BugReporter.cpp revision aecda966174516c0ac7c05ceb40e88fc99bcf27c 
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
1569static bool
1570GenerateAlternateExtensivePathDiagnostic(PathDiagnostic& PD,
1571                                         PathDiagnosticBuilder &PDB,
1572                                         const ExplodedNode *N,
1573                                         LocationContextMap &LCM,
1574                                      ArrayRef<BugReporterVisitor *> visitors) {
1575
1576  BugReport *report = PDB.getBugReport();
1577  const SourceManager& SM = PDB.getSourceManager();
1578  StackDiagVector CallStack;
1579  InterestingExprs IE;
1580
1581  // Record the last location for a given visited stack frame.
1582  llvm::DenseMap<const StackFrameContext *, PathDiagnosticLocation>
1583    PrevLocMap;
1584
1585  const ExplodedNode *NextNode = N->getFirstPred();
1586  while (NextNode) {
1587    N = NextNode;
1588    NextNode = N->getFirstPred();
1589    ProgramPoint P = N->getLocation();
1590
1591    do {
1592      // Have we encountered an entrance to a call?  It may be
1593      // the case that we have not encountered a matching
1594      // call exit before this point.  This means that the path
1595      // terminated within the call itself.
1596      if (Optional<CallEnter> CE = P.getAs<CallEnter>()) {
1597        // Add an edge to the start of the function.
1598        const StackFrameContext *CalleeLC = CE->getCalleeContext();
1599        PathDiagnosticLocation &PrevLocCallee = PrevLocMap[CalleeLC];
1600        const Decl *D = CalleeLC->getDecl();
1601        addEdgeToPath(PD.getActivePath(), PrevLocCallee,
1602                      PathDiagnosticLocation::createBegin(D, SM),
1603                      CalleeLC);
1604
1605        // Did we visit an entire call?
1606        bool VisitedEntireCall = PD.isWithinCall();
1607        PD.popActivePath();
1608
1609        PathDiagnosticCallPiece *C;
1610        if (VisitedEntireCall) {
1611          PathDiagnosticPiece *P = PD.getActivePath().front().getPtr();
1612          C = cast<PathDiagnosticCallPiece>(P);
1613        } else {
1614          const Decl *Caller = CE->getLocationContext()->getDecl();
1615          C = PathDiagnosticCallPiece::construct(PD.getActivePath(), Caller);
1616
1617          // Since we just transferred the path over to the call piece,
1618          // reset the mapping from active to location context.
1619          assert(PD.getActivePath().size() == 1 &&
1620                 PD.getActivePath().front() == C);
1621          LCM[&PD.getActivePath()] = 0;
1622
1623          // Record the location context mapping for the path within
1624          // the call.
1625          assert(LCM[&C->path] == 0 ||
1626                 LCM[&C->path] == CE->getCalleeContext());
1627          LCM[&C->path] = CE->getCalleeContext();
1628
1629          // If this is the first item in the active path, record
1630          // the new mapping from active path to location context.
1631          const LocationContext *&NewLC = LCM[&PD.getActivePath()];
1632          if (!NewLC) {
1633            NewLC = N->getLocationContext();
1634          }
1635          PDB.LC = NewLC;
1636
1637          // Update the previous location in the active path
1638          // since we just created the call piece lazily.
1639          PrevLocMap[PDB.LC->getCurrentStackFrame()] = C->getLocation();
1640        }
1641        C->setCallee(*CE, SM);
1642
1643        if (!CallStack.empty()) {
1644          assert(CallStack.back().first == C);
1645          CallStack.pop_back();
1646        }
1647        break;
1648      }
1649
1650      // Query the location context here and the previous location
1651      // as processing CallEnter may change the active path.
1652      PDB.LC = N->getLocationContext();
1653
1654      // Get the previous location for the current active
1655      // location context.  All edges will be based on this
1656      // location, and it will be updated in place.
1657      PathDiagnosticLocation &PrevLoc =
1658        PrevLocMap[PDB.LC->getCurrentStackFrame()];
1659
1660      // Record the mapping from the active path to the location
1661      // context.
1662      assert(!LCM[&PD.getActivePath()] ||
1663             LCM[&PD.getActivePath()] == PDB.LC);
1664      LCM[&PD.getActivePath()] = PDB.LC;
1665
1666      // Have we encountered an exit from a function call?
1667      if (Optional<CallExitEnd> CE = P.getAs<CallExitEnd>()) {
1668        const Stmt *S = CE->getCalleeContext()->getCallSite();
1669        // Propagate the interesting symbols accordingly.
1670        if (const Expr *Ex = dyn_cast_or_null<Expr>(S)) {
1671          reversePropagateIntererstingSymbols(*PDB.getBugReport(), IE,
1672                                              N->getState().getPtr(), Ex,
1673                                              N->getLocationContext());
1674        }
1675
1676        // We are descending into a call (backwards).  Construct
1677        // a new call piece to contain the path pieces for that call.
1678        PathDiagnosticCallPiece *C =
1679          PathDiagnosticCallPiece::construct(N, *CE, SM);
1680
1681        // Record the location context for this call piece.
1682        LCM[&C->path] = CE->getCalleeContext();
1683
1684        // Add the edge to the return site.
1685        addEdgeToPath(PD.getActivePath(), PrevLoc, C->callReturn, PDB.LC);
1686        PD.getActivePath().push_front(C);
1687
1688        // Make the contents of the call the active path for now.
1689        PD.pushActivePath(&C->path);
1690        CallStack.push_back(StackDiagPair(C, N));
1691        break;
1692      }
1693
1694      if (Optional<PostStmt> PS = P.getAs<PostStmt>()) {
1695        // For expressions, make sure we propagate the
1696        // interesting symbols correctly.
1697        if (const Expr *Ex = PS->getStmtAs<Expr>())
1698          reversePropagateIntererstingSymbols(*PDB.getBugReport(), IE,
1699                                              N->getState().getPtr(), Ex,
1700                                              N->getLocationContext());
1701
1702        PathDiagnosticLocation L =
1703          PathDiagnosticLocation(PS->getStmt(), SM, PDB.LC);
1704        addEdgeToPath(PD.getActivePath(), PrevLoc, L, PDB.LC);
1705        break;
1706      }
1707
1708      // Block edges.
1709      if (Optional<BlockEdge> BE = P.getAs<BlockEdge>()) {
1710        // Does this represent entering a call?  If so, look at propagating
1711        // interesting symbols across call boundaries.
1712        if (NextNode) {
1713          const LocationContext *CallerCtx = NextNode->getLocationContext();
1714          const LocationContext *CalleeCtx = PDB.LC;
1715          if (CallerCtx != CalleeCtx) {
1716            reversePropagateInterestingSymbols(*PDB.getBugReport(), IE,
1717                                               N->getState().getPtr(),
1718                                               CalleeCtx, CallerCtx);
1719          }
1720        }
1721
1722        // Are we jumping to the head of a loop?  Add a special diagnostic.
