svector_ostream Out(Msg);
1055 
1056  bool WouldEventBeMeaningless = false;
1057 
1058  if (State->isNull(V).isConstrainedTrue()) {
1059  if (V.getAs<Loc>()) {
1060 
1061  // If we have counter-suppression enabled, make sure we keep visiting
1062  // future nodes. We want to emit a path note as well, in case
1063  // the report is resurrected as valid later on.
1064  if (EnableNullFPSuppression &&
1065  Options.ShouldAvoidSuppressingNullArgumentPaths)
1066  Mode = MaybeUnsuppress;
1067 
1068  if (RetE->getType()->isObjCObjectPointerType()) {
1069  Out << "Returning nil";
1070  } else {
1071  Out << "Returning null pointer";
1072  }
1073  } else {
1074  Out << "Returning zero";
1075  }
1076 
1077  } else {
1078  if (auto CI = V.getAs<nonloc::ConcreteInt>()) {
1079  Out << "Returning the value " << CI->getValue();
1080  } else {
1081  // There is nothing interesting about returning a value, when it is
1082  // plain value without any constraints, and the function is guaranteed
1083  // to return that every time. We could use CFG::isLinear() here, but
1084  // constexpr branches are obvious to the compiler, not necesserily to
1085  // the programmer.
1086  if (N->getCFG().size() == 3)
1087  WouldEventBeMeaningless = true;
1088 
1089  if (V.getAs<Loc>())
1090  Out << "Returning pointer";
1091  else
1092  Out << "Returning value";
1093  }
1094  }
1095 
1096  if (LValue) {
1097  if (const MemRegion *MR = LValue->getAsRegion()) {
1098  if (MR->canPrintPretty()) {
1099  Out << " (reference to ";
1100  MR->printPretty(Out);
1101  Out << ")";
1102  }
1103  }
1104  } else {
1105  // FIXME: We should have a more generalized location printing mechanism.
1106  if (const auto *DR = dyn_cast<DeclRefExpr>(RetE))
1107  if (const auto *DD = dyn_cast<DeclaratorDecl>(DR->getDecl()))
1108  Out << " (loaded from '" << *DD << "')";
1109  }
1110 
1111  PathDiagnosticLocation L(Ret, BRC.getSourceManager(), CalleeSFC);
1112  if (!L.isValid() || !L.asLocation().isValid())
1113  return nullptr;
1114 
1115  if (TKind == bugreporter::TrackingKind::Condition)
1116  Out << WillBeUsedForACondition;
1117 
1118  auto EventPiece = std::make_shared<PathDiagnosticEventPiece>(L, Out.str());
1119 
1120  // If we determined that the note is meaningless, make it prunable, and
1121  // don't mark the stackframe interesting.
1122  if (WouldEventBeMeaningless)
1123  EventPiece->setPrunable(true);
1124  else
1125  BR.markInteresting(CalleeSFC);
1126 
1127  return EventPiece;
1128  }
1129 
1130  PathDiagnosticPieceRef visitNodeMaybeUnsuppress(const ExplodedNode *N,
1131  BugReporterContext &BRC,
1132  PathSensitiveBugReport &BR) {
1133  assert(Options.ShouldAvoidSuppressingNullArgumentPaths);
1134 
1135  // Are we at the entry node for this call?
1136  Optional<CallEnter> CE = N->getLocationAs<CallEnter>();
1137  if (!CE)
1138  return nullptr;
1139 
1140  if (CE->getCalleeContext() != CalleeSFC)
1141  return nullptr;
1142 
1143  Mode = Satisfied;
1144 
1145  // Don't automatically suppress a report if one of the arguments is
1146  // known to be a null pointer. Instead, start tracking /that/ null
1147  // value back to its origin.
1148  ProgramStateManager &StateMgr = BRC.getStateManager();
1149  CallEventManager &CallMgr = StateMgr.getCallEventManager();
1150 
1151  ProgramStateRef State = N->getState();
1152  CallEventRef<> Call = CallMgr.getCaller(CalleeSFC, State);
1153  for (unsigned I = 0, E = Call->getNumArgs(); I != E; ++I) {
1154  Optional<Loc> ArgV = Call->getArgSVal(I).getAs<Loc>();
1155  if (!ArgV)
1156  continue;
1157 
1158  const Expr *ArgE = Call->getArgExpr(I);
1159  if (!ArgE)
1160  continue;
1161 
1162  // Is it possible for this argument to be non-null?
1163  if (!State->isNull(*ArgV).isConstrainedTrue())
1164  continue;
1165 
1166  if (trackExpressionValue(N, ArgE, BR, TKind, EnableNullFPSuppression))
1167  ShouldInvalidate = false;
1168 
1169  // If we /can't/ track the null pointer, we should err on the side of
1170  // false negatives, and continue towards marking this report invalid.
1171  // (We will still look at the other arguments, though.)
1172  }
1173 
1174  return nullptr;
1175  }
1176 
1177  PathDiagnosticPieceRef VisitNode(const ExplodedNode *N,
1178  BugReporterContext &BRC,
1179  PathSensitiveBugReport &BR) override {
1180  switch (Mode) {
1181  case Initial:
1182  return visitNodeInitial(N, BRC, BR);
1183  case MaybeUnsuppress:
1184  return visitNodeMaybeUnsuppress(N, BRC, BR);
1185  case Satisfied:
1186  return nullptr;
1187  }
1188 
1189  llvm_unreachable("Invalid visit mode!");
1190  }
1191 
1192  void finalizeVisitor(BugReporterContext &, const ExplodedNode *,
1193  PathSensitiveBugReport &BR) override {
1194  if (EnableNullFPSuppression && ShouldInvalidate)
1195  BR.markInvalid(ReturnVisitor::getTag(), CalleeSFC);
1196  }
1197 };
1198 
1199 } // end of anonymous namespace
1200 
1201 //===----------------------------------------------------------------------===//
1202 // Implementation of FindLastStoreBRVisitor.
1203 //===----------------------------------------------------------------------===//
1204 
1205 void FindLastStoreBRVisitor::Profile(llvm::FoldingSetNodeID &ID) const {
1206  static int tag = 0;
1207  ID.AddPointer(&tag);
1208  ID.AddPointer(R);
1209  ID.Add(V);
1210  ID.AddInteger(static_cast<int>(TKind));
1211  ID.AddBoolean(EnableNullFPSuppression);
1212 }
1213 
1214 /// Returns true if \p N represents the DeclStmt declaring and initializing
1215 /// \p VR.
1216 static bool isInitializationOfVar(const ExplodedNode *N, const VarRegion *VR) {
1217  Optional<PostStmt> P = N->getLocationAs<PostStmt>();
1218  if (!P)
1219  return false;
1220 
1221  const DeclStmt *DS = P->getStmtAs<DeclStmt>();
1222  if (!DS)
1223  return false;
1224 
1225  if (DS->getSingleDecl() != VR->getDecl())
1226  return false;
1227 
1228  const MemSpaceRegion *VarSpace = VR->getMemorySpace();
1229  const auto *FrameSpace = dyn_cast<StackSpaceRegion>(VarSpace);
1230  if (!FrameSpace) {
1231  // If we ever directly evaluate global DeclStmts, this assertion will be
1232  // invalid, but this still seems preferable to silently accepting an
1233  // initialization that may be for a path-sensitive variable.
1234  assert(VR->getDecl()->isStaticLocal() && "non-static stackless VarRegion");
1235  return true;
1236  }
1237 
1238  assert(VR->getDecl()->hasLocalStorage());
1239  const LocationContext *LCtx = N->getLocationContext();
1240  return FrameSpace->getStackFrame() == LCtx->getStackFrame();
1241 }
1242 
1243 /// Show diagnostics for initializing or declaring a region \p R with a bad value.
1244 static void showBRDiagnostics(const char *action, llvm::raw_svector_ostream &os,
1245  const MemRegion *R, SVal V, const DeclStmt *DS) {
1246  if (R->canPrintPretty()) {
1247  R->printPretty(os);
1248  os << " ";
1249  }
1250 
1251  if (V.getAs<loc::ConcreteInt>()) {
1252  bool b = false;
1253  if (R->isBoundable()) {
1254  if (const auto *TR = dyn_cast<TypedValueRegion>(R)) {
1255  if (TR->getValueType()->isObjCObjectPointerType()) {
1256  os << action << "nil";
1257  b = true;
1258  }
1259  }
1260  }
1261  if (!b)
1262  os << action << "a null pointer value";
1263 
1264  } else if (auto CVal = V.getAs<nonloc::ConcreteInt>()) {
1265  os << action << CVal->getValue();
1266  } else if (DS) {
1267  if (V.isUndef()) {
1268  if (isa<VarRegion>(R)) {
1269  const auto *VD = cast<VarDecl>(DS->getSingleDecl());
1270  if (VD->getInit()) {
1271  os << (R->canPrintPretty() ? "initialized" : "Initializing")
1272  << " to a garbage value";
1273  } else {
1274  os << (R->canPrintPretty() ? "declared" : "Declaring")
1275  << " without an initial value";
1276  }
1277  }
1278  } else {
1279  os << (R->canPrintPretty() ? "initialized" : "Initialized")
1280  << " here";
1281  }
1282  }
1283 }
1284 
1285 /// Display diagnostics for passing bad region as a parameter.
1286 static void showBRParamDiagnostics(llvm::raw_svector_ostream& os,
1287  const VarRegion *VR,
1288  SVal V) {
1289  const auto *Param = cast<ParmVarDecl>(VR->getDecl());
1290 
1291  os << "Passing ";
1292 
1293  if (V.getAs<loc::ConcreteInt>()) {
1294  if (Param->getType()->isObjCObjectPointerType())
1295  os << "nil object reference";
1296  else
1297  os << "null pointer value";
1298  } else if (V.isUndef()) {
1299  os << "uninitialized value";
1300  } else if (auto CI = V.getAs<nonloc::ConcreteInt>()) {
1301  os << "the value " << CI->getValue();
1302  } else {
1303  os << "value";
1304  }
1305 
1306  // Printed parameter indexes are 1-based, not 0-based.
1307  unsigned Idx = Param->getFunctionScopeIndex() + 1;
1308  os << " via " << Idx << llvm::getOrdinalSuffix(Idx) << " parameter";
1309  if (VR->canPrintPretty()) {
1310  os << " ";
1311  VR->printPretty(os);
1312  }
1313 }
1314 
1315 /// Show default diagnostics for storing bad region.
1316 static void showBRDefaultDiagnostics(llvm::raw_svector_ostream &os,
1317  const MemRegion *R, SVal V) {
1318  if (V.getAs<loc::ConcreteInt>()) {
1319  bool b = false;
1320  if (R->isBoundable()) {
1321  if (const auto *TR = dyn_cast<TypedValueRegion>(R)) {
1322  if (TR->getValueType()->isObjCObjectPointerType()) {
1323  os << "nil object reference stored";
1324  b = true;
1325  }
1326  }
1327  }
1328  if (!b) {
1329  if (R->canPrintPretty())
1330  os << "Null pointer value stored";
1331  else
1332  os << "Storing null pointer value";
1333  }
1334 
1335  } else if (V.isUndef()) {
1336  if (R->canPrintPretty())
1337  os << "Uninitialized value stored";
1338  else
1339  os << "Storing uninitialized value";
1340 
1341  } else if (auto CV = V.getAs<nonloc::ConcreteInt>()) {
1342  if (R->canPrintPretty())
1343  os << "The value " << CV->getValue() << " is assigned";
1344  else
1345  os << "Assigning " << CV->getValue();
1346 
1347  } else {
1348  if (R->canPrintPretty())
1349  os << "Value assigned";
1350  else
1351  os << "Assigning value";
1352  }
1353 
1354  if (R->canPrintPretty()) {
1355  os << " to ";
1356  R->printPretty(os);
1357  }
1358 }
1359 
1361 FindLastStoreBRVisitor::VisitNode(const ExplodedNode *Succ,
1362  BugReporterContext &BRC,
1363  PathSensitiveBugReport &BR) {
1364  if (Satisfied)
1365  return nullptr;
1366 
1367  const ExplodedNode *StoreSite = nullptr;
1368  const ExplodedNode *Pred = Succ->getFirstPred();
1369  const Expr *InitE = nullptr;
1370  bool IsParam = false;
1371 
1372  // First see if we reached the declaration of the region.
