BugReporter.cpp revision bc0fd8129626ff4e485388311b081e76d0f96795 
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 const Stmt *GetPreviousStmt(const ExplodedNode *N) {
56  for (N = N->getFirstPred(); N; N = N->getFirstPred())
57    if (const Stmt *S = PathDiagnosticLocation::getStmt(N))
58      return S;
59
60  return 0;
61}
62
63static inline const Stmt*
64GetCurrentOrPreviousStmt(const ExplodedNode *N) {
65  if (const Stmt *S = PathDiagnosticLocation::getStmt(N))
66    return S;
67
68  return GetPreviousStmt(N);
69}
70
71//===----------------------------------------------------------------------===//
72// Diagnostic cleanup.
73//===----------------------------------------------------------------------===//
74
75static PathDiagnosticEventPiece *
76eventsDescribeSameCondition(PathDiagnosticEventPiece *X,
77                            PathDiagnosticEventPiece *Y) {
78  // Prefer diagnostics that come from ConditionBRVisitor over
79  // those that came from TrackConstraintBRVisitor.
80  const void *tagPreferred = ConditionBRVisitor::getTag();
81  const void *tagLesser = TrackConstraintBRVisitor::getTag();
82
83  if (X->getLocation() != Y->getLocation())
84    return 0;
85
86  if (X->getTag() == tagPreferred && Y->getTag() == tagLesser)
87    return X;
88
89  if (Y->getTag() == tagPreferred && X->getTag() == tagLesser)
90    return Y;
91
92  return 0;
93}
94
95/// An optimization pass over PathPieces that removes redundant diagnostics
96/// generated by both ConditionBRVisitor and TrackConstraintBRVisitor.  Both
97/// BugReporterVisitors use different methods to generate diagnostics, with
98/// one capable of emitting diagnostics in some cases but not in others.  This
99/// can lead to redundant diagnostic pieces at the same point in a path.
100static void removeRedundantMsgs(PathPieces &path) {
101  unsigned N = path.size();
102  if (N < 2)
103    return;
104  // NOTE: this loop intentionally is not using an iterator.  Instead, we
105  // are streaming the path and modifying it in place.  This is done by
106  // grabbing the front, processing it, and if we decide to keep it append
107  // it to the end of the path.  The entire path is processed in this way.
108  for (unsigned i = 0; i < N; ++i) {
109    IntrusiveRefCntPtr<PathDiagnosticPiece> piece(path.front());
110    path.pop_front();
111
112    switch (piece->getKind()) {
113      case clang::ento::PathDiagnosticPiece::Call:
114        removeRedundantMsgs(cast<PathDiagnosticCallPiece>(piece)->path);
115        break;
116      case clang::ento::PathDiagnosticPiece::Macro:
117        removeRedundantMsgs(cast<PathDiagnosticMacroPiece>(piece)->subPieces);
118        break;
119      case clang::ento::PathDiagnosticPiece::ControlFlow:
120        break;
121      case clang::ento::PathDiagnosticPiece::Event: {
122        if (i == N-1)
123          break;
124
125        if (PathDiagnosticEventPiece *nextEvent =
126            dyn_cast<PathDiagnosticEventPiece>(path.front().getPtr())) {
127          PathDiagnosticEventPiece *event =
128            cast<PathDiagnosticEventPiece>(piece);
129          // Check to see if we should keep one of the two pieces.  If we
130          // come up with a preference, record which piece to keep, and consume
131          // another piece from the path.
132          if (PathDiagnosticEventPiece *pieceToKeep =
133              eventsDescribeSameCondition(event, nextEvent)) {
134            piece = pieceToKeep;
135            path.pop_front();
136            ++i;
137          }
138        }
139        break;
140      }
141    }
142    path.push_back(piece);
143  }
144}
145
146/// A map from PathDiagnosticPiece to the LocationContext of the inlined
147/// function call it represents.
148typedef llvm::DenseMap<const PathPieces *, const LocationContext *>
149        LocationContextMap;
150
151/// Recursively scan through a path and prune out calls and macros pieces
152/// that aren't needed.  Return true if afterwards the path contains
153/// "interesting stuff" which means it shouldn't be pruned from the parent path.
154static bool removeUnneededCalls(PathPieces &pieces, BugReport *R,
155                                LocationContextMap &LCM) {
156  bool containsSomethingInteresting = false;
157  const unsigned N = pieces.size();
158
159  for (unsigned i = 0 ; i < N ; ++i) {
160    // Remove the front piece from the path.  If it is still something we
161    // want to keep once we are done, we will push it back on the end.
162    IntrusiveRefCntPtr<PathDiagnosticPiece> piece(pieces.front());
163    pieces.pop_front();
164
165    // Throw away pieces with invalid locations. Note that we can't throw away
166    // calls just yet because they might have something interesting inside them.
167    // If so, their locations will be adjusted as necessary later.
168    if (piece->getKind() != PathDiagnosticPiece::Call &&
169        piece->getLocation().asLocation().isInvalid())
170      continue;
171
172    switch (piece->getKind()) {
173      case PathDiagnosticPiece::Call: {
174        PathDiagnosticCallPiece *call = cast<PathDiagnosticCallPiece>(piece);
175        // Check if the location context is interesting.
176        assert(LCM.count(&call->path));
177        if (R->isInteresting(LCM[&call->path])) {
178          containsSomethingInteresting = true;
179          break;
180        }
181
182        if (!removeUnneededCalls(call->path, R, LCM))
183          continue;
184
185        containsSomethingInteresting = true;
186        break;
187      }
188      case PathDiagnosticPiece::Macro: {
189        PathDiagnosticMacroPiece *macro = cast<PathDiagnosticMacroPiece>(piece);
190        if (!removeUnneededCalls(macro->subPieces, R, LCM))
191          continue;
192        containsSomethingInteresting = true;
193        break;
194      }
195      case PathDiagnosticPiece::Event: {
196        PathDiagnosticEventPiece *event = cast<PathDiagnosticEventPiece>(piece);
197
198        // We never throw away an event, but we do throw it away wholesale
199        // as part of a path if we throw the entire path away.
200        containsSomethingInteresting |= !event->isPrunable();
201        break;
202      }
203      case PathDiagnosticPiece::ControlFlow:
204        break;
205    }
206
207    pieces.push_back(piece);
208  }
209
210  return containsSomethingInteresting;
211}
212
213/// Recursively scan through a path and make sure that all call pieces have
214/// valid locations. Note that all other pieces with invalid locations should
215/// have already been pruned out.
216static void adjustCallLocations(PathPieces &Pieces,
217                                PathDiagnosticLocation *LastCallLocation = 0) {
218  for (PathPieces::iterator I = Pieces.begin(), E = Pieces.end(); I != E; ++I) {
219    PathDiagnosticCallPiece *Call = dyn_cast<PathDiagnosticCallPiece>(*I);
220
221    if (!Call) {
222      assert((*I)->getLocation().asLocation().isValid());
223      continue;
224    }
225
226    if (LastCallLocation) {
227      if (!Call->callEnter.asLocation().isValid() ||
228          Call->getCaller()->isImplicit())
229        Call->callEnter = *LastCallLocation;
230      if (!Call->callReturn.asLocation().isValid() ||
231          Call->getCaller()->isImplicit())
232        Call->callReturn = *LastCallLocation;
233    }
234
235    // Recursively clean out the subclass.  Keep this call around if
236    // it contains any informative diagnostics.
237    PathDiagnosticLocation *ThisCallLocation;
238    if (Call->callEnterWithin.asLocation().isValid() &&
239        !Call->getCallee()->isImplicit())
240      ThisCallLocation = &Call->callEnterWithin;
241    else
242      ThisCallLocation = &Call->callEnter;
243
244    assert(ThisCallLocation && "Outermost call has an invalid location");
245    adjustCallLocations(Call->path, ThisCallLocation);
246  }
247}
248
249//===----------------------------------------------------------------------===//
250// PathDiagnosticBuilder and its associated routines and helper objects.
251//===----------------------------------------------------------------------===//
252
253namespace {
254class NodeMapClosure : public BugReport::NodeResolver {
255  InterExplodedGraphMap &M;
256public:
257  NodeMapClosure(InterExplodedGraphMap &m) : M(m) {}
258
259  const ExplodedNode *getOriginalNode(const ExplodedNode *N) {
260    return M.lookup(N);
261  }
262};
263
264class PathDiagnosticBuilder : public BugReporterContext {
265  BugReport *R;
266  PathDiagnosticConsumer *PDC;
267  NodeMapClosure NMC;
268public:
269  const LocationContext *LC;
270
271  PathDiagnosticBuilder(GRBugReporter &br,
272                        BugReport *r, InterExplodedGraphMap &Backmap,
273                        PathDiagnosticConsumer *pdc)
274    : BugReporterContext(br),
275      R(r), PDC(pdc), NMC(Backmap), LC(r->getErrorNode()->getLocationContext())
276  {}
277
278  PathDiagnosticLocation ExecutionContinues(const ExplodedNode *N);
279
280  PathDiagnosticLocation ExecutionContinues(llvm::raw_string_ostream &os,
281                                            const ExplodedNode *N);
282
283  BugReport *getBugReport() { return R; }
284
285  Decl const &getCodeDecl() { return R->getErrorNode()->getCodeDecl(); }
286
287  ParentMap& getParentMap() { return LC->getParentMap(); }
288
289  const Stmt *getParent(const Stmt *S) {
290    return getParentMap().getParent(S);
291  }
292
293  virtual NodeMapClosure& getNodeResolver() { return NMC; }
294
295  PathDiagnosticLocation getEnclosingStmtLocation(const Stmt *S);
296
297  PathDiagnosticConsumer::PathGenerationScheme getGenerationScheme() const {
298    return PDC ? PDC->getGenerationScheme() : PathDiagnosticConsumer::Extensive;
299  }
300
301  bool supportsLogicalOpControlFlow() const {
302    return PDC ? PDC->supportsLogicalOpControlFlow() : true;
303  }
304};
305} // end anonymous namespace
306
307PathDiagnosticLocation
308PathDiagnosticBuilder::ExecutionContinues(const ExplodedNode *N) {
309  if (const Stmt *S = PathDiagnosticLocation::getNextStmt(N))
310    return PathDiagnosticLocation(S, getSourceManager(), LC);
311
312  return PathDiagnosticLocation::createDeclEnd(N->getLocationContext(),
313                                               getSourceManager());
314}
315
316PathDiagnosticLocation
317PathDiagnosticBuilder::ExecutionContinues(llvm::raw_string_ostream &os,
318                                          const ExplodedNode *N) {
319
320  // Slow, but probably doesn't matter.
321  if (os.str().empty())
322    os << ' ';
323
324  const PathDiagnosticLocation &Loc = ExecutionContinues(N);
325
326  if (Loc.asStmt())
327    os << "Execution continues on line "
328       << getSourceManager().getExpansionLineNumber(Loc.asLocation())
329       << '.';
330  else {
331    os << "Execution jumps to the end of the ";
332    const Decl *D = N->getLocationContext()->getDecl();
333    if (isa<ObjCMethodDecl>(D))
334      os << "method";
335    else if (isa<FunctionDecl>(D))
336      os << "function";
337    else {
338      assert(isa<BlockDecl>(D));
339      os << "anonymous block";
340    }
341    os << '.';
342  }
343
344  return Loc;
345}
346
347static bool IsNested(const Stmt *S, ParentMap &PM) {
348  if (isa<Expr>(S) && PM.isConsumedExpr(cast<Expr>(S)))
349    return true;
350
351  const Stmt *Parent = PM.getParentIgnoreParens(S);
352
353  if (Parent)
354    switch (Parent->getStmtClass()) {
355      case Stmt::ForStmtClass:
356      case Stmt::DoStmtClass:
357      case Stmt::WhileStmtClass:
358        return true;
359      default:
360        break;
361    }
362
363  return false;
364}
365
366PathDiagnosticLocation
367PathDiagnosticBuilder::getEnclosingStmtLocation(const Stmt *S) {
368  assert(S && "Null Stmt *passed to getEnclosingStmtLocation");
369  ParentMap &P = getParentMap();
370  SourceManager &SMgr = getSourceManager();
371
372  while (IsNested(S, P)) {
373    const Stmt *Parent = P.getParentIgnoreParens(S);
374
375    if (!Parent)
376      break;
377
378    switch (Parent->getStmtClass()) {
379      case Stmt::BinaryOperatorClass: {
380        const BinaryOperator *B = cast<BinaryOperator>(Parent);
381        if (B->isLogicalOp())
382          return PathDiagnosticLocation(S, SMgr, LC);
383        break;
384      }
385      case Stmt::CompoundStmtClass:
386      case Stmt::StmtExprClass:
387        return PathDiagnosticLocation(S, SMgr, LC);
388      case Stmt::ChooseExprClass:
389        // Similar to '?' if we are referring to condition, just have the edge
390        // point to the entire choose expression.
391        if (cast<ChooseExpr>(Parent)->getCond() == S)
392          return PathDiagnosticLocation(Parent, SMgr, LC);
393        else
394          return PathDiagnosticLocation(S, SMgr, LC);
395      case Stmt::BinaryConditionalOperatorClass:
396      case Stmt::ConditionalOperatorClass:
397        // For '?', if we are referring to condition, just have the edge point
398        // to the entire '?' expression.