1723        if (const Stmt *Loop = BE->getSrc()->getLoopTarget()) {
1724          PathDiagnosticLocation L(Loop, SM, PDB.LC);
1725
1726          PathDiagnosticEventPiece *p =
1727            new PathDiagnosticEventPiece(L, "Looping back to the head "
1728                                            "of the loop");
1729          p->setPrunable(true);
1730
1731          addEdgeToPath(PD.getActivePath(), PrevLoc, p->getLocation(), PDB.LC);
1732          PD.getActivePath().push_front(p);
1733        }
1734
1735        const CFGBlock *BSrc = BE->getSrc();
1736        ParentMap &PM = PDB.getParentMap();
1737
1738        if (const Stmt *Term = BSrc->getTerminator()) {
1739          // Are we jumping past the loop body without ever executing the
1740          // loop (because the condition was false)?
1741          if (isLoop(Term)) {
1742            const Stmt *TermCond = BSrc->getTerminatorCondition();
1743            bool IsInLoopBody =
1744              isInLoopBody(PM, getStmtBeforeCond(PM, TermCond, N), Term);
1745
1746            const char *str = 0;
1747
1748            if (isJumpToFalseBranch(&*BE)) {
1749              if (!IsInLoopBody) {
1750                str = "Loop body executed 0 times";
1751              }
1752            }
1753            else {
1754              str = "Entering loop body";
1755            }
1756
1757            if (str) {
1758              PathDiagnosticLocation L(TermCond, SM, PDB.LC);
1759              PathDiagnosticEventPiece *PE =
1760                new PathDiagnosticEventPiece(L, str);
1761              PE->setPrunable(true);
1762              addEdgeToPath(PD.getActivePath(), PrevLoc,
1763                            PE->getLocation(), PDB.LC);
1764              PD.getActivePath().push_front(PE);
1765            }
1766          }
1767          else if (isa<BreakStmt>(Term) || isa<ContinueStmt>(Term) ||
1768                   isa<GotoStmt>(Term)) {
1769            PathDiagnosticLocation L(Term, SM, PDB.LC);
1770            addEdgeToPath(PD.getActivePath(), PrevLoc, L, PDB.LC);
1771          }
1772        }
1773        break;
1774      }
1775    } while (0);
1776
1777    if (!NextNode)
1778      continue;
1779
1780    // Since the active path may have been updated prior
1781    // to this point, query the active location context now.
1782    PathDiagnosticLocation &PrevLoc =
1783      PrevLocMap[PDB.LC->getCurrentStackFrame()];
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(), PDB.LC);
1791        PD.getActivePath().push_front(p);
1792        updateStackPiecesWithMessage(p, CallStack);
1793      }
1794    }
1795  }
1796
1797  return report->isValid();
1798}
1799
1800const Stmt *getLocStmt(PathDiagnosticLocation L) {
1801  if (!L.isValid())
1802    return 0;
1803  return L.asStmt();
1804}
1805
1806const Stmt *getStmtParent(const Stmt *S, ParentMap &PM) {
1807  if (!S)
1808    return 0;
1809  return PM.getParentIgnoreParens(S);
1810}
1811
1812static bool isConditionForTerminator(const Stmt *S, const Stmt *Cond) {
1813  switch (S->getStmtClass()) {
1814    case Stmt::BinaryOperatorClass: {
1815      const BinaryOperator *BO = cast<BinaryOperator>(S);
1816      if (!BO->isLogicalOp())
1817        return false;
1818      return BO->getLHS() == Cond || BO->getRHS() == Cond;
1819    }
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      const ConditionalOperator *CO = cast<ConditionalOperator>(S);
1838      return CO->getCond() == Cond ||
1839             CO->getLHS() == Cond ||
1840             CO->getRHS() == Cond;
1841    }
1842    case Stmt::ObjCForCollectionStmtClass:
1843      return cast<ObjCForCollectionStmt>(S)->getElement() == Cond;
1844    default:
1845      return false;
1846  }
1847}
1848
1849static bool isIncrementOrInitInForLoop(const Stmt *S, const Stmt *FL) {
1850  const ForStmt *FS = dyn_cast<ForStmt>(FL);
1851  if (!FS)
1852    return false;
1853  return FS->getInc() == S || FS->getInit() == S;
1854}
1855
1856typedef llvm::DenseSet<const PathDiagnosticCallPiece *>
1857        OptimizedCallsSet;
1858
1859static bool optimizeEdges(PathPieces &path, SourceManager &SM,
1860                          OptimizedCallsSet &OCS,
1861                          LocationContextMap &LCM) {
1862  bool hasChanges = false;
1863  const LocationContext *LC = LCM[&path];
1864  assert(LC);
1865  bool isFirst = true;
1866
1867  for (PathPieces::iterator I = path.begin(), E = path.end(); I != E; ) {
1868    bool wasFirst = isFirst;
1869    isFirst = false;
1870
1871    // Optimize subpaths.
1872    if (PathDiagnosticCallPiece *CallI = dyn_cast<PathDiagnosticCallPiece>(*I)){
1873      // Record the fact that a call has been optimized so we only do the
1874      // effort once.
1875      if (!OCS.count(CallI)) {
1876        while (optimizeEdges(CallI->path, SM, OCS, LCM)) {}
1877        OCS.insert(CallI);
1878      }
1879      ++I;
1880      continue;
1881    }
1882
1883    // Pattern match the current piece and its successor.
1884    PathDiagnosticControlFlowPiece *PieceI =
1885      dyn_cast<PathDiagnosticControlFlowPiece>(*I);
1886
1887    if (!PieceI) {
1888      ++I;
1889      continue;
1890    }
1891
1892    ParentMap &PM = LC->getParentMap();
1893    const Stmt *s1Start = getLocStmt(PieceI->getStartLocation());
1894    const Stmt *s1End   = getLocStmt(PieceI->getEndLocation());
1895    const Stmt *level1 = getStmtParent(s1Start, PM);
1896    const Stmt *level2 = getStmtParent(s1End, PM);
1897
1898    if (wasFirst) {
1899      wasFirst = false;
1900
1901      // If the first edge (in isolation) is just a transition from
1902      // an expression to a parent expression then eliminate that edge.
1903      if (level1 && level2 && level2 == PM.getParent(level1)) {
1904        path.erase(I);
1905        // Since we are erasing the current edge at the start of the
1906        // path, just return now so we start analyzing the start of the path
1907        // again.
1908        return true;
1909      }
1910
1911      // If the first edge (in isolation) is a transition from the
1912      // initialization or increment in a for loop then remove it.
1913      if (level1 && isIncrementOrInitInForLoop(s1Start, level1)) {
1914        path.erase(I);
1915        return true;
1916      }
1917    }
1918
1919    PathPieces::iterator NextI = I; ++NextI;
1920    if (NextI == E)
1921      break;
1922
1923    PathDiagnosticControlFlowPiece *PieceNextI =
1924      dyn_cast<PathDiagnosticControlFlowPiece>(*NextI);
1925
1926    if (!PieceNextI) {
1927      ++I;
1928      continue;
1929    }
1930
1931    const Stmt *s2Start = getLocStmt(PieceNextI->getStartLocation());
1932    const Stmt *s2End   = getLocStmt(PieceNextI->getEndLocation());
1933    const Stmt *level3 = getStmtParent(s2Start, PM);
1934    const Stmt *level4 = getStmtParent(s2End, PM);
1935
1936    // Rule I.
