BugReporterVisitors.cpp revision 685379965c1b105ce89cf4f6c60810932b7f4d0d 
1// BugReporterVisitors.cpp - Helpers for reporting 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 a set of BugReporter "visitors" which can be used to
11//  enhance the diagnostics reported for a bug.
12//
13//===----------------------------------------------------------------------===//
14#include "clang/StaticAnalyzer/Core/BugReporter/BugReporterVisitor.h"
15
16#include "clang/AST/Expr.h"
17#include "clang/AST/ExprObjC.h"
18#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
19#include "clang/StaticAnalyzer/Core/BugReporter/PathDiagnostic.h"
20#include "clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h"
21#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
22#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
23#include "llvm/ADT/SmallString.h"
24
25using namespace clang;
26using namespace ento;
27
28//===----------------------------------------------------------------------===//
29// Utility functions.
30//===----------------------------------------------------------------------===//
31
32const Stmt *bugreporter::GetDerefExpr(const ExplodedNode *N) {
33  // Pattern match for a few useful cases (do something smarter later):
34  //   a[0], p->f, *p
35  const Stmt *S = N->getLocationAs<PostStmt>()->getStmt();
36
37  while (true) {
38    if (const BinaryOperator *B = dyn_cast<BinaryOperator>(S)) {
39      assert(B->isAssignmentOp());
40      S = B->getLHS()->IgnoreParenCasts();
41      continue;
42    }
43    else if (const UnaryOperator *U = dyn_cast<UnaryOperator>(S)) {
44      if (U->getOpcode() == UO_Deref)
45        return U->getSubExpr()->IgnoreParenCasts();
46    }
47    else if (const MemberExpr *ME = dyn_cast<MemberExpr>(S)) {
48      return ME->getBase()->IgnoreParenCasts();
49    }
50    else if (const ArraySubscriptExpr *AE = dyn_cast<ArraySubscriptExpr>(S)) {
51      return AE->getBase();
52    }
53    break;
54  }
55
56  return NULL;
57}
58
59const Stmt *bugreporter::GetDenomExpr(const ExplodedNode *N) {
60  const Stmt *S = N->getLocationAs<PreStmt>()->getStmt();
61  if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(S))
62    return BE->getRHS();
63  return NULL;
64}
65
66const Stmt *bugreporter::GetRetValExpr(const ExplodedNode *N) {
67  const Stmt *S = N->getLocationAs<PostStmt>()->getStmt();
68  if (const ReturnStmt *RS = dyn_cast<ReturnStmt>(S))
69    return RS->getRetValue();
70  return NULL;
71}
72
73//===----------------------------------------------------------------------===//
74// Definitions for bug reporter visitors.
75//===----------------------------------------------------------------------===//
76
77PathDiagnosticPiece*
78BugReporterVisitor::getEndPath(BugReporterContext &BRC,
79                               const ExplodedNode *EndPathNode,
80                               BugReport &BR) {
81  return 0;
82}
83
84PathDiagnosticPiece*
85BugReporterVisitor::getDefaultEndPath(BugReporterContext &BRC,
86                                      const ExplodedNode *EndPathNode,
87                                      BugReport &BR) {
88  PathDiagnosticLocation L =
89    PathDiagnosticLocation::createEndOfPath(EndPathNode,BRC.getSourceManager());
90
91  BugReport::ranges_iterator Beg, End;
92  llvm::tie(Beg, End) = BR.getRanges();
93
94  // Only add the statement itself as a range if we didn't specify any
95  // special ranges for this report.
96  PathDiagnosticPiece *P = new PathDiagnosticEventPiece(L,
97      BR.getDescription(),
98      Beg == End);
99  for (; Beg != End; ++Beg)
100    P->addRange(*Beg);
101
102  return P;
103}
104
105
106void FindLastStoreBRVisitor ::Profile(llvm::FoldingSetNodeID &ID) const {
107  static int tag = 0;
108  ID.AddPointer(&tag);
109  ID.AddPointer(R);
110  ID.Add(V);
111}
112
113PathDiagnosticPiece *FindLastStoreBRVisitor::VisitNode(const ExplodedNode *N,
114                                                     const ExplodedNode *PrevN,
115                                                     BugReporterContext &BRC,
116                                                     BugReport &BR) {
117
118  if (satisfied)
119    return NULL;
120
121  if (!StoreSite) {
122    // Make sure the region is actually bound to value V here.