1373  if (const auto *VR = dyn_cast<VarRegion>(R)) {
1374  if (isInitializationOfVar(Pred, VR)) {
1375  StoreSite = Pred;
1376  InitE = VR->getDecl()->getInit();
1377  }
1378  }
1379 
1380  // If this is a post initializer expression, initializing the region, we
1381  // should track the initializer expression.
1382  if (Optional<PostInitializer> PIP = Pred->getLocationAs<PostInitializer>()) {
1383  const MemRegion *FieldReg = (const MemRegion *)PIP->getLocationValue();
1384  if (FieldReg == R) {
1385  StoreSite = Pred;
1386  InitE = PIP->getInitializer()->getInit();
1387  }
1388  }
1389 
1390  // Otherwise, see if this is the store site:
1391  // (1) Succ has this binding and Pred does not, i.e. this is
1392  // where the binding first occurred.
1393  // (2) Succ has this binding and is a PostStore node for this region, i.e.
1394  // the same binding was re-assigned here.
1395  if (!StoreSite) {
1396  if (Succ->getState()->getSVal(R) != V)
1397  return nullptr;
1398 
1399  if (hasVisibleUpdate(Pred, Pred->getState()->getSVal(R), Succ, V)) {
1400  Optional<PostStore> PS = Succ->getLocationAs<PostStore>();
1401  if (!PS || PS->getLocationValue() != R)
1402  return nullptr;
1403  }
1404 
1405  StoreSite = Succ;
1406 
1407  // If this is an assignment expression, we can track the value
1408  // being assigned.
1409  if (Optional<PostStmt> P = Succ->getLocationAs<PostStmt>())
1410  if (const BinaryOperator *BO = P->getStmtAs<BinaryOperator>())
1411  if (BO->isAssignmentOp())
1412  InitE = BO->getRHS();
1413 
1414  // If this is a call entry, the variable should be a parameter.
1415  // FIXME: Handle CXXThisRegion as well. (This is not a priority because
1416  // 'this' should never be NULL, but this visitor isn't just for NULL and
1417  // UndefinedVal.)
1418  if (Optional<CallEnter> CE = Succ->getLocationAs<CallEnter>()) {
1419  if (const auto *VR = dyn_cast<VarRegion>(R)) {
1420 
1421  if (const auto *Param = dyn_cast<ParmVarDecl>(VR->getDecl())) {
1422  ProgramStateManager &StateMgr = BRC.getStateManager();
1423  CallEventManager &CallMgr = StateMgr.getCallEventManager();
1424 
1425  CallEventRef<> Call = CallMgr.getCaller(CE->getCalleeContext(),
1426  Succ->getState());
1427  InitE = Call->getArgExpr(Param->getFunctionScopeIndex());
1428  } else {
1429  // Handle Objective-C 'self'.
1430  assert(isa<ImplicitParamDecl>(VR->getDecl()));
1431  InitE = cast<ObjCMessageExpr>(CE->getCalleeContext()->getCallSite())
1432  ->getInstanceReceiver()->IgnoreParenCasts();
1433  }
1434  IsParam = true;
1435  }
1436  }
1437 
1438  // If this is a CXXTempObjectRegion, the Expr responsible for its creation
1439  // is wrapped inside of it.
1440  if (const auto *TmpR = dyn_cast<CXXTempObjectRegion>(R))
1441  InitE = TmpR->getExpr();
1442  }
1443 
1444  if (!StoreSite)
1445  return nullptr;
1446 
1447  Satisfied = true;
1448 
1449  // If we have an expression that provided the value, try to track where it
1450  // came from.
1451  if (InitE) {
1452  if (!IsParam)
1453  InitE = InitE->IgnoreParenCasts();
1454 
1455  bugreporter::trackExpressionValue(
1456  StoreSite, InitE, BR, TKind, EnableNullFPSuppression);
1457  }
1458 
1459  if (TKind == TrackingKind::Condition &&
1460  !OriginSFC->isParentOf(StoreSite->getStackFrame()))
1461  return nullptr;
1462 
1463  // Okay, we've found the binding. Emit an appropriate message.
1464  SmallString<256> sbuf;
1465  llvm::raw_svector_ostream os(sbuf);
1466 
1467  if (Optional<PostStmt> PS = StoreSite->getLocationAs<PostStmt>()) {
1468  const Stmt *S = PS->getStmt();
1469  const char *action = nullptr;
1470  const auto *DS = dyn_cast<DeclStmt>(S);
1471  const auto *VR = dyn_cast<VarRegion>(R);
1472 
1473  if (DS) {
1474  action = R->canPrintPretty() ? "initialized to " :
1475  "Initializing to ";
1476  } else if (isa<BlockExpr>(S)) {
1477  action = R->canPrintPretty() ? "captured by block as " :
1478  "Captured by block as ";
1479  if (VR) {
1480  // See if we can get the BlockVarRegion.
1481  ProgramStateRef State = StoreSite->getState();
1482  SVal V = StoreSite->getSVal(S);
1483  if (const auto *BDR =
1484  dyn_cast_or_null<BlockDataRegion>(V.getAsRegion())) {
1485  if (const VarRegion *OriginalR = BDR->getOriginalRegion(VR)) {
1486  if (auto KV = State->getSVal(OriginalR).getAs<KnownSVal>())
1487  BR.addVisitor(std::make_unique<FindLastStoreBRVisitor>(
1488  *KV, OriginalR, EnableNullFPSuppression, TKind, OriginSFC));
1489  }
1490  }
1491  }
1492  }
1493  if (action)
1494  showBRDiagnostics(action, os, R, V, DS);
1495 
1496  } else if (StoreSite->getLocation().getAs<CallEnter>()) {
1497  if (const auto *VR = dyn_cast<VarRegion>(R))
1498  showBRParamDiagnostics(os, VR, V);
1499  }
1500 
1501  if (os.str().empty())
1502  showBRDefaultDiagnostics(os, R, V);
1503 
1504  if (TKind == bugreporter::TrackingKind::Condition)
1506 
1507  // Construct a new PathDiagnosticPiece.
1508  ProgramPoint P = StoreSite->getLocation();
1509  PathDiagnosticLocation L;
1510  if (P.getAs<CallEnter>() && InitE)
1511  L = PathDiagnosticLocation(InitE, BRC.getSourceManager(),
1512  P.getLocationContext());
1513 
1514  if (!L.isValid() || !L.asLocation().isValid())
1515  L = PathDiagnosticLocation::create(P, BRC.getSourceManager());
1516 
1517  if (!L.isValid() || !L.asLocation().isValid())
1518  return nullptr;
1519 
1520  return std::make_shared<PathDiagnosticEventPiece>(L, os.str());
1521 }
1522 
1523 //===----------------------------------------------------------------------===//
1524 // Implementation of TrackConstraintBRVisitor.
1525 //===----------------------------------------------------------------------===//
1526 
1527 void TrackConstraintBRVisitor::Profile(llvm::FoldingSetNodeID &ID) const {
1528  static int tag = 0;
1529  ID.AddPointer(&tag);
1530  ID.AddBoolean(Assumption);
1531  ID.Add(Constraint);
1532 }
1533 
1534 /// Return the tag associated with this visitor. This tag will be used
1535 /// to make all PathDiagnosticPieces created by this visitor.
1536 const char *TrackConstraintBRVisitor::getTag() {
1537  return "TrackConstraintBRVisitor";
1538 }
1539 
1540 bool TrackConstraintBRVisitor::isUnderconstrained(const ExplodedNode *N) const {
1541  if (IsZeroCheck)
1542  return N->getState()->isNull(Constraint).isUnderconstrained();
1543  return (bool)N->getState()->assume(Constraint, !Assumption);
1544 }
1545 
1546 PathDiagnosticPieceRef TrackConstraintBRVisitor::VisitNode(
1547  const ExplodedNode *N, BugReporterContext &BRC, PathSensitiveBugReport &) {
1548  const ExplodedNode *PrevN = N->getFirstPred();
1549  if (IsSatisfied)
1550  return nullptr;
1551 
1552  // Start tracking after we see the first state in which the value is
1553  // constrained.
1554  if (!IsTrackingTurnedOn)
1555  if (!isUnderconstrained(N))
1556  IsTrackingTurnedOn = true;
1557  if (!IsTrackingTurnedOn)
1558  return nullptr;
1559 
1560  // Check if in the previous state it was feasible for this constraint
1561  // to *not* be true.
1562  if (isUnderconstrained(PrevN)) {
1563  IsSatisfied = true;
1564 
1565  // As a sanity check, make sure that the negation of the constraint
1566  // was infeasible in the current state. If it is feasible, we somehow
1567  // missed the transition point.
1568  assert(!isUnderconstrained(N));
1569 
1570  // We found the transition point for the constraint. We now need to
1571  // pretty-print the constraint. (work-in-progress)
1572  SmallString<64> sbuf;
1573  llvm::raw_svector_ostream os(sbuf);
1574 
1575  if (Constraint.getAs<Loc>()) {
1576  os << "Assuming pointer value is ";
1577  os << (Assumption ? "non-null" : "null");
1578  }
1579 
1580  if (os.str().empty())
1581  return nullptr;
1582 
1583  // Construct a new PathDiagnosticPiece.
1584  ProgramPoint P = N->getLocation();
1585  PathDiagnosticLocation L =
1586  PathDiagnosticLocation::create(P, BRC.getSourceManager());
1587  if (!L.isValid())
1588  return nullptr;
1589 
1590  auto X = std::make_shared<PathDiagnosticEventPiece>(L, os.str());
1591  X->setTag(getTag());
1592  return std::move(X);
1593  }
1594 
1595  return nullptr;
1596 }
1597 
1598 //===----------------------------------------------------------------------===//
1599 // Implementation of SuppressInlineDefensiveChecksVisitor.
1600 //===----------------------------------------------------------------------===//
1601 
1602 SuppressInlineDefensiveChecksVisitor::
1603 SuppressInlineDefensiveChecksVisitor(DefinedSVal Value, const ExplodedNode *N)
1604  : V(Value) {
1605  // Check if the visitor is disabled.
1606  AnalyzerOptions &Options = N->getState()->getAnalysisManager().options;
1607  if (!Options.ShouldSuppressInlinedDefensiveChecks)
1608  IsSatisfied = true;
1609 
1610  assert(N->getState()->isNull(V).isConstrainedTrue() &&
1611  "The visitor only tracks the cases where V is constrained to 0");
1612 }
1613 
1614 void SuppressInlineDefensiveChecksVisitor::Profile(
1615  llvm::FoldingSetNodeID &ID) const {
1616  static int id = 0;
1617  ID.AddPointer(&id);
1618  ID.Add(V);
1619 }
1620 
1621 const char *SuppressInlineDefensiveChecksVisitor::getTag() {
1622  return "IDCVisitor";
1623 }
1624 
1626 SuppressInlineDefensiveChecksVisitor::VisitNode(const ExplodedNode *Succ,
1627  BugReporterContext &BRC,
1628  PathSensitiveBugReport &BR) {
1629  const ExplodedNode *Pred = Succ->getFirstPred();
1630  if (IsSatisfied)
1631  return nullptr;
1632 
1633  // Start tracking after we see the first state in which the value is null.
1634  if (!IsTrackingTurnedOn)
1635  if (Succ->getState()->isNull(V).isConstrainedTrue())
1636  IsTrackingTurnedOn = true;
1637  if (!IsTrackingTurnedOn)
1638  return nullptr;
1639 
1640  // Check if in the previous state it was feasible for this value
1641  // to *not* be null.
1642  if (!Pred->getState()->isNull(V).isConstrainedTrue()) {
1643  IsSatisfied = true;
1644 
1645  assert(Succ->getState()->isNull(V).isConstrainedTrue());
1646 
1647  // Check if this is inlined defensive checks.
