BugReporter.cpp revision 2110350909701fcd6b55c636e24a675f0a905fea 
1// BugReporter.cpp - Generate PathDiagnostics for Bugs ------------*- C++ -*--//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10//  This file defines BugReporter, a utility class for generating
11//  PathDiagnostics.
12//
13//===----------------------------------------------------------------------===//
14
15#define DEBUG_TYPE "BugReporter"
16
17#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
18#include "clang/AST/ASTContext.h"
19#include "clang/AST/DeclObjC.h"
20#include "clang/AST/Expr.h"
21#include "clang/AST/ParentMap.h"
22#include "clang/AST/StmtObjC.h"
23#include "clang/Analysis/CFG.h"
24#include "clang/Analysis/ProgramPoint.h"
25#include "clang/Basic/SourceManager.h"
26#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
27#include "clang/StaticAnalyzer/Core/BugReporter/PathDiagnostic.h"
28#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
29#include "llvm/ADT/DenseMap.h"
30#include "llvm/ADT/IntrusiveRefCntPtr.h"
31#include "llvm/ADT/OwningPtr.h"
32#include "llvm/ADT/STLExtras.h"
33#include "llvm/ADT/SmallString.h"
34#include "llvm/ADT/Statistic.h"
35#include "llvm/Support/raw_ostream.h"
36#include <queue>
37
38using namespace clang;
39using namespace ento;
40
41STATISTIC(MaxBugClassSize,
42          "The maximum number of bug reports in the same equivalence class");
43STATISTIC(MaxValidBugClassSize,
44          "The maximum number of bug reports in the same equivalence class "
45          "where at least one report is valid (not suppressed)");
46
47BugReporterVisitor::~BugReporterVisitor() {}
48
49void BugReporterContext::anchor() {}
50
51//===----------------------------------------------------------------------===//
52// Helper routines for walking the ExplodedGraph and fetching statements.
53//===----------------------------------------------------------------------===//
54
55static inline const Stmt *GetStmt(const ProgramPoint &P) {
56  if (Optional<StmtPoint> SP = P.getAs<StmtPoint>())
57    return SP->getStmt();
58  if (Optional<BlockEdge> BE = P.getAs<BlockEdge>())
59    return BE->getSrc()->getTerminator();
60  if (Optional<CallEnter> CE = P.getAs<CallEnter>())
61    return CE->getCallExpr();
62  if (Optional<CallExitEnd> CEE = P.getAs<CallExitEnd>())
63    return CEE->getCalleeContext()->getCallSite();
64
65  return 0;
66}
67
68static inline const ExplodedNode*
69GetPredecessorNode(const ExplodedNode *N) {
70  return N->pred_empty() ? NULL : *(N->pred_begin());
71}
72
73static inline const ExplodedNode*
74GetSuccessorNode(const ExplodedNode *N) {
75  return N->succ_empty() ? NULL : *(N->succ_begin());
76}
77
78static const Stmt *GetPreviousStmt(const ExplodedNode *N) {
79  for (N = GetPredecessorNode(N); N; N = GetPredecessorNode(N))
80    if (const Stmt *S = GetStmt(N->getLocation()))
81      return S;
82
83  return 0;
84}
85
86static const Stmt *GetNextStmt(const ExplodedNode *N) {
87  for (N = GetSuccessorNode(N); N; N = GetSuccessorNode(N))
88    if (const Stmt *S = GetStmt(N->getLocation())) {
89      // Check if the statement is '?' or '&&'/'||'.  These are "merges",
90      // not actual statement points.
91      switch (S->getStmtClass()) {
92        case Stmt::ChooseExprClass:
93        case Stmt::BinaryConditionalOperatorClass: continue;
94        case Stmt::ConditionalOperatorClass: continue;
95        case Stmt::BinaryOperatorClass: {
96          BinaryOperatorKind Op = cast<BinaryOperator>(S)->getOpcode();
97          if (Op == BO_LAnd || Op == BO_LOr)
98            continue;
99          break;
100        }
101        default:
102          break;
103      }
104      return S;
105    }
106
107  return 0;
108}
109
110static inline const Stmt*
111GetCurrentOrPreviousStmt(const ExplodedNode *N) {
112  if (const Stmt *S = GetStmt(N->getLocation()))
113    return S;
114
115  return GetPreviousStmt(N);
116}
117
118static inline const Stmt*
119GetCurrentOrNextStmt(const ExplodedNode *N) {
120  if (const Stmt *S = GetStmt(N->getLocation()))
121    return S;
122
123  return GetNextStmt(N);
124}
125
126//===----------------------------------------------------------------------===//
127// Diagnostic cleanup.
128//===----------------------------------------------------------------------===//
129
130static PathDiagnosticEventPiece *
131eventsDescribeSameCondition(PathDiagnosticEventPiece *X,
132                            PathDiagnosticEventPiece *Y) {
133  // Prefer diagnostics that come from ConditionBRVisitor over
134  // those that came from TrackConstraintBRVisitor.
135  const void *tagPreferred = ConditionBRVisitor::getTag();
136  const void *tagLesser = TrackConstraintBRVisitor::getTag();
137
138  if (X->getLocation() != Y->getLocation())
139    return 0;
140
141  if (X->getTag() == tagPreferred && Y->getTag() == tagLesser)
142    return X;
143
144  if (Y->getTag() == tagPreferred && X->getTag() == tagLesser)
145    return Y;
146
147  return 0;
148}
149
150/// An optimization pass over PathPieces that removes redundant diagnostics
151/// generated by both ConditionBRVisitor and TrackConstraintBRVisitor.  Both
152/// BugReporterVisitors use different methods to generate diagnostics, with
153/// one capable of emitting diagnostics in some cases but not in others.  This
154/// can lead to redundant diagnostic pieces at the same point in a path.
155static void removeRedundantMsgs(PathPieces &path) {
156  unsigned N = path.size();
157  if (N < 2)
158    return;
159  // NOTE: this loop intentionally is not using an iterator.  Instead, we
160  // are streaming the path and modifying it in place.  This is done by
161  // grabbing the front, processing it, and if we decide to keep it append
162  // it to the end of the path.  The entire path is processed in this way.
163  for (unsigned i = 0; i < N; ++i) {
164    IntrusiveRefCntPtr<PathDiagnosticPiece> piece(path.front());
165    path.pop_front();
166
167    switch (piece->getKind()) {
168      case clang::ento::PathDiagnosticPiece::Call:
169        removeRedundantMsgs(cast<PathDiagnosticCallPiece>(piece)->path);
170        break;
171      case clang::ento::PathDiagnosticPiece::Macro:
172        removeRedundantMsgs(cast<PathDiagnosticMacroPiece>(piece)->subPieces);
173        break;
174      case clang::ento::PathDiagnosticPiece::ControlFlow:
175        break;
176      case clang::ento::PathDiagnosticPiece::Event: {
177        if (i == N-1)
178          break;
179
180        if (PathDiagnosticEventPiece *nextEvent =
181            dyn_cast<PathDiagnosticEventPiece>(path.front().getPtr())) {
182          PathDiagnosticEventPiece *event =
183            cast<PathDiagnosticEventPiece>(piece);
184          // Check to see if we should keep one of the two pieces.  If we
185          // come up with a preference, record which piece to keep, and consume
186          // another piece from the path.
187          if (PathDiagnosticEventPiece *pieceToKeep =
188              eventsDescribeSameCondition(event, nextEvent)) {
189            piece = pieceToKeep;
190            path.pop_front();
191            ++i;
192          }
193        }
194        break;
195      }
196    }
197    path.push_back(piece);
198  }
199}
200
201/// Recursively scan through a path and prune out calls and macros pieces
202/// that aren't needed.  Return true if afterwards the path contains
203/// "interesting stuff" which means it shouldn't be pruned from the parent path.
204bool BugReporter::RemoveUnneededCalls(PathPieces &pieces, BugReport *R) {
205  bool containsSomethingInteresting = false;
206  const unsigned N = pieces.size();
207
208  for (unsigned i = 0 ; i < N ; ++i) {
209    // Remove the front piece from the path.  If it is still something we
210    // want to keep once we are done, we will push it back on the end.
211    IntrusiveRefCntPtr<PathDiagnosticPiece> piece(pieces.front());
212    pieces.pop_front();
213
214    // Throw away pieces with invalid locations. Note that we can't throw away
215    // calls just yet because they might have something interesting inside them.
216    // If so, their locations will be adjusted as necessary later.
217    if (piece->getKind() != PathDiagnosticPiece::Call &&
218        piece->getLocation().asLocation().isInvalid())
219      continue;
220
221    switch (piece->getKind()) {
222      case PathDiagnosticPiece::Call: {
223        PathDiagnosticCallPiece *call = cast<PathDiagnosticCallPiece>(piece);
224        // Check if the location context is interesting.
225        assert(LocationContextMap.count(call));
226        if (R->isInteresting(LocationContextMap[call])) {
227          containsSomethingInteresting = true;
228          break;
229        }
230
231        if (!RemoveUnneededCalls(call->path, R))
232          continue;
233
234        containsSomethingInteresting = true;
235        break;
236      }
237      case PathDiagnosticPiece::Macro: {
238        PathDiagnosticMacroPiece *macro = cast<PathDiagnosticMacroPiece>(piece);
239        if (!RemoveUnneededCalls(macro->subPieces, R))
240          continue;
241        containsSomethingInteresting = true;
242        break;
243      }
244      case PathDiagnosticPiece::Event: {
245        PathDiagnosticEventPiece *event = cast<PathDiagnosticEventPiece>(piece);
246
247        // We never throw away an event, but we do throw it away wholesale
248        // as part of a path if we throw the entire path away.
249        containsSomethingInteresting |= !event->isPrunable();
250        break;
251      }
252      case PathDiagnosticPiece::ControlFlow:
253        break;
254    }
255
256    pieces.push_back(piece);
257  }
258
259  return containsSomethingInteresting;
260}
261
262/// Recursively scan through a path and make sure that all call pieces have
263/// valid locations. Note that all other pieces with invalid locations should
264/// have already been pruned out.
265static void adjustCallLocations(PathPieces &Pieces,
266                                PathDiagnosticLocation *LastCallLocation = 0) {
267  for (PathPieces::iterator I = Pieces.begin(), E = Pieces.end(); I != E; ++I) {
268    PathDiagnosticCallPiece *Call = dyn_cast<PathDiagnosticCallPiece>(*I);
269
270    if (!Call) {
271      assert((*I)->getLocation().asLocation().isValid());
272      continue;
273    }
274
275    if (LastCallLocation) {
276      if (!Call->callEnter.asLocation().isValid() ||
277          Call->getCaller()->isImplicit())
278        Call->callEnter = *LastCallLocation;
279      if (!Call->callReturn.asLocation().isValid() ||
280          Call->getCaller()->isImplicit())
281        Call->callReturn = *LastCallLocation;
282    }
283
284    // Recursively clean out the subclass.  Keep this call around if
285    // it contains any informative diagnostics.
286    PathDiagnosticLocation *ThisCallLocation;
287    if (Call->callEnterWithin.asLocation().isValid() &&
288        !Call->getCallee()->isImplicit())
289      ThisCallLocation = &Call->callEnterWithin;
290    else
291      ThisCallLocation = &Call->callEnter;
292
293    assert(ThisCallLocation && "Outermost call has an invalid location");
294    adjustCallLocations(Call->path, ThisCallLocation);
295  }
296}
297
298//===----------------------------------------------------------------------===//
299// PathDiagnosticBuilder and its associated routines and helper objects.