123    // This is necessary because the region may not actually be live at the
124    // report's error node.
125    if (N->getState()->getSVal(R) != V)
126      return NULL;
127
128    const ExplodedNode *Node = N, *Last = N;
129
130    // Now look for the store of V.
131    for ( ; Node ; Node = Node->getFirstPred()) {
132      if (const VarRegion *VR = dyn_cast<VarRegion>(R)) {
133        if (const PostStmt *P = Node->getLocationAs<PostStmt>())
134          if (const DeclStmt *DS = P->getStmtAs<DeclStmt>())
135            if (DS->getSingleDecl() == VR->getDecl()) {
136              // Record the last seen initialization point.
137              Last = Node;
138              break;
139            }
140      }
141
142      // Does the region still bind to value V?  If not, we are done
143      // looking for store sites.
144      if (Node->getState()->getSVal(R) != V)
145        break;
146
147      Last = Node;
148    }
149
150    if (!Node) {
151      satisfied = true;
152      return NULL;
153    }
154
155    StoreSite = Last;
156  }
157
158  if (StoreSite != N)
159    return NULL;
160
161  satisfied = true;
162  SmallString<256> sbuf;
163  llvm::raw_svector_ostream os(sbuf);
164
165  if (const PostStmt *PS = N->getLocationAs<PostStmt>()) {
166    if (const DeclStmt *DS = PS->getStmtAs<DeclStmt>()) {
167
168      if (const VarRegion *VR = dyn_cast<VarRegion>(R)) {
169        os << "Variable '" << *VR->getDecl() << "' ";
170      }
171      else
172        return NULL;
173
174      if (isa<loc::ConcreteInt>(V)) {
175        bool b = false;
176        if (R->isBoundable()) {
177          if (const TypedValueRegion *TR = dyn_cast<TypedValueRegion>(R)) {
178            if (TR->getValueType()->isObjCObjectPointerType()) {
179              os << "initialized to nil";
180              b = true;
181            }
182          }
183        }
184
185        if (!b)
186          os << "initialized to a null pointer value";
187      }
188      else if (isa<nonloc::ConcreteInt>(V)) {
189        os << "initialized to " << cast<nonloc::ConcreteInt>(V).getValue();
190      }
191      else if (V.isUndef()) {
192        if (isa<VarRegion>(R)) {
193          const VarDecl *VD = cast<VarDecl>(DS->getSingleDecl());
194          if (VD->getInit())
195            os << "initialized to a garbage value";
196          else
197            os << "declared without an initial value";
198        }
199      }
200      else {
201        os << "initialized here";
202      }
203    }
204  }
205
206  if (os.str().empty()) {
207    if (isa<loc::ConcreteInt>(V)) {
208      bool b = false;
209      if (R->isBoundable()) {
210        if (const TypedValueRegion *TR = dyn_cast<TypedValueRegion>(R)) {
211          if (TR->getValueType()->isObjCObjectPointerType()) {
212            os << "nil object reference stored to ";
213            b = true;
214          }
215        }
216      }
217
218      if (!b)
219        os << "Null pointer value stored to ";
220    }
221    else if (V.isUndef()) {
222      os << "Uninitialized value stored to ";
223    }
224    else if (isa<nonloc::ConcreteInt>(V)) {
225      os << "The value " << cast<nonloc::ConcreteInt>(V).getValue()
226               << " is assigned to ";
227    }
228    else
229      os << "Value assigned to ";
230
231    if (const VarRegion *VR = dyn_cast<VarRegion>(R)) {
232      os << '\'' << *VR->getDecl() << '\'';
233    }
234    else
235      return NULL;
236  }
237
238  // Construct a new PathDiagnosticPiece.
