1 //===- ThreadSafety.cpp ----------------------------------------*- C++ --*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // A intra-procedural analysis for thread safety (e.g. deadlocks and race
11 // conditions), based off of an annotation system.
13 // See http://clang.llvm.org/docs/LanguageExtensions.html#threadsafety for more
16 //===----------------------------------------------------------------------===//
18 #include "clang/Analysis/Analyses/ThreadSafety.h"
19 #include "clang/Analysis/Analyses/PostOrderCFGView.h"
20 #include "clang/Analysis/AnalysisContext.h"
21 #include "clang/Analysis/CFG.h"
22 #include "clang/Analysis/CFGStmtMap.h"
23 #include "clang/AST/DeclCXX.h"
24 #include "clang/AST/ExprCXX.h"
25 #include "clang/AST/StmtCXX.h"
26 #include "clang/AST/StmtVisitor.h"
27 #include "clang/Basic/SourceManager.h"
28 #include "clang/Basic/SourceLocation.h"
29 #include "llvm/ADT/BitVector.h"
30 #include "llvm/ADT/FoldingSet.h"
31 #include "llvm/ADT/ImmutableMap.h"
32 #include "llvm/ADT/PostOrderIterator.h"
33 #include "llvm/ADT/SmallVector.h"
34 #include "llvm/ADT/StringRef.h"
35 #include "llvm/Support/raw_ostream.h"
40 using namespace clang;
41 using namespace thread_safety;
43 // Key method definition
44 ThreadSafetyHandler::~ThreadSafetyHandler() {}
48 /// \brief A MutexID object uniquely identifies a particular mutex, and
49 /// is built from an Expr* (i.e. calling a lock function).
51 /// Thread-safety analysis works by comparing lock expressions. Within the
52 /// body of a function, an expression such as "x->foo->bar.mu" will resolve to
53 /// a particular mutex object at run-time. Subsequent occurrences of the same
54 /// expression (where "same" means syntactic equality) will refer to the same
55 /// run-time object if three conditions hold:
56 /// (1) Local variables in the expression, such as "x" have not changed.
57 /// (2) Values on the heap that affect the expression have not changed.
58 /// (3) The expression involves only pure function calls.
60 /// The current implementation assumes, but does not verify, that multiple uses
61 /// of the same lock expression satisfies these criteria.
63 /// Clang introduces an additional wrinkle, which is that it is difficult to
64 /// derive canonical expressions, or compare expressions directly for equality.
65 /// Thus, we identify a mutex not by an Expr, but by the list of named
66 /// declarations that are referenced by the Expr. In other words,
67 /// x->foo->bar.mu will be a four element vector with the Decls for
68 /// mu, bar, and foo, and x. The vector will uniquely identify the expression
69 /// for all practical purposes. Null is used to denote 'this'.
71 /// Note we will need to perform substitution on "this" and function parameter
72 /// names when constructing a lock expression.
75 /// class C { Mutex Mu; void lock() EXCLUSIVE_LOCK_FUNCTION(this->Mu); };
76 /// void myFunc(C *X) { ... X->lock() ... }
77 /// The original expression for the mutex acquired by myFunc is "this->Mu", but
78 /// "X" is substituted for "this" so we get X->Mu();
80 /// For another example:
81 /// foo(MyList *L) EXCLUSIVE_LOCKS_REQUIRED(L->Mu) { ... }
83 /// foo(MyL); // requires lock MyL->Mu to be held
85 SmallVector<NamedDecl*, 2> DeclSeq;
87 /// Build a Decl sequence representing the lock from the given expression.
88 /// Recursive function that terminates on DeclRefExpr.
89 /// Note: this function merely creates a MutexID; it does not check to
90 /// ensure that the original expression is a valid mutex expression.
91 void buildMutexID(Expr *Exp, const NamedDecl *D, Expr *Parent,
92 unsigned NumArgs, Expr **FunArgs) {
98 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Exp)) {
99 NamedDecl *ND = cast<NamedDecl>(DRE->getDecl()->getCanonicalDecl());
100 ParmVarDecl *PV = dyn_cast_or_null<ParmVarDecl>(ND);
103 cast<FunctionDecl>(PV->getDeclContext())->getCanonicalDecl();
104 unsigned i = PV->getFunctionScopeIndex();
106 if (FunArgs && FD == D->getCanonicalDecl()) {
107 // Substitute call arguments for references to function parameters
109 buildMutexID(FunArgs[i], D, 0, 0, 0);
112 // Map the param back to the param of the original function declaration.
113 DeclSeq.push_back(FD->getParamDecl(i));
116 // Not a function parameter -- just store the reference.
117 DeclSeq.push_back(ND);
118 } else if (MemberExpr *ME = dyn_cast<MemberExpr>(Exp)) {
119 NamedDecl *ND = ME->getMemberDecl();
120 DeclSeq.push_back(ND);
121 buildMutexID(ME->getBase(), D, Parent, NumArgs, FunArgs);
122 } else if (isa<CXXThisExpr>(Exp)) {
124 buildMutexID(Parent, D, 0, 0, 0);
126 DeclSeq.push_back(0); // Use 0 to represent 'this'.
127 return; // mutexID is still valid in this case
129 } else if (CXXMemberCallExpr *CMCE = dyn_cast<CXXMemberCallExpr>(Exp)) {
130 DeclSeq.push_back(CMCE->getMethodDecl()->getCanonicalDecl());
131 buildMutexID(CMCE->getImplicitObjectArgument(),
132 D, Parent, NumArgs, FunArgs);
133 unsigned NumCallArgs = CMCE->getNumArgs();
134 Expr** CallArgs = CMCE->getArgs();
135 for (unsigned i = 0; i < NumCallArgs; ++i) {
136 buildMutexID(CallArgs[i], D, Parent, NumArgs, FunArgs);
138 } else if (CallExpr *CE = dyn_cast<CallExpr>(Exp)) {
139 buildMutexID(CE->getCallee(), D, Parent, NumArgs, FunArgs);
140 unsigned NumCallArgs = CE->getNumArgs();
141 Expr** CallArgs = CE->getArgs();
142 for (unsigned i = 0; i < NumCallArgs; ++i) {
143 buildMutexID(CallArgs[i], D, Parent, NumArgs, FunArgs);
145 } else if (BinaryOperator *BOE = dyn_cast<BinaryOperator>(Exp)) {
146 buildMutexID(BOE->getLHS(), D, Parent, NumArgs, FunArgs);
147 buildMutexID(BOE->getRHS(), D, Parent, NumArgs, FunArgs);
148 } else if (UnaryOperator *UOE = dyn_cast<UnaryOperator>(Exp)) {
149 buildMutexID(UOE->getSubExpr(), D, Parent, NumArgs, FunArgs);
150 } else if (ArraySubscriptExpr *ASE = dyn_cast<ArraySubscriptExpr>(Exp)) {
151 buildMutexID(ASE->getBase(), D, Parent, NumArgs, FunArgs);
152 buildMutexID(ASE->getIdx(), D, Parent, NumArgs, FunArgs);
153 } else if (AbstractConditionalOperator *CE =
154 dyn_cast<AbstractConditionalOperator>(Exp)) {
155 buildMutexID(CE->getCond(), D, Parent, NumArgs, FunArgs);
156 buildMutexID(CE->getTrueExpr(), D, Parent, NumArgs, FunArgs);
157 buildMutexID(CE->getFalseExpr(), D, Parent, NumArgs, FunArgs);
158 } else if (ChooseExpr *CE = dyn_cast<ChooseExpr>(Exp)) {
159 buildMutexID(CE->getCond(), D, Parent, NumArgs, FunArgs);
160 buildMutexID(CE->getLHS(), D, Parent, NumArgs, FunArgs);
161 buildMutexID(CE->getRHS(), D, Parent, NumArgs, FunArgs);
162 } else if (CastExpr *CE = dyn_cast<CastExpr>(Exp)) {
163 buildMutexID(CE->getSubExpr(), D, Parent, NumArgs, FunArgs);
164 } else if (ParenExpr *PE = dyn_cast<ParenExpr>(Exp)) {
165 buildMutexID(PE->getSubExpr(), D, Parent, NumArgs, FunArgs);
166 } else if (isa<CharacterLiteral>(Exp) ||
167 isa<CXXNullPtrLiteralExpr>(Exp) ||
168 isa<GNUNullExpr>(Exp) ||
169 isa<CXXBoolLiteralExpr>(Exp) ||
170 isa<FloatingLiteral>(Exp) ||
171 isa<ImaginaryLiteral>(Exp) ||
172 isa<IntegerLiteral>(Exp) ||
173 isa<StringLiteral>(Exp) ||
174 isa<ObjCStringLiteral>(Exp)) {
175 return; // FIXME: Ignore literals for now
177 // Ignore. FIXME: mark as invalid expression?
181 /// \brief Construct a MutexID from an expression.
182 /// \param MutexExp The original mutex expression within an attribute
183 /// \param DeclExp An expression involving the Decl on which the attribute
185 /// \param D The declaration to which the lock/unlock attribute is attached.