1648  const LocationContext *CurLC =Succ->getLocationContext();
1649  const LocationContext *ReportLC = BR.getErrorNode()->getLocationContext();
1650  if (CurLC != ReportLC && !CurLC->isParentOf(ReportLC)) {
1651  BR.markInvalid("Suppress IDC", CurLC);
1652  return nullptr;
1653  }
1654 
1655  // Treat defensive checks in function-like macros as if they were an inlined
1656  // defensive check. If the bug location is not in a macro and the
1657  // terminator for the current location is in a macro then suppress the
1658  // warning.
1659  auto BugPoint = BR.getErrorNode()->getLocation().getAs<StmtPoint>();
1660 
1661  if (!BugPoint)
1662  return nullptr;
1663 
1664  ProgramPoint CurPoint = Succ->getLocation();
1665  const Stmt *CurTerminatorStmt = nullptr;
1666  if (auto BE = CurPoint.getAs<BlockEdge>()) {
1667  CurTerminatorStmt = BE->getSrc()->getTerminator().getStmt();
1668  } else if (auto SP = CurPoint.getAs<StmtPoint>()) {
1669  const Stmt *CurStmt = SP->getStmt();
1670  if (!CurStmt->getBeginLoc().isMacroID())
1671  return nullptr;
1672 
1673  CFGStmtMap *Map = CurLC->getAnalysisDeclContext()->getCFGStmtMap();
1674  CurTerminatorStmt = Map->getBlock(CurStmt)->getTerminatorStmt();
1675  } else {
1676  return nullptr;
1677  }
1678 
1679  if (!CurTerminatorStmt)
1680  return nullptr;
1681 
1682  SourceLocation TerminatorLoc = CurTerminatorStmt->getBeginLoc();
1683  if (TerminatorLoc.isMacroID()) {
1684  SourceLocation BugLoc = BugPoint->getStmt()->getBeginLoc();
1685 
1686  // Suppress reports unless we are in that same macro.
1687  if (!BugLoc.isMacroID() ||
1688  getMacroName(BugLoc, BRC) != getMacroName(TerminatorLoc, BRC)) {
1689  BR.markInvalid("Suppress Macro IDC", CurLC);
1690  }
1691  return nullptr;
1692  }
1693  }
1694  return nullptr;
1695 }
1696 
1697 //===----------------------------------------------------------------------===//
1698 // TrackControlDependencyCondBRVisitor.
1699 //===----------------------------------------------------------------------===//
1700 
1701 namespace {
1702 /// Tracks the expressions that are a control dependency of the node that was
1703 /// supplied to the constructor.
1704 /// For example:
1705 ///
1706 /// cond = 1;
1707 /// if (cond)
1708 /// 10 / 0;
1709 ///
1710 /// An error is emitted at line 3. This visitor realizes that the branch
1711 /// on line 2 is a control dependency of line 3, and tracks it's condition via
1712 /// trackExpressionValue().
1713 class TrackControlDependencyCondBRVisitor final : public BugReporterVisitor {
1714  const ExplodedNode *Origin;
1715  ControlDependencyCalculator ControlDeps;
1716  llvm::SmallSet<const CFGBlock *, 32> VisitedBlocks;
1717 
1718 public:
1719  TrackControlDependencyCondBRVisitor(const ExplodedNode *O)
1720  : Origin(O), ControlDeps(&O->getCFG()) {}
1721 
1722  void Profile(llvm::FoldingSetNodeID &ID) const override {
1723  static int x = 0;
1724  ID.AddPointer(&x);
1725  }
1726 
1727  PathDiagnosticPieceRef VisitNode(const ExplodedNode *N,
1728  BugReporterContext &BRC,
1729  PathSensitiveBugReport &BR) override;
1730 };
1731 } // end of anonymous namespace
1732 
1733 static std::shared_ptr<PathDiagnosticEventPiece>
1735  const ExplodedNode *N,
1736  BugReporterContext &BRC) {
1737 
1738  if (BRC.getAnalyzerOptions().AnalysisDiagOpt == PD_NONE ||
1739  !BRC.getAnalyzerOptions().ShouldTrackConditionsDebug)
1740  return nullptr;
1741 
1742  std::string ConditionText = Lexer::getSourceText(
1744  BRC.getSourceManager(),
1745  BRC.getASTContext().getLangOpts());
1746 
1747  return std::make_shared<PathDiagnosticEventPiece>(
1749  Cond, BRC.getSourceManager(), N->getLocationContext()),
1750  (Twine() + "Tracking condition '" + ConditionText + "'").str());
1751 }
1752 
1753 static bool isAssertlikeBlock(const CFGBlock *B, ASTContext &Context) {
1754  if (B->succ_size() != 2)
1755  return false;
1756 
1757  const CFGBlock *Then = B->succ_begin()->getReachableBlock();
1758  const CFGBlock *Else = (B->succ_begin() + 1)->getReachableBlock();
1759 
1760  if (!Then || !Else)
1761  return false;
1762 
1763  if (Then->isInevitablySinking() != Else->isInevitablySinking())
1764  return true;
1765 
1766  // For the following condition the following CFG would be built:
1767  //
1768  // ------------->
1769  // / \
1770  // [B1] -> [B2] -> [B3] -> [sink]
1771  // assert(A && B || C); \ \
1772  // -----------> [go on with the execution]
1773  //
1774  // It so happens that CFGBlock::getTerminatorCondition returns 'A' for block
1775  // B1, 'A && B' for B2, and 'A && B || C' for B3. Let's check whether we
1776  // reached the end of the condition!
1777  if (const Stmt *ElseCond = Else->getTerminatorCondition())
1778  if (const auto *BinOp = dyn_cast<BinaryOperator>(ElseCond))
1779  if (BinOp->isLogicalOp())
1780  return isAssertlikeBlock(Else, Context);
1781 
1782  return false;
1783 }
1784 
1786 TrackControlDependencyCondBRVisitor::VisitNode(const ExplodedNode *N,
1787  BugReporterContext &BRC,
1788  PathSensitiveBugReport &BR) {
1789  // We can only reason about control dependencies within the same stack frame.
1790  if (Origin->getStackFrame() != N->getStackFrame())
1791  return nullptr;
1792 
1793  CFGBlock *NB = const_cast<CFGBlock *>(N->getCFGBlock());
1794 
1795  // Skip if we already inspected this block.
1796  if (!VisitedBlocks.insert(NB).second)
1797  return nullptr;
1798 
1799  CFGBlock *OriginB = const_cast<CFGBlock *>(Origin->getCFGBlock());
1800 
1801  // TODO: Cache CFGBlocks for each ExplodedNode.
1802  if (!OriginB || !NB)
1803  return nullptr;
1804 
1805  if (isAssertlikeBlock(NB, BRC.getASTContext()))
1806  return nullptr;
1807 
1808  if (ControlDeps.isControlDependent(OriginB, NB)) {
1809  // We don't really want to explain for range loops. Evidence suggests that
1810  // the only thing that leads to is the addition of calls to operator!=.
1811  if (llvm::isa_and_nonnull<CXXForRangeStmt>(NB->getTerminatorStmt()))
1812  return nullptr;
1813 
1814  if (const Expr *Condition = NB->getLastCondition()) {
1815  // Keeping track of the already tracked conditions on a visitor level
1816  // isn't sufficient, because a new visitor is created for each tracked
1817  // expression, hence the BugReport level set.
1818  if (BR.addTrackedCondition(N)) {
1819  bugreporter::trackExpressionValue(
1820  N, Condition, BR, bugreporter::TrackingKind::Condition,
1821  /*EnableNullFPSuppression=*/false);
1822  return constructDebugPieceForTrackedCondition(Condition, N, BRC);
1823  }
1824  }
1825  }
1826 
1827  return nullptr;
1828 }
1829 
1830 //===----------------------------------------------------------------------===//
1831 // Implementation of trackExpressionValue.
1832 //===----------------------------------------------------------------------===//
1833 
1834 static const MemRegion *getLocationRegionIfReference(const Expr *E,
1835  const ExplodedNode *N) {
1836  if (const auto *DR = dyn_cast<DeclRefExpr>(E)) {
1837  if (const auto *VD = dyn_cast<VarDecl>(DR->getDecl())) {
1838  if (!VD->getType()->isReferenceType())
1839  return nullptr;
1840  ProgramStateManager &StateMgr = N->getState()->getStateManager();
1841  MemRegionManager &MRMgr = StateMgr.getRegionManager();
1842  return MRMgr.getVarRegion(VD, N->getLocationContext());
1843  }
1844  }
1845 
1846  // FIXME: This does not handle other kinds of null references,
1847  // for example, references from FieldRegions:
1848  // struct Wrapper { int &ref; };
1849  // Wrapper w = { *(int *)0 };
1850  // w.ref = 1;
1851 
1852  return nullptr;
1853 }
1854 
1855 /// \return A subexpression of {@code Ex} which represents the
1856 /// expression-of-interest.
1857 static const Expr *peelOffOuterExpr(const Expr *Ex,
1858  const ExplodedNode *N) {
1859  Ex = Ex->IgnoreParenCasts();
1860  if (const auto *FE = dyn_cast<FullExpr>(Ex))
1861  return peelOffOuterExpr(FE->getSubExpr(), N);
1862  if (const auto *OVE = dyn_cast<OpaqueValueExpr>(Ex))
1863  return peelOffOuterExpr(OVE->getSourceExpr(), N);
1864  if (const auto *POE = dyn_cast<PseudoObjectExpr>(Ex)) {
1865  const auto *PropRef = dyn_cast<ObjCPropertyRefExpr>(POE->getSyntacticForm());
1866  if (PropRef && PropRef->isMessagingGetter()) {
1867  const Expr *GetterMessageSend =
1868  POE->getSemanticExpr(POE->getNumSemanticExprs() - 1);
1869  assert(isa<ObjCMessageExpr>(GetterMessageSend->IgnoreParenCasts()));
1870  return peelOffOuterExpr(GetterMessageSend, N);
1871  }
1872  }
1873 
1874  // Peel off the ternary operator.
1875  if (const auto *CO = dyn_cast<ConditionalOperator>(Ex)) {
1876  // Find a node where the branching occurred and find out which branch
1877  // we took (true/false) by looking at the ExplodedGraph.
1878  const ExplodedNode *NI = N;
1879  do {
1880  ProgramPoint ProgPoint = NI->getLocation();
1881  if (Optional<BlockEdge> BE = ProgPoint.getAs<BlockEdge>()) {
1882  const CFGBlock *srcBlk = BE->getSrc();
1883  if (const Stmt *term = srcBlk->getTerminatorStmt()) {
1884  if (term == CO) {
1885  bool TookTrueBranch = (*(srcBlk->succ_begin()) == BE->getDst());
1886  if (TookTrueBranch)
1887  return peelOffOuterExpr(CO->getTrueExpr(), N);
1888  else
1889  return peelOffOuterExpr(CO->getFalseExpr(), N);
1890  }
1891  }
1892  }
1893  NI = NI->getFirstPred();
1894  } while (NI);
1895  }
1896 
1897  if (auto *BO = dyn_cast<BinaryOperator>(Ex))
1898  if (const Expr *SubEx = peelOffPointerArithmetic(BO))
1899  return peelOffOuterExpr(SubEx, N);
1900 
1901  if (auto *UO = dyn_cast<UnaryOperator>(Ex)) {
1902  if (UO->getOpcode() == UO_LNot)
1903  return peelOffOuterExpr(UO->getSubExpr(), N);
1904 
1905  // FIXME: There's a hack in our Store implementation that always computes
1906  // field offsets around null pointers as if they are always equal to 0.
1907  // The idea here is to report accesses to fields as null dereferences
1908  // even though the pointer value that's being dereferenced is actually
1909  // the offset of the field rather than exactly 0.
1910  // See the FIXME in StoreManager's getLValueFieldOrIvar() method.
1911  // This code interacts heavily with this hack; otherwise the value
1912  // would not be null at all for most fields, so we'd be unable to track it.
