BugReporter.cpp revision 220ac8c175cb1bf9b18d82eefe036995d7a2164d 
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#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
16#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
17#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
18#include "clang/AST/ASTContext.h"
19#include "clang/Analysis/CFG.h"
20#include "clang/AST/Expr.h"
21#include "clang/AST/ParentMap.h"
22#include "clang/AST/StmtObjC.h"
23#include "clang/Basic/SourceManager.h"
24#include "clang/Analysis/ProgramPoint.h"
25#include "clang/StaticAnalyzer/Core/BugReporter/PathDiagnostic.h"
26#include "llvm/Support/raw_ostream.h"
27#include "llvm/ADT/DenseMap.h"
28#include "llvm/ADT/STLExtras.h"
29#include "llvm/ADT/OwningPtr.h"
30#include <queue>
31
32using namespace clang;
33using namespace ento;
34
35BugReporterVisitor::~BugReporterVisitor() {}
36
37//===----------------------------------------------------------------------===//
38// Helper routines for walking the ExplodedGraph and fetching statements.
39//===----------------------------------------------------------------------===//
40
41static inline const Stmt *GetStmt(const ProgramPoint &P) {
42  if (const StmtPoint* SP = dyn_cast<StmtPoint>(&P))
43    return SP->getStmt();
44  else if (const BlockEdge *BE = dyn_cast<BlockEdge>(&P))
45    return BE->getSrc()->getTerminator();
46
47  return 0;
48}
49
50static inline const ExplodedNode*
51GetPredecessorNode(const ExplodedNode *N) {
52  return N->pred_empty() ? NULL : *(N->pred_begin());
53}
54
55static inline const ExplodedNode*
56GetSuccessorNode(const ExplodedNode *N) {
57  return N->succ_empty() ? NULL : *(N->succ_begin());
58}
59
60static const Stmt *GetPreviousStmt(const ExplodedNode *N) {
61  for (N = GetPredecessorNode(N); N; N = GetPredecessorNode(N))
62    if (const Stmt *S = GetStmt(N->getLocation()))
63      return S;
64
65  return 0;
66}
67
68static const Stmt *GetNextStmt(const ExplodedNode *N) {
69  for (N = GetSuccessorNode(N); N; N = GetSuccessorNode(N))
70    if (const Stmt *S = GetStmt(N->getLocation())) {
71      // Check if the statement is '?' or '&&'/'||'.  These are "merges",
72      // not actual statement points.
73      switch (S->getStmtClass()) {
74        case Stmt::ChooseExprClass:
75        case Stmt::BinaryConditionalOperatorClass: continue;
76        case Stmt::ConditionalOperatorClass: continue;
77        case Stmt::BinaryOperatorClass: {
78          BinaryOperatorKind Op = cast<BinaryOperator>(S)->getOpcode();
79          if (Op == BO_LAnd || Op == BO_LOr)
80            continue;
81          break;
82        }
83        default:
84          break;
85      }
86      return S;
87    }
88
89  return 0;
90}
91
92static inline const Stmt*
93GetCurrentOrPreviousStmt(const ExplodedNode *N) {
94  if (const Stmt *S = GetStmt(N->getLocation()))
95    return S;
96
97  return GetPreviousStmt(N);
98}
99
100static inline const Stmt*
101GetCurrentOrNextStmt(const ExplodedNode *N) {
102  if (const Stmt *S = GetStmt(N->getLocation()))
103    return S;
104
105  return GetNextStmt(N);
106}
107
108//===----------------------------------------------------------------------===//
109// PathDiagnosticBuilder and its associated routines and helper objects.
110//===----------------------------------------------------------------------===//
111
112typedef llvm::DenseMap<const ExplodedNode*,
113const ExplodedNode*> NodeBackMap;
114
115namespace {
116class NodeMapClosure : public BugReport::NodeResolver {
117  NodeBackMap& M;
118public:
119  NodeMapClosure(NodeBackMap *m) : M(*m) {}
120  ~NodeMapClosure() {}
121
122  const ExplodedNode *getOriginalNode(const ExplodedNode *N) {
123    NodeBackMap::iterator I = M.find(N);
124    return I == M.end() ? 0 : I->second;
125  }
126};
127
128class PathDiagnosticBuilder : public BugReporterContext {
129  BugReport *R;
130  PathDiagnosticClient *PDC;
131  llvm::OwningPtr<ParentMap> PM;
132  NodeMapClosure NMC;
133public:
134  PathDiagnosticBuilder(GRBugReporter &br,
135                        BugReport *r, NodeBackMap *Backmap,
136                        PathDiagnosticClient *pdc)
137    : BugReporterContext(br),
138      R(r), PDC(pdc), NMC(Backmap) {}
139
140  PathDiagnosticLocation ExecutionContinues(const ExplodedNode *N);
141
142  PathDiagnosticLocation ExecutionContinues(llvm::raw_string_ostream &os,
143                                            const ExplodedNode *N);
144
145  BugReport *getBugReport() { return R; }
146
147  Decl const &getCodeDecl() { return R->getErrorNode()->getCodeDecl(); }
148
149  const LocationContext* getLocationContext() {
150    return R->getErrorNode()->getLocationContext();
151  }
152
153  ParentMap& getParentMap() { return R->getErrorNode()->getParentMap(); }
154
155  const Stmt *getParent(const Stmt *S) {
156    return getParentMap().getParent(S);
157  }
158
159  virtual NodeMapClosure& getNodeResolver() { return NMC; }
160
161  PathDiagnosticLocation getEnclosingStmtLocation(const Stmt *S);
162
163  PathDiagnosticClient::PathGenerationScheme getGenerationScheme() const {
164    return PDC ? PDC->getGenerationScheme() : PathDiagnosticClient::Extensive;
165  }
166
167  bool supportsLogicalOpControlFlow() const {
168    return PDC ? PDC->supportsLogicalOpControlFlow() : true;
169  }
170};
171} // end anonymous namespace
172
173PathDiagnosticLocation
174PathDiagnosticBuilder::ExecutionContinues(const ExplodedNode *N) {
175  if (const Stmt *S = GetNextStmt(N))
176    return PathDiagnosticLocation(S, getSourceManager(), getLocationContext());
177
178  return FullSourceLoc(N->getLocationContext()->getDecl()->getBodyRBrace(),
179                       getSourceManager());
180}
181
182PathDiagnosticLocation
183PathDiagnosticBuilder::ExecutionContinues(llvm::raw_string_ostream &os,
184                                          const ExplodedNode *N) {
185
186  // Slow, but probably doesn't matter.
187  if (os.str().empty())
188    os << ' ';
189
190  const PathDiagnosticLocation &Loc = ExecutionContinues(N);
191
192  if (Loc.asStmt())
193    os << "Execution continues on line "
194       << getSourceManager().getExpansionLineNumber(Loc.asLocation())
195       << '.';
196  else {
197    os << "Execution jumps to the end of the ";
198    const Decl *D = N->getLocationContext()->getDecl();
199    if (isa<ObjCMethodDecl>(D))
200      os << "method";
201    else if (isa<FunctionDecl>(D))
202      os << "function";
203    else {
204      assert(isa<BlockDecl>(D));
205      os << "anonymous block";
206    }
207    os << '.';
208  }
209
210  return Loc;
211}
212
213static bool IsNested(const Stmt *S, ParentMap &PM) {
214  if (isa<Expr>(S) && PM.isConsumedExpr(cast<Expr>(S)))
215    return true;
216
217  const Stmt *Parent = PM.getParentIgnoreParens(S);
218
219  if (Parent)
220    switch (Parent->getStmtClass()) {
221      case Stmt::ForStmtClass:
222      case Stmt::DoStmtClass:
223      case Stmt::WhileStmtClass:
224        return true;
225      default:
226        break;
227    }
228
229  return false;
230}
231
232PathDiagnosticLocation
233PathDiagnosticBuilder::getEnclosingStmtLocation(const Stmt *S) {
234  assert(S && "Null Stmt *passed to getEnclosingStmtLocation");
235  ParentMap &P = getParentMap();
236  SourceManager &SMgr = getSourceManager();
237  const LocationContext *LC = getLocationContext();
238
239  while (IsNested(S, P)) {
240    const Stmt *Parent = P.getParentIgnoreParens(S);
241
242    if (!Parent)
243      break;
244
245    switch (Parent->getStmtClass()) {
246      case Stmt::BinaryOperatorClass: {
247        const BinaryOperator *B = cast<BinaryOperator>(Parent);
248        if (B->isLogicalOp())
249          return PathDiagnosticLocation(S, SMgr, LC);
250        break;
251      }
252      case Stmt::CompoundStmtClass:
253      case Stmt::StmtExprClass:
254        return PathDiagnosticLocation(S, SMgr, LC);
255      case Stmt::ChooseExprClass:
256        // Similar to '?' if we are referring to condition, just have the edge
257        // point to the entire choose expression.
258        if (cast<ChooseExpr>(Parent)->getCond() == S)
259          return PathDiagnosticLocation(Parent, SMgr, LC);
260        else
261          return PathDiagnosticLocation(S, SMgr, LC);
262      case Stmt::BinaryConditionalOperatorClass:
263      case Stmt::ConditionalOperatorClass:
264        // For '?', if we are referring to condition, just have the edge point
265        // to the entire '?' expression.
