BugReporter.cpp revision e644ed5308ab22e4bcb5f821fe7ea9dae324a0a8 
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
1264/// Return true if the terminator is a loop and the destination is the
1265/// false branch.
1266static bool isLoopJumpPastBody(const Stmt *Term, const BlockEdge *BE) {
1267  switch (Term->getStmtClass()) {
1268    case Stmt::ForStmtClass:
1269    case Stmt::WhileStmtClass:
1270    case Stmt::ObjCForCollectionStmtClass:
1271      break;
1272    default:
1273      // Note that we intentionally do not include do..while here.
1274      return false;
1275  }
1276
1277  // Did we take the false branch?
1278  const CFGBlock *Src = BE->getSrc();
1279  assert(Src->succ_size() == 2);
1280  return (*(Src->succ_begin()+1) == BE->getDst());
1281}
1282
1283static bool isContainedByStmt(ParentMap &PM, const Stmt *S, const Stmt *SubS) {
1284  while (SubS) {
1285    if (SubS == S)
1286      return true;
1287    SubS = PM.getParent(SubS);
1288  }
1289  return false;
1290}
1291
1292static const Stmt *getStmtBeforeCond(ParentMap &PM, const Stmt *Term,
1293                                     const ExplodedNode *N) {
1294  while (N) {
1295    Optional<StmtPoint> SP = N->getLocation().getAs<StmtPoint>();
1296    if (SP) {
1297      const Stmt *S = SP->getStmt();
1298      if (!isContainedByStmt(PM, Term, S))
1299        return S;
1300    }
1301    N = N->getFirstPred();
1302  }
1303  return 0;
1304}
1305
1306static bool isInLoopBody(ParentMap &PM, const Stmt *S, const Stmt *Term) {
1307  const Stmt *LoopBody = 0;
1308  switch (Term->getStmtClass()) {
1309    case Stmt::ForStmtClass: {
1310      const ForStmt *FS = cast<ForStmt>(Term);
1311      if (isContainedByStmt(PM, FS->getInc(), S))
1312        return true;
1313      LoopBody = FS->getBody();
1314      break;
1315    }
1316    case Stmt::ObjCForCollectionStmtClass: {
1317      const ObjCForCollectionStmt *FC = cast<ObjCForCollectionStmt>(Term);
1318      LoopBody = FC->getBody();
1319      break;
1320    }
1321    case Stmt::WhileStmtClass:
1322      LoopBody = cast<WhileStmt>(Term)->getBody();
1323      break;
1324    default:
1325      return false;
1326  }
1327  return isContainedByStmt(PM, LoopBody, S);
1328}
1329
1330//===----------------------------------------------------------------------===//
1331// Top-level logic for generating extensive path diagnostics.
1332//===----------------------------------------------------------------------===//
1333
1334static bool GenerateExtensivePathDiagnostic(PathDiagnostic& PD,
1335                                            PathDiagnosticBuilder &PDB,
1336                                            const ExplodedNode *N,
1337                                            LocationContextMap &LCM,
1338                                      ArrayRef<BugReporterVisitor *> visitors) {
1339  EdgeBuilder EB(PD, PDB);
1340  const SourceManager& SM = PDB.getSourceManager();
1341  StackDiagVector CallStack;
1342  InterestingExprs IE;
1343
1344  const ExplodedNode *NextNode = N->pred_empty() ? NULL : *(N->pred_begin());
1345  while (NextNode) {
1346    N = NextNode;
1347    NextNode = N->getFirstPred();
1348    ProgramPoint P = N->getLocation();
1349
1350    do {
1351      if (Optional<PostStmt> PS = P.getAs<PostStmt>()) {
1352        if (const Expr *Ex = PS->getStmtAs<Expr>())
1353          reversePropagateIntererstingSymbols(*PDB.getBugReport(), IE,
1354                                              N->getState().getPtr(), Ex,
1355                                              N->getLocationContext());
1356      }
1357
1358      if (Optional<CallExitEnd> CE = P.getAs<CallExitEnd>()) {
1359        const Stmt *S = CE->getCalleeContext()->getCallSite();
1360        if (const Expr *Ex = dyn_cast_or_null<Expr>(S)) {
1361            reversePropagateIntererstingSymbols(*PDB.getBugReport(), IE,
1362                                                N->getState().getPtr(), Ex,
1363                                                N->getLocationContext());
1364        }
1365
1366        PathDiagnosticCallPiece *C =
1367          PathDiagnosticCallPiece::construct(N, *CE, SM);
1368        LCM[&C->path] = CE->getCalleeContext();
1369
1370        EB.addEdge(C->callReturn, /*AlwaysAdd=*/true, /*IsPostJump=*/true);
1371        EB.flushLocations();
1372
1373        PD.getActivePath().push_front(C);
1374        PD.pushActivePath(&C->path);
1375        CallStack.push_back(StackDiagPair(C, N));
1376        break;
1377      }
1378
1379      // Pop the call hierarchy if we are done walking the contents
1380      // of a function call.
1381      if (Optional<CallEnter> CE = P.getAs<CallEnter>()) {
1382        // Add an edge to the start of the function.
1383        const Decl *D = CE->getCalleeContext()->getDecl();
1384        PathDiagnosticLocation pos =
1385          PathDiagnosticLocation::createBegin(D, SM);
1386        EB.addEdge(pos);
1387
1388        // Flush all locations, and pop the active path.
1389        bool VisitedEntireCall = PD.isWithinCall();
1390        EB.flushLocations();
1391        PD.popActivePath();
1392        PDB.LC = N->getLocationContext();
1393
1394        // Either we just added a bunch of stuff to the top-level path, or
1395        // we have a previous CallExitEnd.  If the former, it means that the
1396        // path terminated within a function call.  We must then take the
1397        // current contents of the active path and place it within
1398        // a new PathDiagnosticCallPiece.
1399        PathDiagnosticCallPiece *C;
1400        if (VisitedEntireCall) {
1401          C = cast<PathDiagnosticCallPiece>(PD.getActivePath().front());
1402        } else {
1403          const Decl *Caller = CE->getLocationContext()->getDecl();
1404          C = PathDiagnosticCallPiece::construct(PD.getActivePath(), Caller);
1405          LCM[&C->path] = CE->getCalleeContext();
1406        }
1407
1408        C->setCallee(*CE, SM);
1409        EB.addContext(C->getLocation());
1410
1411        if (!CallStack.empty()) {
1412          assert(CallStack.back().first == C);
1413          CallStack.pop_back();
1414        }
1415        break;
1416      }
1417
1418      // Note that is important that we update the LocationContext
1419      // after looking at CallExits.  CallExit basically adds an
1420      // edge in the *caller*, so we don't want to update the LocationContext
1421      // too soon.
1422      PDB.LC = N->getLocationContext();
1423
1424      // Block edges.
1425      if (Optional<BlockEdge> BE = P.getAs<BlockEdge>()) {
1426        // Does this represent entering a call?  If so, look at propagating
1427        // interesting symbols across call boundaries.
1428        if (NextNode) {
1429          const LocationContext *CallerCtx = NextNode->getLocationContext();
1430          const LocationContext *CalleeCtx = PDB.LC;
1431          if (CallerCtx != CalleeCtx) {
1432            reversePropagateInterestingSymbols(*PDB.getBugReport(), IE,
1433                                               N->getState().getPtr(),
1434                                               CalleeCtx, CallerCtx);
1435          }
1436        }
1437
1438        // Are we jumping to the head of a loop?  Add a special diagnostic.