186 void buildMutexIDFromExp(Expr *MutexExp, Expr *DeclExp, const NamedDecl *D) {
188 unsigned NumArgs = 0;
191 // If we are processing a raw attribute expression, with no substitutions.
193 buildMutexID(MutexExp, D, 0, 0, 0);
197 // Examine DeclExp to find Parent and FunArgs, which are used to substitute
198 // for formal parameters when we call buildMutexID later.
199 if (MemberExpr *ME = dyn_cast<MemberExpr>(DeclExp)) {
200 Parent = ME->getBase();
201 } else if (CXXMemberCallExpr *CE = dyn_cast<CXXMemberCallExpr>(DeclExp)) {
202 Parent = CE->getImplicitObjectArgument();
203 NumArgs = CE->getNumArgs();
204 FunArgs = CE->getArgs();
205 } else if (CallExpr *CE = dyn_cast<CallExpr>(DeclExp)) {
206 NumArgs = CE->getNumArgs();
207 FunArgs = CE->getArgs();
208 } else if (CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(DeclExp)) {
209 Parent = 0; // FIXME -- get the parent from DeclStmt
210 NumArgs = CE->getNumArgs();
211 FunArgs = CE->getArgs();
212 } else if (D && isa<CXXDestructorDecl>(D)) {
213 // There's no such thing as a "destructor call" in the AST.
217 // If the attribute has no arguments, then assume the argument is "this".
219 buildMutexID(Parent, D, 0, 0, 0);
223 buildMutexID(MutexExp, D, Parent, NumArgs, FunArgs);
227 explicit MutexID(clang::Decl::EmptyShell e) {
231 /// \param MutexExp The original mutex expression within an attribute
232 /// \param DeclExp An expression involving the Decl on which the attribute
234 /// \param D The declaration to which the lock/unlock attribute is attached.
235 /// Caller must check isValid() after construction.
236 MutexID(Expr* MutexExp, Expr *DeclExp, const NamedDecl* D) {
237 buildMutexIDFromExp(MutexExp, DeclExp, D);
240 /// Return true if this is a valid decl sequence.
241 /// Caller must call this by hand after construction to handle errors.
242 bool isValid() const {
243 return !DeclSeq.empty();
246 /// Issue a warning about an invalid lock expression
247 static void warnInvalidLock(ThreadSafetyHandler &Handler, Expr* MutexExp,
248 Expr *DeclExp, const NamedDecl* D) {
251 Loc = DeclExp->getExprLoc();
253 // FIXME: add a note about the attribute location in MutexExp or D
255 Handler.handleInvalidLockExp(Loc);
258 bool operator==(const MutexID &other) const {
259 return DeclSeq == other.DeclSeq;
262 bool operator!=(const MutexID &other) const {
263 return !(*this == other);
266 // SmallVector overloads Operator< to do lexicographic ordering. Note that
267 // we use pointer equality (and <) to compare NamedDecls. This means the order
268 // of MutexIDs in a lockset is nondeterministic. In order to output
269 // diagnostics in a deterministic ordering, we must order all diagnostics to
270 // output by SourceLocation when iterating through this lockset.
271 bool operator<(const MutexID &other) const {
272 return DeclSeq < other.DeclSeq;
275 /// \brief Returns the name of the first Decl in the list for a given MutexID;
276 /// e.g. the lock expression foo.bar() has name "bar".
277 /// The caret will point unambiguously to the lock expression, so using this
278 /// name in diagnostics is a way to get simple, and consistent, mutex names.
279 /// We do not want to output the entire expression text for security reasons.
280 std::string getName() const {
282 if (!DeclSeq.front())
283 return "this"; // Use 0 to represent 'this'.
284 return DeclSeq.front()->getNameAsString();
287 void Profile(llvm::FoldingSetNodeID &ID) const {
288 for (SmallVectorImpl<NamedDecl*>::const_iterator I = DeclSeq.begin(),
289 E = DeclSeq.end(); I != E; ++I) {
296 /// \brief This is a helper class that stores info about the most recent
297 /// accquire of a Lock.
299 /// The main body of the analysis maps MutexIDs to LockDatas.
301 SourceLocation AcquireLoc;
303 /// \brief LKind stores whether a lock is held shared or exclusively.
304 /// Note that this analysis does not currently support either re-entrant
305 /// locking or lock "upgrading" and "downgrading" between exclusive and
308 /// FIXME: add support for re-entrant locking and lock up/downgrading
310 MutexID UnderlyingMutex; // for ScopedLockable objects
312 LockData(SourceLocation AcquireLoc, LockKind LKind)
313 : AcquireLoc(AcquireLoc), LKind(LKind), UnderlyingMutex(Decl::EmptyShell())
316 LockData(SourceLocation AcquireLoc, LockKind LKind, const MutexID &Mu)
317 : AcquireLoc(AcquireLoc), LKind(LKind), UnderlyingMutex(Mu) {}
319 bool operator==(const LockData &other) const {
320 return AcquireLoc == other.AcquireLoc && LKind == other.LKind;
323 bool operator!=(const LockData &other) const {
324 return !(*this == other);
327 void Profile(llvm::FoldingSetNodeID &ID) const {
328 ID.AddInteger(AcquireLoc.getRawEncoding());
329 ID.AddInteger(LKind);
334 /// A Lockset maps each MutexID (defined above) to information about how it has
336 typedef llvm::ImmutableMap<MutexID, LockData> Lockset;
337 typedef llvm::ImmutableMap<NamedDecl*, unsigned> LocalVarContext;
339 class LocalVariableMap;
341 /// A side (entry or exit) of a CFG node.
342 enum CFGBlockSide { CBS_Entry, CBS_Exit };
344 /// CFGBlockInfo is a struct which contains all the information that is
345 /// maintained for each block in the CFG. See LocalVariableMap for more
346 /// information about the contexts.
347 struct CFGBlockInfo {
348 Lockset EntrySet; // Lockset held at entry to block
349 Lockset ExitSet; // Lockset held at exit from block
350 LocalVarContext EntryContext; // Context held at entry to block
351 LocalVarContext ExitContext; // Context held at exit from block
352 SourceLocation EntryLoc; // Location of first statement in block
353 SourceLocation ExitLoc; // Location of last statement in block.
354 unsigned EntryIndex; // Used to replay contexts later
356 const Lockset &getSet(CFGBlockSide Side) const {
357 return Side == CBS_Entry ? EntrySet : ExitSet;
359 SourceLocation getLocation(CFGBlockSide Side) const {
360 return Side == CBS_Entry ? EntryLoc : ExitLoc;
364 CFGBlockInfo(Lockset EmptySet, LocalVarContext EmptyCtx)
365 : EntrySet(EmptySet), ExitSet(EmptySet),
366 EntryContext(EmptyCtx), ExitContext(EmptyCtx)
370 static CFGBlockInfo getEmptyBlockInfo(Lockset::Factory &F,
371 LocalVariableMap &M);
376 // A LocalVariableMap maintains a map from local variables to their currently
377 // valid definitions. It provides SSA-like functionality when traversing the
378 // CFG. Like SSA, each definition or assignment to a variable is assigned a
379 // unique name (an integer), which acts as the SSA name for that definition.
380 // The total set of names is shared among all CFG basic blocks.
381 // Unlike SSA, we do not rewrite expressions to replace local variables declrefs
382 // with their SSA-names. Instead, we compute a Context for each point in the
383 // code, which maps local variables to the appropriate SSA-name. This map
384 // changes with each assignment.
386 // The map is computed in a single pass over the CFG. Subsequent analyses can
387 // then query the map to find the appropriate Context for a statement, and use
388 // that Context to look up the definitions of variables.
389 class LocalVariableMap {
391 typedef LocalVarContext Context;
393 /// A VarDefinition consists of an expression, representing the value of the
394 /// variable, along with the context in which that expression should be
395 /// interpreted. A reference VarDefinition does not itself contain this
396 /// information, but instead contains a pointer to a previous VarDefinition.
397 struct VarDefinition {
399 friend class LocalVariableMap;
401 NamedDecl *Dec; // The original declaration for this variable.
402 Expr *Exp; // The expression for this variable, OR
403 unsigned Ref; // Reference to another VarDefinition
404 Context Ctx; // The map with which Exp should be interpreted.
406 bool isReference() { return !Exp; }
409 // Create ordinary variable definition
410 VarDefinition(NamedDecl *D, Expr *E, Context C)
411 : Dec(D), Exp(E), Ref(0), Ctx(C)
414 // Create reference to previous definition
415 VarDefinition(NamedDecl *D, unsigned R, Context C)
416 : Dec(D), Exp(0), Ref(R), Ctx(C)
421 Context::Factory ContextFactory;
422 std::vector<VarDefinition> VarDefinitions;
423 std::vector<unsigned> CtxIndices;
424 std::vector<std::pair<Stmt*, Context> > SavedContexts;
428 // index 0 is a placeholder for undefined variables (aka phi-nodes).