266        if (cast<AbstractConditionalOperator>(Parent)->getCond() == S)
267          return PathDiagnosticLocation(Parent, SMgr, LC);
268        else
269          return PathDiagnosticLocation(S, SMgr, LC);
270      case Stmt::DoStmtClass:
271          return PathDiagnosticLocation(S, SMgr, LC);
272      case Stmt::ForStmtClass:
273        if (cast<ForStmt>(Parent)->getBody() == S)
274          return PathDiagnosticLocation(S, SMgr, LC);
275        break;
276      case Stmt::IfStmtClass:
277        if (cast<IfStmt>(Parent)->getCond() != S)
278          return PathDiagnosticLocation(S, SMgr, LC);
279        break;
280      case Stmt::ObjCForCollectionStmtClass:
281        if (cast<ObjCForCollectionStmt>(Parent)->getBody() == S)
282          return PathDiagnosticLocation(S, SMgr, LC);
283        break;
284      case Stmt::WhileStmtClass:
285        if (cast<WhileStmt>(Parent)->getCond() != S)
286          return PathDiagnosticLocation(S, SMgr, LC);
287        break;
288      default:
289        break;
290    }
291
292    S = Parent;
293  }
294
295  assert(S && "Cannot have null Stmt for PathDiagnosticLocation");
296
297  // Special case: DeclStmts can appear in for statement declarations, in which
298  //  case the ForStmt is the context.
299  if (isa<DeclStmt>(S)) {
300    if (const Stmt *Parent = P.getParent(S)) {
301      switch (Parent->getStmtClass()) {
302        case Stmt::ForStmtClass:
303        case Stmt::ObjCForCollectionStmtClass:
304          return PathDiagnosticLocation(Parent, SMgr, LC);
305        default:
306          break;
307      }
308    }
309  }
310  else if (isa<BinaryOperator>(S)) {
311    // Special case: the binary operator represents the initialization
312    // code in a for statement (this can happen when the variable being
313    // initialized is an old variable.
314    if (const ForStmt *FS =
315          dyn_cast_or_null<ForStmt>(P.getParentIgnoreParens(S))) {
316      if (FS->getInit() == S)
317        return PathDiagnosticLocation(FS, SMgr, LC);
318    }
319  }
320
321  return PathDiagnosticLocation(S, SMgr, LC);
322}
323
324//===----------------------------------------------------------------------===//
325// ScanNotableSymbols: closure-like callback for scanning Store bindings.
326//===----------------------------------------------------------------------===//
327
328static const VarDecl* GetMostRecentVarDeclBinding(const ExplodedNode *N,
329                                                  ProgramStateManager& VMgr,
330                                                  SVal X) {
331
332  for ( ; N ; N = N->pred_empty() ? 0 : *N->pred_begin()) {
333
334    ProgramPoint P = N->getLocation();
335
336    if (!isa<PostStmt>(P))
337      continue;
338
339    const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(cast<PostStmt>(P).getStmt());
340
341    if (!DR)
342      continue;
343
344    SVal Y = N->getState()->getSVal(DR);
345
346    if (X != Y)
347      continue;
348
349    const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
350
351    if (!VD)
352      continue;
353
354    return VD;
355  }
356
357  return 0;
358}
359
360namespace {
361class NotableSymbolHandler
362: public StoreManager::BindingsHandler {
363
364  SymbolRef Sym;
365  const ProgramState *PrevSt;
366  const Stmt *S;
367  ProgramStateManager& VMgr;
368  const ExplodedNode *Pred;
369  PathDiagnostic& PD;
370  BugReporter& BR;
371
372public:
373
374  NotableSymbolHandler(SymbolRef sym,
375                       const ProgramState *prevst,
376                       const Stmt *s,
377                       ProgramStateManager& vmgr,
378                       const ExplodedNode *pred,
379                       PathDiagnostic& pd,
380                       BugReporter& br)
381  : Sym(sym),
382    PrevSt(prevst),
383    S(s),
384    VMgr(vmgr),
385    Pred(pred),
386    PD(pd),
387    BR(br) {}
388
389  bool HandleBinding(StoreManager& SMgr, Store store, const MemRegion* R,
390                     SVal V) {
391
392    SymbolRef ScanSym = V.getAsSymbol();
393
394    if (ScanSym != Sym)
395      return true;
396
397    // Check if the previous state has this binding.
398    SVal X = PrevSt->getSVal(loc::MemRegionVal(R));
399
400    if (X == V) // Same binding?
401      return true;
402
403    // Different binding.  Only handle assignments for now.  We don't pull
404    // this check out of the loop because we will eventually handle other
405    // cases.
406
407    VarDecl *VD = 0;
408
409    if (const BinaryOperator* B = dyn_cast<BinaryOperator>(S)) {
410      if (!B->isAssignmentOp())
411        return true;
412
413      // What variable did we assign to?
414      DeclRefExpr *DR = dyn_cast<DeclRefExpr>(B->getLHS()->IgnoreParenCasts());
415
416      if (!DR)
417        return true;
418
419      VD = dyn_cast<VarDecl>(DR->getDecl());
420    }
421    else if (const DeclStmt *DS = dyn_cast<DeclStmt>(S)) {
422      // FIXME: Eventually CFGs won't have DeclStmts.  Right now we
423      //  assume that each DeclStmt has a single Decl.  This invariant
424      //  holds by construction in the CFG.
425      VD = dyn_cast<VarDecl>(*DS->decl_begin());
426    }
427
428    if (!VD)
429      return true;
430
431    // What is the most recently referenced variable with this binding?
432    const VarDecl *MostRecent = GetMostRecentVarDeclBinding(Pred, VMgr, V);
433
434    if (!MostRecent)
435      return true;
436
437    // Create the diagnostic.
438    FullSourceLoc L(S->getLocStart(), BR.getSourceManager());
439
440    if (Loc::isLocType(VD->getType())) {
441      llvm::SmallString<64> buf;
442      llvm::raw_svector_ostream os(buf);
443      os << '\'' << VD << "' now aliases '" << MostRecent << '\'';
444
445      PD.push_front(new PathDiagnosticEventPiece(L, os.str()));
446    }
447
448    return true;
449  }
450};
451}
452
453static void HandleNotableSymbol(const ExplodedNode *N,
454                                const Stmt *S,
455                                SymbolRef Sym, BugReporter& BR,
456                                PathDiagnostic& PD) {
457
458  const ExplodedNode *Pred = N->pred_empty() ? 0 : *N->pred_begin();
459  const ProgramState *PrevSt = Pred ? Pred->getState() : 0;
460
461  if (!PrevSt)
462    return;
463
464  // Look at the region bindings of the current state that map to the
465  // specified symbol.  Are any of them not in the previous state?
466  ProgramStateManager& VMgr = cast<GRBugReporter>(BR).getStateManager();
467  NotableSymbolHandler H(Sym, PrevSt, S, VMgr, Pred, PD, BR);
468  cast<GRBugReporter>(BR).getStateManager().iterBindings(N->getState(), H);
469}
470
471namespace {
472class ScanNotableSymbols
473: public StoreManager::BindingsHandler {
474
475  llvm::SmallSet<SymbolRef, 10> AlreadyProcessed;
476  const ExplodedNode *N;
477  const Stmt *S;
478  GRBugReporter& BR;
479  PathDiagnostic& PD;
480
481public:
482  ScanNotableSymbols(const ExplodedNode *n, const Stmt *s,
483                     GRBugReporter& br, PathDiagnostic& pd)
484  : N(n), S(s), BR(br), PD(pd) {}
485
486  bool HandleBinding(StoreManager& SMgr, Store store,
487                     const MemRegion* R, SVal V) {
488
489    SymbolRef ScanSym = V.getAsSymbol();
490
491    if (!ScanSym)
492      return true;
493
494    if (!BR.isNotable(ScanSym))
495      return true;
496
497    if (AlreadyProcessed.count(ScanSym))
498      return true;
499
500    AlreadyProcessed.insert(ScanSym);
501
502    HandleNotableSymbol(N, S, ScanSym, BR, PD);
503    return true;
504  }
505};
506} // end anonymous namespace
507
508//===----------------------------------------------------------------------===//
509// "Minimal" path diagnostic generation algorithm.