1439        if (const Stmt *Loop = BE->getSrc()->getLoopTarget()) {
1440          PathDiagnosticLocation L(Loop, SM, PDB.LC);
1441          const CompoundStmt *CS = NULL;
1442
1443          if (const ForStmt *FS = dyn_cast<ForStmt>(Loop))
1444            CS = dyn_cast<CompoundStmt>(FS->getBody());
1445          else if (const WhileStmt *WS = dyn_cast<WhileStmt>(Loop))
1446            CS = dyn_cast<CompoundStmt>(WS->getBody());
1447
1448          PathDiagnosticEventPiece *p =
1449            new PathDiagnosticEventPiece(L,
1450                                        "Looping back to the head of the loop");
1451          p->setPrunable(true);
1452
1453          EB.addEdge(p->getLocation(), true);
1454          PD.getActivePath().push_front(p);
1455
1456          if (CS) {
1457            PathDiagnosticLocation BL =
1458              PathDiagnosticLocation::createEndBrace(CS, SM);
1459            EB.addEdge(BL);
1460          }
1461        }
1462
1463        const CFGBlock *BSrc = BE->getSrc();
1464        ParentMap &PM = PDB.getParentMap();
1465
1466        if (const Stmt *Term = BSrc->getTerminator()) {
1467          // Are we jumping past the loop body without ever executing the
1468          // loop (because the condition was false)?
1469          if (isLoopJumpPastBody(Term, &*BE) &&
1470              !isInLoopBody(PM,
1471                            getStmtBeforeCond(PM,
1472                                              BSrc->getTerminatorCondition(),
1473                                              N),
1474                            Term)) {
1475            PathDiagnosticLocation L(Term, SM, PDB.LC);
1476            PathDiagnosticEventPiece *PE =
1477                new PathDiagnosticEventPiece(L, "Loop body executed 0 times");
1478            PE->setPrunable(true);
1479
1480            EB.addEdge(PE->getLocation(), true);
1481            PD.getActivePath().push_front(PE);
1482          }
1483
1484          // In any case, add the terminator as the current statement
1485          // context for control edges.
1486          EB.addContext(Term);
1487        }
1488
1489        break;
1490      }
1491
1492      if (Optional<BlockEntrance> BE = P.getAs<BlockEntrance>()) {
1493        Optional<CFGElement> First = BE->getFirstElement();
1494        if (Optional<CFGStmt> S = First ? First->getAs<CFGStmt>() : None) {
1495          const Stmt *stmt = S->getStmt();
1496          if (IsControlFlowExpr(stmt)) {
1497            // Add the proper context for '&&', '||', and '?'.
1498            EB.addContext(stmt);
1499          }
1500          else
1501            EB.addExtendedContext(PDB.getEnclosingStmtLocation(stmt).asStmt());
1502        }
1503
1504        break;
1505      }
1506
1507
1508    } while (0);
1509
1510    if (!NextNode)
1511      continue;
1512
1513    // Add pieces from custom visitors.
1514    BugReport *R = PDB.getBugReport();
1515    for (ArrayRef<BugReporterVisitor *>::iterator I = visitors.begin(),
1516                                                  E = visitors.end();
1517         I != E; ++I) {
1518      if (PathDiagnosticPiece *p = (*I)->VisitNode(N, NextNode, PDB, *R)) {
1519        const PathDiagnosticLocation &Loc = p->getLocation();
1520        EB.addEdge(Loc, true);
1521        PD.getActivePath().push_front(p);
1522        updateStackPiecesWithMessage(p, CallStack);
1523
1524        if (const Stmt *S = Loc.asStmt())
1525          EB.addExtendedContext(PDB.getEnclosingStmtLocation(S).asStmt());
1526      }
1527    }
1528  }
1529
1530  return PDB.getBugReport()->isValid();
1531}
1532
1533/// \brief Adds a sanitized control-flow diagnostic edge to a path.
1534static void addEdgeToPath(PathPieces &path,
1535                          PathDiagnosticLocation &PrevLoc,
1536                          PathDiagnosticLocation NewLoc,
1537                          const LocationContext *LC) {
1538  if (!NewLoc.isValid())
1539    return;
1540
1541  SourceLocation NewLocL = NewLoc.asLocation();
1542  if (NewLocL.isInvalid() || NewLocL.isMacroID())
1543    return;
1544
1545  if (!PrevLoc.isValid()) {
1546    PrevLoc = NewLoc;
1547    return;
1548  }
1549
1550  // FIXME: ignore intra-macro edges for now.
1551  if (NewLoc.asLocation().getExpansionLoc() ==
1552      PrevLoc.asLocation().getExpansionLoc())
1553    return;
1554
1555  path.push_front(new PathDiagnosticControlFlowPiece(NewLoc,
1556                                                     PrevLoc));
1557  PrevLoc = NewLoc;
1558}
1559
1560static bool
1561GenerateAlternateExtensivePathDiagnostic(PathDiagnostic& PD,
1562                                         PathDiagnosticBuilder &PDB,
1563                                         const ExplodedNode *N,
1564                                         LocationContextMap &LCM,
1565                                      ArrayRef<BugReporterVisitor *> visitors) {
1566
1567  BugReport *report = PDB.getBugReport();
1568  const SourceManager& SM = PDB.getSourceManager();
1569  StackDiagVector CallStack;
1570  InterestingExprs IE;
1571
1572  // Record the last location for a given visited stack frame.
1573  llvm::DenseMap<const StackFrameContext *, PathDiagnosticLocation>
1574    PrevLocMap;
1575
1576  const ExplodedNode *NextNode = N->getFirstPred();
1577  while (NextNode) {
1578    N = NextNode;
1579    NextNode = N->getFirstPred();
1580    ProgramPoint P = N->getLocation();
1581    const LocationContext *LC = N->getLocationContext();
1582    assert(!LCM[&PD.getActivePath()] || LCM[&PD.getActivePath()] == LC);
1583    LCM[&PD.getActivePath()] = LC;
1584    PathDiagnosticLocation &PrevLoc = PrevLocMap[LC->getCurrentStackFrame()];
1585
1586    do {
1587      if (Optional<PostStmt> PS = P.getAs<PostStmt>()) {
1588        // For expressions, make sure we propagate the
1589        // interesting symbols correctly.
1590        if (const Expr *Ex = PS->getStmtAs<Expr>())
1591          reversePropagateIntererstingSymbols(*PDB.getBugReport(), IE,
1592                                              N->getState().getPtr(), Ex,
1593                                              N->getLocationContext());
1594
1595        PathDiagnosticLocation L =
1596          PathDiagnosticLocation(PS->getStmt(), SM, LC);
1597        addEdgeToPath(PD.getActivePath(), PrevLoc, L, LC);
1598        break;
1599      }
1600
1601      // Have we encountered an exit from a function call?
1602      if (Optional<CallExitEnd> CE = P.getAs<CallExitEnd>()) {
1603        const Stmt *S = CE->getCalleeContext()->getCallSite();
1604        // Propagate the interesting symbols accordingly.
1605        if (const Expr *Ex = dyn_cast_or_null<Expr>(S)) {
1606          reversePropagateIntererstingSymbols(*PDB.getBugReport(), IE,
1607                                              N->getState().getPtr(), Ex,
1608                                              N->getLocationContext());
1609        }
1610
1611        // We are descending into a call (backwards).  Construct
1612        // a new call piece to contain the path pieces for that call.
1613        PathDiagnosticCallPiece *C =
1614          PathDiagnosticCallPiece::construct(N, *CE, SM);
1615
1616        // Record the location context for this call piece.
1617        LCM[&C->path] = CE->getCalleeContext();
1618
1619        // Add the edge to the return site.
1620        addEdgeToPath(PD.getActivePath(), PrevLoc, C->callReturn, LC);
1621
1622        // Make the contents of the call the active path for now.
1623        PD.pushActivePath(&C->path);
1624        CallStack.push_back(StackDiagPair(C, N));
1625        break;
1626      }
1627
1628      // Have we encountered an entrance to a call?  It may be
1629      // the case that we have not encountered a matching
1630      // call exit before this point.  This means that the path
1631      // terminated within the call itself.
1632      if (Optional<CallEnter> CE = P.getAs<CallEnter>()) {
1633        // Add an edge to the start of the function.