429 VarDefinitions.push_back(VarDefinition(0, 0u, getEmptyContext()));
432 /// Look up a definition, within the given context.
433 const VarDefinition* lookup(NamedDecl *D, Context Ctx) {
434 const unsigned *i = Ctx.lookup(D);
437 assert(*i < VarDefinitions.size());
438 return &VarDefinitions[*i];
441 /// Look up the definition for D within the given context. Returns
442 /// NULL if the expression is not statically known. If successful, also
443 /// modifies Ctx to hold the context of the return Expr.
444 Expr* lookupExpr(NamedDecl *D, Context &Ctx) {
445 const unsigned *P = Ctx.lookup(D);
451 if (VarDefinitions[i].Exp) {
452 Ctx = VarDefinitions[i].Ctx;
453 return VarDefinitions[i].Exp;
455 i = VarDefinitions[i].Ref;
460 Context getEmptyContext() { return ContextFactory.getEmptyMap(); }
462 /// Return the next context after processing S. This function is used by
463 /// clients of the class to get the appropriate context when traversing the
464 /// CFG. It must be called for every assignment or DeclStmt.
465 Context getNextContext(unsigned &CtxIndex, Stmt *S, Context C) {
466 if (SavedContexts[CtxIndex+1].first == S) {
468 Context Result = SavedContexts[CtxIndex].second;
474 void dumpVarDefinitionName(unsigned i) {
476 llvm::errs() << "Undefined";
479 NamedDecl *Dec = VarDefinitions[i].Dec;
481 llvm::errs() << "<<NULL>>";
484 Dec->printName(llvm::errs());
485 llvm::errs() << "." << i << " " << ((void*) Dec);
488 /// Dumps an ASCII representation of the variable map to llvm::errs()
490 for (unsigned i = 1, e = VarDefinitions.size(); i < e; ++i) {
491 Expr *Exp = VarDefinitions[i].Exp;
492 unsigned Ref = VarDefinitions[i].Ref;
494 dumpVarDefinitionName(i);
495 llvm::errs() << " = ";
496 if (Exp) Exp->dump();
498 dumpVarDefinitionName(Ref);
499 llvm::errs() << "\n";
504 /// Dumps an ASCII representation of a Context to llvm::errs()
505 void dumpContext(Context C) {
506 for (Context::iterator I = C.begin(), E = C.end(); I != E; ++I) {
507 NamedDecl *D = I.getKey();
508 D->printName(llvm::errs());
509 const unsigned *i = C.lookup(D);
510 llvm::errs() << " -> ";
511 dumpVarDefinitionName(*i);
512 llvm::errs() << "\n";
516 /// Builds the variable map.
517 void traverseCFG(CFG *CFGraph, PostOrderCFGView *SortedGraph,
518 std::vector<CFGBlockInfo> &BlockInfo);
521 // Get the current context index
522 unsigned getContextIndex() { return SavedContexts.size()-1; }
524 // Save the current context for later replay
525 void saveContext(Stmt *S, Context C) {
526 SavedContexts.push_back(std::make_pair(S,C));
529 // Adds a new definition to the given context, and returns a new context.
530 // This method should be called when declaring a new variable.
531 Context addDefinition(NamedDecl *D, Expr *Exp, Context Ctx) {
532 assert(!Ctx.contains(D));
533 unsigned newID = VarDefinitions.size();
534 Context NewCtx = ContextFactory.add(Ctx, D, newID);
535 VarDefinitions.push_back(VarDefinition(D, Exp, Ctx));
539 // Add a new reference to an existing definition.
540 Context addReference(NamedDecl *D, unsigned i, Context Ctx) {
541 unsigned newID = VarDefinitions.size();
542 Context NewCtx = ContextFactory.add(Ctx, D, newID);
543 VarDefinitions.push_back(VarDefinition(D, i, Ctx));
547 // Updates a definition only if that definition is already in the map.
548 // This method should be called when assigning to an existing variable.
549 Context updateDefinition(NamedDecl *D, Expr *Exp, Context Ctx) {
550 if (Ctx.contains(D)) {
551 unsigned newID = VarDefinitions.size();
552 Context NewCtx = ContextFactory.remove(Ctx, D);
553 NewCtx = ContextFactory.add(NewCtx, D, newID);
554 VarDefinitions.push_back(VarDefinition(D, Exp, Ctx));
560 // Removes a definition from the context, but keeps the variable name
561 // as a valid variable. The index 0 is a placeholder for cleared definitions.
562 Context clearDefinition(NamedDecl *D, Context Ctx) {
563 Context NewCtx = Ctx;
564 if (NewCtx.contains(D)) {
565 NewCtx = ContextFactory.remove(NewCtx, D);
566 NewCtx = ContextFactory.add(NewCtx, D, 0);
571 // Remove a definition entirely frmo the context.
572 Context removeDefinition(NamedDecl *D, Context Ctx) {
573 Context NewCtx = Ctx;
574 if (NewCtx.contains(D)) {
575 NewCtx = ContextFactory.remove(NewCtx, D);
580 Context intersectContexts(Context C1, Context C2);
581 Context createReferenceContext(Context C);
582 void intersectBackEdge(Context C1, Context C2);
584 friend class VarMapBuilder;
588 // This has to be defined after LocalVariableMap.
589 CFGBlockInfo CFGBlockInfo::getEmptyBlockInfo(Lockset::Factory &F,
590 LocalVariableMap &M) {
591 return CFGBlockInfo(F.getEmptyMap(), M.getEmptyContext());
595 /// Visitor which builds a LocalVariableMap
596 class VarMapBuilder : public StmtVisitor<VarMapBuilder> {
598 LocalVariableMap* VMap;
599 LocalVariableMap::Context Ctx;
601 VarMapBuilder(LocalVariableMap *VM, LocalVariableMap::Context C)
602 : VMap(VM), Ctx(C) {}
604 void VisitDeclStmt(DeclStmt *S);
605 void VisitBinaryOperator(BinaryOperator *BO);
609 // Add new local variables to the variable map
610 void VarMapBuilder::VisitDeclStmt(DeclStmt *S) {
611 bool modifiedCtx = false;
612 DeclGroupRef DGrp = S->getDeclGroup();
613 for (DeclGroupRef::iterator I = DGrp.begin(), E = DGrp.end(); I != E; ++I) {
614 if (VarDecl *VD = dyn_cast_or_null<VarDecl>(*I)) {
615 Expr *E = VD->getInit();
617 // Add local variables with trivial type to the variable map
618 QualType T = VD->getType();
619 if (T.isTrivialType(VD->getASTContext())) {
620 Ctx = VMap->addDefinition(VD, E, Ctx);
626 VMap->saveContext(S, Ctx);
629 // Update local variable definitions in variable map
630 void VarMapBuilder::VisitBinaryOperator(BinaryOperator *BO) {
631 if (!BO->isAssignmentOp())
634 Expr *LHSExp = BO->getLHS()->IgnoreParenCasts();
636 // Update the variable map and current context.
637 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(LHSExp)) {
638 ValueDecl *VDec = DRE->getDecl();
639 if (Ctx.lookup(VDec)) {
640 if (BO->getOpcode() == BO_Assign)
641 Ctx = VMap->updateDefinition(VDec, BO->getRHS(), Ctx);
643 // FIXME -- handle compound assignment operators
644 Ctx = VMap->clearDefinition(VDec, Ctx);
645 VMap->saveContext(BO, Ctx);
651 // Computes the intersection of two contexts. The intersection is the
652 // set of variables which have the same definition in both contexts;
653 // variables with different definitions are discarded.
654 LocalVariableMap::Context
655 LocalVariableMap::intersectContexts(Context C1, Context C2) {
657 for (Context::iterator I = C1.begin(), E = C1.end(); I != E; ++I) {
658 NamedDecl *Dec = I.getKey();
659 unsigned i1 = I.getData();
660 const unsigned *i2 = C2.lookup(Dec);
661 if (!i2) // variable doesn't exist on second path
662 Result = removeDefinition(Dec, Result);
663 else if (*i2 != i1) // variable exists, but has different definition
664 Result = clearDefinition(Dec, Result);
669 // For every variable in C, create a new variable that refers to the
670 // definition in C. Return a new context that contains these new variables.
671 // (We use this for a naive implementation of SSA on loop back-edges.)
672 LocalVariableMap::Context LocalVariableMap::createReferenceContext(Context C) {
673 Context Result = getEmptyContext();
674 for (Context::iterator I = C.begin(), E = C.end(); I != E; ++I) {
675 NamedDecl *Dec = I.getKey();
676 unsigned i = I.getData();
677 Result = addReference(Dec, i, Result);
682 // This routine also takes the intersection of C1 and C2, but it does so by
683 // altering the VarDefinitions. C1 must be the result of an earlier call to
684 // createReferenceContext.
