1//===- ThreadSafety.cpp ----------------------------------------*- 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// A intra-procedural analysis for thread safety (e.g. deadlocks and race
11// conditions), based off of an annotation system.
12//
13// See http://clang.llvm.org/docs/ThreadSafetyAnalysis.html
14// for more information.
15//
16//===----------------------------------------------------------------------===//
17
18#include "clang/AST/Attr.h"
19#include "clang/AST/DeclCXX.h"
20#include "clang/AST/ExprCXX.h"
21#include "clang/AST/StmtCXX.h"
22#include "clang/AST/StmtVisitor.h"
23#include "clang/Analysis/Analyses/PostOrderCFGView.h"
24#include "clang/Analysis/Analyses/ThreadSafety.h"
25#include "clang/Analysis/Analyses/ThreadSafetyCommon.h"
26#include "clang/Analysis/Analyses/ThreadSafetyLogical.h"
27#include "clang/Analysis/Analyses/ThreadSafetyTIL.h"
28#include "clang/Analysis/Analyses/ThreadSafetyTraverse.h"
29#include "clang/Analysis/AnalysisContext.h"
30#include "clang/Analysis/CFG.h"
31#include "clang/Analysis/CFGStmtMap.h"
32#include "clang/Basic/OperatorKinds.h"
33#include "clang/Basic/SourceLocation.h"
34#include "clang/Basic/SourceManager.h"
35#include "llvm/ADT/BitVector.h"
36#include "llvm/ADT/FoldingSet.h"
37#include "llvm/ADT/ImmutableMap.h"
38#include "llvm/ADT/PostOrderIterator.h"
39#include "llvm/ADT/SmallVector.h"
40#include "llvm/ADT/StringRef.h"
41#include "llvm/Support/raw_ostream.h"
42#include <algorithm>
43#include <ostream>
44#include <sstream>
45#include <utility>
46#include <vector>
47using namespace clang;
48using namespace threadSafety;
49
50// Key method definition
51ThreadSafetyHandler::~ThreadSafetyHandler() {}
52
53namespace {
54class TILPrinter :
55  public til::PrettyPrinter<TILPrinter, llvm::raw_ostream> {};
56
57
58/// Issue a warning about an invalid lock expression
59static void warnInvalidLock(ThreadSafetyHandler &Handler,
60                            const Expr *MutexExp, const NamedDecl *D,
61                            const Expr *DeclExp, StringRef Kind) {
62  SourceLocation Loc;
63  if (DeclExp)
64    Loc = DeclExp->getExprLoc();
65
66  // FIXME: add a note about the attribute location in MutexExp or D
67  if (Loc.isValid())
68    Handler.handleInvalidLockExp(Kind, Loc);
69}
70
71/// \brief A set of CapabilityInfo objects, which are compiled from the
72/// requires attributes on a function.
73class CapExprSet : public SmallVector<CapabilityExpr, 4> {
74public:
75  /// \brief Push M onto list, but discard duplicates.
76  void push_back_nodup(const CapabilityExpr &CapE) {
77    iterator It = std::find_if(begin(), end(),
78                               [=](const CapabilityExpr &CapE2) {
79      return CapE.equals(CapE2);
80    });
81    if (It == end())
82      push_back(CapE);
83  }
84};
85
86class FactManager;
87class FactSet;
88
89/// \brief This is a helper class that stores a fact that is known at a
90/// particular point in program execution.  Currently, a fact is a capability,
91/// along with additional information, such as where it was acquired, whether
92/// it is exclusive or shared, etc.
93///
94/// FIXME: this analysis does not currently support either re-entrant
95/// locking or lock "upgrading" and "downgrading" between exclusive and
96/// shared.
97class FactEntry : public CapabilityExpr {
98private:
99  LockKind          LKind;            ///<  exclusive or shared
100  SourceLocation    AcquireLoc;       ///<  where it was acquired.
101  bool              Asserted;         ///<  true if the lock was asserted
102  bool              Declared;         ///<  true if the lock was declared
103
104public:
105  FactEntry(const CapabilityExpr &CE, LockKind LK, SourceLocation Loc,
106            bool Asrt, bool Declrd = false)
107      : CapabilityExpr(CE), LKind(LK), AcquireLoc(Loc), Asserted(Asrt),
108        Declared(Declrd) {}
109
110  virtual ~FactEntry() {}
111
112  LockKind          kind()       const { return LKind;      }
113  SourceLocation    loc()        const { return AcquireLoc; }
114  bool              asserted()   const { return Asserted; }
115  bool              declared()   const { return Declared; }
116
117  void setDeclared(bool D) { Declared = D; }
118
119  virtual void
120  handleRemovalFromIntersection(const FactSet &FSet, FactManager &FactMan,
121                                SourceLocation JoinLoc, LockErrorKind LEK,
122                                ThreadSafetyHandler &Handler) const = 0;
123  virtual void handleUnlock(FactSet &FSet, FactManager &FactMan,
124                            const CapabilityExpr &Cp, SourceLocation UnlockLoc,
125                            bool FullyRemove, ThreadSafetyHandler &Handler,
126                            StringRef DiagKind) const = 0;
127
128  // Return true if LKind >= LK, where exclusive > shared
129  bool isAtLeast(LockKind LK) {
130    return  (LKind == LK_Exclusive) || (LK == LK_Shared);
131  }
132};
133
134
135typedef unsigned short FactID;
136
137/// \brief FactManager manages the memory for all facts that are created during
138/// the analysis of a single routine.
139class FactManager {
140private:
141  std::vector<std::unique_ptr<FactEntry>> Facts;
142
143public:
144  FactID newFact(std::unique_ptr<FactEntry> Entry) {
145    Facts.push_back(std::move(Entry));
146    return static_cast<unsigned short>(Facts.size() - 1);
147  }
148
149  const FactEntry &operator[](FactID F) const { return *Facts[F]; }
150  FactEntry &operator[](FactID F) { return *Facts[F]; }
151};
152
153
154/// \brief A FactSet is the set of facts that are known to be true at a
155/// particular program point.  FactSets must be small, because they are
156/// frequently copied, and are thus implemented as a set of indices into a
157/// table maintained by a FactManager.  A typical FactSet only holds 1 or 2
158/// locks, so we can get away with doing a linear search for lookup.  Note
159/// that a hashtable or map is inappropriate in this case, because lookups
160/// may involve partial pattern matches, rather than exact matches.
161class FactSet {
162private:
163  typedef SmallVector<FactID, 4> FactVec;
164
165  FactVec FactIDs;
166
167public:
168  typedef FactVec::iterator       iterator;
169  typedef FactVec::const_iterator const_iterator;
170
171  iterator       begin()       { return FactIDs.begin(); }
172  const_iterator begin() const { return FactIDs.begin(); }
173
174  iterator       end()       { return FactIDs.end(); }
175  const_iterator end() const { return FactIDs.end(); }
176
177  bool isEmpty() const { return FactIDs.size() == 0; }
178
179  // Return true if the set contains only negative facts
180  bool isEmpty(FactManager &FactMan) const {
181    for (FactID FID : *this) {
182      if (!FactMan[FID].negative())
183        return false;
184    }
185    return true;
186  }
187
188  void addLockByID(FactID ID) { FactIDs.push_back(ID); }
189
190  FactID addLock(FactManager &FM, std::unique_ptr<FactEntry> Entry) {
191    FactID F = FM.newFact(std::move(Entry));
192    FactIDs.push_back(F);
193    return F;
194  }
195
196  bool removeLock(FactManager& FM, const CapabilityExpr &CapE) {
197    unsigned n = FactIDs.size();
198    if (n == 0)
199      return false;
200
201    for (unsigned i = 0; i < n-1; ++i) {
202      if (FM[FactIDs[i]].matches(CapE)) {
203        FactIDs[i] = FactIDs[n-1];
204        FactIDs.pop_back();
205        return true;
206      }
207    }
208    if (FM[FactIDs[n-1]].matches(CapE)) {
209      FactIDs.pop_back();
210      return true;
211    }
212    return false;
213  }
214
215  iterator findLockIter(FactManager &FM, const CapabilityExpr &CapE) {
216    return std::find_if(begin(), end(), [&](FactID ID) {
217      return FM[ID].matches(CapE);
218    });
219  }
220
221  FactEntry *findLock(FactManager &FM, const CapabilityExpr &CapE) const {
222    auto I = std::find_if(begin(), end(), [&](FactID ID) {
223      return FM[ID].matches(CapE);
224    });
225    return I != end() ? &FM[*I] : nullptr;
226  }
227
228  FactEntry *findLockUniv(FactManager &FM, const CapabilityExpr &CapE) const {
229    auto I = std::find_if(begin(), end(), [&](FactID ID) -> bool {
230      return FM[ID].matchesUniv(CapE);
231    });
232    return I != end() ? &FM[*I] : nullptr;
233  }
234
235  FactEntry *findPartialMatch(FactManager &FM,
236                              const CapabilityExpr &CapE) const {
237    auto I = std::find_if(begin(), end(), [&](FactID ID) -> bool {
238      return FM[ID].partiallyMatches(CapE);
239    });
240    return I != end() ? &FM[*I] : nullptr;
241  }
242
243  bool containsMutexDecl(FactManager &FM, const ValueDecl* Vd) const {
244    auto I = std::find_if(begin(), end(), [&](FactID ID) -> bool {
245      return FM[ID].valueDecl() == Vd;
246    });
247    return I != end();
248  }
249};
250
251class ThreadSafetyAnalyzer;
252} // namespace
253
254namespace clang {
255namespace threadSafety {
256class BeforeSet {
257private:
258  typedef SmallVector<const ValueDecl*, 4>  BeforeVect;
259
260  struct BeforeInfo {
261    BeforeInfo() : Visited(0) {}
262    BeforeInfo(BeforeInfo &&O) : Vect(std::move(O.Vect)), Visited(O.Visited) {}
263
264    BeforeVect Vect;
265    int Visited;
266  };
267
268  typedef llvm::DenseMap<const ValueDecl *, std::unique_ptr<BeforeInfo>>
269      BeforeMap;
270  typedef llvm::DenseMap<const ValueDecl*, bool>        CycleMap;
271
272public:
273  BeforeSet() { }
274
275  BeforeInfo* insertAttrExprs(const ValueDecl* Vd,
276                              ThreadSafetyAnalyzer& Analyzer);
277
278  BeforeInfo *getBeforeInfoForDecl(const ValueDecl *Vd,
279                                   ThreadSafetyAnalyzer &Analyzer);
280
281  void checkBeforeAfter(const ValueDecl* Vd,
282                        const FactSet& FSet,
283                        ThreadSafetyAnalyzer& Analyzer,
284                        SourceLocation Loc, StringRef CapKind);
285
286private:
287  BeforeMap BMap;
288  CycleMap  CycMap;
289};
290} // end namespace threadSafety
291} // end namespace clang
292
293namespace {
294typedef llvm::ImmutableMap<const NamedDecl*, unsigned> LocalVarContext;
295class LocalVariableMap;
296
297/// A side (entry or exit) of a CFG node.
298enum CFGBlockSide { CBS_Entry, CBS_Exit };
299
300/// CFGBlockInfo is a struct which contains all the information that is
301/// maintained for each block in the CFG.  See LocalVariableMap for more
302/// information about the contexts.
303struct CFGBlockInfo {
304  FactSet EntrySet;             // Lockset held at entry to block
305  FactSet ExitSet;              // Lockset held at exit from block
306  LocalVarContext EntryContext; // Context held at entry to block
307  LocalVarContext ExitContext;  // Context held at exit from block
308  SourceLocation EntryLoc;      // Location of first statement in block
309  SourceLocation ExitLoc;       // Location of last statement in block.
310  unsigned EntryIndex;          // Used to replay contexts later
311  bool Reachable;               // Is this block reachable?
312
313  const FactSet &getSet(CFGBlockSide Side) const {
314    return Side == CBS_Entry ? EntrySet : ExitSet;
315  }
316  SourceLocation getLocation(CFGBlockSide Side) const {
317    return Side == CBS_Entry ? EntryLoc : ExitLoc;
318  }
319
320private:
321  CFGBlockInfo(LocalVarContext EmptyCtx)
322    : EntryContext(EmptyCtx), ExitContext(EmptyCtx), Reachable(false)
323  { }
324
325public:
326  static CFGBlockInfo getEmptyBlockInfo(LocalVariableMap &M);
327};
328
329
330
331// A LocalVariableMap maintains a map from local variables to their currently
332// valid definitions.  It provides SSA-like functionality when traversing the
333// CFG.  Like SSA, each definition or assignment to a variable is assigned a
334// unique name (an integer), which acts as the SSA name for that definition.
335// The total set of names is shared among all CFG basic blocks.
336// Unlike SSA, we do not rewrite expressions to replace local variables declrefs
337// with their SSA-names.  Instead, we compute a Context for each point in the
338// code, which maps local variables to the appropriate SSA-name.  This map
339// changes with each assignment.