1913  if (UO->getOpcode() == UO_AddrOf && UO->getSubExpr()->isLValue())
1914  if (const Expr *DerefEx = bugreporter::getDerefExpr(UO->getSubExpr()))
1915  return peelOffOuterExpr(DerefEx, N);
1916  }
1917 
1918  return Ex;
1919 }
1920 
1921 /// Find the ExplodedNode where the lvalue (the value of 'Ex')
1922 /// was computed.
1923 static const ExplodedNode* findNodeForExpression(const ExplodedNode *N,
1924  const Expr *Inner) {
1925  while (N) {
1926  if (N->getStmtForDiagnostics() == Inner)
1927  return N;
1928  N = N->getFirstPred();
1929  }
1930  return N;
1931 }
1932 
1933 bool bugreporter::trackExpressionValue(const ExplodedNode *InputNode,
1934  const Expr *E,
1935  PathSensitiveBugReport &report,
1936  bugreporter::TrackingKind TKind,
1937  bool EnableNullFPSuppression) {
1938 
1939  if (!E || !InputNode)
1940  return false;
1941 
1942  const Expr *Inner = peelOffOuterExpr(E, InputNode);
1943  const ExplodedNode *LVNode = findNodeForExpression(InputNode, Inner);
1944  if (!LVNode)
1945  return false;
1946 
1947  ProgramStateRef LVState = LVNode->getState();
1948  const StackFrameContext *SFC = LVNode->getStackFrame();
1949 
1950  // We only track expressions if we believe that they are important. Chances
1951  // are good that control dependencies to the tracking point are also improtant
1952  // because of this, let's explain why we believe control reached this point.
1953  // TODO: Shouldn't we track control dependencies of every bug location, rather
1954  // than only tracked expressions?
1955  if (LVState->getAnalysisManager().getAnalyzerOptions().ShouldTrackConditions)
1956  report.addVisitor(std::make_unique<TrackControlDependencyCondBRVisitor>(
1957  InputNode));
1958 
1959  // The message send could be nil due to the receiver being nil.
1960  // At this point in the path, the receiver should be live since we are at the
1961  // message send expr. If it is nil, start tracking it.
1962  if (const Expr *Receiver = NilReceiverBRVisitor::getNilReceiver(Inner, LVNode))
1963  trackExpressionValue(
1964  LVNode, Receiver, report, TKind, EnableNullFPSuppression);
1965 
1966  // Track the index if this is an array subscript.
1967  if (const auto *Arr = dyn_cast<ArraySubscriptExpr>(Inner))
1968  trackExpressionValue(
1969  LVNode, Arr->getIdx(), report, TKind, /*EnableNullFPSuppression*/false);
1970 
1971  // See if the expression we're interested refers to a variable.
1972  // If so, we can track both its contents and constraints on its value.
1974  SVal LVal = LVNode->getSVal(Inner);
1975 
1976  const MemRegion *RR = getLocationRegionIfReference(Inner, LVNode);
1977  bool LVIsNull = LVState->isNull(LVal).isConstrainedTrue();
1978 
1979  // If this is a C++ reference to a null pointer, we are tracking the
1980  // pointer. In addition, we should find the store at which the reference
1981  // got initialized.
1982  if (RR && !LVIsNull)
1983  if (auto KV = LVal.getAs<KnownSVal>())
1984  report.addVisitor(std::make_unique<FindLastStoreBRVisitor>(
1985  *KV, RR, EnableNullFPSuppression, TKind, SFC));
1986 
1987  // In case of C++ references, we want to differentiate between a null
1988  // reference and reference to null pointer.
1989  // If the LVal is null, check if we are dealing with null reference.
1990  // For those, we want to track the location of the reference.
1991  const MemRegion *R = (RR && LVIsNull) ? RR :
1992  LVNode->getSVal(Inner).getAsRegion();
1993 
1994  if (R) {
1995 
1996  // Mark both the variable region and its contents as interesting.
1997  SVal V = LVState->getRawSVal(loc::MemRegionVal(R));
1998  report.addVisitor(
1999  std::make_unique<NoStoreFuncVisitor>(cast<SubRegion>(R), TKind));
2000 
2001  MacroNullReturnSuppressionVisitor::addMacroVisitorIfNecessary(
2002  LVNode, R, EnableNullFPSuppression, report, V);
2003 
2004  report.markInteresting(V, TKind);
2005  report.addVisitor(std::make_unique<UndefOrNullArgVisitor>(R));
2006 
2007  // If the contents are symbolic and null, find out when they became null.
2008  if (V.getAsLocSymbol(/*IncludeBaseRegions=*/true))
2009  if (LVState->isNull(V).isConstrainedTrue())
2010  report.addVisitor(std::make_unique<TrackConstraintBRVisitor>(
2011  V.castAs<DefinedSVal>(), false));
2012 
2013  // Add visitor, which will suppress inline defensive checks.
2014  if (auto DV = V.getAs<DefinedSVal>())
2015  if (!DV->isZeroConstant() && LVState->isNull(*DV).isConstrainedTrue() &&
2016  EnableNullFPSuppression)
2017  report.addVisitor(
2018  std::make_unique<SuppressInlineDefensiveChecksVisitor>(*DV,
2019  LVNode));
2020 
2021  if (auto KV = V.getAs<KnownSVal>())
2022  report.addVisitor(std::make_unique<FindLastStoreBRVisitor>(
2023  *KV, R, EnableNullFPSuppression, TKind, SFC));
2024  return true;
2025  }
2026  }
2027 
2028  // If the expression is not an "lvalue expression", we can still
2029  // track the constraints on its contents.
2030  SVal V = LVState->getSValAsScalarOrLoc(Inner, LVNode->getLocationContext());
2031 
2032  ReturnVisitor::addVisitorIfNecessary(
2033  LVNode, Inner, report, EnableNullFPSuppression, TKind);
2034 
2035  // Is it a symbolic value?
2036  if (auto L = V.getAs<loc::MemRegionVal>()) {
2037  // FIXME: this is a hack for fixing a later crash when attempting to
2038  // dereference a void* pointer.
2039  // We should not try to dereference pointers at all when we don't care
2040  // what is written inside the pointer.
2041  bool CanDereference = true;
2042  if (const auto *SR = L->getRegionAs<SymbolicRegion>()) {
2043  if (SR->getSymbol()->getType()->getPointeeType()->isVoidType())
2044  CanDereference = false;
2045  } else if (L->getRegionAs<AllocaRegion>())
2046  CanDereference = false;
2047 
2048  // At this point we are dealing with the region's LValue.
2049  // However, if the rvalue is a symbolic region, we should track it as well.
2050  // Try to use the correct type when looking up the value.
2051  SVal RVal;
2053  RVal = LVState->getRawSVal(L.getValue(), Inner->getType());
2054  else if (CanDereference)
2055  RVal = LVState->getSVal(L->getRegion());
2056 
2057  if (CanDereference) {
2058  report.addVisitor(
2059  std::make_unique<UndefOrNullArgVisitor>(L->getRegion()));
2060 
2061  if (auto KV = RVal.getAs<KnownSVal>())
2062  report.addVisitor(std::make_unique<FindLastStoreBRVisitor>(
2063  *KV, L->getRegion(), EnableNullFPSuppression, TKind, SFC));
2064  }
2065 
2066  const MemRegion *RegionRVal = RVal.getAsRegion();
2067  if (RegionRVal && isa<SymbolicRegion>(RegionRVal)) {
2068  report.markInteresting(RegionRVal, TKind);
2069  report.addVisitor(std::make_unique<TrackConstraintBRVisitor>(
2070  loc::MemRegionVal(RegionRVal), /*assumption=*/false));
2071  }
2072  }
2073  return true;
2074 }
2075 
2076 //===----------------------------------------------------------------------===//
2077 // Implementation of NulReceiverBRVisitor.
2078 //===----------------------------------------------------------------------===//
2079 
2080 const Expr *NilReceiverBRVisitor::getNilReceiver(const Stmt *S,
2081  const ExplodedNode *N) {
2082  const auto *ME = dyn_cast<ObjCMessageExpr>(S);
2083  if (!ME)
2084  return nullptr;
2085  if (const Expr *Receiver = ME->getInstanceReceiver()) {
2086  ProgramStateRef state = N->getState();
2087  SVal V = N->getSVal(Receiver);
2088  if (state->isNull(V).isConstrainedTrue())
2089  return Receiver;
2090  }
2091  return nullptr;
2092 }
2093 
2095 NilReceiverBRVisitor::VisitNode(const ExplodedNode *N, BugReporterContext &BRC,
2096  PathSensitiveBugReport &BR) {
2097  Optional<PreStmt> P = N->getLocationAs<PreStmt>();
2098  if (!P)
2099  return nullptr;
2100 
2101  const Stmt *S = P->getStmt();
2102  const Expr *Receiver = getNilReceiver(S, N);
2103  if (!Receiver)
2104  return nullptr;
2105 
2107  llvm::raw_svector_ostream OS(Buf);
2108 
2109  if (const auto *ME = dyn_cast<ObjCMessageExpr>(S)) {
2110  OS << "'";
2111  ME->getSelector().print(OS);
2112  OS << "' not called";
2113  }
2114  else {
2115  OS << "No method is called";
2116  }
2117  OS << " because the receiver is nil";
2118 
2119  // The receiver was nil, and hence the method was skipped.
2120  // Register a BugReporterVisitor to issue a message telling us how
2121  // the receiver was null.
2122  bugreporter::trackExpressionValue(
2123  N, Receiver, BR, bugreporter::TrackingKind::Thorough,
2124  /*EnableNullFPSuppression*/ false);
2125  // Issue a message saying that the method was skipped.
2126  PathDiagnosticLocation L(Receiver, BRC.getSourceManager(),
2127  N->getLocationContext());
2128  return std::make_shared<PathDiagnosticEventPiece>(L, OS.str());
2129 }
2130 
2131 //===----------------------------------------------------------------------===//
2132 // Visitor that tries to report interesting diagnostics from conditions.
2133 //===----------------------------------------------------------------------===//
2134 
2135 /// Return the tag associated with this visitor. This tag will be used
2136 /// to make all PathDiagnosticPieces created by this visitor.
2137 const char *ConditionBRVisitor::getTag() { return "ConditionBRVisitor"; }
2138 
2140 ConditionBRVisitor::VisitNode(const ExplodedNode *N, BugReporterContext &BRC,
2141  PathSensitiveBugReport &BR) {
2142  auto piece = VisitNodeImpl(N, BRC, BR);
2143  if (piece) {
2144  piece->setTag(getTag());
2145  if (auto *ev = dyn_cast<PathDiagnosticEventPiece>(piece.get()))
2146  ev->setPrunable(true, /* override */ false);
2147  }
2148  return piece;
2149 }
2150 
2152 ConditionBRVisitor::VisitNodeImpl(const ExplodedNode *N,
2153  BugReporterContext &BRC,
2154  PathSensitiveBugReport &BR) {
2155  ProgramPoint ProgPoint = N->getLocation();
2156  const std::pair<const ProgramPointTag *, const ProgramPointTag *> &Tags =
2158 
2159  // If an assumption was made on a branch, it should be caught
2160  // here by looking at the state transition.
2161  if (Optional<BlockEdge> BE = ProgPoint.getAs<BlockEdge>()) {
2162  const CFGBlock *SrcBlock = BE->getSrc();
2163  if (const Stmt *Term = SrcBlock->getTerminatorStmt()) {
2164  // If the tag of the previous node is 'Eagerly Assume...' the current
2165  // 'BlockEdge' has the same constraint information. We do not want to
2166  // report the value as it is just an assumption on the predecessor node
2167  // which will be caught in the next VisitNode() iteration as a 'PostStmt'.