1634        const Decl *D = CE->getCalleeContext()->getDecl();
1635        addEdgeToPath(PD.getActivePath(), PrevLoc,
1636                      PathDiagnosticLocation::createBegin(D, SM), LC);
1637
1638        // Did we visit an entire call?
1639        bool VisitedEntireCall = PD.isWithinCall();
1640        PD.popActivePath();
1641
1642        PathDiagnosticCallPiece *C;
1643        if (VisitedEntireCall) {
1644          C = cast<PathDiagnosticCallPiece>(PD.getActivePath().front());
1645        } else {
1646          const Decl *Caller = CE->getLocationContext()->getDecl();
1647          C = PathDiagnosticCallPiece::construct(PD.getActivePath(), Caller);
1648          LCM[&C->path] = CE->getCalleeContext();
1649        }
1650        C->setCallee(*CE, SM);
1651
1652        if (!CallStack.empty()) {
1653          assert(CallStack.back().first == C);
1654          CallStack.pop_back();
1655        }
1656        break;
1657      }
1658
1659      // Block edges.
1660      if (Optional<BlockEdge> BE = P.getAs<BlockEdge>()) {
1661        // Does this represent entering a call?  If so, look at propagating
1662        // interesting symbols across call boundaries.
1663        if (NextNode) {
1664          const LocationContext *CallerCtx = NextNode->getLocationContext();
1665          const LocationContext *CalleeCtx = PDB.LC;
1666          if (CallerCtx != CalleeCtx) {
1667            reversePropagateInterestingSymbols(*PDB.getBugReport(), IE,
1668                                               N->getState().getPtr(),
1669                                               CalleeCtx, CallerCtx);
1670          }
1671        }
1672
1673        // Are we jumping to the head of a loop?  Add a special diagnostic.
1674        if (const Stmt *Loop = BE->getSrc()->getLoopTarget()) {
1675          PathDiagnosticLocation L(Loop, SM, PDB.LC);
1676          const CompoundStmt *CS = NULL;
1677
1678          if (const ForStmt *FS = dyn_cast<ForStmt>(Loop))
1679            CS = dyn_cast<CompoundStmt>(FS->getBody());
1680          else if (const WhileStmt *WS = dyn_cast<WhileStmt>(Loop))
1681            CS = dyn_cast<CompoundStmt>(WS->getBody());
1682
1683          PathDiagnosticEventPiece *p =
1684            new PathDiagnosticEventPiece(L, "Looping back to the head "
1685                                            "of the loop");
1686          p->setPrunable(true);
1687
1688          addEdgeToPath(PD.getActivePath(), PrevLoc, p->getLocation(), LC);
1689          PD.getActivePath().push_front(p);
1690
1691          if (CS) {
1692            addEdgeToPath(PD.getActivePath(), PrevLoc,
1693                          PathDiagnosticLocation::createEndBrace(CS, SM), LC);
1694          }
1695        }
1696
1697        const CFGBlock *BSrc = BE->getSrc();
1698        ParentMap &PM = PDB.getParentMap();
1699
1700        if (const Stmt *Term = BSrc->getTerminator()) {
1701          // Are we jumping past the loop body without ever executing the
1702          // loop (because the condition was false)?
1703          if (isLoopJumpPastBody(Term, &*BE) &&
1704              !isInLoopBody(PM,
1705                            getStmtBeforeCond(PM,
1706                                              BSrc->getTerminatorCondition(),
1707                                              N),
1708                            Term))
1709          {
1710            PathDiagnosticLocation L(Term, SM, PDB.LC);
1711            PathDiagnosticEventPiece *PE =
1712              new PathDiagnosticEventPiece(L, "Loop body executed 0 times");
1713            PE->setPrunable(true);
1714            addEdgeToPath(PD.getActivePath(), PrevLoc,
1715                          PE->getLocation(), LC);
1716            PD.getActivePath().push_front(PE);
1717          }
1718        }
1719        break;
1720      }
1721    } while (0);
1722
1723    if (!NextNode)
1724      continue;
1725
1726    // Add pieces from custom visitors.
1727    for (ArrayRef<BugReporterVisitor *>::iterator I = visitors.begin(),
1728         E = visitors.end();
1729         I != E; ++I) {
1730      if (PathDiagnosticPiece *p = (*I)->VisitNode(N, NextNode, PDB, *report)) {
1731        addEdgeToPath(PD.getActivePath(), PrevLoc, p->getLocation(), LC);
1732        PD.getActivePath().push_front(p);
1733        updateStackPiecesWithMessage(p, CallStack);
1734      }
1735    }
1736  }
1737
1738  return report->isValid();
1739}
1740
1741const Stmt *getLocStmt(PathDiagnosticLocation L) {
1742  if (!L.isValid())
1743    return 0;
1744  return L.asStmt();
1745}
1746
1747const Stmt *getStmtParent(const Stmt *S, ParentMap &PM) {
1748  if (!S)
1749    return 0;
1750  return PM.getParentIgnoreParens(S);
1751}
1752
1753static bool optimizeEdges(PathPieces &path,
1754                          LocationContextMap &LCM) {
1755  bool hasChanges = false;
1756  const LocationContext *LC = LCM[&path];
1757  assert(LC);
1758  bool isFirst = true;
1759
1760  for (PathPieces::iterator I = path.begin(), E = path.end(); I != E; ++I) {
1761    PathPieces::iterator NextI = I; ++NextI;
1762    if (NextI == E)
1763      break;
1764
1765    // Optimize subpaths.
1766    if (PathDiagnosticCallPiece *CallI = dyn_cast<PathDiagnosticCallPiece>(*I)){
1767      while (optimizeEdges(CallI->path, LCM)) {}
1768      continue;
1769    }
1770
1771    // Pattern match the current piece and its successor.
1772    PathDiagnosticControlFlowPiece *PieceI =
1773      dyn_cast<PathDiagnosticControlFlowPiece>(*I);
1774
1775    if (!PieceI)
1776      continue;
1777
1778    ParentMap &PM = LC->getParentMap();
1779    const Stmt *s1Start = getLocStmt(PieceI->getStartLocation());
1780    const Stmt *s1End   = getLocStmt(PieceI->getEndLocation());
1781    const Stmt *level1 = getStmtParent(s1Start, PM);
1782    const Stmt *level2 = getStmtParent(s1End, PM);
1783
1784    if (isFirst) {
1785      isFirst = false;
1786      // Apply the "first edge" case for Rule III. here.
1787      if (level1 && level2 && level2 == PM.getParent(level1)) {
1788        path.erase(I);
1789        // Since we are erasing the current edge at the start of the
1790        // path, just return now so we start analyzing the start of the path
1791        // again.
1792        return true;
1793      }
1794    }
1795
1796    PathDiagnosticControlFlowPiece *PieceNextI =
1797      dyn_cast<PathDiagnosticControlFlowPiece>(*NextI);
1798
1799    if (!PieceNextI)
1800      continue;
1801
1802    const Stmt *s2Start = getLocStmt(PieceNextI->getStartLocation());
1803    const Stmt *s2End   = getLocStmt(PieceNextI->getEndLocation());
1804    const Stmt *level3 = getStmtParent(s2Start, PM);
1805    const Stmt *level4 = getStmtParent(s2End, PM);
1806
1807    // Rule I.
1808    //
1809    // If we have two consecutive control edges whose end/begin locations
1810    // are at the same level (i.e., parents), merge them.
1811    //
1812    // For example:
1813    //
1814    // (1.1 -> 1.2) -> (1.2 -> 1.3) becomes (1.1 -> 1.3) because the common
1815    // parent is '1'.  Here '1.1' represents the hierarchy of statements.
1816    //
1817    // NOTE: this will be limited later in cases where we add barriers
1818    // to prevent this optimization.
1819    //
1820    if (level1 && level1 == level2 && level1 == level3 && level1 == level4) {
1821      PieceI->setEndLocation(PieceNextI->getEndLocation());
1822      path.erase(NextI);
1823      hasChanges = true;
1824      continue;
1825    }
1826
1827    // Rule II.