685 void LocalVariableMap::intersectBackEdge(Context C1, Context C2) {
686 for (Context::iterator I = C1.begin(), E = C1.end(); I != E; ++I) {
687 NamedDecl *Dec = I.getKey();
688 unsigned i1 = I.getData();
689 VarDefinition *VDef = &VarDefinitions[i1];
690 assert(VDef->isReference());
692 const unsigned *i2 = C2.lookup(Dec);
693 if (!i2 || (*i2 != i1))
694 VDef->Ref = 0; // Mark this variable as undefined
699 // Traverse the CFG in topological order, so all predecessors of a block
700 // (excluding back-edges) are visited before the block itself. At
701 // each point in the code, we calculate a Context, which holds the set of
702 // variable definitions which are visible at that point in execution.
703 // Visible variables are mapped to their definitions using an array that
704 // contains all definitions.
706 // At join points in the CFG, the set is computed as the intersection of
707 // the incoming sets along each edge, E.g.
709 // { Context | VarDefinitions }
710 // int x = 0; { x -> x1 | x1 = 0 }
711 // int y = 0; { x -> x1, y -> y1 | y1 = 0, x1 = 0 }
712 // if (b) x = 1; { x -> x2, y -> y1 | x2 = 1, y1 = 0, ... }
713 // else x = 2; { x -> x3, y -> y1 | x3 = 2, x2 = 1, ... }
714 // ... { y -> y1 (x is unknown) | x3 = 2, x2 = 1, ... }
716 // This is essentially a simpler and more naive version of the standard SSA
717 // algorithm. Those definitions that remain in the intersection are from blocks
718 // that strictly dominate the current block. We do not bother to insert proper
719 // phi nodes, because they are not used in our analysis; instead, wherever
720 // a phi node would be required, we simply remove that definition from the
721 // context (E.g. x above).
723 // The initial traversal does not capture back-edges, so those need to be
724 // handled on a separate pass. Whenever the first pass encounters an
725 // incoming back edge, it duplicates the context, creating new definitions
726 // that refer back to the originals. (These correspond to places where SSA
727 // might have to insert a phi node.) On the second pass, these definitions are
728 // set to NULL if the the variable has changed on the back-edge (i.e. a phi
729 // node was actually required.) E.g.
731 // { Context | VarDefinitions }
732 // int x = 0, y = 0; { x -> x1, y -> y1 | y1 = 0, x1 = 0 }
733 // while (b) { x -> x2, y -> y1 | [1st:] x2=x1; [2nd:] x2=NULL; }
734 // x = x+1; { x -> x3, y -> y1 | x3 = x2 + 1, ... }
735 // ... { y -> y1 | x3 = 2, x2 = 1, ... }
737 void LocalVariableMap::traverseCFG(CFG *CFGraph,
738 PostOrderCFGView *SortedGraph,
739 std::vector<CFGBlockInfo> &BlockInfo) {
740 PostOrderCFGView::CFGBlockSet VisitedBlocks(CFGraph);
742 CtxIndices.resize(CFGraph->getNumBlockIDs());
744 for (PostOrderCFGView::iterator I = SortedGraph->begin(),
745 E = SortedGraph->end(); I!= E; ++I) {
746 const CFGBlock *CurrBlock = *I;
747 int CurrBlockID = CurrBlock->getBlockID();
748 CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlockID];
750 VisitedBlocks.insert(CurrBlock);
752 // Calculate the entry context for the current block
753 bool HasBackEdges = false;
755 for (CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
756 PE = CurrBlock->pred_end(); PI != PE; ++PI) {
757 // if *PI -> CurrBlock is a back edge, so skip it
758 if (*PI == 0 || !VisitedBlocks.alreadySet(*PI)) {
763 int PrevBlockID = (*PI)->getBlockID();
764 CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
767 CurrBlockInfo->EntryContext = PrevBlockInfo->ExitContext;
771 CurrBlockInfo->EntryContext =
772 intersectContexts(CurrBlockInfo->EntryContext,
773 PrevBlockInfo->ExitContext);
777 // Duplicate the context if we have back-edges, so we can call
778 // intersectBackEdges later.
780 CurrBlockInfo->EntryContext =
781 createReferenceContext(CurrBlockInfo->EntryContext);
783 // Create a starting context index for the current block
784 saveContext(0, CurrBlockInfo->EntryContext);
785 CurrBlockInfo->EntryIndex = getContextIndex();
787 // Visit all the statements in the basic block.
788 VarMapBuilder VMapBuilder(this, CurrBlockInfo->EntryContext);
789 for (CFGBlock::const_iterator BI = CurrBlock->begin(),
790 BE = CurrBlock->end(); BI != BE; ++BI) {
791 switch (BI->getKind()) {
792 case CFGElement::Statement: {
793 const CFGStmt *CS = cast<CFGStmt>(&*BI);
794 VMapBuilder.Visit(const_cast<Stmt*>(CS->getStmt()));
801 CurrBlockInfo->ExitContext = VMapBuilder.Ctx;
803 // Mark variables on back edges as "unknown" if they've been changed.
804 for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
805 SE = CurrBlock->succ_end(); SI != SE; ++SI) {
806 // if CurrBlock -> *SI is *not* a back edge
807 if (*SI == 0 || !VisitedBlocks.alreadySet(*SI))
810 CFGBlock *FirstLoopBlock = *SI;
811 Context LoopBegin = BlockInfo[FirstLoopBlock->getBlockID()].EntryContext;
812 Context LoopEnd = CurrBlockInfo->ExitContext;
813 intersectBackEdge(LoopBegin, LoopEnd);
817 // Put an extra entry at the end of the indexed context array
818 unsigned exitID = CFGraph->getExit().getBlockID();
819 saveContext(0, BlockInfo[exitID].ExitContext);
822 /// Find the appropriate source locations to use when producing diagnostics for
823 /// each block in the CFG.
824 static void findBlockLocations(CFG *CFGraph,
825 PostOrderCFGView *SortedGraph,
826 std::vector<CFGBlockInfo> &BlockInfo) {
827 for (PostOrderCFGView::iterator I = SortedGraph->begin(),
828 E = SortedGraph->end(); I!= E; ++I) {
829 const CFGBlock *CurrBlock = *I;
830 CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlock->getBlockID()];
832 // Find the source location of the last statement in the block, if the
833 // block is not empty.
834 if (const Stmt *S = CurrBlock->getTerminator()) {
835 CurrBlockInfo->EntryLoc = CurrBlockInfo->ExitLoc = S->getLocStart();
837 for (CFGBlock::const_reverse_iterator BI = CurrBlock->rbegin(),
838 BE = CurrBlock->rend(); BI != BE; ++BI) {
839 // FIXME: Handle other CFGElement kinds.
840 if (const CFGStmt *CS = dyn_cast<CFGStmt>(&*BI)) {
841 CurrBlockInfo->ExitLoc = CS->getStmt()->getLocStart();
847 if (!CurrBlockInfo->ExitLoc.isInvalid()) {
848 // This block contains at least one statement. Find the source location
849 // of the first statement in the block.
850 for (CFGBlock::const_iterator BI = CurrBlock->begin(),
851 BE = CurrBlock->end(); BI != BE; ++BI) {
852 // FIXME: Handle other CFGElement kinds.
853 if (const CFGStmt *CS = dyn_cast<CFGStmt>(&*BI)) {
854 CurrBlockInfo->EntryLoc = CS->getStmt()->getLocStart();
858 } else if (CurrBlock->pred_size() == 1 && *CurrBlock->pred_begin() &&
859 CurrBlock != &CFGraph->getExit()) {
860 // The block is empty, and has a single predecessor. Use its exit
862 CurrBlockInfo->EntryLoc = CurrBlockInfo->ExitLoc =
863 BlockInfo[(*CurrBlock->pred_begin())->getBlockID()].ExitLoc;
868 /// \brief Class which implements the core thread safety analysis routines.
869 class ThreadSafetyAnalyzer {
870 friend class BuildLockset;
872 ThreadSafetyHandler &Handler;
873 Lockset::Factory LocksetFactory;
874 LocalVariableMap LocalVarMap;
877 ThreadSafetyAnalyzer(ThreadSafetyHandler &H) : Handler(H) {}
879 Lockset intersectAndWarn(const CFGBlockInfo &Block1, CFGBlockSide Side1,
880 const CFGBlockInfo &Block2, CFGBlockSide Side2,
883 Lockset addLock(Lockset &LSet, Expr *MutexExp, const NamedDecl *D,
884 LockKind LK, SourceLocation Loc);
886 void runAnalysis(AnalysisDeclContext &AC);
890 /// \brief We use this class to visit different types of expressions in
891 /// CFGBlocks, and build up the lockset.
892 /// An expression may cause us to add or remove locks from the lockset, or else
893 /// output error messages related to missing locks.
894 /// FIXME: In future, we may be able to not inherit from a visitor.