510//===----------------------------------------------------------------------===//
511
512static void CompactPathDiagnostic(PathDiagnostic &PD, const SourceManager& SM);
513
514static void GenerateMinimalPathDiagnostic(PathDiagnostic& PD,
515                                          PathDiagnosticBuilder &PDB,
516                                          const ExplodedNode *N) {
517
518  SourceManager& SMgr = PDB.getSourceManager();
519  const LocationContext *LC = PDB.getLocationContext();
520  const ExplodedNode *NextNode = N->pred_empty()
521                                        ? NULL : *(N->pred_begin());
522  while (NextNode) {
523    N = NextNode;
524    NextNode = GetPredecessorNode(N);
525
526    ProgramPoint P = N->getLocation();
527
528    if (const BlockEdge *BE = dyn_cast<BlockEdge>(&P)) {
529      const CFGBlock *Src = BE->getSrc();
530      const CFGBlock *Dst = BE->getDst();
531      const Stmt *T = Src->getTerminator();
532
533      if (!T)
534        continue;
535
536      FullSourceLoc Start(T->getLocStart(), SMgr);
537
538      switch (T->getStmtClass()) {
539        default:
540          break;
541
542        case Stmt::GotoStmtClass:
543        case Stmt::IndirectGotoStmtClass: {
544          const Stmt *S = GetNextStmt(N);
545
546          if (!S)
547            continue;
548
549          std::string sbuf;
550          llvm::raw_string_ostream os(sbuf);
551          const PathDiagnosticLocation &End = PDB.getEnclosingStmtLocation(S);
552
553          os << "Control jumps to line "
554          << End.asLocation().getExpansionLineNumber();
555          PD.push_front(new PathDiagnosticControlFlowPiece(Start, End,
556                                                           os.str()));
557          break;
558        }
559
560        case Stmt::SwitchStmtClass: {
561          // Figure out what case arm we took.
562          std::string sbuf;
563          llvm::raw_string_ostream os(sbuf);
564
565          if (const Stmt *S = Dst->getLabel()) {
566            PathDiagnosticLocation End(S, SMgr, LC);
567
568            switch (S->getStmtClass()) {
569              default:
570                os << "No cases match in the switch statement. "
571                "Control jumps to line "
572                << End.asLocation().getExpansionLineNumber();
573                break;
574              case Stmt::DefaultStmtClass:
575                os << "Control jumps to the 'default' case at line "
576                << End.asLocation().getExpansionLineNumber();
577                break;
578
579              case Stmt::CaseStmtClass: {
580                os << "Control jumps to 'case ";
581                const CaseStmt *Case = cast<CaseStmt>(S);
582                const Expr *LHS = Case->getLHS()->IgnoreParenCasts();
583
584                // Determine if it is an enum.
585                bool GetRawInt = true;
586
587                if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(LHS)) {
588                  // FIXME: Maybe this should be an assertion.  Are there cases
589                  // were it is not an EnumConstantDecl?
590                  const EnumConstantDecl *D =
591                    dyn_cast<EnumConstantDecl>(DR->getDecl());
592
593                  if (D) {
594                    GetRawInt = false;
595                    os << D;
596                  }
597                }
598
599                if (GetRawInt)
600                  os << LHS->EvaluateAsInt(PDB.getASTContext());
601
602                os << ":'  at line "
603                << End.asLocation().getExpansionLineNumber();
604                break;
605              }
606            }
607            PD.push_front(new PathDiagnosticControlFlowPiece(Start, End,
608                                                             os.str()));
609          }
610          else {
611            os << "'Default' branch taken. ";
612            const PathDiagnosticLocation &End = PDB.ExecutionContinues(os, N);
613            PD.push_front(new PathDiagnosticControlFlowPiece(Start, End,
614                                                             os.str()));
615          }
616
617          break;
618        }
619
620        case Stmt::BreakStmtClass:
621        case Stmt::ContinueStmtClass: {
622          std::string sbuf;
623          llvm::raw_string_ostream os(sbuf);
624          PathDiagnosticLocation End = PDB.ExecutionContinues(os, N);
625          PD.push_front(new PathDiagnosticControlFlowPiece(Start, End,
626                                                           os.str()));
627          break;
628        }
629
630          // Determine control-flow for ternary '?'.
631        case Stmt::BinaryConditionalOperatorClass:
632        case Stmt::ConditionalOperatorClass: {
633          std::string sbuf;
634          llvm::raw_string_ostream os(sbuf);
635          os << "'?' condition is ";
636
637          if (*(Src->succ_begin()+1) == Dst)
638            os << "false";
639          else
640            os << "true";
641
642          PathDiagnosticLocation End = PDB.ExecutionContinues(N);
643
644          if (const Stmt *S = End.asStmt())
645            End = PDB.getEnclosingStmtLocation(S);
646
647          PD.push_front(new PathDiagnosticControlFlowPiece(Start, End,
648                                                           os.str()));
649          break;
650        }
651
652          // Determine control-flow for short-circuited '&&' and '||'.
653        case Stmt::BinaryOperatorClass: {
654          if (!PDB.supportsLogicalOpControlFlow())
655            break;
656
657          const BinaryOperator *B = cast<BinaryOperator>(T);
658          std::string sbuf;
659          llvm::raw_string_ostream os(sbuf);
660          os << "Left side of '";
661
662          if (B->getOpcode() == BO_LAnd) {
663            os << "&&" << "' is ";
664
665            if (*(Src->succ_begin()+1) == Dst) {
666              os << "false";
667              PathDiagnosticLocation End(B->getLHS(), SMgr, LC);
668              PathDiagnosticLocation Start(B->getOperatorLoc(), SMgr);
669              PD.push_front(new PathDiagnosticControlFlowPiece(Start, End,
670                                                               os.str()));
671            }
672            else {
673              os << "true";
674              PathDiagnosticLocation Start(B->getLHS(), SMgr, LC);
675              PathDiagnosticLocation End = PDB.ExecutionContinues(N);
676              PD.push_front(new PathDiagnosticControlFlowPiece(Start, End,
677                                                               os.str()));
678            }
679          }
680          else {
681            assert(B->getOpcode() == BO_LOr);
682            os << "||" << "' is ";
683
684            if (*(Src->succ_begin()+1) == Dst) {
685              os << "false";
686              PathDiagnosticLocation Start(B->getLHS(), SMgr, LC);
687              PathDiagnosticLocation End = PDB.ExecutionContinues(N);
688              PD.push_front(new PathDiagnosticControlFlowPiece(Start, End,
689                                                               os.str()));
690            }
691            else {
692              os << "true";
693              PathDiagnosticLocation End(B->getLHS(), SMgr, LC);
694              PathDiagnosticLocation Start(B->getOperatorLoc(), SMgr);
695              PD.push_front(new PathDiagnosticControlFlowPiece(Start, End,
696                                                               os.str()));
697            }
698          }
699
700          break;
701        }
702
703        case Stmt::DoStmtClass:  {
704          if (*(Src->succ_begin()) == Dst) {
705            std::string sbuf;
706            llvm::raw_string_ostream os(sbuf);
707
708            os << "Loop condition is true. ";
709            PathDiagnosticLocation End = PDB.ExecutionContinues(os, N);
710
711            if (const Stmt *S = End.asStmt())
712              End = PDB.getEnclosingStmtLocation(S);
713
714            PD.push_front(new PathDiagnosticControlFlowPiece(Start, End,
715                                                             os.str()));
716          }
717          else {
718            PathDiagnosticLocation End = PDB.ExecutionContinues(N);
719
720            if (const Stmt *S = End.asStmt())
721              End = PDB.getEnclosingStmtLocation(S);
722
723            PD.push_front(new PathDiagnosticControlFlowPiece(Start, End,
724                              "Loop condition is false.  Exiting loop"));
725          }
726
727          break;
728        }
729
730        case Stmt::WhileStmtClass:
731        case Stmt::ForStmtClass: {
732          if (*(Src->succ_begin()+1) == Dst) {
733            std::string sbuf;
734            llvm::raw_string_ostream os(sbuf);
735
736            os << "Loop condition is false. ";
737            PathDiagnosticLocation End = PDB.ExecutionContinues(os, N);
738            if (const Stmt *S = End.asStmt())
739              End = PDB.getEnclosingStmtLocation(S);
740
741            PD.push_front(new PathDiagnosticControlFlowPiece(Start, End,
742                                                             os.str()));
743          }
744          else {
745            PathDiagnosticLocation End = PDB.ExecutionContinues(N);
746            if (const Stmt *S = End.asStmt())
747              End = PDB.getEnclosingStmtLocation(S);
748
749            PD.push_front(new PathDiagnosticControlFlowPiece(Start, End,
750                            "Loop condition is true.  Entering loop body"));
751          }
752
753          break;
754        }
755
756        case Stmt::IfStmtClass: {
757          PathDiagnosticLocation End = PDB.ExecutionContinues(N);
758
759          if (const Stmt *S = End.asStmt())
760            End = PDB.getEnclosingStmtLocation(S);
761
762          if (*(Src->succ_begin()+1) == Dst)
763            PD.push_front(new PathDiagnosticControlFlowPiece(Start, End,
764                                                        "Taking false branch"));
765          else
766            PD.push_front(new PathDiagnosticControlFlowPiece(Start, End,
767                                                         "Taking true branch"));
768
769          break;
770        }
771      }
772    }
773
774    if (NextNode) {
775      // Add diagnostic pieces from custom visitors.
776      BugReport *R = PDB.getBugReport();
777      for (BugReport::visitor_iterator I = R->visitor_begin(),
778           E = R->visitor_end(); I!=E; ++I) {
779        if (PathDiagnosticPiece *p = (*I)->VisitNode(N, NextNode, PDB, *R))
780          PD.push_front(p);
781      }
782    }
783
784    if (const PostStmt *PS = dyn_cast<PostStmt>(&P)) {
785      // Scan the region bindings, and see if a "notable" symbol has a new
786      // lval binding.