239  ProgramPoint P = N->getLocation();
240  PathDiagnosticLocation L =
241    PathDiagnosticLocation::create(P, BRC.getSourceManager());
242  if (!L.isValid())
243    return NULL;
244  return new PathDiagnosticEventPiece(L, os.str());
245}
246
247void TrackConstraintBRVisitor::Profile(llvm::FoldingSetNodeID &ID) const {
248  static int tag = 0;
249  ID.AddPointer(&tag);
250  ID.AddBoolean(Assumption);
251  ID.Add(Constraint);
252}
253
254PathDiagnosticPiece *
255TrackConstraintBRVisitor::VisitNode(const ExplodedNode *N,
256                                    const ExplodedNode *PrevN,
257                                    BugReporterContext &BRC,
258                                    BugReport &BR) {
259  if (isSatisfied)
260    return NULL;
261
262  // Check if in the previous state it was feasible for this constraint
263  // to *not* be true.
264  if (PrevN->getState()->assume(Constraint, !Assumption)) {
265
266    isSatisfied = true;
267
268    // As a sanity check, make sure that the negation of the constraint
269    // was infeasible in the current state.  If it is feasible, we somehow
270    // missed the transition point.
271    if (N->getState()->assume(Constraint, !Assumption))
272      return NULL;
273
274    // We found the transition point for the constraint.  We now need to
275    // pretty-print the constraint. (work-in-progress)
276    std::string sbuf;
277    llvm::raw_string_ostream os(sbuf);
278
279    if (isa<Loc>(Constraint)) {
280      os << "Assuming pointer value is ";
281      os << (Assumption ? "non-null" : "null");
282    }
283
284    if (os.str().empty())
285      return NULL;
286
287    // Construct a new PathDiagnosticPiece.
288    ProgramPoint P = N->getLocation();
289    PathDiagnosticLocation L =
290      PathDiagnosticLocation::create(P, BRC.getSourceManager());
291    if (!L.isValid())
292      return NULL;
293    return new PathDiagnosticEventPiece(L, os.str());
294  }
295
296  return NULL;
297}
298
299void bugreporter::addTrackNullOrUndefValueVisitor(const ExplodedNode *N,
300                                                  const Stmt *S,
301                                                  BugReport *report) {
302  if (!S || !N)
303    return;
304
305  ProgramStateManager &StateMgr = N->getState()->getStateManager();
306
307  // Walk through nodes until we get one that matches the statement
308  // exactly.
309  while (N) {
310    const ProgramPoint &pp = N->getLocation();
311    if (const PostStmt *ps = dyn_cast<PostStmt>(&pp)) {
312      if (ps->getStmt() == S)
313        break;
314    }
315    N = N->getFirstPred();
316  }
317
318  if (!N)
319    return;
320
321  ProgramStateRef state = N->getState();
322
323  // Walk through lvalue-to-rvalue conversions.
324  const Expr *Ex = dyn_cast<Expr>(S);
325  if (Ex) {
326    Ex = Ex->IgnoreParenLValueCasts();
327    if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Ex)) {
328      if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
329        const VarRegion *R =
330          StateMgr.getRegionManager().getVarRegion(VD, N->getLocationContext());
331
332        // What did we load?
333        SVal V = state->getRawSVal(loc::MemRegionVal(R));
334        report->markInteresting(R);
335        report->markInteresting(V);
336
337        if (V.getAsLocSymbol()) {
338          BugReporterVisitor *ConstraintTracker
339            = new TrackConstraintBRVisitor(cast<loc::MemRegionVal>(V), false);
340          report->addVisitor(ConstraintTracker);
341        }
342
343        report->addVisitor(new FindLastStoreBRVisitor(V, R));
344        return;
345      }
346    }
347  }
348
349  SVal V = state->getSValAsScalarOrLoc(S, N->getLocationContext());
350
351  // Uncomment this to find cases where we aren't properly getting the
352  // base value that was dereferenced.
353  // assert(!V.isUnknownOrUndef());
354
355  // Is it a symbolic value?