895 class BuildLockset : public StmtVisitor<BuildLockset> {
896 friend class ThreadSafetyAnalyzer;
898 ThreadSafetyHandler &Handler;
899 Lockset::Factory &LocksetFactory;
900 LocalVariableMap &LocalVarMap;
903 LocalVariableMap::Context LVarCtx;
907 void addLock(const MutexID &Mutex, const LockData &LDat);
908 void removeLock(const MutexID &Mutex, SourceLocation UnlockLoc);
910 template <class AttrType>
911 void addLocksToSet(LockKind LK, AttrType *Attr,
912 Expr *Exp, NamedDecl *D, VarDecl *VD = 0);
913 void removeLocksFromSet(UnlockFunctionAttr *Attr,
914 Expr *Exp, NamedDecl* FunDecl);
916 const ValueDecl *getValueDecl(Expr *Exp);
917 void warnIfMutexNotHeld (const NamedDecl *D, Expr *Exp, AccessKind AK,
918 Expr *MutexExp, ProtectedOperationKind POK);
919 void checkAccess(Expr *Exp, AccessKind AK);
920 void checkDereference(Expr *Exp, AccessKind AK);
921 void handleCall(Expr *Exp, NamedDecl *D, VarDecl *VD = 0);
923 template <class AttrType>
924 void addTrylock(LockKind LK, AttrType *Attr, Expr *Exp, NamedDecl *FunDecl,
925 const CFGBlock* PredBlock, const CFGBlock *CurrBlock,
926 Expr *BrE, bool Neg);
927 CallExpr* getTrylockCallExpr(Stmt *Cond, LocalVariableMap::Context C,
929 void handleTrylock(Stmt *Cond, const CFGBlock* PredBlock,
930 const CFGBlock *CurrBlock);
932 /// \brief Returns true if the lockset contains a lock, regardless of whether
933 /// the lock is held exclusively or shared.
934 bool locksetContains(const MutexID &Lock) const {
935 return LSet.lookup(Lock);
938 /// \brief Returns true if the lockset contains a lock with the passed in
940 bool locksetContains(const MutexID &Lock, LockKind KindRequested) const {
941 const LockData *LockHeld = LSet.lookup(Lock);
942 return (LockHeld && KindRequested == LockHeld->LKind);
945 /// \brief Returns true if the lockset contains a lock with at least the
946 /// passed in locktype. So for example, if we pass in LK_Shared, this function
947 /// returns true if the lock is held LK_Shared or LK_Exclusive. If we pass in
948 /// LK_Exclusive, this function returns true if the lock is held LK_Exclusive.
949 bool locksetContainsAtLeast(const MutexID &Lock,
950 LockKind KindRequested) const {
951 switch (KindRequested) {
953 return locksetContains(Lock);
955 return locksetContains(Lock, KindRequested);
957 llvm_unreachable("Unknown LockKind");
961 BuildLockset(ThreadSafetyAnalyzer *analyzer, CFGBlockInfo &Info)
962 : StmtVisitor<BuildLockset>(),
963 Handler(analyzer->Handler),
964 LocksetFactory(analyzer->LocksetFactory),
965 LocalVarMap(analyzer->LocalVarMap),
967 LVarCtx(Info.EntryContext),
968 CtxIndex(Info.EntryIndex)
971 void VisitUnaryOperator(UnaryOperator *UO);
972 void VisitBinaryOperator(BinaryOperator *BO);
973 void VisitCastExpr(CastExpr *CE);
974 void VisitCallExpr(CallExpr *Exp);
975 void VisitCXXConstructExpr(CXXConstructExpr *Exp);
976 void VisitDeclStmt(DeclStmt *S);
979 /// \brief Add a new lock to the lockset, warning if the lock is already there.
980 /// \param Mutex -- the Mutex expression for the lock
981 /// \param LDat -- the LockData for the lock
982 void BuildLockset::addLock(const MutexID &Mutex, const LockData& LDat) {
983 // FIXME: deal with acquired before/after annotations.
984 // FIXME: Don't always warn when we have support for reentrant locks.
985 if (locksetContains(Mutex))
986 Handler.handleDoubleLock(Mutex.getName(), LDat.AcquireLoc);
988 LSet = LocksetFactory.add(LSet, Mutex, LDat);
991 /// \brief Remove a lock from the lockset, warning if the lock is not there.
992 /// \param LockExp The lock expression corresponding to the lock to be removed
993 /// \param UnlockLoc The source location of the unlock (only used in error msg)
994 void BuildLockset::removeLock(const MutexID &Mutex, SourceLocation UnlockLoc) {
995 const LockData *LDat = LSet.lookup(Mutex);
997 Handler.handleUnmatchedUnlock(Mutex.getName(), UnlockLoc);
999 // For scoped-lockable vars, remove the mutex associated with this var.
1000 if (LDat->UnderlyingMutex.isValid())
1001 removeLock(LDat->UnderlyingMutex, UnlockLoc);
1002 LSet = LocksetFactory.remove(LSet, Mutex);
1006 /// \brief This function, parameterized by an attribute type, is used to add a
1007 /// set of locks specified as attribute arguments to the lockset.
1008 template <typename AttrType>
1009 void BuildLockset::addLocksToSet(LockKind LK, AttrType *Attr,
1010 Expr *Exp, NamedDecl* FunDecl, VarDecl *VD) {
1011 typedef typename AttrType::args_iterator iterator_type;
1013 SourceLocation ExpLocation = Exp->getExprLoc();
1015 // Figure out if we're calling the constructor of scoped lockable class
1016 bool isScopedVar = false;
1018 if (CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FunDecl)) {
1019 CXXRecordDecl* PD = CD->getParent();
1020 if (PD && PD->getAttr<ScopedLockableAttr>())
1025 if (Attr->args_size() == 0) {
1026 // The mutex held is the "this" object.
1027 MutexID Mutex(0, Exp, FunDecl);
1028 if (!Mutex.isValid())
1029 MutexID::warnInvalidLock(Handler, 0, Exp, FunDecl);
1031 addLock(Mutex, LockData(ExpLocation, LK));
1035 for (iterator_type I=Attr->args_begin(), E=Attr->args_end(); I != E; ++I) {
1036 MutexID Mutex(*I, Exp, FunDecl);
1037 if (!Mutex.isValid())
1038 MutexID::warnInvalidLock(Handler, *I, Exp, FunDecl);
1040 addLock(Mutex, LockData(ExpLocation, LK));
1042 // For scoped lockable vars, map this var to its underlying mutex.
1043 DeclRefExpr DRE(VD, false, VD->getType(), VK_LValue, VD->getLocation());
1044 MutexID SMutex(&DRE, 0, 0);
1045 addLock(SMutex, LockData(VD->getLocation(), LK, Mutex));
1051 /// \brief This function removes a set of locks specified as attribute
1052 /// arguments from the lockset.
1053 void BuildLockset::removeLocksFromSet(UnlockFunctionAttr *Attr,
1054 Expr *Exp, NamedDecl* FunDecl) {
1055 SourceLocation ExpLocation;
1056 if (Exp) ExpLocation = Exp->getExprLoc();
1058 if (Attr->args_size() == 0) {
1059 // The mutex held is the "this" object.
1060 MutexID Mu(0, Exp, FunDecl);
1062 MutexID::warnInvalidLock(Handler, 0, Exp, FunDecl);
1064 removeLock(Mu, ExpLocation);
1068 for (UnlockFunctionAttr::args_iterator I = Attr->args_begin(),
1069 E = Attr->args_end(); I != E; ++I) {
1070 MutexID Mutex(*I, Exp, FunDecl);
1071 if (!Mutex.isValid())
1072 MutexID::warnInvalidLock(Handler, *I, Exp, FunDecl);
1074 removeLock(Mutex, ExpLocation);
1078 /// \brief Gets the value decl pointer from DeclRefExprs or MemberExprs
1079 const ValueDecl *BuildLockset::getValueDecl(Expr *Exp) {
1080 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Exp))
1081 return DR->getDecl();
1083 if (const MemberExpr *ME = dyn_cast<MemberExpr>(Exp))
1084 return ME->getMemberDecl();
1089 /// \brief Warn if the LSet does not contain a lock sufficient to protect access
1090 /// of at least the passed in AccessKind.
1091 void BuildLockset::warnIfMutexNotHeld(const NamedDecl *D, Expr *Exp,
1092 AccessKind AK, Expr *MutexExp,
1093 ProtectedOperationKind POK) {
1094 LockKind LK = getLockKindFromAccessKind(AK);
1096 MutexID Mutex(MutexExp, Exp, D);
1097 if (!Mutex.isValid())
1098 MutexID::warnInvalidLock(Handler, MutexExp, Exp, D);
1099 else if (!locksetContainsAtLeast(Mutex, LK))
1100 Handler.handleMutexNotHeld(D, POK, Mutex.getName(), LK, Exp->getExprLoc());
1103 /// \brief This method identifies variable dereferences and checks pt_guarded_by
1104 /// and pt_guarded_var annotations. Note that we only check these annotations
1105 /// at the time a pointer is dereferenced.
1106 /// FIXME: We need to check for other types of pointer dereferences
1107 /// (e.g. [], ->) and deal with them here.
1108 /// \param Exp An expression that has been read or written.