787      ScanNotableSymbols SNS(N, PS->getStmt(), PDB.getBugReporter(), PD);
788      PDB.getStateManager().iterBindings(N->getState(), SNS);
789    }
790  }
791
792  // After constructing the full PathDiagnostic, do a pass over it to compact
793  // PathDiagnosticPieces that occur within a macro.
794  CompactPathDiagnostic(PD, PDB.getSourceManager());
795}
796
797//===----------------------------------------------------------------------===//
798// "Extensive" PathDiagnostic generation.
799//===----------------------------------------------------------------------===//
800
801static bool IsControlFlowExpr(const Stmt *S) {
802  const Expr *E = dyn_cast<Expr>(S);
803
804  if (!E)
805    return false;
806
807  E = E->IgnoreParenCasts();
808
809  if (isa<AbstractConditionalOperator>(E))
810    return true;
811
812  if (const BinaryOperator *B = dyn_cast<BinaryOperator>(E))
813    if (B->isLogicalOp())
814      return true;
815
816  return false;
817}
818
819namespace {
820class ContextLocation : public PathDiagnosticLocation {
821  bool IsDead;
822public:
823  ContextLocation(const PathDiagnosticLocation &L, bool isdead = false)
824    : PathDiagnosticLocation(L), IsDead(isdead) {}
825
826  void markDead() { IsDead = true; }
827  bool isDead() const { return IsDead; }
828};
829
830class EdgeBuilder {
831  std::vector<ContextLocation> CLocs;
832  typedef std::vector<ContextLocation>::iterator iterator;
833  PathDiagnostic &PD;
834  PathDiagnosticBuilder &PDB;
835  PathDiagnosticLocation PrevLoc;
836
837  bool IsConsumedExpr(const PathDiagnosticLocation &L);
838
839  bool containsLocation(const PathDiagnosticLocation &Container,
840                        const PathDiagnosticLocation &Containee);
841
842  PathDiagnosticLocation getContextLocation(const PathDiagnosticLocation &L);
843
844  PathDiagnosticLocation cleanUpLocation(PathDiagnosticLocation L,
845                                         bool firstCharOnly = false) {
846    if (const Stmt *S = L.asStmt()) {
847      const Stmt *Original = S;
848      while (1) {
849        // Adjust the location for some expressions that are best referenced
850        // by one of their subexpressions.
851        switch (S->getStmtClass()) {
852          default:
853            break;
854          case Stmt::ParenExprClass:
855          case Stmt::GenericSelectionExprClass:
856            S = cast<Expr>(S)->IgnoreParens();
857            firstCharOnly = true;
858            continue;
859          case Stmt::BinaryConditionalOperatorClass:
860          case Stmt::ConditionalOperatorClass:
861            S = cast<AbstractConditionalOperator>(S)->getCond();
862            firstCharOnly = true;
863            continue;
864          case Stmt::ChooseExprClass:
865            S = cast<ChooseExpr>(S)->getCond();
866            firstCharOnly = true;
867            continue;
868          case Stmt::BinaryOperatorClass:
869            S = cast<BinaryOperator>(S)->getLHS();
870            firstCharOnly = true;
871            continue;
872        }
873
874        break;
875      }
876
877      if (S != Original)
878        L = PathDiagnosticLocation(S, L.getManager(), L.getLocationContext());
879    }
880
881    if (firstCharOnly)
882      L = PathDiagnosticLocation(L.asLocation());
883
884    return L;
885  }
886
887  void popLocation() {
888    if (!CLocs.back().isDead() && CLocs.back().asLocation().isFileID()) {
889      // For contexts, we only one the first character as the range.
890      rawAddEdge(cleanUpLocation(CLocs.back(), true));
891    }
892    CLocs.pop_back();
893  }
894
895public:
896  EdgeBuilder(PathDiagnostic &pd, PathDiagnosticBuilder &pdb)
897    : PD(pd), PDB(pdb) {
898
899      // If the PathDiagnostic already has pieces, add the enclosing statement
900      // of the first piece as a context as well.
901      if (!PD.empty()) {
902        PrevLoc = PD.begin()->getLocation();
903
904        if (const Stmt *S = PrevLoc.asStmt())
905          addExtendedContext(PDB.getEnclosingStmtLocation(S).asStmt());
906      }
907  }
908
909  ~EdgeBuilder() {
910    while (!CLocs.empty()) popLocation();
911
912    // Finally, add an initial edge from the start location of the first
913    // statement (if it doesn't already exist).
914    // FIXME: Should handle CXXTryStmt if analyser starts supporting C++.
915    if (const CompoundStmt *CS =
916          dyn_cast_or_null<CompoundStmt>(PDB.getCodeDecl().getBody()))
917      if (!CS->body_empty()) {
918        SourceLocation Loc = (*CS->body_begin())->getLocStart();
919        rawAddEdge(PathDiagnosticLocation(Loc, PDB.getSourceManager()));
920      }
921
922  }
923
924  void addEdge(PathDiagnosticLocation NewLoc, bool alwaysAdd = false);
925
926  void rawAddEdge(PathDiagnosticLocation NewLoc);
927
928  void addContext(const Stmt *S);
929  void addExtendedContext(const Stmt *S);
930};
931} // end anonymous namespace
932
933
934PathDiagnosticLocation
935EdgeBuilder::getContextLocation(const PathDiagnosticLocation &L) {
936  if (const Stmt *S = L.asStmt()) {
937    if (IsControlFlowExpr(S))
938      return L;
939
940    return PDB.getEnclosingStmtLocation(S);
941  }
942
943  return L;
944}
945
946bool EdgeBuilder::containsLocation(const PathDiagnosticLocation &Container,
947                                   const PathDiagnosticLocation &Containee) {
948
949  if (Container == Containee)
950    return true;
951
952  if (Container.asDecl())
953    return true;
954
955  if (const Stmt *S = Containee.asStmt())
956    if (const Stmt *ContainerS = Container.asStmt()) {
957      while (S) {
958        if (S == ContainerS)
959          return true;
960        S = PDB.getParent(S);
961      }
962      return false;
963    }
964
965  // Less accurate: compare using source ranges.
966  SourceRange ContainerR = Container.asRange();
967  SourceRange ContaineeR = Containee.asRange();
968
969  SourceManager &SM = PDB.getSourceManager();
970  SourceLocation ContainerRBeg = SM.getExpansionLoc(ContainerR.getBegin());
971  SourceLocation ContainerREnd = SM.getExpansionLoc(ContainerR.getEnd());
972  SourceLocation ContaineeRBeg = SM.getExpansionLoc(ContaineeR.getBegin());
973  SourceLocation ContaineeREnd = SM.getExpansionLoc(ContaineeR.getEnd());
974
975  unsigned ContainerBegLine = SM.getExpansionLineNumber(ContainerRBeg);
976  unsigned ContainerEndLine = SM.getExpansionLineNumber(ContainerREnd);
977  unsigned ContaineeBegLine = SM.getExpansionLineNumber(ContaineeRBeg);
978  unsigned ContaineeEndLine = SM.getExpansionLineNumber(ContaineeREnd);
979
980  assert(ContainerBegLine <= ContainerEndLine);
981  assert(ContaineeBegLine <= ContaineeEndLine);
982
983  return (ContainerBegLine <= ContaineeBegLine &&
984          ContainerEndLine >= ContaineeEndLine &&
985          (ContainerBegLine != ContaineeBegLine ||
986           SM.getExpansionColumnNumber(ContainerRBeg) <=
987           SM.getExpansionColumnNumber(ContaineeRBeg)) &&
988          (ContainerEndLine != ContaineeEndLine ||
989           SM.getExpansionColumnNumber(ContainerREnd) >=
990           SM.getExpansionColumnNumber(ContainerREnd)));
991}
992
993void EdgeBuilder::rawAddEdge(PathDiagnosticLocation NewLoc) {
994  if (!PrevLoc.isValid()) {
995    PrevLoc = NewLoc;
996    return;
997  }
998
999  const PathDiagnosticLocation &NewLocClean = cleanUpLocation(NewLoc);
1000  const PathDiagnosticLocation &PrevLocClean = cleanUpLocation(PrevLoc);
1001
1002  if (NewLocClean.asLocation() == PrevLocClean.asLocation())
1003    return;
1004
1005  // FIXME: Ignore intra-macro edges for now.
1006  if (NewLocClean.asLocation().getExpansionLoc() ==
1007      PrevLocClean.asLocation().getExpansionLoc())
1008    return;
1009
1010  PD.push_front(new PathDiagnosticControlFlowPiece(NewLocClean, PrevLocClean));
1011  PrevLoc = NewLoc;
1012}
1013
1014void EdgeBuilder::addEdge(PathDiagnosticLocation NewLoc, bool alwaysAdd) {
1015
1016  if (!alwaysAdd && NewLoc.asLocation().isMacroID())
1017    return;
1018
1019  const PathDiagnosticLocation &CLoc = getContextLocation(NewLoc);
1020
1021  while (!CLocs.empty()) {
1022    ContextLocation &TopContextLoc = CLocs.back();
1023
1024    // Is the top location context the same as the one for the new location?