356  if (loc::MemRegionVal *L = dyn_cast<loc::MemRegionVal>(&V)) {
357    const SubRegion *R = cast<SubRegion>(L->getRegion());
358    while (R && !isa<SymbolicRegion>(R)) {
359      R = dyn_cast<SubRegion>(R->getSuperRegion());
360    }
361
362    if (R) {
363      report->markInteresting(R);
364      report->addVisitor(new TrackConstraintBRVisitor(loc::MemRegionVal(R),
365                                                      false));
366    }
367  }
368}
369
370BugReporterVisitor *
371FindLastStoreBRVisitor::createVisitorObject(const ExplodedNode *N,
372                                            const MemRegion *R) {
373  assert(R && "The memory region is null.");
374
375  ProgramStateRef state = N->getState();
376  SVal V = state->getSVal(R);
377  if (V.isUnknown())
378    return 0;
379
380  return new FindLastStoreBRVisitor(V, R);
381}
382
383
384PathDiagnosticPiece *NilReceiverBRVisitor::VisitNode(const ExplodedNode *N,
385                                                     const ExplodedNode *PrevN,
386                                                     BugReporterContext &BRC,
387                                                     BugReport &BR) {
388  const PostStmt *P = N->getLocationAs<PostStmt>();
389  if (!P)
390    return 0;
391  const ObjCMessageExpr *ME = P->getStmtAs<ObjCMessageExpr>();
392  if (!ME)
393    return 0;
394  const Expr *Receiver = ME->getInstanceReceiver();
395  if (!Receiver)
396    return 0;
397  ProgramStateRef state = N->getState();
398  const SVal &V = state->getSVal(Receiver, N->getLocationContext());
399  const DefinedOrUnknownSVal *DV = dyn_cast<DefinedOrUnknownSVal>(&V);
400  if (!DV)
401    return 0;
402  state = state->assume(*DV, true);
403  if (state)
404    return 0;
405
406  // The receiver was nil, and hence the method was skipped.
407  // Register a BugReporterVisitor to issue a message telling us how
408  // the receiver was null.
409  bugreporter::addTrackNullOrUndefValueVisitor(N, Receiver, &BR);
410  // Issue a message saying that the method was skipped.
411  PathDiagnosticLocation L(Receiver, BRC.getSourceManager(),
412                                     N->getLocationContext());
413  return new PathDiagnosticEventPiece(L, "No method is called "
414      "because the receiver is nil");
415}
416
417// Registers every VarDecl inside a Stmt with a last store visitor.
418void FindLastStoreBRVisitor::registerStatementVarDecls(BugReport &BR,
419                                                       const Stmt *S) {
420  const ExplodedNode *N = BR.getErrorNode();
421  std::deque<const Stmt *> WorkList;
422  WorkList.push_back(S);
423
424  while (!WorkList.empty()) {
425    const Stmt *Head = WorkList.front();
426    WorkList.pop_front();
427
428    ProgramStateRef state = N->getState();
429    ProgramStateManager &StateMgr = state->getStateManager();
430
431    if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Head)) {
432      if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
433        const VarRegion *R =
434        StateMgr.getRegionManager().getVarRegion(VD, N->getLocationContext());
435
436        // What did we load?
437        SVal V = state->getSVal(S, N->getLocationContext());
438
439        if (isa<loc::ConcreteInt>(V) || isa<nonloc::ConcreteInt>(V)) {
440          // Register a new visitor with the BugReport.
441          BR.addVisitor(new FindLastStoreBRVisitor(V, R));
442        }
443      }
444    }
445
446    for (Stmt::const_child_iterator I = Head->child_begin();
447        I != Head->child_end(); ++I)
448      WorkList.push_back(*I);
449  }
450}
451
452//===----------------------------------------------------------------------===//
453// Visitor that tries to report interesting diagnostics from conditions.
454//===----------------------------------------------------------------------===//
455PathDiagnosticPiece *ConditionBRVisitor::VisitNode(const ExplodedNode *N,
456                                                   const ExplodedNode *Prev,
457                                                   BugReporterContext &BRC,
458                                                   BugReport &BR) {
459  PathDiagnosticPiece *piece = VisitNodeImpl(N, Prev, BRC, BR);
460  if (PathDiagnosticEventPiece *ev =
461      dyn_cast_or_null<PathDiagnosticEventPiece>(piece))
462    ev->setPrunable(true, /* override */ false);
463  return piece;
464}
465
466PathDiagnosticPiece *ConditionBRVisitor::VisitNodeImpl(const ExplodedNode *N,
467                                                       const ExplodedNode *Prev,
468                                                       BugReporterContext &BRC,
469                                                       BugReport &BR) {
470
471  const ProgramPoint &progPoint = N->getLocation();
472
473  ProgramStateRef CurrentState = N->getState();
474  ProgramStateRef PrevState = Prev->getState();
475
476  // Compare the GDMs of the state, because that is where constraints
477  // are managed.  Note that ensure that we only look at nodes that
478  // were generated by the analyzer engine proper, not checkers.