1109 void BuildLockset::checkDereference(Expr *Exp, AccessKind AK) {
1110 UnaryOperator *UO = dyn_cast<UnaryOperator>(Exp);
1111 if (!UO || UO->getOpcode() != clang::UO_Deref)
1113 Exp = UO->getSubExpr()->IgnoreParenCasts();
1115 const ValueDecl *D = getValueDecl(Exp);
1116 if(!D || !D->hasAttrs())
1119 if (D->getAttr<PtGuardedVarAttr>() && LSet.isEmpty())
1120 Handler.handleNoMutexHeld(D, POK_VarDereference, AK, Exp->getExprLoc());
1122 const AttrVec &ArgAttrs = D->getAttrs();
1123 for(unsigned i = 0, Size = ArgAttrs.size(); i < Size; ++i)
1124 if (PtGuardedByAttr *PGBAttr = dyn_cast<PtGuardedByAttr>(ArgAttrs[i]))
1125 warnIfMutexNotHeld(D, Exp, AK, PGBAttr->getArg(), POK_VarDereference);
1128 /// \brief Checks guarded_by and guarded_var attributes.
1129 /// Whenever we identify an access (read or write) of a DeclRefExpr or
1130 /// MemberExpr, we need to check whether there are any guarded_by or
1131 /// guarded_var attributes, and make sure we hold the appropriate mutexes.
1132 void BuildLockset::checkAccess(Expr *Exp, AccessKind AK) {
1133 const ValueDecl *D = getValueDecl(Exp);
1134 if(!D || !D->hasAttrs())
1137 if (D->getAttr<GuardedVarAttr>() && LSet.isEmpty())
1138 Handler.handleNoMutexHeld(D, POK_VarAccess, AK, Exp->getExprLoc());
1140 const AttrVec &ArgAttrs = D->getAttrs();
1141 for(unsigned i = 0, Size = ArgAttrs.size(); i < Size; ++i)
1142 if (GuardedByAttr *GBAttr = dyn_cast<GuardedByAttr>(ArgAttrs[i]))
1143 warnIfMutexNotHeld(D, Exp, AK, GBAttr->getArg(), POK_VarAccess);
1146 /// \brief Process a function call, method call, constructor call,
1147 /// or destructor call. This involves looking at the attributes on the
1148 /// corresponding function/method/constructor/destructor, issuing warnings,
1149 /// and updating the locksets accordingly.
1151 /// FIXME: For classes annotated with one of the guarded annotations, we need
1152 /// to treat const method calls as reads and non-const method calls as writes,
1153 /// and check that the appropriate locks are held. Non-const method calls with
1154 /// the same signature as const method calls can be also treated as reads.
1156 /// FIXME: We need to also visit CallExprs to catch/check global functions.
1158 /// FIXME: Do not flag an error for member variables accessed in constructors/
1160 void BuildLockset::handleCall(Expr *Exp, NamedDecl *D, VarDecl *VD) {
1161 AttrVec &ArgAttrs = D->getAttrs();
1162 for(unsigned i = 0; i < ArgAttrs.size(); ++i) {
1163 Attr *Attr = ArgAttrs[i];
1164 switch (Attr->getKind()) {
1165 // When we encounter an exclusive lock function, we need to add the lock
1166 // to our lockset with kind exclusive.
1167 case attr::ExclusiveLockFunction: {
1168 ExclusiveLockFunctionAttr *A = cast<ExclusiveLockFunctionAttr>(Attr);
1169 addLocksToSet(LK_Exclusive, A, Exp, D, VD);
1173 // When we encounter a shared lock function, we need to add the lock
1174 // to our lockset with kind shared.
1175 case attr::SharedLockFunction: {
1176 SharedLockFunctionAttr *A = cast<SharedLockFunctionAttr>(Attr);
1177 addLocksToSet(LK_Shared, A, Exp, D, VD);
1181 // When we encounter an unlock function, we need to remove unlocked
1182 // mutexes from the lockset, and flag a warning if they are not there.
1183 case attr::UnlockFunction: {
1184 UnlockFunctionAttr *UFAttr = cast<UnlockFunctionAttr>(Attr);
1185 removeLocksFromSet(UFAttr, Exp, D);
1189 case attr::ExclusiveLocksRequired: {
1190 ExclusiveLocksRequiredAttr *ELRAttr =
1191 cast<ExclusiveLocksRequiredAttr>(Attr);
1193 for (ExclusiveLocksRequiredAttr::args_iterator
1194 I = ELRAttr->args_begin(), E = ELRAttr->args_end(); I != E; ++I)
1195 warnIfMutexNotHeld(D, Exp, AK_Written, *I, POK_FunctionCall);
1199 case attr::SharedLocksRequired: {
1200 SharedLocksRequiredAttr *SLRAttr = cast<SharedLocksRequiredAttr>(Attr);
1202 for (SharedLocksRequiredAttr::args_iterator I = SLRAttr->args_begin(),
1203 E = SLRAttr->args_end(); I != E; ++I)
1204 warnIfMutexNotHeld(D, Exp, AK_Read, *I, POK_FunctionCall);
1208 case attr::LocksExcluded: {
1209 LocksExcludedAttr *LEAttr = cast<LocksExcludedAttr>(Attr);
1210 for (LocksExcludedAttr::args_iterator I = LEAttr->args_begin(),
1211 E = LEAttr->args_end(); I != E; ++I) {
1212 MutexID Mutex(*I, Exp, D);
1213 if (!Mutex.isValid())
1214 MutexID::warnInvalidLock(Handler, *I, Exp, D);
1215 else if (locksetContains(Mutex))
1216 Handler.handleFunExcludesLock(D->getName(), Mutex.getName(),
1222 // Ignore other (non thread-safety) attributes
1230 /// \brief Add lock to set, if the current block is in the taken branch of a
1232 template <class AttrType>
1233 void BuildLockset::addTrylock(LockKind LK, AttrType *Attr, Expr *Exp,
1234 NamedDecl *FunDecl, const CFGBlock *PredBlock,
1235 const CFGBlock *CurrBlock, Expr *BrE, bool Neg) {
1236 // Find out which branch has the lock
1238 if (CXXBoolLiteralExpr *BLE = dyn_cast_or_null<CXXBoolLiteralExpr>(BrE)) {
1239 branch = BLE->getValue();
1241 else if (IntegerLiteral *ILE = dyn_cast_or_null<IntegerLiteral>(BrE)) {
1242 branch = ILE->getValue().getBoolValue();
1244 int branchnum = branch ? 0 : 1;
1245 if (Neg) branchnum = !branchnum;
1247 // If we've taken the trylock branch, then add the lock
1249 for (CFGBlock::const_succ_iterator SI = PredBlock->succ_begin(),
1250 SE = PredBlock->succ_end(); SI != SE && i < 2; ++SI, ++i) {
1251 if (*SI == CurrBlock && i == branchnum) {
1252 addLocksToSet(LK, Attr, Exp, FunDecl, 0);
1258 // If Cond can be traced back to a function call, return the call expression.
1259 // The negate variable should be called with false, and will be set to true
1260 // if the function call is negated, e.g. if (!mu.tryLock(...))
1261 CallExpr* BuildLockset::getTrylockCallExpr(Stmt *Cond,
1262 LocalVariableMap::Context C,
1267 if (CallExpr *CallExp = dyn_cast<CallExpr>(Cond)) {
1270 else if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(Cond)) {
1271 return getTrylockCallExpr(CE->getSubExpr(), C, Negate);
1273 else if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Cond)) {
1274 Expr *E = LocalVarMap.lookupExpr(DRE->getDecl(), C);
1275 return getTrylockCallExpr(E, C, Negate);
1277 else if (UnaryOperator *UOP = dyn_cast<UnaryOperator>(Cond)) {
1278 if (UOP->getOpcode() == UO_LNot) {
1280 return getTrylockCallExpr(UOP->getSubExpr(), C, Negate);
1283 // FIXME -- handle && and || as well.
1288 /// \brief Process a conditional branch from a previous block to the current
1289 /// block, looking for trylock calls.