1937    //
1938    // If we have two consecutive control edges whose end/begin locations
1939    // are at the same level (e.g. statements or top-level expressions within
1940    // a compound statement, or siblings share a single ancestor expression),
1941    // then merge them if they have no interesting intermediate event.
1942    //
1943    // For example:
1944    //
1945    // (1.1 -> 1.2) -> (1.2 -> 1.3) becomes (1.1 -> 1.3) because the common
1946    // parent is '1'.  Here 'x.y.z' represents the hierarchy of statements.
1947    //
1948    // NOTE: this will be limited later in cases where we add barriers
1949    // to prevent this optimization.
1950    //
1951    if (level1 && level1 == level2 && level1 == level3 && level1 == level4) {
1952      PieceI->setEndLocation(PieceNextI->getEndLocation());
1953      path.erase(NextI);
1954      hasChanges = true;
1955      continue;
1956    }
1957
1958    // Rule II.
1959    //
1960    // Eliminate edges between subexpressions and parent expressions
1961    // when the subexpression is consumed.
1962    //
1963    // NOTE: this will be limited later in cases where we add barriers
1964    // to prevent this optimization.
1965    //
1966    if (s1End && s1End == s2Start && level2) {
1967      if (isIncrementOrInitInForLoop(s1End, level2) ||
1968          (isa<Expr>(s1End) && PM.isConsumedExpr(cast<Expr>(s1End)) &&
1969            !isConditionForTerminator(level2, s1End)))
1970      {
1971        PieceI->setEndLocation(PieceNextI->getEndLocation());
1972        path.erase(NextI);
1973        hasChanges = true;
1974        continue;
1975      }
1976    }
1977
1978    // No changes at this index?  Move to the next one.
1979    ++I;
1980  }
1981
1982  // No changes.
1983  return hasChanges;
1984}
1985
1986static void adjustLoopEdges(PathPieces &pieces, LocationContextMap &LCM,
1987                            SourceManager &SM) {
1988  // Retrieve the parent map for this path.
1989  const LocationContext *LC = LCM[&pieces];
1990  ParentMap &PM = LC->getParentMap();
1991  PathPieces::iterator Prev = pieces.end();
1992  for (PathPieces::iterator I = pieces.begin(), E = pieces.end(); I != E;
1993       Prev = I, ++I) {
1994    // Adjust edges in subpaths.
1995    if (PathDiagnosticCallPiece *Call = dyn_cast<PathDiagnosticCallPiece>(*I)) {
1996      adjustLoopEdges(Call->path, LCM, SM);
1997      continue;
1998    }
1999
2000    PathDiagnosticControlFlowPiece *PieceI =
2001      dyn_cast<PathDiagnosticControlFlowPiece>(*I);
2002
2003    if (!PieceI)
2004      continue;
2005
2006    // We are looking at two edges.  Is the second one incident
2007    // on an expression (or subexpression) of a loop condition.
2008    const Stmt *Dst = getLocStmt(PieceI->getEndLocation());
2009    const Stmt *Src = getLocStmt(PieceI->getStartLocation());
2010
2011    if (!Dst || !Src)
2012      continue;
2013
2014    const ForStmt *FS = 0;
2015    const Stmt *S = Dst;
2016    while (const Stmt *Parent = PM.getParentIgnoreParens(S)) {
2017      FS = dyn_cast<ForStmt>(Parent);
2018      if (FS) {
2019        if (FS->getCond()->IgnoreParens() != S)
2020          FS = 0;
2021        break;
2022      }
2023      S = Parent;
2024    }
2025
2026    // If 'FS' is non-null we have found a match where we have an edge
2027    // incident on the condition of a for statement.
2028    if (!FS)
2029      continue;
2030
2031    // If the current source of the edge is the 'for', then there is nothing
2032    // left to be done.
2033    if (Src == FS)
2034      continue;
2035
2036    // Now look at the previous edge.  We want to know if this was in the same
2037    // "level" as the for statement.
2038    const Stmt *SrcParent = PM.getParentIgnoreParens(Src);
2039    const Stmt *FSParent = PM.getParentIgnoreParens(FS);
2040    if (SrcParent && SrcParent == FSParent) {
2041      PathDiagnosticLocation L(FS, SM, LC);
2042      bool needsEdge = true;
2043
2044      if (Prev != E) {
2045        if (PathDiagnosticControlFlowPiece *P =
2046            dyn_cast<PathDiagnosticControlFlowPiece>(*Prev)) {
2047          const Stmt *PrevSrc = getLocStmt(P->getStartLocation());
2048          if (PrevSrc) {
2049            const Stmt *PrevSrcParent = PM.getParentIgnoreParens(PrevSrc);
2050            if (PrevSrcParent == FSParent) {
2051              P->setEndLocation(L);
2052              needsEdge = false;
2053            }
2054          }
2055        }
2056      }
2057
2058      if (needsEdge) {
2059        PathDiagnosticControlFlowPiece *P =
2060          new PathDiagnosticControlFlowPiece(PieceI->getStartLocation(), L);
2061        pieces.insert(I, P);
2062      }
2063
2064      PieceI->setStartLocation(L);
2065    }
2066  }
2067}
2068
2069//===----------------------------------------------------------------------===//
2070// Methods for BugType and subclasses.
2071//===----------------------------------------------------------------------===//
2072BugType::~BugType() { }
2073
2074void BugType::FlushReports(BugReporter &BR) {}
2075
2076void BuiltinBug::anchor() {}
2077
2078//===----------------------------------------------------------------------===//
2079// Methods for BugReport and subclasses.
2080//===----------------------------------------------------------------------===//
2081
2082void BugReport::NodeResolver::anchor() {}
2083
2084void BugReport::addVisitor(BugReporterVisitor* visitor) {
2085  if (!visitor)
2086    return;
2087
2088  llvm::FoldingSetNodeID ID;
2089  visitor->Profile(ID);
2090  void *InsertPos;
2091
2092  if (CallbacksSet.FindNodeOrInsertPos(ID, InsertPos)) {
2093    delete visitor;
2094    return;
2095  }
2096
2097  CallbacksSet.InsertNode(visitor, InsertPos);
2098  Callbacks.push_back(visitor);
2099  ++ConfigurationChangeToken;
2100}
2101
2102BugReport::~BugReport() {
2103  for (visitor_iterator I = visitor_begin(), E = visitor_end(); I != E; ++I) {
2104    delete *I;
2105  }
2106  while (!interestingSymbols.empty()) {
2107    popInterestingSymbolsAndRegions();
2108  }
2109}
2110
2111const Decl *BugReport::getDeclWithIssue() const {
2112  if (DeclWithIssue)
2113    return DeclWithIssue;
2114
2115  const ExplodedNode *N = getErrorNode();
2116  if (!N)
2117    return 0;
2118
2119  const LocationContext *LC = N->getLocationContext();
2120  return LC->getCurrentStackFrame()->getDecl();
2121}
2122
2123void BugReport::Profile(llvm::FoldingSetNodeID& hash) const {
2124  hash.AddPointer(&BT);
2125  hash.AddString(Description);
2126  PathDiagnosticLocation UL = getUniqueingLocation();
2127  if (UL.isValid()) {
2128    UL.Profile(hash);
2129  } else if (Location.isValid()) {
2130    Location.Profile(hash);
2131  } else {
2132    assert(ErrorNode);
2133    hash.AddPointer(GetCurrentOrPreviousStmt(ErrorNode));
2134  }
2135
2136  for (SmallVectorImpl<SourceRange>::const_iterator I =
2137      Ranges.begin(), E = Ranges.end(); I != E; ++I) {
2138    const SourceRange range = *I;
2139    if (!range.isValid())
2140      continue;
2141    hash.AddInteger(range.getBegin().getRawEncoding());
2142    hash.AddInteger(range.getEnd().getRawEncoding());
2143  }
2144}
2145
2146void BugReport::markInteresting(SymbolRef sym) {
2147  if (!sym)
2148    return;
2149
2150  // If the symbol wasn't already in our set, note a configuration change.