340//
341// The map is computed in a single pass over the CFG.  Subsequent analyses can
342// then query the map to find the appropriate Context for a statement, and use
343// that Context to look up the definitions of variables.
344class LocalVariableMap {
345public:
346  typedef LocalVarContext Context;
347
348  /// A VarDefinition consists of an expression, representing the value of the
349  /// variable, along with the context in which that expression should be
350  /// interpreted.  A reference VarDefinition does not itself contain this
351  /// information, but instead contains a pointer to a previous VarDefinition.
352  struct VarDefinition {
353  public:
354    friend class LocalVariableMap;
355
356    const NamedDecl *Dec;  // The original declaration for this variable.
357    const Expr *Exp;       // The expression for this variable, OR
358    unsigned Ref;          // Reference to another VarDefinition
359    Context Ctx;           // The map with which Exp should be interpreted.
360
361    bool isReference() { return !Exp; }
362
363  private:
364    // Create ordinary variable definition
365    VarDefinition(const NamedDecl *D, const Expr *E, Context C)
366      : Dec(D), Exp(E), Ref(0), Ctx(C)
367    { }
368
369    // Create reference to previous definition
370    VarDefinition(const NamedDecl *D, unsigned R, Context C)
371      : Dec(D), Exp(nullptr), Ref(R), Ctx(C)
372    { }
373  };
374
375private:
376  Context::Factory ContextFactory;
377  std::vector<VarDefinition> VarDefinitions;
378  std::vector<unsigned> CtxIndices;
379  std::vector<std::pair<Stmt*, Context> > SavedContexts;
380
381public:
382  LocalVariableMap() {
383    // index 0 is a placeholder for undefined variables (aka phi-nodes).
384    VarDefinitions.push_back(VarDefinition(nullptr, 0u, getEmptyContext()));
385  }
386
387  /// Look up a definition, within the given context.
388  const VarDefinition* lookup(const NamedDecl *D, Context Ctx) {
389    const unsigned *i = Ctx.lookup(D);
390    if (!i)
391      return nullptr;
392    assert(*i < VarDefinitions.size());
393    return &VarDefinitions[*i];
394  }
395
396  /// Look up the definition for D within the given context.  Returns
397  /// NULL if the expression is not statically known.  If successful, also
398  /// modifies Ctx to hold the context of the return Expr.
399  const Expr* lookupExpr(const NamedDecl *D, Context &Ctx) {
400    const unsigned *P = Ctx.lookup(D);
401    if (!P)
402      return nullptr;
403
404    unsigned i = *P;
405    while (i > 0) {
406      if (VarDefinitions[i].Exp) {
407        Ctx = VarDefinitions[i].Ctx;
408        return VarDefinitions[i].Exp;
409      }
410      i = VarDefinitions[i].Ref;
411    }
412    return nullptr;
413  }
414
415  Context getEmptyContext() { return ContextFactory.getEmptyMap(); }
416
417  /// Return the next context after processing S.  This function is used by
418  /// clients of the class to get the appropriate context when traversing the
419  /// CFG.  It must be called for every assignment or DeclStmt.
420  Context getNextContext(unsigned &CtxIndex, Stmt *S, Context C) {
421    if (SavedContexts[CtxIndex+1].first == S) {
422      CtxIndex++;
423      Context Result = SavedContexts[CtxIndex].second;
424      return Result;
425    }
426    return C;
427  }
428
429  void dumpVarDefinitionName(unsigned i) {
430    if (i == 0) {
431      llvm::errs() << "Undefined";
432      return;
433    }
434    const NamedDecl *Dec = VarDefinitions[i].Dec;
435    if (!Dec) {
436      llvm::errs() << "<<NULL>>";
437      return;
438    }
439    Dec->printName(llvm::errs());
440    llvm::errs() << "." << i << " " << ((const void*) Dec);
441  }
442
443  /// Dumps an ASCII representation of the variable map to llvm::errs()
444  void dump() {
445    for (unsigned i = 1, e = VarDefinitions.size(); i < e; ++i) {
446      const Expr *Exp = VarDefinitions[i].Exp;
447      unsigned Ref = VarDefinitions[i].Ref;
448
449      dumpVarDefinitionName(i);
450      llvm::errs() << " = ";
451      if (Exp) Exp->dump();
452      else {
453        dumpVarDefinitionName(Ref);
454        llvm::errs() << "\n";
455      }
456    }
457  }
458
459  /// Dumps an ASCII representation of a Context to llvm::errs()
460  void dumpContext(Context C) {
461    for (Context::iterator I = C.begin(), E = C.end(); I != E; ++I) {
462      const NamedDecl *D = I.getKey();
463      D->printName(llvm::errs());
464      const unsigned *i = C.lookup(D);
465      llvm::errs() << " -> ";
466      dumpVarDefinitionName(*i);
467      llvm::errs() << "\n";
468    }
469  }
470
471  /// Builds the variable map.
472  void traverseCFG(CFG *CFGraph, const PostOrderCFGView *SortedGraph,
473                   std::vector<CFGBlockInfo> &BlockInfo);
474
475protected:
476  // Get the current context index
477  unsigned getContextIndex() { return SavedContexts.size()-1; }
478
479  // Save the current context for later replay
480  void saveContext(Stmt *S, Context C) {
481    SavedContexts.push_back(std::make_pair(S,C));
482  }
483
484  // Adds a new definition to the given context, and returns a new context.
485  // This method should be called when declaring a new variable.
486  Context addDefinition(const NamedDecl *D, const Expr *Exp, Context Ctx) {
487    assert(!Ctx.contains(D));
488    unsigned newID = VarDefinitions.size();
489    Context NewCtx = ContextFactory.add(Ctx, D, newID);
490    VarDefinitions.push_back(VarDefinition(D, Exp, Ctx));
491    return NewCtx;
492  }
493
494  // Add a new reference to an existing definition.
495  Context addReference(const NamedDecl *D, unsigned i, Context Ctx) {
496    unsigned newID = VarDefinitions.size();
497    Context NewCtx = ContextFactory.add(Ctx, D, newID);
498    VarDefinitions.push_back(VarDefinition(D, i, Ctx));
499    return NewCtx;
500  }
501
502  // Updates a definition only if that definition is already in the map.
503  // This method should be called when assigning to an existing variable.
504  Context updateDefinition(const NamedDecl *D, Expr *Exp, Context Ctx) {
505    if (Ctx.contains(D)) {
506      unsigned newID = VarDefinitions.size();
507      Context NewCtx = ContextFactory.remove(Ctx, D);
508      NewCtx = ContextFactory.add(NewCtx, D, newID);
509      VarDefinitions.push_back(VarDefinition(D, Exp, Ctx));
510      return NewCtx;
511    }
512    return Ctx;
513  }
514
515  // Removes a definition from the context, but keeps the variable name
516  // as a valid variable.  The index 0 is a placeholder for cleared definitions.
517  Context clearDefinition(const NamedDecl *D, Context Ctx) {
518    Context NewCtx = Ctx;
519    if (NewCtx.contains(D)) {
520      NewCtx = ContextFactory.remove(NewCtx, D);
521      NewCtx = ContextFactory.add(NewCtx, D, 0);
522    }
523    return NewCtx;
524  }
525
526  // Remove a definition entirely frmo the context.
527  Context removeDefinition(const NamedDecl *D, Context Ctx) {
528    Context NewCtx = Ctx;
529    if (NewCtx.contains(D)) {
530      NewCtx = ContextFactory.remove(NewCtx, D);
531    }
532    return NewCtx;
533  }
534
535  Context intersectContexts(Context C1, Context C2);
536  Context createReferenceContext(Context C);
537  void intersectBackEdge(Context C1, Context C2);
538
539  friend class VarMapBuilder;
540};
541
542
543// This has to be defined after LocalVariableMap.
544CFGBlockInfo CFGBlockInfo::getEmptyBlockInfo(LocalVariableMap &M) {
545  return CFGBlockInfo(M.getEmptyContext());
546}
547
548
549/// Visitor which builds a LocalVariableMap
550class VarMapBuilder : public StmtVisitor<VarMapBuilder> {
551public:
552  LocalVariableMap* VMap;
553  LocalVariableMap::Context Ctx;
554
555  VarMapBuilder(LocalVariableMap *VM, LocalVariableMap::Context C)
556    : VMap(VM), Ctx(C) {}
557
558  void VisitDeclStmt(DeclStmt *S);
559  void VisitBinaryOperator(BinaryOperator *BO);
560};
561
562
563// Add new local variables to the variable map
564void VarMapBuilder::VisitDeclStmt(DeclStmt *S) {
565  bool modifiedCtx = false;
566  DeclGroupRef DGrp = S->getDeclGroup();
567  for (const auto *D : DGrp) {
568    if (const auto *VD = dyn_cast_or_null<VarDecl>(D)) {
569      const Expr *E = VD->getInit();
570
571      // Add local variables with trivial type to the variable map
572      QualType T = VD->getType();
573      if (T.isTrivialType(VD->getASTContext())) {
574        Ctx = VMap->addDefinition(VD, E, Ctx);
575        modifiedCtx = true;
576      }
577    }
578  }
579  if (modifiedCtx)
580    VMap->saveContext(S, Ctx);
581}
582
583// Update local variable definitions in variable map
584void VarMapBuilder::VisitBinaryOperator(BinaryOperator *BO) {
585  if (!BO->isAssignmentOp())
586    return;
587
588  Expr *LHSExp = BO->getLHS()->IgnoreParenCasts();
589
590  // Update the variable map and current context.
591  if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(LHSExp)) {
592    ValueDecl *VDec = DRE->getDecl();
593    if (Ctx.lookup(VDec)) {
594      if (BO->getOpcode() == BO_Assign)
595        Ctx = VMap->updateDefinition(VDec, BO->getRHS(), Ctx);
596      else
597        // FIXME -- handle compound assignment operators
598        Ctx = VMap->clearDefinition(VDec, Ctx);
599      VMap->saveContext(BO, Ctx);
600    }
601  }
602}
603
604
605// Computes the intersection of two contexts.  The intersection is the
606// set of variables which have the same definition in both contexts;
607// variables with different definitions are discarded.
608LocalVariableMap::Context
609LocalVariableMap::intersectContexts(Context C1, Context C2) {
610  Context Result = C1;
611  for (const auto &P : C1) {
612    const NamedDecl *Dec = P.first;
613    const unsigned *i2 = C2.lookup(Dec);
614    if (!i2)             // variable doesn't exist on second path
615      Result = removeDefinition(Dec, Result);
616    else if (*i2 != P.second)  // variable exists, but has different definition
617      Result = clearDefinition(Dec, Result);
618  }
619  return Result;
620}
621
622// For every variable in C, create a new variable that refers to the
623// definition in C.  Return a new context that contains these new variables.
624// (We use this for a naive implementation of SSA on loop back-edges.)
625LocalVariableMap::Context LocalVariableMap::createReferenceContext(Context C) {
626  Context Result = getEmptyContext();
627  for (const auto &P : C)
628    Result = addReference(P.first, P.second, Result);
629  return Result;
630}
631
632// This routine also takes the intersection of C1 and C2, but it does so by
633// altering the VarDefinitions.  C1 must be the result of an earlier call to
634// createReferenceContext.
635void LocalVariableMap::intersectBackEdge(Context C1, Context C2) {
636  for (const auto &P : C1) {
637    unsigned i1 = P.second;
638    VarDefinition *VDef = &VarDefinitions[i1];
639    assert(VDef->isReference());
640
641    const unsigned *i2 = C2.lookup(P.first);
642    if (!i2 || (*i2 != i1))
643      VDef->Ref = 0;    // Mark this variable as undefined
644  }
645}
646
647
648// Traverse the CFG in topological order, so all predecessors of a block
649// (excluding back-edges) are visited before the block itself.  At
650// each point in the code, we calculate a Context, which holds the set of
651// variable definitions which are visible at that point in execution.
652// Visible variables are mapped to their definitions using an array that
653// contains all definitions.
654//
655// At join points in the CFG, the set is computed as the intersection of
656// the incoming sets along each edge, E.g.
657//
658//                       { Context                 | VarDefinitions }
659//   int x = 0;          { x -> x1                 | x1 = 0 }
660//   int y = 0;          { x -> x1, y -> y1        | y1 = 0, x1 = 0 }
661//   if (b) x = 1;       { x -> x2, y -> y1        | x2 = 1, y1 = 0, ... }
662//   else   x = 2;       { x -> x3, y -> y1        | x3 = 2, x2 = 1, ... }
663//   ...                 { y -> y1  (x is unknown) | x3 = 2, x2 = 1, ... }
664//
665// This is essentially a simpler and more naive version of the standard SSA
666// algorithm.  Those definitions that remain in the intersection are from blocks
667// that strictly dominate the current block.  We do not bother to insert proper
668// phi nodes, because they are not used in our analysis; instead, wherever
669// a phi node would be required, we simply remove that definition from the
670// context (E.g. x above).