479  if (CurrentState->getGDM().getRoot() ==
480      PrevState->getGDM().getRoot())
481    return 0;
482
483  // If an assumption was made on a branch, it should be caught
484  // here by looking at the state transition.
485  if (const BlockEdge *BE = dyn_cast<BlockEdge>(&progPoint)) {
486    const CFGBlock *srcBlk = BE->getSrc();
487    if (const Stmt *term = srcBlk->getTerminator())
488      return VisitTerminator(term, N, srcBlk, BE->getDst(), BR, BRC);
489    return 0;
490  }
491
492  if (const PostStmt *PS = dyn_cast<PostStmt>(&progPoint)) {
493    // FIXME: Assuming that BugReporter is a GRBugReporter is a layering
494    // violation.
495    const std::pair<const ProgramPointTag *, const ProgramPointTag *> &tags =
496      cast<GRBugReporter>(BRC.getBugReporter()).
497        getEngine().getEagerlyAssumeTags();
498
499    const ProgramPointTag *tag = PS->getTag();
500    if (tag == tags.first)
501      return VisitTrueTest(cast<Expr>(PS->getStmt()), true,
502                           BRC, BR, N);
503    if (tag == tags.second)
504      return VisitTrueTest(cast<Expr>(PS->getStmt()), false,
505                           BRC, BR, N);
506
507    return 0;
508  }
509
510  return 0;
511}
512
513PathDiagnosticPiece *
514ConditionBRVisitor::VisitTerminator(const Stmt *Term,
515                                    const ExplodedNode *N,
516                                    const CFGBlock *srcBlk,
517                                    const CFGBlock *dstBlk,
518                                    BugReport &R,
519                                    BugReporterContext &BRC) {
520  const Expr *Cond = 0;
521
522  switch (Term->getStmtClass()) {
523  default:
524    return 0;
525  case Stmt::IfStmtClass:
526    Cond = cast<IfStmt>(Term)->getCond();
527    break;
528  case Stmt::ConditionalOperatorClass:
529    Cond = cast<ConditionalOperator>(Term)->getCond();
530    break;
531  }
532
533  assert(Cond);
534  assert(srcBlk->succ_size() == 2);
535  const bool tookTrue = *(srcBlk->succ_begin()) == dstBlk;
536  return VisitTrueTest(Cond->IgnoreParenNoopCasts(BRC.getASTContext()),
537                       tookTrue, BRC, R, N);
538}
539
540PathDiagnosticPiece *
541ConditionBRVisitor::VisitTrueTest(const Expr *Cond,
542                                  bool tookTrue,
543                                  BugReporterContext &BRC,
544                                  BugReport &R,
545                                  const ExplodedNode *N) {
546
547  const Expr *Ex = Cond;
548
549  while (true) {
550    Ex = Ex->IgnoreParens();
551    switch (Ex->getStmtClass()) {
552      default:
553        return 0;
554      case Stmt::BinaryOperatorClass:
555        return VisitTrueTest(Cond, cast<BinaryOperator>(Ex), tookTrue, BRC,
556                             R, N);
557      case Stmt::DeclRefExprClass:
558        return VisitTrueTest(Cond, cast<DeclRefExpr>(Ex), tookTrue, BRC,
559                             R, N);
560      case Stmt::UnaryOperatorClass: {
561        const UnaryOperator *UO = cast<UnaryOperator>(Ex);
562        if (UO->getOpcode() == UO_LNot) {
563          tookTrue = !tookTrue;
564          Ex = UO->getSubExpr()->IgnoreParenNoopCasts(BRC.getASTContext());
565          continue;
566        }
567        return 0;
568      }
569    }
570  }
571}
572
573bool ConditionBRVisitor::patternMatch(const Expr *Ex, llvm::raw_ostream &Out,