1828    //
1829    // If we have two consecutive control edges where we decend to a
1830    // subexpression and then pop out merge them.
1831    //
1832    // NOTE: this will be limited later in cases where we add barriers
1833    // to prevent this optimization.
1834    //
1835    // For example:
1836    //
1837    // (1.1 -> 1.1.1) -> (1.1.1 -> 1.2) becomes (1.1 -> 1.2).
1838    if (level1 && level2 &&
1839        level1 == level4 &&
1840        level2 == level3 && PM.getParentIgnoreParens(level2) == level1) {
1841      PieceI->setEndLocation(PieceNextI->getEndLocation());
1842      path.erase(NextI);
1843      hasChanges = true;
1844      continue;
1845    }
1846
1847    // Rule III.
1848    //
1849    // Eliminate unnecessary edges where we descend to a subexpression from
1850    // a statement at the same level as our parent.
1851    //
1852    // NOTE: this will be limited later in cases where we add barriers
1853    // to prevent this optimization.
1854    //
1855    // For example:
1856    //
1857    // (1.1 -> 1.1.1) -> (1.1.1 -> X) becomes (1.1 -> X).
1858    //
1859    if (level1 && level2 && level1 == PM.getParentIgnoreParens(level2)) {
1860      PieceI->setEndLocation(PieceNextI->getEndLocation());
1861      path.erase(NextI);
1862      hasChanges = true;
1863      continue;
1864    }
1865
1866    // Rule IV.
1867    //
1868    // Eliminate unnecessary edges where we ascend from a subexpression to
1869    // a statement at the same level as our parent.
1870    //
1871    // NOTE: this will be limited later in cases where we add barriers
1872    // to prevent this optimization.
1873    //
1874    // For example:
1875    //
1876    // (X -> 1.1.1) -> (1.1.1 -> 1.1) becomes (X -> 1.1).
1877    // [first edge] (1.1.1 -> 1.1) -> eliminate
1878    //
1879    if (level2 && level4 && level2 == level3 && level4 == PM.getParent(level2)){
1880      PieceI->setEndLocation(PieceNextI->getEndLocation());
1881      path.erase(NextI);
1882      hasChanges = true;
1883      continue;
1884    }
1885  }
1886
1887  // No changes.
1888  return hasChanges;
1889}
1890
1891//===----------------------------------------------------------------------===//
1892// Methods for BugType and subclasses.
1893//===----------------------------------------------------------------------===//
1894BugType::~BugType() { }
1895
1896void BugType::FlushReports(BugReporter &BR) {}
1897
1898void BuiltinBug::anchor() {}
1899
1900//===----------------------------------------------------------------------===//
1901// Methods for BugReport and subclasses.
1902//===----------------------------------------------------------------------===//
1903
1904void BugReport::NodeResolver::anchor() {}
1905
1906void BugReport::addVisitor(BugReporterVisitor* visitor) {
1907  if (!visitor)
1908    return;
1909
1910  llvm::FoldingSetNodeID ID;
1911  visitor->Profile(ID);
1912  void *InsertPos;
1913
1914  if (CallbacksSet.FindNodeOrInsertPos(ID, InsertPos)) {
1915    delete visitor;
1916    return;
1917  }
1918
1919  CallbacksSet.InsertNode(visitor, InsertPos);
1920  Callbacks.push_back(visitor);
1921  ++ConfigurationChangeToken;
1922}
1923
1924BugReport::~BugReport() {
1925  for (visitor_iterator I = visitor_begin(), E = visitor_end(); I != E; ++I) {
1926    delete *I;
1927  }
1928  while (!interestingSymbols.empty()) {
1929    popInterestingSymbolsAndRegions();
1930  }
1931}
1932
1933const Decl *BugReport::getDeclWithIssue() const {
1934  if (DeclWithIssue)
1935    return DeclWithIssue;
1936
1937  const ExplodedNode *N = getErrorNode();
1938  if (!N)
1939    return 0;
1940
1941  const LocationContext *LC = N->getLocationContext();
1942  return LC->getCurrentStackFrame()->getDecl();
1943}
1944
1945void BugReport::Profile(llvm::FoldingSetNodeID& hash) const {
1946  hash.AddPointer(&BT);
1947  hash.AddString(Description);
1948  PathDiagnosticLocation UL = getUniqueingLocation();
1949  if (UL.isValid()) {
1950    UL.Profile(hash);
1951  } else if (Location.isValid()) {
1952    Location.Profile(hash);
1953  } else {
1954    assert(ErrorNode);
1955    hash.AddPointer(GetCurrentOrPreviousStmt(ErrorNode));
1956  }
1957
1958  for (SmallVectorImpl<SourceRange>::const_iterator I =
1959      Ranges.begin(), E = Ranges.end(); I != E; ++I) {
1960    const SourceRange range = *I;
1961    if (!range.isValid())
1962      continue;
1963    hash.AddInteger(range.getBegin().getRawEncoding());
1964    hash.AddInteger(range.getEnd().getRawEncoding());
1965  }
1966}
1967
1968void BugReport::markInteresting(SymbolRef sym) {
1969  if (!sym)
1970    return;
1971
1972  // If the symbol wasn't already in our set, note a configuration change.
1973  if (getInterestingSymbols().insert(sym).second)
1974    ++ConfigurationChangeToken;
1975
1976  if (const SymbolMetadata *meta = dyn_cast<SymbolMetadata>(sym))
1977    getInterestingRegions().insert(meta->getRegion());
1978}
1979
1980void BugReport::markInteresting(const MemRegion *R) {
1981  if (!R)
1982    return;
1983
1984  // If the base region wasn't already in our set, note a configuration change.
1985  R = R->getBaseRegion();
1986  if (getInterestingRegions().insert(R).second)
1987    ++ConfigurationChangeToken;
1988
1989  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R))
1990    getInterestingSymbols().insert(SR->getSymbol());
1991}
1992
1993void BugReport::markInteresting(SVal V) {
1994  markInteresting(V.getAsRegion());
1995  markInteresting(V.getAsSymbol());
1996}
1997
1998void BugReport::markInteresting(const LocationContext *LC) {
1999  if (!LC)
2000    return;
2001  InterestingLocationContexts.insert(LC);
2002}
2003
2004bool BugReport::isInteresting(SVal V) {
2005  return isInteresting(V.getAsRegion()) || isInteresting(V.getAsSymbol());
2006}
2007
2008bool BugReport::isInteresting(SymbolRef sym) {
2009  if (!sym)
2010    return false;
2011  // We don't currently consider metadata symbols to be interesting
2012  // even if we know their region is interesting. Is that correct behavior?
2013  return getInterestingSymbols().count(sym);
2014}
2015
2016bool BugReport::isInteresting(const MemRegion *R) {
2017  if (!R)
2018    return false;
2019  R = R->getBaseRegion();
2020  bool b = getInterestingRegions().count(R);
2021  if (b)
2022    return true;
2023  if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R))
2024    return getInterestingSymbols().count(SR->getSymbol());
2025  return false;
2026}
2027
2028bool BugReport::isInteresting(const LocationContext *LC) {
2029  if (!LC)
2030    return false;
2031  return InterestingLocationContexts.count(LC);
2032}
2033
2034void BugReport::lazyInitializeInterestingSets() {
2035  if (interestingSymbols.empty()) {
2036    interestingSymbols.push_back(new Symbols());
2037    interestingRegions.push_back(new Regions());
2038  }
2039}
2040
2041BugReport::Symbols &BugReport::getInterestingSymbols() {
2042  lazyInitializeInterestingSets();
2043  return *interestingSymbols.back();
2044}
2045
2046BugReport::Regions &BugReport::getInterestingRegions() {
2047  lazyInitializeInterestingSets();
2048  return *interestingRegions.back();
2049}
2050
2051void BugReport::pushInterestingSymbolsAndRegions() {
2052  interestingSymbols.push_back(new Symbols(getInterestingSymbols()));
2053  interestingRegions.push_back(new Regions(getInterestingRegions()));
2054}
2055
2056void BugReport::popInterestingSymbolsAndRegions() {
2057  delete interestingSymbols.back();
2058  interestingSymbols.pop_back();
2059  delete interestingRegions.back();
2060  interestingRegions.pop_back();
2061}
2062
2063const Stmt *BugReport::getStmt() const {
2064  if (!ErrorNode)
2065    return 0;
2066
2067  ProgramPoint ProgP = ErrorNode->getLocation();
2068  const Stmt *S = NULL;
2069
2070  if (Optional<BlockEntrance> BE = ProgP.getAs<BlockEntrance>()) {
2071    CFGBlock &Exit = ProgP.getLocationContext()->getCFG()->getExit();
2072    if (BE->getBlock() == &Exit)
2073      S = GetPreviousStmt(ErrorNode);
2074  }
2075  if (!S)
2076    S = PathDiagnosticLocation::getStmt(ErrorNode);
2077
2078  return S;
2079}
2080
2081std::pair<BugReport::ranges_iterator, BugReport::ranges_iterator>
2082BugReport::getRanges() {
2083    // If no custom ranges, add the range of the statement corresponding to
2084    // the error node.