1290 void BuildLockset::handleTrylock(Stmt *Cond, const CFGBlock *PredBlock,
1291 const CFGBlock *CurrBlock) {
1292 bool Negate = false;
1293 CallExpr *Exp = getTrylockCallExpr(Cond, LVarCtx, Negate);
1297 NamedDecl *FunDecl = dyn_cast_or_null<NamedDecl>(Exp->getCalleeDecl());
1298 if(!FunDecl || !FunDecl->hasAttrs())
1301 // If the condition is a call to a Trylock function, then grab the attributes
1302 AttrVec &ArgAttrs = FunDecl->getAttrs();
1303 for (unsigned i = 0; i < ArgAttrs.size(); ++i) {
1304 Attr *Attr = ArgAttrs[i];
1305 switch (Attr->getKind()) {
1306 case attr::ExclusiveTrylockFunction: {
1307 ExclusiveTrylockFunctionAttr *A =
1308 cast<ExclusiveTrylockFunctionAttr>(Attr);
1309 addTrylock(LK_Exclusive, A, Exp, FunDecl, PredBlock, CurrBlock,
1310 A->getSuccessValue(), Negate);
1313 case attr::SharedTrylockFunction: {
1314 SharedTrylockFunctionAttr *A =
1315 cast<SharedTrylockFunctionAttr>(Attr);
1316 addTrylock(LK_Shared, A, Exp, FunDecl, PredBlock, CurrBlock,
1317 A->getSuccessValue(), Negate);
1327 /// \brief For unary operations which read and write a variable, we need to
1328 /// check whether we hold any required mutexes. Reads are checked in
1330 void BuildLockset::VisitUnaryOperator(UnaryOperator *UO) {
1331 switch (UO->getOpcode()) {
1332 case clang::UO_PostDec:
1333 case clang::UO_PostInc:
1334 case clang::UO_PreDec:
1335 case clang::UO_PreInc: {
1336 Expr *SubExp = UO->getSubExpr()->IgnoreParenCasts();
1337 checkAccess(SubExp, AK_Written);
1338 checkDereference(SubExp, AK_Written);
1346 /// For binary operations which assign to a variable (writes), we need to check
1347 /// whether we hold any required mutexes.
1348 /// FIXME: Deal with non-primitive types.
1349 void BuildLockset::VisitBinaryOperator(BinaryOperator *BO) {
1350 if (!BO->isAssignmentOp())
1353 // adjust the context
1354 LVarCtx = LocalVarMap.getNextContext(CtxIndex, BO, LVarCtx);
1356 Expr *LHSExp = BO->getLHS()->IgnoreParenCasts();
1357 checkAccess(LHSExp, AK_Written);
1358 checkDereference(LHSExp, AK_Written);
1361 /// Whenever we do an LValue to Rvalue cast, we are reading a variable and
1362 /// need to ensure we hold any required mutexes.
1363 /// FIXME: Deal with non-primitive types.
1364 void BuildLockset::VisitCastExpr(CastExpr *CE) {
1365 if (CE->getCastKind() != CK_LValueToRValue)
1367 Expr *SubExp = CE->getSubExpr()->IgnoreParenCasts();
1368 checkAccess(SubExp, AK_Read);
1369 checkDereference(SubExp, AK_Read);
1373 void BuildLockset::VisitCallExpr(CallExpr *Exp) {
1374 NamedDecl *D = dyn_cast_or_null<NamedDecl>(Exp->getCalleeDecl());
1375 if(!D || !D->hasAttrs())
1380 void BuildLockset::VisitCXXConstructExpr(CXXConstructExpr *Exp) {
1381 // FIXME -- only handles constructors in DeclStmt below.
1384 void BuildLockset::VisitDeclStmt(DeclStmt *S) {
1385 // adjust the context
1386 LVarCtx = LocalVarMap.getNextContext(CtxIndex, S, LVarCtx);
1388 DeclGroupRef DGrp = S->getDeclGroup();
1389 for (DeclGroupRef::iterator I = DGrp.begin(), E = DGrp.end(); I != E; ++I) {
1391 if (VarDecl *VD = dyn_cast_or_null<VarDecl>(D)) {
1392 Expr *E = VD->getInit();
1393 if (CXXConstructExpr *CE = dyn_cast_or_null<CXXConstructExpr>(E)) {
1394 NamedDecl *CtorD = dyn_cast_or_null<NamedDecl>(CE->getConstructor());
1395 if (!CtorD || !CtorD->hasAttrs())
1397 handleCall(CE, CtorD, VD);
1404 /// \brief Compute the intersection of two locksets and issue warnings for any
1405 /// locks in the symmetric difference.
1407 /// This function is used at a merge point in the CFG when comparing the lockset
1408 /// of each branch being merged. For example, given the following sequence:
1409 /// A; if () then B; else C; D; we need to check that the lockset after B and C
1410 /// are the same. In the event of a difference, we use the intersection of these
1411 /// two locksets at the start of D.
1412 Lockset ThreadSafetyAnalyzer::intersectAndWarn(const CFGBlockInfo &Block1,
1414 const CFGBlockInfo &Block2,
1416 LockErrorKind LEK) {
1417 Lockset LSet1 = Block1.getSet(Side1);
1418 Lockset LSet2 = Block2.getSet(Side2);
1420 Lockset Intersection = LSet1;
1421 for (Lockset::iterator I = LSet2.begin(), E = LSet2.end(); I != E; ++I) {
1422 const MutexID &LSet2Mutex = I.getKey();
1423 const LockData &LSet2LockData = I.getData();
1424 if (const LockData *LD = LSet1.lookup(LSet2Mutex)) {
1425 if (LD->LKind != LSet2LockData.LKind) {
1426 Handler.handleExclusiveAndShared(LSet2Mutex.getName(),
1427 LSet2LockData.AcquireLoc,
1429 if (LD->LKind != LK_Exclusive)
1430 Intersection = LocksetFactory.add(Intersection, LSet2Mutex,
1434 Handler.handleMutexHeldEndOfScope(LSet2Mutex.getName(),
1435 LSet2LockData.AcquireLoc,
1436 Block1.getLocation(Side1), LEK);
1440 for (Lockset::iterator I = LSet1.begin(), E = LSet1.end(); I != E; ++I) {
1441 if (!LSet2.contains(I.getKey())) {
1442 const MutexID &Mutex = I.getKey();
1443 const LockData &MissingLock = I.getData();
1444 Handler.handleMutexHeldEndOfScope(Mutex.getName(),
1445 MissingLock.AcquireLoc,
1446 Block2.getLocation(Side2), LEK);
1447 Intersection = LocksetFactory.remove(Intersection, Mutex);
1450 return Intersection;
1453 Lockset ThreadSafetyAnalyzer::addLock(Lockset &LSet, Expr *MutexExp,
1455 LockKind LK, SourceLocation Loc) {
1456 MutexID Mutex(MutexExp, 0, D);
1457 if (!Mutex.isValid()) {
1458 MutexID::warnInvalidLock(Handler, MutexExp, 0, D);
1461 LockData NewLock(Loc, LK);
1462 return LocksetFactory.add(LSet, Mutex, NewLock);
1465 /// \brief Check a function's CFG for thread-safety violations.
1467 /// We traverse the blocks in the CFG, compute the set of mutexes that are held
1468 /// at the end of each block, and issue warnings for thread safety violations.
1469 /// Each block in the CFG is traversed exactly once.
1470 void ThreadSafetyAnalyzer::runAnalysis(AnalysisDeclContext &AC) {
1471 CFG *CFGraph = AC.getCFG();
1472 if (!CFGraph) return;
1473 const NamedDecl *D = dyn_cast_or_null<NamedDecl>(AC.getDecl());
1476 return; // Ignore anonymous functions for now.
1477 if (D->getAttr<NoThreadSafetyAnalysisAttr>())
1479 // FIXME: Do something a bit more intelligent inside constructor and
1480 // destructor code. Constructors and destructors must assume unique access
1481 // to 'this', so checks on member variable access is disabled, but we should
1482 // still enable checks on other objects.
1483 if (isa<CXXConstructorDecl>(D))
1484 return; // Don't check inside constructors.
1485 if (isa<CXXDestructorDecl>(D))
1486 return; // Don't check inside destructors.
1488 std::vector<CFGBlockInfo> BlockInfo(CFGraph->getNumBlockIDs(),
1489 CFGBlockInfo::getEmptyBlockInfo(LocksetFactory, LocalVarMap));
1491 // We need to explore the CFG via a "topological" ordering.
1492 // That way, we will be guaranteed to have information about required
1493 // predecessor locksets when exploring a new block.
1494 PostOrderCFGView *SortedGraph = AC.getAnalysis<PostOrderCFGView>();
1495 PostOrderCFGView::CFGBlockSet VisitedBlocks(CFGraph);
1497 // Compute SSA names for local variables
1498 LocalVarMap.traverseCFG(CFGraph, SortedGraph, BlockInfo);
1500 // Fill in source locations for all CFGBlocks.
1501 findBlockLocations(CFGraph, SortedGraph, BlockInfo);
1503 // Add locks from exclusive_locks_required and shared_locks_required
1504 // to initial lockset. Also turn off checking for lock and unlock functions.
1505 // FIXME: is there a more intelligent way to check lock/unlock functions?