671//
672// The initial traversal does not capture back-edges, so those need to be
673// handled on a separate pass.  Whenever the first pass encounters an
674// incoming back edge, it duplicates the context, creating new definitions
675// that refer back to the originals.  (These correspond to places where SSA
676// might have to insert a phi node.)  On the second pass, these definitions are
677// set to NULL if the variable has changed on the back-edge (i.e. a phi
678// node was actually required.)  E.g.
679//
680//                       { Context           | VarDefinitions }
681//   int x = 0, y = 0;   { x -> x1, y -> y1  | y1 = 0, x1 = 0 }
682//   while (b)           { x -> x2, y -> y1  | [1st:] x2=x1; [2nd:] x2=NULL; }
683//     x = x+1;          { x -> x3, y -> y1  | x3 = x2 + 1, ... }
684//   ...                 { y -> y1           | x3 = 2, x2 = 1, ... }
685//
686void LocalVariableMap::traverseCFG(CFG *CFGraph,
687                                   const PostOrderCFGView *SortedGraph,
688                                   std::vector<CFGBlockInfo> &BlockInfo) {
689  PostOrderCFGView::CFGBlockSet VisitedBlocks(CFGraph);
690
691  CtxIndices.resize(CFGraph->getNumBlockIDs());
692
693  for (const auto *CurrBlock : *SortedGraph) {
694    int CurrBlockID = CurrBlock->getBlockID();
695    CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlockID];
696
697    VisitedBlocks.insert(CurrBlock);
698
699    // Calculate the entry context for the current block
700    bool HasBackEdges = false;
701    bool CtxInit = true;
702    for (CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
703         PE  = CurrBlock->pred_end(); PI != PE; ++PI) {
704      // if *PI -> CurrBlock is a back edge, so skip it
705      if (*PI == nullptr || !VisitedBlocks.alreadySet(*PI)) {
706        HasBackEdges = true;
707        continue;
708      }
709
710      int PrevBlockID = (*PI)->getBlockID();
711      CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
712
713      if (CtxInit) {
714        CurrBlockInfo->EntryContext = PrevBlockInfo->ExitContext;
715        CtxInit = false;
716      }
717      else {
718        CurrBlockInfo->EntryContext =
719          intersectContexts(CurrBlockInfo->EntryContext,
720                            PrevBlockInfo->ExitContext);
721      }
722    }
723
724    // Duplicate the context if we have back-edges, so we can call
725    // intersectBackEdges later.
726    if (HasBackEdges)
727      CurrBlockInfo->EntryContext =
728        createReferenceContext(CurrBlockInfo->EntryContext);
729
730    // Create a starting context index for the current block
731    saveContext(nullptr, CurrBlockInfo->EntryContext);
732    CurrBlockInfo->EntryIndex = getContextIndex();
733
734    // Visit all the statements in the basic block.
735    VarMapBuilder VMapBuilder(this, CurrBlockInfo->EntryContext);
736    for (CFGBlock::const_iterator BI = CurrBlock->begin(),
737         BE = CurrBlock->end(); BI != BE; ++BI) {
738      switch (BI->getKind()) {
739        case CFGElement::Statement: {
740          CFGStmt CS = BI->castAs<CFGStmt>();
741          VMapBuilder.Visit(const_cast<Stmt*>(CS.getStmt()));
742          break;
743        }
744        default:
745          break;
746      }
747    }
748    CurrBlockInfo->ExitContext = VMapBuilder.Ctx;
749
750    // Mark variables on back edges as "unknown" if they've been changed.
751    for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
752         SE  = CurrBlock->succ_end(); SI != SE; ++SI) {
753      // if CurrBlock -> *SI is *not* a back edge
754      if (*SI == nullptr || !VisitedBlocks.alreadySet(*SI))
755        continue;
756
757      CFGBlock *FirstLoopBlock = *SI;
758      Context LoopBegin = BlockInfo[FirstLoopBlock->getBlockID()].EntryContext;
759      Context LoopEnd   = CurrBlockInfo->ExitContext;
760      intersectBackEdge(LoopBegin, LoopEnd);
761    }
762  }
763
764  // Put an extra entry at the end of the indexed context array
765  unsigned exitID = CFGraph->getExit().getBlockID();
766  saveContext(nullptr, BlockInfo[exitID].ExitContext);
767}
768
769/// Find the appropriate source locations to use when producing diagnostics for
770/// each block in the CFG.
771static void findBlockLocations(CFG *CFGraph,
772                               const PostOrderCFGView *SortedGraph,
773                               std::vector<CFGBlockInfo> &BlockInfo) {
774  for (const auto *CurrBlock : *SortedGraph) {
775    CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlock->getBlockID()];
776
777    // Find the source location of the last statement in the block, if the
778    // block is not empty.
779    if (const Stmt *S = CurrBlock->getTerminator()) {
780      CurrBlockInfo->EntryLoc = CurrBlockInfo->ExitLoc = S->getLocStart();
781    } else {
782      for (CFGBlock::const_reverse_iterator BI = CurrBlock->rbegin(),
783           BE = CurrBlock->rend(); BI != BE; ++BI) {
784        // FIXME: Handle other CFGElement kinds.
785        if (Optional<CFGStmt> CS = BI->getAs<CFGStmt>()) {
786          CurrBlockInfo->ExitLoc = CS->getStmt()->getLocStart();
787          break;
788        }
789      }
790    }
791
792    if (CurrBlockInfo->ExitLoc.isValid()) {
793      // This block contains at least one statement. Find the source location
794      // of the first statement in the block.
795      for (CFGBlock::const_iterator BI = CurrBlock->begin(),
796           BE = CurrBlock->end(); BI != BE; ++BI) {
797        // FIXME: Handle other CFGElement kinds.
798        if (Optional<CFGStmt> CS = BI->getAs<CFGStmt>()) {
799          CurrBlockInfo->EntryLoc = CS->getStmt()->getLocStart();
800          break;
801        }
802      }
803    } else if (CurrBlock->pred_size() == 1 && *CurrBlock->pred_begin() &&
804               CurrBlock != &CFGraph->getExit()) {
805      // The block is empty, and has a single predecessor. Use its exit
806      // location.
807      CurrBlockInfo->EntryLoc = CurrBlockInfo->ExitLoc =
808          BlockInfo[(*CurrBlock->pred_begin())->getBlockID()].ExitLoc;
809    }
810  }
811}
812
813class LockableFactEntry : public FactEntry {
814private:
815  bool Managed; ///<  managed by ScopedLockable object
816
817public:
818  LockableFactEntry(const CapabilityExpr &CE, LockKind LK, SourceLocation Loc,
819                    bool Mng = false, bool Asrt = false)
820      : FactEntry(CE, LK, Loc, Asrt), Managed(Mng) {}
821
822  void
823  handleRemovalFromIntersection(const FactSet &FSet, FactManager &FactMan,
824                                SourceLocation JoinLoc, LockErrorKind LEK,
825                                ThreadSafetyHandler &Handler) const override {
826    if (!Managed && !asserted() && !negative() && !isUniversal()) {
827      Handler.handleMutexHeldEndOfScope("mutex", toString(), loc(), JoinLoc,
828                                        LEK);
829    }
830  }
831
832  void handleUnlock(FactSet &FSet, FactManager &FactMan,
833                    const CapabilityExpr &Cp, SourceLocation UnlockLoc,
834                    bool FullyRemove, ThreadSafetyHandler &Handler,
835                    StringRef DiagKind) const override {
836    FSet.removeLock(FactMan, Cp);
837    if (!Cp.negative()) {
838      FSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
839                                !Cp, LK_Exclusive, UnlockLoc));
840    }
841  }
842};
843
844class ScopedLockableFactEntry : public FactEntry {
845private:
846  SmallVector<const til::SExpr *, 4> UnderlyingMutexes;
847
848public:
849  ScopedLockableFactEntry(const CapabilityExpr &CE, SourceLocation Loc,
850                          const CapExprSet &Excl, const CapExprSet &Shrd)
851      : FactEntry(CE, LK_Exclusive, Loc, false) {
852    for (const auto &M : Excl)
853      UnderlyingMutexes.push_back(M.sexpr());
854    for (const auto &M : Shrd)
855      UnderlyingMutexes.push_back(M.sexpr());
856  }
857
858  void
859  handleRemovalFromIntersection(const FactSet &FSet, FactManager &FactMan,
860                                SourceLocation JoinLoc, LockErrorKind LEK,
861                                ThreadSafetyHandler &Handler) const override {
862    for (const til::SExpr *UnderlyingMutex : UnderlyingMutexes) {
863      if (FSet.findLock(FactMan, CapabilityExpr(UnderlyingMutex, false))) {
864        // If this scoped lock manages another mutex, and if the underlying
865        // mutex is still held, then warn about the underlying mutex.
866        Handler.handleMutexHeldEndOfScope(
867            "mutex", sx::toString(UnderlyingMutex), loc(), JoinLoc, LEK);
868      }
869    }
870  }
871
872  void handleUnlock(FactSet &FSet, FactManager &FactMan,
873                    const CapabilityExpr &Cp, SourceLocation UnlockLoc,
874                    bool FullyRemove, ThreadSafetyHandler &Handler,
875                    StringRef DiagKind) const override {
876    assert(!Cp.negative() && "Managing object cannot be negative.");
877    for (const til::SExpr *UnderlyingMutex : UnderlyingMutexes) {
878      CapabilityExpr UnderCp(UnderlyingMutex, false);
879      auto UnderEntry = llvm::make_unique<LockableFactEntry>(
880          !UnderCp, LK_Exclusive, UnlockLoc);
881
882      if (FullyRemove) {
883        // We're destroying the managing object.
884        // Remove the underlying mutex if it exists; but don't warn.
885        if (FSet.findLock(FactMan, UnderCp)) {
886          FSet.removeLock(FactMan, UnderCp);
887          FSet.addLock(FactMan, std::move(UnderEntry));
888        }
889      } else {
890        // We're releasing the underlying mutex, but not destroying the
891        // managing object.  Warn on dual release.
892        if (!FSet.findLock(FactMan, UnderCp)) {
893          Handler.handleUnmatchedUnlock(DiagKind, UnderCp.toString(),
894                                        UnlockLoc);
895        }
896        FSet.removeLock(FactMan, UnderCp);
897        FSet.addLock(FactMan, std::move(UnderEntry));
898      }
899    }
900    if (FullyRemove)
901      FSet.removeLock(FactMan, Cp);
902  }
903};
904
905/// \brief Class which implements the core thread safety analysis routines.
906class ThreadSafetyAnalyzer {
907  friend class BuildLockset;
908  friend class threadSafety::BeforeSet;
909
910  llvm::BumpPtrAllocator Bpa;
911  threadSafety::til::MemRegionRef Arena;
912  threadSafety::SExprBuilder SxBuilder;
913
914  ThreadSafetyHandler       &Handler;
915  const CXXMethodDecl       *CurrentMethod;
916  LocalVariableMap          LocalVarMap;
917  FactManager               FactMan;
918  std::vector<CFGBlockInfo> BlockInfo;
919
920  BeforeSet* GlobalBeforeSet;
921
922public:
923  ThreadSafetyAnalyzer(ThreadSafetyHandler &H, BeforeSet* Bset)
924     : Arena(&Bpa), SxBuilder(Arena), Handler(H), GlobalBeforeSet(Bset) {}
925
926  bool inCurrentScope(const CapabilityExpr &CapE);
927
928  void addLock(FactSet &FSet, std::unique_ptr<FactEntry> Entry,
929               StringRef DiagKind, bool ReqAttr = false);
930  void removeLock(FactSet &FSet, const CapabilityExpr &CapE,
931                  SourceLocation UnlockLoc, bool FullyRemove, LockKind Kind,
932                  StringRef DiagKind);
933
934  template <typename AttrType>
935  void getMutexIDs(CapExprSet &Mtxs, AttrType *Attr, Expr *Exp,
936                   const NamedDecl *D, VarDecl *SelfDecl = nullptr);
937
938  template <class AttrType>
939  void getMutexIDs(CapExprSet &Mtxs, AttrType *Attr, Expr *Exp,
940                   const NamedDecl *D,
941                   const CFGBlock *PredBlock, const CFGBlock *CurrBlock,
942                   Expr *BrE, bool Neg);
943
944  const CallExpr* getTrylockCallExpr(const Stmt *Cond, LocalVarContext C,
945                                     bool &Negate);
946
947  void getEdgeLockset(FactSet &Result, const FactSet &ExitSet,
948                      const CFGBlock* PredBlock,
949                      const CFGBlock *CurrBlock);
950
951  void intersectAndWarn(FactSet &FSet1, const FactSet &FSet2,
952                        SourceLocation JoinLoc,
953                        LockErrorKind LEK1, LockErrorKind LEK2,
954                        bool Modify=true);
955
956  void intersectAndWarn(FactSet &FSet1, const FactSet &FSet2,
957                        SourceLocation JoinLoc, LockErrorKind LEK1,
958                        bool Modify=true) {
959    intersectAndWarn(FSet1, FSet2, JoinLoc, LEK1, LEK1, Modify);
960  }
961
962  void runAnalysis(AnalysisDeclContext &AC);
963};
964} // namespace
965
966/// Process acquired_before and acquired_after attributes on Vd.