2151  if (getInterestingSymbols().insert(sym).second)
2152    ++ConfigurationChangeToken;
2153
2154  if (const SymbolMetadata *meta = dyn_cast<SymbolMetadata>(sym))
2155    getInterestingRegions().insert(meta->getRegion());
2156}
2157
2158void BugReport::markInteresting(const MemRegion *R) {
2159  if (!R)
2160    return;
2161
2162  // If the base region wasn't already in our set, note a configuration change.
2163  R = R->getBaseRegion();
2164  if (getInterestingRegions().insert(R).second)
2165    ++ConfigurationChangeToken;
2166
2167  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R))
2168    getInterestingSymbols().insert(SR->getSymbol());
2169}
2170
2171void BugReport::markInteresting(SVal V) {
2172  markInteresting(V.getAsRegion());
2173  markInteresting(V.getAsSymbol());
2174}
2175
2176void BugReport::markInteresting(const LocationContext *LC) {
2177  if (!LC)
2178    return;
2179  InterestingLocationContexts.insert(LC);
2180}
2181
2182bool BugReport::isInteresting(SVal V) {
2183  return isInteresting(V.getAsRegion()) || isInteresting(V.getAsSymbol());
2184}
2185
2186bool BugReport::isInteresting(SymbolRef sym) {
2187  if (!sym)
2188    return false;
2189  // We don't currently consider metadata symbols to be interesting
2190  // even if we know their region is interesting. Is that correct behavior?
2191  return getInterestingSymbols().count(sym);
2192}
2193
2194bool BugReport::isInteresting(const MemRegion *R) {
2195  if (!R)
2196    return false;
2197  R = R->getBaseRegion();
2198  bool b = getInterestingRegions().count(R);
2199  if (b)
2200    return true;
2201  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R))
2202    return getInterestingSymbols().count(SR->getSymbol());
2203  return false;
2204}
2205
2206bool BugReport::isInteresting(const LocationContext *LC) {
2207  if (!LC)
2208    return false;
2209  return InterestingLocationContexts.count(LC);
2210}
2211
2212void BugReport::lazyInitializeInterestingSets() {
2213  if (interestingSymbols.empty()) {
2214    interestingSymbols.push_back(new Symbols());
2215    interestingRegions.push_back(new Regions());
2216  }
2217}
2218
2219BugReport::Symbols &BugReport::getInterestingSymbols() {
2220  lazyInitializeInterestingSets();
2221  return *interestingSymbols.back();
2222}
2223
2224BugReport::Regions &BugReport::getInterestingRegions() {
2225  lazyInitializeInterestingSets();
2226  return *interestingRegions.back();
2227}
2228
2229void BugReport::pushInterestingSymbolsAndRegions() {
2230  interestingSymbols.push_back(new Symbols(getInterestingSymbols()));
2231  interestingRegions.push_back(new Regions(getInterestingRegions()));
2232}
2233
2234void BugReport::popInterestingSymbolsAndRegions() {
2235  delete interestingSymbols.back();
2236  interestingSymbols.pop_back();
2237  delete interestingRegions.back();
2238  interestingRegions.pop_back();
2239}
2240
2241const Stmt *BugReport::getStmt() const {
2242  if (!ErrorNode)
2243    return 0;
2244
2245  ProgramPoint ProgP = ErrorNode->getLocation();
2246  const Stmt *S = NULL;
2247
2248  if (Optional<BlockEntrance> BE = ProgP.getAs<BlockEntrance>()) {
2249    CFGBlock &Exit = ProgP.getLocationContext()->getCFG()->getExit();
2250    if (BE->getBlock() == &Exit)
2251      S = GetPreviousStmt(ErrorNode);
2252  }
2253  if (!S)
2254    S = PathDiagnosticLocation::getStmt(ErrorNode);
2255
2256  return S;
2257}
2258
2259std::pair<BugReport::ranges_iterator, BugReport::ranges_iterator>
2260BugReport::getRanges() {
2261    // If no custom ranges, add the range of the statement corresponding to
2262    // the error node.
2263    if (Ranges.empty()) {
2264      if (const Expr *E = dyn_cast_or_null<Expr>(getStmt()))
2265        addRange(E->getSourceRange());
2266      else
2267        return std::make_pair(ranges_iterator(), ranges_iterator());
2268    }
2269
2270    // User-specified absence of range info.
2271    if (Ranges.size() == 1 && !Ranges.begin()->isValid())
2272      return std::make_pair(ranges_iterator(), ranges_iterator());
2273
2274    return std::make_pair(Ranges.begin(), Ranges.end());
2275}
2276
2277PathDiagnosticLocation BugReport::getLocation(const SourceManager &SM) const {
2278  if (ErrorNode) {
2279    assert(!Location.isValid() &&
2280     "Either Location or ErrorNode should be specified but not both.");
2281    return PathDiagnosticLocation::createEndOfPath(ErrorNode, SM);
2282  } else {
2283    assert(Location.isValid());
2284    return Location;
2285  }
2286
2287  return PathDiagnosticLocation();
2288}
2289
2290//===----------------------------------------------------------------------===//
2291// Methods for BugReporter and subclasses.
2292//===----------------------------------------------------------------------===//
2293
2294BugReportEquivClass::~BugReportEquivClass() { }
2295GRBugReporter::~GRBugReporter() { }
2296BugReporterData::~BugReporterData() {}
2297
2298ExplodedGraph &GRBugReporter::getGraph() { return Eng.getGraph(); }
2299
2300ProgramStateManager&
2301GRBugReporter::getStateManager() { return Eng.getStateManager(); }
2302
2303BugReporter::~BugReporter() {
2304  FlushReports();
2305
2306  // Free the bug reports we are tracking.
2307  typedef std::vector<BugReportEquivClass *> ContTy;
2308  for (ContTy::iterator I = EQClassesVector.begin(), E = EQClassesVector.end();
2309       I != E; ++I) {
2310    delete *I;
2311  }
2312}
2313
2314void BugReporter::FlushReports() {
2315  if (BugTypes.isEmpty())
2316    return;
2317
2318  // First flush the warnings for each BugType.  This may end up creating new
2319  // warnings and new BugTypes.
2320  // FIXME: Only NSErrorChecker needs BugType's FlushReports.