1025    if (TopContextLoc == CLoc) {
1026      if (alwaysAdd) {
1027        if (IsConsumedExpr(TopContextLoc) &&
1028            !IsControlFlowExpr(TopContextLoc.asStmt()))
1029            TopContextLoc.markDead();
1030
1031        rawAddEdge(NewLoc);
1032      }
1033
1034      return;
1035    }
1036
1037    if (containsLocation(TopContextLoc, CLoc)) {
1038      if (alwaysAdd) {
1039        rawAddEdge(NewLoc);
1040
1041        if (IsConsumedExpr(CLoc) && !IsControlFlowExpr(CLoc.asStmt())) {
1042          CLocs.push_back(ContextLocation(CLoc, true));
1043          return;
1044        }
1045      }
1046
1047      CLocs.push_back(CLoc);
1048      return;
1049    }
1050
1051    // Context does not contain the location.  Flush it.
1052    popLocation();
1053  }
1054
1055  // If we reach here, there is no enclosing context.  Just add the edge.
1056  rawAddEdge(NewLoc);
1057}
1058
1059bool EdgeBuilder::IsConsumedExpr(const PathDiagnosticLocation &L) {
1060  if (const Expr *X = dyn_cast_or_null<Expr>(L.asStmt()))
1061    return PDB.getParentMap().isConsumedExpr(X) && !IsControlFlowExpr(X);
1062
1063  return false;
1064}
1065
1066void EdgeBuilder::addExtendedContext(const Stmt *S) {
1067  if (!S)
1068    return;
1069
1070  const Stmt *Parent = PDB.getParent(S);
1071  while (Parent) {
1072    if (isa<CompoundStmt>(Parent))
1073      Parent = PDB.getParent(Parent);
1074    else
1075      break;
1076  }
1077
1078  if (Parent) {
1079    switch (Parent->getStmtClass()) {
1080      case Stmt::DoStmtClass:
1081      case Stmt::ObjCAtSynchronizedStmtClass:
1082        addContext(Parent);
1083      default:
1084        break;
1085    }
1086  }
1087
1088  addContext(S);
1089}
1090
1091void EdgeBuilder::addContext(const Stmt *S) {
1092  if (!S)
1093    return;
1094
1095  PathDiagnosticLocation L(S, PDB.getSourceManager(), PDB.getLocationContext());
1096
1097  while (!CLocs.empty()) {
1098    const PathDiagnosticLocation &TopContextLoc = CLocs.back();
1099
1100    // Is the top location context the same as the one for the new location?
1101    if (TopContextLoc == L)
1102      return;
1103
1104    if (containsLocation(TopContextLoc, L)) {
1105      CLocs.push_back(L);
1106      return;
1107    }
1108
1109    // Context does not contain the location.  Flush it.
1110    popLocation();
1111  }
1112
1113  CLocs.push_back(L);
1114}
1115
1116static void GenerateExtensivePathDiagnostic(PathDiagnostic& PD,
1117                                            PathDiagnosticBuilder &PDB,
1118                                            const ExplodedNode *N) {
1119  EdgeBuilder EB(PD, PDB);
1120
1121  const ExplodedNode *NextNode = N->pred_empty() ? NULL : *(N->pred_begin());
1122  while (NextNode) {
1123    N = NextNode;
1124    NextNode = GetPredecessorNode(N);
1125    ProgramPoint P = N->getLocation();
1126
1127    do {
1128      // Block edges.
1129      if (const BlockEdge *BE = dyn_cast<BlockEdge>(&P)) {
1130        const CFGBlock &Blk = *BE->getSrc();
1131        const Stmt *Term = Blk.getTerminator();
1132
1133        // Are we jumping to the head of a loop?  Add a special diagnostic.
1134        if (const Stmt *Loop = BE->getDst()->getLoopTarget()) {
1135          PathDiagnosticLocation L(Loop, PDB.getSourceManager(),
1136                                         PDB.getLocationContext());
1137          const CompoundStmt *CS = NULL;
1138
1139          if (!Term) {
1140            if (const ForStmt *FS = dyn_cast<ForStmt>(Loop))
1141              CS = dyn_cast<CompoundStmt>(FS->getBody());
1142            else if (const WhileStmt *WS = dyn_cast<WhileStmt>(Loop))
1143              CS = dyn_cast<CompoundStmt>(WS->getBody());
1144          }
1145
1146          PathDiagnosticEventPiece *p =
1147            new PathDiagnosticEventPiece(L,
1148                                        "Looping back to the head of the loop");
1149
1150          EB.addEdge(p->getLocation(), true);
1151          PD.push_front(p);
1152
1153          if (CS) {
1154            PathDiagnosticLocation BL(CS->getRBracLoc(),
1155                                      PDB.getSourceManager());
1156            BL = PathDiagnosticLocation(BL.asLocation());
1157            EB.addEdge(BL);
1158          }
1159        }
1160
1161        if (Term)
1162          EB.addContext(Term);
1163
1164        break;
1165      }
1166
1167      if (const BlockEntrance *BE = dyn_cast<BlockEntrance>(&P)) {
1168        if (const CFGStmt *S = BE->getFirstElement().getAs<CFGStmt>()) {
1169          const Stmt *stmt = S->getStmt();
1170          if (IsControlFlowExpr(stmt)) {
1171            // Add the proper context for '&&', '||', and '?'.
1172            EB.addContext(stmt);
1173          }
1174          else
1175            EB.addExtendedContext(PDB.getEnclosingStmtLocation(stmt).asStmt());
1176        }
1177
1178        break;
1179      }
1180    } while (0);
1181
1182    if (!NextNode)
1183      continue;
1184
1185    // Add pieces from custom visitors.
1186    BugReport *R = PDB.getBugReport();
1187    for (BugReport::visitor_iterator I = R->visitor_begin(),
1188                                     E = R->visitor_end(); I!=E; ++I) {
1189      if (PathDiagnosticPiece *p = (*I)->VisitNode(N, NextNode, PDB, *R)) {
1190        const PathDiagnosticLocation &Loc = p->getLocation();
1191        EB.addEdge(Loc, true);
1192        PD.push_front(p);
1193        if (const Stmt *S = Loc.asStmt())
1194          EB.addExtendedContext(PDB.getEnclosingStmtLocation(S).asStmt());
1195      }
1196    }
1197  }
1198}
1199
1200//===----------------------------------------------------------------------===//
1201// Methods for BugType and subclasses.
1202//===----------------------------------------------------------------------===//
1203BugType::~BugType() { }
1204
1205void BugType::FlushReports(BugReporter &BR) {}
1206
1207//===----------------------------------------------------------------------===//
1208// Methods for BugReport and subclasses.
1209//===----------------------------------------------------------------------===//
1210
1211void BugReport::addVisitor(BugReporterVisitor* visitor) {
1212  if (!visitor)
1213    return;
1214
1215  llvm::FoldingSetNodeID ID;
1216  visitor->Profile(ID);
1217  void *InsertPos;
1218
1219  if (CallbacksSet.FindNodeOrInsertPos(ID, InsertPos)) {
1220    delete visitor;
1221    return;
1222  }
1223
1224  CallbacksSet.InsertNode(visitor, InsertPos);
1225  Callbacks = F.add(visitor, Callbacks);
1226}
1227
1228BugReport::~BugReport() {
1229  for (visitor_iterator I = visitor_begin(), E = visitor_end(); I != E; ++I) {
1230    delete *I;
1231  }
1232}
1233
1234void BugReport::Profile(llvm::FoldingSetNodeID& hash) const {
1235  hash.AddPointer(&BT);
1236  hash.AddInteger(getLocation().getRawEncoding());
1237  hash.AddString(Description);
1238
1239  for (SmallVectorImpl<SourceRange>::const_iterator I =
1240      Ranges.begin(), E = Ranges.end(); I != E; ++I) {
1241    const SourceRange range = *I;
1242    if (!range.isValid())
1243      continue;
1244    hash.AddInteger(range.getBegin().getRawEncoding());
1245    hash.AddInteger(range.getEnd().getRawEncoding());
1246  }
1247}
1248
1249const Stmt *BugReport::getStmt() const {
1250  if (!ErrorNode)
1251    return 0;
1252
1253  ProgramPoint ProgP = ErrorNode->getLocation();
1254  const Stmt *S = NULL;
1255
1256  if (BlockEntrance *BE = dyn_cast<BlockEntrance>(&ProgP)) {
1257    CFGBlock &Exit = ProgP.getLocationContext()->getCFG()->getExit();
1258    if (BE->getBlock() == &Exit)
1259      S = GetPreviousStmt(ErrorNode);
1260  }
1261  if (!S)
1262    S = GetStmt(ProgP);
1263
1264  return S;
1265}
1266
1267std::pair<BugReport::ranges_iterator, BugReport::ranges_iterator>
1268BugReport::getRanges() {
1269    // If no custom ranges, add the range of the statement corresponding to
1270    // the error node.