967BeforeSet::BeforeInfo* BeforeSet::insertAttrExprs(const ValueDecl* Vd,
968    ThreadSafetyAnalyzer& Analyzer) {
969  // Create a new entry for Vd.
970  BeforeInfo *Info = nullptr;
971  {
972    // Keep InfoPtr in its own scope in case BMap is modified later and the
973    // reference becomes invalid.
974    std::unique_ptr<BeforeInfo> &InfoPtr = BMap[Vd];
975    if (!InfoPtr)
976      InfoPtr.reset(new BeforeInfo());
977    Info = InfoPtr.get();
978  }
979
980  for (Attr* At : Vd->attrs()) {
981    switch (At->getKind()) {
982      case attr::AcquiredBefore: {
983        auto *A = cast<AcquiredBeforeAttr>(At);
984
985        // Read exprs from the attribute, and add them to BeforeVect.
986        for (const auto *Arg : A->args()) {
987          CapabilityExpr Cp =
988            Analyzer.SxBuilder.translateAttrExpr(Arg, nullptr);
989          if (const ValueDecl *Cpvd = Cp.valueDecl()) {
990            Info->Vect.push_back(Cpvd);
991            auto It = BMap.find(Cpvd);
992            if (It == BMap.end())
993              insertAttrExprs(Cpvd, Analyzer);
994          }
995        }
996        break;
997      }
998      case attr::AcquiredAfter: {
999        auto *A = cast<AcquiredAfterAttr>(At);
1000
1001        // Read exprs from the attribute, and add them to BeforeVect.
1002        for (const auto *Arg : A->args()) {
1003          CapabilityExpr Cp =
1004            Analyzer.SxBuilder.translateAttrExpr(Arg, nullptr);
1005          if (const ValueDecl *ArgVd = Cp.valueDecl()) {
1006            // Get entry for mutex listed in attribute
1007            BeforeInfo *ArgInfo = getBeforeInfoForDecl(ArgVd, Analyzer);
1008            ArgInfo->Vect.push_back(Vd);
1009          }
1010        }
1011        break;
1012      }
1013      default:
1014        break;
1015    }
1016  }
1017
1018  return Info;
1019}
1020
1021BeforeSet::BeforeInfo *
1022BeforeSet::getBeforeInfoForDecl(const ValueDecl *Vd,
1023                                ThreadSafetyAnalyzer &Analyzer) {
1024  auto It = BMap.find(Vd);
1025  BeforeInfo *Info = nullptr;
1026  if (It == BMap.end())
1027    Info = insertAttrExprs(Vd, Analyzer);
1028  else
1029    Info = It->second.get();
1030  assert(Info && "BMap contained nullptr?");
1031  return Info;
1032}
1033
1034/// Return true if any mutexes in FSet are in the acquired_before set of Vd.
1035void BeforeSet::checkBeforeAfter(const ValueDecl* StartVd,
1036                                 const FactSet& FSet,
1037                                 ThreadSafetyAnalyzer& Analyzer,
1038                                 SourceLocation Loc, StringRef CapKind) {
1039  SmallVector<BeforeInfo*, 8> InfoVect;
1040
1041  // Do a depth-first traversal of Vd.
1042  // Return true if there are cycles.
1043  std::function<bool (const ValueDecl*)> traverse = [&](const ValueDecl* Vd) {
1044    if (!Vd)
1045      return false;
1046
1047    BeforeSet::BeforeInfo *Info = getBeforeInfoForDecl(Vd, Analyzer);
1048
1049    if (Info->Visited == 1)
1050      return true;
1051
1052    if (Info->Visited == 2)
1053      return false;
1054
1055    if (Info->Vect.empty())
1056      return false;
1057
1058    InfoVect.push_back(Info);
1059    Info->Visited = 1;
1060    for (auto *Vdb : Info->Vect) {
1061      // Exclude mutexes in our immediate before set.
1062      if (FSet.containsMutexDecl(Analyzer.FactMan, Vdb)) {
1063        StringRef L1 = StartVd->getName();
1064        StringRef L2 = Vdb->getName();
1065        Analyzer.Handler.handleLockAcquiredBefore(CapKind, L1, L2, Loc);
1066      }
1067      // Transitively search other before sets, and warn on cycles.
1068      if (traverse(Vdb)) {
1069        if (CycMap.find(Vd) == CycMap.end()) {
1070          CycMap.insert(std::make_pair(Vd, true));
1071          StringRef L1 = Vd->getName();
1072          Analyzer.Handler.handleBeforeAfterCycle(L1, Vd->getLocation());
1073        }
1074      }
1075    }
1076    Info->Visited = 2;
1077    return false;
1078  };
1079
1080  traverse(StartVd);
1081
1082  for (auto* Info : InfoVect)
1083    Info->Visited = 0;
1084}
1085
1086
1087
1088/// \brief Gets the value decl pointer from DeclRefExprs or MemberExprs.
1089static const ValueDecl *getValueDecl(const Expr *Exp) {
1090  if (const auto *CE = dyn_cast<ImplicitCastExpr>(Exp))
1091    return getValueDecl(CE->getSubExpr());
1092
1093  if (const auto *DR = dyn_cast<DeclRefExpr>(Exp))
1094    return DR->getDecl();
1095
1096  if (const auto *ME = dyn_cast<MemberExpr>(Exp))
1097    return ME->getMemberDecl();
1098
1099  return nullptr;
1100}
1101
1102namespace {
1103template <typename Ty>
1104class has_arg_iterator_range {
1105  typedef char yes[1];
1106  typedef char no[2];
1107
1108  template <typename Inner>
1109  static yes& test(Inner *I, decltype(I->args()) * = nullptr);
1110
1111  template <typename>
1112  static no& test(...);
1113
1114public:
1115  static const bool value = sizeof(test<Ty>(nullptr)) == sizeof(yes);
1116};
1117} // namespace
1118
1119static StringRef ClassifyDiagnostic(const CapabilityAttr *A) {
1120  return A->getName();
1121}
1122
1123static StringRef ClassifyDiagnostic(QualType VDT) {
1124  // We need to look at the declaration of the type of the value to determine
1125  // which it is. The type should either be a record or a typedef, or a pointer
1126  // or reference thereof.
1127  if (const auto *RT = VDT->getAs<RecordType>()) {
1128    if (const auto *RD = RT->getDecl())
1129      if (const auto *CA = RD->getAttr<CapabilityAttr>())
1130        return ClassifyDiagnostic(CA);
1131  } else if (const auto *TT = VDT->getAs<TypedefType>()) {
1132    if (const auto *TD = TT->getDecl())
1133      if (const auto *CA = TD->getAttr<CapabilityAttr>())
1134        return ClassifyDiagnostic(CA);
1135  } else if (VDT->isPointerType() || VDT->isReferenceType())
1136    return ClassifyDiagnostic(VDT->getPointeeType());
1137
1138  return "mutex";
1139}
1140
1141static StringRef ClassifyDiagnostic(const ValueDecl *VD) {
1142  assert(VD && "No ValueDecl passed");
1143
1144  // The ValueDecl is the declaration of a mutex or role (hopefully).
1145  return ClassifyDiagnostic(VD->getType());
1146}
1147
1148template <typename AttrTy>
1149static typename std::enable_if<!has_arg_iterator_range<AttrTy>::value,
1150                               StringRef>::type
1151ClassifyDiagnostic(const AttrTy *A) {
1152  if (const ValueDecl *VD = getValueDecl(A->getArg()))
1153    return ClassifyDiagnostic(VD);
1154  return "mutex";
1155}
1156
1157template <typename AttrTy>
1158static typename std::enable_if<has_arg_iterator_range<AttrTy>::value,
1159                               StringRef>::type
1160ClassifyDiagnostic(const AttrTy *A) {
1161  for (const auto *Arg : A->args()) {
1162    if (const ValueDecl *VD = getValueDecl(Arg))
1163      return ClassifyDiagnostic(VD);
1164  }
1165  return "mutex";
1166}
1167
1168
1169inline bool ThreadSafetyAnalyzer::inCurrentScope(const CapabilityExpr &CapE) {
1170  if (!CurrentMethod)
1171      return false;
1172  if (auto *P = dyn_cast_or_null<til::Project>(CapE.sexpr())) {
1173    auto *VD = P->clangDecl();
1174    if (VD)
1175      return VD->getDeclContext() == CurrentMethod->getDeclContext();
1176  }
1177  return false;
1178}
1179
1180
1181/// \brief Add a new lock to the lockset, warning if the lock is already there.
1182/// \param ReqAttr -- true if this is part of an initial Requires attribute.
1183void ThreadSafetyAnalyzer::addLock(FactSet &FSet,
1184                                   std::unique_ptr<FactEntry> Entry,
1185                                   StringRef DiagKind, bool ReqAttr) {
1186  if (Entry->shouldIgnore())
1187    return;
1188
1189  if (!ReqAttr && !Entry->negative()) {
1190    // look for the negative capability, and remove it from the fact set.
1191    CapabilityExpr NegC = !*Entry;
1192    FactEntry *Nen = FSet.findLock(FactMan, NegC);
1193    if (Nen) {
1194      FSet.removeLock(FactMan, NegC);
1195    }
1196    else {
1197      if (inCurrentScope(*Entry) && !Entry->asserted())
1198        Handler.handleNegativeNotHeld(DiagKind, Entry->toString(),
1199                                      NegC.toString(), Entry->loc());
1200    }
1201  }
1202
1203  // Check before/after constraints
1204  if (Handler.issueBetaWarnings() &&
1205      !Entry->asserted() && !Entry->declared()) {
1206    GlobalBeforeSet->checkBeforeAfter(Entry->valueDecl(), FSet, *this,
1207                                      Entry->loc(), DiagKind);
1208  }
1209
1210  // FIXME: Don't always warn when we have support for reentrant locks.
1211  if (FSet.findLock(FactMan, *Entry)) {
1212    if (!Entry->asserted())
1213      Handler.handleDoubleLock(DiagKind, Entry->toString(), Entry->loc());
1214  } else {
1215    FSet.addLock(FactMan, std::move(Entry));
1216  }
1217}
1218
1219
1220/// \brief Remove a lock from the lockset, warning if the lock is not there.
1221/// \param UnlockLoc The source location of the unlock (only used in error msg)
1222void ThreadSafetyAnalyzer::removeLock(FactSet &FSet, const CapabilityExpr &Cp,
1223                                      SourceLocation UnlockLoc,
1224                                      bool FullyRemove, LockKind ReceivedKind,
1225                                      StringRef DiagKind) {
1226  if (Cp.shouldIgnore())
1227    return;
1228
1229  const FactEntry *LDat = FSet.findLock(FactMan, Cp);
1230  if (!LDat) {
1231    Handler.handleUnmatchedUnlock(DiagKind, Cp.toString(), UnlockLoc);
1232    return;
1233  }
1234
1235  // Generic lock removal doesn't care about lock kind mismatches, but
1236  // otherwise diagnose when the lock kinds are mismatched.
1237  if (ReceivedKind != LK_Generic && LDat->kind() != ReceivedKind) {
1238    Handler.handleIncorrectUnlockKind(DiagKind, Cp.toString(),
1239                                      LDat->kind(), ReceivedKind, UnlockLoc);
1240  }
1241
1242  LDat->handleUnlock(FSet, FactMan, Cp, UnlockLoc, FullyRemove, Handler,
1243                     DiagKind);
1244}
1245
1246
1247/// \brief Extract the list of mutexIDs from the attribute on an expression,
1248/// and push them onto Mtxs, discarding any duplicates.
1249template <typename AttrType>
1250void ThreadSafetyAnalyzer::getMutexIDs(CapExprSet &Mtxs, AttrType *Attr,
1251                                       Expr *Exp, const NamedDecl *D,
1252                                       VarDecl *SelfDecl) {
1253  if (Attr->args_size() == 0) {
1254    // The mutex held is the "this" object.
1255    CapabilityExpr Cp = SxBuilder.translateAttrExpr(nullptr, D, Exp, SelfDecl);
1256    if (Cp.isInvalid()) {
1257       warnInvalidLock(Handler, nullptr, D, Exp, ClassifyDiagnostic(Attr));
1258       return;
1259    }
1260    //else
1261    if (!Cp.shouldIgnore())
1262      Mtxs.push_back_nodup(Cp);
1263    return;
1264  }
1265
1266  for (const auto *Arg : Attr->args()) {
1267    CapabilityExpr Cp = SxBuilder.translateAttrExpr(Arg, D, Exp, SelfDecl);
1268    if (Cp.isInvalid()) {
1269       warnInvalidLock(Handler, nullptr, D, Exp, ClassifyDiagnostic(Attr));
1270       continue;
1271    }
1272    //else
1273    if (!Cp.shouldIgnore())
1274      Mtxs.push_back_nodup(Cp);
1275  }
1276}
1277
1278
1279/// \brief Extract the list of mutexIDs from a trylock attribute.  If the
1280/// trylock applies to the given edge, then push them onto Mtxs, discarding
1281/// any duplicates.