574                                      BugReporterContext &BRC,
575                                      BugReport &report,
576                                      const ExplodedNode *N,
577                                      llvm::Optional<bool> &prunable) {
578  const Expr *OriginalExpr = Ex;
579  Ex = Ex->IgnoreParenCasts();
580
581  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Ex)) {
582    const bool quotes = isa<VarDecl>(DR->getDecl());
583    if (quotes) {
584      Out << '\'';
585      const LocationContext *LCtx = N->getLocationContext();
586      const ProgramState *state = N->getState().getPtr();
587      if (const MemRegion *R = state->getLValue(cast<VarDecl>(DR->getDecl()),
588                                                LCtx).getAsRegion()) {
589        if (report.isInteresting(R))
590          prunable = false;
591        else {
592          const ProgramState *state = N->getState().getPtr();
593          SVal V = state->getSVal(R);
594          if (report.isInteresting(V))
595            prunable = false;
596        }
597      }
598    }
599    Out << DR->getDecl()->getDeclName().getAsString();
600    if (quotes)
601      Out << '\'';
602    return quotes;
603  }
604
605  if (const IntegerLiteral *IL = dyn_cast<IntegerLiteral>(Ex)) {
606    QualType OriginalTy = OriginalExpr->getType();
607    if (OriginalTy->isPointerType()) {
608      if (IL->getValue() == 0) {
609        Out << "null";
610        return false;
611      }
612    }
613    else if (OriginalTy->isObjCObjectPointerType()) {
614      if (IL->getValue() == 0) {
615        Out << "nil";
616        return false;
617      }
618    }
619
620    Out << IL->getValue();
621    return false;
622  }
623
624  return false;
625}
626
627PathDiagnosticPiece *
628ConditionBRVisitor::VisitTrueTest(const Expr *Cond,
629                                  const BinaryOperator *BExpr,
630                                  const bool tookTrue,
631                                  BugReporterContext &BRC,
632                                  BugReport &R,
633                                  const ExplodedNode *N) {
634
635  bool shouldInvert = false;
636  llvm::Optional<bool> shouldPrune;
637
638  SmallString<128> LhsString, RhsString;
639  {
640    llvm::raw_svector_ostream OutLHS(LhsString), OutRHS(RhsString);
641    const bool isVarLHS = patternMatch(BExpr->getLHS(), OutLHS, BRC, R, N,
642                                       shouldPrune);
643    const bool isVarRHS = patternMatch(BExpr->getRHS(), OutRHS, BRC, R, N,
644                                       shouldPrune);
645
646    shouldInvert = !isVarLHS && isVarRHS;
647  }
648
649  BinaryOperator::Opcode Op = BExpr->getOpcode();
650
651  if (BinaryOperator::isAssignmentOp(Op)) {
652    // For assignment operators, all that we care about is that the LHS
653    // evaluates to "true" or "false".
654    return VisitConditionVariable(LhsString, BExpr->getLHS(), tookTrue,
655                                  BRC, R, N);
656  }
657
658  // For non-assignment operations, we require that we can understand
659  // both the LHS and RHS.
660  if (LhsString.empty() || RhsString.empty())
661    return 0;
662
663  // Should we invert the strings if the LHS is not a variable name?
664  SmallString<256> buf;
665  llvm::raw_svector_ostream Out(buf);
666  Out << "Assuming " << (shouldInvert ? RhsString : LhsString) << " is ";
667
668  // Do we need to invert the opcode?