1271    if (Ranges.empty()) {
1272      if (const Expr *E = dyn_cast_or_null<Expr>(getStmt()))
1273        addRange(E->getSourceRange());
1274      else
1275        return std::make_pair(ranges_iterator(), ranges_iterator());
1276    }
1277
1278    // User-specified absence of range info.
1279    if (Ranges.size() == 1 && !Ranges.begin()->isValid())
1280      return std::make_pair(ranges_iterator(), ranges_iterator());
1281
1282    return std::make_pair(Ranges.begin(), Ranges.end());
1283}
1284
1285SourceLocation BugReport::getLocation() const {
1286  if (ErrorNode) {
1287    (Location.isInvalid() &&
1288     "Either Location or ErrorNode should be specified but not both.");
1289
1290    if (const Stmt *S = GetCurrentOrPreviousStmt(ErrorNode)) {
1291      // For member expressions, return the location of the '.' or '->'.
1292      if (const MemberExpr *ME = dyn_cast<MemberExpr>(S))
1293        return ME->getMemberLoc();
1294      // For binary operators, return the location of the operator.
1295      if (const BinaryOperator *B = dyn_cast<BinaryOperator>(S))
1296        return B->getOperatorLoc();
1297
1298      return S->getLocStart();
1299    }
1300
1301  } else {
1302    assert(Location.isValid());
1303    return Location;
1304  }
1305
1306  return FullSourceLoc();
1307}
1308
1309//===----------------------------------------------------------------------===//
1310// Methods for BugReporter and subclasses.
1311//===----------------------------------------------------------------------===//
1312
1313BugReportEquivClass::~BugReportEquivClass() {
1314  for (iterator I=begin(), E=end(); I!=E; ++I) delete *I;
1315}
1316
1317GRBugReporter::~GRBugReporter() { }
1318BugReporterData::~BugReporterData() {}
1319
1320ExplodedGraph &GRBugReporter::getGraph() { return Eng.getGraph(); }
1321
1322ProgramStateManager&
1323GRBugReporter::getStateManager() { return Eng.getStateManager(); }
1324
1325BugReporter::~BugReporter() {
1326  FlushReports();
1327
1328  // Free the bug reports we are tracking.
1329  typedef std::vector<BugReportEquivClass *> ContTy;
1330  for (ContTy::iterator I = EQClassesVector.begin(), E = EQClassesVector.end();
1331       I != E; ++I) {
1332    delete *I;
1333  }
1334}
1335
1336void BugReporter::FlushReports() {
1337  if (BugTypes.isEmpty())
1338    return;
1339
1340  // First flush the warnings for each BugType.  This may end up creating new
1341  // warnings and new BugTypes.
1342  // FIXME: Only NSErrorChecker needs BugType's FlushReports.
1343  // Turn NSErrorChecker into a proper checker and remove this.
1344  SmallVector<const BugType*, 16> bugTypes;
1345  for (BugTypesTy::iterator I=BugTypes.begin(), E=BugTypes.end(); I!=E; ++I)
1346    bugTypes.push_back(*I);
1347  for (SmallVector<const BugType*, 16>::iterator
1348         I = bugTypes.begin(), E = bugTypes.end(); I != E; ++I)
1349    const_cast<BugType*>(*I)->FlushReports(*this);
1350
1351  typedef llvm::FoldingSet<BugReportEquivClass> SetTy;
1352  for (SetTy::iterator EI=EQClasses.begin(), EE=EQClasses.end(); EI!=EE;++EI){
1353    BugReportEquivClass& EQ = *EI;
1354    FlushReport(EQ);
1355  }
1356
1357  // BugReporter owns and deletes only BugTypes created implicitly through
1358  // EmitBasicReport.
1359  // FIXME: There are leaks from checkers that assume that the BugTypes they
1360  // create will be destroyed by the BugReporter.
1361  for (llvm::StringMap<BugType*>::iterator
1362         I = StrBugTypes.begin(), E = StrBugTypes.end(); I != E; ++I)
1363    delete I->second;
1364
1365  // Remove all references to the BugType objects.
1366  BugTypes = F.getEmptySet();
1367}
1368
1369//===----------------------------------------------------------------------===//
1370// PathDiagnostics generation.
1371//===----------------------------------------------------------------------===//
1372
1373static std::pair<std::pair<ExplodedGraph*, NodeBackMap*>,
1374                 std::pair<ExplodedNode*, unsigned> >
1375MakeReportGraph(const ExplodedGraph* G,
1376                SmallVectorImpl<const ExplodedNode*> &nodes) {
1377
1378  // Create the trimmed graph.  It will contain the shortest paths from the
1379  // error nodes to the root.  In the new graph we should only have one
1380  // error node unless there are two or more error nodes with the same minimum
1381  // path length.
1382  ExplodedGraph* GTrim;
1383  InterExplodedGraphMap* NMap;
1384
1385  llvm::DenseMap<const void*, const void*> InverseMap;
1386  llvm::tie(GTrim, NMap) = G->Trim(nodes.data(), nodes.data() + nodes.size(),
1387                                   &InverseMap);
1388
1389  // Create owning pointers for GTrim and NMap just to ensure that they are
1390  // released when this function exists.
1391  llvm::OwningPtr<ExplodedGraph> AutoReleaseGTrim(GTrim);
1392  llvm::OwningPtr<InterExplodedGraphMap> AutoReleaseNMap(NMap);
1393
1394  // Find the (first) error node in the trimmed graph.  We just need to consult
1395  // the node map (NMap) which maps from nodes in the original graph to nodes
1396  // in the new graph.
1397
1398  std::queue<const ExplodedNode*> WS;
1399  typedef llvm::DenseMap<const ExplodedNode*, unsigned> IndexMapTy;
1400  IndexMapTy IndexMap;
1401
1402  for (unsigned nodeIndex = 0 ; nodeIndex < nodes.size(); ++nodeIndex) {
1403    const ExplodedNode *originalNode = nodes[nodeIndex];
1404    if (const ExplodedNode *N = NMap->getMappedNode(originalNode)) {
1405      WS.push(N);
1406      IndexMap[originalNode] = nodeIndex;
1407    }
1408  }
1409
1410  assert(!WS.empty() && "No error node found in the trimmed graph.");
1411
1412  // Create a new (third!) graph with a single path.  This is the graph
1413  // that will be returned to the caller.
1414  ExplodedGraph *GNew = new ExplodedGraph();
1415
1416  // Sometimes the trimmed graph can contain a cycle.  Perform a reverse BFS
1417  // to the root node, and then construct a new graph that contains only
1418  // a single path.
1419  llvm::DenseMap<const void*,unsigned> Visited;
1420
1421  unsigned cnt = 0;
1422  const ExplodedNode *Root = 0;
1423
1424  while (!WS.empty()) {
1425    const ExplodedNode *Node = WS.front();
1426    WS.pop();
1427
1428    if (Visited.find(Node) != Visited.end())
1429      continue;
1430
1431    Visited[Node] = cnt++;
1432
1433    if (Node->pred_empty()) {
1434      Root = Node;
1435      break;
1436    }
1437
1438    for (ExplodedNode::const_pred_iterator I=Node->pred_begin(),
1439         E=Node->pred_end(); I!=E; ++I)
1440      WS.push(*I);
1441  }
1442
1443  assert(Root);
1444
1445  // Now walk from the root down the BFS path, always taking the successor
1446  // with the lowest number.
1447  ExplodedNode *Last = 0, *First = 0;
1448  NodeBackMap *BM = new NodeBackMap();
1449  unsigned NodeIndex = 0;
1450
1451  for ( const ExplodedNode *N = Root ;;) {
1452    // Lookup the number associated with the current node.
1453    llvm::DenseMap<const void*,unsigned>::iterator I = Visited.find(N);
1454    assert(I != Visited.end());
1455
1456    // Create the equivalent node in the new graph with the same state
1457    // and location.
1458    ExplodedNode *NewN = GNew->getNode(N->getLocation(), N->getState());
1459
1460    // Store the mapping to the original node.
1461    llvm::DenseMap<const void*, const void*>::iterator IMitr=InverseMap.find(N);
1462    assert(IMitr != InverseMap.end() && "No mapping to original node.");
1463    (*BM)[NewN] = (const ExplodedNode*) IMitr->second;
1464
1465    // Link up the new node with the previous node.
1466    if (Last)
1467      NewN->addPredecessor(Last, *GNew);
1468
1469    Last = NewN;
1470
1471    // Are we at the final node?
1472    IndexMapTy::iterator IMI =
1473      IndexMap.find((const ExplodedNode*)(IMitr->second));
1474    if (IMI != IndexMap.end()) {
1475      First = NewN;
1476      NodeIndex = IMI->second;
1477      break;
1478    }
1479
1480    // Find the next successor node.  We choose the node that is marked
1481    // with the lowest DFS number.