1282template <class AttrType>
1283void ThreadSafetyAnalyzer::getMutexIDs(CapExprSet &Mtxs, AttrType *Attr,
1284                                       Expr *Exp, const NamedDecl *D,
1285                                       const CFGBlock *PredBlock,
1286                                       const CFGBlock *CurrBlock,
1287                                       Expr *BrE, bool Neg) {
1288  // Find out which branch has the lock
1289  bool branch = false;
1290  if (CXXBoolLiteralExpr *BLE = dyn_cast_or_null<CXXBoolLiteralExpr>(BrE))
1291    branch = BLE->getValue();
1292  else if (IntegerLiteral *ILE = dyn_cast_or_null<IntegerLiteral>(BrE))
1293    branch = ILE->getValue().getBoolValue();
1294
1295  int branchnum = branch ? 0 : 1;
1296  if (Neg)
1297    branchnum = !branchnum;
1298
1299  // If we've taken the trylock branch, then add the lock
1300  int i = 0;
1301  for (CFGBlock::const_succ_iterator SI = PredBlock->succ_begin(),
1302       SE = PredBlock->succ_end(); SI != SE && i < 2; ++SI, ++i) {
1303    if (*SI == CurrBlock && i == branchnum)
1304      getMutexIDs(Mtxs, Attr, Exp, D);
1305  }
1306}
1307
1308static bool getStaticBooleanValue(Expr *E, bool &TCond) {
1309  if (isa<CXXNullPtrLiteralExpr>(E) || isa<GNUNullExpr>(E)) {
1310    TCond = false;
1311    return true;
1312  } else if (CXXBoolLiteralExpr *BLE = dyn_cast<CXXBoolLiteralExpr>(E)) {
1313    TCond = BLE->getValue();
1314    return true;
1315  } else if (IntegerLiteral *ILE = dyn_cast<IntegerLiteral>(E)) {
1316    TCond = ILE->getValue().getBoolValue();
1317    return true;
1318  } else if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
1319    return getStaticBooleanValue(CE->getSubExpr(), TCond);
1320  }
1321  return false;
1322}
1323
1324
1325// If Cond can be traced back to a function call, return the call expression.
1326// The negate variable should be called with false, and will be set to true
1327// if the function call is negated, e.g. if (!mu.tryLock(...))
1328const CallExpr* ThreadSafetyAnalyzer::getTrylockCallExpr(const Stmt *Cond,
1329                                                         LocalVarContext C,
1330                                                         bool &Negate) {
1331  if (!Cond)
1332    return nullptr;
1333
1334  if (const CallExpr *CallExp = dyn_cast<CallExpr>(Cond)) {
1335    return CallExp;
1336  }
1337  else if (const ParenExpr *PE = dyn_cast<ParenExpr>(Cond)) {
1338    return getTrylockCallExpr(PE->getSubExpr(), C, Negate);
1339  }
1340  else if (const ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(Cond)) {
1341    return getTrylockCallExpr(CE->getSubExpr(), C, Negate);
1342  }
1343  else if (const ExprWithCleanups* EWC = dyn_cast<ExprWithCleanups>(Cond)) {
1344    return getTrylockCallExpr(EWC->getSubExpr(), C, Negate);
1345  }
1346  else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Cond)) {
1347    const Expr *E = LocalVarMap.lookupExpr(DRE->getDecl(), C);
1348    return getTrylockCallExpr(E, C, Negate);
1349  }
1350  else if (const UnaryOperator *UOP = dyn_cast<UnaryOperator>(Cond)) {
1351    if (UOP->getOpcode() == UO_LNot) {
1352      Negate = !Negate;
1353      return getTrylockCallExpr(UOP->getSubExpr(), C, Negate);
1354    }
1355    return nullptr;
1356  }
1357  else if (const BinaryOperator *BOP = dyn_cast<BinaryOperator>(Cond)) {
1358    if (BOP->getOpcode() == BO_EQ || BOP->getOpcode() == BO_NE) {
1359      if (BOP->getOpcode() == BO_NE)
1360        Negate = !Negate;
1361
1362      bool TCond = false;
1363      if (getStaticBooleanValue(BOP->getRHS(), TCond)) {
1364        if (!TCond) Negate = !Negate;
1365        return getTrylockCallExpr(BOP->getLHS(), C, Negate);
1366      }
1367      TCond = false;
1368      if (getStaticBooleanValue(BOP->getLHS(), TCond)) {
1369        if (!TCond) Negate = !Negate;
1370        return getTrylockCallExpr(BOP->getRHS(), C, Negate);
1371      }
1372      return nullptr;
1373    }
1374    if (BOP->getOpcode() == BO_LAnd) {
1375      // LHS must have been evaluated in a different block.
1376      return getTrylockCallExpr(BOP->getRHS(), C, Negate);
1377    }
1378    if (BOP->getOpcode() == BO_LOr) {
1379      return getTrylockCallExpr(BOP->getRHS(), C, Negate);
1380    }
1381    return nullptr;
1382  }
1383  return nullptr;
1384}
1385
1386
1387/// \brief Find the lockset that holds on the edge between PredBlock
1388/// and CurrBlock.  The edge set is the exit set of PredBlock (passed
1389/// as the ExitSet parameter) plus any trylocks, which are conditionally held.
1390void ThreadSafetyAnalyzer::getEdgeLockset(FactSet& Result,
1391                                          const FactSet &ExitSet,
1392                                          const CFGBlock *PredBlock,
1393                                          const CFGBlock *CurrBlock) {
1394  Result = ExitSet;
1395
1396  const Stmt *Cond = PredBlock->getTerminatorCondition();
1397  if (!Cond)
1398    return;
1399
1400  bool Negate = false;
1401  const CFGBlockInfo *PredBlockInfo = &BlockInfo[PredBlock->getBlockID()];
1402  const LocalVarContext &LVarCtx = PredBlockInfo->ExitContext;
1403  StringRef CapDiagKind = "mutex";
1404
1405  CallExpr *Exp =
1406    const_cast<CallExpr*>(getTrylockCallExpr(Cond, LVarCtx, Negate));
1407  if (!Exp)
1408    return;
1409
1410  NamedDecl *FunDecl = dyn_cast_or_null<NamedDecl>(Exp->getCalleeDecl());
1411  if(!FunDecl || !FunDecl->hasAttrs())
1412    return;
1413
1414  CapExprSet ExclusiveLocksToAdd;
1415  CapExprSet SharedLocksToAdd;
1416
1417  // If the condition is a call to a Trylock function, then grab the attributes
1418  for (auto *Attr : FunDecl->attrs()) {
1419    switch (Attr->getKind()) {
1420      case attr::ExclusiveTrylockFunction: {
1421        ExclusiveTrylockFunctionAttr *A =
1422          cast<ExclusiveTrylockFunctionAttr>(Attr);
1423        getMutexIDs(ExclusiveLocksToAdd, A, Exp, FunDecl,
1424                    PredBlock, CurrBlock, A->getSuccessValue(), Negate);
1425        CapDiagKind = ClassifyDiagnostic(A);
1426        break;
1427      }
1428      case attr::SharedTrylockFunction: {
1429        SharedTrylockFunctionAttr *A =
1430          cast<SharedTrylockFunctionAttr>(Attr);
1431        getMutexIDs(SharedLocksToAdd, A, Exp, FunDecl,
1432                    PredBlock, CurrBlock, A->getSuccessValue(), Negate);
1433        CapDiagKind = ClassifyDiagnostic(A);
1434        break;
1435      }
1436      default:
1437        break;
1438    }
1439  }
1440
1441  // Add and remove locks.
1442  SourceLocation Loc = Exp->getExprLoc();
1443  for (const auto &ExclusiveLockToAdd : ExclusiveLocksToAdd)
1444    addLock(Result, llvm::make_unique<LockableFactEntry>(ExclusiveLockToAdd,
1445                                                         LK_Exclusive, Loc),
1446            CapDiagKind);
1447  for (const auto &SharedLockToAdd : SharedLocksToAdd)
1448    addLock(Result, llvm::make_unique<LockableFactEntry>(SharedLockToAdd,
1449                                                         LK_Shared, Loc),
1450            CapDiagKind);
1451}
1452
1453namespace {
1454/// \brief We use this class to visit different types of expressions in
1455/// CFGBlocks, and build up the lockset.
1456/// An expression may cause us to add or remove locks from the lockset, or else
1457/// output error messages related to missing locks.
1458/// FIXME: In future, we may be able to not inherit from a visitor.
1459class BuildLockset : public StmtVisitor<BuildLockset> {
1460  friend class ThreadSafetyAnalyzer;
1461
1462  ThreadSafetyAnalyzer *Analyzer;
1463  FactSet FSet;
1464  LocalVariableMap::Context LVarCtx;
1465  unsigned CtxIndex;
1466
1467  // helper functions
1468  void warnIfMutexNotHeld(const NamedDecl *D, const Expr *Exp, AccessKind AK,
1469                          Expr *MutexExp, ProtectedOperationKind POK,
1470                          StringRef DiagKind, SourceLocation Loc);
1471  void warnIfMutexHeld(const NamedDecl *D, const Expr *Exp, Expr *MutexExp,
1472                       StringRef DiagKind);
1473
1474  void checkAccess(const Expr *Exp, AccessKind AK,
1475                   ProtectedOperationKind POK = POK_VarAccess);
1476  void checkPtAccess(const Expr *Exp, AccessKind AK,
1477                     ProtectedOperationKind POK = POK_VarAccess);
1478
1479  void handleCall(Expr *Exp, const NamedDecl *D, VarDecl *VD = nullptr);
1480
1481public:
1482  BuildLockset(ThreadSafetyAnalyzer *Anlzr, CFGBlockInfo &Info)
1483    : StmtVisitor<BuildLockset>(),
1484      Analyzer(Anlzr),
1485      FSet(Info.EntrySet),
1486      LVarCtx(Info.EntryContext),
1487      CtxIndex(Info.EntryIndex)
1488  {}
1489
1490  void VisitUnaryOperator(UnaryOperator *UO);
1491  void VisitBinaryOperator(BinaryOperator *BO);
1492  void VisitCastExpr(CastExpr *CE);
1493  void VisitCallExpr(CallExpr *Exp);
1494  void VisitCXXConstructExpr(CXXConstructExpr *Exp);
1495  void VisitDeclStmt(DeclStmt *S);
1496};
1497} // namespace
1498
1499/// \brief Warn if the LSet does not contain a lock sufficient to protect access
1500/// of at least the passed in AccessKind.
1501void BuildLockset::warnIfMutexNotHeld(const NamedDecl *D, const Expr *Exp,
1502                                      AccessKind AK, Expr *MutexExp,
1503                                      ProtectedOperationKind POK,
1504                                      StringRef DiagKind, SourceLocation Loc) {
1505  LockKind LK = getLockKindFromAccessKind(AK);
1506
1507  CapabilityExpr Cp = Analyzer->SxBuilder.translateAttrExpr(MutexExp, D, Exp);
1508  if (Cp.isInvalid()) {
1509    warnInvalidLock(Analyzer->Handler, MutexExp, D, Exp, DiagKind);
1510    return;
1511  } else if (Cp.shouldIgnore()) {
1512    return;
1513  }
1514
1515  if (Cp.negative()) {
1516    // Negative capabilities act like locks excluded
1517    FactEntry *LDat = FSet.findLock(Analyzer->FactMan, !Cp);
1518    if (LDat) {
1519      Analyzer->Handler.handleFunExcludesLock(
1520          DiagKind, D->getNameAsString(), (!Cp).toString(), Loc);
1521      return;
1522    }
1523
1524    // If this does not refer to a negative capability in the same class,
1525    // then stop here.
1526    if (!Analyzer->inCurrentScope(Cp))
1527      return;
1528
1529    // Otherwise the negative requirement must be propagated to the caller.
1530    LDat = FSet.findLock(Analyzer->FactMan, Cp);
1531    if (!LDat) {
1532      Analyzer->Handler.handleMutexNotHeld("", D, POK, Cp.toString(),
1533                                           LK_Shared, Loc);
1534    }
1535    return;
1536  }
1537
1538  FactEntry* LDat = FSet.findLockUniv(Analyzer->FactMan, Cp);
1539  bool NoError = true;
1540  if (!LDat) {
1541    // No exact match found.  Look for a partial match.
1542    LDat = FSet.findPartialMatch(Analyzer->FactMan, Cp);
1543    if (LDat) {
1544      // Warn that there's no precise match.
1545      std::string PartMatchStr = LDat->toString();
1546      StringRef   PartMatchName(PartMatchStr);
1547      Analyzer->Handler.handleMutexNotHeld(DiagKind, D, POK, Cp.toString(),
1548                                           LK, Loc, &PartMatchName);
1549    } else {
1550      // Warn that there's no match at all.
1551      Analyzer->Handler.handleMutexNotHeld(DiagKind, D, POK, Cp.toString(),
1552                                           LK, Loc);
1553    }
1554    NoError = false;
1555  }
1556  // Make sure the mutex we found is the right kind.