1506 if (!SortedGraph->empty() && D->hasAttrs()) {
1507 const CFGBlock *FirstBlock = *SortedGraph->begin();
1508 Lockset &InitialLockset = BlockInfo[FirstBlock->getBlockID()].EntrySet;
1509 const AttrVec &ArgAttrs = D->getAttrs();
1510 for (unsigned i = 0; i < ArgAttrs.size(); ++i) {
1511 Attr *Attr = ArgAttrs[i];
1512 SourceLocation AttrLoc = Attr->getLocation();
1513 if (SharedLocksRequiredAttr *SLRAttr
1514 = dyn_cast<SharedLocksRequiredAttr>(Attr)) {
1515 for (SharedLocksRequiredAttr::args_iterator
1516 SLRIter = SLRAttr->args_begin(),
1517 SLREnd = SLRAttr->args_end(); SLRIter != SLREnd; ++SLRIter)
1518 InitialLockset = addLock(InitialLockset,
1519 *SLRIter, D, LK_Shared,
1521 } else if (ExclusiveLocksRequiredAttr *ELRAttr
1522 = dyn_cast<ExclusiveLocksRequiredAttr>(Attr)) {
1523 for (ExclusiveLocksRequiredAttr::args_iterator
1524 ELRIter = ELRAttr->args_begin(),
1525 ELREnd = ELRAttr->args_end(); ELRIter != ELREnd; ++ELRIter)
1526 InitialLockset = addLock(InitialLockset,
1527 *ELRIter, D, LK_Exclusive,
1529 } else if (isa<UnlockFunctionAttr>(Attr)) {
1530 // Don't try to check unlock functions for now
1532 } else if (isa<ExclusiveLockFunctionAttr>(Attr)) {
1533 // Don't try to check lock functions for now
1535 } else if (isa<SharedLockFunctionAttr>(Attr)) {
1536 // Don't try to check lock functions for now
1542 for (PostOrderCFGView::iterator I = SortedGraph->begin(),
1543 E = SortedGraph->end(); I!= E; ++I) {
1544 const CFGBlock *CurrBlock = *I;
1545 int CurrBlockID = CurrBlock->getBlockID();
1546 CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlockID];
1548 // Use the default initial lockset in case there are no predecessors.
1549 VisitedBlocks.insert(CurrBlock);
1551 // Iterate through the predecessor blocks and warn if the lockset for all
1552 // predecessors is not the same. We take the entry lockset of the current
1553 // block to be the intersection of all previous locksets.
1554 // FIXME: By keeping the intersection, we may output more errors in future
1555 // for a lock which is not in the intersection, but was in the union. We
1556 // may want to also keep the union in future. As an example, let's say
1557 // the intersection contains Mutex L, and the union contains L and M.
1558 // Later we unlock M. At this point, we would output an error because we
1559 // never locked M; although the real error is probably that we forgot to
1560 // lock M on all code paths. Conversely, let's say that later we lock M.
1561 // In this case, we should compare against the intersection instead of the
1562 // union because the real error is probably that we forgot to unlock M on
1564 bool LocksetInitialized = false;
1565 llvm::SmallVector<CFGBlock*, 8> SpecialBlocks;
1566 for (CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
1567 PE = CurrBlock->pred_end(); PI != PE; ++PI) {
1569 // if *PI -> CurrBlock is a back edge
1570 if (*PI == 0 || !VisitedBlocks.alreadySet(*PI))
1573 // Ignore edges from blocks that can't return.
1574 if ((*PI)->hasNoReturnElement())
1577 // If the previous block ended in a 'continue' or 'break' statement, then
1578 // a difference in locksets is probably due to a bug in that block, rather
1579 // than in some other predecessor. In that case, keep the other
1580 // predecessor's lockset.
1581 if (const Stmt *Terminator = (*PI)->getTerminator()) {
1582 if (isa<ContinueStmt>(Terminator) || isa<BreakStmt>(Terminator)) {
1583 SpecialBlocks.push_back(*PI);
1588 int PrevBlockID = (*PI)->getBlockID();
1589 CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
1591 if (!LocksetInitialized) {
1592 CurrBlockInfo->EntrySet = PrevBlockInfo->ExitSet;
1593 LocksetInitialized = true;
1595 CurrBlockInfo->EntrySet =
1596 intersectAndWarn(*CurrBlockInfo, CBS_Entry,
1597 *PrevBlockInfo, CBS_Exit,
1598 LEK_LockedSomePredecessors);
1602 // Process continue and break blocks. Assume that the lockset for the
1603 // resulting block is unaffected by any discrepancies in them.
1604 for (unsigned SpecialI = 0, SpecialN = SpecialBlocks.size();
1605 SpecialI < SpecialN; ++SpecialI) {
1606 CFGBlock *PrevBlock = SpecialBlocks[SpecialI];
1607 int PrevBlockID = PrevBlock->getBlockID();
1608 CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
1610 if (!LocksetInitialized) {
1611 CurrBlockInfo->EntrySet = PrevBlockInfo->ExitSet;
1612 LocksetInitialized = true;
1614 // Determine whether this edge is a loop terminator for diagnostic
1615 // purposes. FIXME: A 'break' statement might be a loop terminator, but
1616 // it might also be part of a switch. Also, a subsequent destructor
1617 // might add to the lockset, in which case the real issue might be a
1618 // double lock on the other path.
1619 const Stmt *Terminator = PrevBlock->getTerminator();
1620 bool IsLoop = Terminator && isa<ContinueStmt>(Terminator);
1622 // Do not update EntrySet.
1623 intersectAndWarn(*CurrBlockInfo, CBS_Entry, *PrevBlockInfo, CBS_Exit,
1624 IsLoop ? LEK_LockedSomeLoopIterations
1625 : LEK_LockedSomePredecessors);
1629 BuildLockset LocksetBuilder(this, *CurrBlockInfo);
1630 CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
1631 PE = CurrBlock->pred_end();
1633 // If the predecessor ended in a branch, then process any trylocks.
1634 // FIXME -- check to make sure there's only one predecessor.
1635 if (Stmt *TCE = (*PI)->getTerminatorCondition()) {
1636 LocksetBuilder.handleTrylock(TCE, *PI, CurrBlock);
1640 // Visit all the statements in the basic block.
1641 for (CFGBlock::const_iterator BI = CurrBlock->begin(),
1642 BE = CurrBlock->end(); BI != BE; ++BI) {
1643 switch (BI->getKind()) {
1644 case CFGElement::Statement: {
1645 const CFGStmt *CS = cast<CFGStmt>(&*BI);
1646 LocksetBuilder.Visit(const_cast<Stmt*>(CS->getStmt()));
1649 // Ignore BaseDtor, MemberDtor, and TemporaryDtor for now.
1650 case CFGElement::AutomaticObjectDtor: {
1651 const CFGAutomaticObjDtor *AD = cast<CFGAutomaticObjDtor>(&*BI);
1652 CXXDestructorDecl *DD = const_cast<CXXDestructorDecl*>(
1653 AD->getDestructorDecl(AC.getASTContext()));
1654 if (!DD->hasAttrs())
1657 // Create a dummy expression,
1658 VarDecl *VD = const_cast<VarDecl*>(AD->getVarDecl());
1659 DeclRefExpr DRE(VD, false, VD->getType(), VK_LValue,
1660 AD->getTriggerStmt()->getLocEnd());
1661 LocksetBuilder.handleCall(&DRE, DD);
1668 CurrBlockInfo->ExitSet = LocksetBuilder.LSet;
1670 // For every back edge from CurrBlock (the end of the loop) to another block
1671 // (FirstLoopBlock) we need to check that the Lockset of Block is equal to
1672 // the one held at the beginning of FirstLoopBlock. We can look up the
1673 // Lockset held at the beginning of FirstLoopBlock in the EntryLockSets map.
1674 for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
1675 SE = CurrBlock->succ_end(); SI != SE; ++SI) {
1677 // if CurrBlock -> *SI is *not* a back edge
1678 if (*SI == 0 || !VisitedBlocks.alreadySet(*SI))
1681 CFGBlock *FirstLoopBlock = *SI;
1682 CFGBlockInfo &PreLoop = BlockInfo[FirstLoopBlock->getBlockID()];
1683 CFGBlockInfo &LoopEnd = BlockInfo[CurrBlockID];
1684 intersectAndWarn(LoopEnd, CBS_Exit, PreLoop, CBS_Entry,
1685 LEK_LockedSomeLoopIterations);
1689 CFGBlockInfo &Initial = BlockInfo[CFGraph->getEntry().getBlockID()];
1690 CFGBlockInfo &Final = BlockInfo[CFGraph->getExit().getBlockID()];
1692 // FIXME: Should we call this function for all blocks which exit the function?
1693 intersectAndWarn(Initial, CBS_Entry, Final, CBS_Exit,
1694 LEK_LockedAtEndOfFunction);
1697 } // end anonymous namespace
1701 namespace thread_safety {
1703 /// \brief Check a function's CFG for thread-safety violations.
1705 /// We traverse the blocks in the CFG, compute the set of mutexes that are held
1706 /// at the end of each block, and issue warnings for thread safety violations.
1707 /// Each block in the CFG is traversed exactly once.
1708 void runThreadSafetyAnalysis(AnalysisDeclContext &AC,
1709 ThreadSafetyHandler &Handler) {
1710 ThreadSafetyAnalyzer Analyzer(Handler);
1711 Analyzer.runAnalysis(AC);
1714 /// \brief Helper function that returns a LockKind required for the given level
1716 LockKind getLockKindFromAccessKind(AccessKind AK) {
1721 return LK_Exclusive;
1723 llvm_unreachable("Unknown AccessKind");
1726 }} // end namespace clang::thread_safety