399        if (cast<AbstractConditionalOperator>(Parent)->getCond() == S)
400          return PathDiagnosticLocation(Parent, SMgr, LC);
401        else
402          return PathDiagnosticLocation(S, SMgr, LC);
403      case Stmt::DoStmtClass:
404          return PathDiagnosticLocation(S, SMgr, LC);
405      case Stmt::ForStmtClass:
406        if (cast<ForStmt>(Parent)->getBody() == S)
407          return PathDiagnosticLocation(S, SMgr, LC);
408        break;
409      case Stmt::IfStmtClass:
410        if (cast<IfStmt>(Parent)->getCond() != S)
411          return PathDiagnosticLocation(S, SMgr, LC);
412        break;
413      case Stmt::ObjCForCollectionStmtClass:
414        if (cast<ObjCForCollectionStmt>(Parent)->getBody() == S)
415          return PathDiagnosticLocation(S, SMgr, LC);
416        break;
417      case Stmt::WhileStmtClass:
418        if (cast<WhileStmt>(Parent)->getCond() != S)
419          return PathDiagnosticLocation(S, SMgr, LC);
420        break;
421      default:
422        break;
423    }
424
425    S = Parent;
426  }
427
428  assert(S && "Cannot have null Stmt for PathDiagnosticLocation");
429
430  // Special case: DeclStmts can appear in for statement declarations, in which
431  //  case the ForStmt is the context.
432  if (isa<DeclStmt>(S)) {
433    if (const Stmt *Parent = P.getParent(S)) {
434      switch (Parent->getStmtClass()) {
435        case Stmt::ForStmtClass:
436        case Stmt::ObjCForCollectionStmtClass:
437          return PathDiagnosticLocation(Parent, SMgr, LC);
438        default:
439          break;
440      }
441    }
442  }
443  else if (isa<BinaryOperator>(S)) {
444    // Special case: the binary operator represents the initialization
445    // code in a for statement (this can happen when the variable being
446    // initialized is an old variable.
447    if (const ForStmt *FS =
448          dyn_cast_or_null<ForStmt>(P.getParentIgnoreParens(S))) {
449      if (FS->getInit() == S)
450        return PathDiagnosticLocation(FS, SMgr, LC);
451    }
452  }
453
454  return PathDiagnosticLocation(S, SMgr, LC);
455}
456
457//===----------------------------------------------------------------------===//
458// "Visitors only" path diagnostic generation algorithm.
459//===----------------------------------------------------------------------===//
460static bool GenerateVisitorsOnlyPathDiagnostic(PathDiagnostic &PD,
461                                               PathDiagnosticBuilder &PDB,
462                                               const ExplodedNode *N,
463                                      ArrayRef<BugReporterVisitor *> visitors) {
464  // All path generation skips the very first node (the error node).
465  // This is because there is special handling for the end-of-path note.
466  N = N->getFirstPred();
467  if (!N)
468    return true;
469
470  BugReport *R = PDB.getBugReport();
471  while (const ExplodedNode *Pred = N->getFirstPred()) {
472    for (ArrayRef<BugReporterVisitor *>::iterator I = visitors.begin(),
473                                                  E = visitors.end();
474         I != E; ++I) {
475      // Visit all the node pairs, but throw the path pieces away.
476      PathDiagnosticPiece *Piece = (*I)->VisitNode(N, Pred, PDB, *R);
477      delete Piece;
478    }
479
480    N = Pred;
481  }
482
483  return R->isValid();
484}
485
486//===----------------------------------------------------------------------===//
487// "Minimal" path diagnostic generation algorithm.
488//===----------------------------------------------------------------------===//
489typedef std::pair<PathDiagnosticCallPiece*, const ExplodedNode*> StackDiagPair;
490typedef SmallVector<StackDiagPair, 6> StackDiagVector;
491
492static void updateStackPiecesWithMessage(PathDiagnosticPiece *P,
493                                         StackDiagVector &CallStack) {
494  // If the piece contains a special message, add it to all the call
495  // pieces on the active stack.
496  if (PathDiagnosticEventPiece *ep =
497        dyn_cast<PathDiagnosticEventPiece>(P)) {
498
499    if (ep->hasCallStackHint())
500      for (StackDiagVector::iterator I = CallStack.begin(),
501                                     E = CallStack.end(); I != E; ++I) {
502        PathDiagnosticCallPiece *CP = I->first;
503        const ExplodedNode *N = I->second;
504        std::string stackMsg = ep->getCallStackMessage(N);
505
506        // The last message on the path to final bug is the most important
507        // one. Since we traverse the path backwards, do not add the message
508        // if one has been previously added.
509        if  (!CP->hasCallStackMessage())
510          CP->setCallStackMessage(stackMsg);
511      }
512  }
513}
514
515static void CompactPathDiagnostic(PathPieces &path, const SourceManager& SM);
516
517static bool GenerateMinimalPathDiagnostic(PathDiagnostic& PD,
518                                          PathDiagnosticBuilder &PDB,
519                                          const ExplodedNode *N,
520                                          LocationContextMap &LCM,
521                                      ArrayRef<BugReporterVisitor *> visitors) {
522
523  SourceManager& SMgr = PDB.getSourceManager();
524  const LocationContext *LC = PDB.LC;
525  const ExplodedNode *NextNode = N->pred_empty()
526                                        ? NULL : *(N->pred_begin());
527
528  StackDiagVector CallStack;
529
530  while (NextNode) {
531    N = NextNode;
532    PDB.LC = N->getLocationContext();
533    NextNode = N->getFirstPred();
534
535    ProgramPoint P = N->getLocation();
536
537    do {
538      if (Optional<CallExitEnd> CE = P.getAs<CallExitEnd>()) {
539        PathDiagnosticCallPiece *C =
540            PathDiagnosticCallPiece::construct(N, *CE, SMgr);
541        // Record the mapping from call piece to LocationContext.
542        LCM[&C->path] = CE->getCalleeContext();
543        PD.getActivePath().push_front(C);
544        PD.pushActivePath(&C->path);
545        CallStack.push_back(StackDiagPair(C, N));
546        break;
547      }
548
549      if (Optional<CallEnter> CE = P.getAs<CallEnter>()) {
550        // Flush all locations, and pop the active path.
551        bool VisitedEntireCall = PD.isWithinCall();
552        PD.popActivePath();
553
554        // Either we just added a bunch of stuff to the top-level path, or
555        // we have a previous CallExitEnd.  If the former, it means that the
556        // path terminated within a function call.  We must then take the
557        // current contents of the active path and place it within
558        // a new PathDiagnosticCallPiece.
559        PathDiagnosticCallPiece *C;
560        if (VisitedEntireCall) {
561          C = cast<PathDiagnosticCallPiece>(PD.getActivePath().front());
562        } else {
563          const Decl *Caller = CE->getLocationContext()->getDecl();
564          C = PathDiagnosticCallPiece::construct(PD.getActivePath(), Caller);
565          // Record the mapping from call piece to LocationContext.
566          LCM[&C->path] = CE->getCalleeContext();
567        }
568
569        C->setCallee(*CE, SMgr);
570        if (!CallStack.empty()) {
571          assert(CallStack.back().first == C);
572          CallStack.pop_back();
573        }
574        break;
575      }
576
577      if (Optional<BlockEdge> BE = P.getAs<BlockEdge>()) {
578        const CFGBlock *Src = BE->getSrc();
579        const CFGBlock *Dst = BE->getDst();
580        const Stmt *T = Src->getTerminator();
581
582        if (!T)
583          break;
584
585        PathDiagnosticLocation Start =
586            PathDiagnosticLocation::createBegin(T, SMgr,
587                N->getLocationContext());
588
589        switch (T->getStmtClass()) {
590        default:
591          break;
592
593        case Stmt::GotoStmtClass:
594        case Stmt::IndirectGotoStmtClass: {
595          const Stmt *S = PathDiagnosticLocation::getNextStmt(N);
596
597          if (!S)
598            break;
599
600          std::string sbuf;
601          llvm::raw_string_ostream os(sbuf);
602          const PathDiagnosticLocation &End = PDB.getEnclosingStmtLocation(S);
603
604          os << "Control jumps to line "
605              << End.asLocation().getExpansionLineNumber();
606          PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
607              Start, End, os.str()));
608          break;
609        }
610
611        case Stmt::SwitchStmtClass: {
612          // Figure out what case arm we took.
613          std::string sbuf;
614          llvm::raw_string_ostream os(sbuf);
615
616          if (const Stmt *S = Dst->getLabel()) {
617            PathDiagnosticLocation End(S, SMgr, LC);
618
619            switch (S->getStmtClass()) {
620            default:
621              os << "No cases match in the switch statement. "
622              "Control jumps to line "
623              << End.asLocation().getExpansionLineNumber();
624              break;
625            case Stmt::DefaultStmtClass:
626              os << "Control jumps to the 'default' case at line "
627              << End.asLocation().getExpansionLineNumber();
628              break;
629
630            case Stmt::CaseStmtClass: {
631              os << "Control jumps to 'case ";
632              const CaseStmt *Case = cast<CaseStmt>(S);
633              const Expr *LHS = Case->getLHS()->IgnoreParenCasts();
634
635              // Determine if it is an enum.
636              bool GetRawInt = true;
637
638              if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(LHS)) {
639                // FIXME: Maybe this should be an assertion.  Are there cases
640                // were it is not an EnumConstantDecl?
641                const EnumConstantDecl *D =
642                    dyn_cast<EnumConstantDecl>(DR->getDecl());
643
644                if (D) {
645                  GetRawInt = false;
646                  os << *D;
647                }
648              }
649
650              if (GetRawInt)
651                os << LHS->EvaluateKnownConstInt(PDB.getASTContext());
652
653              os << ":'  at line "
654                  << End.asLocation().getExpansionLineNumber();
655              break;
656            }
657            }
658            PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
659                Start, End, os.str()));
660          }
661          else {
662            os << "'Default' branch taken. ";
663            const PathDiagnosticLocation &End = PDB.ExecutionContinues(os, N);
664            PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
665                Start, End, os.str()));
666          }
667
668          break;
669        }
670
671        case Stmt::BreakStmtClass:
672        case Stmt::ContinueStmtClass: {
673          std::string sbuf;
674          llvm::raw_string_ostream os(sbuf);
675          PathDiagnosticLocation End = PDB.ExecutionContinues(os, N);
676          PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
677              Start, End, os.str()));
678          break;
679        }
680
681        // Determine control-flow for ternary '?'.
682        case Stmt::BinaryConditionalOperatorClass:
683        case Stmt::ConditionalOperatorClass: {
684          std::string sbuf;
685          llvm::raw_string_ostream os(sbuf);
686          os << "'?' condition is ";
687
688          if (*(Src->succ_begin()+1) == Dst)
689            os << "false";
690          else
691            os << "true";
692
693          PathDiagnosticLocation End = PDB.ExecutionContinues(N);
694
695          if (const Stmt *S = End.asStmt())
696            End = PDB.getEnclosingStmtLocation(S);
697
698          PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
699              Start, End, os.str()));
700          break;
701        }
702
703        // Determine control-flow for short-circuited '&&' and '||'.
704        case Stmt::BinaryOperatorClass: {
705          if (!PDB.supportsLogicalOpControlFlow())
706            break;
707
708          const BinaryOperator *B = cast<BinaryOperator>(T);
709          std::string sbuf;
710          llvm::raw_string_ostream os(sbuf);
711          os << "Left side of '";
712
713          if (B->getOpcode() == BO_LAnd) {
714            os << "&&" << "' is ";
715
716            if (*(Src->succ_begin()+1) == Dst) {
717              os << "false";
718              PathDiagnosticLocation End(B->getLHS(), SMgr, LC);
719              PathDiagnosticLocation Start =
720                  PathDiagnosticLocation::createOperatorLoc(B, SMgr);
721              PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
722                  Start, End, os.str()));
723            }
724            else {
725              os << "true";
726              PathDiagnosticLocation Start(B->getLHS(), SMgr, LC);
727              PathDiagnosticLocation End = PDB.ExecutionContinues(N);
728              PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
729                  Start, End, os.str()));
730            }
731          }
732          else {
733            assert(B->getOpcode() == BO_LOr);
734            os << "||" << "' is ";
735
736            if (*(Src->succ_begin()+1) == Dst) {
737              os << "false";
738              PathDiagnosticLocation Start(B->getLHS(), SMgr, LC);
739              PathDiagnosticLocation End = PDB.ExecutionContinues(N);
740              PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
741                  Start, End, os.str()));
742            }
743            else {
744              os << "true";
745              PathDiagnosticLocation End(B->getLHS(), SMgr, LC);
746              PathDiagnosticLocation Start =
747                  PathDiagnosticLocation::createOperatorLoc(B, SMgr);
748              PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
749                  Start, End, os.str()));
750            }
751          }
752
753          break;
754        }
755
756        case Stmt::DoStmtClass:  {
757          if (*(Src->succ_begin()) == Dst) {
758            std::string sbuf;
759            llvm::raw_string_ostream os(sbuf);
760
761            os << "Loop condition is true. ";
762            PathDiagnosticLocation End = PDB.ExecutionContinues(os, N);
763
764            if (const Stmt *S = End.asStmt())
765              End = PDB.getEnclosingStmtLocation(S);
766
767            PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
768                Start, End, os.str()));
769          }
770          else {
771            PathDiagnosticLocation End = PDB.ExecutionContinues(N);
772
773            if (const Stmt *S = End.asStmt())
774              End = PDB.getEnclosingStmtLocation(S);
775
776            PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
777                Start, End, "Loop condition is false.  Exiting loop"));
778          }
779
780          break;
781        }
782
783        case Stmt::WhileStmtClass:
784        case Stmt::ForStmtClass: {
785          if (*(Src->succ_begin()+1) == Dst) {
786            std::string sbuf;
787            llvm::raw_string_ostream os(sbuf);
788
789            os << "Loop condition is false. ";
790            PathDiagnosticLocation End = PDB.ExecutionContinues(os, N);
791            if (const Stmt *S = End.asStmt())
792              End = PDB.getEnclosingStmtLocation(S);
793
794            PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
795                Start, End, os.str()));
796          }
797          else {
798            PathDiagnosticLocation End = PDB.ExecutionContinues(N);
799            if (const Stmt *S = End.asStmt())
800              End = PDB.getEnclosingStmtLocation(S);
801
802            PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
803                Start, End, "Loop condition is true.  Entering loop body"));
804          }
805
806          break;
807        }
808
809        case Stmt::IfStmtClass: {
810          PathDiagnosticLocation End = PDB.ExecutionContinues(N);
811
812          if (const Stmt *S = End.asStmt())
813            End = PDB.getEnclosingStmtLocation(S);
814
815          if (*(Src->succ_begin()+1) == Dst)
816            PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
817                Start, End, "Taking false branch"));
818          else
819            PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(
820                Start, End, "Taking true branch"));
821
822          break;
823        }
824        }
825      }
826    } while(0);
827
828    if (NextNode) {
829      // Add diagnostic pieces from custom visitors.
