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/ThreadSafetyAnalysis.html
14 // for more information.
16 //===----------------------------------------------------------------------===//
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"
47 using namespace clang;
48 using namespace threadSafety;
50 // Key method definition
51 ThreadSafetyHandler::~ThreadSafetyHandler() {}
55 public til::PrettyPrinter<TILPrinter, llvm::raw_ostream> {};
58 /// Issue a warning about an invalid lock expression
59 static void warnInvalidLock(ThreadSafetyHandler &Handler,
60 const Expr *MutexExp, const NamedDecl *D,
61 const Expr *DeclExp, StringRef Kind) {
64 Loc = DeclExp->getExprLoc();
66 // FIXME: add a note about the attribute location in MutexExp or D
68 Handler.handleInvalidLockExp(Kind, Loc);
71 /// \brief A set of CapabilityInfo objects, which are compiled from the
72 /// requires attributes on a function.
73 class CapExprSet : public SmallVector<CapabilityExpr, 4> {
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);
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.
94 /// FIXME: this analysis does not currently support either re-entrant
95 /// locking or lock "upgrading" and "downgrading" between exclusive and
97 class FactEntry : public CapabilityExpr {
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
105 FactEntry(const CapabilityExpr &CE, LockKind LK, SourceLocation Loc,
106 bool Asrt, bool Declrd = false)
107 : CapabilityExpr(CE), LKind(LK), AcquireLoc(Loc), Asserted(Asrt),
110 virtual ~FactEntry() {}
112 LockKind kind() const { return LKind; }
113 SourceLocation loc() const { return AcquireLoc; }
114 bool asserted() const { return Asserted; }
115 bool declared() const { return Declared; }
117 void setDeclared(bool D) { Declared = D; }
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;
128 // Return true if LKind >= LK, where exclusive > shared
129 bool isAtLeast(LockKind LK) {
130 return (LKind == LK_Exclusive) || (LK == LK_Shared);
135 typedef unsigned short FactID;
137 /// \brief FactManager manages the memory for all facts that are created during
138 /// the analysis of a single routine.
141 std::vector<std::unique_ptr<FactEntry>> Facts;
144 FactID newFact(std::unique_ptr<FactEntry> Entry) {
145 Facts.push_back(std::move(Entry));
146 return static_cast<unsigned short>(Facts.size() - 1);
149 const FactEntry &operator[](FactID F) const { return *Facts[F]; }
150 FactEntry &operator[](FactID F) { return *Facts[F]; }
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.
163 typedef SmallVector<FactID, 4> FactVec;
168 typedef FactVec::iterator iterator;
169 typedef FactVec::const_iterator const_iterator;
171 iterator begin() { return FactIDs.begin(); }
172 const_iterator begin() const { return FactIDs.begin(); }
174 iterator end() { return FactIDs.end(); }
175 const_iterator end() const { return FactIDs.end(); }
177 bool isEmpty() const { return FactIDs.size() == 0; }
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())
188 void addLockByID(FactID ID) { FactIDs.push_back(ID); }
190 FactID addLock(FactManager &FM, std::unique_ptr<FactEntry> Entry) {
191 FactID F = FM.newFact(std::move(Entry));
192 FactIDs.push_back(F);
196 bool removeLock(FactManager& FM, const CapabilityExpr &CapE) {
197 unsigned n = FactIDs.size();
201 for (unsigned i = 0; i < n-1; ++i) {
202 if (FM[FactIDs[i]].matches(CapE)) {
203 FactIDs[i] = FactIDs[n-1];
208 if (FM[FactIDs[n-1]].matches(CapE)) {
215 iterator findLockIter(FactManager &FM, const CapabilityExpr &CapE) {
216 return std::find_if(begin(), end(), [&](FactID ID) {
217 return FM[ID].matches(CapE);
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);
225 return I != end() ? &FM[*I] : nullptr;
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);
232 return I != end() ? &FM[*I] : nullptr;
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);
240 return I != end() ? &FM[*I] : nullptr;
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;
251 class ThreadSafetyAnalyzer;
255 namespace threadSafety {
258 typedef SmallVector<const ValueDecl*, 4> BeforeVect;
261 BeforeInfo() : Vect(nullptr), Visited(false) { }
262 BeforeInfo(BeforeInfo &&O)
263 : Vect(std::move(O.Vect)), Visited(O.Visited)
266 std::unique_ptr<BeforeVect> Vect;
270 typedef llvm::DenseMap<const ValueDecl*, BeforeInfo> BeforeMap;
271 typedef llvm::DenseMap<const ValueDecl*, bool> CycleMap;
276 BeforeInfo* insertAttrExprs(const ValueDecl* Vd,
277 ThreadSafetyAnalyzer& Analyzer);
279 void checkBeforeAfter(const ValueDecl* Vd,
281 ThreadSafetyAnalyzer& Analyzer,
282 SourceLocation Loc, StringRef CapKind);
288 } // end namespace threadSafety
289 } // end namespace clang
292 typedef llvm::ImmutableMap<const NamedDecl*, unsigned> LocalVarContext;
293 class LocalVariableMap;
295 /// A side (entry or exit) of a CFG node.