2168  const ProgramPointTag *PreviousNodeTag =
2169  N->getFirstPred()->getLocation().getTag();
2170  if (PreviousNodeTag == Tags.first || PreviousNodeTag == Tags.second)
2171  return nullptr;
2172 
2173  return VisitTerminator(Term, N, SrcBlock, BE->getDst(), BR, BRC);
2174  }
2175  return nullptr;
2176  }
2177 
2178  if (Optional<PostStmt> PS = ProgPoint.getAs<PostStmt>()) {
2179  const ProgramPointTag *CurrentNodeTag = PS->getTag();
2180  if (CurrentNodeTag != Tags.first && CurrentNodeTag != Tags.second)
2181  return nullptr;
2182 
2183  bool TookTrue = CurrentNodeTag == Tags.first;
2184  return VisitTrueTest(cast<Expr>(PS->getStmt()), BRC, BR, N, TookTrue);
2185  }
2186 
2187  return nullptr;
2188 }
2189 
2190 PathDiagnosticPieceRef ConditionBRVisitor::VisitTerminator(
2191  const Stmt *Term, const ExplodedNode *N, const CFGBlock *srcBlk,
2192  const CFGBlock *dstBlk, PathSensitiveBugReport &R,
2193  BugReporterContext &BRC) {
2194  const Expr *Cond = nullptr;
2195 
2196  // In the code below, Term is a CFG terminator and Cond is a branch condition
2197  // expression upon which the decision is made on this terminator.
2198  //
2199  // For example, in "if (x == 0)", the "if (x == 0)" statement is a terminator,
2200  // and "x == 0" is the respective condition.
2201  //
2202  // Another example: in "if (x && y)", we've got two terminators and two
2203  // conditions due to short-circuit nature of operator "&&":
2204  // 1. The "if (x && y)" statement is a terminator,
2205  // and "y" is the respective condition.
2206  // 2. Also "x && ..." is another terminator,
2207  // and "x" is its condition.
2208 
2209  switch (Term->getStmtClass()) {
2210  // FIXME: Stmt::SwitchStmtClass is worth handling, however it is a bit
2211  // more tricky because there are more than two branches to account for.
2212  default:
2213  return nullptr;
2214  case Stmt::IfStmtClass:
2215  Cond = cast<IfStmt>(Term)->getCond();
2216  break;
2217  case Stmt::ConditionalOperatorClass:
2218  Cond = cast<ConditionalOperator>(Term)->getCond();
2219  break;
2220  case Stmt::BinaryOperatorClass:
2221  // When we encounter a logical operator (&& or ||) as a CFG terminator,
2222  // then the condition is actually its LHS; otherwise, we'd encounter
2223  // the parent, such as if-statement, as a terminator.
2224  const auto *BO = cast<BinaryOperator>(Term);
2225  assert(BO->isLogicalOp() &&
2226  "CFG terminator is not a short-circuit operator!");
2227  Cond = BO->getLHS();
2228  break;
2229  }
2230 
2231  Cond = Cond->IgnoreParens();
2232 
2233  // However, when we encounter a logical operator as a branch condition,
2234  // then the condition is actually its RHS, because LHS would be
2235  // the condition for the logical operator terminator.
2236  while (const auto *InnerBO = dyn_cast<BinaryOperator>(Cond)) {
2237  if (!InnerBO->isLogicalOp())
2238  break;
2239  Cond = InnerBO->getRHS()->IgnoreParens();
2240  }
2241 
2242  assert(Cond);
2243  assert(srcBlk->succ_size() == 2);
2244  const bool TookTrue = *(srcBlk->succ_begin()) == dstBlk;
2245  return VisitTrueTest(Cond, BRC, R, N, TookTrue);
2246 }
2247 
2249 ConditionBRVisitor::VisitTrueTest(const Expr *Cond, BugReporterContext &BRC,
2250  PathSensitiveBugReport &R,
2251  const ExplodedNode *N, bool TookTrue) {
2252  ProgramStateRef CurrentState = N->getState();
2253  ProgramStateRef PrevState = N->getFirstPred()->getState();
2254  const LocationContext *LCtx = N->getLocationContext();
2255 
2256  // If the constraint information is changed between the current and the
2257  // previous program state we assuming the newly seen constraint information.
2258  // If we cannot evaluate the condition (and the constraints are the same)
2259  // the analyzer has no information about the value and just assuming it.
2260  bool IsAssuming =
2261  !BRC.getStateManager().haveEqualConstraints(CurrentState, PrevState) ||
2262  CurrentState->getSVal(Cond, LCtx).isUnknownOrUndef();
2263 
2264  // These will be modified in code below, but we need to preserve the original
2265  // values in case we want to throw the generic message.
2266  const Expr *CondTmp = Cond;
2267  bool TookTrueTmp = TookTrue;
2268 
2269  while (true) {
2270  CondTmp = CondTmp->IgnoreParenCasts();
2271  switch (CondTmp->getStmtClass()) {
2272  default:
2273  break;
2274  case Stmt::BinaryOperatorClass:
2275  if (auto P = VisitTrueTest(Cond, cast<BinaryOperator>(CondTmp),
2276  BRC, R, N, TookTrueTmp, IsAssuming))
2277  return P;
2278  break;
2279  case Stmt::DeclRefExprClass:
2280  if (auto P = VisitTrueTest(Cond, cast<DeclRefExpr>(CondTmp),
2281  BRC, R, N, TookTrueTmp, IsAssuming))
2282  return P;
2283  break;
2284  case Stmt::MemberExprClass:
2285  if (auto P = VisitTrueTest(Cond, cast<MemberExpr>(CondTmp),
2286  BRC, R, N, TookTrueTmp, IsAssuming))
2287  return P;
2288  break;
2289  case Stmt::UnaryOperatorClass: {
2290  const auto *UO = cast<UnaryOperator>(CondTmp);
2291  if (UO->getOpcode() == UO_LNot) {
2292  TookTrueTmp = !TookTrueTmp;
2293  CondTmp = UO->getSubExpr();
2294  continue;
2295  }
2296  break;
2297  }
2298  }
2299  break;
2300  }
2301 
2302  // Condition too complex to explain? Just say something so that the user
2303  // knew we've made some path decision at this point.
2304  // If it is too complex and we know the evaluation of the condition do not
2305  // repeat the note from 'BugReporter.cpp'
2306  if (!IsAssuming)
2307  return nullptr;
2308 
2309  PathDiagnosticLocation Loc(Cond, BRC.getSourceManager(), LCtx);
2310  if (!Loc.isValid() || !Loc.asLocation().isValid())
2311  return nullptr;
2312 
2313  return std::make_shared<PathDiagnosticEventPiece>(
2314  Loc, TookTrue ? GenericTrueMessage : GenericFalseMessage);
2315 }
2316 
2317 bool ConditionBRVisitor::patternMatch(const Expr *Ex,
2318  const Expr *ParentEx,
2319  raw_ostream &Out,
2320  BugReporterContext &BRC,
2321  PathSensitiveBugReport &report,
2322  const ExplodedNode *N,
2323  Optional<bool> &prunable,
2324  bool IsSameFieldName) {
2325  const Expr *OriginalExpr = Ex;
2326  Ex = Ex->IgnoreParenCasts();
2327 
2328  if (isa<GNUNullExpr>(Ex) || isa<ObjCBoolLiteralExpr>(Ex) ||
2329  isa<CXXBoolLiteralExpr>(Ex) || isa<IntegerLiteral>(Ex) ||
2330  isa<FloatingLiteral>(Ex)) {
2331  // Use heuristics to determine if the expression is a macro
2332  // expanding to a literal and if so, use the macro's name.
2333  SourceLocation BeginLoc = OriginalExpr->getBeginLoc();
2334  SourceLocation EndLoc = OriginalExpr->getEndLoc();
2335  if (BeginLoc.isMacroID() && EndLoc.isMacroID()) {
2336  const SourceManager &SM = BRC.getSourceManager();
2337  const LangOptions &LO = BRC.getASTContext().getLangOpts();
2338  if (Lexer::isAtStartOfMacroExpansion(BeginLoc, SM, LO) &&
2339  Lexer::isAtEndOfMacroExpansion(EndLoc, SM, LO)) {
2340  CharSourceRange R = Lexer::getAsCharRange({BeginLoc, EndLoc}, SM, LO);
2341  Out << Lexer::getSourceText(R, SM, LO);
2342  return false;
2343  }
2344  }
2345  }
2346 
2347  if (const auto *DR = dyn_cast<DeclRefExpr>(Ex)) {
2348  const bool quotes = isa<VarDecl>(DR->getDecl());
2349  if (quotes) {
2350  Out << '\'';
2351  const LocationContext *LCtx = N->getLocationContext();
2352  const ProgramState *state = N->getState().get();
2353  if (const MemRegion *R = state->getLValue(cast<VarDecl>(DR->getDecl()),
2354  LCtx).getAsRegion()) {
2355  if (report.isInteresting(R))
2356  prunable = false;
2357  else {
2358  const ProgramState *state = N->getState().get();
2359  SVal V = state->getSVal(R);
2360  if (report.isInteresting(V))
2361  prunable = false;
2362  }
2363  }
2364  }
2365  Out << DR->getDecl()->getDeclName().getAsString();
2366  if (quotes)
2367  Out << '\'';
2368  return quotes;
2369  }
2370 
2371  if (const auto *IL = dyn_cast<IntegerLiteral>(Ex)) {
2372  QualType OriginalTy = OriginalExpr->getType();
2373  if (OriginalTy->isPointerType()) {
2374  if (IL->getValue() == 0) {
2375  Out << "null";
2376  return false;
2377  }
2378  }
2379  else if (OriginalTy->isObjCObjectPointerType()) {
2380  if (IL->getValue() == 0) {
2381  Out << "nil";
2382  return false;
2383  }
2384  }
2385 
2386  Out << IL->getValue();
2387  return false;
2388  }
2389 
2390  if (const auto *ME = dyn_cast<MemberExpr>(Ex)) {
2391  if (!IsSameFieldName)
2392  Out << "field '" << ME->getMemberDecl()->getName() << '\'';
2393  else
2394  Out << '\''
2397  BRC.getSourceManager(), BRC.getASTContext().getLangOpts(), 0)
2398  << '\'';
2399  }
2400 
2401  return false;
2402 }
2403 
2404 PathDiagnosticPieceRef ConditionBRVisitor::VisitTrueTest(
2405  const Expr *Cond, const BinaryOperator *BExpr, BugReporterContext &BRC,
2406  PathSensitiveBugReport &R, const ExplodedNode *N, bool TookTrue,
2407  bool IsAssuming) {
2408  bool shouldInvert = false;
2409  Optional<bool> shouldPrune;
2410 
2411  // Check if the field name of the MemberExprs is ambiguous. Example:
2412  // " 'a.d' is equal to 'h.d' " in 'test/Analysis/null-deref-path-notes.cpp'.
2413  bool IsSameFieldName = false;
2414  const auto *LhsME = dyn_cast<MemberExpr>(BExpr->getLHS()->IgnoreParenCasts());
2415  const auto *RhsME = dyn_cast<MemberExpr>(BExpr->getRHS()->IgnoreParenCasts());
2416 
2417  if (LhsME && RhsME)
2418  IsSameFieldName =
2419  LhsME->getMemberDecl()->getName() == RhsME->getMemberDecl()->getName();
2420 
2421  SmallString<128> LhsString, RhsString;
2422  {
2423  llvm::raw_svector_ostream OutLHS(LhsString), OutRHS(RhsString);
2424  const bool isVarLHS = patternMatch(BExpr->getLHS(), BExpr, OutLHS, BRC, R,
2425  N, shouldPrune, IsSameFieldName);
2426  const bool isVarRHS = patternMatch(BExpr->getRHS(), BExpr, OutRHS, BRC, R,
2427  N, shouldPrune, IsSameFieldName);
2428 
2429  shouldInvert = !isVarLHS && isVarRHS;
2430  }
2431 
2432  BinaryOperator::Opcode Op = BExpr->getOpcode();
2433 
2435  // For assignment operators, all that we care about is that the LHS
2436  // evaluates to "true" or "false".
2437  return VisitConditionVariable(LhsString, BExpr->getLHS(), BRC, R, N,
2438  TookTrue);
2439  }
2440 
2441  // For non-assignment operations, we require that we can understand
2442  // both the LHS and RHS.
2443  if (LhsString.empty() || RhsString.empty() ||
2444  !BinaryOperator::isComparisonOp(Op) || Op == BO_Cmp)
2445  return nullptr;
2446 
2447  // Should we invert the strings if the LHS is not a variable name?