830      BugReport *R = PDB.getBugReport();
831      for (ArrayRef<BugReporterVisitor *>::iterator I = visitors.begin(),
832                                                    E = visitors.end();
833           I != E; ++I) {
834        if (PathDiagnosticPiece *p = (*I)->VisitNode(N, NextNode, PDB, *R)) {
835          PD.getActivePath().push_front(p);
836          updateStackPiecesWithMessage(p, CallStack);
837        }
838      }
839    }
840  }
841
842  if (!PDB.getBugReport()->isValid())
843    return false;
844
845  // After constructing the full PathDiagnostic, do a pass over it to compact
846  // PathDiagnosticPieces that occur within a macro.
847  CompactPathDiagnostic(PD.getMutablePieces(), PDB.getSourceManager());
848  return true;
849}
850
851//===----------------------------------------------------------------------===//
852// "Extensive" PathDiagnostic generation.
853//===----------------------------------------------------------------------===//
854
855static bool IsControlFlowExpr(const Stmt *S) {
856  const Expr *E = dyn_cast<Expr>(S);
857
858  if (!E)
859    return false;
860
861  E = E->IgnoreParenCasts();
862
863  if (isa<AbstractConditionalOperator>(E))
864    return true;
865
866  if (const BinaryOperator *B = dyn_cast<BinaryOperator>(E))
867    if (B->isLogicalOp())
868      return true;
869
870  return false;
871}
872
873namespace {
874class ContextLocation : public PathDiagnosticLocation {
875  bool IsDead;
876public:
877  ContextLocation(const PathDiagnosticLocation &L, bool isdead = false)
878    : PathDiagnosticLocation(L), IsDead(isdead) {}
879
880  void markDead() { IsDead = true; }
881  bool isDead() const { return IsDead; }
882};
883
884static PathDiagnosticLocation cleanUpLocation(PathDiagnosticLocation L,
885                                              const LocationContext *LC,
886                                              bool firstCharOnly = false) {
887  if (const Stmt *S = L.asStmt()) {
888    const Stmt *Original = S;
889    while (1) {
890      // Adjust the location for some expressions that are best referenced
891      // by one of their subexpressions.
892      switch (S->getStmtClass()) {
893        default:
894          break;
895        case Stmt::ParenExprClass:
896        case Stmt::GenericSelectionExprClass:
897          S = cast<Expr>(S)->IgnoreParens();
898          firstCharOnly = true;
899          continue;
900        case Stmt::BinaryConditionalOperatorClass:
901        case Stmt::ConditionalOperatorClass:
902          S = cast<AbstractConditionalOperator>(S)->getCond();
903          firstCharOnly = true;
904          continue;
905        case Stmt::ChooseExprClass:
906          S = cast<ChooseExpr>(S)->getCond();
907          firstCharOnly = true;
908          continue;
909        case Stmt::BinaryOperatorClass:
910          S = cast<BinaryOperator>(S)->getLHS();
911          firstCharOnly = true;
912          continue;
913      }
914
915      break;
916    }
917
918    if (S != Original)
919      L = PathDiagnosticLocation(S, L.getManager(), LC);
920  }
921
922  if (firstCharOnly)
923    L  = PathDiagnosticLocation::createSingleLocation(L);
924
925  return L;
926}
927
928class EdgeBuilder {
929  std::vector<ContextLocation> CLocs;
930  typedef std::vector<ContextLocation>::iterator iterator;
931  PathDiagnostic &PD;
932  PathDiagnosticBuilder &PDB;
933  PathDiagnosticLocation PrevLoc;
934
935  bool IsConsumedExpr(const PathDiagnosticLocation &L);
936
937  bool containsLocation(const PathDiagnosticLocation &Container,
938                        const PathDiagnosticLocation &Containee);
939
940  PathDiagnosticLocation getContextLocation(const PathDiagnosticLocation &L);
941
942
943
944  void popLocation() {
945    if (!CLocs.back().isDead() && CLocs.back().asLocation().isFileID()) {
946      // For contexts, we only one the first character as the range.
947      rawAddEdge(cleanUpLocation(CLocs.back(), PDB.LC, true));
948    }
949    CLocs.pop_back();
950  }
951
952public:
953  EdgeBuilder(PathDiagnostic &pd, PathDiagnosticBuilder &pdb)
954    : PD(pd), PDB(pdb) {
955
956      // If the PathDiagnostic already has pieces, add the enclosing statement
957      // of the first piece as a context as well.
958      if (!PD.path.empty()) {
959        PrevLoc = (*PD.path.begin())->getLocation();
960
961        if (const Stmt *S = PrevLoc.asStmt())
962          addExtendedContext(PDB.getEnclosingStmtLocation(S).asStmt());
963      }
964  }
965
966  ~EdgeBuilder() {
967    while (!CLocs.empty()) popLocation();
968
969    // Finally, add an initial edge from the start location of the first
970    // statement (if it doesn't already exist).
971    PathDiagnosticLocation L = PathDiagnosticLocation::createDeclBegin(
972                                                       PDB.LC,
973                                                       PDB.getSourceManager());
974    if (L.isValid())
975      rawAddEdge(L);
976  }
977
978  void flushLocations() {
979    while (!CLocs.empty())
980      popLocation();
981    PrevLoc = PathDiagnosticLocation();
982  }
983
984  void addEdge(PathDiagnosticLocation NewLoc, bool alwaysAdd = false,
985               bool IsPostJump = false);
986
987  void rawAddEdge(PathDiagnosticLocation NewLoc);
988
989  void addContext(const Stmt *S);
990  void addContext(const PathDiagnosticLocation &L);
991  void addExtendedContext(const Stmt *S);
992};
993} // end anonymous namespace
994
995
996PathDiagnosticLocation
997EdgeBuilder::getContextLocation(const PathDiagnosticLocation &L) {
998  if (const Stmt *S = L.asStmt()) {
999    if (IsControlFlowExpr(S))
1000      return L;
1001
1002    return PDB.getEnclosingStmtLocation(S);
1003  }
1004
1005  return L;
1006}
1007
1008bool EdgeBuilder::containsLocation(const PathDiagnosticLocation &Container,
1009                                   const PathDiagnosticLocation &Containee) {
1010
1011  if (Container == Containee)
1012    return true;
1013
1014  if (Container.asDecl())
1015    return true;
1016
1017  if (const Stmt *S = Containee.asStmt())
1018    if (const Stmt *ContainerS = Container.asStmt()) {
1019      while (S) {
1020        if (S == ContainerS)
1021          return true;
1022        S = PDB.getParent(S);
1023      }
1024      return false;
1025    }
1026
1027  // Less accurate: compare using source ranges.
1028  SourceRange ContainerR = Container.asRange();
1029  SourceRange ContaineeR = Containee.asRange();
1030
1031  SourceManager &SM = PDB.getSourceManager();
1032  SourceLocation ContainerRBeg = SM.getExpansionLoc(ContainerR.getBegin());
1033  SourceLocation ContainerREnd = SM.getExpansionLoc(ContainerR.getEnd());
1034  SourceLocation ContaineeRBeg = SM.getExpansionLoc(ContaineeR.getBegin());
1035  SourceLocation ContaineeREnd = SM.getExpansionLoc(ContaineeR.getEnd());
1036
1037  unsigned ContainerBegLine = SM.getExpansionLineNumber(ContainerRBeg);
1038  unsigned ContainerEndLine = SM.getExpansionLineNumber(ContainerREnd);
1039  unsigned ContaineeBegLine = SM.getExpansionLineNumber(ContaineeRBeg);
1040  unsigned ContaineeEndLine = SM.getExpansionLineNumber(ContaineeREnd);
1041
1042  assert(ContainerBegLine <= ContainerEndLine);
1043  assert(ContaineeBegLine <= ContaineeEndLine);
1044
1045  return (ContainerBegLine <= ContaineeBegLine &&
1046          ContainerEndLine >= ContaineeEndLine &&
1047          (ContainerBegLine != ContaineeBegLine ||
1048           SM.getExpansionColumnNumber(ContainerRBeg) <=
1049           SM.getExpansionColumnNumber(ContaineeRBeg)) &&
1050          (ContainerEndLine != ContaineeEndLine ||
1051           SM.getExpansionColumnNumber(ContainerREnd) >=
1052           SM.getExpansionColumnNumber(ContaineeREnd)));
1053}
1054
1055void EdgeBuilder::rawAddEdge(PathDiagnosticLocation NewLoc) {
1056  if (!PrevLoc.isValid()) {
1057    PrevLoc = NewLoc;
1058    return;
1059  }
1060
1061  const PathDiagnosticLocation &NewLocClean = cleanUpLocation(NewLoc, PDB.LC);
1062  const PathDiagnosticLocation &PrevLocClean = cleanUpLocation(PrevLoc, PDB.LC);
1063
1064  if (PrevLocClean.asLocation().isInvalid()) {
1065    PrevLoc = NewLoc;
1066    return;
1067  }
1068
1069  if (NewLocClean.asLocation() == PrevLocClean.asLocation())
1070    return;
1071
1072  // FIXME: Ignore intra-macro edges for now.
1073  if (NewLocClean.asLocation().getExpansionLoc() ==
1074      PrevLocClean.asLocation().getExpansionLoc())
1075    return;
1076
1077  PD.getActivePath().push_front(new PathDiagnosticControlFlowPiece(NewLocClean, PrevLocClean));
1078  PrevLoc = NewLoc;
1079}
1080
1081void EdgeBuilder::addEdge(PathDiagnosticLocation NewLoc, bool alwaysAdd,
1082                          bool IsPostJump) {
1083
1084  if (!alwaysAdd && NewLoc.asLocation().isMacroID())
1085    return;
1086
1087  const PathDiagnosticLocation &CLoc = getContextLocation(NewLoc);
1088
1089  while (!CLocs.empty()) {
1090    ContextLocation &TopContextLoc = CLocs.back();
1091
1092    // Is the top location context the same as the one for the new location?
1093    if (TopContextLoc == CLoc) {
1094      if (alwaysAdd) {
1095        if (IsConsumedExpr(TopContextLoc))
1096          TopContextLoc.markDead();
1097
1098        rawAddEdge(NewLoc);
1099      }
1100
1101      if (IsPostJump)
1102        TopContextLoc.markDead();
1103      return;
1104    }
1105
1106    if (containsLocation(TopContextLoc, CLoc)) {
1107      if (alwaysAdd) {
1108        rawAddEdge(NewLoc);
1109
1110        if (IsConsumedExpr(CLoc)) {
1111          CLocs.push_back(ContextLocation(CLoc, /*IsDead=*/true));
1112          return;
1113        }
1114      }
1115
1116      CLocs.push_back(ContextLocation(CLoc, /*IsDead=*/IsPostJump));
1117      return;
1118    }
1119
1120    // Context does not contain the location.  Flush it.
1121    popLocation();
1122  }
1123
1124  // If we reach here, there is no enclosing context.  Just add the edge.
1125  rawAddEdge(NewLoc);
1126}
1127
1128bool EdgeBuilder::IsConsumedExpr(const PathDiagnosticLocation &L) {
1129  if (const Expr *X = dyn_cast_or_null<Expr>(L.asStmt()))
1130    return PDB.getParentMap().isConsumedExpr(X) && !IsControlFlowExpr(X);
1131
1132  return false;
1133}
1134
1135void EdgeBuilder::addExtendedContext(const Stmt *S) {
1136  if (!S)
1137    return;
1138
1139  const Stmt *Parent = PDB.getParent(S);
1140  while (Parent) {
1141    if (isa<CompoundStmt>(Parent))
1142      Parent = PDB.getParent(Parent);
1143    else
1144      break;
1145  }
1146
1147  if (Parent) {
1148    switch (Parent->getStmtClass()) {
1149      case Stmt::DoStmtClass:
1150      case Stmt::ObjCAtSynchronizedStmtClass:
1151        addContext(Parent);
1152      default:
1153        break;
1154    }
1155  }
1156
1157  addContext(S);
1158}
1159
1160void EdgeBuilder::addContext(const Stmt *S) {
1161  if (!S)
1162    return;
1163
1164  PathDiagnosticLocation L(S, PDB.getSourceManager(), PDB.LC);
1165  addContext(L);
1166}
1167
1168void EdgeBuilder::addContext(const PathDiagnosticLocation &L) {
1169  while (!CLocs.empty()) {
1170    const PathDiagnosticLocation &TopContextLoc = CLocs.back();
1171
1172    // Is the top location context the same as the one for the new location?
1173    if (TopContextLoc == L)
1174      return;
1175
1176    if (containsLocation(TopContextLoc, L)) {
1177      CLocs.push_back(L);
1178      return;
1179    }
1180
1181    // Context does not contain the location.  Flush it.
1182    popLocation();
1183  }
1184
1185  CLocs.push_back(L);
1186}
1187
1188// Cone-of-influence: support the reverse propagation of "interesting" symbols
1189// and values by tracing interesting calculations backwards through evaluated
1190// expressions along a path.  This is probably overly complicated, but the idea
1191// is that if an expression computed an "interesting" value, the child
1192// expressions are are also likely to be "interesting" as well (which then
1193// propagates to the values they in turn compute).  This reverse propagation
1194// is needed to track interesting correlations across function call boundaries,
1195// where formal arguments bind to actual arguments, etc.  This is also needed
1196// because the constraint solver sometimes simplifies certain symbolic values
1197// into constants when appropriate, and this complicates reasoning about
1198// interesting values.