296 enum CFGBlockSide { CBS_Entry, CBS_Exit };
298 /// CFGBlockInfo is a struct which contains all the information that is
299 /// maintained for each block in the CFG. See LocalVariableMap for more
300 /// information about the contexts.
301 struct CFGBlockInfo {
302 FactSet EntrySet; // Lockset held at entry to block
303 FactSet ExitSet; // Lockset held at exit from block
304 LocalVarContext EntryContext; // Context held at entry to block
305 LocalVarContext ExitContext; // Context held at exit from block
306 SourceLocation EntryLoc; // Location of first statement in block
307 SourceLocation ExitLoc; // Location of last statement in block.
308 unsigned EntryIndex; // Used to replay contexts later
309 bool Reachable; // Is this block reachable?
311 const FactSet &getSet(CFGBlockSide Side) const {
312 return Side == CBS_Entry ? EntrySet : ExitSet;
314 SourceLocation getLocation(CFGBlockSide Side) const {
315 return Side == CBS_Entry ? EntryLoc : ExitLoc;
319 CFGBlockInfo(LocalVarContext EmptyCtx)
320 : EntryContext(EmptyCtx), ExitContext(EmptyCtx), Reachable(false)
324 static CFGBlockInfo getEmptyBlockInfo(LocalVariableMap &M);
329 // A LocalVariableMap maintains a map from local variables to their currently
330 // valid definitions. It provides SSA-like functionality when traversing the
331 // CFG. Like SSA, each definition or assignment to a variable is assigned a
332 // unique name (an integer), which acts as the SSA name for that definition.
333 // The total set of names is shared among all CFG basic blocks.
334 // Unlike SSA, we do not rewrite expressions to replace local variables declrefs
335 // with their SSA-names. Instead, we compute a Context for each point in the
336 // code, which maps local variables to the appropriate SSA-name. This map
337 // changes with each assignment.
339 // The map is computed in a single pass over the CFG. Subsequent analyses can
340 // then query the map to find the appropriate Context for a statement, and use
341 // that Context to look up the definitions of variables.
342 class LocalVariableMap {
344 typedef LocalVarContext Context;
346 /// A VarDefinition consists of an expression, representing the value of the
347 /// variable, along with the context in which that expression should be
348 /// interpreted. A reference VarDefinition does not itself contain this
349 /// information, but instead contains a pointer to a previous VarDefinition.
350 struct VarDefinition {
352 friend class LocalVariableMap;
354 const NamedDecl *Dec; // The original declaration for this variable.
355 const Expr *Exp; // The expression for this variable, OR
356 unsigned Ref; // Reference to another VarDefinition
357 Context Ctx; // The map with which Exp should be interpreted.
359 bool isReference() { return !Exp; }
362 // Create ordinary variable definition
363 VarDefinition(const NamedDecl *D, const Expr *E, Context C)
364 : Dec(D), Exp(E), Ref(0), Ctx(C)
367 // Create reference to previous definition
368 VarDefinition(const NamedDecl *D, unsigned R, Context C)
369 : Dec(D), Exp(nullptr), Ref(R), Ctx(C)
374 Context::Factory ContextFactory;
375 std::vector<VarDefinition> VarDefinitions;
376 std::vector<unsigned> CtxIndices;
377 std::vector<std::pair<Stmt*, Context> > SavedContexts;
381 // index 0 is a placeholder for undefined variables (aka phi-nodes).
382 VarDefinitions.push_back(VarDefinition(nullptr, 0u, getEmptyContext()));
385 /// Look up a definition, within the given context.