2448  SmallString<256> buf;
2449  llvm::raw_svector_ostream Out(buf);
2450  Out << (IsAssuming ? "Assuming " : "")
2451  << (shouldInvert ? RhsString : LhsString) << " is ";
2452 
2453  // Do we need to invert the opcode?
2454  if (shouldInvert)
2455  switch (Op) {
2456  default: break;
2457  case BO_LT: Op = BO_GT; break;
2458  case BO_GT: Op = BO_LT; break;
2459  case BO_LE: Op = BO_GE; break;
2460  case BO_GE: Op = BO_LE; break;
2461  }
2462 
2463  if (!TookTrue)
2464  switch (Op) {
2465  case BO_EQ: Op = BO_NE; break;
2466  case BO_NE: Op = BO_EQ; break;
2467  case BO_LT: Op = BO_GE; break;
2468  case BO_GT: Op = BO_LE; break;
2469  case BO_LE: Op = BO_GT; break;
2470  case BO_GE: Op = BO_LT; break;
2471  default:
2472  return nullptr;
2473  }
2474 
2475  switch (Op) {
2476  case BO_EQ:
2477  Out << "equal to ";
2478  break;
2479  case BO_NE:
2480  Out << "not equal to ";
2481  break;
2482  default:
2483  Out << BinaryOperator::getOpcodeStr(Op) << ' ';
2484  break;
2485  }
2486 
2487  Out << (shouldInvert ? LhsString : RhsString);
2488  const LocationContext *LCtx = N->getLocationContext();
2489  const SourceManager &SM = BRC.getSourceManager();
2490 
2491  if (isVarAnInterestingCondition(BExpr->getLHS(), N, &R) ||
2492  isVarAnInterestingCondition(BExpr->getRHS(), N, &R))
2493  Out << WillBeUsedForACondition;
2494 
2495  // Convert 'field ...' to 'Field ...' if it is a MemberExpr.
2496  std::string Message = Out.str();
2497  Message[0] = toupper(Message[0]);
2498 
2499  // If we know the value create a pop-up note to the value part of 'BExpr'.
2500  if (!IsAssuming) {
2501  PathDiagnosticLocation Loc;
2502  if (!shouldInvert) {
2503  if (LhsME && LhsME->getMemberLoc().isValid())
2504  Loc = PathDiagnosticLocation(LhsME->getMemberLoc(), SM);
2505  else
2506  Loc = PathDiagnosticLocation(BExpr->getLHS(), SM, LCtx);
2507  } else {
2508  if (RhsME && RhsME->getMemberLoc().isValid())
2509  Loc = PathDiagnosticLocation(RhsME->getMemberLoc(), SM);
2510  else
2511  Loc = PathDiagnosticLocation(BExpr->getRHS(), SM, LCtx);
2512  }
2513 
2514  return std::make_shared<PathDiagnosticPopUpPiece>(Loc, Message);
2515  }
2516 
2517  PathDiagnosticLocation Loc(Cond, SM, LCtx);
2518  auto event = std::make_shared<PathDiagnosticEventPiece>(Loc, Message);
2519  if (shouldPrune.hasValue())
2520  event->setPrunable(shouldPrune.getValue());
2521  return event;
2522 }
2523 
2524 PathDiagnosticPieceRef ConditionBRVisitor::VisitConditionVariable(
2525  StringRef LhsString, const Expr *CondVarExpr, BugReporterContext &BRC,
2526  PathSensitiveBugReport &report, const ExplodedNode *N, bool TookTrue) {
2527  // FIXME: If there's already a constraint tracker for this variable,
2528  // we shouldn't emit anything here (c.f. the double note in
2529  // test/Analysis/inlining/path-notes.c)
2530  SmallString<256> buf;
2531  llvm::raw_svector_ostream Out(buf);
2532  Out << "Assuming " << LhsString << " is ";
2533 
2534  if (!printValue(CondVarExpr, Out, N, TookTrue, /*IsAssuming=*/true))
2535  return nullptr;
2536 
2537  const LocationContext *LCtx = N->getLocationContext();
2538  PathDiagnosticLocation Loc(CondVarExpr, BRC.getSourceManager(), LCtx);
2539 
2540  if (isVarAnInterestingCondition(CondVarExpr, N, &report))
2541  Out << WillBeUsedForACondition;
2542 
2543  auto event = std::make_shared<PathDiagnosticEventPiece>(Loc, Out.str());
2544 
2545  if (isInterestingExpr(CondVarExpr, N, &report))
2546  event->setPrunable(false);
2547 
2548  return event;
2549 }
2550 
2551 PathDiagnosticPieceRef ConditionBRVisitor::VisitTrueTest(
2552  const Expr *Cond, const DeclRefExpr *DRE, BugReporterContext &BRC,
2553  PathSensitiveBugReport &report, const ExplodedNode *N, bool TookTrue,
2554  bool IsAssuming) {
2555  const auto *VD = dyn_cast<VarDecl>(DRE->getDecl());
2556  if (!VD)
2557  return nullptr;
2558 
2559  SmallString<256> Buf;
2560  llvm::raw_svector_ostream Out(Buf);
2561 
2562  Out << (IsAssuming ? "Assuming '" : "'") << VD->getDeclName() << "' is ";
2563 
2564  if (!printValue(DRE, Out, N, TookTrue, IsAssuming))
2565  return nullptr;
2566 
2567  const LocationContext *LCtx = N->getLocationContext();
2568 
2569  if (isVarAnInterestingCondition(DRE, N, &report))
2570  Out << WillBeUsedForACondition;
2571 
2572  // If we know the value create a pop-up note to the 'DRE'.
2573  if (!IsAssuming) {
2574  PathDiagnosticLocation Loc(DRE, BRC.getSourceManager(), LCtx);
2575  return std::make_shared<PathDiagnosticPopUpPiece>(Loc, Out.str());
2576  }
2577 
2578  PathDiagnosticLocation Loc(Cond, BRC.getSourceManager(), LCtx);
2579  auto event = std::make_shared<PathDiagnosticEventPiece>(Loc, Out.str());
2580 
2581  if (isInterestingExpr(DRE, N, &report))
2582  event->setPrunable(false);
2583 
2584  return std::move(event);
2585 }
2586 
2587 PathDiagnosticPieceRef ConditionBRVisitor::VisitTrueTest(
2588  const Expr *Cond, const MemberExpr *ME, BugReporterContext &BRC,
2589  PathSensitiveBugReport &report, const ExplodedNode *N, bool TookTrue,
2590  bool IsAssuming) {
2591  SmallString<256> Buf;
2592  llvm::raw_svector_ostream Out(Buf);
2593 
2594  Out << (IsAssuming ? "Assuming field '" : "Field '")
2595  << ME->getMemberDecl()->getName() << "' is ";
2596 
2597  if (!printValue(ME, Out, N, TookTrue, IsAssuming))
2598  return nullptr;
2599 
2600  const LocationContext *LCtx = N->getLocationContext();
2601  PathDiagnosticLocation Loc;
2602 
2603  // If we know the value create a pop-up note to the member of the MemberExpr.
2604  if (!IsAssuming && ME->getMemberLoc().isValid())
2605  Loc = PathDiagnosticLocation(ME->getMemberLoc(), BRC.getSourceManager());
2606  else
2607  Loc = PathDiagnosticLocation(Cond, BRC.getSourceManager(), LCtx);
2608 
2609  if (!Loc.isValid() || !Loc.asLocation().isValid())
2610  return nullptr;
2611 
2612  if (isVarAnInterestingCondition(ME, N, &report))
2613  Out << WillBeUsedForACondition;
2614 
2615  // If we know the value create a pop-up note.
2616  if (!IsAssuming)
2617  return std::make_shared<PathDiagnosticPopUpPiece>(Loc, Out.str());
2618 
2619  auto event = std::make_shared<PathDiagnosticEventPiece>(Loc, Out.str());
2620  if (isInterestingExpr(ME, N, &report))
2621  event->setPrunable(false);
2622  return event;
2623 }
2624 
2625 bool ConditionBRVisitor::printValue(const Expr *CondVarExpr, raw_ostream &Out,
2626  const ExplodedNode *N, bool TookTrue,
2627  bool IsAssuming) {
2628  QualType Ty = CondVarExpr->getType();
2629 
2630  if (Ty->isPointerType()) {
2631  Out << (TookTrue ? "non-null" : "null");
2632  return true;
2633  }
2634 
2635  if (Ty->isObjCObjectPointerType()) {
2636  Out << (TookTrue ? "non-nil" : "nil");
2637  return true;
2638  }
2639 
2640  if (!Ty->isIntegralOrEnumerationType())
2641  return false;
2642 
2644  if (!IsAssuming)
2645  IntValue = getConcreteIntegerValue(CondVarExpr, N);
2646 
2647  if (IsAssuming || !IntValue.hasValue()) {
2648  if (Ty->isBooleanType())
2649  Out << (TookTrue ? "true" : "false");
2650  else
2651  Out << (TookTrue ? "not equal to 0" : "0");
2652  } else {
2653  if (Ty->isBooleanType())
2654  Out << (IntValue.getValue()->getBoolValue() ? "true" : "false");
2655  else
2656  Out << *IntValue.getValue();
2657  }
2658 
2659  return true;
2660 }
2661 
2662 constexpr llvm::StringLiteral ConditionBRVisitor::GenericTrueMessage;
2663 constexpr llvm::StringLiteral ConditionBRVisitor::GenericFalseMessage;
2664 
2665 bool ConditionBRVisitor::isPieceMessageGeneric(
2666  const PathDiagnosticPiece *Piece) {
2667  return Piece->getString() == GenericTrueMessage ||
2668  Piece->getString() == GenericFalseMessage;
2669 }
2670 
2671 //===----------------------------------------------------------------------===//
2672 // Implementation of LikelyFalsePositiveSuppressionBRVisitor.
2673 //===----------------------------------------------------------------------===//
2674 
2675 void LikelyFalsePositiveSuppressionBRVisitor::finalizeVisitor(
2676  BugReporterContext &BRC, const ExplodedNode *N,
2677  PathSensitiveBugReport &BR) {
2678  // Here we suppress false positives coming from system headers. This list is
2679  // based on known issues.
2680  const AnalyzerOptions &Options = BRC.getAnalyzerOptions();
2681  const Decl *D = N->getLocationContext()->getDecl();
2682 
2684  // Skip reports within the 'std' namespace. Although these can sometimes be
2685  // the user's fault, we currently don't report them very well, and
2686  // Note that this will not help for any other data structure libraries, like
2687  // TR1, Boost, or llvm/ADT.
2688  if (Options.ShouldSuppressFromCXXStandardLibrary) {
2689  BR.markInvalid(getTag(), nullptr);
2690  return;
2691  } else {
2692  // If the complete 'std' suppression is not enabled, suppress reports
2693  // from the 'std' namespace that are known to produce false positives.
2694 
2695  // The analyzer issues a false use-after-free when std::list::pop_front
2696  // or std::list::pop_back are called multiple times because we cannot
2697  // reason about the internal invariants of the data structure.
2698  if (const auto *MD = dyn_cast<CXXMethodDecl>(D)) {
2699  const CXXRecordDecl *CD = MD->getParent();
2700  if (CD->getName() == "list") {
2701  BR.markInvalid(getTag(), nullptr);
2702  return;
2703  }
2704  }
2705 
2706  // The analyzer issues a false positive when the constructor of
2707  // std::__independent_bits_engine from algorithms is used.
2708  if (const auto *MD = dyn_cast<CXXConstructorDecl>(D)) {
2709  const CXXRecordDecl *CD = MD->getParent();
2710  if (CD->getName() == "__independent_bits_engine") {
2711  BR.markInvalid(getTag(), nullptr);
2712  return;
2713  }
2714  }
2715 
2716  for (const LocationContext *LCtx = N->getLocationContext(); LCtx;
2717  LCtx = LCtx->getParent()) {
2718  const auto *MD = dyn_cast<CXXMethodDecl>(LCtx->getDecl());
2719  if (!MD)
2720  continue;
2721 
2722  const CXXRecordDecl *CD = MD->getParent();
2723  // The analyzer issues a false positive on
2724  // std::basic_string<uint8_t> v; v.push_back(1);
2725  // and
2726  // std::u16string s; s += u'a';
2727  // because we cannot reason about the internal invariants of the
2728  // data structure.