300//===----------------------------------------------------------------------===//
301
302namespace {
303class NodeMapClosure : public BugReport::NodeResolver {
304  InterExplodedGraphMap &M;
305public:
306  NodeMapClosure(InterExplodedGraphMap &m) : M(m) {}
307
308  const ExplodedNode *getOriginalNode(const ExplodedNode *N) {
309    return M.lookup(N);
310  }
311};
312
313class PathDiagnosticBuilder : public BugReporterContext {
314  BugReport *R;
315  PathDiagnosticConsumer *PDC;
316  NodeMapClosure NMC;
317public:
318  const LocationContext *LC;
319
320  PathDiagnosticBuilder(GRBugReporter &br,
321                        BugReport *r, InterExplodedGraphMap &Backmap,
322                        PathDiagnosticConsumer *pdc)
323    : BugReporterContext(br),
324      R(r), PDC(pdc), NMC(Backmap), LC(r->getErrorNode()->getLocationContext())
325  {}
326
327  PathDiagnosticLocation ExecutionContinues(const ExplodedNode *N);
328
329  PathDiagnosticLocation ExecutionContinues(llvm::raw_string_ostream &os,
330                                            const ExplodedNode *N);
331
332  BugReport *getBugReport() { return R; }
333
334  Decl const &getCodeDecl() { return R->getErrorNode()->getCodeDecl(); }
335
336  ParentMap& getParentMap() { return LC->getParentMap(); }
337
338  const Stmt *getParent(const Stmt *S) {
339    return getParentMap().getParent(S);
340  }
341
342  virtual NodeMapClosure& getNodeResolver() { return NMC; }
343
344  PathDiagnosticLocation getEnclosingStmtLocation(const Stmt *S);
345
346  PathDiagnosticConsumer::PathGenerationScheme getGenerationScheme() const {
347    return PDC ? PDC->getGenerationScheme() : PathDiagnosticConsumer::Extensive;
348  }
349
350  bool supportsLogicalOpControlFlow() const {
351    return PDC ? PDC->supportsLogicalOpControlFlow() : true;
352  }
353};
354} // end anonymous namespace
355
356PathDiagnosticLocation
357PathDiagnosticBuilder::ExecutionContinues(const ExplodedNode *N) {
358  if (const Stmt *S = GetNextStmt(N))
359    return PathDiagnosticLocation(S, getSourceManager(), LC);
360
361  return PathDiagnosticLocation::createDeclEnd(N->getLocationContext(),
362                                               getSourceManager());
363}
364
365PathDiagnosticLocation
366PathDiagnosticBuilder::ExecutionContinues(llvm::raw_string_ostream &os,
367                                          const ExplodedNode *N) {
368
369  // Slow, but probably doesn't matter.
370  if (os.str().empty())
371    os << ' ';
372
373  const PathDiagnosticLocation &Loc = ExecutionContinues(N);
374
375  if (Loc.asStmt())
376    os << "Execution continues on line "
377       << getSourceManager().getExpansionLineNumber(Loc.asLocation())
378       << '.';
379  else {
380    os << "Execution jumps to the end of the ";
381    const Decl *D = N->getLocationContext()->getDecl();
382    if (isa<ObjCMethodDecl>(D))
383      os << "method";
384    else if (isa<FunctionDecl>(D))
385      os << "function";
386    else {
387      assert(isa<BlockDecl>(D));
388      os << "anonymous block";
389    }
390    os << '.';
391  }
392
393  return Loc;
394}
395
396static bool IsNested(const Stmt *S, ParentMap &PM) {
397  if (isa<Expr>(S) && PM.isConsumedExpr(cast<Expr>(S)))
398    return true;
399
400  const Stmt *Parent = PM.getParentIgnoreParens(S);
401
402  if (Parent)
403    switch (Parent->getStmtClass()) {
404      case Stmt::ForStmtClass:
405      case Stmt::DoStmtClass:
406      case Stmt::WhileStmtClass:
407        return true;
408      default:
409        break;
410    }
411
412  return false;
413}
414
415PathDiagnosticLocation
416PathDiagnosticBuilder::getEnclosingStmtLocation(const Stmt *S) {
417  assert(S && "Null Stmt *passed to getEnclosingStmtLocation");
418  ParentMap &P = getParentMap();
419  SourceManager &SMgr = getSourceManager();
420
421  while (IsNested(S, P)) {
422    const Stmt *Parent = P.getParentIgnoreParens(S);
423
424    if (!Parent)
425      break;
426
427    switch (Parent->getStmtClass()) {
428      case Stmt::BinaryOperatorClass: {
429        const BinaryOperator *B = cast<BinaryOperator>(Parent);
430        if (B->isLogicalOp())
431          return PathDiagnosticLocation(S, SMgr, LC);
432        break;
433      }
434      case Stmt::CompoundStmtClass:
435      case Stmt::StmtExprClass:
436        return PathDiagnosticLocation(S, SMgr, LC);
437      case Stmt::ChooseExprClass:
438        // Similar to '?' if we are referring to condition, just have the edge
439        // point to the entire choose expression.
440        if (cast<ChooseExpr>(Parent)->getCond() == S)
441          return PathDiagnosticLocation(Parent, SMgr, LC);
442        else
443          return PathDiagnosticLocation(S, SMgr, LC);
444      case Stmt::BinaryConditionalOperatorClass:
445      case Stmt::ConditionalOperatorClass:
446        // For '?', if we are referring to condition, just have the edge point
447        // to the entire '?' expression.
448        if (cast<AbstractConditionalOperator>(Parent)->getCond() == S)
449          return PathDiagnosticLocation(Parent, SMgr, LC);
450        else
451          return PathDiagnosticLocation(S, SMgr, LC);
452      case Stmt::DoStmtClass:
453          return PathDiagnosticLocation(S, SMgr, LC);
454      case Stmt::ForStmtClass:
455        if (cast<ForStmt>(Parent)->getBody() == S)
456          return PathDiagnosticLocation(S, SMgr, LC);
457        break;
458      case Stmt::IfStmtClass:
459        if (cast<IfStmt>(Parent)->getCond() != S)
460          return PathDiagnosticLocation(S, SMgr, LC);
461        break;
462      case Stmt::ObjCForCollectionStmtClass:
463        if (cast<ObjCForCollectionStmt>(Parent)->getBody() == S)
464          return PathDiagnosticLocation(S, SMgr, LC);
465        break;
466      case Stmt::WhileStmtClass:
467        if (cast<WhileStmt>(Parent)->getCond() != S)
468          return PathDiagnosticLocation(S, SMgr, LC);
469        break;
470      default:
471        break;
472    }
473
474    S = Parent;
475  }
476
477  assert(S && "Cannot have null Stmt for PathDiagnosticLocation");
478
479  // Special case: DeclStmts can appear in for statement declarations, in which
480  //  case the ForStmt is the context.
481  if (isa<DeclStmt>(S)) {
482    if (const Stmt *Parent = P.getParent(S)) {
483      switch (Parent->getStmtClass()) {
484        case Stmt::ForStmtClass:
485        case Stmt::ObjCForCollectionStmtClass:
486          return PathDiagnosticLocation(Parent, SMgr, LC);
487        default:
488          break;
489      }
490    }
491  }
492  else if (isa<BinaryOperator>(S)) {
493    // Special case: the binary operator represents the initialization
494    // code in a for statement (this can happen when the variable being
495    // initialized is an old variable.
496    if (const ForStmt *FS =
497          dyn_cast_or_null<ForStmt>(P.getParentIgnoreParens(S))) {
498      if (FS->getInit() == S)
499        return PathDiagnosticLocation(FS, SMgr, LC);
500    }
501  }
502
503  return PathDiagnosticLocation(S, SMgr, LC);
504}
505
506//===----------------------------------------------------------------------===//
507// "Visitors only" path diagnostic generation algorithm.
508//===----------------------------------------------------------------------===//
509static bool GenerateVisitorsOnlyPathDiagnostic(PathDiagnostic &PD,
510                                               PathDiagnosticBuilder &PDB,
511                                               const ExplodedNode *N,
512                                      ArrayRef<BugReporterVisitor *> visitors) {
513  // All path generation skips the very first node (the error node).
514  // This is because there is special handling for the end-of-path note.
515  N = N->getFirstPred();
516  if (!N)
517    return true;
518
519  BugReport *R = PDB.getBugReport();
520  while (const ExplodedNode *Pred = N->getFirstPred()) {
521    for (ArrayRef<BugReporterVisitor *>::iterator I = visitors.begin(),
522                                                  E = visitors.end();
523         I != E; ++I) {
524      // Visit all the node pairs, but throw the path pieces away.
525      PathDiagnosticPiece *Piece = (*I)->VisitNode(N, Pred, PDB, *R);
526      delete Piece;
527    }
528
529    N = Pred;
530  }
531
532  return R->isValid();
533}
534
535//===----------------------------------------------------------------------===//
536// "Minimal" path diagnostic generation algorithm.
537//===----------------------------------------------------------------------===//
538typedef std::pair<PathDiagnosticCallPiece*, const ExplodedNode*> StackDiagPair;
539typedef SmallVector<StackDiagPair, 6> StackDiagVector;
540
541static void updateStackPiecesWithMessage(PathDiagnosticPiece *P,
542                                         StackDiagVector &CallStack) {
543  // If the piece contains a special message, add it to all the call
544  // pieces on the active stack.
545  if (PathDiagnosticEventPiece *ep =
546        dyn_cast<PathDiagnosticEventPiece>(P)) {
547
548    if (ep->hasCallStackHint())
549      for (StackDiagVector::iterator I = CallStack.begin(),
550                                     E = CallStack.end(); I != E; ++I) {
551        PathDiagnosticCallPiece *CP = I->first;
552        const ExplodedNode *N = I->second;
553        std::string stackMsg = ep->getCallStackMessage(N);
554
555        // The last message on the path to final bug is the most important
556        // one. Since we traverse the path backwards, do not add the message
557        // if one has been previously added.
558        if  (!CP->hasCallStackMessage())
559          CP->setCallStackMessage(stackMsg);
560      }
561  }
562}
563
564static void CompactPathDiagnostic(PathPieces &path, const SourceManager& SM);
565
566static bool GenerateMinimalPathDiagnostic(PathDiagnostic& PD,
567                                          PathDiagnosticBuilder &PDB,
568                                          const ExplodedNode *N,
569                                      ArrayRef<BugReporterVisitor *> visitors) {
570
571  SourceManager& SMgr = PDB.getSourceManager();
572  const LocationContext *LC = PDB.LC;
573  const ExplodedNode *NextNode = N->pred_empty()
574                                        ? NULL : *(N->pred_begin());
575
576  StackDiagVector CallStack;
577
578  while (NextNode) {
579    N = NextNode;
580    PDB.LC = N->getLocationContext();
581    NextNode = GetPredecessorNode(N);
582
583    ProgramPoint P = N->getLocation();
584
585    do {
586      if (Optional<CallExitEnd> CE = P.getAs<CallExitEnd>()) {
587        PathDiagnosticCallPiece *C =
588            PathDiagnosticCallPiece::construct(N, *CE, SMgr);
589        GRBugReporter& BR = PDB.getBugReporter();
590        BR.addCallPieceLocationContextPair(C, CE->getCalleeContext());
591        PD.getActivePath().push_front(C);
592        PD.pushActivePath(&C->path);
593        CallStack.push_back(StackDiagPair(C, N));
594        break;
595      }
596
597      if (Optional<CallEnter> CE = P.getAs<CallEnter>()) {
598        // Flush all locations, and pop the active path.
599        bool VisitedEntireCall = PD.isWithinCall();
600        PD.popActivePath();
601
602        // Either we just added a bunch of stuff to the top-level path, or
603        // we have a previous CallExitEnd.  If the former, it means that the
604        // path terminated within a function call.  We must then take the
605        // current contents of the active path and place it within
606        // a new PathDiagnosticCallPiece.
607        PathDiagnosticCallPiece *C;
608        if (VisitedEntireCall) {
609          C = cast<PathDiagnosticCallPiece>(PD.getActivePath().front());
610        } else {
611          const Decl *Caller = CE->getLocationContext()->getDecl();
612          C = PathDiagnosticCallPiece::construct(PD.getActivePath(), Caller);
613          GRBugReporter& BR = PDB.getBugReporter();
614          BR.addCallPieceLocationContextPair(C, CE->getCalleeContext());
615        }
616
617        C->setCallee(*CE, SMgr);
618        if (!CallStack.empty()) {
619          assert(CallStack.back().first == C);
620          CallStack.pop_back();
621        }
622        break;
623      }
624
625      if (Optional<BlockEdge> BE = P.getAs<BlockEdge>()) {
626        const CFGBlock *Src = BE->getSrc();
627        const CFGBlock *Dst = BE->getDst();
628        const Stmt *T = Src->getTerminator();
629
630        if (!T)
631          break;
632
633        PathDiagnosticLocation Start =
634            PathDiagnosticLocation::createBegin(T, SMgr,
635                N->getLocationContext());
636
637        switch (T->getStmtClass()) {
638        default:
639          break;
640
641        case Stmt::GotoStmtClass:
642        case Stmt::IndirectGotoStmtClass: {
643          const Stmt *S = GetNextStmt(N);
644
645          if (!S)
646            break;
647
648          std::string sbuf;
649          llvm::raw_string_ostream os(sbuf);
650          const PathDiagnosticLocation &End = PDB.getEnclosingStmtLocation(S);
651
652          os << "Control jumps to line "
653              << End.asLocation().getExpansionLineNumber();
654          PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
655              Start, End, os.str()));
656          break;
657        }
658
659        case Stmt::SwitchStmtClass: {
660          // Figure out what case arm we took.