386 const VarDefinition* lookup(const NamedDecl *D, Context Ctx) {
387 const unsigned *i = Ctx.lookup(D);
390 assert(*i < VarDefinitions.size());
391 return &VarDefinitions[*i];
394 /// Look up the definition for D within the given context. Returns
395 /// NULL if the expression is not statically known. If successful, also
396 /// modifies Ctx to hold the context of the return Expr.
397 const Expr* lookupExpr(const NamedDecl *D, Context &Ctx) {
398 const unsigned *P = Ctx.lookup(D);
404 if (VarDefinitions[i].Exp) {
405 Ctx = VarDefinitions[i].Ctx;
406 return VarDefinitions[i].Exp;
408 i = VarDefinitions[i].Ref;
413 Context getEmptyContext() { return ContextFactory.getEmptyMap(); }
415 /// Return the next context after processing S. This function is used by
416 /// clients of the class to get the appropriate context when traversing the
417 /// CFG. It must be called for every assignment or DeclStmt.
418 Context getNextContext(unsigned &CtxIndex, Stmt *S, Context C) {
419 if (SavedContexts[CtxIndex+1].first == S) {
421 Context Result = SavedContexts[CtxIndex].second;
427 void dumpVarDefinitionName(unsigned i) {
429 llvm::errs() << "Undefined";
432 const NamedDecl *Dec = VarDefinitions[i].Dec;
434 llvm::errs() << "<<NULL>>";
437 Dec->printName(llvm::errs());
438 llvm::errs() << "." << i << " " << ((const void*) Dec);
441 /// Dumps an ASCII representation of the variable map to llvm::errs()
443 for (unsigned i = 1, e = VarDefinitions.size(); i < e; ++i) {
444 const Expr *Exp = VarDefinitions[i].Exp;
445 unsigned Ref = VarDefinitions[i].Ref;
447 dumpVarDefinitionName(i);
448 llvm::errs() << " = ";
449 if (Exp) Exp->dump();
451 dumpVarDefinitionName(Ref);
452 llvm::errs() << "\n";
457 /// Dumps an ASCII representation of a Context to llvm::errs()
458 void dumpContext(Context C) {
459 for (Context::iterator I = C.begin(), E = C.end(); I != E; ++I) {
460 const NamedDecl *D = I.getKey();
461 D->printName(llvm::errs());
462 const unsigned *i = C.lookup(D);
463 llvm::errs() << " -> ";
464 dumpVarDefinitionName(*i);
465 llvm::errs() << "\n";
469 /// Builds the variable map.
470 void traverseCFG(CFG *CFGraph, const PostOrderCFGView *SortedGraph,
471 std::vector<CFGBlockInfo> &BlockInfo);
474 // Get the current context index
475 unsigned getContextIndex() { return SavedContexts.size()-1; }
477 // Save the current context for later replay
478 void saveContext(Stmt *S, Context C) {
479 SavedContexts.push_back(std::make_pair(S,C));
482 // Adds a new definition to the given context, and returns a new context.
483 // This method should be called when declaring a new variable.
484 Context addDefinition(const NamedDecl *D, const Expr *Exp, Context Ctx) {
485 assert(!Ctx.contains(D));
486 unsigned newID = VarDefinitions.size();
487 Context NewCtx = ContextFactory.add(Ctx, D, newID);
488 VarDefinitions.push_back(VarDefinition(D, Exp, Ctx));
492 // Add a new reference to an existing definition.
493 Context addReference(const NamedDecl *D, unsigned i, Context Ctx) {
494 unsigned newID = VarDefinitions.size();
495 Context NewCtx = ContextFactory.add(Ctx, D, newID);
496 VarDefinitions.push_back(VarDefinition(D, i, Ctx));
500 // Updates a definition only if that definition is already in the map.
501 // This method should be called when assigning to an existing variable.
502 Context updateDefinition(const NamedDecl *D, Expr *Exp, Context Ctx) {
503 if (Ctx.contains(D)) {
504 unsigned newID = VarDefinitions.size();
505 Context NewCtx = ContextFactory.remove(Ctx, D);
506 NewCtx = ContextFactory.add(NewCtx, D, newID);
507 VarDefinitions.push_back(VarDefinition(D, Exp, Ctx));
513 // Removes a definition from the context, but keeps the variable name
514 // as a valid variable. The index 0 is a placeholder for cleared definitions.