1199typedef llvm::DenseSet<const Expr *> InterestingExprs;
1200
1201static void reversePropagateIntererstingSymbols(BugReport &R,
1202                                                InterestingExprs &IE,
1203                                                const ProgramState *State,
1204                                                const Expr *Ex,
1205                                                const LocationContext *LCtx) {
1206  SVal V = State->getSVal(Ex, LCtx);
1207  if (!(R.isInteresting(V) || IE.count(Ex)))
1208    return;
1209
1210  switch (Ex->getStmtClass()) {
1211    default:
1212      if (!isa<CastExpr>(Ex))
1213        break;
1214      // Fall through.
1215    case Stmt::BinaryOperatorClass:
1216    case Stmt::UnaryOperatorClass: {
1217      for (Stmt::const_child_iterator CI = Ex->child_begin(),
1218            CE = Ex->child_end();
1219            CI != CE; ++CI) {
1220        if (const Expr *child = dyn_cast_or_null<Expr>(*CI)) {
1221          IE.insert(child);
1222          SVal ChildV = State->getSVal(child, LCtx);
1223          R.markInteresting(ChildV);
1224        }
1225        break;
1226      }
1227    }
1228  }
1229
1230  R.markInteresting(V);
1231}
1232
1233static void reversePropagateInterestingSymbols(BugReport &R,
1234                                               InterestingExprs &IE,
1235                                               const ProgramState *State,
1236                                               const LocationContext *CalleeCtx,
1237                                               const LocationContext *CallerCtx)
1238{
1239  // FIXME: Handle non-CallExpr-based CallEvents.
1240  const StackFrameContext *Callee = CalleeCtx->getCurrentStackFrame();
1241  const Stmt *CallSite = Callee->getCallSite();
1242  if (const CallExpr *CE = dyn_cast_or_null<CallExpr>(CallSite)) {
1243    if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CalleeCtx->getDecl())) {
1244      FunctionDecl::param_const_iterator PI = FD->param_begin(),
1245                                         PE = FD->param_end();
1246      CallExpr::const_arg_iterator AI = CE->arg_begin(), AE = CE->arg_end();
1247      for (; AI != AE && PI != PE; ++AI, ++PI) {
1248        if (const Expr *ArgE = *AI) {
1249          if (const ParmVarDecl *PD = *PI) {
1250            Loc LV = State->getLValue(PD, CalleeCtx);
1251            if (R.isInteresting(LV) || R.isInteresting(State->getRawSVal(LV)))
1252              IE.insert(ArgE);
1253          }
1254        }
1255      }
1256    }
1257  }
1258}
1259
1260//===----------------------------------------------------------------------===//
1261// Functions for determining if a loop was executed 0 times.
1262//===----------------------------------------------------------------------===//
1263
1264static bool isLoop(const Stmt *Term) {
1265  switch (Term->getStmtClass()) {
1266    case Stmt::ForStmtClass:
1267    case Stmt::WhileStmtClass:
1268    case Stmt::ObjCForCollectionStmtClass:
1269      return true;
1270    default:
1271      // Note that we intentionally do not include do..while here.
1272      return false;
1273  }
1274}
1275
1276static bool isJumpToFalseBranch(const BlockEdge *BE) {
1277  const CFGBlock *Src = BE->getSrc();
1278  assert(Src->succ_size() == 2);
1279  return (*(Src->succ_begin()+1) == BE->getDst());
1280}
1281
1282/// Return true if the terminator is a loop and the destination is the
1283/// false branch.
1284static bool isLoopJumpPastBody(const Stmt *Term, const BlockEdge *BE) {
1285  if (!isLoop(Term))
1286    return false;
1287
1288  // Did we take the false branch?
1289  return isJumpToFalseBranch(BE);
1290}
1291
1292static bool isContainedByStmt(ParentMap &PM, const Stmt *S, const Stmt *SubS) {
1293  while (SubS) {
1294    if (SubS == S)
1295      return true;
1296    SubS = PM.getParent(SubS);
1297  }
1298  return false;
1299}
1300
1301static const Stmt *getStmtBeforeCond(ParentMap &PM, const Stmt *Term,
1302                                     const ExplodedNode *N) {
1303  while (N) {
1304    Optional<StmtPoint> SP = N->getLocation().getAs<StmtPoint>();
1305    if (SP) {
1306      const Stmt *S = SP->getStmt();
1307      if (!isContainedByStmt(PM, Term, S))
1308        return S;
1309    }
1310    N = N->getFirstPred();
1311  }
1312  return 0;
1313}
1314
1315static bool isInLoopBody(ParentMap &PM, const Stmt *S, const Stmt *Term) {
1316  const Stmt *LoopBody = 0;
1317  switch (Term->getStmtClass()) {
1318    case Stmt::ForStmtClass: {
1319      const ForStmt *FS = cast<ForStmt>(Term);
1320      if (isContainedByStmt(PM, FS->getInc(), S))
1321        return true;
1322      LoopBody = FS->getBody();
1323      break;
1324    }
1325    case Stmt::ObjCForCollectionStmtClass: {
1326      const ObjCForCollectionStmt *FC = cast<ObjCForCollectionStmt>(Term);
1327      LoopBody = FC->getBody();
1328      break;
1329    }
1330    case Stmt::WhileStmtClass:
1331      LoopBody = cast<WhileStmt>(Term)->getBody();
1332      break;
1333    default:
1334      return false;
1335  }
1336  return isContainedByStmt(PM, LoopBody, S);
1337}
1338
1339//===----------------------------------------------------------------------===//
1340// Top-level logic for generating extensive path diagnostics.
1341//===----------------------------------------------------------------------===//
1342
1343static bool GenerateExtensivePathDiagnostic(PathDiagnostic& PD,
1344                                            PathDiagnosticBuilder &PDB,
1345                                            const ExplodedNode *N,
1346                                            LocationContextMap &LCM,
1347                                      ArrayRef<BugReporterVisitor *> visitors) {
1348  EdgeBuilder EB(PD, PDB);
1349  const SourceManager& SM = PDB.getSourceManager();
1350  StackDiagVector CallStack;
1351  InterestingExprs IE;
1352
1353  const ExplodedNode *NextNode = N->pred_empty() ? NULL : *(N->pred_begin());
1354  while (NextNode) {
1355    N = NextNode;
1356    NextNode = N->getFirstPred();
1357    ProgramPoint P = N->getLocation();
1358
1359    do {
1360      if (Optional<PostStmt> PS = P.getAs<PostStmt>()) {
1361        if (const Expr *Ex = PS->getStmtAs<Expr>())
1362          reversePropagateIntererstingSymbols(*PDB.getBugReport(), IE,
1363                                              N->getState().getPtr(), Ex,
1364                                              N->getLocationContext());
1365      }
1366
1367      if (Optional<CallExitEnd> CE = P.getAs<CallExitEnd>()) {
1368        const Stmt *S = CE->getCalleeContext()->getCallSite();
1369        if (const Expr *Ex = dyn_cast_or_null<Expr>(S)) {
1370            reversePropagateIntererstingSymbols(*PDB.getBugReport(), IE,
1371                                                N->getState().getPtr(), Ex,
1372                                                N->getLocationContext());
1373        }
1374
1375        PathDiagnosticCallPiece *C =
1376          PathDiagnosticCallPiece::construct(N, *CE, SM);
1377        LCM[&C->path] = CE->getCalleeContext();
1378
1379        EB.addEdge(C->callReturn, /*AlwaysAdd=*/true, /*IsPostJump=*/true);
1380        EB.flushLocations();
1381
1382        PD.getActivePath().push_front(C);
1383        PD.pushActivePath(&C->path);
1384        CallStack.push_back(StackDiagPair(C, N));
1385        break;
1386      }
1387
1388      // Pop the call hierarchy if we are done walking the contents
1389      // of a function call.
1390      if (Optional<CallEnter> CE = P.getAs<CallEnter>()) {
1391        // Add an edge to the start of the function.
1392        const Decl *D = CE->getCalleeContext()->getDecl();
1393        PathDiagnosticLocation pos =
1394          PathDiagnosticLocation::createBegin(D, SM);
1395        EB.addEdge(pos);
1396
1397        // Flush all locations, and pop the active path.
1398        bool VisitedEntireCall = PD.isWithinCall();
1399        EB.flushLocations();
1400        PD.popActivePath();
1401        PDB.LC = N->getLocationContext();
1402
1403        // Either we just added a bunch of stuff to the top-level path, or
1404        // we have a previous CallExitEnd.  If the former, it means that the
1405        // path terminated within a function call.  We must then take the
1406        // current contents of the active path and place it within
1407        // a new PathDiagnosticCallPiece.
1408        PathDiagnosticCallPiece *C;
1409        if (VisitedEntireCall) {
1410          C = cast<PathDiagnosticCallPiece>(PD.getActivePath().front());
1411        } else {
1412          const Decl *Caller = CE->getLocationContext()->getDecl();
1413          C = PathDiagnosticCallPiece::construct(PD.getActivePath(), Caller);
1414          LCM[&C->path] = CE->getCalleeContext();
1415        }
1416
1417        C->setCallee(*CE, SM);
1418        EB.addContext(C->getLocation());
1419
1420        if (!CallStack.empty()) {
1421          assert(CallStack.back().first == C);
1422          CallStack.pop_back();
1423        }
1424        break;
1425      }
1426
1427      // Note that is important that we update the LocationContext
1428      // after looking at CallExits.  CallExit basically adds an
1429      // edge in the *caller*, so we don't want to update the LocationContext
1430      // too soon.
1431      PDB.LC = N->getLocationContext();
1432
1433      // Block edges.
1434      if (Optional<BlockEdge> BE = P.getAs<BlockEdge>()) {
1435        // Does this represent entering a call?  If so, look at propagating
1436        // interesting symbols across call boundaries.
1437        if (NextNode) {
1438          const LocationContext *CallerCtx = NextNode->getLocationContext();
1439          const LocationContext *CalleeCtx = PDB.LC;
1440          if (CallerCtx != CalleeCtx) {
1441            reversePropagateInterestingSymbols(*PDB.getBugReport(), IE,
1442                                               N->getState().getPtr(),
1443                                               CalleeCtx, CallerCtx);
1444          }
1445        }
1446
1447        // Are we jumping to the head of a loop?  Add a special diagnostic.
1448        if (const Stmt *Loop = BE->getSrc()->getLoopTarget()) {
1449          PathDiagnosticLocation L(Loop, SM, PDB.LC);
1450          const CompoundStmt *CS = NULL;
1451
1452          if (const ForStmt *FS = dyn_cast<ForStmt>(Loop))
1453            CS = dyn_cast<CompoundStmt>(FS->getBody());
1454          else if (const WhileStmt *WS = dyn_cast<WhileStmt>(Loop))
1455            CS = dyn_cast<CompoundStmt>(WS->getBody());
1456
1457          PathDiagnosticEventPiece *p =
1458            new PathDiagnosticEventPiece(L,
1459                                        "Looping back to the head of the loop");
1460          p->setPrunable(true);
1461
1462          EB.addEdge(p->getLocation(), true);
1463          PD.getActivePath().push_front(p);
1464
1465          if (CS) {
1466            PathDiagnosticLocation BL =
1467              PathDiagnosticLocation::createEndBrace(CS, SM);
1468            EB.addEdge(BL);
1469          }
1470        }
1471
1472        const CFGBlock *BSrc = BE->getSrc();
1473        ParentMap &PM = PDB.getParentMap();
1474
1475        if (const Stmt *Term = BSrc->getTerminator()) {
1476          // Are we jumping past the loop body without ever executing the
1477          // loop (because the condition was false)?
1478          if (isLoopJumpPastBody(Term, &*BE) &&
1479              !isInLoopBody(PM,
1480                            getStmtBeforeCond(PM,
1481                                              BSrc->getTerminatorCondition(),
1482                                              N),
1483                            Term)) {
1484            PathDiagnosticLocation L(Term, SM, PDB.LC);
1485            PathDiagnosticEventPiece *PE =
1486                new PathDiagnosticEventPiece(L, "Loop body executed 0 times");
1487            PE->setPrunable(true);
1488
1489            EB.addEdge(PE->getLocation(), true);
1490            PD.getActivePath().push_front(PE);
1491          }
1492
1493          // In any case, add the terminator as the current statement
1494          // context for control edges.
1495          EB.addContext(Term);
1496        }
1497
1498        break;
1499      }
1500
1501      if (Optional<BlockEntrance> BE = P.getAs<BlockEntrance>()) {
1502        Optional<CFGElement> First = BE->getFirstElement();
1503        if (Optional<CFGStmt> S = First ? First->getAs<CFGStmt>() : None) {
1504          const Stmt *stmt = S->getStmt();
1505          if (IsControlFlowExpr(stmt)) {
1506            // Add the proper context for '&&', '||', and '?'.
1507            EB.addContext(stmt);
1508          }
1509          else
1510            EB.addExtendedContext(PDB.getEnclosingStmtLocation(stmt).asStmt());
1511        }
1512
1513        break;
1514      }
1515
1516
1517    } while (0);
1518
1519    if (!NextNode)
1520      continue;
1521
1522    // Add pieces from custom visitors.
1523    BugReport *R = PDB.getBugReport();
1524    for (ArrayRef<BugReporterVisitor *>::iterator I = visitors.begin(),
1525                                                  E = visitors.end();
1526         I != E; ++I) {
1527      if (PathDiagnosticPiece *p = (*I)->VisitNode(N, NextNode, PDB, *R)) {
1528        const PathDiagnosticLocation &Loc = p->getLocation();
1529        EB.addEdge(Loc, true);
1530        PD.getActivePath().push_front(p);
1531        updateStackPiecesWithMessage(p, CallStack);
1532
1533        if (const Stmt *S = Loc.asStmt())
1534          EB.addExtendedContext(PDB.getEnclosingStmtLocation(S).asStmt());
1535      }
1536    }
1537  }
1538
1539  return PDB.getBugReport()->isValid();
1540}
1541
1542/// \brief Adds a sanitized control-flow diagnostic edge to a path.