2085    if (Ranges.empty()) {
2086      if (const Expr *E = dyn_cast_or_null<Expr>(getStmt()))
2087        addRange(E->getSourceRange());
2088      else
2089        return std::make_pair(ranges_iterator(), ranges_iterator());
2090    }
2091
2092    // User-specified absence of range info.
2093    if (Ranges.size() == 1 && !Ranges.begin()->isValid())
2094      return std::make_pair(ranges_iterator(), ranges_iterator());
2095
2096    return std::make_pair(Ranges.begin(), Ranges.end());
2097}
2098
2099PathDiagnosticLocation BugReport::getLocation(const SourceManager &SM) const {
2100  if (ErrorNode) {
2101    assert(!Location.isValid() &&
2102     "Either Location or ErrorNode should be specified but not both.");
2103    return PathDiagnosticLocation::createEndOfPath(ErrorNode, SM);
2104  } else {
2105    assert(Location.isValid());
2106    return Location;
2107  }
2108
2109  return PathDiagnosticLocation();
2110}
2111
2112//===----------------------------------------------------------------------===//
2113// Methods for BugReporter and subclasses.
2114//===----------------------------------------------------------------------===//
2115
2116BugReportEquivClass::~BugReportEquivClass() { }
2117GRBugReporter::~GRBugReporter() { }
2118BugReporterData::~BugReporterData() {}
2119
2120ExplodedGraph &GRBugReporter::getGraph() { return Eng.getGraph(); }
2121
2122ProgramStateManager&
2123GRBugReporter::getStateManager() { return Eng.getStateManager(); }
2124
2125BugReporter::~BugReporter() {
2126  FlushReports();
2127
2128  // Free the bug reports we are tracking.
2129  typedef std::vector<BugReportEquivClass *> ContTy;
2130  for (ContTy::iterator I = EQClassesVector.begin(), E = EQClassesVector.end();
2131       I != E; ++I) {
2132    delete *I;
2133  }
2134}
2135
2136void BugReporter::FlushReports() {
2137  if (BugTypes.isEmpty())
2138    return;
2139
2140  // First flush the warnings for each BugType.  This may end up creating new
2141  // warnings and new BugTypes.
2142  // FIXME: Only NSErrorChecker needs BugType's FlushReports.
2143  // Turn NSErrorChecker into a proper checker and remove this.
2144  SmallVector<const BugType*, 16> bugTypes;
2145  for (BugTypesTy::iterator I=BugTypes.begin(), E=BugTypes.end(); I!=E; ++I)
2146    bugTypes.push_back(*I);
2147  for (SmallVector<const BugType*, 16>::iterator
2148         I = bugTypes.begin(), E = bugTypes.end(); I != E; ++I)
2149    const_cast<BugType*>(*I)->FlushReports(*this);
2150
2151  // We need to flush reports in deterministic order to ensure the order
2152  // of the reports is consistent between runs.
2153  typedef std::vector<BugReportEquivClass *> ContVecTy;
2154  for (ContVecTy::iterator EI=EQClassesVector.begin(), EE=EQClassesVector.end();
2155       EI != EE; ++EI){
2156    BugReportEquivClass& EQ = **EI;
2157    FlushReport(EQ);
2158  }
2159
2160  // BugReporter owns and deletes only BugTypes created implicitly through
2161  // EmitBasicReport.
2162  // FIXME: There are leaks from checkers that assume that the BugTypes they
2163  // create will be destroyed by the BugReporter.
2164  for (llvm::StringMap<BugType*>::iterator
2165         I = StrBugTypes.begin(), E = StrBugTypes.end(); I != E; ++I)
2166    delete I->second;
2167
2168  // Remove all references to the BugType objects.
2169  BugTypes = F.getEmptySet();
2170}
2171
2172//===----------------------------------------------------------------------===//
2173// PathDiagnostics generation.
2174//===----------------------------------------------------------------------===//
2175
2176namespace {
2177/// A wrapper around a report graph, which contains only a single path, and its
2178/// node maps.
2179class ReportGraph {
2180public:
2181  InterExplodedGraphMap BackMap;
2182  OwningPtr<ExplodedGraph> Graph;
2183  const ExplodedNode *ErrorNode;
2184  size_t Index;
2185};
2186
2187/// A wrapper around a trimmed graph and its node maps.
2188class TrimmedGraph {
2189  InterExplodedGraphMap InverseMap;
2190
2191  typedef llvm::DenseMap<const ExplodedNode *, unsigned> PriorityMapTy;
2192  PriorityMapTy PriorityMap;
2193
2194  typedef std::pair<const ExplodedNode *, size_t> NodeIndexPair;
2195  SmallVector<NodeIndexPair, 32> ReportNodes;
2196
2197  OwningPtr<ExplodedGraph> G;
2198
2199  /// A helper class for sorting ExplodedNodes by priority.
2200  template <bool Descending>
2201  class PriorityCompare {
2202    const PriorityMapTy &PriorityMap;
2203
2204  public:
2205    PriorityCompare(const PriorityMapTy &M) : PriorityMap(M) {}
2206
2207    bool operator()(const ExplodedNode *LHS, const ExplodedNode *RHS) const {
2208      PriorityMapTy::const_iterator LI = PriorityMap.find(LHS);
2209      PriorityMapTy::const_iterator RI = PriorityMap.find(RHS);
2210      PriorityMapTy::const_iterator E = PriorityMap.end();
2211
2212      if (LI == E)
2213        return Descending;
2214      if (RI == E)
2215        return !Descending;
2216
2217      return Descending ? LI->second > RI->second
2218                        : LI->second < RI->second;
2219    }
2220
2221    bool operator()(const NodeIndexPair &LHS, const NodeIndexPair &RHS) const {
2222      return (*this)(LHS.first, RHS.first);
2223    }
2224  };
2225
2226public:
2227  TrimmedGraph(const ExplodedGraph *OriginalGraph,
2228               ArrayRef<const ExplodedNode *> Nodes);
2229
2230  bool popNextReportGraph(ReportGraph &GraphWrapper);
2231};
2232}
2233
2234TrimmedGraph::TrimmedGraph(const ExplodedGraph *OriginalGraph,
2235                           ArrayRef<const ExplodedNode *> Nodes) {
2236  // The trimmed graph is created in the body of the constructor to ensure
2237  // that the DenseMaps have been initialized already.
2238  InterExplodedGraphMap ForwardMap;
2239  G.reset(OriginalGraph->trim(Nodes, &ForwardMap, &InverseMap));
2240
2241  // Find the (first) error node in the trimmed graph.  We just need to consult
2242  // the node map which maps from nodes in the original graph to nodes
2243  // in the new graph.