515 Context clearDefinition(const NamedDecl *D, Context Ctx) {
516 Context NewCtx = Ctx;
517 if (NewCtx.contains(D)) {
518 NewCtx = ContextFactory.remove(NewCtx, D);
519 NewCtx = ContextFactory.add(NewCtx, D, 0);
524 // Remove a definition entirely frmo the context.
525 Context removeDefinition(const NamedDecl *D, Context Ctx) {
526 Context NewCtx = Ctx;
527 if (NewCtx.contains(D)) {
528 NewCtx = ContextFactory.remove(NewCtx, D);
533 Context intersectContexts(Context C1, Context C2);
534 Context createReferenceContext(Context C);
535 void intersectBackEdge(Context C1, Context C2);
537 friend class VarMapBuilder;
541 // This has to be defined after LocalVariableMap.
542 CFGBlockInfo CFGBlockInfo::getEmptyBlockInfo(LocalVariableMap &M) {
543 return CFGBlockInfo(M.getEmptyContext());
547 /// Visitor which builds a LocalVariableMap
548 class VarMapBuilder : public StmtVisitor<VarMapBuilder> {
550 LocalVariableMap* VMap;
551 LocalVariableMap::Context Ctx;
553 VarMapBuilder(LocalVariableMap *VM, LocalVariableMap::Context C)
554 : VMap(VM), Ctx(C) {}
556 void VisitDeclStmt(DeclStmt *S);
557 void VisitBinaryOperator(BinaryOperator *BO);
561 // Add new local variables to the variable map
562 void VarMapBuilder::VisitDeclStmt(DeclStmt *S) {
563 bool modifiedCtx = false;
564 DeclGroupRef DGrp = S->getDeclGroup();
565 for (const auto *D : DGrp) {
566 if (const auto *VD = dyn_cast_or_null<VarDecl>(D)) {
567 const Expr *E = VD->getInit();
569 // Add local variables with trivial type to the variable map
570 QualType T = VD->getType();
571 if (T.isTrivialType(VD->getASTContext())) {
572 Ctx = VMap->addDefinition(VD, E, Ctx);
578 VMap->saveContext(S, Ctx);
581 // Update local variable definitions in variable map
582 void VarMapBuilder::VisitBinaryOperator(BinaryOperator *BO) {
583 if (!BO->isAssignmentOp())
586 Expr *LHSExp = BO->getLHS()->IgnoreParenCasts();
588 // Update the variable map and current context.
589 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(LHSExp)) {
590 ValueDecl *VDec = DRE->getDecl();
591 if (Ctx.lookup(VDec)) {
592 if (BO->getOpcode() == BO_Assign)
593 Ctx = VMap->updateDefinition(VDec, BO->getRHS(), Ctx);
595 // FIXME -- handle compound assignment operators
596 Ctx = VMap->clearDefinition(VDec, Ctx);
597 VMap->saveContext(BO, Ctx);
603 // Computes the intersection of two contexts. The intersection is the
604 // set of variables which have the same definition in both contexts;
605 // variables with different definitions are discarded.
606 LocalVariableMap::Context
607 LocalVariableMap::intersectContexts(Context C1, Context C2) {
609 for (const auto &P : C1) {
610 const NamedDecl *Dec = P.first;
611 const unsigned *i2 = C2.lookup(Dec);
612 if (!i2) // variable doesn't exist on second path
613 Result = removeDefinition(Dec, Result);
614 else if (*i2 != P.second) // variable exists, but has different definition
615 Result = clearDefinition(Dec, Result);
620 // For every variable in C, create a new variable that refers to the
621 // definition in C. Return a new context that contains these new variables.
622 // (We use this for a naive implementation of SSA on loop back-edges.)
623 LocalVariableMap::Context LocalVariableMap::createReferenceContext(Context C) {
624 Context Result = getEmptyContext();
625 for (const auto &P : C)
626 Result = addReference(P.first, P.second, Result);
630 // This routine also takes the intersection of C1 and C2, but it does so by
631 // altering the VarDefinitions. C1 must be the result of an earlier call to
632 // createReferenceContext.