1543static void addEdgeToPath(PathPieces &path,
1544                          PathDiagnosticLocation &PrevLoc,
1545                          PathDiagnosticLocation NewLoc,
1546                          const LocationContext *LC) {
1547  if (!NewLoc.isValid())
1548    return;
1549
1550  SourceLocation NewLocL = NewLoc.asLocation();
1551  if (NewLocL.isInvalid() || NewLocL.isMacroID())
1552    return;
1553
1554  if (!PrevLoc.isValid()) {
1555    PrevLoc = NewLoc;
1556    return;
1557  }
1558
1559  // FIXME: ignore intra-macro edges for now.
1560  if (NewLoc.asLocation().getExpansionLoc() ==
1561      PrevLoc.asLocation().getExpansionLoc())
1562    return;
1563
1564  path.push_front(new PathDiagnosticControlFlowPiece(NewLoc,
1565                                                     PrevLoc));
1566  PrevLoc = NewLoc;
1567}
1568
1569enum EventCategorization { EC_None, EC_EnterLoop, EC_LoopingBack };
1570
1571typedef llvm::DenseMap<const PathDiagnosticEventPiece *,
1572                       enum EventCategorization>
1573        EventCategoryMap;
1574
1575
1576static void pruneLoopEvents(PathPieces &path, EventCategoryMap &ECM) {
1577  for (PathPieces::iterator I = path.begin(), E = path.end(); I != E; ++I) {
1578    if (PathDiagnosticCallPiece *call = dyn_cast<PathDiagnosticCallPiece>(*I)) {
1579      pruneLoopEvents(call->path, ECM);
1580      continue;
1581    }
1582
1583    PathDiagnosticEventPiece *I_event = dyn_cast<PathDiagnosticEventPiece>(*I);
1584    if (!I_event || ECM[I_event] != EC_LoopingBack)
1585      continue;
1586
1587    PathPieces::iterator Next = I; ++Next;
1588    PathDiagnosticEventPiece *Next_event = 0;
1589    for ( ; Next != E ; ++Next) {
1590      Next_event = dyn_cast<PathDiagnosticEventPiece>(*Next);
1591      if (Next_event)
1592        break;
1593    }
1594
1595    if (Next_event) {
1596      EventCategorization E = ECM[Next_event];
1597      if (E == EC_EnterLoop) {
1598        PathDiagnosticLocation L = I_event->getLocation();
1599        PathDiagnosticLocation L_next = Next_event->getLocation();
1600        if (L == L_next) {
1601          path.erase(Next);
1602        }
1603      }
1604    }
1605  }
1606}
1607
1608static bool
1609GenerateAlternateExtensivePathDiagnostic(PathDiagnostic& PD,
1610                                         PathDiagnosticBuilder &PDB,
1611                                         const ExplodedNode *N,
1612                                         LocationContextMap &LCM,
1613                                      ArrayRef<BugReporterVisitor *> visitors) {
1614
1615  BugReport *report = PDB.getBugReport();
1616  const SourceManager& SM = PDB.getSourceManager();
1617  StackDiagVector CallStack;
1618  InterestingExprs IE;
1619
1620  // Record the last location for a given visited stack frame.
1621  llvm::DenseMap<const StackFrameContext *, PathDiagnosticLocation>
1622    PrevLocMap;
1623
1624  EventCategoryMap EventCategory;
1625
1626  const ExplodedNode *NextNode = N->getFirstPred();
1627  while (NextNode) {
1628    N = NextNode;
1629    NextNode = N->getFirstPred();
1630    ProgramPoint P = N->getLocation();
1631    const LocationContext *LC = N->getLocationContext();
1632    assert(!LCM[&PD.getActivePath()] || LCM[&PD.getActivePath()] == LC);
1633    LCM[&PD.getActivePath()] = LC;
1634    PathDiagnosticLocation &PrevLoc = PrevLocMap[LC->getCurrentStackFrame()];
1635
1636    do {
1637      if (Optional<PostStmt> PS = P.getAs<PostStmt>()) {
1638        // For expressions, make sure we propagate the
1639        // interesting symbols correctly.
1640        if (const Expr *Ex = PS->getStmtAs<Expr>())
1641          reversePropagateIntererstingSymbols(*PDB.getBugReport(), IE,
1642                                              N->getState().getPtr(), Ex,
1643                                              N->getLocationContext());
1644
1645        PathDiagnosticLocation L =
1646          PathDiagnosticLocation(PS->getStmt(), SM, LC);
1647        addEdgeToPath(PD.getActivePath(), PrevLoc, L, LC);
1648        break;
1649      }
1650
1651      // Have we encountered an exit from a function call?
1652      if (Optional<CallExitEnd> CE = P.getAs<CallExitEnd>()) {
1653        const Stmt *S = CE->getCalleeContext()->getCallSite();
1654        // Propagate the interesting symbols accordingly.
1655        if (const Expr *Ex = dyn_cast_or_null<Expr>(S)) {
1656          reversePropagateIntererstingSymbols(*PDB.getBugReport(), IE,
1657                                              N->getState().getPtr(), Ex,
1658                                              N->getLocationContext());
1659        }
1660
1661        // We are descending into a call (backwards).  Construct
1662        // a new call piece to contain the path pieces for that call.
1663        PathDiagnosticCallPiece *C =
1664          PathDiagnosticCallPiece::construct(N, *CE, SM);
1665
1666        // Record the location context for this call piece.
1667        LCM[&C->path] = CE->getCalleeContext();
1668
1669        // Add the edge to the return site.
1670        addEdgeToPath(PD.getActivePath(), PrevLoc, C->callReturn, LC);
1671
1672        // Make the contents of the call the active path for now.
1673        PD.pushActivePath(&C->path);
1674        CallStack.push_back(StackDiagPair(C, N));
1675        break;
1676      }
1677
1678      // Have we encountered an entrance to a call?  It may be
1679      // the case that we have not encountered a matching
1680      // call exit before this point.  This means that the path
1681      // terminated within the call itself.
1682      if (Optional<CallEnter> CE = P.getAs<CallEnter>()) {
1683        // Add an edge to the start of the function.
1684        const Decl *D = CE->getCalleeContext()->getDecl();
1685        addEdgeToPath(PD.getActivePath(), PrevLoc,
1686                      PathDiagnosticLocation::createBegin(D, SM), LC);
1687
1688        // Did we visit an entire call?
1689        bool VisitedEntireCall = PD.isWithinCall();
1690        PD.popActivePath();
1691
1692        PathDiagnosticCallPiece *C;
1693        if (VisitedEntireCall) {
1694          C = cast<PathDiagnosticCallPiece>(PD.getActivePath().front());
1695        } else {
1696          const Decl *Caller = CE->getLocationContext()->getDecl();
1697          C = PathDiagnosticCallPiece::construct(PD.getActivePath(), Caller);
1698          LCM[&C->path] = CE->getCalleeContext();
1699        }
1700        C->setCallee(*CE, SM);
1701
1702        if (!CallStack.empty()) {
1703          assert(CallStack.back().first == C);
1704          CallStack.pop_back();
1705        }
1706        break;
1707      }
1708
1709      // Block edges.
1710      if (Optional<BlockEdge> BE = P.getAs<BlockEdge>()) {
1711        // Does this represent entering a call?  If so, look at propagating
1712        // interesting symbols across call boundaries.
1713        if (NextNode) {
1714          const LocationContext *CallerCtx = NextNode->getLocationContext();
1715          const LocationContext *CalleeCtx = PDB.LC;
1716          if (CallerCtx != CalleeCtx) {
1717            reversePropagateInterestingSymbols(*PDB.getBugReport(), IE,
1718                                               N->getState().getPtr(),
1719                                               CalleeCtx, CallerCtx);
1720          }
1721        }
1722
1723        // Are we jumping to the head of a loop?  Add a special diagnostic.
1724        if (const Stmt *Loop = BE->getSrc()->getLoopTarget()) {
1725          PathDiagnosticLocation L(Loop, SM, PDB.LC);
1726
1727          PathDiagnosticEventPiece *p =
1728            new PathDiagnosticEventPiece(L, "Looping back to the head "
1729                                            "of the loop");
1730          p->setPrunable(true);
1731
1732          addEdgeToPath(PD.getActivePath(), PrevLoc, p->getLocation(), LC);
1733          PD.getActivePath().push_front(p);
1734          EventCategory[p] = EC_LoopingBack;
1735        }
1736
1737        const CFGBlock *BSrc = BE->getSrc();
1738        ParentMap &PM = PDB.getParentMap();
1739
1740        if (const Stmt *Term = BSrc->getTerminator()) {
1741          // Are we jumping past the loop body without ever executing the
1742          // loop (because the condition was false)?
1743          if (isLoop(Term)) {
1744            const Stmt *TermCond = BSrc->getTerminatorCondition();
1745            bool IsInLoopBody =
1746              isInLoopBody(PM, getStmtBeforeCond(PM, TermCond, N), Term);
1747
1748            const char *str = 0;
1749            enum EventCategorization EC = EC_None;
1750
1751            if (isJumpToFalseBranch(&*BE)) {
1752              if (!IsInLoopBody) {
1753                str = "Loop body executed 0 times";
1754              }
1755            }
1756            else {
1757              str = "Entering loop body";
1758              EC = EC_EnterLoop;
1759            }
1760
1761            if (str) {
1762              PathDiagnosticLocation L(TermCond, SM, PDB.LC);
1763              PathDiagnosticEventPiece *PE =
1764                new PathDiagnosticEventPiece(L, str);
1765              EventCategory[PE] = EC;
1766              PE->setPrunable(true);
1767              addEdgeToPath(PD.getActivePath(), PrevLoc,
1768                            PE->getLocation(), LC);
1769              PD.getActivePath().push_front(PE);
1770            }
1771          }
1772          else if (isa<BreakStmt>(Term) || isa<ContinueStmt>(Term) ||
1773                   isa<GotoStmt>(Term)) {
1774            PathDiagnosticLocation L(Term, SM, PDB.LC);
1775            addEdgeToPath(PD.getActivePath(), PrevLoc, L, LC);
1776          }
1777        }
1778        break;
1779      }
1780    } while (0);
1781
1782    if (!NextNode)
1783      continue;
1784
1785    // Add pieces from custom visitors.
1786    for (ArrayRef<BugReporterVisitor *>::iterator I = visitors.begin(),
1787         E = visitors.end();
1788         I != E; ++I) {
1789      if (PathDiagnosticPiece *p = (*I)->VisitNode(N, NextNode, PDB, *report)) {
1790        addEdgeToPath(PD.getActivePath(), PrevLoc, p->getLocation(), LC);
1791        PD.getActivePath().push_front(p);
1792        updateStackPiecesWithMessage(p, CallStack);
1793      }
1794    }
1795  }
1796
1797  if (report->isValid()) {
1798    // Prune redundant loop diagnostics.
1799    pruneLoopEvents(PD.getMutablePieces(), EventCategory);
1800  }
1801
1802  return report->isValid();
1803}
1804
1805const Stmt *getLocStmt(PathDiagnosticLocation L) {
1806  if (!L.isValid())
1807    return 0;
1808  return L.asStmt();
1809}
1810
1811const Stmt *getStmtParent(const Stmt *S, ParentMap &PM) {
1812  if (!S)
1813    return 0;
1814  return PM.getParentIgnoreParens(S);
1815}
1816
1817static bool isConditionForTerminator(const Stmt *S, const Stmt *Cond) {
1818  // Note that we intentionally to do not handle || and && here.
1819  switch (S->getStmtClass()) {
1820    case Stmt::IfStmtClass:
1821      return cast<IfStmt>(S)->getCond() == Cond;
1822    case Stmt::ForStmtClass:
1823      return cast<ForStmt>(S)->getCond() == Cond;
1824    case Stmt::WhileStmtClass:
1825      return cast<WhileStmt>(S)->getCond() == Cond;
1826    case Stmt::DoStmtClass:
1827      return cast<DoStmt>(S)->getCond() == Cond;
1828    case Stmt::ChooseExprClass:
1829      return cast<ChooseExpr>(S)->getCond() == Cond;
1830    case Stmt::IndirectGotoStmtClass:
1831      return cast<IndirectGotoStmt>(S)->getTarget() == Cond;
1832    case Stmt::SwitchStmtClass:
1833      return cast<SwitchStmt>(S)->getCond() == Cond;
1834    case Stmt::BinaryConditionalOperatorClass:
1835      return cast<BinaryConditionalOperator>(S)->getCond() == Cond;
1836    case Stmt::ConditionalOperatorClass:
1837      return cast<ConditionalOperator>(S)->getCond() == Cond;
1838    case Stmt::ObjCForCollectionStmtClass:
1839      return cast<ObjCForCollectionStmt>(S)->getElement() == Cond;
1840    default:
1841      return false;
1842  }
1843}
1844
1845static bool isIncrementOrInitInForLoop(const Stmt *S, const Stmt *FL) {
1846  const ForStmt *FS = dyn_cast<ForStmt>(FL);
1847  if (!FS)
1848    return false;
1849  return FS->getInc() == S || FS->getInit() == S;
1850}
1851
1852typedef llvm::DenseSet<const PathDiagnosticCallPiece *>
1853        OptimizedCallsSet;
1854
1855static bool optimizeEdges(PathPieces &path, SourceManager &SM,
1856                          OptimizedCallsSet &OCS,
1857                          LocationContextMap &LCM) {
1858  bool hasChanges = false;
1859  const LocationContext *LC = LCM[&path];
1860  assert(LC);
1861  bool isFirst = true;
1862
1863  for (PathPieces::iterator I = path.begin(), E = path.end(); I != E; ) {
1864    bool wasFirst = isFirst;
1865    isFirst = false;
1866
1867    // Optimize subpaths.