669  if (shouldInvert)
670    switch (Op) {
671      default: break;
672      case BO_LT: Op = BO_GT; break;
673      case BO_GT: Op = BO_LT; break;
674      case BO_LE: Op = BO_GE; break;
675      case BO_GE: Op = BO_LE; break;
676    }
677
678  if (!tookTrue)
679    switch (Op) {
680      case BO_EQ: Op = BO_NE; break;
681      case BO_NE: Op = BO_EQ; break;
682      case BO_LT: Op = BO_GE; break;
683      case BO_GT: Op = BO_LE; break;
684      case BO_LE: Op = BO_GT; break;
685      case BO_GE: Op = BO_LT; break;
686      default:
687        return 0;
688    }
689
690  switch (Op) {
691    case BO_EQ:
692      Out << "equal to ";
693      break;
694    case BO_NE:
695      Out << "not equal to ";
696      break;
697    default:
698      Out << BinaryOperator::getOpcodeStr(Op) << ' ';
699      break;
700  }
701
702  Out << (shouldInvert ? LhsString : RhsString);
703  const LocationContext *LCtx = N->getLocationContext();
704  PathDiagnosticLocation Loc(Cond, BRC.getSourceManager(), LCtx);
705  PathDiagnosticEventPiece *event =
706    new PathDiagnosticEventPiece(Loc, Out.str());
707  if (shouldPrune.hasValue())
708    event->setPrunable(shouldPrune.getValue());
709  return event;
710}
711
712PathDiagnosticPiece *
713ConditionBRVisitor::VisitConditionVariable(StringRef LhsString,
714                                           const Expr *CondVarExpr,
715                                           const bool tookTrue,
716                                           BugReporterContext &BRC,
717                                           BugReport &report,
718                                           const ExplodedNode *N) {
719  // FIXME: If there's already a constraint tracker for this variable,
720  // we shouldn't emit anything here (c.f. the double note in
721  // test/Analysis/inlining/path-notes.c)
722  SmallString<256> buf;
723  llvm::raw_svector_ostream Out(buf);
724  Out << "Assuming " << LhsString << " is ";
725
726  QualType Ty = CondVarExpr->getType();
727
728  if (Ty->isPointerType())
729    Out << (tookTrue ? "not null" : "null");
730  else if (Ty->isObjCObjectPointerType())
731    Out << (tookTrue ? "not nil" : "nil");
732  else if (Ty->isBooleanType())
733    Out << (tookTrue ? "true" : "false");
734  else if (Ty->isIntegerType())
735    Out << (tookTrue ? "non-zero" : "zero");
736  else
737    return 0;
738
739  const LocationContext *LCtx = N->getLocationContext();
740  PathDiagnosticLocation Loc(CondVarExpr, BRC.getSourceManager(), LCtx);
741  PathDiagnosticEventPiece *event =
742    new PathDiagnosticEventPiece(Loc, Out.str());
743
744  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(CondVarExpr)) {
745    if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
746      const ProgramState *state = N->getState().getPtr();
747      if (const MemRegion *R = state->getLValue(VD, LCtx).getAsRegion()) {
748        if (report.isInteresting(R))
749          event->setPrunable(false);
750      }
751    }
752  }
753
754  return event;
755}
756
757PathDiagnosticPiece *
758ConditionBRVisitor::VisitTrueTest(const Expr *Cond,
759                                  const DeclRefExpr *DR,
760                                  const bool tookTrue,
761                                  BugReporterContext &BRC,
762                                  BugReport &report,
763                                  const ExplodedNode *N) {
764
765  const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
766  if (!VD)
767    return 0;
768
769  SmallString<256> Buf;
770  llvm::raw_svector_ostream Out(Buf);
771
772  Out << "Assuming '";
773  VD->getDeclName().printName(Out);
774  Out << "' is ";
775
776  QualType VDTy = VD->getType();
777
778  if (VDTy->isPointerType())
779    Out << (tookTrue ? "non-null" : "null");
780  else if (VDTy->isObjCObjectPointerType())
781    Out << (tookTrue ? "non-nil" : "nil");
782  else if (VDTy->isScalarType())
783    Out << (tookTrue ? "not equal to 0" : "0");
784  else
785    return 0;
786
787  const LocationContext *LCtx = N->getLocationContext();
788  PathDiagnosticLocation Loc(Cond, BRC.getSourceManager(), LCtx);
789  PathDiagnosticEventPiece *event =
790    new PathDiagnosticEventPiece(Loc, Out.str());
791
792  const ProgramState *state = N->getState().getPtr();
793  if (const MemRegion *R = state->getLValue(VD, LCtx).getAsRegion()) {
794    if (report.isInteresting(R))
795      event->setPrunable(false);
796    else {
797      SVal V = state->getSVal(R);
798      if (report.isInteresting(V))
799        event->setPrunable(false);
800    }
801  }
802  return event;
803}
804
805