2729  if (CD->getName() == "basic_string") {
2730  BR.markInvalid(getTag(), nullptr);
2731  return;
2732  }
2733 
2734  // The analyzer issues a false positive on
2735  // std::shared_ptr<int> p(new int(1)); p = nullptr;
2736  // because it does not reason properly about temporary destructors.
2737  if (CD->getName() == "shared_ptr") {
2738  BR.markInvalid(getTag(), nullptr);
2739  return;
2740  }
2741  }
2742  }
2743  }
2744 
2745  // Skip reports within the sys/queue.h macros as we do not have the ability to
2746  // reason about data structure shapes.
2747  const SourceManager &SM = BRC.getSourceManager();
2748  FullSourceLoc Loc = BR.getLocation().asLocation();
2749  while (Loc.isMacroID()) {
2750  Loc = Loc.getSpellingLoc();
2751  if (SM.getFilename(Loc).endswith("sys/queue.h")) {
2752  BR.markInvalid(getTag(), nullptr);
2753  return;
2754  }
2755  }
2756 }
2757 
2758 //===----------------------------------------------------------------------===//
2759 // Implementation of UndefOrNullArgVisitor.
2760 //===----------------------------------------------------------------------===//
2761 
2763 UndefOrNullArgVisitor::VisitNode(const ExplodedNode *N, BugReporterContext &BRC,
2764  PathSensitiveBugReport &BR) {
2765  ProgramStateRef State = N->getState();
2766  ProgramPoint ProgLoc = N->getLocation();
2767 
2768  // We are only interested in visiting CallEnter nodes.
2769  Optional<CallEnter> CEnter = ProgLoc.getAs<CallEnter>();
2770  if (!CEnter)
2771  return nullptr;
2772 
2773  // Check if one of the arguments is the region the visitor is tracking.
2774  CallEventManager &CEMgr = BRC.getStateManager().getCallEventManager();
2775  CallEventRef<> Call = CEMgr.getCaller(CEnter->getCalleeContext(), State);
2776  unsigned Idx = 0;
2777  ArrayRef<ParmVarDecl *> parms = Call->parameters();
2778 
2779  for (const auto ParamDecl : parms) {
2780  const MemRegion *ArgReg = Call->getArgSVal(Idx).getAsRegion();
2781  ++Idx;
2782 
2783  // Are we tracking the argument or its subregion?
2784  if ( !ArgReg || !R->isSubRegionOf(ArgReg->StripCasts()))
2785  continue;
2786 
2787  // Check the function parameter type.
2788  assert(ParamDecl && "Formal parameter has no decl?");
2789  QualType T = ParamDecl->getType();
2790 
2791  if (!(T->isAnyPointerType() || T->isReferenceType())) {
2792  // Function can only change the value passed in by address.
2793  continue;
2794  }
2795 
2796  // If it is a const pointer value, the function does not intend to
2797  // change the value.
2798  if (T->getPointeeType().isConstQualified())
2799  continue;
2800 
2801  // Mark the call site (LocationContext) as interesting if the value of the
2802  // argument is undefined or '0'/'NULL'.
2803  SVal BoundVal = State->getSVal(R);
2804  if (BoundVal.isUndef() || BoundVal.isZeroConstant()) {
2805  BR.markInteresting(CEnter->getCalleeContext());
2806  return nullptr;
2807  }
2808  }
2809  return nullptr;
2810 }
2811 
2812 //===----------------------------------------------------------------------===//
2813 // Implementation of FalsePositiveRefutationBRVisitor.
2814 //===----------------------------------------------------------------------===//
2815 
2816 FalsePositiveRefutationBRVisitor::FalsePositiveRefutationBRVisitor()
2817  : Constraints(ConstraintRangeTy::Factory().getEmptyMap()) {}
2818 
2819 void FalsePositiveRefutationBRVisitor::finalizeVisitor(
2820  BugReporterContext &BRC, const ExplodedNode *EndPathNode,
2821  PathSensitiveBugReport &BR) {
2822  // Collect new constraints
2823  VisitNode(EndPathNode, BRC, BR);
2824 
2825  // Create a refutation manager
2826  llvm::SMTSolverRef RefutationSolver = llvm::CreateZ3Solver();
2827  ASTContext &Ctx = BRC.getASTContext();
2828 
2829  // Add constraints to the solver
2830  for (const auto &I : Constraints) {
2831  const SymbolRef Sym = I.first;
2832  auto RangeIt = I.second.begin();
2833 
2834  llvm::SMTExprRef Constraints = SMTConv::getRangeExpr(
2835  RefutationSolver, Ctx, Sym, RangeIt->From(), RangeIt->To(),
2836  /*InRange=*/true);
2837  while ((++RangeIt) != I.second.end()) {
2838  Constraints = RefutationSolver->mkOr(
2839  Constraints, SMTConv::getRangeExpr(RefutationSolver, Ctx, Sym,
2840  RangeIt->From(), RangeIt->To(),
2841  /*InRange=*/true));
2842  }
2843 
2844  RefutationSolver->addConstraint(Constraints);
2845  }
2846 
2847  // And check for satisfiability
2848  Optional<bool> isSat = RefutationSolver->check();
2849  if (!isSat.hasValue())
2850  return;
2851 
2852  if (!isSat.getValue())
2853  BR.markInvalid("Infeasible constraints", EndPathNode->getLocationContext());
2854 }
2855 
2856 PathDiagnosticPieceRef FalsePositiveRefutationBRVisitor::VisitNode(
2857  const ExplodedNode *N, BugReporterContext &, PathSensitiveBugReport &) {
2858  // Collect new constraints
2859  const ConstraintRangeTy &NewCs = N->getState()->get<ConstraintRange>();
2860  ConstraintRangeTy::Factory &CF =
2861  N->getState()->get_context<ConstraintRange>();
2862 
2863  // Add constraints if we don't have them yet
2864  for (auto const &C : NewCs) {
2865  const SymbolRef &Sym = C.first;
2866  if (!Constraints.contains(Sym)) {
2867  Constraints = CF.add(Constraints, Sym, C.second);
2868  }
2869  }
2870 
2871  return nullptr;
2872 }
2873 
2874 void FalsePositiveRefutationBRVisitor::Profile(
2875  llvm::FoldingSetNodeID &ID) const {
2876  static int Tag = 0;
2877  ID.AddPointer(&Tag);
2878 }
2879 
2880 //===----------------------------------------------------------------------===//
2881 // Implementation of TagVisitor.
2882 //===----------------------------------------------------------------------===//
2883 
2884 int NoteTag::Kind = 0;
2885 
2886 void TagVisitor::Profile(llvm::FoldingSetNodeID &ID) const {
2887  static int Tag = 0;
2888  ID.AddPointer(&Tag);
2889 }
2890 
2891 PathDiagnosticPieceRef TagVisitor::VisitNode(const ExplodedNode *N,
2892  BugReporterContext &BRC,
2893  PathSensitiveBugReport &R) {
2894  ProgramPoint PP = N->getLocation();
2895  const NoteTag *T = dyn_cast_or_null<NoteTag>(PP.getTag());
2896  if (!T)
2897  return nullptr;
2898 
2899  if (Optional<std::string> Msg = T->generateMessage(BRC, R)) {
2900  PathDiagnosticLocation Loc =
2901  PathDiagnosticLocation::create(PP, BRC.getSourceManager());
2902  auto Piece = std::make_shared<PathDiagnosticEventPiece>(Loc, *Msg);
2903  Piece->setPrunable(T->isPrunable());
2904  return Piece;
2905  }
2906 
2907  return nullptr;
2908 }
ObjCPropertyRefExpr - A dot-syntax expression to access an ObjC property.
Definition: ExprObjC.h:614
Indicates that the tracked object is a CF object.
Defines the clang::ASTContext interface.
static ArrayRef< ParmVarDecl * > getCallParameters(CallEventRef<> Call)
Get parameters associated with runtime definition in order to get the correct parameter name...
This is a discriminated union of FileInfo and ExpansionInfo.
A (possibly-)qualified type.
Definition: Type.h:643
static bool isPointerToConst(QualType Ty)
ValueDecl * getMemberDecl() const
Retrieve the member declaration to which this expression refers.
Definition: Expr.h:2894
static StringRef getMacroName(SourceLocation Loc, BugReporterContext &BRC)
const internal::VariadicAllOfMatcher< Stmt > stmt
Matches statements.
succ_iterator succ_begin()
Definition: CFG.h:956
virtual Stmt * getBody() const
getBody - If this Decl represents a declaration for a body of code, such as a function or method defi...
Definition: DeclBase.h:986
static llvm::StringLiteral WillBeUsedForACondition
Stmt - This represents one statement.
Definition: Stmt.h:66
internal::Matcher< Stmt > StatementMatcher
Definition: ASTMatchers.h:138
QualType getPointeeType() const
If this is a pointer, ObjC object pointer, or block pointer, this returns the respective pointee...
Definition: Type.cpp:557
internal::PolymorphicMatcherWithParam1< internal::HasDeclarationMatcher, internal::Matcher< Decl >, void(internal::HasDeclarationSupportedTypes)> hasDeclaration(const internal::Matcher< Decl > &InnerMatcher)
Matches a node if the declaration associated with that node matches the given matcher.
Definition: ASTMatchers.h:2971
C Language Family Type Representation.
Defines the SourceManager interface.
static CharSourceRange getTokenRange(SourceRange R)
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:88
Represents a point when we begin processing an inlined call.
Definition: ProgramPoint.h:630
Manages the lifetime of CallEvent objects.
Definition: CallEvent.h:1148
IntrusiveRefCntPtr< const ProgramState > ProgramStateRef
Opcode getOpcode() const
Definition: Expr.h:3444
StringRef P
const internal::ArgumentAdaptingMatcherFunc< internal::HasDescendantMatcher > hasDescendant
Matches AST nodes that have descendant AST nodes that match the provided matcher. ...
Each ExpansionInfo encodes the expansion location - where the token was ultimately expanded...
llvm::ImmutableMap< SymbolRef, RangeSet > ConstraintRangeTy
unsigned succ_size() const
Definition: CFG.h:974
static bool isAtStartOfMacroExpansion(SourceLocation loc, const SourceManager &SM, const LangOptions &LangOpts, SourceLocation *MacroBegin=nullptr)
Returns true if the given MacroID location points at the first token of the macro expansion...
Definition: Lexer.cpp:800
Represents a variable declaration or definition.
Definition: Decl.h:827
const internal::VariadicDynCastAllOfMatcher< Stmt, BinaryOperator > binaryOperator
Matches binary operator expressions.
const internal::VariadicDynCastAllOfMatcher< Stmt, ObjCIvarRefExpr > objcIvarRefExpr
Matches a reference to an ObjCIvar.
Describes how types, statements, expressions, and declarations should be printed. ...
Definition: PrettyPrinter.h:37
Represents a parameter to a function.
Definition: Decl.h:1600
Defines the clang::Expr interface and subclasses for C++ expressions.
bool isParentOf(const LocationContext *LC) const
Represents a struct/union/class.
Definition: Decl.h:3662
const SymExpr * SymbolRef
Definition: SymExpr.h:110
SourceLocation getBegin() const
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:160
LineState State
field_range fields() const
Definition: Decl.h:3877
SourceLocation getBeginLoc() const LLVM_READONLY
Definition: Stmt.cpp:274
Represents a member of a struct/union/class.
Definition: Decl.h:2643
Represents a program point after a store evaluation.
Definition: ProgramPoint.h:431
bool isReferenceType() const
Definition: Type.h:6403
Keeps track of the various options that can be enabled, which controls the dialect of C or C++ that i...
Definition: LangOptions.h:49
i32 captured_struct **param SharedsTy A type which contains references the shared variables *param Shareds Context with the list of shared variables from the p *TaskFunction *param Data Additional data for task generation like final * state
bool isAssignmentOp() const
Definition: Expr.h:3538
bool isIntegralOrEnumerationType() const
Determine whether this type is an integral or enumeration type.