2321  // Turn NSErrorChecker into a proper checker and remove this.
2322  SmallVector<const BugType*, 16> bugTypes;
2323  for (BugTypesTy::iterator I=BugTypes.begin(), E=BugTypes.end(); I!=E; ++I)
2324    bugTypes.push_back(*I);
2325  for (SmallVector<const BugType*, 16>::iterator
2326         I = bugTypes.begin(), E = bugTypes.end(); I != E; ++I)
2327    const_cast<BugType*>(*I)->FlushReports(*this);
2328
2329  // We need to flush reports in deterministic order to ensure the order
2330  // of the reports is consistent between runs.
2331  typedef std::vector<BugReportEquivClass *> ContVecTy;
2332  for (ContVecTy::iterator EI=EQClassesVector.begin(), EE=EQClassesVector.end();
2333       EI != EE; ++EI){
2334    BugReportEquivClass& EQ = **EI;
2335    FlushReport(EQ);
2336  }
2337
2338  // BugReporter owns and deletes only BugTypes created implicitly through
2339  // EmitBasicReport.
2340  // FIXME: There are leaks from checkers that assume that the BugTypes they
2341  // create will be destroyed by the BugReporter.
2342  for (llvm::StringMap<BugType*>::iterator
2343         I = StrBugTypes.begin(), E = StrBugTypes.end(); I != E; ++I)
2344    delete I->second;
2345
2346  // Remove all references to the BugType objects.
2347  BugTypes = F.getEmptySet();
2348}
2349
2350//===----------------------------------------------------------------------===//
2351// PathDiagnostics generation.
2352//===----------------------------------------------------------------------===//
2353
2354namespace {
2355/// A wrapper around a report graph, which contains only a single path, and its
2356/// node maps.
2357class ReportGraph {
2358public:
2359  InterExplodedGraphMap BackMap;
2360  OwningPtr<ExplodedGraph> Graph;
2361  const ExplodedNode *ErrorNode;
2362  size_t Index;
2363};
2364
2365/// A wrapper around a trimmed graph and its node maps.
2366class TrimmedGraph {
2367  InterExplodedGraphMap InverseMap;
2368
2369  typedef llvm::DenseMap<const ExplodedNode *, unsigned> PriorityMapTy;
2370  PriorityMapTy PriorityMap;
2371
2372  typedef std::pair<const ExplodedNode *, size_t> NodeIndexPair;
2373  SmallVector<NodeIndexPair, 32> ReportNodes;
2374
2375  OwningPtr<ExplodedGraph> G;
2376
2377  /// A helper class for sorting ExplodedNodes by priority.
2378  template <bool Descending>
2379  class PriorityCompare {
2380    const PriorityMapTy &PriorityMap;
2381
2382  public:
2383    PriorityCompare(const PriorityMapTy &M) : PriorityMap(M) {}
2384
2385    bool operator()(const ExplodedNode *LHS, const ExplodedNode *RHS) const {
2386      PriorityMapTy::const_iterator LI = PriorityMap.find(LHS);
2387      PriorityMapTy::const_iterator RI = PriorityMap.find(RHS);
2388      PriorityMapTy::const_iterator E = PriorityMap.end();
2389
2390      if (LI == E)
2391        return Descending;
2392      if (RI == E)
2393        return !Descending;
2394
2395      return Descending ? LI->second > RI->second
2396                        : LI->second < RI->second;
2397    }
2398
2399    bool operator()(const NodeIndexPair &LHS, const NodeIndexPair &RHS) const {
2400      return (*this)(LHS.first, RHS.first);
2401    }
2402  };
2403
2404public:
2405  TrimmedGraph(const ExplodedGraph *OriginalGraph,
2406               ArrayRef<const ExplodedNode *> Nodes);
2407
2408  bool popNextReportGraph(ReportGraph &GraphWrapper);
2409};
2410}
2411
2412TrimmedGraph::TrimmedGraph(const ExplodedGraph *OriginalGraph,
2413                           ArrayRef<const ExplodedNode *> Nodes) {
2414  // The trimmed graph is created in the body of the constructor to ensure
2415  // that the DenseMaps have been initialized already.
2416  InterExplodedGraphMap ForwardMap;
2417  G.reset(OriginalGraph->trim(Nodes, &ForwardMap, &InverseMap));
2418
2419  // Find the (first) error node in the trimmed graph.  We just need to consult
2420  // the node map which maps from nodes in the original graph to nodes
2421  // in the new graph.
2422  llvm::SmallPtrSet<const ExplodedNode *, 32> RemainingNodes;
2423
2424  for (unsigned i = 0, count = Nodes.size(); i < count; ++i) {
2425    if (const ExplodedNode *NewNode = ForwardMap.lookup(Nodes[i])) {
2426      ReportNodes.push_back(std::make_pair(NewNode, i));
2427      RemainingNodes.insert(NewNode);
2428    }
2429  }
2430
2431  assert(!RemainingNodes.empty() && "No error node found in the trimmed graph");
2432
2433  // Perform a forward BFS to find all the shortest paths.
2434  std::queue<const ExplodedNode *> WS;
2435
2436  assert(G->num_roots() == 1);
2437  WS.push(*G->roots_begin());
2438  unsigned Priority = 0;
2439
2440  while (!WS.empty()) {
2441    const ExplodedNode *Node = WS.front();
2442    WS.pop();
2443
2444    PriorityMapTy::iterator PriorityEntry;
2445    bool IsNew;
2446    llvm::tie(PriorityEntry, IsNew) =
2447      PriorityMap.insert(std::make_pair(Node, Priority));
2448    ++Priority;
2449
2450    if (!IsNew) {
2451      assert(PriorityEntry->second <= Priority);
2452      continue;
2453    }
2454
2455    if (RemainingNodes.erase(Node))
2456      if (RemainingNodes.empty())
2457        break;
2458
2459    for (ExplodedNode::const_pred_iterator I = Node->succ_begin(),
2460                                           E = Node->succ_end();
2461         I != E; ++I)
2462      WS.push(*I);
2463  }
2464
2465  // Sort the error paths from longest to shortest.
2466  std::sort(ReportNodes.begin(), ReportNodes.end(),
2467            PriorityCompare<true>(PriorityMap));
2468}
2469
2470bool TrimmedGraph::popNextReportGraph(ReportGraph &GraphWrapper) {
2471  if (ReportNodes.empty())
2472    return false;
2473
2474  const ExplodedNode *OrigN;
2475  llvm::tie(OrigN, GraphWrapper.Index) = ReportNodes.pop_back_val();
2476  assert(PriorityMap.find(OrigN) != PriorityMap.end() &&
2477         "error node not accessible from root");
2478
2479  // Create a new graph with a single path.  This is the graph
2480  // that will be returned to the caller.
2481  ExplodedGraph *GNew = new ExplodedGraph();
2482  GraphWrapper.Graph.reset(GNew);
2483  GraphWrapper.BackMap.clear();
2484
2485  // Now walk from the error node up the BFS path, always taking the
2486  // predeccessor with the lowest number.
2487  ExplodedNode *Succ = 0;
2488  while (true) {
2489    // Create the equivalent node in the new graph with the same state
2490    // and location.