661          std::string sbuf;
662          llvm::raw_string_ostream os(sbuf);
663
664          if (const Stmt *S = Dst->getLabel()) {
665            PathDiagnosticLocation End(S, SMgr, LC);
666
667            switch (S->getStmtClass()) {
668            default:
669              os << "No cases match in the switch statement. "
670              "Control jumps to line "
671              << End.asLocation().getExpansionLineNumber();
672              break;
673            case Stmt::DefaultStmtClass:
674              os << "Control jumps to the 'default' case at line "
675              << End.asLocation().getExpansionLineNumber();
676              break;
677
678            case Stmt::CaseStmtClass: {
679              os << "Control jumps to 'case ";
680              const CaseStmt *Case = cast<CaseStmt>(S);
681              const Expr *LHS = Case->getLHS()->IgnoreParenCasts();
682
683              // Determine if it is an enum.
684              bool GetRawInt = true;
685
686              if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(LHS)) {
687                // FIXME: Maybe this should be an assertion.  Are there cases
688                // were it is not an EnumConstantDecl?
689                const EnumConstantDecl *D =
690                    dyn_cast<EnumConstantDecl>(DR->getDecl());
691
692                if (D) {
693                  GetRawInt = false;
694                  os << *D;
695                }
696              }
697
698              if (GetRawInt)
699                os << LHS->EvaluateKnownConstInt(PDB.getASTContext());
700
701              os << ":'  at line "
702                  << End.asLocation().getExpansionLineNumber();
703              break;
704            }
705            }
706            PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
707                Start, End, os.str()));
708          }
709          else {
710            os << "'Default' branch taken. ";
711            const PathDiagnosticLocation &End = PDB.ExecutionContinues(os, N);
712            PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
713                Start, End, os.str()));
714          }
715
716          break;
717        }
718
719        case Stmt::BreakStmtClass:
720        case Stmt::ContinueStmtClass: {
721          std::string sbuf;
722          llvm::raw_string_ostream os(sbuf);
723          PathDiagnosticLocation End = PDB.ExecutionContinues(os, N);
724          PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
725              Start, End, os.str()));
726          break;
727        }
728
729        // Determine control-flow for ternary '?'.
730        case Stmt::BinaryConditionalOperatorClass:
731        case Stmt::ConditionalOperatorClass: {
732          std::string sbuf;
733          llvm::raw_string_ostream os(sbuf);
734          os << "'?' condition is ";
735
736          if (*(Src->succ_begin()+1) == Dst)
737            os << "false";
738          else
739            os << "true";
740
741          PathDiagnosticLocation End = PDB.ExecutionContinues(N);
742
743          if (const Stmt *S = End.asStmt())
744            End = PDB.getEnclosingStmtLocation(S);
745
746          PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
747              Start, End, os.str()));
748          break;
749        }
750
751        // Determine control-flow for short-circuited '&&' and '||'.
752        case Stmt::BinaryOperatorClass: {
753          if (!PDB.supportsLogicalOpControlFlow())
754            break;
755
756          const BinaryOperator *B = cast<BinaryOperator>(T);
757          std::string sbuf;
758          llvm::raw_string_ostream os(sbuf);
759          os << "Left side of '";
760
761          if (B->getOpcode() == BO_LAnd) {
762            os << "&&" << "' is ";
763
764            if (*(Src->succ_begin()+1) == Dst) {
765              os << "false";
766              PathDiagnosticLocation End(B->getLHS(), SMgr, LC);
767              PathDiagnosticLocation Start =
768                  PathDiagnosticLocation::createOperatorLoc(B, SMgr);
769              PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
770                  Start, End, os.str()));
771            }
772            else {
773              os << "true";
774              PathDiagnosticLocation Start(B->getLHS(), SMgr, LC);
775              PathDiagnosticLocation End = PDB.ExecutionContinues(N);
776              PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
777                  Start, End, os.str()));
778            }
779          }
780          else {
781            assert(B->getOpcode() == BO_LOr);
782            os << "||" << "' is ";
783
784            if (*(Src->succ_begin()+1) == Dst) {
785              os << "false";
786              PathDiagnosticLocation Start(B->getLHS(), SMgr, LC);
787              PathDiagnosticLocation End = PDB.ExecutionContinues(N);
788              PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
789                  Start, End, os.str()));
790            }
791            else {
792              os << "true";
793              PathDiagnosticLocation End(B->getLHS(), SMgr, LC);
794              PathDiagnosticLocation Start =
795                  PathDiagnosticLocation::createOperatorLoc(B, SMgr);
796              PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
797                  Start, End, os.str()));
798            }
799          }
800
801          break;
802        }
803
804        case Stmt::DoStmtClass:  {
805          if (*(Src->succ_begin()) == Dst) {
806            std::string sbuf;
807            llvm::raw_string_ostream os(sbuf);
808
809            os << "Loop condition is true. ";
810            PathDiagnosticLocation End = PDB.ExecutionContinues(os, N);
811
812            if (const Stmt *S = End.asStmt())
813              End = PDB.getEnclosingStmtLocation(S);
814
815            PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
816                Start, End, os.str()));
817          }
818          else {
819            PathDiagnosticLocation End = PDB.ExecutionContinues(N);
820
821            if (const Stmt *S = End.asStmt())
822              End = PDB.getEnclosingStmtLocation(S);
823
824            PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
825                Start, End, "Loop condition is false.  Exiting loop"));
826          }
827
828          break;
829        }
830
831        case Stmt::WhileStmtClass:
832        case Stmt::ForStmtClass: {
833          if (*(Src->succ_begin()+1) == Dst) {
834            std::string sbuf;
835            llvm::raw_string_ostream os(sbuf);
836
837            os << "Loop condition is false. ";
838            PathDiagnosticLocation End = PDB.ExecutionContinues(os, N);
839            if (const Stmt *S = End.asStmt())
840              End = PDB.getEnclosingStmtLocation(S);
841
842            PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
843                Start, End, os.str()));
844          }
845          else {
846            PathDiagnosticLocation End = PDB.ExecutionContinues(N);
847            if (const Stmt *S = End.asStmt())
848              End = PDB.getEnclosingStmtLocation(S);
849
850            PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
851                Start, End, "Loop condition is true.  Entering loop body"));
852          }
853
854          break;
855        }
856
857        case Stmt::IfStmtClass: {
858          PathDiagnosticLocation End = PDB.ExecutionContinues(N);
859
860          if (const Stmt *S = End.asStmt())
861            End = PDB.getEnclosingStmtLocation(S);
862
863          if (*(Src->succ_begin()+1) == Dst)
864            PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
865                Start, End, "Taking false branch"));
866          else
867            PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
868                Start, End, "Taking true branch"));
869
870          break;
871        }
872        }
873      }
874    } while(0);
875
876    if (NextNode) {
877      // Add diagnostic pieces from custom visitors.
878      BugReport *R = PDB.getBugReport();
879      for (ArrayRef<BugReporterVisitor *>::iterator I = visitors.begin(),
880                                                    E = visitors.end();
881           I != E; ++I) {
882        if (PathDiagnosticPiece *p = (*I)->VisitNode(N, NextNode, PDB, *R)) {
883          PD.getActivePath().push_front(p);
884          updateStackPiecesWithMessage(p, CallStack);
885        }
886      }
887    }
888  }
889
890  if (!PDB.getBugReport()->isValid())
891    return false;
892
893  // After constructing the full PathDiagnostic, do a pass over it to compact
894  // PathDiagnosticPieces that occur within a macro.
895  CompactPathDiagnostic(PD.getMutablePieces(), PDB.getSourceManager());
896  return true;
897}
898
899//===----------------------------------------------------------------------===//
900// "Extensive" PathDiagnostic generation.
901//===----------------------------------------------------------------------===//
902
903static bool IsControlFlowExpr(const Stmt *S) {
904  const Expr *E = dyn_cast<Expr>(S);
905
906  if (!E)
907    return false;
908
909  E = E->IgnoreParenCasts();
910
911  if (isa<AbstractConditionalOperator>(E))
912    return true;
913
914  if (const BinaryOperator *B = dyn_cast<BinaryOperator>(E))
915    if (B->isLogicalOp())
916      return true;
917
918  return false;
919}
920
921namespace {
922class ContextLocation : public PathDiagnosticLocation {
923  bool IsDead;
924public:
925  ContextLocation(const PathDiagnosticLocation &L, bool isdead = false)
926    : PathDiagnosticLocation(L), IsDead(isdead) {}
927
928  void markDead() { IsDead = true; }
929  bool isDead() const { return IsDead; }
930};
931
932class EdgeBuilder {
933  std::vector<ContextLocation> CLocs;
934  typedef std::vector<ContextLocation>::iterator iterator;
935  PathDiagnostic &PD;
936  PathDiagnosticBuilder &PDB;
937  PathDiagnosticLocation PrevLoc;
938
939  bool IsConsumedExpr(const PathDiagnosticLocation &L);
940
941  bool containsLocation(const PathDiagnosticLocation &Container,
942                        const PathDiagnosticLocation &Containee);
943
944  PathDiagnosticLocation getContextLocation(const PathDiagnosticLocation &L);
945
946  PathDiagnosticLocation cleanUpLocation(PathDiagnosticLocation L,
947                                         bool firstCharOnly = false) {
948    if (const Stmt *S = L.asStmt()) {
949      const Stmt *Original = S;
950      while (1) {
951        // Adjust the location for some expressions that are best referenced
952        // by one of their subexpressions.
953        switch (S->getStmtClass()) {
954          default:
955            break;
956          case Stmt::ParenExprClass:
957          case Stmt::GenericSelectionExprClass:
958            S = cast<Expr>(S)->IgnoreParens();
959            firstCharOnly = true;
960            continue;
961          case Stmt::BinaryConditionalOperatorClass:
962          case Stmt::ConditionalOperatorClass:
963            S = cast<AbstractConditionalOperator>(S)->getCond();
964            firstCharOnly = true;
965            continue;
966          case Stmt::ChooseExprClass:
967            S = cast<ChooseExpr>(S)->getCond();
968            firstCharOnly = true;
969            continue;
970          case Stmt::BinaryOperatorClass:
971            S = cast<BinaryOperator>(S)->getLHS();
972            firstCharOnly = true;
973            continue;
974        }
975
976        break;
977      }
978
979      if (S != Original)
980        L = PathDiagnosticLocation(S, L.getManager(), PDB.LC);
981    }
982
983    if (firstCharOnly)
984      L  = PathDiagnosticLocation::createSingleLocation(L);
985
986    return L;
987  }
988
989  void popLocation() {
990    if (!CLocs.back().isDead() && CLocs.back().asLocation().isFileID()) {
991      // For contexts, we only one the first character as the range.
992      rawAddEdge(cleanUpLocation(CLocs.back(), true));
993    }
994    CLocs.pop_back();
995  }
996
997public:
998  EdgeBuilder(PathDiagnostic &pd, PathDiagnosticBuilder &pdb)
999    : PD(pd), PDB(pdb) {
1000
1001      // If the PathDiagnostic already has pieces, add the enclosing statement
1002      // of the first piece as a context as well.
1003      if (!PD.path.empty()) {
1004        PrevLoc = (*PD.path.begin())->getLocation();
1005
1006        if (const Stmt *S = PrevLoc.asStmt())
1007          addExtendedContext(PDB.getEnclosingStmtLocation(S).asStmt());
1008      }
1009  }
1010
1011  ~EdgeBuilder() {
1012    while (!CLocs.empty()) popLocation();
1013
1014    // Finally, add an initial edge from the start location of the first
1015    // statement (if it doesn't already exist).