1557  if (NoError && LDat && !LDat->isAtLeast(LK)) {
1558    Analyzer->Handler.handleMutexNotHeld(DiagKind, D, POK, Cp.toString(),
1559                                         LK, Loc);
1560  }
1561}
1562
1563/// \brief Warn if the LSet contains the given lock.
1564void BuildLockset::warnIfMutexHeld(const NamedDecl *D, const Expr *Exp,
1565                                   Expr *MutexExp, StringRef DiagKind) {
1566  CapabilityExpr Cp = Analyzer->SxBuilder.translateAttrExpr(MutexExp, D, Exp);
1567  if (Cp.isInvalid()) {
1568    warnInvalidLock(Analyzer->Handler, MutexExp, D, Exp, DiagKind);
1569    return;
1570  } else if (Cp.shouldIgnore()) {
1571    return;
1572  }
1573
1574  FactEntry* LDat = FSet.findLock(Analyzer->FactMan, Cp);
1575  if (LDat) {
1576    Analyzer->Handler.handleFunExcludesLock(
1577        DiagKind, D->getNameAsString(), Cp.toString(), Exp->getExprLoc());
1578  }
1579}
1580
1581/// \brief Checks guarded_by and pt_guarded_by attributes.
1582/// Whenever we identify an access (read or write) to a DeclRefExpr that is
1583/// marked with guarded_by, we must ensure the appropriate mutexes are held.
1584/// Similarly, we check if the access is to an expression that dereferences
1585/// a pointer marked with pt_guarded_by.
1586void BuildLockset::checkAccess(const Expr *Exp, AccessKind AK,
1587                               ProtectedOperationKind POK) {
1588  Exp = Exp->IgnoreParenCasts();
1589
1590  SourceLocation Loc = Exp->getExprLoc();
1591
1592  // Local variables of reference type cannot be re-assigned;
1593  // map them to their initializer.
1594  while (const auto *DRE = dyn_cast<DeclRefExpr>(Exp)) {
1595    const auto *VD = dyn_cast<VarDecl>(DRE->getDecl()->getCanonicalDecl());
1596    if (VD && VD->isLocalVarDecl() && VD->getType()->isReferenceType()) {
1597      if (const auto *E = VD->getInit()) {
1598        Exp = E;
1599        continue;
1600      }
1601    }
1602    break;
1603  }
1604
1605  if (const UnaryOperator *UO = dyn_cast<UnaryOperator>(Exp)) {
1606    // For dereferences
1607    if (UO->getOpcode() == clang::UO_Deref)
1608      checkPtAccess(UO->getSubExpr(), AK, POK);
1609    return;
1610  }
1611
1612  if (const ArraySubscriptExpr *AE = dyn_cast<ArraySubscriptExpr>(Exp)) {
1613    checkPtAccess(AE->getLHS(), AK, POK);
1614    return;
1615  }
1616
1617  if (const MemberExpr *ME = dyn_cast<MemberExpr>(Exp)) {
1618    if (ME->isArrow())
1619      checkPtAccess(ME->getBase(), AK, POK);
1620    else
1621      checkAccess(ME->getBase(), AK, POK);
1622  }
1623
1624  const ValueDecl *D = getValueDecl(Exp);
1625  if (!D || !D->hasAttrs())
1626    return;
1627
1628  if (D->hasAttr<GuardedVarAttr>() && FSet.isEmpty(Analyzer->FactMan)) {
1629    Analyzer->Handler.handleNoMutexHeld("mutex", D, POK, AK, Loc);
1630  }
1631
1632  for (const auto *I : D->specific_attrs<GuardedByAttr>())
1633    warnIfMutexNotHeld(D, Exp, AK, I->getArg(), POK,
1634                       ClassifyDiagnostic(I), Loc);
1635}
1636
1637
1638/// \brief Checks pt_guarded_by and pt_guarded_var attributes.
1639/// POK is the same  operationKind that was passed to checkAccess.
1640void BuildLockset::checkPtAccess(const Expr *Exp, AccessKind AK,
1641                                 ProtectedOperationKind POK) {
1642  while (true) {
1643    if (const ParenExpr *PE = dyn_cast<ParenExpr>(Exp)) {
1644      Exp = PE->getSubExpr();
1645      continue;
1646    }
1647    if (const CastExpr *CE = dyn_cast<CastExpr>(Exp)) {
1648      if (CE->getCastKind() == CK_ArrayToPointerDecay) {
1649        // If it's an actual array, and not a pointer, then it's elements
1650        // are protected by GUARDED_BY, not PT_GUARDED_BY;
1651        checkAccess(CE->getSubExpr(), AK, POK);
1652        return;
1653      }
1654      Exp = CE->getSubExpr();
1655      continue;
1656    }
1657    break;
1658  }
1659
1660  // Pass by reference warnings are under a different flag.
1661  ProtectedOperationKind PtPOK = POK_VarDereference;
1662  if (POK == POK_PassByRef) PtPOK = POK_PtPassByRef;
1663
1664  const ValueDecl *D = getValueDecl(Exp);
1665  if (!D || !D->hasAttrs())
1666    return;
1667
1668  if (D->hasAttr<PtGuardedVarAttr>() && FSet.isEmpty(Analyzer->FactMan))
1669    Analyzer->Handler.handleNoMutexHeld("mutex", D, PtPOK, AK,
1670                                        Exp->getExprLoc());
1671
1672  for (auto const *I : D->specific_attrs<PtGuardedByAttr>())
1673    warnIfMutexNotHeld(D, Exp, AK, I->getArg(), PtPOK,
1674                       ClassifyDiagnostic(I), Exp->getExprLoc());
1675}
1676
1677/// \brief Process a function call, method call, constructor call,
1678/// or destructor call.  This involves looking at the attributes on the
1679/// corresponding function/method/constructor/destructor, issuing warnings,
1680/// and updating the locksets accordingly.
1681///
1682/// FIXME: For classes annotated with one of the guarded annotations, we need
1683/// to treat const method calls as reads and non-const method calls as writes,
1684/// and check that the appropriate locks are held. Non-const method calls with
1685/// the same signature as const method calls can be also treated as reads.
1686///
1687void BuildLockset::handleCall(Expr *Exp, const NamedDecl *D, VarDecl *VD) {
1688  SourceLocation Loc = Exp->getExprLoc();
1689  CapExprSet ExclusiveLocksToAdd, SharedLocksToAdd;
1690  CapExprSet ExclusiveLocksToRemove, SharedLocksToRemove, GenericLocksToRemove;
1691  CapExprSet ScopedExclusiveReqs, ScopedSharedReqs;
1692  StringRef CapDiagKind = "mutex";
1693
1694  // Figure out if we're calling the constructor of scoped lockable class
1695  bool isScopedVar = false;
1696  if (VD) {
1697    if (const CXXConstructorDecl *CD = dyn_cast<const CXXConstructorDecl>(D)) {
1698      const CXXRecordDecl* PD = CD->getParent();
1699      if (PD && PD->hasAttr<ScopedLockableAttr>())
1700        isScopedVar = true;
1701    }
1702  }
1703
1704  for(Attr *Atconst : D->attrs()) {
1705    Attr* At = const_cast<Attr*>(Atconst);
1706    switch (At->getKind()) {
1707      // When we encounter a lock function, we need to add the lock to our
1708      // lockset.
1709      case attr::AcquireCapability: {
1710        auto *A = cast<AcquireCapabilityAttr>(At);
1711        Analyzer->getMutexIDs(A->isShared() ? SharedLocksToAdd
1712                                            : ExclusiveLocksToAdd,
1713                              A, Exp, D, VD);
1714
1715        CapDiagKind = ClassifyDiagnostic(A);
1716        break;
1717      }
1718
1719      // An assert will add a lock to the lockset, but will not generate
1720      // a warning if it is already there, and will not generate a warning
1721      // if it is not removed.
1722      case attr::AssertExclusiveLock: {
1723        AssertExclusiveLockAttr *A = cast<AssertExclusiveLockAttr>(At);
1724
1725        CapExprSet AssertLocks;
1726        Analyzer->getMutexIDs(AssertLocks, A, Exp, D, VD);
1727        for (const auto &AssertLock : AssertLocks)
1728          Analyzer->addLock(FSet,
1729                            llvm::make_unique<LockableFactEntry>(
1730                                AssertLock, LK_Exclusive, Loc, false, true),
1731                            ClassifyDiagnostic(A));
1732        break;
1733      }
1734      case attr::AssertSharedLock: {
1735        AssertSharedLockAttr *A = cast<AssertSharedLockAttr>(At);
1736
1737        CapExprSet AssertLocks;
1738        Analyzer->getMutexIDs(AssertLocks, A, Exp, D, VD);
1739        for (const auto &AssertLock : AssertLocks)
1740          Analyzer->addLock(FSet, llvm::make_unique<LockableFactEntry>(
1741                                      AssertLock, LK_Shared, Loc, false, true),
1742                            ClassifyDiagnostic(A));
1743        break;
1744      }
1745
1746      // When we encounter an unlock function, we need to remove unlocked
1747      // mutexes from the lockset, and flag a warning if they are not there.
1748      case attr::ReleaseCapability: {
1749        auto *A = cast<ReleaseCapabilityAttr>(At);
1750        if (A->isGeneric())
1751          Analyzer->getMutexIDs(GenericLocksToRemove, A, Exp, D, VD);
1752        else if (A->isShared())
1753          Analyzer->getMutexIDs(SharedLocksToRemove, A, Exp, D, VD);
1754        else
1755          Analyzer->getMutexIDs(ExclusiveLocksToRemove, A, Exp, D, VD);
1756
1757        CapDiagKind = ClassifyDiagnostic(A);
1758        break;
1759      }
1760
1761      case attr::RequiresCapability: {
1762        RequiresCapabilityAttr *A = cast<RequiresCapabilityAttr>(At);
1763        for (auto *Arg : A->args()) {
1764          warnIfMutexNotHeld(D, Exp, A->isShared() ? AK_Read : AK_Written, Arg,
1765                             POK_FunctionCall, ClassifyDiagnostic(A),
1766                             Exp->getExprLoc());
1767          // use for adopting a lock
1768          if (isScopedVar) {
1769            Analyzer->getMutexIDs(A->isShared() ? ScopedSharedReqs
1770                                                : ScopedExclusiveReqs,
1771                                  A, Exp, D, VD);
1772          }
1773        }
1774        break;
1775      }
1776
1777      case attr::LocksExcluded: {
1778        LocksExcludedAttr *A = cast<LocksExcludedAttr>(At);
1779        for (auto *Arg : A->args())
1780          warnIfMutexHeld(D, Exp, Arg, ClassifyDiagnostic(A));
1781        break;
1782      }
1783
1784      // Ignore attributes unrelated to thread-safety
1785      default:
1786        break;
1787    }
1788  }
1789
1790  // Add locks.
1791  for (const auto &M : ExclusiveLocksToAdd)
1792    Analyzer->addLock(FSet, llvm::make_unique<LockableFactEntry>(
1793                                M, LK_Exclusive, Loc, isScopedVar),
1794                      CapDiagKind);
1795  for (const auto &M : SharedLocksToAdd)
1796    Analyzer->addLock(FSet, llvm::make_unique<LockableFactEntry>(
1797                                M, LK_Shared, Loc, isScopedVar),
1798                      CapDiagKind);
1799
1800  if (isScopedVar) {
1801    // Add the managing object as a dummy mutex, mapped to the underlying mutex.
1802    SourceLocation MLoc = VD->getLocation();
1803    DeclRefExpr DRE(VD, false, VD->getType(), VK_LValue, VD->getLocation());
1804    // FIXME: does this store a pointer to DRE?
1805    CapabilityExpr Scp = Analyzer->SxBuilder.translateAttrExpr(&DRE, nullptr);
1806
1807    std::copy(ScopedExclusiveReqs.begin(), ScopedExclusiveReqs.end(),
1808              std::back_inserter(ExclusiveLocksToAdd));
1809    std::copy(ScopedSharedReqs.begin(), ScopedSharedReqs.end(),
1810              std::back_inserter(SharedLocksToAdd));
1811    Analyzer->addLock(FSet,
1812                      llvm::make_unique<ScopedLockableFactEntry>(
1813                          Scp, MLoc, ExclusiveLocksToAdd, SharedLocksToAdd),
1814                      CapDiagKind);
1815  }
1816
1817  // Remove locks.
1818  // FIXME -- should only fully remove if the attribute refers to 'this'.
1819  bool Dtor = isa<CXXDestructorDecl>(D);
1820  for (const auto &M : ExclusiveLocksToRemove)
1821    Analyzer->removeLock(FSet, M, Loc, Dtor, LK_Exclusive, CapDiagKind);
1822  for (const auto &M : SharedLocksToRemove)
1823    Analyzer->removeLock(FSet, M, Loc, Dtor, LK_Shared, CapDiagKind);
1824  for (const auto &M : GenericLocksToRemove)
1825    Analyzer->removeLock(FSet, M, Loc, Dtor, LK_Generic, CapDiagKind);
1826}
1827
1828
1829/// \brief For unary operations which read and write a variable, we need to
1830/// check whether we hold any required mutexes. Reads are checked in
1831/// VisitCastExpr.