2491    ExplodedNode *NewN = GNew->getNode(OrigN->getLocation(), OrigN->getState(),
2492                                       OrigN->isSink());
2493
2494    // Store the mapping to the original node.
2495    InterExplodedGraphMap::const_iterator IMitr = InverseMap.find(OrigN);
2496    assert(IMitr != InverseMap.end() && "No mapping to original node.");
2497    GraphWrapper.BackMap[NewN] = IMitr->second;
2498
2499    // Link up the new node with the previous node.
2500    if (Succ)
2501      Succ->addPredecessor(NewN, *GNew);
2502    else
2503      GraphWrapper.ErrorNode = NewN;
2504
2505    Succ = NewN;
2506
2507    // Are we at the final node?
2508    if (OrigN->pred_empty()) {
2509      GNew->addRoot(NewN);
2510      break;
2511    }
2512
2513    // Find the next predeccessor node.  We choose the node that is marked
2514    // with the lowest BFS number.
2515    OrigN = *std::min_element(OrigN->pred_begin(), OrigN->pred_end(),
2516                          PriorityCompare<false>(PriorityMap));
2517  }
2518
2519  return true;
2520}
2521
2522
2523/// CompactPathDiagnostic - This function postprocesses a PathDiagnostic object
2524///  and collapses PathDiagosticPieces that are expanded by macros.
2525static void CompactPathDiagnostic(PathPieces &path, const SourceManager& SM) {
2526  typedef std::vector<std::pair<IntrusiveRefCntPtr<PathDiagnosticMacroPiece>,
2527                                SourceLocation> > MacroStackTy;
2528
2529  typedef std::vector<IntrusiveRefCntPtr<PathDiagnosticPiece> >
2530          PiecesTy;
2531
2532  MacroStackTy MacroStack;
2533  PiecesTy Pieces;
2534
2535  for (PathPieces::const_iterator I = path.begin(), E = path.end();
2536       I!=E; ++I) {
2537
2538    PathDiagnosticPiece *piece = I->getPtr();
2539
2540    // Recursively compact calls.
2541    if (PathDiagnosticCallPiece *call=dyn_cast<PathDiagnosticCallPiece>(piece)){
2542      CompactPathDiagnostic(call->path, SM);
2543    }
2544
2545    // Get the location of the PathDiagnosticPiece.
2546    const FullSourceLoc Loc = piece->getLocation().asLocation();
2547
2548    // Determine the instantiation location, which is the location we group
2549    // related PathDiagnosticPieces.
2550    SourceLocation InstantiationLoc = Loc.isMacroID() ?
2551                                      SM.getExpansionLoc(Loc) :
2552                                      SourceLocation();
2553
2554    if (Loc.isFileID()) {
2555      MacroStack.clear();
2556      Pieces.push_back(piece);
2557      continue;
2558    }
2559
2560    assert(Loc.isMacroID());
2561
2562    // Is the PathDiagnosticPiece within the same macro group?
2563    if (!MacroStack.empty() && InstantiationLoc == MacroStack.back().second) {
2564      MacroStack.back().first->subPieces.push_back(piece);
2565      continue;
2566    }
2567
2568    // We aren't in the same group.  Are we descending into a new macro
2569    // or are part of an old one?
2570    IntrusiveRefCntPtr<PathDiagnosticMacroPiece> MacroGroup;
2571
2572    SourceLocation ParentInstantiationLoc = InstantiationLoc.isMacroID() ?
2573                                          SM.getExpansionLoc(Loc) :
2574                                          SourceLocation();
2575
2576    // Walk the entire macro stack.
2577    while (!MacroStack.empty()) {
2578      if (InstantiationLoc == MacroStack.back().second) {
2579        MacroGroup = MacroStack.back().first;
2580        break;
2581      }
2582
2583      if (ParentInstantiationLoc == MacroStack.back().second) {
2584        MacroGroup = MacroStack.back().first;
2585        break;
2586      }
2587
2588      MacroStack.pop_back();
2589    }
2590
2591    if (!MacroGroup || ParentInstantiationLoc == MacroStack.back().second) {
2592      // Create a new macro group and add it to the stack.
2593      PathDiagnosticMacroPiece *NewGroup =
2594        new PathDiagnosticMacroPiece(
2595          PathDiagnosticLocation::createSingleLocation(piece->getLocation()));
2596
2597      if (MacroGroup)
2598        MacroGroup->subPieces.push_back(NewGroup);
2599      else {
2600        assert(InstantiationLoc.isFileID());
2601        Pieces.push_back(NewGroup);
2602      }
2603
2604      MacroGroup = NewGroup;
2605      MacroStack.push_back(std::make_pair(MacroGroup, InstantiationLoc));
2606    }
2607
2608    // Finally, add the PathDiagnosticPiece to the group.
2609    MacroGroup->subPieces.push_back(piece);
2610  }
2611
2612  // Now take the pieces and construct a new PathDiagnostic.
2613  path.clear();
2614
2615  for (PiecesTy::iterator I=Pieces.begin(), E=Pieces.end(); I!=E; ++I)
2616    path.push_back(*I);
2617}
2618
2619bool GRBugReporter::generatePathDiagnostic(PathDiagnostic& PD,
2620                                           PathDiagnosticConsumer &PC,
2621                                           ArrayRef<BugReport *> &bugReports) {
2622  assert(!bugReports.empty());
2623
2624  bool HasValid = false;
2625  bool HasInvalid = false;
2626  SmallVector<const ExplodedNode *, 32> errorNodes;
2627  for (ArrayRef<BugReport*>::iterator I = bugReports.begin(),
2628                                      E = bugReports.end(); I != E; ++I) {
2629    if ((*I)->isValid()) {
2630      HasValid = true;
2631      errorNodes.push_back((*I)->getErrorNode());
2632    } else {
2633      // Keep the errorNodes list in sync with the bugReports list.
2634      HasInvalid = true;
2635      errorNodes.push_back(0);
2636    }
2637  }
2638
2639  // If all the reports have been marked invalid by a previous path generation,
2640  // we're done.
2641  if (!HasValid)
2642    return false;
2643
2644  typedef PathDiagnosticConsumer::PathGenerationScheme PathGenerationScheme;
2645  PathGenerationScheme ActiveScheme = PC.getGenerationScheme();
2646
2647  if (ActiveScheme == PathDiagnosticConsumer::Extensive) {
2648    AnalyzerOptions &options = getEngine().getAnalysisManager().options;
2649    if (options.getBooleanOption("path-diagnostics-alternate", false)) {
2650      ActiveScheme = PathDiagnosticConsumer::AlternateExtensive;
2651    }
2652  }
2653
2654  TrimmedGraph TrimG(&getGraph(), errorNodes);
2655  ReportGraph ErrorGraph;
2656
2657  while (TrimG.popNextReportGraph(ErrorGraph)) {
2658    // Find the BugReport with the original location.
2659    assert(ErrorGraph.Index < bugReports.size());
2660    BugReport *R = bugReports[ErrorGraph.Index];
2661    assert(R && "No original report found for sliced graph.");
2662    assert(R->isValid() && "Report selected by trimmed graph marked invalid.");
2663
2664    // Start building the path diagnostic...