1016    PathDiagnosticLocation L = PathDiagnosticLocation::createDeclBegin(
1017                                                       PDB.LC,
1018                                                       PDB.getSourceManager());
1019    if (L.isValid())
1020      rawAddEdge(L);
1021  }
1022
1023  void flushLocations() {
1024    while (!CLocs.empty())
1025      popLocation();
1026    PrevLoc = PathDiagnosticLocation();
1027  }
1028
1029  void addEdge(PathDiagnosticLocation NewLoc, bool alwaysAdd = false);
1030
1031  void rawAddEdge(PathDiagnosticLocation NewLoc);
1032
1033  void addContext(const Stmt *S);
1034  void addContext(const PathDiagnosticLocation &L);
1035  void addExtendedContext(const Stmt *S);
1036};
1037} // end anonymous namespace
1038
1039
1040PathDiagnosticLocation
1041EdgeBuilder::getContextLocation(const PathDiagnosticLocation &L) {
1042  if (const Stmt *S = L.asStmt()) {
1043    if (IsControlFlowExpr(S))
1044      return L;
1045
1046    return PDB.getEnclosingStmtLocation(S);
1047  }
1048
1049  return L;
1050}
1051
1052bool EdgeBuilder::containsLocation(const PathDiagnosticLocation &Container,
1053                                   const PathDiagnosticLocation &Containee) {
1054
1055  if (Container == Containee)
1056    return true;
1057
1058  if (Container.asDecl())
1059    return true;
1060
1061  if (const Stmt *S = Containee.asStmt())
1062    if (const Stmt *ContainerS = Container.asStmt()) {
1063      while (S) {
1064        if (S == ContainerS)
1065          return true;
1066        S = PDB.getParent(S);
1067      }
1068      return false;
1069    }
1070
1071  // Less accurate: compare using source ranges.
1072  SourceRange ContainerR = Container.asRange();
1073  SourceRange ContaineeR = Containee.asRange();
1074
1075  SourceManager &SM = PDB.getSourceManager();
1076  SourceLocation ContainerRBeg = SM.getExpansionLoc(ContainerR.getBegin());
1077  SourceLocation ContainerREnd = SM.getExpansionLoc(ContainerR.getEnd());
1078  SourceLocation ContaineeRBeg = SM.getExpansionLoc(ContaineeR.getBegin());
1079  SourceLocation ContaineeREnd = SM.getExpansionLoc(ContaineeR.getEnd());
1080
1081  unsigned ContainerBegLine = SM.getExpansionLineNumber(ContainerRBeg);
1082  unsigned ContainerEndLine = SM.getExpansionLineNumber(ContainerREnd);
1083  unsigned ContaineeBegLine = SM.getExpansionLineNumber(ContaineeRBeg);
1084  unsigned ContaineeEndLine = SM.getExpansionLineNumber(ContaineeREnd);
1085
1086  assert(ContainerBegLine <= ContainerEndLine);
1087  assert(ContaineeBegLine <= ContaineeEndLine);
1088
1089  return (ContainerBegLine <= ContaineeBegLine &&
1090          ContainerEndLine >= ContaineeEndLine &&
1091          (ContainerBegLine != ContaineeBegLine ||
1092           SM.getExpansionColumnNumber(ContainerRBeg) <=
1093           SM.getExpansionColumnNumber(ContaineeRBeg)) &&
1094          (ContainerEndLine != ContaineeEndLine ||
1095           SM.getExpansionColumnNumber(ContainerREnd) >=
1096           SM.getExpansionColumnNumber(ContaineeREnd)));
1097}
1098
1099void EdgeBuilder::rawAddEdge(PathDiagnosticLocation NewLoc) {
1100  if (!PrevLoc.isValid()) {
1101    PrevLoc = NewLoc;
1102    return;
1103  }
1104
1105  const PathDiagnosticLocation &NewLocClean = cleanUpLocation(NewLoc);
1106  const PathDiagnosticLocation &PrevLocClean = cleanUpLocation(PrevLoc);
1107
1108  if (PrevLocClean.asLocation().isInvalid()) {
1109    PrevLoc = NewLoc;
1110    return;
1111  }
1112
1113  if (NewLocClean.asLocation() == PrevLocClean.asLocation())
1114    return;
1115
1116  // FIXME: Ignore intra-macro edges for now.
1117  if (NewLocClean.asLocation().getExpansionLoc() ==
1118      PrevLocClean.asLocation().getExpansionLoc())
1119    return;
1120
1121  PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(NewLocClean, PrevLocClean));
1122  PrevLoc = NewLoc;
1123}
1124
1125void EdgeBuilder::addEdge(PathDiagnosticLocation NewLoc, bool alwaysAdd) {
1126
1127  if (!alwaysAdd && NewLoc.asLocation().isMacroID())
1128    return;
1129
1130  const PathDiagnosticLocation &CLoc = getContextLocation(NewLoc);
1131
1132  while (!CLocs.empty()) {
1133    ContextLocation &TopContextLoc = CLocs.back();
1134
1135    // Is the top location context the same as the one for the new location?
1136    if (TopContextLoc == CLoc) {
1137      if (alwaysAdd) {
1138        if (IsConsumedExpr(TopContextLoc) &&
1139            !IsControlFlowExpr(TopContextLoc.asStmt()))
1140            TopContextLoc.markDead();
1141
1142        rawAddEdge(NewLoc);
1143      }
1144
1145      return;
1146    }
1147
1148    if (containsLocation(TopContextLoc, CLoc)) {
1149      if (alwaysAdd) {
1150        rawAddEdge(NewLoc);
1151
1152        if (IsConsumedExpr(CLoc) && !IsControlFlowExpr(CLoc.asStmt())) {
1153          CLocs.push_back(ContextLocation(CLoc, true));
1154          return;
1155        }
1156      }
1157
1158      CLocs.push_back(CLoc);
1159      return;
1160    }
1161
1162    // Context does not contain the location.  Flush it.
1163    popLocation();
1164  }
1165
1166  // If we reach here, there is no enclosing context.  Just add the edge.
1167  rawAddEdge(NewLoc);
1168}
1169
1170bool EdgeBuilder::IsConsumedExpr(const PathDiagnosticLocation &L) {
1171  if (const Expr *X = dyn_cast_or_null<Expr>(L.asStmt()))
1172    return PDB.getParentMap().isConsumedExpr(X) && !IsControlFlowExpr(X);
1173
1174  return false;
1175}
1176
1177void EdgeBuilder::addExtendedContext(const Stmt *S) {
1178  if (!S)
1179    return;
1180
1181  const Stmt *Parent = PDB.getParent(S);
1182  while (Parent) {
1183    if (isa<CompoundStmt>(Parent))
1184      Parent = PDB.getParent(Parent);
1185    else
1186      break;
1187  }
1188
1189  if (Parent) {
1190    switch (Parent->getStmtClass()) {
1191      case Stmt::DoStmtClass:
1192      case Stmt::ObjCAtSynchronizedStmtClass:
1193        addContext(Parent);
1194      default:
1195        break;
1196    }
1197  }
1198
1199  addContext(S);
1200}
1201
1202void EdgeBuilder::addContext(const Stmt *S) {
1203  if (!S)
1204    return;
1205
1206  PathDiagnosticLocation L(S, PDB.getSourceManager(), PDB.LC);
1207  addContext(L);
1208}
1209
1210void EdgeBuilder::addContext(const PathDiagnosticLocation &L) {
1211  while (!CLocs.empty()) {
1212    const PathDiagnosticLocation &TopContextLoc = CLocs.back();
1213
1214    // Is the top location context the same as the one for the new location?
1215    if (TopContextLoc == L)
1216      return;
1217
1218    if (containsLocation(TopContextLoc, L)) {
1219      CLocs.push_back(L);
1220      return;
1221    }
1222
1223    // Context does not contain the location.  Flush it.
1224    popLocation();
1225  }
1226
1227  CLocs.push_back(L);
1228}
1229
1230// Cone-of-influence: support the reverse propagation of "interesting" symbols
1231// and values by tracing interesting calculations backwards through evaluated
1232// expressions along a path.  This is probably overly complicated, but the idea
1233// is that if an expression computed an "interesting" value, the child
1234// expressions are are also likely to be "interesting" as well (which then
1235// propagates to the values they in turn compute).  This reverse propagation
1236// is needed to track interesting correlations across function call boundaries,
1237// where formal arguments bind to actual arguments, etc.  This is also needed
1238// because the constraint solver sometimes simplifies certain symbolic values
1239// into constants when appropriate, and this complicates reasoning about
1240// interesting values.
1241typedef llvm::DenseSet<const Expr *> InterestingExprs;
1242
1243static void reversePropagateIntererstingSymbols(BugReport &R,
1244                                                InterestingExprs &IE,
1245                                                const ProgramState *State,
1246                                                const Expr *Ex,
1247                                                const LocationContext *LCtx) {
1248  SVal V = State->getSVal(Ex, LCtx);
1249  if (!(R.isInteresting(V) || IE.count(Ex)))
1250    return;
1251
1252  switch (Ex->getStmtClass()) {
1253    default:
1254      if (!isa<CastExpr>(Ex))
1255        break;
1256      // Fall through.
1257    case Stmt::BinaryOperatorClass:
1258    case Stmt::UnaryOperatorClass: {
1259      for (Stmt::const_child_iterator CI = Ex->child_begin(),
1260            CE = Ex->child_end();
1261            CI != CE; ++CI) {
1262        if (const Expr *child = dyn_cast_or_null<Expr>(*CI)) {
1263          IE.insert(child);
1264          SVal ChildV = State->getSVal(child, LCtx);
1265          R.markInteresting(ChildV);
1266        }
1267        break;
1268      }
1269    }
1270  }
1271
1272  R.markInteresting(V);
1273}
1274
1275static void reversePropagateInterestingSymbols(BugReport &R,
1276                                               InterestingExprs &IE,
1277                                               const ProgramState *State,
1278                                               const LocationContext *CalleeCtx,
1279                                               const LocationContext *CallerCtx)
1280{
1281  // FIXME: Handle non-CallExpr-based CallEvents.
1282  const StackFrameContext *Callee = CalleeCtx->getCurrentStackFrame();
1283  const Stmt *CallSite = Callee->getCallSite();
1284  if (const CallExpr *CE = dyn_cast_or_null<CallExpr>(CallSite)) {
1285    if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CalleeCtx->getDecl())) {
1286      FunctionDecl::param_const_iterator PI = FD->param_begin(),
1287                                         PE = FD->param_end();
1288      CallExpr::const_arg_iterator AI = CE->arg_begin(), AE = CE->arg_end();
1289      for (; AI != AE && PI != PE; ++AI, ++PI) {
1290        if (const Expr *ArgE = *AI) {
1291          if (const ParmVarDecl *PD = *PI) {
1292            Loc LV = State->getLValue(PD, CalleeCtx);
1293            if (R.isInteresting(LV) || R.isInteresting(State->getRawSVal(LV)))
1294              IE.insert(ArgE);
1295          }
1296        }
1297      }
1298    }
1299  }
1300}
1301
1302//===----------------------------------------------------------------------===//
1303// Functions for determining if a loop was executed 0 times.
1304//===----------------------------------------------------------------------===//
1305
1306/// Return true if the terminator is a loop and the destination is the
1307/// false branch.
1308static bool isLoopJumpPastBody(const Stmt *Term, const BlockEdge *BE) {
1309  switch (Term->getStmtClass()) {
1310    case Stmt::ForStmtClass:
1311    case Stmt::WhileStmtClass:
1312    case Stmt::ObjCForCollectionStmtClass:
1313      break;
1314    default:
1315      // Note that we intentionally do not include do..while here.
1316      return false;
1317  }
1318
1319  // Did we take the false branch?