1482    ExplodedNode::const_succ_iterator SI = N->succ_begin();
1483    ExplodedNode::const_succ_iterator SE = N->succ_end();
1484    N = 0;
1485
1486    for (unsigned MinVal = 0; SI != SE; ++SI) {
1487
1488      I = Visited.find(*SI);
1489
1490      if (I == Visited.end())
1491        continue;
1492
1493      if (!N || I->second < MinVal) {
1494        N = *SI;
1495        MinVal = I->second;
1496      }
1497    }
1498
1499    assert(N);
1500  }
1501
1502  assert(First);
1503
1504  return std::make_pair(std::make_pair(GNew, BM),
1505                        std::make_pair(First, NodeIndex));
1506}
1507
1508/// CompactPathDiagnostic - This function postprocesses a PathDiagnostic object
1509///  and collapses PathDiagosticPieces that are expanded by macros.
1510static void CompactPathDiagnostic(PathDiagnostic &PD, const SourceManager& SM) {
1511  typedef std::vector<std::pair<PathDiagnosticMacroPiece*, SourceLocation> >
1512          MacroStackTy;
1513
1514  typedef std::vector<PathDiagnosticPiece*>
1515          PiecesTy;
1516
1517  MacroStackTy MacroStack;
1518  PiecesTy Pieces;
1519
1520  for (PathDiagnostic::iterator I = PD.begin(), E = PD.end(); I!=E; ++I) {
1521    // Get the location of the PathDiagnosticPiece.
1522    const FullSourceLoc Loc = I->getLocation().asLocation();
1523
1524    // Determine the instantiation location, which is the location we group
1525    // related PathDiagnosticPieces.
1526    SourceLocation InstantiationLoc = Loc.isMacroID() ?
1527                                      SM.getExpansionLoc(Loc) :
1528                                      SourceLocation();
1529
1530    if (Loc.isFileID()) {
1531      MacroStack.clear();
1532      Pieces.push_back(&*I);
1533      continue;
1534    }
1535
1536    assert(Loc.isMacroID());
1537
1538    // Is the PathDiagnosticPiece within the same macro group?
1539    if (!MacroStack.empty() && InstantiationLoc == MacroStack.back().second) {
1540      MacroStack.back().first->push_back(&*I);
1541      continue;
1542    }
1543
1544    // We aren't in the same group.  Are we descending into a new macro
1545    // or are part of an old one?
1546    PathDiagnosticMacroPiece *MacroGroup = 0;
1547
1548    SourceLocation ParentInstantiationLoc = InstantiationLoc.isMacroID() ?
1549                                          SM.getExpansionLoc(Loc) :
1550                                          SourceLocation();
1551
1552    // Walk the entire macro stack.
1553    while (!MacroStack.empty()) {
1554      if (InstantiationLoc == MacroStack.back().second) {
1555        MacroGroup = MacroStack.back().first;
1556        break;
1557      }
1558
1559      if (ParentInstantiationLoc == MacroStack.back().second) {
1560        MacroGroup = MacroStack.back().first;
1561        break;
1562      }
1563
1564      MacroStack.pop_back();
1565    }
1566
1567    if (!MacroGroup || ParentInstantiationLoc == MacroStack.back().second) {
1568      // Create a new macro group and add it to the stack.
1569      PathDiagnosticMacroPiece *NewGroup = new PathDiagnosticMacroPiece(Loc);
1570
1571      if (MacroGroup)
1572        MacroGroup->push_back(NewGroup);
1573      else {
1574        assert(InstantiationLoc.isFileID());
1575        Pieces.push_back(NewGroup);
1576      }
1577
1578      MacroGroup = NewGroup;
1579      MacroStack.push_back(std::make_pair(MacroGroup, InstantiationLoc));
1580    }
1581
1582    // Finally, add the PathDiagnosticPiece to the group.
1583    MacroGroup->push_back(&*I);
1584  }
1585
1586  // Now take the pieces and construct a new PathDiagnostic.
1587  PD.resetPath(false);
1588
1589  for (PiecesTy::iterator I=Pieces.begin(), E=Pieces.end(); I!=E; ++I) {
1590    if (PathDiagnosticMacroPiece *MP=dyn_cast<PathDiagnosticMacroPiece>(*I))
1591      if (!MP->containsEvent()) {
1592        delete MP;
1593        continue;
1594      }
1595
1596    PD.push_back(*I);
1597  }
1598}
1599
1600void GRBugReporter::GeneratePathDiagnostic(PathDiagnostic& PD,
1601                        SmallVectorImpl<BugReport *> &bugReports) {
1602
1603  assert(!bugReports.empty());
1604  SmallVector<const ExplodedNode *, 10> errorNodes;
1605  for (SmallVectorImpl<BugReport*>::iterator I = bugReports.begin(),
1606    E = bugReports.end(); I != E; ++I) {
1607      errorNodes.push_back((*I)->getErrorNode());
1608  }
1609
1610  // Construct a new graph that contains only a single path from the error
1611  // node to a root.
1612  const std::pair<std::pair<ExplodedGraph*, NodeBackMap*>,
1613  std::pair<ExplodedNode*, unsigned> >&
1614    GPair = MakeReportGraph(&getGraph(), errorNodes);
1615
1616  // Find the BugReport with the original location.
1617  assert(GPair.second.second < bugReports.size());
1618  BugReport *R = bugReports[GPair.second.second];
1619  assert(R && "No original report found for sliced graph.");
1620
1621  llvm::OwningPtr<ExplodedGraph> ReportGraph(GPair.first.first);
1622  llvm::OwningPtr<NodeBackMap> BackMap(GPair.first.second);
1623  const ExplodedNode *N = GPair.second.first;
1624
1625  // Start building the path diagnostic...
1626  PathDiagnosticBuilder PDB(*this, R, BackMap.get(), getPathDiagnosticClient());
1627
1628  // Register additional node visitors.
1629  R->addVisitor(new NilReceiverBRVisitor());
1630  R->addVisitor(new ConditionBRVisitor());
1631
1632  // Generate the very last diagnostic piece - the piece is visible before
1633  // the trace is expanded.
1634  PathDiagnosticPiece *LastPiece = 0;
1635  for (BugReport::visitor_iterator I = R->visitor_begin(),
1636                                   E = R->visitor_end(); I!=E; ++I) {
1637    if (PathDiagnosticPiece *Piece = (*I)->getEndPath(PDB, N, *R)) {
1638      assert (!LastPiece &&
1639              "There can only be one final piece in a diagnostic.");
1640      LastPiece = Piece;
1641    }
1642  }
1643  if (!LastPiece)
1644    LastPiece = BugReporterVisitor::getDefaultEndPath(PDB, N, *R);
1645  if (LastPiece)
1646    PD.push_back(LastPiece);
1647  else
1648    return;
1649
1650  switch (PDB.getGenerationScheme()) {
1651    case PathDiagnosticClient::Extensive:
1652      GenerateExtensivePathDiagnostic(PD, PDB, N);
1653      break;
1654    case PathDiagnosticClient::Minimal:
1655      GenerateMinimalPathDiagnostic(PD, PDB, N);
1656      break;
1657  }
1658}
1659
1660void BugReporter::Register(BugType *BT) {
1661  BugTypes = F.add(BugTypes, BT);
1662}
1663
1664void BugReporter::EmitReport(BugReport* R) {
1665  // Compute the bug report's hash to determine its equivalence class.
1666  llvm::FoldingSetNodeID ID;
1667  R->Profile(ID);
1668
1669  // Lookup the equivance class.  If there isn't one, create it.
1670  BugType& BT = R->getBugType();
1671  Register(&BT);
1672  void *InsertPos;
1673  BugReportEquivClass* EQ = EQClasses.FindNodeOrInsertPos(ID, InsertPos);
1674
1675  if (!EQ) {
1676    EQ = new BugReportEquivClass(R);
1677    EQClasses.InsertNode(EQ, InsertPos);
1678    EQClassesVector.push_back(EQ);
1679  }
1680  else
1681    EQ->AddReport(R);
1682}
1683
1684
1685//===----------------------------------------------------------------------===//
1686// Emitting reports in equivalence classes.
1687//===----------------------------------------------------------------------===//
1688
1689namespace {
1690struct FRIEC_WLItem {
1691  const ExplodedNode *N;
1692  ExplodedNode::const_succ_iterator I, E;
1693
1694  FRIEC_WLItem(const ExplodedNode *n)
1695  : N(n), I(N->succ_begin()), E(N->succ_end()) {}
1696};
1697}
1698
1699static BugReport *
1700FindReportInEquivalenceClass(BugReportEquivClass& EQ,
1701                             SmallVectorImpl<BugReport*> &bugReports) {
1702
1703  BugReportEquivClass::iterator I = EQ.begin(), E = EQ.end();
1704  assert(I != E);
1705  BugReport *R = *I;
1706  BugType& BT = R->getBugType();
1707
1708  // If we don't need to suppress any of the nodes because they are
1709  // post-dominated by a sink, simply add all the nodes in the equivalence class
1710  // to 'Nodes'.  Any of the reports will serve as a "representative" report.
1711  if (!BT.isSuppressOnSink()) {
1712    for (BugReportEquivClass::iterator I=EQ.begin(), E=EQ.end(); I!=E; ++I) {
1713      const ExplodedNode *N = I->getErrorNode();
1714      if (N) {
1715        R = *I;
1716        bugReports.push_back(R);
1717      }
1718    }
1719    return R;
1720  }
1721
1722  // For bug reports that should be suppressed when all paths are post-dominated
1723  // by a sink node, iterate through the reports in the equivalence class
1724  // until we find one that isn't post-dominated (if one exists).  We use a
1725  // DFS traversal of the ExplodedGraph to find a non-sink node.  We could write
1726  // this as a recursive function, but we don't want to risk blowing out the
1727  // stack for very long paths.