2665    PathDiagnosticBuilder PDB(*this, R, ErrorGraph.BackMap, &PC);
2666    const ExplodedNode *N = ErrorGraph.ErrorNode;
2667
2668    // Register additional node visitors.
2669    R->addVisitor(new NilReceiverBRVisitor());
2670    R->addVisitor(new ConditionBRVisitor());
2671    R->addVisitor(new LikelyFalsePositiveSuppressionBRVisitor());
2672
2673    BugReport::VisitorList visitors;
2674    unsigned origReportConfigToken, finalReportConfigToken;
2675    LocationContextMap LCM;
2676
2677    // While generating diagnostics, it's possible the visitors will decide
2678    // new symbols and regions are interesting, or add other visitors based on
2679    // the information they find. If they do, we need to regenerate the path
2680    // based on our new report configuration.
2681    do {
2682      // Get a clean copy of all the visitors.
2683      for (BugReport::visitor_iterator I = R->visitor_begin(),
2684                                       E = R->visitor_end(); I != E; ++I)
2685        visitors.push_back((*I)->clone());
2686
2687      // Clear out the active path from any previous work.
2688      PD.resetPath();
2689      origReportConfigToken = R->getConfigurationChangeToken();
2690
2691      // Generate the very last diagnostic piece - the piece is visible before
2692      // the trace is expanded.
2693      PathDiagnosticPiece *LastPiece = 0;
2694      for (BugReport::visitor_iterator I = visitors.begin(), E = visitors.end();
2695          I != E; ++I) {
2696        if (PathDiagnosticPiece *Piece = (*I)->getEndPath(PDB, N, *R)) {
2697          assert (!LastPiece &&
2698              "There can only be one final piece in a diagnostic.");
2699          LastPiece = Piece;
2700        }
2701      }
2702
2703      if (ActiveScheme != PathDiagnosticConsumer::None) {
2704        if (!LastPiece)
2705          LastPiece = BugReporterVisitor::getDefaultEndPath(PDB, N, *R);
2706        assert(LastPiece);
2707        PD.setEndOfPath(LastPiece);
2708      }
2709
2710      // Make sure we get a clean location context map so we don't
2711      // hold onto old mappings.
2712      LCM.clear();
2713
2714      switch (ActiveScheme) {
2715      case PathDiagnosticConsumer::AlternateExtensive:
2716        GenerateAlternateExtensivePathDiagnostic(PD, PDB, N, LCM, visitors);
2717        break;
2718      case PathDiagnosticConsumer::Extensive:
2719        GenerateExtensivePathDiagnostic(PD, PDB, N, LCM, visitors);
2720        break;
2721      case PathDiagnosticConsumer::Minimal:
2722        GenerateMinimalPathDiagnostic(PD, PDB, N, LCM, visitors);
2723        break;
2724      case PathDiagnosticConsumer::None:
2725        GenerateVisitorsOnlyPathDiagnostic(PD, PDB, N, visitors);
2726        break;
2727      }
2728
2729      // Clean up the visitors we used.
2730      llvm::DeleteContainerPointers(visitors);
2731
2732      // Did anything change while generating this path?
2733      finalReportConfigToken = R->getConfigurationChangeToken();
2734    } while (finalReportConfigToken != origReportConfigToken);
2735
2736    if (!R->isValid())
2737      continue;
2738
2739    // Finally, prune the diagnostic path of uninteresting stuff.
2740    if (!PD.path.empty()) {
2741      // Remove messages that are basically the same.
2742      removeRedundantMsgs(PD.getMutablePieces());
2743
2744      if (R->shouldPrunePath() &&
2745          getEngine().getAnalysisManager().options.shouldPrunePaths()) {
2746        bool stillHasNotes = removeUnneededCalls(PD.getMutablePieces(), R, LCM);
2747        assert(stillHasNotes);
2748        (void)stillHasNotes;
2749      }
2750
2751      adjustCallLocations(PD.getMutablePieces());
2752
2753      if (ActiveScheme == PathDiagnosticConsumer::AlternateExtensive) {
2754        SourceManager &SM = getSourceManager();
2755
2756        // Reduce the number of edges from a very conservative set
2757        // to an aesthetically pleasing subset that conveys the
2758        // necessary information.
2759        OptimizedCallsSet OCS;
2760        while (optimizeEdges(PD.getMutablePieces(), SM, OCS, LCM)) {}
2761
2762        // Adjust edges into loop conditions to make them more uniform
2763        // and aesthetically pleasing.
2764        adjustLoopEdges(PD.getMutablePieces(), LCM, SM);
2765      }
2766    }
2767
2768    // We found a report and didn't suppress it.
2769    return true;
2770  }
2771
2772  // We suppressed all the reports in this equivalence class.
2773  assert(!HasInvalid && "Inconsistent suppression");
2774  (void)HasInvalid;
2775  return false;
2776}
2777
2778void BugReporter::Register(BugType *BT) {
2779  BugTypes = F.add(BugTypes, BT);
2780}
2781
2782void BugReporter::emitReport(BugReport* R) {
2783  // Compute the bug report's hash to determine its equivalence class.
2784  llvm::FoldingSetNodeID ID;
2785  R->Profile(ID);
2786
2787  // Lookup the equivance class.  If there isn't one, create it.
2788  BugType& BT = R->getBugType();
2789  Register(&BT);
2790  void *InsertPos;
2791  BugReportEquivClass* EQ = EQClasses.FindNodeOrInsertPos(ID, InsertPos);
2792
2793  if (!EQ) {
2794    EQ = new BugReportEquivClass(R);
2795    EQClasses.InsertNode(EQ, InsertPos);
2796    EQClassesVector.push_back(EQ);
2797  }
2798  else
2799    EQ->AddReport(R);
2800}
2801
2802
2803//===----------------------------------------------------------------------===//
2804// Emitting reports in equivalence classes.
2805//===----------------------------------------------------------------------===//
2806
2807namespace {
2808struct FRIEC_WLItem {
2809  const ExplodedNode *N;
2810  ExplodedNode::const_succ_iterator I, E;
2811
2812  FRIEC_WLItem(const ExplodedNode *n)
2813  : N(n), I(N->succ_begin()), E(N->succ_end()) {}
2814};
2815}
2816
2817static BugReport *
2818FindReportInEquivalenceClass(BugReportEquivClass& EQ,
2819                             SmallVectorImpl<BugReport*> &bugReports) {
2820
2821  BugReportEquivClass::iterator I = EQ.begin(), E = EQ.end();
2822  assert(I != E);
2823  BugType& BT = I->getBugType();
2824
2825  // If we don't need to suppress any of the nodes because they are
2826  // post-dominated by a sink, simply add all the nodes in the equivalence class
2827  // to 'Nodes'.  Any of the reports will serve as a "representative" report.
2828  if (!BT.isSuppressOnSink()) {
2829    BugReport *R = I;
2830    for (BugReportEquivClass::iterator I=EQ.begin(), E=EQ.end(); I!=E; ++I) {
2831      const ExplodedNode *N = I->getErrorNode();
2832      if (N) {
2833        R = I;
2834        bugReports.push_back(R);
2835      }
2836    }
2837    return R;
2838  }
2839
2840  // For bug reports that should be suppressed when all paths are post-dominated
2841  // by a sink node, iterate through the reports in the equivalence class
2842  // until we find one that isn't post-dominated (if one exists).  We use a
2843  // DFS traversal of the ExplodedGraph to find a non-sink node.  We could write
2844  // this as a recursive function, but we don't want to risk blowing out the
2845  // stack for very long paths.