1320  const CFGBlock *Src = BE->getSrc();
1321  assert(Src->succ_size() == 2);
1322  return (*(Src->succ_begin()+1) == BE->getDst());
1323}
1324
1325static bool isContainedByStmt(ParentMap &PM, const Stmt *S, const Stmt *SubS) {
1326  while (SubS) {
1327    if (SubS == S)
1328      return true;
1329    SubS = PM.getParent(SubS);
1330  }
1331  return false;
1332}
1333
1334static const Stmt *getStmtBeforeCond(ParentMap &PM, const Stmt *Term,
1335                                     const ExplodedNode *N) {
1336  while (N) {
1337    Optional<StmtPoint> SP = N->getLocation().getAs<StmtPoint>();
1338    if (SP) {
1339      const Stmt *S = SP->getStmt();
1340      if (!isContainedByStmt(PM, Term, S))
1341        return S;
1342    }
1343    N = GetPredecessorNode(N);
1344  }
1345  return 0;
1346}
1347
1348static bool isInLoopBody(ParentMap &PM, const Stmt *S, const Stmt *Term) {
1349  const Stmt *LoopBody = 0;
1350  switch (Term->getStmtClass()) {
1351    case Stmt::ForStmtClass: {
1352      const ForStmt *FS = cast<ForStmt>(Term);
1353      if (isContainedByStmt(PM, FS->getInc(), S))
1354        return true;
1355      LoopBody = FS->getBody();
1356      break;
1357    }
1358    case Stmt::ObjCForCollectionStmtClass: {
1359      const ObjCForCollectionStmt *FC = cast<ObjCForCollectionStmt>(Term);
1360      LoopBody = FC->getBody();
1361      break;
1362    }
1363    case Stmt::WhileStmtClass:
1364      LoopBody = cast<WhileStmt>(Term)->getBody();
1365      break;
1366    default:
1367      return false;
1368  }
1369  return isContainedByStmt(PM, LoopBody, S);
1370}
1371
1372//===----------------------------------------------------------------------===//
1373// Top-level logic for generating extensive path diagnostics.
1374//===----------------------------------------------------------------------===//
1375
1376static bool GenerateExtensivePathDiagnostic(PathDiagnostic& PD,
1377                                            PathDiagnosticBuilder &PDB,
1378                                            const ExplodedNode *N,
1379                                      ArrayRef<BugReporterVisitor *> visitors) {
1380  EdgeBuilder EB(PD, PDB);
1381  const SourceManager& SM = PDB.getSourceManager();
1382  StackDiagVector CallStack;
1383  InterestingExprs IE;
1384
1385  const ExplodedNode *NextNode = N->pred_empty() ? NULL : *(N->pred_begin());
1386  while (NextNode) {
1387    N = NextNode;
1388    NextNode = GetPredecessorNode(N);
1389    ProgramPoint P = N->getLocation();
1390
1391    do {
1392      if (Optional<PostStmt> PS = P.getAs<PostStmt>()) {
1393        if (const Expr *Ex = PS->getStmtAs<Expr>())
1394          reversePropagateIntererstingSymbols(*PDB.getBugReport(), IE,
1395                                              N->getState().getPtr(), Ex,
1396                                              N->getLocationContext());
1397      }
1398
1399      if (Optional<CallExitEnd> CE = P.getAs<CallExitEnd>()) {
1400        const Stmt *S = CE->getCalleeContext()->getCallSite();
1401        if (const Expr *Ex = dyn_cast_or_null<Expr>(S)) {
1402            reversePropagateIntererstingSymbols(*PDB.getBugReport(), IE,
1403                                                N->getState().getPtr(), Ex,
1404                                                N->getLocationContext());
1405        }
1406
1407        PathDiagnosticCallPiece *C =
1408          PathDiagnosticCallPiece::construct(N, *CE, SM);
1409        GRBugReporter& BR = PDB.getBugReporter();
1410        BR.addCallPieceLocationContextPair(C, CE->getCalleeContext());
1411
1412        EB.addEdge(C->callReturn, true);
1413        EB.flushLocations();
1414
1415        PD.getActivePath().push_front(C);
1416        PD.pushActivePath(&C->path);
1417        CallStack.push_back(StackDiagPair(C, N));
1418        break;
1419      }
1420
1421      // Pop the call hierarchy if we are done walking the contents
1422      // of a function call.
1423      if (Optional<CallEnter> CE = P.getAs<CallEnter>()) {
1424        // Add an edge to the start of the function.
1425        const Decl *D = CE->getCalleeContext()->getDecl();
1426        PathDiagnosticLocation pos =
1427          PathDiagnosticLocation::createBegin(D, SM);
1428        EB.addEdge(pos);
1429
1430        // Flush all locations, and pop the active path.
1431        bool VisitedEntireCall = PD.isWithinCall();
1432        EB.flushLocations();
1433        PD.popActivePath();
1434        PDB.LC = N->getLocationContext();
1435
1436        // Either we just added a bunch of stuff to the top-level path, or
1437        // we have a previous CallExitEnd.  If the former, it means that the
1438        // path terminated within a function call.  We must then take the
1439        // current contents of the active path and place it within
1440        // a new PathDiagnosticCallPiece.
1441        PathDiagnosticCallPiece *C;
1442        if (VisitedEntireCall) {
1443          C = cast<PathDiagnosticCallPiece>(PD.getActivePath().front());
1444        } else {
1445          const Decl *Caller = CE->getLocationContext()->getDecl();
1446          C = PathDiagnosticCallPiece::construct(PD.getActivePath(), Caller);
1447          GRBugReporter& BR = PDB.getBugReporter();
1448          BR.addCallPieceLocationContextPair(C, CE->getCalleeContext());
1449        }
1450
1451        C->setCallee(*CE, SM);
1452        EB.addContext(C->getLocation());
1453
1454        if (!CallStack.empty()) {
1455          assert(CallStack.back().first == C);
1456          CallStack.pop_back();
1457        }
1458        break;
1459      }
1460
1461      // Note that is important that we update the LocationContext
1462      // after looking at CallExits.  CallExit basically adds an
1463      // edge in the *caller*, so we don't want to update the LocationContext
1464      // too soon.
1465      PDB.LC = N->getLocationContext();
1466
1467      // Block edges.
1468      if (Optional<BlockEdge> BE = P.getAs<BlockEdge>()) {
1469        // Does this represent entering a call?  If so, look at propagating
1470        // interesting symbols across call boundaries.
1471        if (NextNode) {
1472          const LocationContext *CallerCtx = NextNode->getLocationContext();
1473          const LocationContext *CalleeCtx = PDB.LC;
1474          if (CallerCtx != CalleeCtx) {
1475            reversePropagateInterestingSymbols(*PDB.getBugReport(), IE,
1476                                               N->getState().getPtr(),
1477                                               CalleeCtx, CallerCtx);
1478          }
1479        }
1480
1481        // Are we jumping to the head of a loop?  Add a special diagnostic.
1482        if (const Stmt *Loop = BE->getSrc()->getLoopTarget()) {
1483          PathDiagnosticLocation L(Loop, SM, PDB.LC);
1484          const CompoundStmt *CS = NULL;
1485
1486          if (const ForStmt *FS = dyn_cast<ForStmt>(Loop))
1487            CS = dyn_cast<CompoundStmt>(FS->getBody());
1488          else if (const WhileStmt *WS = dyn_cast<WhileStmt>(Loop))
1489            CS = dyn_cast<CompoundStmt>(WS->getBody());
1490
1491          PathDiagnosticEventPiece *p =
1492            new PathDiagnosticEventPiece(L,
1493                                        "Looping back to the head of the loop");
1494          p->setPrunable(true);
1495
1496          EB.addEdge(p->getLocation(), true);
1497          PD.getActivePath().push_front(p);
1498
1499          if (CS) {
1500            PathDiagnosticLocation BL =
1501              PathDiagnosticLocation::createEndBrace(CS, SM);
1502            EB.addEdge(BL);
1503          }
1504        }
1505
1506        const CFGBlock *BSrc = BE->getSrc();
1507        ParentMap &PM = PDB.getParentMap();
1508
1509        if (const Stmt *Term = BSrc->getTerminator()) {
1510          // Are we jumping past the loop body without ever executing the
1511          // loop (because the condition was false)?
1512          if (isLoopJumpPastBody(Term, &*BE) &&
1513              !isInLoopBody(PM,
1514                            getStmtBeforeCond(PM,
1515                                              BSrc->getTerminatorCondition(),
1516                                              N),
1517                            Term)) {
1518            PathDiagnosticLocation L(Term, SM, PDB.LC);
1519            PathDiagnosticEventPiece *PE =
1520                new PathDiagnosticEventPiece(L, "Loop body executed 0 times");
1521            PE->setPrunable(true);
1522
1523            EB.addEdge(PE->getLocation(), true);
1524            PD.getActivePath().push_front(PE);
1525          }
1526
1527          // In any case, add the terminator as the current statement
1528          // context for control edges.
1529          EB.addContext(Term);
1530        }
1531
1532        break;
1533      }
1534
1535      if (Optional<BlockEntrance> BE = P.getAs<BlockEntrance>()) {
1536        Optional<CFGElement> First = BE->getFirstElement();
1537        if (Optional<CFGStmt> S = First ? First->getAs<CFGStmt>() : None) {
1538          const Stmt *stmt = S->getStmt();
1539          if (IsControlFlowExpr(stmt)) {
1540            // Add the proper context for '&&', '||', and '?'.
1541            EB.addContext(stmt);
1542          }
1543          else
1544            EB.addExtendedContext(PDB.getEnclosingStmtLocation(stmt).asStmt());
1545        }
1546
1547        break;
1548      }
1549
1550
1551    } while (0);
1552
1553    if (!NextNode)
1554      continue;
1555
1556    // Add pieces from custom visitors.
1557    BugReport *R = PDB.getBugReport();
1558    for (ArrayRef<BugReporterVisitor *>::iterator I = visitors.begin(),
1559                                                  E = visitors.end();
1560         I != E; ++I) {
1561      if (PathDiagnosticPiece *p = (*I)->VisitNode(N, NextNode, PDB, *R)) {
1562        const PathDiagnosticLocation &Loc = p->getLocation();
1563        EB.addEdge(Loc, true);
1564        PD.getActivePath().push_front(p);
1565        updateStackPiecesWithMessage(p, CallStack);
1566
1567        if (const Stmt *S = Loc.asStmt())
1568          EB.addExtendedContext(PDB.getEnclosingStmtLocation(S).asStmt());
1569      }
1570    }
1571  }
1572
1573  return PDB.getBugReport()->isValid();
1574}
1575
1576//===----------------------------------------------------------------------===//
1577// Methods for BugType and subclasses.
1578//===----------------------------------------------------------------------===//
1579BugType::~BugType() { }
1580
1581void BugType::FlushReports(BugReporter &BR) {}
1582
1583void BuiltinBug::anchor() {}
1584
1585//===----------------------------------------------------------------------===//
1586// Methods for BugReport and subclasses.
1587//===----------------------------------------------------------------------===//
1588
1589void BugReport::NodeResolver::anchor() {}
1590
1591void BugReport::addVisitor(BugReporterVisitor* visitor) {
1592  if (!visitor)
1593    return;
1594
1595  llvm::FoldingSetNodeID ID;
1596  visitor->Profile(ID);
1597  void *InsertPos;
1598
1599  if (CallbacksSet.FindNodeOrInsertPos(ID, InsertPos)) {
1600    delete visitor;
1601    return;
1602  }
1603
1604  CallbacksSet.InsertNode(visitor, InsertPos);
1605  Callbacks.push_back(visitor);
1606  ++ConfigurationChangeToken;
1607}
1608
1609BugReport::~BugReport() {
1610  for (visitor_iterator I = visitor_begin(), E = visitor_end(); I != E; ++I) {
1611    delete *I;
1612  }
1613  while (!interestingSymbols.empty()) {
1614    popInterestingSymbolsAndRegions();
1615  }
1616}
1617
1618const Decl *BugReport::getDeclWithIssue() const {
1619  if (DeclWithIssue)
1620    return DeclWithIssue;
1621
1622  const ExplodedNode *N = getErrorNode();
1623  if (!N)
1624    return 0;
1625
1626  const LocationContext *LC = N->getLocationContext();
1627  return LC->getCurrentStackFrame()->getDecl();
1628}
1629
1630void BugReport::Profile(llvm::FoldingSetNodeID& hash) const {
1631  hash.AddPointer(&BT);
1632  hash.AddString(Description);
1633  PathDiagnosticLocation UL = getUniqueingLocation();
1634  if (UL.isValid()) {
1635    UL.Profile(hash);
1636  } else if (Location.isValid()) {
1637    Location.Profile(hash);
1638  } else {
1639    assert(ErrorNode);
1640    hash.AddPointer(GetCurrentOrPreviousStmt(ErrorNode));
1641  }
1642
1643  for (SmallVectorImpl<SourceRange>::const_iterator I =
1644      Ranges.begin(), E = Ranges.end(); I != E; ++I) {
1645    const SourceRange range = *I;
1646    if (!range.isValid())
1647      continue;
1648    hash.AddInteger(range.getBegin().getRawEncoding());
1649    hash.AddInteger(range.getEnd().getRawEncoding());
1650  }
1651}
1652
1653void BugReport::markInteresting(SymbolRef sym) {
1654  if (!sym)
1655    return;
1656
1657  // If the symbol wasn't already in our set, note a configuration change.