1728  BugReport *exampleReport = 0;
1729
1730  for (; I != E; ++I) {
1731    R = *I;
1732    const ExplodedNode *errorNode = R->getErrorNode();
1733
1734    if (!errorNode)
1735      continue;
1736    if (errorNode->isSink()) {
1737      assert(false &&
1738           "BugType::isSuppressSink() should not be 'true' for sink end nodes");
1739      return 0;
1740    }
1741    // No successors?  By definition this nodes isn't post-dominated by a sink.
1742    if (errorNode->succ_empty()) {
1743      bugReports.push_back(R);
1744      if (!exampleReport)
1745        exampleReport = R;
1746      continue;
1747    }
1748
1749    // At this point we know that 'N' is not a sink and it has at least one
1750    // successor.  Use a DFS worklist to find a non-sink end-of-path node.
1751    typedef FRIEC_WLItem WLItem;
1752    typedef SmallVector<WLItem, 10> DFSWorkList;
1753    llvm::DenseMap<const ExplodedNode *, unsigned> Visited;
1754
1755    DFSWorkList WL;
1756    WL.push_back(errorNode);
1757    Visited[errorNode] = 1;
1758
1759    while (!WL.empty()) {
1760      WLItem &WI = WL.back();
1761      assert(!WI.N->succ_empty());
1762
1763      for (; WI.I != WI.E; ++WI.I) {
1764        const ExplodedNode *Succ = *WI.I;
1765        // End-of-path node?
1766        if (Succ->succ_empty()) {
1767          // If we found an end-of-path node that is not a sink.
1768          if (!Succ->isSink()) {
1769            bugReports.push_back(R);
1770            if (!exampleReport)
1771              exampleReport = R;
1772            WL.clear();
1773            break;
1774          }
1775          // Found a sink?  Continue on to the next successor.
1776          continue;
1777        }
1778        // Mark the successor as visited.  If it hasn't been explored,
1779        // enqueue it to the DFS worklist.
1780        unsigned &mark = Visited[Succ];
1781        if (!mark) {
1782          mark = 1;
1783          WL.push_back(Succ);
1784          break;
1785        }
1786      }
1787
1788      // The worklist may have been cleared at this point.  First
1789      // check if it is empty before checking the last item.
1790      if (!WL.empty() && &WL.back() == &WI)
1791        WL.pop_back();
1792    }
1793  }
1794
1795  // ExampleReport will be NULL if all the nodes in the equivalence class
1796  // were post-dominated by sinks.
1797  return exampleReport;
1798}
1799
1800//===----------------------------------------------------------------------===//
1801// DiagnosticCache.  This is a hack to cache analyzer diagnostics.  It
1802// uses global state, which eventually should go elsewhere.
1803//===----------------------------------------------------------------------===//
1804namespace {
1805class DiagCacheItem : public llvm::FoldingSetNode {
1806  llvm::FoldingSetNodeID ID;
1807public:
1808  DiagCacheItem(BugReport *R, PathDiagnostic *PD) {
1809    ID.AddString(R->getBugType().getName());
1810    ID.AddString(R->getBugType().getCategory());
1811    ID.AddString(R->getDescription());
1812    ID.AddInteger(R->getLocation().getRawEncoding());
1813    PD->Profile(ID);
1814  }
1815
1816  void Profile(llvm::FoldingSetNodeID &id) {
1817    id = ID;
1818  }
1819
1820  llvm::FoldingSetNodeID &getID() { return ID; }
1821};
1822}
1823
1824static bool IsCachedDiagnostic(BugReport *R, PathDiagnostic *PD) {
1825  // FIXME: Eventually this diagnostic cache should reside in something
1826  // like AnalysisManager instead of being a static variable.  This is
1827  // really unsafe in the long term.
1828  typedef llvm::FoldingSet<DiagCacheItem> DiagnosticCache;
1829  static DiagnosticCache DC;
1830
1831  void *InsertPos;
1832  DiagCacheItem *Item = new DiagCacheItem(R, PD);
1833
1834  if (DC.FindNodeOrInsertPos(Item->getID(), InsertPos)) {
1835    delete Item;
1836    return true;
1837  }
1838
1839  DC.InsertNode(Item, InsertPos);
1840  return false;
1841}
1842
1843void BugReporter::FlushReport(BugReportEquivClass& EQ) {
1844  SmallVector<BugReport*, 10> bugReports;
1845  BugReport *exampleReport = FindReportInEquivalenceClass(EQ, bugReports);
1846  if (!exampleReport)
1847    return;
1848
1849  PathDiagnosticClient* PD = getPathDiagnosticClient();
1850
1851  // FIXME: Make sure we use the 'R' for the path that was actually used.
1852  // Probably doesn't make a difference in practice.
1853  BugType& BT = exampleReport->getBugType();
1854
1855  llvm::OwningPtr<PathDiagnostic>
1856    D(new PathDiagnostic(exampleReport->getBugType().getName(),
1857                         !PD || PD->useVerboseDescription()
1858                         ? exampleReport->getDescription()
1859                         : exampleReport->getShortDescription(),
1860                         BT.getCategory()));
1861
1862  if (!bugReports.empty())
1863    GeneratePathDiagnostic(*D.get(), bugReports);
1864
1865  if (IsCachedDiagnostic(exampleReport, D.get()))
1866    return;
1867
1868  // Get the meta data.
1869  const BugReport::ExtraTextList &Meta =
1870                                  exampleReport->getExtraText();
1871  for (BugReport::ExtraTextList::const_iterator i = Meta.begin(),
1872                                                e = Meta.end(); i != e; ++i) {
1873    D->addMeta(*i);
1874  }
1875
1876  // Emit a summary diagnostic to the regular Diagnostics engine.
1877  BugReport::ranges_iterator Beg, End;
1878  llvm::tie(Beg, End) = exampleReport->getRanges();
1879  Diagnostic &Diag = getDiagnostic();
1880  FullSourceLoc L(exampleReport->getLocation(), getSourceManager());
1881
1882  // Search the description for '%', as that will be interpretted as a
1883  // format character by FormatDiagnostics.
1884  StringRef desc = exampleReport->getShortDescription();
1885  unsigned ErrorDiag;
1886  {
1887    llvm::SmallString<512> TmpStr;
1888    llvm::raw_svector_ostream Out(TmpStr);
1889    for (StringRef::iterator I=desc.begin(), E=desc.end(); I!=E; ++I)
1890      if (*I == '%')
1891        Out << "%%";
1892      else
1893        Out << *I;
1894
1895    Out.flush();
1896    ErrorDiag = Diag.getCustomDiagID(Diagnostic::Warning, TmpStr);
1897  }
1898
1899  {
1900    DiagnosticBuilder diagBuilder = Diag.Report(L, ErrorDiag);
1901    for (BugReport::ranges_iterator I = Beg; I != End; ++I)
1902      diagBuilder << *I;
1903  }
1904
1905  // Emit a full diagnostic for the path if we have a PathDiagnosticClient.
1906  if (!PD)
1907    return;
1908
1909  if (D->empty()) {
1910    PathDiagnosticPiece *piece =
1911      new PathDiagnosticEventPiece(L, exampleReport->getDescription());
1912
1913    for ( ; Beg != End; ++Beg) piece->addRange(*Beg);
1914    D->push_back(piece);
1915  }
1916
1917  PD->HandlePathDiagnostic(D.take());
1918}
1919
1920void BugReporter::EmitBasicReport(StringRef name, StringRef str,
1921                                  SourceLocation Loc,
1922                                  SourceRange* RBeg, unsigned NumRanges) {
1923  EmitBasicReport(name, "", str, Loc, RBeg, NumRanges);
1924}
1925
1926void BugReporter::EmitBasicReport(StringRef name,
1927                                  StringRef category,
1928                                  StringRef str, SourceLocation Loc,
1929                                  SourceRange* RBeg, unsigned NumRanges) {
1930
1931  // 'BT' is owned by BugReporter.
1932  BugType *BT = getBugTypeForName(name, category);
1933  FullSourceLoc L = getContext().getFullLoc(Loc);
1934  BugReport *R = new BugReport(*BT, str, L);
1935  for ( ; NumRanges > 0 ; --NumRanges, ++RBeg) R->addRange(*RBeg);
1936  EmitReport(R);
1937}
1938
1939BugType *BugReporter::getBugTypeForName(StringRef name,
1940                                        StringRef category) {
1941  llvm::SmallString<136> fullDesc;
1942  llvm::raw_svector_ostream(fullDesc) << name << ":" << category;
1943  llvm::StringMapEntry<BugType *> &
1944      entry = StrBugTypes.GetOrCreateValue(fullDesc);
1945  BugType *BT = entry.getValue();
1946  if (!BT) {
1947    BT = new BugType(name, category);
1948    entry.setValue(BT);
1949  }
1950  return BT;
1951}
1952