1832void BuildLockset::VisitUnaryOperator(UnaryOperator *UO) {
1833  switch (UO->getOpcode()) {
1834    case clang::UO_PostDec:
1835    case clang::UO_PostInc:
1836    case clang::UO_PreDec:
1837    case clang::UO_PreInc: {
1838      checkAccess(UO->getSubExpr(), AK_Written);
1839      break;
1840    }
1841    default:
1842      break;
1843  }
1844}
1845
1846/// For binary operations which assign to a variable (writes), we need to check
1847/// whether we hold any required mutexes.
1848/// FIXME: Deal with non-primitive types.
1849void BuildLockset::VisitBinaryOperator(BinaryOperator *BO) {
1850  if (!BO->isAssignmentOp())
1851    return;
1852
1853  // adjust the context
1854  LVarCtx = Analyzer->LocalVarMap.getNextContext(CtxIndex, BO, LVarCtx);
1855
1856  checkAccess(BO->getLHS(), AK_Written);
1857}
1858
1859
1860/// Whenever we do an LValue to Rvalue cast, we are reading a variable and
1861/// need to ensure we hold any required mutexes.
1862/// FIXME: Deal with non-primitive types.
1863void BuildLockset::VisitCastExpr(CastExpr *CE) {
1864  if (CE->getCastKind() != CK_LValueToRValue)
1865    return;
1866  checkAccess(CE->getSubExpr(), AK_Read);
1867}
1868
1869
1870void BuildLockset::VisitCallExpr(CallExpr *Exp) {
1871  bool ExamineArgs = true;
1872  bool OperatorFun = false;
1873
1874  if (CXXMemberCallExpr *CE = dyn_cast<CXXMemberCallExpr>(Exp)) {
1875    MemberExpr *ME = dyn_cast<MemberExpr>(CE->getCallee());
1876    // ME can be null when calling a method pointer
1877    CXXMethodDecl *MD = CE->getMethodDecl();
1878
1879    if (ME && MD) {
1880      if (ME->isArrow()) {
1881        if (MD->isConst()) {
1882          checkPtAccess(CE->getImplicitObjectArgument(), AK_Read);
1883        } else {  // FIXME -- should be AK_Written
1884          checkPtAccess(CE->getImplicitObjectArgument(), AK_Read);
1885        }
1886      } else {
1887        if (MD->isConst())
1888          checkAccess(CE->getImplicitObjectArgument(), AK_Read);
1889        else     // FIXME -- should be AK_Written
1890          checkAccess(CE->getImplicitObjectArgument(), AK_Read);
1891      }
1892    }
1893  } else if (CXXOperatorCallExpr *OE = dyn_cast<CXXOperatorCallExpr>(Exp)) {
1894    OperatorFun = true;
1895
1896    auto OEop = OE->getOperator();
1897    switch (OEop) {
1898      case OO_Equal: {
1899        ExamineArgs = false;
1900        const Expr *Target = OE->getArg(0);
1901        const Expr *Source = OE->getArg(1);
1902        checkAccess(Target, AK_Written);
1903        checkAccess(Source, AK_Read);
1904        break;
1905      }
1906      case OO_Star:
1907      case OO_Arrow:
1908      case OO_Subscript: {
1909        const Expr *Obj = OE->getArg(0);
1910        checkAccess(Obj, AK_Read);
1911        if (!(OEop == OO_Star && OE->getNumArgs() > 1)) {
1912          // Grrr.  operator* can be multiplication...
1913          checkPtAccess(Obj, AK_Read);
1914        }
1915        break;
1916      }
1917      default: {
1918        // TODO: get rid of this, and rely on pass-by-ref instead.
1919        const Expr *Obj = OE->getArg(0);
1920        checkAccess(Obj, AK_Read);
1921        break;
1922      }
1923    }
1924  }
1925
1926  if (ExamineArgs) {
1927    if (FunctionDecl *FD = Exp->getDirectCallee()) {
1928
1929      // NO_THREAD_SAFETY_ANALYSIS does double duty here.  Normally it
1930      // only turns off checking within the body of a function, but we also
1931      // use it to turn off checking in arguments to the function.  This
1932      // could result in some false negatives, but the alternative is to
1933      // create yet another attribute.
1934      //
1935      if (!FD->hasAttr<NoThreadSafetyAnalysisAttr>()) {
1936        unsigned Fn = FD->getNumParams();
1937        unsigned Cn = Exp->getNumArgs();
1938        unsigned Skip = 0;
1939
1940        unsigned i = 0;
1941        if (OperatorFun) {
1942          if (isa<CXXMethodDecl>(FD)) {
1943            // First arg in operator call is implicit self argument,
1944            // and doesn't appear in the FunctionDecl.
1945            Skip = 1;
1946            Cn--;
1947          } else {
1948            // Ignore the first argument of operators; it's been checked above.
1949            i = 1;
1950          }
1951        }
1952        // Ignore default arguments
1953        unsigned n = (Fn < Cn) ? Fn : Cn;
1954
1955        for (; i < n; ++i) {
1956          ParmVarDecl* Pvd = FD->getParamDecl(i);
1957          Expr* Arg = Exp->getArg(i+Skip);
1958          QualType Qt = Pvd->getType();
1959          if (Qt->isReferenceType())
1960            checkAccess(Arg, AK_Read, POK_PassByRef);
1961        }
1962      }
1963    }
1964  }
1965
1966  NamedDecl *D = dyn_cast_or_null<NamedDecl>(Exp->getCalleeDecl());
1967  if(!D || !D->hasAttrs())
1968    return;
1969  handleCall(Exp, D);
1970}
1971
1972void BuildLockset::VisitCXXConstructExpr(CXXConstructExpr *Exp) {
1973  const CXXConstructorDecl *D = Exp->getConstructor();
1974  if (D && D->isCopyConstructor()) {
1975    const Expr* Source = Exp->getArg(0);
1976    checkAccess(Source, AK_Read);
1977  }
1978  // FIXME -- only handles constructors in DeclStmt below.
1979}
1980
1981void BuildLockset::VisitDeclStmt(DeclStmt *S) {
1982  // adjust the context
1983  LVarCtx = Analyzer->LocalVarMap.getNextContext(CtxIndex, S, LVarCtx);
1984
1985  for (auto *D : S->getDeclGroup()) {
1986    if (VarDecl *VD = dyn_cast_or_null<VarDecl>(D)) {
1987      Expr *E = VD->getInit();
1988      // handle constructors that involve temporaries
1989      if (ExprWithCleanups *EWC = dyn_cast_or_null<ExprWithCleanups>(E))
1990        E = EWC->getSubExpr();
1991
1992      if (CXXConstructExpr *CE = dyn_cast_or_null<CXXConstructExpr>(E)) {
1993        NamedDecl *CtorD = dyn_cast_or_null<NamedDecl>(CE->getConstructor());
1994        if (!CtorD || !CtorD->hasAttrs())
1995          return;
1996        handleCall(CE, CtorD, VD);
1997      }
1998    }
1999  }
2000}
2001
2002
2003
2004/// \brief Compute the intersection of two locksets and issue warnings for any
2005/// locks in the symmetric difference.
2006///
2007/// This function is used at a merge point in the CFG when comparing the lockset
2008/// of each branch being merged. For example, given the following sequence:
2009/// A; if () then B; else C; D; we need to check that the lockset after B and C
2010/// are the same. In the event of a difference, we use the intersection of these
2011/// two locksets at the start of D.
2012///
2013/// \param FSet1 The first lockset.
2014/// \param FSet2 The second lockset.
2015/// \param JoinLoc The location of the join point for error reporting
2016/// \param LEK1 The error message to report if a mutex is missing from LSet1
2017/// \param LEK2 The error message to report if a mutex is missing from Lset2
2018void ThreadSafetyAnalyzer::intersectAndWarn(FactSet &FSet1,
2019                                            const FactSet &FSet2,
2020                                            SourceLocation JoinLoc,
2021                                            LockErrorKind LEK1,
2022                                            LockErrorKind LEK2,
2023                                            bool Modify) {
2024  FactSet FSet1Orig = FSet1;
2025
2026  // Find locks in FSet2 that conflict or are not in FSet1, and warn.
2027  for (const auto &Fact : FSet2) {
2028    const FactEntry *LDat1 = nullptr;
2029    const FactEntry *LDat2 = &FactMan[Fact];
2030    FactSet::iterator Iter1  = FSet1.findLockIter(FactMan, *LDat2);
2031    if (Iter1 != FSet1.end()) LDat1 = &FactMan[*Iter1];
2032
2033    if (LDat1) {
2034      if (LDat1->kind() != LDat2->kind()) {
2035        Handler.handleExclusiveAndShared("mutex", LDat2->toString(),
2036                                         LDat2->loc(), LDat1->loc());
2037        if (Modify && LDat1->kind() != LK_Exclusive) {
2038          // Take the exclusive lock, which is the one in FSet2.
2039          *Iter1 = Fact;
2040        }
2041      }
2042      else if (Modify && LDat1->asserted() && !LDat2->asserted()) {
2043        // The non-asserted lock in FSet2 is the one we want to track.
2044        *Iter1 = Fact;
2045      }
2046    } else {
2047      LDat2->handleRemovalFromIntersection(FSet2, FactMan, JoinLoc, LEK1,
2048                                           Handler);
2049    }
2050  }
2051
2052  // Find locks in FSet1 that are not in FSet2, and remove them.
2053  for (const auto &Fact : FSet1Orig) {
2054    const FactEntry *LDat1 = &FactMan[Fact];
2055    const FactEntry *LDat2 = FSet2.findLock(FactMan, *LDat1);
2056
2057    if (!LDat2) {
2058      LDat1->handleRemovalFromIntersection(FSet1Orig, FactMan, JoinLoc, LEK2,
2059                                           Handler);
2060      if (Modify)
2061        FSet1.removeLock(FactMan, *LDat1);
2062    }
2063  }
2064}
2065
2066
2067// Return true if block B never continues to its successors.
2068static bool neverReturns(const CFGBlock *B) {
2069  if (B->hasNoReturnElement())
2070    return true;
2071  if (B->empty())
2072    return false;
2073
2074  CFGElement Last = B->back();
2075  if (Optional<CFGStmt> S = Last.getAs<CFGStmt>()) {
2076    if (isa<CXXThrowExpr>(S->getStmt()))
2077      return true;
2078  }
2079  return false;
2080}
2081
2082
2083/// \brief Check a function's CFG for thread-safety violations.
2084///
2085/// We traverse the blocks in the CFG, compute the set of mutexes that are held
2086/// at the end of each block, and issue warnings for thread safety violations.
2087/// Each block in the CFG is traversed exactly once.
2088void ThreadSafetyAnalyzer::runAnalysis(AnalysisDeclContext &AC) {
2089  // TODO: this whole function needs be rewritten as a visitor for CFGWalker.
2090  // For now, we just use the walker to set things up.
2091  threadSafety::CFGWalker walker;
2092  if (!walker.init(AC))
2093    return;
2094
2095  // AC.dumpCFG(true);
2096  // threadSafety::printSCFG(walker);
2097
2098  CFG *CFGraph = walker.getGraph();
2099  const NamedDecl *D = walker.getDecl();
2100  const FunctionDecl *CurrentFunction = dyn_cast<FunctionDecl>(D);
2101  CurrentMethod = dyn_cast<CXXMethodDecl>(D);
2102
2103  if (D->hasAttr<NoThreadSafetyAnalysisAttr>())
2104    return;
2105
2106  // FIXME: Do something a bit more intelligent inside constructor and
2107  // destructor code.  Constructors and destructors must assume unique access
2108  // to 'this', so checks on member variable access is disabled, but we should
2109  // still enable checks on other objects.
2110  if (isa<CXXConstructorDecl>(D))
2111    return;  // Don't check inside constructors.
2112  if (isa<CXXDestructorDecl>(D))
2113    return;  // Don't check inside destructors.
2114
2115  Handler.enterFunction(CurrentFunction);
2116
2117  BlockInfo.resize(CFGraph->getNumBlockIDs(),
2118    CFGBlockInfo::getEmptyBlockInfo(LocalVarMap));
2119
2120  // We need to explore the CFG via a "topological" ordering.
2121  // That way, we will be guaranteed to have information about required
2122  // predecessor locksets when exploring a new block.
2123  const PostOrderCFGView *SortedGraph = walker.getSortedGraph();
2124  PostOrderCFGView::CFGBlockSet VisitedBlocks(CFGraph);
2125
2126  // Mark entry block as reachable
2127  BlockInfo[CFGraph->getEntry().getBlockID()].Reachable = true;
2128
2129  // Compute SSA names for local variables
2130  LocalVarMap.traverseCFG(CFGraph, SortedGraph, BlockInfo);
2131
2132  // Fill in source locations for all CFGBlocks.