1658  if (getInterestingSymbols().insert(sym).second)
1659    ++ConfigurationChangeToken;
1660
1661  if (const SymbolMetadata *meta = dyn_cast<SymbolMetadata>(sym))
1662    getInterestingRegions().insert(meta->getRegion());
1663}
1664
1665void BugReport::markInteresting(const MemRegion *R) {
1666  if (!R)
1667    return;
1668
1669  // If the base region wasn't already in our set, note a configuration change.
1670  R = R->getBaseRegion();
1671  if (getInterestingRegions().insert(R).second)
1672    ++ConfigurationChangeToken;
1673
1674  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R))
1675    getInterestingSymbols().insert(SR->getSymbol());
1676}
1677
1678void BugReport::markInteresting(SVal V) {
1679  markInteresting(V.getAsRegion());
1680  markInteresting(V.getAsSymbol());
1681}
1682
1683void BugReport::markInteresting(const LocationContext *LC) {
1684  if (!LC)
1685    return;
1686  InterestingLocationContexts.insert(LC);
1687}
1688
1689bool BugReport::isInteresting(SVal V) {
1690  return isInteresting(V.getAsRegion()) || isInteresting(V.getAsSymbol());
1691}
1692
1693bool BugReport::isInteresting(SymbolRef sym) {
1694  if (!sym)
1695    return false;
1696  // We don't currently consider metadata symbols to be interesting
1697  // even if we know their region is interesting. Is that correct behavior?
1698  return getInterestingSymbols().count(sym);
1699}
1700
1701bool BugReport::isInteresting(const MemRegion *R) {
1702  if (!R)
1703    return false;
1704  R = R->getBaseRegion();
1705  bool b = getInterestingRegions().count(R);
1706  if (b)
1707    return true;
1708  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R))
1709    return getInterestingSymbols().count(SR->getSymbol());
1710  return false;
1711}
1712
1713bool BugReport::isInteresting(const LocationContext *LC) {
1714  if (!LC)
1715    return false;
1716  return InterestingLocationContexts.count(LC);
1717}
1718
1719void BugReport::lazyInitializeInterestingSets() {
1720  if (interestingSymbols.empty()) {
1721    interestingSymbols.push_back(new Symbols());
1722    interestingRegions.push_back(new Regions());
1723  }
1724}
1725
1726BugReport::Symbols &BugReport::getInterestingSymbols() {
1727  lazyInitializeInterestingSets();
1728  return *interestingSymbols.back();
1729}
1730
1731BugReport::Regions &BugReport::getInterestingRegions() {
1732  lazyInitializeInterestingSets();
1733  return *interestingRegions.back();
1734}
1735
1736void BugReport::pushInterestingSymbolsAndRegions() {
1737  interestingSymbols.push_back(new Symbols(getInterestingSymbols()));
1738  interestingRegions.push_back(new Regions(getInterestingRegions()));
1739}
1740
1741void BugReport::popInterestingSymbolsAndRegions() {
1742  delete interestingSymbols.back();
1743  interestingSymbols.pop_back();
1744  delete interestingRegions.back();
1745  interestingRegions.pop_back();
1746}
1747
1748const Stmt *BugReport::getStmt() const {
1749  if (!ErrorNode)
1750    return 0;
1751
1752  ProgramPoint ProgP = ErrorNode->getLocation();
1753  const Stmt *S = NULL;
1754
1755  if (Optional<BlockEntrance> BE = ProgP.getAs<BlockEntrance>()) {
1756    CFGBlock &Exit = ProgP.getLocationContext()->getCFG()->getExit();
1757    if (BE->getBlock() == &Exit)
1758      S = GetPreviousStmt(ErrorNode);
1759  }
1760  if (!S)
1761    S = GetStmt(ProgP);
1762
1763  return S;
1764}
1765
1766std::pair<BugReport::ranges_iterator, BugReport::ranges_iterator>
1767BugReport::getRanges() {
1768    // If no custom ranges, add the range of the statement corresponding to
1769    // the error node.
1770    if (Ranges.empty()) {
1771      if (const Expr *E = dyn_cast_or_null<Expr>(getStmt()))
1772        addRange(E->getSourceRange());
1773      else
1774        return std::make_pair(ranges_iterator(), ranges_iterator());
1775    }
1776
1777    // User-specified absence of range info.
1778    if (Ranges.size() == 1 && !Ranges.begin()->isValid())
1779      return std::make_pair(ranges_iterator(), ranges_iterator());
1780
1781    return std::make_pair(Ranges.begin(), Ranges.end());
1782}
1783
1784PathDiagnosticLocation BugReport::getLocation(const SourceManager &SM) const {
1785  if (ErrorNode) {
1786    assert(!Location.isValid() &&
1787     "Either Location or ErrorNode should be specified but not both.");
1788
1789    if (const Stmt *S = GetCurrentOrPreviousStmt(ErrorNode)) {
1790      const LocationContext *LC = ErrorNode->getLocationContext();
1791
1792      // For member expressions, return the location of the '.' or '->'.
1793      if (const MemberExpr *ME = dyn_cast<MemberExpr>(S))
1794        return PathDiagnosticLocation::createMemberLoc(ME, SM);
1795      // For binary operators, return the location of the operator.
1796      if (const BinaryOperator *B = dyn_cast<BinaryOperator>(S))
1797        return PathDiagnosticLocation::createOperatorLoc(B, SM);
1798
1799      if (ErrorNode->getLocation().getAs<PostStmtPurgeDeadSymbols>())
1800        return PathDiagnosticLocation::createEnd(S, SM, LC);
1801
1802      return PathDiagnosticLocation::createBegin(S, SM, LC);
1803    }
1804  } else {
1805    assert(Location.isValid());
1806    return Location;
1807  }
1808
1809  return PathDiagnosticLocation();
1810}
1811
1812//===----------------------------------------------------------------------===//
1813// Methods for BugReporter and subclasses.
1814//===----------------------------------------------------------------------===//
1815
1816BugReportEquivClass::~BugReportEquivClass() { }
1817GRBugReporter::~GRBugReporter() { }
1818BugReporterData::~BugReporterData() {}
1819
1820ExplodedGraph &GRBugReporter::getGraph() { return Eng.getGraph(); }
1821
1822ProgramStateManager&
1823GRBugReporter::getStateManager() { return Eng.getStateManager(); }
1824
1825BugReporter::~BugReporter() {
1826  FlushReports();
1827
1828  // Free the bug reports we are tracking.
1829  typedef std::vector<BugReportEquivClass *> ContTy;
1830  for (ContTy::iterator I = EQClassesVector.begin(), E = EQClassesVector.end();
1831       I != E; ++I) {
1832    delete *I;
1833  }
1834}
1835
1836void BugReporter::FlushReports() {
1837  if (BugTypes.isEmpty())
1838    return;
1839
1840  // First flush the warnings for each BugType.  This may end up creating new
1841  // warnings and new BugTypes.
1842  // FIXME: Only NSErrorChecker needs BugType's FlushReports.
1843  // Turn NSErrorChecker into a proper checker and remove this.
1844  SmallVector<const BugType*, 16> bugTypes;
1845  for (BugTypesTy::iterator I=BugTypes.begin(), E=BugTypes.end(); I!=E; ++I)
1846    bugTypes.push_back(*I);
1847  for (SmallVector<const BugType*, 16>::iterator
1848         I = bugTypes.begin(), E = bugTypes.end(); I != E; ++I)
1849    const_cast<BugType*>(*I)->FlushReports(*this);
1850
1851  // We need to flush reports in deterministic order to ensure the order
1852  // of the reports is consistent between runs.
1853  typedef std::vector<BugReportEquivClass *> ContVecTy;
1854  for (ContVecTy::iterator EI=EQClassesVector.begin(), EE=EQClassesVector.end();
1855       EI != EE; ++EI){
1856    BugReportEquivClass& EQ = **EI;
1857    FlushReport(EQ);
1858  }
1859
1860  // BugReporter owns and deletes only BugTypes created implicitly through
1861  // EmitBasicReport.
1862  // FIXME: There are leaks from checkers that assume that the BugTypes they
1863  // create will be destroyed by the BugReporter.
1864  for (llvm::StringMap<BugType*>::iterator
1865         I = StrBugTypes.begin(), E = StrBugTypes.end(); I != E; ++I)
1866    delete I->second;
1867
1868  // Remove all references to the BugType objects.
1869  BugTypes = F.getEmptySet();
1870}
1871
1872//===----------------------------------------------------------------------===//
1873// PathDiagnostics generation.
1874//===----------------------------------------------------------------------===//
1875
1876namespace {
1877/// A wrapper around a report graph, which contains only a single path, and its
1878/// node maps.
1879class ReportGraph {
1880public:
1881  OwningPtr<ExplodedGraph> Graph;
1882  InterExplodedGraphMap BackMap;
1883  ExplodedNode *ErrorNode;
1884  size_t Index;
1885};
1886
1887/// A wrapper around a trimmed graph and its node maps.
1888class TrimmedGraph {
1889  InterExplodedGraphMap ForwardMap;
1890  InterExplodedGraphMap InverseMap;
1891
1892  typedef llvm::DenseMap<const ExplodedNode *, unsigned> PriorityMapTy;
1893  PriorityMapTy PriorityMap;
1894
1895  OwningPtr<ExplodedGraph> G;
1896  const ExplodedNode *Root;
1897public:
1898  TrimmedGraph(const ExplodedGraph *OriginalGraph,
1899               ArrayRef<const ExplodedNode *> Nodes);
1900
1901  void createBestReportGraph(ArrayRef<const ExplodedNode *> Nodes,
1902                             ReportGraph &GraphWrapper) const;
1903
1904  void removeErrorNode(const ExplodedNode *Node);
1905};
1906
1907}
1908
1909TrimmedGraph::TrimmedGraph(const ExplodedGraph *OriginalGraph,
1910                           ArrayRef<const ExplodedNode *> Nodes) {
1911  // The trimmed graph is created in the body of the constructor to ensure
1912  // that the DenseMaps have been initialized already.
1913  G.reset(OriginalGraph->trim(Nodes, /*BreakCycles=*/true,
1914                              &ForwardMap, &InverseMap));
1915
1916  // Find the (first) error node in the trimmed graph.  We just need to consult
1917  // the node map which maps from nodes in the original graph to nodes
1918  // in the new graph.
1919  std::queue<std::pair<const ExplodedNode *, unsigned> > WS;
1920  typedef llvm::SmallDenseMap<const ExplodedNode *, size_t, 32> IndexMapTy;
1921  IndexMapTy IndexMap(llvm::NextPowerOf2(Nodes.size() + 1));
1922
1923  for (unsigned i = 0, count = Nodes.size(); i < count; ++i) {
1924    const ExplodedNode *OriginalNode = Nodes[i];
1925    if (const ExplodedNode *N = ForwardMap.lookup(OriginalNode)) {
1926      WS.push(std::make_pair(N, 0));
1927      IndexMap[OriginalNode] = i;
1928    }
1929  }
1930
1931  assert(!WS.empty() && "No error node found in the trimmed graph.");
1932
1933  // Perform a reverse BFS to find all the shortest paths.
1934  Root = 0;
1935  while (!WS.empty()) {
1936    const ExplodedNode *Node;
1937    unsigned Priority;
1938    llvm::tie(Node, Priority) = WS.front();
1939    WS.pop();
1940
1941    PriorityMapTy::iterator PriorityEntry;
1942    bool IsNew;
1943    llvm::tie(PriorityEntry, IsNew) =
1944      PriorityMap.insert(std::make_pair(Node, Priority));
1945
1946    if (!IsNew) {
1947      assert(PriorityEntry->second <= Priority);
1948      continue;
1949    }
1950
1951    if (Node->pred_empty()) {
1952      assert(!Root && "more than one root");
1953      Root = Node;
1954    }
1955
1956    for (ExplodedNode::const_pred_iterator I = Node->pred_begin(),
1957                                           E = Node->pred_end();
1958         I != E; ++I)
1959      WS.push(std::make_pair(*I, Priority + 1));
1960  }
1961
1962  assert(Root);
1963}
1964
1965void TrimmedGraph::createBestReportGraph(ArrayRef<const ExplodedNode *> Nodes,
1966                                         ReportGraph &GraphWrapper) const {
1967  assert(!GraphWrapper.Graph && "ReportGraph is already in use");
1968  assert(GraphWrapper.BackMap.empty() && "ReportGraph is already in use");
1969
1970  // Find the (first) error node in the trimmed graph.  We just need to consult
1971  // the node map which maps from nodes in the original graph to nodes
1972  // in the new graph.