2244  llvm::SmallPtrSet<const ExplodedNode *, 32> RemainingNodes;
2245
2246  for (unsigned i = 0, count = Nodes.size(); i < count; ++i) {
2247    if (const ExplodedNode *NewNode = ForwardMap.lookup(Nodes[i])) {
2248      ReportNodes.push_back(std::make_pair(NewNode, i));
2249      RemainingNodes.insert(NewNode);
2250    }
2251  }
2252
2253  assert(!RemainingNodes.empty() && "No error node found in the trimmed graph");
2254
2255  // Perform a forward BFS to find all the shortest paths.
2256  std::queue<const ExplodedNode *> WS;
2257
2258  assert(G->num_roots() == 1);
2259  WS.push(*G->roots_begin());
2260  unsigned Priority = 0;
2261
2262  while (!WS.empty()) {
2263    const ExplodedNode *Node = WS.front();
2264    WS.pop();
2265
2266    PriorityMapTy::iterator PriorityEntry;
2267    bool IsNew;
2268    llvm::tie(PriorityEntry, IsNew) =
2269      PriorityMap.insert(std::make_pair(Node, Priority));
2270    ++Priority;
2271
2272    if (!IsNew) {
2273      assert(PriorityEntry->second <= Priority);
2274      continue;
2275    }
2276
2277    if (RemainingNodes.erase(Node))
2278      if (RemainingNodes.empty())
2279        break;
2280
2281    for (ExplodedNode::const_pred_iterator I = Node->succ_begin(),
2282                                           E = Node->succ_end();
2283         I != E; ++I)
2284      WS.push(*I);
2285  }
2286
2287  // Sort the error paths from longest to shortest.
2288  std::sort(ReportNodes.begin(), ReportNodes.end(),
2289            PriorityCompare<true>(PriorityMap));
2290}
2291
2292bool TrimmedGraph::popNextReportGraph(ReportGraph &GraphWrapper) {
2293  if (ReportNodes.empty())
2294    return false;
2295
2296  const ExplodedNode *OrigN;
2297  llvm::tie(OrigN, GraphWrapper.Index) = ReportNodes.pop_back_val();
2298  assert(PriorityMap.find(OrigN) != PriorityMap.end() &&
2299         "error node not accessible from root");
2300
2301  // Create a new graph with a single path.  This is the graph
2302  // that will be returned to the caller.
2303  ExplodedGraph *GNew = new ExplodedGraph();
2304  GraphWrapper.Graph.reset(GNew);
2305  GraphWrapper.BackMap.clear();
2306
2307  // Now walk from the error node up the BFS path, always taking the
2308  // predeccessor with the lowest number.
2309  ExplodedNode *Succ = 0;
2310  while (true) {
2311    // Create the equivalent node in the new graph with the same state
2312    // and location.
2313    ExplodedNode *NewN = GNew->getNode(OrigN->getLocation(), OrigN->getState(),
2314                                       OrigN->isSink());
2315
2316    // Store the mapping to the original node.
2317    InterExplodedGraphMap::const_iterator IMitr = InverseMap.find(OrigN);
2318    assert(IMitr != InverseMap.end() && "No mapping to original node.");
2319    GraphWrapper.BackMap[NewN] = IMitr->second;
2320
2321    // Link up the new node with the previous node.
2322    if (Succ)
2323      Succ->addPredecessor(NewN, *GNew);
2324    else
2325      GraphWrapper.ErrorNode = NewN;
2326
2327    Succ = NewN;
2328
2329    // Are we at the final node?
2330    if (OrigN->pred_empty()) {
2331      GNew->addRoot(NewN);
2332      break;
2333    }
2334
2335    // Find the next predeccessor node.  We choose the node that is marked
2336    // with the lowest BFS number.
2337    OrigN = *std::min_element(OrigN->pred_begin(), OrigN->pred_end(),
2338                          PriorityCompare<false>(PriorityMap));
2339  }
2340
2341  return true;
2342}
2343
2344
2345/// CompactPathDiagnostic - This function postprocesses a PathDiagnostic object
2346///  and collapses PathDiagosticPieces that are expanded by macros.
2347static void CompactPathDiagnostic(PathPieces &path, const SourceManager& SM) {
2348  typedef std::vector<std::pair<IntrusiveRefCntPtr<PathDiagnosticMacroPiece>,
2349                                SourceLocation> > MacroStackTy;
2350
2351  typedef std::vector<IntrusiveRefCntPtr<PathDiagnosticPiece> >
2352          PiecesTy;
2353
2354  MacroStackTy MacroStack;
2355  PiecesTy Pieces;
2356
2357  for (PathPieces::const_iterator I = path.begin(), E = path.end();
2358       I!=E; ++I) {
2359
2360    PathDiagnosticPiece *piece = I->getPtr();
2361
2362    // Recursively compact calls.
2363    if (PathDiagnosticCallPiece *call=dyn_cast<PathDiagnosticCallPiece>(piece)){
2364      CompactPathDiagnostic(call->path, SM);
2365    }
2366
2367    // Get the location of the PathDiagnosticPiece.
2368    const FullSourceLoc Loc = piece->getLocation().asLocation();
2369
2370    // Determine the instantiation location, which is the location we group
2371    // related PathDiagnosticPieces.
2372    SourceLocation InstantiationLoc = Loc.isMacroID() ?
2373                                      SM.getExpansionLoc(Loc) :
2374                                      SourceLocation();
2375
2376    if (Loc.isFileID()) {
2377      MacroStack.clear();
2378      Pieces.push_back(piece);
2379      continue;
2380    }
2381
2382    assert(Loc.isMacroID());
2383
2384    // Is the PathDiagnosticPiece within the same macro group?
2385    if (!MacroStack.empty() && InstantiationLoc == MacroStack.back().second) {
2386      MacroStack.back().first->subPieces.push_back(piece);
2387      continue;
2388    }
2389
2390    // We aren't in the same group.  Are we descending into a new macro
2391    // or are part of an old one?
2392    IntrusiveRefCntPtr<PathDiagnosticMacroPiece> MacroGroup;
2393
2394    SourceLocation ParentInstantiationLoc = InstantiationLoc.isMacroID() ?
2395                                          SM.getExpansionLoc(Loc) :
2396                                          SourceLocation();
2397
2398    // Walk the entire macro stack.
2399    while (!MacroStack.empty()) {
2400      if (InstantiationLoc == MacroStack.back().second) {
2401        MacroGroup = MacroStack.back().first;
2402        break;
2403      }
2404
2405      if (ParentInstantiationLoc == MacroStack.back().second) {
2406        MacroGroup = MacroStack.back().first;
2407        break;
2408      }
2409
2410      MacroStack.pop_back();
2411    }
2412
2413    if (!MacroGroup || ParentInstantiationLoc == MacroStack.back().second) {
2414      // Create a new macro group and add it to the stack.
2415      PathDiagnosticMacroPiece *NewGroup =
2416        new PathDiagnosticMacroPiece(
2417          PathDiagnosticLocation::createSingleLocation(piece->getLocation()));
2418
2419      if (MacroGroup)
2420        MacroGroup->subPieces.push_back(NewGroup);
2421      else {
2422        assert(InstantiationLoc.isFileID());
2423        Pieces.push_back(NewGroup);
2424      }
2425
2426      MacroGroup = NewGroup;
2427      MacroStack.push_back(std::make_pair(MacroGroup, InstantiationLoc));
2428    }
2429
2430    // Finally, add the PathDiagnosticPiece to the group.
2431    MacroGroup->subPieces.push_back(piece);
2432  }
2433
2434  // Now take the pieces and construct a new PathDiagnostic.