2133  findBlockLocations(CFGraph, SortedGraph, BlockInfo);
2134
2135  CapExprSet ExclusiveLocksAcquired;
2136  CapExprSet SharedLocksAcquired;
2137  CapExprSet LocksReleased;
2138
2139  // Add locks from exclusive_locks_required and shared_locks_required
2140  // to initial lockset. Also turn off checking for lock and unlock functions.
2141  // FIXME: is there a more intelligent way to check lock/unlock functions?
2142  if (!SortedGraph->empty() && D->hasAttrs()) {
2143    const CFGBlock *FirstBlock = *SortedGraph->begin();
2144    FactSet &InitialLockset = BlockInfo[FirstBlock->getBlockID()].EntrySet;
2145
2146    CapExprSet ExclusiveLocksToAdd;
2147    CapExprSet SharedLocksToAdd;
2148    StringRef CapDiagKind = "mutex";
2149
2150    SourceLocation Loc = D->getLocation();
2151    for (const auto *Attr : D->attrs()) {
2152      Loc = Attr->getLocation();
2153      if (const auto *A = dyn_cast<RequiresCapabilityAttr>(Attr)) {
2154        getMutexIDs(A->isShared() ? SharedLocksToAdd : ExclusiveLocksToAdd, A,
2155                    nullptr, D);
2156        CapDiagKind = ClassifyDiagnostic(A);
2157      } else if (const auto *A = dyn_cast<ReleaseCapabilityAttr>(Attr)) {
2158        // UNLOCK_FUNCTION() is used to hide the underlying lock implementation.
2159        // We must ignore such methods.
2160        if (A->args_size() == 0)
2161          return;
2162        // FIXME -- deal with exclusive vs. shared unlock functions?
2163        getMutexIDs(ExclusiveLocksToAdd, A, nullptr, D);
2164        getMutexIDs(LocksReleased, A, nullptr, D);
2165        CapDiagKind = ClassifyDiagnostic(A);
2166      } else if (const auto *A = dyn_cast<AcquireCapabilityAttr>(Attr)) {
2167        if (A->args_size() == 0)
2168          return;
2169        getMutexIDs(A->isShared() ? SharedLocksAcquired
2170                                  : ExclusiveLocksAcquired,
2171                    A, nullptr, D);
2172        CapDiagKind = ClassifyDiagnostic(A);
2173      } else if (isa<ExclusiveTrylockFunctionAttr>(Attr)) {
2174        // Don't try to check trylock functions for now
2175        return;
2176      } else if (isa<SharedTrylockFunctionAttr>(Attr)) {
2177        // Don't try to check trylock functions for now
2178        return;
2179      }
2180    }
2181
2182    // FIXME -- Loc can be wrong here.
2183    for (const auto &Mu : ExclusiveLocksToAdd) {
2184      auto Entry = llvm::make_unique<LockableFactEntry>(Mu, LK_Exclusive, Loc);
2185      Entry->setDeclared(true);
2186      addLock(InitialLockset, std::move(Entry), CapDiagKind, true);
2187    }
2188    for (const auto &Mu : SharedLocksToAdd) {
2189      auto Entry = llvm::make_unique<LockableFactEntry>(Mu, LK_Shared, Loc);
2190      Entry->setDeclared(true);
2191      addLock(InitialLockset, std::move(Entry), CapDiagKind, true);
2192    }
2193  }
2194
2195  for (const auto *CurrBlock : *SortedGraph) {
2196    int CurrBlockID = CurrBlock->getBlockID();
2197    CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlockID];
2198
2199    // Use the default initial lockset in case there are no predecessors.
2200    VisitedBlocks.insert(CurrBlock);
2201
2202    // Iterate through the predecessor blocks and warn if the lockset for all
2203    // predecessors is not the same. We take the entry lockset of the current
2204    // block to be the intersection of all previous locksets.
2205    // FIXME: By keeping the intersection, we may output more errors in future
2206    // for a lock which is not in the intersection, but was in the union. We
2207    // may want to also keep the union in future. As an example, let's say
2208    // the intersection contains Mutex L, and the union contains L and M.
2209    // Later we unlock M. At this point, we would output an error because we
2210    // never locked M; although the real error is probably that we forgot to
2211    // lock M on all code paths. Conversely, let's say that later we lock M.
2212    // In this case, we should compare against the intersection instead of the
2213    // union because the real error is probably that we forgot to unlock M on
2214    // all code paths.
2215    bool LocksetInitialized = false;
2216    SmallVector<CFGBlock *, 8> SpecialBlocks;
2217    for (CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
2218         PE  = CurrBlock->pred_end(); PI != PE; ++PI) {
2219
2220      // if *PI -> CurrBlock is a back edge
2221      if (*PI == nullptr || !VisitedBlocks.alreadySet(*PI))
2222        continue;
2223
2224      int PrevBlockID = (*PI)->getBlockID();
2225      CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
2226
2227      // Ignore edges from blocks that can't return.
2228      if (neverReturns(*PI) || !PrevBlockInfo->Reachable)
2229        continue;
2230
2231      // Okay, we can reach this block from the entry.
2232      CurrBlockInfo->Reachable = true;
2233
2234      // If the previous block ended in a 'continue' or 'break' statement, then
2235      // a difference in locksets is probably due to a bug in that block, rather
2236      // than in some other predecessor. In that case, keep the other
2237      // predecessor's lockset.
2238      if (const Stmt *Terminator = (*PI)->getTerminator()) {
2239        if (isa<ContinueStmt>(Terminator) || isa<BreakStmt>(Terminator)) {
2240          SpecialBlocks.push_back(*PI);
2241          continue;
2242        }
2243      }
2244
2245      FactSet PrevLockset;
2246      getEdgeLockset(PrevLockset, PrevBlockInfo->ExitSet, *PI, CurrBlock);
2247
2248      if (!LocksetInitialized) {
2249        CurrBlockInfo->EntrySet = PrevLockset;
2250        LocksetInitialized = true;
2251      } else {
2252        intersectAndWarn(CurrBlockInfo->EntrySet, PrevLockset,
2253                         CurrBlockInfo->EntryLoc,
2254                         LEK_LockedSomePredecessors);
2255      }
2256    }
2257
2258    // Skip rest of block if it's not reachable.
2259    if (!CurrBlockInfo->Reachable)
2260      continue;
2261
2262    // Process continue and break blocks. Assume that the lockset for the
2263    // resulting block is unaffected by any discrepancies in them.
2264    for (const auto *PrevBlock : SpecialBlocks) {
2265      int PrevBlockID = PrevBlock->getBlockID();
2266      CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
2267
2268      if (!LocksetInitialized) {
2269        CurrBlockInfo->EntrySet = PrevBlockInfo->ExitSet;
2270        LocksetInitialized = true;
2271      } else {
2272        // Determine whether this edge is a loop terminator for diagnostic
2273        // purposes. FIXME: A 'break' statement might be a loop terminator, but
2274        // it might also be part of a switch. Also, a subsequent destructor
2275        // might add to the lockset, in which case the real issue might be a
2276        // double lock on the other path.
2277        const Stmt *Terminator = PrevBlock->getTerminator();
2278        bool IsLoop = Terminator && isa<ContinueStmt>(Terminator);
2279
2280        FactSet PrevLockset;
2281        getEdgeLockset(PrevLockset, PrevBlockInfo->ExitSet,
2282                       PrevBlock, CurrBlock);
2283
2284        // Do not update EntrySet.
2285        intersectAndWarn(CurrBlockInfo->EntrySet, PrevLockset,
2286                         PrevBlockInfo->ExitLoc,
2287                         IsLoop ? LEK_LockedSomeLoopIterations
2288                                : LEK_LockedSomePredecessors,
2289                         false);
2290      }
2291    }
2292
2293    BuildLockset LocksetBuilder(this, *CurrBlockInfo);
2294
2295    // Visit all the statements in the basic block.
2296    for (CFGBlock::const_iterator BI = CurrBlock->begin(),
2297         BE = CurrBlock->end(); BI != BE; ++BI) {
2298      switch (BI->getKind()) {
2299        case CFGElement::Statement: {
2300          CFGStmt CS = BI->castAs<CFGStmt>();
2301          LocksetBuilder.Visit(const_cast<Stmt*>(CS.getStmt()));
2302          break;
2303        }
2304        // Ignore BaseDtor, MemberDtor, and TemporaryDtor for now.
2305        case CFGElement::AutomaticObjectDtor: {
2306          CFGAutomaticObjDtor AD = BI->castAs<CFGAutomaticObjDtor>();
2307          CXXDestructorDecl *DD = const_cast<CXXDestructorDecl *>(
2308              AD.getDestructorDecl(AC.getASTContext()));
2309          if (!DD->hasAttrs())
2310            break;
2311
2312          // Create a dummy expression,
2313          VarDecl *VD = const_cast<VarDecl*>(AD.getVarDecl());
2314          DeclRefExpr DRE(VD, false, VD->getType().getNonReferenceType(),
2315                          VK_LValue, AD.getTriggerStmt()->getLocEnd());
2316          LocksetBuilder.handleCall(&DRE, DD);
2317          break;
2318        }
2319        default:
2320          break;
2321      }
2322    }
2323    CurrBlockInfo->ExitSet = LocksetBuilder.FSet;
2324
2325    // For every back edge from CurrBlock (the end of the loop) to another block
2326    // (FirstLoopBlock) we need to check that the Lockset of Block is equal to
2327    // the one held at the beginning of FirstLoopBlock. We can look up the
2328    // Lockset held at the beginning of FirstLoopBlock in the EntryLockSets map.
2329    for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
2330         SE  = CurrBlock->succ_end(); SI != SE; ++SI) {
2331
2332      // if CurrBlock -> *SI is *not* a back edge
2333      if (*SI == nullptr || !VisitedBlocks.alreadySet(*SI))
2334        continue;
2335
2336      CFGBlock *FirstLoopBlock = *SI;
2337      CFGBlockInfo *PreLoop = &BlockInfo[FirstLoopBlock->getBlockID()];
2338      CFGBlockInfo *LoopEnd = &BlockInfo[CurrBlockID];
2339      intersectAndWarn(LoopEnd->ExitSet, PreLoop->EntrySet,
2340                       PreLoop->EntryLoc,
2341                       LEK_LockedSomeLoopIterations,
2342                       false);
2343    }
2344  }
2345
2346  CFGBlockInfo *Initial = &BlockInfo[CFGraph->getEntry().getBlockID()];
2347  CFGBlockInfo *Final   = &BlockInfo[CFGraph->getExit().getBlockID()];
2348
2349  // Skip the final check if the exit block is unreachable.
2350  if (!Final->Reachable)
2351    return;
2352
2353  // By default, we expect all locks held on entry to be held on exit.
2354  FactSet ExpectedExitSet = Initial->EntrySet;
2355
2356  // Adjust the expected exit set by adding or removing locks, as declared
2357  // by *-LOCK_FUNCTION and UNLOCK_FUNCTION.  The intersect below will then
2358  // issue the appropriate warning.
2359  // FIXME: the location here is not quite right.
2360  for (const auto &Lock : ExclusiveLocksAcquired)
2361    ExpectedExitSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
2362                                         Lock, LK_Exclusive, D->getLocation()));
2363  for (const auto &Lock : SharedLocksAcquired)
2364    ExpectedExitSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
2365                                         Lock, LK_Shared, D->getLocation()));
2366  for (const auto &Lock : LocksReleased)
2367    ExpectedExitSet.removeLock(FactMan, Lock);
2368
2369  // FIXME: Should we call this function for all blocks which exit the function?
2370  intersectAndWarn(ExpectedExitSet, Final->ExitSet,
2371                   Final->ExitLoc,
2372                   LEK_LockedAtEndOfFunction,
2373                   LEK_NotLockedAtEndOfFunction,
2374                   false);
2375
2376  Handler.leaveFunction(CurrentFunction);
2377}
2378
2379
2380/// \brief Check a function's CFG for thread-safety violations.
2381///
2382/// We traverse the blocks in the CFG, compute the set of mutexes that are held
2383/// at the end of each block, and issue warnings for thread safety violations.
2384/// Each block in the CFG is traversed exactly once.
2385void threadSafety::runThreadSafetyAnalysis(AnalysisDeclContext &AC,
2386                                           ThreadSafetyHandler &Handler,
2387                                           BeforeSet **BSet) {
2388  if (!*BSet)
2389    *BSet = new BeforeSet;
2390  ThreadSafetyAnalyzer Analyzer(Handler, *BSet);
2391  Analyzer.runAnalysis(AC);
2392}
2393
2394void threadSafety::threadSafetyCleanup(BeforeSet *Cache) { delete Cache; }
2395
2396/// \brief Helper function that returns a LockKind required for the given level
2397/// of access.
2398LockKind threadSafety::getLockKindFromAccessKind(AccessKind AK) {
2399  switch (AK) {
2400    case AK_Read :
2401      return LK_Shared;
2402    case AK_Written :
2403      return LK_Exclusive;
2404  }
2405  llvm_unreachable("Unknown AccessKind");
2406}
2407