1973  std::queue<std::pair<const ExplodedNode *, unsigned> > WS;
1974  typedef llvm::SmallDenseMap<const ExplodedNode *, size_t, 32> IndexMapTy;
1975  IndexMapTy IndexMap(llvm::NextPowerOf2(Nodes.size() + 1));
1976
1977  for (unsigned i = 0, count = Nodes.size(); i < count; ++i) {
1978    const ExplodedNode *OriginalNode = Nodes[i];
1979    if (const ExplodedNode *N = ForwardMap.lookup(OriginalNode)) {
1980      WS.push(std::make_pair(N, 0));
1981      IndexMap[OriginalNode] = i;
1982    }
1983  }
1984
1985  assert(!WS.empty() && "No error node found in the trimmed graph.");
1986
1987  // Create a new graph with a single path.  This is the graph
1988  // that will be returned to the caller.
1989  ExplodedGraph *GNew = new ExplodedGraph();
1990  GraphWrapper.Graph.reset(GNew);
1991
1992  // Now walk from the root down the BFS path, always taking the successor
1993  // with the lowest number.
1994  ExplodedNode *Last = 0;
1995  for ( const ExplodedNode *N = Root ;;) {
1996    // Lookup the number associated with the current node.
1997    PriorityMapTy::const_iterator I = PriorityMap.find(N);
1998    assert(I != PriorityMap.end());
1999
2000    // Create the equivalent node in the new graph with the same state
2001    // and location.
2002    ExplodedNode *NewN = GNew->getNode(N->getLocation(), N->getState());
2003
2004    // Store the mapping to the original node.
2005    InterExplodedGraphMap::const_iterator IMitr = InverseMap.find(N);
2006    assert(IMitr != InverseMap.end() && "No mapping to original node.");
2007    GraphWrapper.BackMap[NewN] = IMitr->second;
2008
2009    // Link up the new node with the previous node.
2010    if (Last)
2011      NewN->addPredecessor(Last, *GNew);
2012
2013    Last = NewN;
2014
2015    // Are we at the final node?
2016    IndexMapTy::iterator IMI = IndexMap.find(IMitr->second);
2017    if (IMI != IndexMap.end()) {
2018      GraphWrapper.ErrorNode = NewN;
2019      GraphWrapper.Index = IMI->second;
2020      break;
2021    }
2022
2023    // Find the next successor node.  We choose the node that is marked
2024    // with the lowest BFS number.
2025    unsigned MinVal = -1U;
2026    for (ExplodedNode::const_succ_iterator SI = N->succ_begin(),
2027                                           SE = N->succ_end();
2028         SI != SE; ++SI) {
2029      I = PriorityMap.find(*SI);
2030
2031      if (I == PriorityMap.end())
2032        continue;
2033
2034      if (I->second < MinVal) {
2035        N = *SI;
2036        MinVal = I->second;
2037      }
2038    }
2039
2040    assert(MinVal != -1U);
2041  }
2042}
2043
2044void TrimmedGraph::removeErrorNode(const ExplodedNode *ErrorNode) {
2045  ErrorNode = ForwardMap[ErrorNode];
2046  assert(ErrorNode && "not an error node");
2047
2048  PriorityMapTy::iterator PriorityEntry = PriorityMap.find(ErrorNode);
2049  assert(PriorityEntry != PriorityMap.end() && "error node already removed");
2050  PriorityMap.erase(PriorityEntry);
2051
2052  std::queue<const ExplodedNode *> WS;
2053  for (ExplodedNode::const_pred_iterator PI = ErrorNode->pred_begin(),
2054                                         PE = ErrorNode->pred_end();
2055       PI != PE; ++PI) {
2056    assert(PriorityMap.find(*PI) != PriorityMap.end() && "predecessor removed");
2057    WS.push(*PI);
2058  }
2059
2060  // Update all nodes possibly affected by this change.
2061  while (!WS.empty()) {
2062    const ExplodedNode *N = WS.front();
2063    WS.pop();
2064
2065    PriorityEntry = PriorityMap.find(N);
2066
2067    // Did we process this node already and find it unreachable?
2068    if (PriorityEntry == PriorityMap.end())
2069      continue;
2070
2071    unsigned MinPriority = -1U;
2072    for (ExplodedNode::const_succ_iterator SI = N->succ_begin(),
2073                                           SE = N->succ_end();
2074         SI != SE; ++SI) {
2075      PriorityMapTy::iterator SuccEntry = PriorityMap.find(*SI);
2076      if (SuccEntry == PriorityMap.end())
2077        continue;
2078      MinPriority = std::min(SuccEntry->second, MinPriority);
2079    }
2080
2081    if (MinPriority == -1U)
2082      PriorityMap.erase(N);
2083    else if (PriorityMap[N] == MinPriority + 1)
2084      continue;
2085    else
2086      PriorityMap[N] = MinPriority + 1;
2087
2088    for (ExplodedNode::const_pred_iterator PI = N->pred_begin(),
2089                                           PE = N->pred_end();
2090         PI != PE; ++PI) {
2091      assert(PriorityMap.find(*PI) != PriorityMap.end() && "premature removal");
2092      WS.push(*PI);
2093    }
2094  }
2095}
2096
2097
2098/// CompactPathDiagnostic - This function postprocesses a PathDiagnostic object
2099///  and collapses PathDiagosticPieces that are expanded by macros.
2100static void CompactPathDiagnostic(PathPieces &path, const SourceManager& SM) {
2101  typedef std::vector<std::pair<IntrusiveRefCntPtr<PathDiagnosticMacroPiece>,
2102                                SourceLocation> > MacroStackTy;
2103
2104  typedef std::vector<IntrusiveRefCntPtr<PathDiagnosticPiece> >
2105          PiecesTy;
2106
2107  MacroStackTy MacroStack;
2108  PiecesTy Pieces;
2109
2110  for (PathPieces::const_iterator I = path.begin(), E = path.end();
2111       I!=E; ++I) {
2112
2113    PathDiagnosticPiece *piece = I->getPtr();
2114
2115    // Recursively compact calls.
2116    if (PathDiagnosticCallPiece *call=dyn_cast<PathDiagnosticCallPiece>(piece)){
2117      CompactPathDiagnostic(call->path, SM);
2118    }
2119
2120    // Get the location of the PathDiagnosticPiece.
2121    const FullSourceLoc Loc = piece->getLocation().asLocation();
2122
2123    // Determine the instantiation location, which is the location we group
2124    // related PathDiagnosticPieces.
2125    SourceLocation InstantiationLoc = Loc.isMacroID() ?
2126                                      SM.getExpansionLoc(Loc) :
2127                                      SourceLocation();
2128
2129    if (Loc.isFileID()) {
2130      MacroStack.clear();
2131      Pieces.push_back(piece);
2132      continue;
2133    }
2134
2135    assert(Loc.isMacroID());
2136
2137    // Is the PathDiagnosticPiece within the same macro group?
2138    if (!MacroStack.empty() && InstantiationLoc == MacroStack.back().second) {
2139      MacroStack.back().first->subPieces.push_back(piece);
2140      continue;
2141    }
2142
2143    // We aren't in the same group.  Are we descending into a new macro
2144    // or are part of an old one?
2145    IntrusiveRefCntPtr<PathDiagnosticMacroPiece> MacroGroup;
2146
2147    SourceLocation ParentInstantiationLoc = InstantiationLoc.isMacroID() ?
2148                                          SM.getExpansionLoc(Loc) :
2149                                          SourceLocation();
2150
2151    // Walk the entire macro stack.
2152    while (!MacroStack.empty()) {
2153      if (InstantiationLoc == MacroStack.back().second) {
2154        MacroGroup = MacroStack.back().first;
2155        break;
2156      }
2157
2158      if (ParentInstantiationLoc == MacroStack.back().second) {
2159        MacroGroup = MacroStack.back().first;
2160        break;
2161      }
2162
2163      MacroStack.pop_back();
2164    }
2165
2166    if (!MacroGroup || ParentInstantiationLoc == MacroStack.back().second) {
2167      // Create a new macro group and add it to the stack.
2168      PathDiagnosticMacroPiece *NewGroup =
2169        new PathDiagnosticMacroPiece(
2170          PathDiagnosticLocation::createSingleLocation(piece->getLocation()));
2171
2172      if (MacroGroup)
2173        MacroGroup->subPieces.push_back(NewGroup);
2174      else {
2175        assert(InstantiationLoc.isFileID());
2176        Pieces.push_back(NewGroup);
2177      }
2178
2179      MacroGroup = NewGroup;
2180      MacroStack.push_back(std::make_pair(MacroGroup, InstantiationLoc));
2181    }
2182
2183    // Finally, add the PathDiagnosticPiece to the group.
2184    MacroGroup->subPieces.push_back(piece);
2185  }
2186
2187  // Now take the pieces and construct a new PathDiagnostic.
2188  path.clear();
2189
2190  for (PiecesTy::iterator I=Pieces.begin(), E=Pieces.end(); I!=E; ++I)
2191    path.push_back(*I);
2192}
2193
2194bool GRBugReporter::generatePathDiagnostic(PathDiagnostic& PD,
2195                                           PathDiagnosticConsumer &PC,
2196                                           ArrayRef<BugReport *> &bugReports) {
2197  assert(!bugReports.empty());
2198
2199  bool HasValid = false;
2200  SmallVector<const ExplodedNode *, 32> errorNodes;
2201  for (ArrayRef<BugReport*>::iterator I = bugReports.begin(),
2202                                      E = bugReports.end(); I != E; ++I) {
2203    if ((*I)->isValid()) {
2204      HasValid = true;
2205      errorNodes.push_back((*I)->getErrorNode());
2206    } else {
2207      errorNodes.push_back(0);
2208    }
2209  }
2210
2211  // If all the reports have been marked invalid by a previous path generation,
2212  // we're done.
2213  if (!HasValid)
2214    return false;
2215
2216  typedef PathDiagnosticConsumer::PathGenerationScheme PathGenerationScheme;
2217  PathGenerationScheme ActiveScheme = PC.getGenerationScheme();
2218
2219  TrimmedGraph TrimG(&getGraph(), errorNodes);
2220
2221  for (size_t Remaining = bugReports.size(); Remaining > 0; --Remaining) {
2222    // Construct a new graph that contains only a single path from the error
2223    // node to a root.
2224    ReportGraph ErrorGraph;
2225    TrimG.createBestReportGraph(errorNodes, ErrorGraph);
2226
2227    // Find the BugReport with the original location.
2228    assert(ErrorGraph.Index < bugReports.size());
2229    BugReport *R = bugReports[ErrorGraph.Index];
2230    assert(R && "No original report found for sliced graph.");
2231    assert(R->isValid() && "Report selected by trimmed graph marked invalid.");
2232
2233    // Don't try to reuse this report if it ends up being suppressed.
2234    errorNodes[ErrorGraph.Index] = 0;
2235
2236    // Start building the path diagnostic...
2237    PathDiagnosticBuilder PDB(*this, R, ErrorGraph.BackMap, &PC);
2238    const ExplodedNode *N = ErrorGraph.ErrorNode;
2239
2240    // Register additional node visitors.
2241    R->addVisitor(new NilReceiverBRVisitor());
2242    R->addVisitor(new ConditionBRVisitor());
2243    R->addVisitor(new LikelyFalsePositiveSuppressionBRVisitor());
2244
2245    BugReport::VisitorList visitors;
2246    unsigned origReportConfigToken, finalReportConfigToken;
2247
2248    // While generating diagnostics, it's possible the visitors will decide
2249    // new symbols and regions are interesting, or add other visitors based on
2250    // the information they find. If they do, we need to regenerate the path
2251    // based on our new report configuration.
2252    do {
2253      // Get a clean copy of all the visitors.