2435  path.clear();
2436
2437  for (PiecesTy::iterator I=Pieces.begin(), E=Pieces.end(); I!=E; ++I)
2438    path.push_back(*I);
2439}
2440
2441bool GRBugReporter::generatePathDiagnostic(PathDiagnostic& PD,
2442                                           PathDiagnosticConsumer &PC,
2443                                           ArrayRef<BugReport *> &bugReports) {
2444  assert(!bugReports.empty());
2445
2446  bool HasValid = false;
2447  bool HasInvalid = false;
2448  SmallVector<const ExplodedNode *, 32> errorNodes;
2449  for (ArrayRef<BugReport*>::iterator I = bugReports.begin(),
2450                                      E = bugReports.end(); I != E; ++I) {
2451    if ((*I)->isValid()) {
2452      HasValid = true;
2453      errorNodes.push_back((*I)->getErrorNode());
2454    } else {
2455      // Keep the errorNodes list in sync with the bugReports list.
2456      HasInvalid = true;
2457      errorNodes.push_back(0);
2458    }
2459  }
2460
2461  // If all the reports have been marked invalid by a previous path generation,
2462  // we're done.
2463  if (!HasValid)
2464    return false;
2465
2466  typedef PathDiagnosticConsumer::PathGenerationScheme PathGenerationScheme;
2467  PathGenerationScheme ActiveScheme = PC.getGenerationScheme();
2468
2469  if (ActiveScheme == PathDiagnosticConsumer::Extensive) {
2470    AnalyzerOptions &options = getEngine().getAnalysisManager().options;
2471    if (options.getBooleanOption("path-diagnostics-alternate", true)) {
2472      ActiveScheme = PathDiagnosticConsumer::AlternateExtensive;
2473    }
2474  }
2475
2476  TrimmedGraph TrimG(&getGraph(), errorNodes);
2477  ReportGraph ErrorGraph;
2478
2479  while (TrimG.popNextReportGraph(ErrorGraph)) {
2480    // Find the BugReport with the original location.
2481    assert(ErrorGraph.Index < bugReports.size());
2482    BugReport *R = bugReports[ErrorGraph.Index];
2483    assert(R && "No original report found for sliced graph.");
2484    assert(R->isValid() && "Report selected by trimmed graph marked invalid.");
2485
2486    // Start building the path diagnostic...
2487    PathDiagnosticBuilder PDB(*this, R, ErrorGraph.BackMap, &PC);
2488    const ExplodedNode *N = ErrorGraph.ErrorNode;
2489
2490    // Register additional node visitors.
2491    R->addVisitor(new NilReceiverBRVisitor());
2492    R->addVisitor(new ConditionBRVisitor());
2493    R->addVisitor(new LikelyFalsePositiveSuppressionBRVisitor());
2494
2495    BugReport::VisitorList visitors;
2496    unsigned origReportConfigToken, finalReportConfigToken;
2497    LocationContextMap LCM;
2498
2499    // While generating diagnostics, it's possible the visitors will decide
2500    // new symbols and regions are interesting, or add other visitors based on
2501    // the information they find. If they do, we need to regenerate the path
2502    // based on our new report configuration.
2503    do {
2504      // Get a clean copy of all the visitors.
2505      for (BugReport::visitor_iterator I = R->visitor_begin(),
2506                                       E = R->visitor_end(); I != E; ++I)
2507        visitors.push_back((*I)->clone());
2508
2509      // Clear out the active path from any previous work.
2510      PD.resetPath();
2511      origReportConfigToken = R->getConfigurationChangeToken();
2512
2513      // Generate the very last diagnostic piece - the piece is visible before
2514      // the trace is expanded.
2515      PathDiagnosticPiece *LastPiece = 0;
2516      for (BugReport::visitor_iterator I = visitors.begin(), E = visitors.end();
2517          I != E; ++I) {
2518        if (PathDiagnosticPiece *Piece = (*I)->getEndPath(PDB, N, *R)) {
2519          assert (!LastPiece &&
2520              "There can only be one final piece in a diagnostic.");
2521          LastPiece = Piece;
2522        }
2523      }
2524
2525      if (ActiveScheme != PathDiagnosticConsumer::None) {
2526        if (!LastPiece)
2527          LastPiece = BugReporterVisitor::getDefaultEndPath(PDB, N, *R);
2528        assert(LastPiece);
2529        PD.setEndOfPath(LastPiece);
2530      }
2531
2532      // Make sure we get a clean location context map so we don't
2533      // hold onto old mappings.
2534      LCM.clear();
2535
2536      switch (ActiveScheme) {
2537      case PathDiagnosticConsumer::AlternateExtensive:
2538        GenerateAlternateExtensivePathDiagnostic(PD, PDB, N, LCM, visitors);
2539        break;
2540      case PathDiagnosticConsumer::Extensive:
2541        GenerateExtensivePathDiagnostic(PD, PDB, N, LCM, visitors);
2542        break;
2543      case PathDiagnosticConsumer::Minimal:
2544        GenerateMinimalPathDiagnostic(PD, PDB, N, LCM, visitors);
2545        break;
2546      case PathDiagnosticConsumer::None:
2547        GenerateVisitorsOnlyPathDiagnostic(PD, PDB, N, visitors);
2548        break;
2549      }
2550
2551      // Clean up the visitors we used.
2552      llvm::DeleteContainerPointers(visitors);
2553
2554      // Did anything change while generating this path?
2555      finalReportConfigToken = R->getConfigurationChangeToken();
2556    } while (finalReportConfigToken != origReportConfigToken);
2557
2558    if (!R->isValid())
2559      continue;
2560
2561    // Finally, prune the diagnostic path of uninteresting stuff.
2562    if (!PD.path.empty()) {
2563      // Remove messages that are basically the same.
2564      removeRedundantMsgs(PD.getMutablePieces());
2565
2566      if (R->shouldPrunePath() &&
2567          getEngine().getAnalysisManager().options.shouldPrunePaths()) {
2568        bool stillHasNotes = removeUnneededCalls(PD.getMutablePieces(), R, LCM);
2569        assert(stillHasNotes);
2570        (void)stillHasNotes;
2571      }
2572
2573      adjustCallLocations(PD.getMutablePieces());
2574
2575      if (ActiveScheme == PathDiagnosticConsumer::AlternateExtensive) {
2576        while (optimizeEdges(PD.getMutablePieces(), LCM)) {}
2577      }
2578    }
2579
2580    // We found a report and didn't suppress it.
2581    return true;
2582  }
2583
2584  // We suppressed all the reports in this equivalence class.
2585  assert(!HasInvalid && "Inconsistent suppression");
2586  (void)HasInvalid;
2587  return false;
2588}
2589
2590void BugReporter::Register(BugType *BT) {
2591  BugTypes = F.add(BugTypes, BT);
2592}
2593
2594void BugReporter::emitReport(BugReport* R) {
2595  // Compute the bug report's hash to determine its equivalence class.
2596  llvm::FoldingSetNodeID ID;
2597  R->Profile(ID);
2598
2599  // Lookup the equivance class.  If there isn't one, create it.
2600  BugType& BT = R->getBugType();
2601  Register(&BT);
2602  void *InsertPos;
2603  BugReportEquivClass* EQ = EQClasses.FindNodeOrInsertPos(ID, InsertPos);
2604
2605  if (!EQ) {
2606    EQ = new BugReportEquivClass(R);
2607    EQClasses.InsertNode(EQ, InsertPos);
2608    EQClassesVector.push_back(EQ);
2609  }
2610  else
2611    EQ->AddReport(R);
2612}
2613
2614
2615//===----------------------------------------------------------------------===//
2616// Emitting reports in equivalence classes.
2617//===----------------------------------------------------------------------===//
2618
2619namespace {
2620struct FRIEC_WLItem {
2621  const ExplodedNode *N;
2622  ExplodedNode::const_succ_iterator I, E;
2623
2624  FRIEC_WLItem(const ExplodedNode *n)
2625  : N(n), I(N->succ_begin()), E(N->succ_end()) {}
2626};
2627}
2628
2629static BugReport *
2630FindReportInEquivalenceClass(BugReportEquivClass& EQ,
2631                             SmallVectorImpl<BugReport*> &bugReports) {
2632
2633  BugReportEquivClass::iterator I = EQ.begin(), E = EQ.end();
2634  assert(I != E);
2635  BugType& BT = I->getBugType();
2636
2637  // If we don't need to suppress any of the nodes because they are
2638  // post-dominated by a sink, simply add all the nodes in the equivalence class
2639  // to 'Nodes'.  Any of the reports will serve as a "representative" report.