1868    if (PathDiagnosticCallPiece *CallI = dyn_cast<PathDiagnosticCallPiece>(*I)){
1869      // Record the fact that a call has been optimized so we only do the
1870      // effort once.
1871      if (!OCS.count(CallI)) {
1872        while (optimizeEdges(CallI->path, SM, OCS, LCM)) {}
1873        OCS.insert(CallI);
1874      }
1875      ++I;
1876      continue;
1877    }
1878
1879    // Pattern match the current piece and its successor.
1880    PathDiagnosticControlFlowPiece *PieceI =
1881      dyn_cast<PathDiagnosticControlFlowPiece>(*I);
1882
1883    if (!PieceI) {
1884      ++I;
1885      continue;
1886    }
1887
1888    ParentMap &PM = LC->getParentMap();
1889    const Stmt *s1Start = getLocStmt(PieceI->getStartLocation());
1890    const Stmt *s1End   = getLocStmt(PieceI->getEndLocation());
1891    const Stmt *level1 = getStmtParent(s1Start, PM);
1892    const Stmt *level2 = getStmtParent(s1End, PM);
1893
1894    if (wasFirst) {
1895      // If the first edge (in isolation) is just a transition from
1896      // an expression to a parent expression then eliminate that edge.
1897      if (level1 && level2 && level2 == PM.getParent(level1)) {
1898        path.erase(I);
1899        // Since we are erasing the current edge at the start of the
1900        // path, just return now so we start analyzing the start of the path
1901        // again.
1902        return true;
1903      }
1904
1905      // If the first edge (in isolation) is a transition from the
1906      // initialization or increment in a for loop then remove it.
1907      if (level1 && isIncrementOrInitInForLoop(s1Start, level1)) {
1908        path.erase(I);
1909        return true;
1910      }
1911    }
1912
1913    PathPieces::iterator NextI = I; ++NextI;
1914    if (NextI == E)
1915      break;
1916
1917    PathDiagnosticControlFlowPiece *PieceNextI =
1918      dyn_cast<PathDiagnosticControlFlowPiece>(*NextI);
1919
1920    if (!PieceNextI) {
1921      ++I;
1922      continue;
1923    }
1924
1925    const Stmt *s2Start = getLocStmt(PieceNextI->getStartLocation());
1926    const Stmt *s2End   = getLocStmt(PieceNextI->getEndLocation());
1927    const Stmt *level3 = getStmtParent(s2Start, PM);
1928    const Stmt *level4 = getStmtParent(s2End, PM);
1929
1930    // Rule I.
1931    //
1932    // If we have two consecutive control edges whose end/begin locations
1933    // are at the same level (e.g. statements or top-level expressions within
1934    // a compound statement, or siblings share a single ancestor expression),
1935    // then merge them if they have no interesting intermediate event.
1936    //
1937    // For example:
1938    //
1939    // (1.1 -> 1.2) -> (1.2 -> 1.3) becomes (1.1 -> 1.3) because the common
1940    // parent is '1'.  Here 'x.y.z' represents the hierarchy of statements.
1941    //
1942    // NOTE: this will be limited later in cases where we add barriers
1943    // to prevent this optimization.
1944    //
1945    if (level1 && level1 == level2 && level1 == level3 && level1 == level4) {
1946      PieceI->setEndLocation(PieceNextI->getEndLocation());
1947      path.erase(NextI);
1948      hasChanges = true;
1949      continue;
1950    }
1951
1952    // Rule II.
1953    //
1954    // Eliminate edges between subexpressions and parent expressions
1955    // when the subexpression is consumed.
1956    //
1957    // NOTE: this will be limited later in cases where we add barriers
1958    // to prevent this optimization.
1959    //
1960    if (s1End && s1End == s2Start && level2) {
1961      if (isIncrementOrInitInForLoop(s1End, level2) ||
1962          (isa<Expr>(s1End) && PM.isConsumedExpr(cast<Expr>(s1End)) &&
1963            !isConditionForTerminator(level2, s1End)))
1964      {
1965        PieceI->setEndLocation(PieceNextI->getEndLocation());
1966        path.erase(NextI);
1967        hasChanges = true;
1968        continue;
1969      }
1970    }
1971
1972    // No changes at this index?  Move to the next one.
1973    ++I;
1974  }
1975
1976  // No changes.
1977  return hasChanges;
1978}
1979
1980//===----------------------------------------------------------------------===//
1981// Methods for BugType and subclasses.
1982//===----------------------------------------------------------------------===//
1983BugType::~BugType() { }
1984
1985void BugType::FlushReports(BugReporter &BR) {}
1986
1987void BuiltinBug::anchor() {}
1988
1989//===----------------------------------------------------------------------===//
1990// Methods for BugReport and subclasses.
1991//===----------------------------------------------------------------------===//
1992
1993void BugReport::NodeResolver::anchor() {}
1994
1995void BugReport::addVisitor(BugReporterVisitor* visitor) {
1996  if (!visitor)
1997    return;
1998
1999  llvm::FoldingSetNodeID ID;
2000  visitor->Profile(ID);
2001  void *InsertPos;
2002
2003  if (CallbacksSet.FindNodeOrInsertPos(ID, InsertPos)) {
2004    delete visitor;
2005    return;
2006  }
2007
2008  CallbacksSet.InsertNode(visitor, InsertPos);
2009  Callbacks.push_back(visitor);
2010  ++ConfigurationChangeToken;
2011}
2012
2013BugReport::~BugReport() {
2014  for (visitor_iterator I = visitor_begin(), E = visitor_end(); I != E; ++I) {
2015    delete *I;
2016  }
2017  while (!interestingSymbols.empty()) {
2018    popInterestingSymbolsAndRegions();
2019  }
2020}
2021
2022const Decl *BugReport::getDeclWithIssue() const {
2023  if (DeclWithIssue)
2024    return DeclWithIssue;
2025
2026  const ExplodedNode *N = getErrorNode();
2027  if (!N)
2028    return 0;
2029
2030  const LocationContext *LC = N->getLocationContext();
2031  return LC->getCurrentStackFrame()->getDecl();
2032}
2033
2034void BugReport::Profile(llvm::FoldingSetNodeID& hash) const {
2035  hash.AddPointer(&BT);
2036  hash.AddString(Description);
2037  PathDiagnosticLocation UL = getUniqueingLocation();
2038  if (UL.isValid()) {
2039    UL.Profile(hash);
2040  } else if (Location.isValid()) {
2041    Location.Profile(hash);
2042  } else {
2043    assert(ErrorNode);
2044    hash.AddPointer(GetCurrentOrPreviousStmt(ErrorNode));
2045  }
2046
2047  for (SmallVectorImpl<SourceRange>::const_iterator I =
2048      Ranges.begin(), E = Ranges.end(); I != E; ++I) {
2049    const SourceRange range = *I;
2050    if (!range.isValid())
2051      continue;
2052    hash.AddInteger(range.getBegin().getRawEncoding());
2053    hash.AddInteger(range.getEnd().getRawEncoding());
2054  }
2055}
2056
2057void BugReport::markInteresting(SymbolRef sym) {
2058  if (!sym)
2059    return;
2060
2061  // If the symbol wasn't already in our set, note a configuration change.
2062  if (getInterestingSymbols().insert(sym).second)
2063    ++ConfigurationChangeToken;
2064
2065  if (const SymbolMetadata *meta = dyn_cast<SymbolMetadata>(sym))
2066    getInterestingRegions().insert(meta->getRegion());
2067}
2068
2069void BugReport::markInteresting(const MemRegion *R) {
2070  if (!R)
2071    return;
2072
2073  // If the base region wasn't already in our set, note a configuration change.
2074  R = R->getBaseRegion();
2075  if (getInterestingRegions().insert(R).second)
2076    ++ConfigurationChangeToken;
2077
2078  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R))
2079    getInterestingSymbols().insert(SR->getSymbol());
2080}
2081
2082void BugReport::markInteresting(SVal V) {
2083  markInteresting(V.getAsRegion());
2084  markInteresting(V.getAsSymbol());
2085}
2086
2087void BugReport::markInteresting(const LocationContext *LC) {
2088  if (!LC)
2089    return;
2090  InterestingLocationContexts.insert(LC);
2091}
2092
2093bool BugReport::isInteresting(SVal V) {
2094  return isInteresting(V.getAsRegion()) || isInteresting(V.getAsSymbol());
2095}
2096
2097bool BugReport::isInteresting(SymbolRef sym) {
2098  if (!sym)
2099    return false;
2100  // We don't currently consider metadata symbols to be interesting
2101  // even if we know their region is interesting. Is that correct behavior?
2102  return getInterestingSymbols().count(sym);
2103}
2104
2105bool BugReport::isInteresting(const MemRegion *R) {
2106  if (!R)
2107    return false;
2108  R = R->getBaseRegion();
2109  bool b = getInterestingRegions().count(R);
2110  if (b)
2111    return true;
2112  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R))
2113    return getInterestingSymbols().count(SR->getSymbol());
2114  return false;
2115}
2116
2117bool BugReport::isInteresting(const LocationContext *LC) {
2118  if (!LC)
2119    return false;
2120  return InterestingLocationContexts.count(LC);
2121}
2122
2123void BugReport::lazyInitializeInterestingSets() {
2124  if (interestingSymbols.empty()) {
2125    interestingSymbols.push_back(new Symbols());
2126    interestingRegions.push_back(new Regions());
2127  }
2128}
2129
2130BugReport::Symbols &BugReport::getInterestingSymbols() {
2131  lazyInitializeInterestingSets();
2132  return *interestingSymbols.back();
2133}
2134
2135BugReport::Regions &BugReport::getInterestingRegions() {
2136  lazyInitializeInterestingSets();
2137  return *interestingRegions.back();
2138}
2139
2140void BugReport::pushInterestingSymbolsAndRegions() {
2141  interestingSymbols.push_back(new Symbols(getInterestingSymbols()));
2142  interestingRegions.push_back(new Regions(getInterestingRegions()));
2143}
2144
2145void BugReport::popInterestingSymbolsAndRegions() {
2146  delete interestingSymbols.back();
2147  interestingSymbols.pop_back();
2148  delete interestingRegions.back();
2149  interestingRegions.pop_back();
2150}
2151
2152const Stmt *BugReport::getStmt() const {
2153  if (!ErrorNode)
2154    return 0;
2155
2156  ProgramPoint ProgP = ErrorNode->getLocation();
2157  const Stmt *S = NULL;
2158
2159  if (Optional<BlockEntrance> BE = ProgP.getAs<BlockEntrance>()) {
2160    CFGBlock &Exit = ProgP.getLocationContext()->getCFG()->getExit();
2161    if (BE->getBlock() == &Exit)
2162      S = GetPreviousStmt(ErrorNode);
2163  }
2164  if (!S)
2165    S = PathDiagnosticLocation::getStmt(ErrorNode);
2166
2167  return S;
2168}
2169
2170std::pair<BugReport::ranges_iterator, BugReport::ranges_iterator>
2171BugReport::getRanges() {
2172    // If no custom ranges, add the range of the statement corresponding to
2173    // the error node.
2174    if (Ranges.empty()) {
2175      if (const Expr *E = dyn_cast_or_null<Expr>(getStmt()))
2176        addRange(E->getSourceRange());
2177      else
2178        return std::make_pair(ranges_iterator(), ranges_iterator());
2179    }
2180
2181    // User-specified absence of range info.
2182    if (Ranges.size() == 1 && !Ranges.begin()->isValid())
2183      return std::make_pair(ranges_iterator(), ranges_iterator());
2184
2185    return std::make_pair(Ranges.begin(), Ranges.end());
2186}
2187
2188PathDiagnosticLocation BugReport::getLocation(const SourceManager &SM) const {
2189  if (ErrorNode) {
2190    assert(!Location.isValid() &&
2191     "Either Location or ErrorNode should be specified but not both.");
2192    return PathDiagnosticLocation::createEndOfPath(ErrorNode, SM);
2193  } else {
2194    assert(Location.isValid());
2195    return Location;
2196  }
2197
2198  return PathDiagnosticLocation();
2199}
2200
2201//===----------------------------------------------------------------------===//
2202// Methods for BugReporter and subclasses.
2203//===----------------------------------------------------------------------===//
2204
2205BugReportEquivClass::~BugReportEquivClass() { }
2206GRBugReporter::~GRBugReporter() { }
2207BugReporterData::~BugReporterData() {}
2208
2209ExplodedGraph &GRBugReporter::getGraph() { return Eng.getGraph(); }
2210
2211ProgramStateManager&
2212GRBugReporter::getStateManager() { return Eng.getStateManager(); }
2213
2214BugReporter::~BugReporter() {
2215  FlushReports();
2216
2217  // Free the bug reports we are tracking.
2218  typedef std::vector<BugReportEquivClass *> ContTy;
2219  for (ContTy::iterator I = EQClassesVector.begin(), E = EQClassesVector.end();
2220       I != E; ++I) {
2221    delete *I;
2222  }
2223}
2224
2225void BugReporter::FlushReports() {
2226  if (BugTypes.isEmpty())
2227    return;
2228
2229  // First flush the warnings for each BugType.  This may end up creating new
2230  // warnings and new BugTypes.
2231  // FIXME: Only NSErrorChecker needs BugType's FlushReports.
2232  // Turn NSErrorChecker into a proper checker and remove this.