2254      for (BugReport::visitor_iterator I = R->visitor_begin(),
2255                                       E = R->visitor_end(); I != E; ++I)
2256        visitors.push_back((*I)->clone());
2257
2258      // Clear out the active path from any previous work.
2259      PD.resetPath();
2260      origReportConfigToken = R->getConfigurationChangeToken();
2261
2262      // Generate the very last diagnostic piece - the piece is visible before
2263      // the trace is expanded.
2264      PathDiagnosticPiece *LastPiece = 0;
2265      for (BugReport::visitor_iterator I = visitors.begin(), E = visitors.end();
2266          I != E; ++I) {
2267        if (PathDiagnosticPiece *Piece = (*I)->getEndPath(PDB, N, *R)) {
2268          assert (!LastPiece &&
2269              "There can only be one final piece in a diagnostic.");
2270          LastPiece = Piece;
2271        }
2272      }
2273
2274      if (ActiveScheme != PathDiagnosticConsumer::None) {
2275        if (!LastPiece)
2276          LastPiece = BugReporterVisitor::getDefaultEndPath(PDB, N, *R);
2277        assert(LastPiece);
2278        PD.setEndOfPath(LastPiece);
2279      }
2280
2281      switch (ActiveScheme) {
2282      case PathDiagnosticConsumer::Extensive:
2283        GenerateExtensivePathDiagnostic(PD, PDB, N, visitors);
2284        break;
2285      case PathDiagnosticConsumer::Minimal:
2286        GenerateMinimalPathDiagnostic(PD, PDB, N, visitors);
2287        break;
2288      case PathDiagnosticConsumer::None:
2289        GenerateVisitorsOnlyPathDiagnostic(PD, PDB, N, visitors);
2290        break;
2291      }
2292
2293      // Clean up the visitors we used.
2294      llvm::DeleteContainerPointers(visitors);
2295
2296      // Did anything change while generating this path?
2297      finalReportConfigToken = R->getConfigurationChangeToken();
2298    } while (finalReportConfigToken != origReportConfigToken);
2299
2300    if (!R->isValid()) {
2301      TrimG.removeErrorNode(R->getErrorNode());
2302      continue;
2303    }
2304
2305    // Finally, prune the diagnostic path of uninteresting stuff.
2306    if (!PD.path.empty()) {
2307      // Remove messages that are basically the same.
2308      removeRedundantMsgs(PD.getMutablePieces());
2309
2310      if (R->shouldPrunePath() &&
2311          getEngine().getAnalysisManager().options.shouldPrunePaths()) {
2312        bool stillHasNotes = RemoveUnneededCalls(PD.getMutablePieces(), R);
2313        assert(stillHasNotes);
2314        (void)stillHasNotes;
2315      }
2316
2317      adjustCallLocations(PD.getMutablePieces());
2318    }
2319
2320    // We found a report and didn't suppress it.
2321    return true;
2322  }
2323
2324  // We suppressed all the reports in this equivalence class.
2325  return false;
2326}
2327
2328void BugReporter::Register(BugType *BT) {
2329  BugTypes = F.add(BugTypes, BT);
2330}
2331
2332void BugReporter::emitReport(BugReport* R) {
2333  // Compute the bug report's hash to determine its equivalence class.
2334  llvm::FoldingSetNodeID ID;
2335  R->Profile(ID);
2336
2337  // Lookup the equivance class.  If there isn't one, create it.
2338  BugType& BT = R->getBugType();
2339  Register(&BT);
2340  void *InsertPos;
2341  BugReportEquivClass* EQ = EQClasses.FindNodeOrInsertPos(ID, InsertPos);
2342
2343  if (!EQ) {
2344    EQ = new BugReportEquivClass(R);
2345    EQClasses.InsertNode(EQ, InsertPos);
2346    EQClassesVector.push_back(EQ);
2347  }
2348  else
2349    EQ->AddReport(R);
2350}
2351
2352
2353//===----------------------------------------------------------------------===//
2354// Emitting reports in equivalence classes.
2355//===----------------------------------------------------------------------===//
2356
2357namespace {
2358struct FRIEC_WLItem {
2359  const ExplodedNode *N;
2360  ExplodedNode::const_succ_iterator I, E;
2361
2362  FRIEC_WLItem(const ExplodedNode *n)
2363  : N(n), I(N->succ_begin()), E(N->succ_end()) {}
2364};
2365}
2366
2367static BugReport *
2368FindReportInEquivalenceClass(BugReportEquivClass& EQ,
2369                             SmallVectorImpl<BugReport*> &bugReports) {
2370
2371  BugReportEquivClass::iterator I = EQ.begin(), E = EQ.end();
2372  assert(I != E);
2373  BugType& BT = I->getBugType();
2374
2375  // If we don't need to suppress any of the nodes because they are
2376  // post-dominated by a sink, simply add all the nodes in the equivalence class
2377  // to 'Nodes'.  Any of the reports will serve as a "representative" report.
2378  if (!BT.isSuppressOnSink()) {
2379    BugReport *R = I;
2380    for (BugReportEquivClass::iterator I=EQ.begin(), E=EQ.end(); I!=E; ++I) {
2381      const ExplodedNode *N = I->getErrorNode();
2382      if (N) {
2383        R = I;
2384        bugReports.push_back(R);
2385      }
2386    }
2387    return R;
2388  }
2389
2390  // For bug reports that should be suppressed when all paths are post-dominated
2391  // by a sink node, iterate through the reports in the equivalence class
2392  // until we find one that isn't post-dominated (if one exists).  We use a
2393  // DFS traversal of the ExplodedGraph to find a non-sink node.  We could write
2394  // this as a recursive function, but we don't want to risk blowing out the
2395  // stack for very long paths.
2396  BugReport *exampleReport = 0;
2397
2398  for (; I != E; ++I) {
2399    const ExplodedNode *errorNode = I->getErrorNode();
2400
2401    if (!errorNode)
2402      continue;
2403    if (errorNode->isSink()) {
2404      llvm_unreachable(
2405           "BugType::isSuppressSink() should not be 'true' for sink end nodes");
2406    }
2407    // No successors?  By definition this nodes isn't post-dominated by a sink.
2408    if (errorNode->succ_empty()) {
2409      bugReports.push_back(I);
2410      if (!exampleReport)
2411        exampleReport = I;
2412      continue;
2413    }
2414
2415    // At this point we know that 'N' is not a sink and it has at least one
2416    // successor.  Use a DFS worklist to find a non-sink end-of-path node.
2417    typedef FRIEC_WLItem WLItem;
2418    typedef SmallVector<WLItem, 10> DFSWorkList;
2419    llvm::DenseMap<const ExplodedNode *, unsigned> Visited;
2420
2421    DFSWorkList WL;
2422    WL.push_back(errorNode);
2423    Visited[errorNode] = 1;
2424
2425    while (!WL.empty()) {
2426      WLItem &WI = WL.back();
2427      assert(!WI.N->succ_empty());
2428
2429      for (; WI.I != WI.E; ++WI.I) {
2430        const ExplodedNode *Succ = *WI.I;
2431        // End-of-path node?
2432        if (Succ->succ_empty()) {
2433          // If we found an end-of-path node that is not a sink.
2434          if (!Succ->isSink()) {
2435            bugReports.push_back(I);
2436            if (!exampleReport)
2437              exampleReport = I;
2438            WL.clear();
2439            break;
2440          }
2441          // Found a sink?  Continue on to the next successor.
2442          continue;
2443        }
2444        // Mark the successor as visited.  If it hasn't been explored,
2445        // enqueue it to the DFS worklist.
2446        unsigned &mark = Visited[Succ];
2447        if (!mark) {
2448          mark = 1;
2449          WL.push_back(Succ);
2450          break;
2451        }
2452      }
2453
2454      // The worklist may have been cleared at this point.  First
2455      // check if it is empty before checking the last item.
2456      if (!WL.empty() && &WL.back() == &WI)
2457        WL.pop_back();
2458    }
2459  }
2460
2461  // ExampleReport will be NULL if all the nodes in the equivalence class
2462  // were post-dominated by sinks.
2463  return exampleReport;
2464}
2465
2466void BugReporter::FlushReport(BugReportEquivClass& EQ) {
2467  SmallVector<BugReport*, 10> bugReports;
2468  BugReport *exampleReport = FindReportInEquivalenceClass(EQ, bugReports);
2469  if (exampleReport) {
2470    const PathDiagnosticConsumers &C = getPathDiagnosticConsumers();
2471    for (PathDiagnosticConsumers::const_iterator I=C.begin(),
2472                                                 E=C.end(); I != E; ++I) {
2473      FlushReport(exampleReport, **I, bugReports);
2474    }
2475  }
2476}
2477
2478void BugReporter::FlushReport(BugReport *exampleReport,
2479                              PathDiagnosticConsumer &PD,
2480                              ArrayRef<BugReport*> bugReports) {
2481
2482  // FIXME: Make sure we use the 'R' for the path that was actually used.
2483  // Probably doesn't make a difference in practice.
2484  BugType& BT = exampleReport->getBugType();
2485
2486  OwningPtr<PathDiagnostic>
2487    D(new PathDiagnostic(exampleReport->getDeclWithIssue(),
2488                         exampleReport->getBugType().getName(),
2489                         exampleReport->getDescription(),
2490                         exampleReport->getShortDescription(/*Fallback=*/false),
2491                         BT.getCategory(),
2492                         exampleReport->getUniqueingLocation(),
2493                         exampleReport->getUniqueingDecl()));
2494
2495  MaxBugClassSize = std::max(bugReports.size(),
2496                             static_cast<size_t>(MaxBugClassSize));
2497
2498  // Generate the full path diagnostic, using the generation scheme
2499  // specified by the PathDiagnosticConsumer. Note that we have to generate
2500  // path diagnostics even for consumers which do not support paths, because
2501  // the BugReporterVisitors may mark this bug as a false positive.
2502  if (!bugReports.empty())
2503    if (!generatePathDiagnostic(*D.get(), PD, bugReports))
2504      return;
2505
2506  MaxValidBugClassSize = std::max(bugReports.size(),
2507                                  static_cast<size_t>(MaxValidBugClassSize));
2508
2509  // If the path is empty, generate a single step path with the location
2510  // of the issue.
2511  if (D->path.empty()) {
2512    PathDiagnosticLocation L = exampleReport->getLocation(getSourceManager());
2513    PathDiagnosticPiece *piece =
2514      new PathDiagnosticEventPiece(L, exampleReport->getDescription());
2515    BugReport::ranges_iterator Beg, End;
2516    llvm::tie(Beg, End) = exampleReport->getRanges();
2517    for ( ; Beg != End; ++Beg)
2518      piece->addRange(*Beg);
2519    D->setEndOfPath(piece);
2520  }
2521
2522  // Get the meta data.
2523  const BugReport::ExtraTextList &Meta = exampleReport->getExtraText();
2524  for (BugReport::ExtraTextList::const_iterator i = Meta.begin(),
2525                                                e = Meta.end(); i != e; ++i) {
2526    D->addMeta(*i);
2527  }
2528
2529  PD.HandlePathDiagnostic(D.take());
2530}
2531
2532void BugReporter::EmitBasicReport(const Decl *DeclWithIssue,
2533                                  StringRef name,
2534                                  StringRef category,
2535                                  StringRef str, PathDiagnosticLocation Loc,
2536                                  SourceRange* RBeg, unsigned NumRanges) {
2537
2538  // 'BT' is owned by BugReporter.
2539  BugType *BT = getBugTypeForName(name, category);
2540  BugReport *R = new BugReport(*BT, str, Loc);
2541  R->setDeclWithIssue(DeclWithIssue);
2542  for ( ; NumRanges > 0 ; --NumRanges, ++RBeg) R->addRange(*RBeg);
2543  emitReport(R);
2544}
2545
2546BugType *BugReporter::getBugTypeForName(StringRef name,
2547                                        StringRef category) {
2548  SmallString<136> fullDesc;
2549  llvm::raw_svector_ostream(fullDesc) << name << ":" << category;
2550  llvm::StringMapEntry<BugType *> &
2551      entry = StrBugTypes.GetOrCreateValue(fullDesc);
2552  BugType *BT = entry.getValue();
2553  if (!BT) {
2554    BT = new BugType(name, category);
2555    entry.setValue(BT);
2556  }
2557  return BT;
2558}
2559