2640  if (!BT.isSuppressOnSink()) {
2641    BugReport *R = I;
2642    for (BugReportEquivClass::iterator I=EQ.begin(), E=EQ.end(); I!=E; ++I) {
2643      const ExplodedNode *N = I->getErrorNode();
2644      if (N) {
2645        R = I;
2646        bugReports.push_back(R);
2647      }
2648    }
2649    return R;
2650  }
2651
2652  // For bug reports that should be suppressed when all paths are post-dominated
2653  // by a sink node, iterate through the reports in the equivalence class
2654  // until we find one that isn't post-dominated (if one exists).  We use a
2655  // DFS traversal of the ExplodedGraph to find a non-sink node.  We could write
2656  // this as a recursive function, but we don't want to risk blowing out the
2657  // stack for very long paths.
2658  BugReport *exampleReport = 0;
2659
2660  for (; I != E; ++I) {
2661    const ExplodedNode *errorNode = I->getErrorNode();
2662
2663    if (!errorNode)
2664      continue;
2665    if (errorNode->isSink()) {
2666      llvm_unreachable(
2667           "BugType::isSuppressSink() should not be 'true' for sink end nodes");
2668    }
2669    // No successors?  By definition this nodes isn't post-dominated by a sink.
2670    if (errorNode->succ_empty()) {
2671      bugReports.push_back(I);
2672      if (!exampleReport)
2673        exampleReport = I;
2674      continue;
2675    }
2676
2677    // At this point we know that 'N' is not a sink and it has at least one
2678    // successor.  Use a DFS worklist to find a non-sink end-of-path node.
2679    typedef FRIEC_WLItem WLItem;
2680    typedef SmallVector<WLItem, 10> DFSWorkList;
2681    llvm::DenseMap<const ExplodedNode *, unsigned> Visited;
2682
2683    DFSWorkList WL;
2684    WL.push_back(errorNode);
2685    Visited[errorNode] = 1;
2686
2687    while (!WL.empty()) {
2688      WLItem &WI = WL.back();
2689      assert(!WI.N->succ_empty());
2690
2691      for (; WI.I != WI.E; ++WI.I) {
2692        const ExplodedNode *Succ = *WI.I;
2693        // End-of-path node?
2694        if (Succ->succ_empty()) {
2695          // If we found an end-of-path node that is not a sink.
2696          if (!Succ->isSink()) {
2697            bugReports.push_back(I);
2698            if (!exampleReport)
2699              exampleReport = I;
2700            WL.clear();
2701            break;
2702          }
2703          // Found a sink?  Continue on to the next successor.
2704          continue;
2705        }
2706        // Mark the successor as visited.  If it hasn't been explored,
2707        // enqueue it to the DFS worklist.
2708        unsigned &mark = Visited[Succ];
2709        if (!mark) {
2710          mark = 1;
2711          WL.push_back(Succ);
2712          break;
2713        }
2714      }
2715
2716      // The worklist may have been cleared at this point.  First
2717      // check if it is empty before checking the last item.
2718      if (!WL.empty() && &WL.back() == &WI)
2719        WL.pop_back();
2720    }
2721  }
2722
2723  // ExampleReport will be NULL if all the nodes in the equivalence class
2724  // were post-dominated by sinks.
2725  return exampleReport;
2726}
2727
2728void BugReporter::FlushReport(BugReportEquivClass& EQ) {
2729  SmallVector<BugReport*, 10> bugReports;
2730  BugReport *exampleReport = FindReportInEquivalenceClass(EQ, bugReports);
2731  if (exampleReport) {
2732    const PathDiagnosticConsumers &C = getPathDiagnosticConsumers();
2733    for (PathDiagnosticConsumers::const_iterator I=C.begin(),
2734                                                 E=C.end(); I != E; ++I) {
2735      FlushReport(exampleReport, **I, bugReports);
2736    }
2737  }
2738}
2739
2740void BugReporter::FlushReport(BugReport *exampleReport,
2741                              PathDiagnosticConsumer &PD,
2742                              ArrayRef<BugReport*> bugReports) {
2743
2744  // FIXME: Make sure we use the 'R' for the path that was actually used.
2745  // Probably doesn't make a difference in practice.
2746  BugType& BT = exampleReport->getBugType();
2747
2748  OwningPtr<PathDiagnostic>
2749    D(new PathDiagnostic(exampleReport->getDeclWithIssue(),
2750                         exampleReport->getBugType().getName(),
2751                         exampleReport->getDescription(),
2752                         exampleReport->getShortDescription(/*Fallback=*/false),
2753                         BT.getCategory(),
2754                         exampleReport->getUniqueingLocation(),
2755                         exampleReport->getUniqueingDecl()));
2756
2757  MaxBugClassSize = std::max(bugReports.size(),
2758                             static_cast<size_t>(MaxBugClassSize));
2759
2760  // Generate the full path diagnostic, using the generation scheme
2761  // specified by the PathDiagnosticConsumer. Note that we have to generate
2762  // path diagnostics even for consumers which do not support paths, because
2763  // the BugReporterVisitors may mark this bug as a false positive.
2764  if (!bugReports.empty())
2765    if (!generatePathDiagnostic(*D.get(), PD, bugReports))
2766      return;
2767
2768  MaxValidBugClassSize = std::max(bugReports.size(),
2769                                  static_cast<size_t>(MaxValidBugClassSize));
2770
2771  // If the path is empty, generate a single step path with the location
2772  // of the issue.
2773  if (D->path.empty()) {
2774    PathDiagnosticLocation L = exampleReport->getLocation(getSourceManager());
2775    PathDiagnosticPiece *piece =
2776      new PathDiagnosticEventPiece(L, exampleReport->getDescription());
2777    BugReport::ranges_iterator Beg, End;
2778    llvm::tie(Beg, End) = exampleReport->getRanges();
2779    for ( ; Beg != End; ++Beg)
2780      piece->addRange(*Beg);
2781    D->setEndOfPath(piece);
2782  }
2783
2784  // Get the meta data.
2785  const BugReport::ExtraTextList &Meta = exampleReport->getExtraText();
2786  for (BugReport::ExtraTextList::const_iterator i = Meta.begin(),
2787                                                e = Meta.end(); i != e; ++i) {
2788    D->addMeta(*i);
2789  }
2790
2791  PD.HandlePathDiagnostic(D.take());
2792}
2793
2794void BugReporter::EmitBasicReport(const Decl *DeclWithIssue,
2795                                  StringRef name,
2796                                  StringRef category,
2797                                  StringRef str, PathDiagnosticLocation Loc,
2798                                  SourceRange* RBeg, unsigned NumRanges) {
2799
2800  // 'BT' is owned by BugReporter.
2801  BugType *BT = getBugTypeForName(name, category);
2802  BugReport *R = new BugReport(*BT, str, Loc);
2803  R->setDeclWithIssue(DeclWithIssue);
2804  for ( ; NumRanges > 0 ; --NumRanges, ++RBeg) R->addRange(*RBeg);
2805  emitReport(R);
2806}
2807
2808BugType *BugReporter::getBugTypeForName(StringRef name,
2809                                        StringRef category) {
2810  SmallString<136> fullDesc;
2811  llvm::raw_svector_ostream(fullDesc) << name << ":" << category;
2812  llvm::StringMapEntry<BugType *> &
2813      entry = StrBugTypes.GetOrCreateValue(fullDesc);
2814  BugType *BT = entry.getValue();
2815  if (!BT) {
2816    BT = new BugType(name, category);
2817    entry.setValue(BT);
2818  }
2819  return BT;
2820}
2821