2233  SmallVector<const BugType*, 16> bugTypes;
2234  for (BugTypesTy::iterator I=BugTypes.begin(), E=BugTypes.end(); I!=E; ++I)
2235    bugTypes.push_back(*I);
2236  for (SmallVector<const BugType*, 16>::iterator
2237         I = bugTypes.begin(), E = bugTypes.end(); I != E; ++I)
2238    const_cast<BugType*>(*I)->FlushReports(*this);
2239
2240  // We need to flush reports in deterministic order to ensure the order
2241  // of the reports is consistent between runs.
2242  typedef std::vector<BugReportEquivClass *> ContVecTy;
2243  for (ContVecTy::iterator EI=EQClassesVector.begin(), EE=EQClassesVector.end();
2244       EI != EE; ++EI){
2245    BugReportEquivClass& EQ = **EI;
2246    FlushReport(EQ);
2247  }
2248
2249  // BugReporter owns and deletes only BugTypes created implicitly through
2250  // EmitBasicReport.
2251  // FIXME: There are leaks from checkers that assume that the BugTypes they
2252  // create will be destroyed by the BugReporter.
2253  for (llvm::StringMap<BugType*>::iterator
2254         I = StrBugTypes.begin(), E = StrBugTypes.end(); I != E; ++I)
2255    delete I->second;
2256
2257  // Remove all references to the BugType objects.
2258  BugTypes = F.getEmptySet();
2259}
2260
2261//===----------------------------------------------------------------------===//
2262// PathDiagnostics generation.
2263//===----------------------------------------------------------------------===//
2264
2265namespace {
2266/// A wrapper around a report graph, which contains only a single path, and its
2267/// node maps.
2268class ReportGraph {
2269public:
2270  InterExplodedGraphMap BackMap;
2271  OwningPtr<ExplodedGraph> Graph;
2272  const ExplodedNode *ErrorNode;
2273  size_t Index;
2274};
2275
2276/// A wrapper around a trimmed graph and its node maps.
2277class TrimmedGraph {
2278  InterExplodedGraphMap InverseMap;
2279
2280  typedef llvm::DenseMap<const ExplodedNode *, unsigned> PriorityMapTy;
2281  PriorityMapTy PriorityMap;
2282
2283  typedef std::pair<const ExplodedNode *, size_t> NodeIndexPair;
2284  SmallVector<NodeIndexPair, 32> ReportNodes;
2285
2286  OwningPtr<ExplodedGraph> G;
2287
2288  /// A helper class for sorting ExplodedNodes by priority.
2289  template <bool Descending>
2290  class PriorityCompare {
2291    const PriorityMapTy &PriorityMap;
2292
2293  public:
2294    PriorityCompare(const PriorityMapTy &M) : PriorityMap(M) {}
2295
2296    bool operator()(const ExplodedNode *LHS, const ExplodedNode *RHS) const {
2297      PriorityMapTy::const_iterator LI = PriorityMap.find(LHS);
2298      PriorityMapTy::const_iterator RI = PriorityMap.find(RHS);
2299      PriorityMapTy::const_iterator E = PriorityMap.end();
2300
2301      if (LI == E)
2302        return Descending;
2303      if (RI == E)
2304        return !Descending;
2305
2306      return Descending ? LI->second > RI->second
2307                        : LI->second < RI->second;
2308    }
2309
2310    bool operator()(const NodeIndexPair &LHS, const NodeIndexPair &RHS) const {
2311      return (*this)(LHS.first, RHS.first);
2312    }
2313  };
2314
2315public:
2316  TrimmedGraph(const ExplodedGraph *OriginalGraph,
2317               ArrayRef<const ExplodedNode *> Nodes);
2318
2319  bool popNextReportGraph(ReportGraph &GraphWrapper);
2320};
2321}
2322
2323TrimmedGraph::TrimmedGraph(const ExplodedGraph *OriginalGraph,
2324                           ArrayRef<const ExplodedNode *> Nodes) {
2325  // The trimmed graph is created in the body of the constructor to ensure
2326  // that the DenseMaps have been initialized already.
2327  InterExplodedGraphMap ForwardMap;
2328  G.reset(OriginalGraph->trim(Nodes, &ForwardMap, &InverseMap));
2329
2330  // Find the (first) error node in the trimmed graph.  We just need to consult
2331  // the node map which maps from nodes in the original graph to nodes
2332  // in the new graph.
2333  llvm::SmallPtrSet<const ExplodedNode *, 32> RemainingNodes;
2334
2335  for (unsigned i = 0, count = Nodes.size(); i < count; ++i) {
2336    if (const ExplodedNode *NewNode = ForwardMap.lookup(Nodes[i])) {
2337      ReportNodes.push_back(std::make_pair(NewNode, i));
2338      RemainingNodes.insert(NewNode);
2339    }
2340  }
2341
2342  assert(!RemainingNodes.empty() && "No error node found in the trimmed graph");
2343
2344  // Perform a forward BFS to find all the shortest paths.
2345  std::queue<const ExplodedNode *> WS;
2346
2347  assert(G->num_roots() == 1);
2348  WS.push(*G->roots_begin());
2349  unsigned Priority = 0;
2350
2351  while (!WS.empty()) {
2352    const ExplodedNode *Node = WS.front();
2353    WS.pop();
2354
2355    PriorityMapTy::iterator PriorityEntry;
2356    bool IsNew;
2357    llvm::tie(PriorityEntry, IsNew) =
2358      PriorityMap.insert(std::make_pair(Node, Priority));
2359    ++Priority;
2360
2361    if (!IsNew) {
2362      assert(PriorityEntry->second <= Priority);
2363      continue;
2364    }
2365
2366    if (RemainingNodes.erase(Node))
2367      if (RemainingNodes.empty())
2368        break;
2369
2370    for (ExplodedNode::const_pred_iterator I = Node->succ_begin(),
2371                                           E = Node->succ_end();
2372         I != E; ++I)
2373      WS.push(*I);
2374  }
2375
2376  // Sort the error paths from longest to shortest.
2377  std::sort(ReportNodes.begin(), ReportNodes.end(),
2378            PriorityCompare<true>(PriorityMap));
2379}
2380
2381bool TrimmedGraph::popNextReportGraph(ReportGraph &GraphWrapper) {
2382  if (ReportNodes.empty())
2383    return false;
2384
2385  const ExplodedNode *OrigN;
2386  llvm::tie(OrigN, GraphWrapper.Index) = ReportNodes.pop_back_val();
2387  assert(PriorityMap.find(OrigN) != PriorityMap.end() &&
2388         "error node not accessible from root");
2389
2390  // Create a new graph with a single path.  This is the graph
2391  // that will be returned to the caller.
2392  ExplodedGraph *GNew = new ExplodedGraph();
2393  GraphWrapper.Graph.reset(GNew);
2394  GraphWrapper.BackMap.clear();
2395
2396  // Now walk from the error node up the BFS path, always taking the
2397  // predeccessor with the lowest number.
2398  ExplodedNode *Succ = 0;
2399  while (true) {
2400    // Create the equivalent node in the new graph with the same state
2401    // and location.
2402    ExplodedNode *NewN = GNew->getNode(OrigN->getLocation(), OrigN->getState(),
2403                                       OrigN->isSink());
2404
2405    // Store the mapping to the original node.
2406    InterExplodedGraphMap::const_iterator IMitr = InverseMap.find(OrigN);
2407    assert(IMitr != InverseMap.end() && "No mapping to original node.");
2408    GraphWrapper.BackMap[NewN] = IMitr->second;
2409
2410    // Link up the new node with the previous node.
2411    if (Succ)
2412      Succ->addPredecessor(NewN, *GNew);
2413    else
2414      GraphWrapper.ErrorNode = NewN;
2415
2416    Succ = NewN;
2417
2418    // Are we at the final node?
2419    if (OrigN->pred_empty()) {
2420      GNew->addRoot(NewN);
2421      break;
2422    }
2423
2424    // Find the next predeccessor node.  We choose the node that is marked
2425    // with the lowest BFS number.
2426    OrigN = *std::min_element(OrigN->pred_begin(), OrigN->pred_end(),
2427                          PriorityCompare<false>(PriorityMap));
2428  }
2429
2430  return true;
2431}
2432
2433
2434/// CompactPathDiagnostic - This function postprocesses a PathDiagnostic object
2435///  and collapses PathDiagosticPieces that are expanded by macros.
2436static void CompactPathDiagnostic(PathPieces &path, const SourceManager& SM) {
2437  typedef std::vector<std::pair<IntrusiveRefCntPtr<PathDiagnosticMacroPiece>,
2438                                SourceLocation> > MacroStackTy;
2439
2440  typedef std::vector<IntrusiveRefCntPtr<PathDiagnosticPiece> >
2441          PiecesTy;
2442
2443  MacroStackTy MacroStack;
2444  PiecesTy Pieces;
2445
2446  for (PathPieces::const_iterator I = path.begin(), E = path.end();
2447       I!=E; ++I) {
2448
2449    PathDiagnosticPiece *piece = I->getPtr();
2450
2451    // Recursively compact calls.
2452    if (PathDiagnosticCallPiece *call=dyn_cast<PathDiagnosticCallPiece>(piece)){
2453      CompactPathDiagnostic(call->path, SM);
2454    }
2455
2456    // Get the location of the PathDiagnosticPiece.
2457    const FullSourceLoc Loc = piece->getLocation().asLocation();
2458
2459    // Determine the instantiation location, which is the location we group
2460    // related PathDiagnosticPieces.
2461    SourceLocation InstantiationLoc = Loc.isMacroID() ?
2462                                      SM.getExpansionLoc(Loc) :
2463                                      SourceLocation();
2464
2465    if (Loc.isFileID()) {
2466      MacroStack.clear();
2467      Pieces.push_back(piece);
2468      continue;
2469    }
2470
2471    assert(Loc.isMacroID());
2472
2473    // Is the PathDiagnosticPiece within the same macro group?
2474    if (!MacroStack.empty() && InstantiationLoc == MacroStack.back().second) {
2475      MacroStack.back().first->subPieces.push_back(piece);
2476      continue;
2477    }
2478
2479    // We aren't in the same group.  Are we descending into a new macro
2480    // or are part of an old one?
2481    IntrusiveRefCntPtr<PathDiagnosticMacroPiece> MacroGroup;
2482
2483    SourceLocation ParentInstantiationLoc = InstantiationLoc.isMacroID() ?
2484                                          SM.getExpansionLoc(Loc) :
2485                                          SourceLocation();
2486
2487    // Walk the entire macro stack.
2488    while (!MacroStack.empty()) {
2489      if (InstantiationLoc == MacroStack.back().second) {
2490        MacroGroup = MacroStack.back().first;
2491        break;
2492      }
2493
2494      if (ParentInstantiationLoc == MacroStack.back().second) {
2495        MacroGroup = MacroStack.back().first;
2496        break;
2497      }
2498
2499      MacroStack.pop_back();
2500    }
2501
2502    if (!MacroGroup || ParentInstantiationLoc == MacroStack.back().second) {
2503      // Create a new macro group and add it to the stack.
2504      PathDiagnosticMacroPiece *NewGroup =
2505        new PathDiagnosticMacroPiece(
2506          PathDiagnosticLocation::createSingleLocation(piece->getLocation()));
2507
2508      if (MacroGroup)
2509        MacroGroup->subPieces.push_back(NewGroup);
2510      else {
2511        assert(InstantiationLoc.isFileID());
2512        Pieces.push_back(NewGroup);
2513      }
2514
2515      MacroGroup = NewGroup;
2516      MacroStack.push_back(std::make_pair(MacroGroup, InstantiationLoc));
2517    }
2518
2519    // Finally, add the PathDiagnosticPiece to the group.
2520    MacroGroup->subPieces.push_back(piece);
2521  }
2522
2523  // Now take the pieces and construct a new PathDiagnostic.
2524  path.clear();
2525
2526  for (PiecesTy::iterator I=Pieces.begin(), E=Pieces.end(); I!=E; ++I)
2527    path.push_back(*I);
2528}
2529
2530bool GRBugReporter::generatePathDiagnostic(PathDiagnostic& PD,
2531                                           PathDiagnosticConsumer &PC,
2532                                           ArrayRef<BugReport *> &bugReports) {
2533  assert(!bugReports.empty());
2534
2535  bool HasValid = false;
2536  bool HasInvalid = false;
2537  SmallVector<const ExplodedNode *, 32> errorNodes;
2538  for (ArrayRef<BugReport*>::iterator I = bugReports.begin(),
2539                                      E = bugReports.end(); I != E; ++I) {
2540    if ((*I)->isValid()) {
2541      HasValid = true;
2542      errorNodes.push_back((*I)->getErrorNode());
2543    } else {
2544      // Keep the errorNodes list in sync with the bugReports list.
2545      HasInvalid = true;
2546      errorNodes.push_back(0);
2547    }
2548  }
2549
2550  // If all the reports have been marked invalid by a previous path generation,
2551  // we're done.
2552  if (!HasValid)
2553    return false;
2554
2555  typedef PathDiagnosticConsumer::PathGenerationScheme PathGenerationScheme;
2556  PathGenerationScheme ActiveScheme = PC.getGenerationScheme();
2557
2558  if (ActiveScheme == PathDiagnosticConsumer::Extensive) {
2559    AnalyzerOptions &options = getEngine().getAnalysisManager().options;
2560    if (options.getBooleanOption("path-diagnostics-alternate", false)) {
2561      ActiveScheme = PathDiagnosticConsumer::AlternateExtensive;
2562    }
2563  }
2564
2565  TrimmedGraph TrimG(&getGraph(), errorNodes);
2566  ReportGraph ErrorGraph;
2567
2568  while (TrimG.popNextReportGraph(ErrorGraph)) {
2569    // Find the BugReport with the original location.
2570    assert(ErrorGraph.Index < bugReports.size());
2571    BugReport *R = bugReports[ErrorGraph.Index];
2572    assert(R && "No original report found for sliced graph.");
2573    assert(R->isValid() && "Report selected by trimmed graph marked invalid.");
2574
2575    // Start building the path diagnostic...