2846  BugReport *exampleReport = 0;
2847
2848  for (; I != E; ++I) {
2849    const ExplodedNode *errorNode = I->getErrorNode();
2850
2851    if (!errorNode)
2852      continue;
2853    if (errorNode->isSink()) {
2854      llvm_unreachable(
2855           "BugType::isSuppressSink() should not be 'true' for sink end nodes");
2856    }
2857    // No successors?  By definition this nodes isn't post-dominated by a sink.
2858    if (errorNode->succ_empty()) {
2859      bugReports.push_back(I);
2860      if (!exampleReport)
2861        exampleReport = I;
2862      continue;
2863    }
2864
2865    // At this point we know that 'N' is not a sink and it has at least one
2866    // successor.  Use a DFS worklist to find a non-sink end-of-path node.
2867    typedef FRIEC_WLItem WLItem;
2868    typedef SmallVector<WLItem, 10> DFSWorkList;
2869    llvm::DenseMap<const ExplodedNode *, unsigned> Visited;
2870
2871    DFSWorkList WL;
2872    WL.push_back(errorNode);
2873    Visited[errorNode] = 1;
2874
2875    while (!WL.empty()) {
2876      WLItem &WI = WL.back();
2877      assert(!WI.N->succ_empty());
2878
2879      for (; WI.I != WI.E; ++WI.I) {
2880        const ExplodedNode *Succ = *WI.I;
2881        // End-of-path node?
2882        if (Succ->succ_empty()) {
2883          // If we found an end-of-path node that is not a sink.
2884          if (!Succ->isSink()) {
2885            bugReports.push_back(I);
2886            if (!exampleReport)
2887              exampleReport = I;
2888            WL.clear();
2889            break;
2890          }
2891          // Found a sink?  Continue on to the next successor.
2892          continue;
2893        }
2894        // Mark the successor as visited.  If it hasn't been explored,
2895        // enqueue it to the DFS worklist.
2896        unsigned &mark = Visited[Succ];
2897        if (!mark) {
2898          mark = 1;
2899          WL.push_back(Succ);
2900          break;
2901        }
2902      }
2903
2904      // The worklist may have been cleared at this point.  First
2905      // check if it is empty before checking the last item.
2906      if (!WL.empty() && &WL.back() == &WI)
2907        WL.pop_back();
2908    }
2909  }
2910
2911  // ExampleReport will be NULL if all the nodes in the equivalence class
2912  // were post-dominated by sinks.
2913  return exampleReport;
2914}
2915
2916void BugReporter::FlushReport(BugReportEquivClass& EQ) {
2917  SmallVector<BugReport*, 10> bugReports;
2918  BugReport *exampleReport = FindReportInEquivalenceClass(EQ, bugReports);
2919  if (exampleReport) {
2920    const PathDiagnosticConsumers &C = getPathDiagnosticConsumers();
2921    for (PathDiagnosticConsumers::const_iterator I=C.begin(),
2922                                                 E=C.end(); I != E; ++I) {
2923      FlushReport(exampleReport, **I, bugReports);
2924    }
2925  }
2926}
2927
2928void BugReporter::FlushReport(BugReport *exampleReport,
2929                              PathDiagnosticConsumer &PD,
2930                              ArrayRef<BugReport*> bugReports) {
2931
2932  // FIXME: Make sure we use the 'R' for the path that was actually used.
2933  // Probably doesn't make a difference in practice.
2934  BugType& BT = exampleReport->getBugType();
2935
2936  OwningPtr<PathDiagnostic>
2937    D(new PathDiagnostic(exampleReport->getDeclWithIssue(),
2938                         exampleReport->getBugType().getName(),
2939                         exampleReport->getDescription(),
2940                         exampleReport->getShortDescription(/*Fallback=*/false),
2941                         BT.getCategory(),
2942                         exampleReport->getUniqueingLocation(),
2943                         exampleReport->getUniqueingDecl()));
2944
2945  MaxBugClassSize = std::max(bugReports.size(),
2946                             static_cast<size_t>(MaxBugClassSize));
2947
2948  // Generate the full path diagnostic, using the generation scheme
2949  // specified by the PathDiagnosticConsumer. Note that we have to generate
2950  // path diagnostics even for consumers which do not support paths, because
2951  // the BugReporterVisitors may mark this bug as a false positive.
2952  if (!bugReports.empty())
2953    if (!generatePathDiagnostic(*D.get(), PD, bugReports))
2954      return;
2955
2956  MaxValidBugClassSize = std::max(bugReports.size(),
2957                                  static_cast<size_t>(MaxValidBugClassSize));
2958
2959  // If the path is empty, generate a single step path with the location
2960  // of the issue.
2961  if (D->path.empty()) {
2962    PathDiagnosticLocation L = exampleReport->getLocation(getSourceManager());
2963    PathDiagnosticPiece *piece =
2964      new PathDiagnosticEventPiece(L, exampleReport->getDescription());
2965    BugReport::ranges_iterator Beg, End;
2966    llvm::tie(Beg, End) = exampleReport->getRanges();
2967    for ( ; Beg != End; ++Beg)
2968      piece->addRange(*Beg);
2969    D->setEndOfPath(piece);
2970  }
2971
2972  // Get the meta data.
2973  const BugReport::ExtraTextList &Meta = exampleReport->getExtraText();
2974  for (BugReport::ExtraTextList::const_iterator i = Meta.begin(),
2975                                                e = Meta.end(); i != e; ++i) {
2976    D->addMeta(*i);
2977  }
2978
2979  PD.HandlePathDiagnostic(D.take());
2980}
2981
2982void BugReporter::EmitBasicReport(const Decl *DeclWithIssue,
2983                                  StringRef name,
2984                                  StringRef category,
2985                                  StringRef str, PathDiagnosticLocation Loc,
2986                                  SourceRange* RBeg, unsigned NumRanges) {
2987
2988  // 'BT' is owned by BugReporter.
2989  BugType *BT = getBugTypeForName(name, category);
2990  BugReport *R = new BugReport(*BT, str, Loc);
2991  R->setDeclWithIssue(DeclWithIssue);
2992  for ( ; NumRanges > 0 ; --NumRanges, ++RBeg) R->addRange(*RBeg);
2993  emitReport(R);
2994}
2995
2996BugType *BugReporter::getBugTypeForName(StringRef name,
2997                                        StringRef category) {
2998  SmallString<136> fullDesc;
2999  llvm::raw_svector_ostream(fullDesc) << name << ":" << category;
3000  llvm::StringMapEntry<BugType *> &
3001      entry = StrBugTypes.GetOrCreateValue(fullDesc);
3002  BugType *BT = entry.getValue();
3003  if (!BT) {
3004    BT = new BugType(name, category);
3005    entry.setValue(BT);
3006  }
3007  return BT;
3008}
3009