Definition: Type.h:6754
Represents a point when we start the call exit sequence (for inlined call).
Definition: ProgramPoint.h:668
std::shared_ptr< PathDiagnosticPiece > PathDiagnosticPieceRef
StringRef getOpcodeStr() const
Definition: Expr.h:3465
bool isGLValue() const
Definition: Expr.h:261
BinaryOperatorKind
static bool isInStdNamespace(const Decl *D)
Returns true if the root namespace of the given declaration is the &#39;std&#39; C++ namespace.
Forward-declares and imports various common LLVM datatypes that clang wants to use unqualified...
const LocationContext * getParent() const
A builtin binary operation expression such as "x + y" or "x <= y".
Definition: Expr.h:3409
static bool wasRegionOfInterestModifiedAt(const SubRegion *RegionOfInterest, const ExplodedNode *N, SVal ValueAfter)
Expr * IgnoreParenCasts() LLVM_READONLY
Skip past any parentheses and casts which might surround this expression until reaching a fixed point...
Definition: Expr.cpp:2971
static const Expr * peelOffPointerArithmetic(const BinaryOperator *B)
static PathDiagnosticLocation create(const Decl *D, const SourceManager &SM)
Create a location corresponding to the given declaration.
static const MemRegion * getLocationRegionIfReference(const Expr *E, const ExplodedNode *N)
static Optional< const llvm::APSInt * > getConcreteIntegerValue(const Expr *CondVarExpr, const ExplodedNode *N)
SmallVector< BoundNodes, 1 > match(MatcherT Matcher, const NodeT &Node, ASTContext &Context)
Returns the results of matching Matcher on Node.
static bool hasVisibleUpdate(const ExplodedNode *LeftNode, SVal LeftVal, const ExplodedNode *RightNode, SVal RightVal)
Comparing internal representations of symbolic values (via SVal::operator==()) is a valid way to chec...
Expr * IgnoreImpCasts() LLVM_READONLY
Skip past any implicit casts which might surround this expression until reaching a fixed point...
Definition: Expr.cpp:2950
NodeId Parent
Definition: ASTDiff.cpp:191
RecordDecl * getAsRecordDecl() const
Retrieves the RecordDecl this type refers to.
Definition: Type.cpp:1696
static bool isAssertlikeBlock(const CFGBlock *B, ASTContext &Context)
const Stmt * getCallSite() const
Represents a single basic block in a source-level CFG.
Definition: CFG.h:576
static bool potentiallyWritesIntoIvar(const Decl *Parent, const ObjCIvarDecl *Ivar)
Represents a point when we finish the call exit sequence (for inlined call).
Definition: ProgramPoint.h:688
static StringRef getSourceText(CharSourceRange Range, const SourceManager &SM, const LangOptions &LangOpts, bool *Invalid=nullptr)
Returns a string for the source that the range encompasses.
Definition: Lexer.cpp:939
static bool isAtEndOfMacroExpansion(SourceLocation loc, const SourceManager &SM, const LangOptions &LangOpts, SourceLocation *MacroEnd=nullptr)
Returns true if the given MacroID location points at the last token of the macro expansion.
Definition: Lexer.cpp:822
This represents one expression.
Definition: Expr.h:108
Stmt * getTerminatorCondition(bool StripParens=true)
Definition: CFG.cpp:5895
static Optional< SVal > getSValForVar(const Expr *CondVarExpr, const ExplodedNode *N)
Represents a character-granular source range.
CFGBlock * getBlock(Stmt *S)
Returns the CFGBlock the specified Stmt* appears in.
Definition: CFGStmtMap.cpp:26
const Expr * getLastCondition() const
Definition: CFG.cpp:5871
CallEventRef getCaller(const StackFrameContext *CalleeCtx, ProgramStateRef State)
Gets an outside caller given a callee context.
Definition: CallEvent.cpp:1380
#define V(N, I)
Definition: ASTContext.h:2921
bool inTopFrame() const override
Return true if the current LocationContext has no caller context.
Defines the clang::IdentifierInfo, clang::IdentifierTable, and clang::Selector interfaces.
static std::pair< const ProgramPointTag *, const ProgramPointTag * > geteagerlyAssumeBinOpBifurcationTags()
QualType getType() const
Definition: Expr.h:137
CharSourceRange getImmediateExpansionRange(SourceLocation Loc) const
Return the start/end of the expansion information for an expansion location.
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:2620
An expression that sends a message to the given Objective-C object or class.
Definition: ExprObjC.h:950
SourceLocation getMemberLoc() const
getMemberLoc - Return the location of the "member", in X->F, it is the location of &#39;F&#39;...
Definition: Expr.h:3000
ValueDecl * getDecl()
Definition: Expr.h:1222
bool isNull() const
Return true if this QualType doesn&#39;t point to a type yet.
Definition: Type.h:708
const SourceManager & SM
Definition: Format.cpp:1667
const ExpansionInfo & getExpansion() const
SourceLocation getEndLoc() const LLVM_READONLY
Definition: Stmt.cpp:287
virtual bool hasBody() const
Returns true if this Decl represents a declaration for a body of code, such as a function or method d...
Definition: DeclBase.h:992
bool isConstQualified() const
Determine whether this type is const-qualified.
Definition: Type.h:6207
bool isComparisonOp() const
Definition: Expr.h:3500
Maps string IDs to AST nodes matched by parts of a matcher.
Definition: ASTMatchers.h:103
StringRef getFilename(SourceLocation SpellingLoc) const
Return the filename of the file containing a SourceLocation.
static PathDiagnosticLocation createBegin(const Decl *D, const SourceManager &SM)
Create a location for the beginning of the declaration.
QualType getCanonicalType() const
Definition: Type.h:6187
Encodes a location in the source.
static std::shared_ptr< PathDiagnosticEventPiece > constructDebugPieceForTrackedCondition(const Expr *Cond, const ExplodedNode *N, BugReporterContext &BRC)
static bool isCallStmt(const Stmt *S)
Returns true if this is a statement is a function or method call of some kind.
Definition: CallEvent.cpp:456
static bool Ret(InterpState &S, CodePtr &PC, APValue &Result)
Definition: Interp.cpp:34
ProgramPoints can be "tagged" as representing points specific to a given analysis entity...
Definition: ProgramPoint.h:39
std::string getNameAsString() const
Get a human-readable name for the declaration, even if it is one of the special kinds of names (C++ c...
Definition: Decl.h:291
ASTContext & getASTContext() const LLVM_READONLY
Definition: DeclBase.cpp:377
DeclStmt - Adaptor class for mixing declarations with statements and expressions. ...
Definition: Stmt.h:1213
Represents a static or instance method of a struct/union/class.
Definition: DeclCXX.h:1905
bool isAnyPointerType() const
Definition: Type.h:6395
bool isObjCObjectPointerType() const
Definition: Type.h:6495
static void showBRDiagnostics(const char *action, llvm::raw_svector_ostream &os, const MemRegion *R, SVal V, const DeclStmt *DS)
Show diagnostics for initializing or declaring a region R with a bad value.
static StringRef getImmediateMacroName(SourceLocation Loc, const SourceManager &SM, const LangOptions &LangOpts)
Retrieve the name of the immediate macro expansion.
Definition: Lexer.cpp:975
static bool isFunctionMacroExpansion(SourceLocation Loc, const SourceManager &SM)
Expr * getLHS() const
Definition: Expr.h:3449
ast_type_traits::DynTypedNode Node
bool isInevitablySinking() const
Returns true if the block would eventually end with a sink (a noreturn node).
Definition: CFG.cpp:5833
Dataflow Directional Tag Classes.
static void showBRDefaultDiagnostics(llvm::raw_svector_ostream &os, const MemRegion *R, SVal V)
Show default diagnostics for storing bad region.
bool isValid() const
Return true if this is a valid SourceLocation object.
Parameter for Objective-C &#39;self&#39; argument.
Definition: Decl.h:1545
static bool isVarAnInterestingCondition(const Expr *CondVarExpr, const ExplodedNode *N, const PathSensitiveBugReport *B)
StmtClass getStmtClass() const
Definition: Stmt.h:1097
bool isBooleanType() const
Definition: Type.h:6767
const Decl * getSingleDecl() const
Definition: Stmt.h:1228
const ProgramPointTag * getTag() const
Definition: ProgramPoint.h:177
Stmt * getTerminatorStmt()
Definition: CFG.h:1051
static void showBRParamDiagnostics(llvm::raw_svector_ostream &os, const VarRegion *VR, SVal V)
Display diagnostics for passing bad region as a parameter.
bool isMacroID() const
static bool isInterestingExpr(const Expr *E, const ExplodedNode *N, const PathSensitiveBugReport *B)
static CharSourceRange getAsCharRange(SourceRange Range, const SourceManager &SM, const LangOptions &LangOpts)
Given a token range, produce a corresponding CharSourceRange that is not a token range.
Definition: Lexer.h:394
bool isMacroArgExpansion(SourceLocation Loc, SourceLocation *StartLoc=nullptr) const
Tests whether the given source location represents a macro argument&#39;s expansion into the function-lik...
Indicates that the tracking object is a descendant of a referenced-counted OSObject, used in the Darwin kernel.
const LocationContext * getLocationContext() const
Definition: ProgramPoint.h:179
static bool isAdditiveOp(Opcode Opc)
Definition: Expr.h:3485
const StackFrameContext * getStackFrame() const
Stores options for the analyzer from the command line.
const SrcMgr::SLocEntry & getSLocEntry(FileID FID, bool *Invalid=nullptr) const
ObjCIvarRefExpr - A reference to an ObjC instance variable.
Definition: ExprObjC.h:546
X
Add a minimal nested name specifier fixit hint to allow lookup of a tag name from an outer enclosing ...
Definition: SemaDecl.cpp:14652
Defines the C++ Decl subclasses, other than those for templates (found in DeclTemplate.h) and friends (in DeclFriend.h).
MemberExpr - [C99 6.5.2.3] Structure and Union Members.
Definition: Expr.h:2811
Defines the clang::SourceLocation class and associated facilities.
Represents a C++ struct/union/class.
Definition: DeclCXX.h:255
bool isVoidType() const
Definition: Type.h:6650
ObjCIvarDecl - Represents an ObjC instance variable.
Definition: DeclObjC.h:1944
static bool isInitializationOfVar(const ExplodedNode *N, const VarRegion *VR)
Returns true if N represents the DeclStmt declaring and initializing VR.
SourceRange getSourceRange() const LLVM_READONLY
SourceLocation tokens are not useful in isolation - they are low level value objects created/interpre...
Definition: Stmt.cpp:262
FullSourceLoc getSpellingLoc() const
A SourceLocation and its associated SourceManager.
StringRef getName() const
Get the name of identifier for this declaration as a StringRef.
Definition: Decl.h:275
A reference to a declared variable, function, enum, etc.
Definition: Expr.h:1146
Expr * getRHS() const
Definition: Expr.h:3451
bool isFunctionMacroExpansion() const
bool isPointerType() const
Definition: Type.h:6391
QualType getType() const
Definition: Decl.h:655
A trivial tuple used to represent a source range.
Optional< T > getAs() const
Convert to the specified ProgramPoint type, returning None if this ProgramPoint is not of the desired...
Definition: ProgramPoint.h:151
static bool isInterestingLValueExpr(const Expr *Ex)
Returns true if nodes for the given expression kind are always kept around.
This class handles loading and caching of source files into memory.
std::pair< FileID, unsigned > getDecomposedLoc(SourceLocation Loc) const
Decompose the specified location into a raw FileID + Offset pair.
Expr * IgnoreParens() LLVM_READONLY
Skip past any parentheses which might surround this expression until reaching a fixed point...
Definition: Expr.cpp:2962
static llvm::SMTExprRef getRangeExpr(llvm::SMTSolverRef &Solver, ASTContext &Ctx, SymbolRef Sym, const llvm::APSInt &From, const llvm::APSInt &To, bool InRange)
Definition: SMTConv.h:504