2576    PathDiagnosticBuilder PDB(*this, R, ErrorGraph.BackMap, &PC);
2577    const ExplodedNode *N = ErrorGraph.ErrorNode;
2578
2579    // Register additional node visitors.
2580    R->addVisitor(new NilReceiverBRVisitor());
2581    R->addVisitor(new ConditionBRVisitor());
2582    R->addVisitor(new LikelyFalsePositiveSuppressionBRVisitor());
2583
2584    BugReport::VisitorList visitors;
2585    unsigned origReportConfigToken, finalReportConfigToken;
2586    LocationContextMap LCM;
2587
2588    // While generating diagnostics, it's possible the visitors will decide
2589    // new symbols and regions are interesting, or add other visitors based on
2590    // the information they find. If they do, we need to regenerate the path
2591    // based on our new report configuration.
2592    do {
2593      // Get a clean copy of all the visitors.
2594      for (BugReport::visitor_iterator I = R->visitor_begin(),
2595                                       E = R->visitor_end(); I != E; ++I)
2596        visitors.push_back((*I)->clone());
2597
2598      // Clear out the active path from any previous work.
2599      PD.resetPath();
2600      origReportConfigToken = R->getConfigurationChangeToken();
2601
2602      // Generate the very last diagnostic piece - the piece is visible before
2603      // the trace is expanded.
2604      PathDiagnosticPiece *LastPiece = 0;
2605      for (BugReport::visitor_iterator I = visitors.begin(), E = visitors.end();
2606          I != E; ++I) {
2607        if (PathDiagnosticPiece *Piece = (*I)->getEndPath(PDB, N, *R)) {
2608          assert (!LastPiece &&
2609              "There can only be one final piece in a diagnostic.");
2610          LastPiece = Piece;
2611        }
2612      }
2613
2614      if (ActiveScheme != PathDiagnosticConsumer::None) {
2615        if (!LastPiece)
2616          LastPiece = BugReporterVisitor::getDefaultEndPath(PDB, N, *R);
2617        assert(LastPiece);
2618        PD.setEndOfPath(LastPiece);
2619      }
2620
2621      // Make sure we get a clean location context map so we don't
2622      // hold onto old mappings.
2623      LCM.clear();
2624
2625      switch (ActiveScheme) {
2626      case PathDiagnosticConsumer::AlternateExtensive:
2627        GenerateAlternateExtensivePathDiagnostic(PD, PDB, N, LCM, visitors);
2628        break;
2629      case PathDiagnosticConsumer::Extensive:
2630        GenerateExtensivePathDiagnostic(PD, PDB, N, LCM, visitors);
2631        break;
2632      case PathDiagnosticConsumer::Minimal:
2633        GenerateMinimalPathDiagnostic(PD, PDB, N, LCM, visitors);
2634        break;
2635      case PathDiagnosticConsumer::None:
2636        GenerateVisitorsOnlyPathDiagnostic(PD, PDB, N, visitors);
2637        break;
2638      }
2639
2640      // Clean up the visitors we used.
2641      llvm::DeleteContainerPointers(visitors);
2642
2643      // Did anything change while generating this path?
2644      finalReportConfigToken = R->getConfigurationChangeToken();
2645    } while (finalReportConfigToken != origReportConfigToken);
2646
2647    if (!R->isValid())
2648      continue;
2649
2650    // Finally, prune the diagnostic path of uninteresting stuff.
2651    if (!PD.path.empty()) {
2652      // Remove messages that are basically the same.
2653      removeRedundantMsgs(PD.getMutablePieces());
2654
2655      if (R->shouldPrunePath() &&
2656          getEngine().getAnalysisManager().options.shouldPrunePaths()) {
2657        bool stillHasNotes = removeUnneededCalls(PD.getMutablePieces(), R, LCM);
2658        assert(stillHasNotes);
2659        (void)stillHasNotes;
2660      }
2661
2662      adjustCallLocations(PD.getMutablePieces());
2663
2664      if (ActiveScheme == PathDiagnosticConsumer::AlternateExtensive) {
2665        OptimizedCallsSet OCS;
2666        while (optimizeEdges(PD.getMutablePieces(), getSourceManager(),
2667                             OCS, LCM)) {}
2668      }
2669    }
2670
2671    // We found a report and didn't suppress it.
2672    return true;
2673  }
2674
2675  // We suppressed all the reports in this equivalence class.
2676  assert(!HasInvalid && "Inconsistent suppression");
2677  (void)HasInvalid;
2678  return false;
2679}
2680
2681void BugReporter::Register(BugType *BT) {
2682  BugTypes = F.add(BugTypes, BT);
2683}
2684
2685void BugReporter::emitReport(BugReport* R) {
2686  // Compute the bug report's hash to determine its equivalence class.
2687  llvm::FoldingSetNodeID ID;
2688  R->Profile(ID);
2689
2690  // Lookup the equivance class.  If there isn't one, create it.
2691  BugType& BT = R->getBugType();
2692  Register(&BT);
2693  void *InsertPos;
2694  BugReportEquivClass* EQ = EQClasses.FindNodeOrInsertPos(ID, InsertPos);
2695
2696  if (!EQ) {
2697    EQ = new BugReportEquivClass(R);
2698    EQClasses.InsertNode(EQ, InsertPos);
2699    EQClassesVector.push_back(EQ);
2700  }
2701  else
2702    EQ->AddReport(R);
2703}
2704
2705
2706//===----------------------------------------------------------------------===//
2707// Emitting reports in equivalence classes.
2708//===----------------------------------------------------------------------===//
2709
2710namespace {
2711struct FRIEC_WLItem {
2712  const ExplodedNode *N;
2713  ExplodedNode::const_succ_iterator I, E;
2714
2715  FRIEC_WLItem(const ExplodedNode *n)
2716  : N(n), I(N->succ_begin()), E(N->succ_end()) {}
2717};
2718}
2719
2720static BugReport *
2721FindReportInEquivalenceClass(BugReportEquivClass& EQ,
2722                             SmallVectorImpl<BugReport*> &bugReports) {
2723
2724  BugReportEquivClass::iterator I = EQ.begin(), E = EQ.end();
2725  assert(I != E);
2726  BugType& BT = I->getBugType();
2727
2728  // If we don't need to suppress any of the nodes because they are
2729  // post-dominated by a sink, simply add all the nodes in the equivalence class
2730  // to 'Nodes'.  Any of the reports will serve as a "representative" report.
2731  if (!BT.isSuppressOnSink()) {
2732    BugReport *R = I;
2733    for (BugReportEquivClass::iterator I=EQ.begin(), E=EQ.end(); I!=E; ++I) {
2734      const ExplodedNode *N = I->getErrorNode();
2735      if (N) {
2736        R = I;
2737        bugReports.push_back(R);
2738      }
2739    }
2740    return R;
2741  }
2742
2743  // For bug reports that should be suppressed when all paths are post-dominated
2744  // by a sink node, iterate through the reports in the equivalence class
2745  // until we find one that isn't post-dominated (if one exists).  We use a
2746  // DFS traversal of the ExplodedGraph to find a non-sink node.  We could write
2747  // this as a recursive function, but we don't want to risk blowing out the
2748  // stack for very long paths.
2749  BugReport *exampleReport = 0;
2750
2751  for (; I != E; ++I) {
2752    const ExplodedNode *errorNode = I->getErrorNode();
2753
2754    if (!errorNode)
2755      continue;
2756    if (errorNode->isSink()) {
2757      llvm_unreachable(
2758           "BugType::isSuppressSink() should not be 'true' for sink end nodes");
2759    }
2760    // No successors?  By definition this nodes isn't post-dominated by a sink.
2761    if (errorNode->succ_empty()) {
2762      bugReports.push_back(I);
2763      if (!exampleReport)
2764        exampleReport = I;
2765      continue;
2766    }
2767
2768    // At this point we know that 'N' is not a sink and it has at least one
2769    // successor.  Use a DFS worklist to find a non-sink end-of-path node.
2770    typedef FRIEC_WLItem WLItem;
2771    typedef SmallVector<WLItem, 10> DFSWorkList;
2772    llvm::DenseMap<const ExplodedNode *, unsigned> Visited;
2773
2774    DFSWorkList WL;
2775    WL.push_back(errorNode);
2776    Visited[errorNode] = 1;
2777
2778    while (!WL.empty()) {
2779      WLItem &WI = WL.back();
2780      assert(!WI.N->succ_empty());
2781
2782      for (; WI.I != WI.E; ++WI.I) {
2783        const ExplodedNode *Succ = *WI.I;
2784        // End-of-path node?
2785        if (Succ->succ_empty()) {
2786          // If we found an end-of-path node that is not a sink.
2787          if (!Succ->isSink()) {
2788            bugReports.push_back(I);
2789            if (!exampleReport)
2790              exampleReport = I;
2791            WL.clear();
2792            break;
2793          }
2794          // Found a sink?  Continue on to the next successor.
2795          continue;
2796        }
2797        // Mark the successor as visited.  If it hasn't been explored,
2798        // enqueue it to the DFS worklist.
2799        unsigned &mark = Visited[Succ];
2800        if (!mark) {
2801          mark = 1;
2802          WL.push_back(Succ);
2803          break;
2804        }
2805      }
2806
2807      // The worklist may have been cleared at this point.  First
2808      // check if it is empty before checking the last item.
2809      if (!WL.empty() && &WL.back() == &WI)
2810        WL.pop_back();
2811    }
2812  }
2813
2814  // ExampleReport will be NULL if all the nodes in the equivalence class
2815  // were post-dominated by sinks.
2816  return exampleReport;
2817}
2818
2819void BugReporter::FlushReport(BugReportEquivClass& EQ) {
2820  SmallVector<BugReport*, 10> bugReports;
2821  BugReport *exampleReport = FindReportInEquivalenceClass(EQ, bugReports);
2822  if (exampleReport) {
2823    const PathDiagnosticConsumers &C = getPathDiagnosticConsumers();
2824    for (PathDiagnosticConsumers::const_iterator I=C.begin(),
2825                                                 E=C.end(); I != E; ++I) {
2826      FlushReport(exampleReport, **I, bugReports);
2827    }
2828  }
2829}
2830
2831void BugReporter::FlushReport(BugReport *exampleReport,
2832                              PathDiagnosticConsumer &PD,
2833                              ArrayRef<BugReport*> bugReports) {
2834
2835  // FIXME: Make sure we use the 'R' for the path that was actually used.
2836  // Probably doesn't make a difference in practice.
2837  BugType& BT = exampleReport->getBugType();
2838
2839  OwningPtr<PathDiagnostic>
2840    D(new PathDiagnostic(exampleReport->getDeclWithIssue(),
2841                         exampleReport->getBugType().getName(),
2842                         exampleReport->getDescription(),
2843                         exampleReport->getShortDescription(/*Fallback=*/false),
2844                         BT.getCategory(),
2845                         exampleReport->getUniqueingLocation(),
2846                         exampleReport->getUniqueingDecl()));
2847
2848  MaxBugClassSize = std::max(bugReports.size(),
2849                             static_cast<size_t>(MaxBugClassSize));
2850
2851  // Generate the full path diagnostic, using the generation scheme
2852  // specified by the PathDiagnosticConsumer. Note that we have to generate
2853  // path diagnostics even for consumers which do not support paths, because
2854  // the BugReporterVisitors may mark this bug as a false positive.
2855  if (!bugReports.empty())
2856    if (!generatePathDiagnostic(*D.get(), PD, bugReports))
2857      return;
2858
2859  MaxValidBugClassSize = std::max(bugReports.size(),
2860                                  static_cast<size_t>(MaxValidBugClassSize));
2861
2862  // If the path is empty, generate a single step path with the location
2863  // of the issue.
2864  if (D->path.empty()) {
2865    PathDiagnosticLocation L = exampleReport->getLocation(getSourceManager());
2866    PathDiagnosticPiece *piece =
2867      new PathDiagnosticEventPiece(L, exampleReport->getDescription());
2868    BugReport::ranges_iterator Beg, End;
2869    llvm::tie(Beg, End) = exampleReport->getRanges();
2870    for ( ; Beg != End; ++Beg)
2871      piece->addRange(*Beg);
2872    D->setEndOfPath(piece);
2873  }
2874
2875  // Get the meta data.
2876  const BugReport::ExtraTextList &Meta = exampleReport->getExtraText();
2877  for (BugReport::ExtraTextList::const_iterator i = Meta.begin(),
2878                                                e = Meta.end(); i != e; ++i) {
2879    D->addMeta(*i);
2880  }
2881
2882  PD.HandlePathDiagnostic(D.take());
2883}
2884
2885void BugReporter::EmitBasicReport(const Decl *DeclWithIssue,
2886                                  StringRef name,
2887                                  StringRef category,
2888                                  StringRef str, PathDiagnosticLocation Loc,
2889                                  SourceRange* RBeg, unsigned NumRanges) {
2890
2891  // 'BT' is owned by BugReporter.
2892  BugType *BT = getBugTypeForName(name, category);
2893  BugReport *R = new BugReport(*BT, str, Loc);
2894  R->setDeclWithIssue(DeclWithIssue);
2895  for ( ; NumRanges > 0 ; --NumRanges, ++RBeg) R->addRange(*RBeg);
2896  emitReport(R);
2897}
2898
2899BugType *BugReporter::getBugTypeForName(StringRef name,
2900                                        StringRef category) {
2901  SmallString<136> fullDesc;
2902  llvm::raw_svector_ostream(fullDesc) << name << ":" << category;
2903  llvm::StringMapEntry<BugType *> &
2904      entry = StrBugTypes.GetOrCreateValue(fullDesc);
2905  BugType *BT = entry.getValue();
2906  if (!BT) {
2907    BT = new BugType(name, category);
2908    entry.setValue(BT);
2909  }
2910  return BT;
2911}
2912