633 void LocalVariableMap::intersectBackEdge(Context C1, Context C2) {
634 for (const auto &P : C1) {
635 unsigned i1 = P.second;
636 VarDefinition *VDef = &VarDefinitions[i1];
637 assert(VDef->isReference());
639 const unsigned *i2 = C2.lookup(P.first);
640 if (!i2 || (*i2 != i1))
641 VDef->Ref = 0; // Mark this variable as undefined
646 // Traverse the CFG in topological order, so all predecessors of a block
647 // (excluding back-edges) are visited before the block itself. At
648 // each point in the code, we calculate a Context, which holds the set of
649 // variable definitions which are visible at that point in execution.
650 // Visible variables are mapped to their definitions using an array that
651 // contains all definitions.
653 // At join points in the CFG, the set is computed as the intersection of
654 // the incoming sets along each edge, E.g.
656 // { Context | VarDefinitions }
657 // int x = 0; { x -> x1 | x1 = 0 }
658 // int y = 0; { x -> x1, y -> y1 | y1 = 0, x1 = 0 }
659 // if (b) x = 1; { x -> x2, y -> y1 | x2 = 1, y1 = 0, ... }
660 // else x = 2; { x -> x3, y -> y1 | x3 = 2, x2 = 1, ... }
661 // ... { y -> y1 (x is unknown) | x3 = 2, x2 = 1, ... }
663 // This is essentially a simpler and more naive version of the standard SSA
664 // algorithm. Those definitions that remain in the intersection are from blocks
665 // that strictly dominate the current block. We do not bother to insert proper
666 // phi nodes, because they are not used in our analysis; instead, wherever
667 // a phi node would be required, we simply remove that definition from the
668 // context (E.g. x above).
670 // The initial traversal does not capture back-edges, so those need to be
671 // handled on a separate pass. Whenever the first pass encounters an
672 // incoming back edge, it duplicates the context, creating new definitions
673 // that refer back to the originals. (These correspond to places where SSA
674 // might have to insert a phi node.) On the second pass, these definitions are
675 // set to NULL if the variable has changed on the back-edge (i.e. a phi
676 // node was actually required.) E.g.
678 // { Context | VarDefinitions }
679 // int x = 0, y = 0; { x -> x1, y -> y1 | y1 = 0, x1 = 0 }
680 // while (b) { x -> x2, y -> y1 | [1st:] x2=x1; [2nd:] x2=NULL; }
681 // x = x+1; { x -> x3, y -> y1 | x3 = x2 + 1, ... }
682 // ... { y -> y1 | x3 = 2, x2 = 1, ... }
684 void LocalVariableMap::traverseCFG(CFG *CFGraph,
685 const PostOrderCFGView *SortedGraph,
686 std::vector<CFGBlockInfo> &BlockInfo) {
687 PostOrderCFGView::CFGBlockSet VisitedBlocks(CFGraph);
689 CtxIndices.resize(CFGraph->getNumBlockIDs());
691 for (const auto *CurrBlock : *SortedGraph) {
692 int CurrBlockID = CurrBlock->getBlockID();
693 CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlockID];
695 VisitedBlocks.insert(CurrBlock);
697 // Calculate the entry context for the current block
698 bool HasBackEdges = false;
700 for (CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
701 PE = CurrBlock->pred_end(); PI != PE; ++PI) {
702 // if *PI -> CurrBlock is a back edge, so skip it
703 if (*PI == nullptr || !VisitedBlocks.alreadySet(*PI)) {
708 int PrevBlockID = (*PI)->getBlockID();
709 CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
712 CurrBlockInfo->EntryContext = PrevBlockInfo->ExitContext;
716 CurrBlockInfo->EntryContext =
717 intersectContexts(CurrBlockInfo->EntryContext,
718 PrevBlockInfo->ExitContext);
722 // Duplicate the context if we have back-edges, so we can call
723 // intersectBackEdges later.
725 CurrBlockInfo->EntryContext =
726 createReferenceContext(CurrBlockInfo->EntryContext);
728 // Create a starting context index for the current block
729 saveContext(nullptr, CurrBlockInfo->EntryContext);
730 CurrBlockInfo->EntryIndex = getContextIndex();
732 // Visit all the statements in the basic block.
733 VarMapBuilder VMapBuilder(this, CurrBlockInfo->EntryContext);
734 for (CFGBlock::const_iterator BI = CurrBlock->begin(),
735 BE = CurrBlock->end(); BI != BE; ++BI) {
736 switch (BI->getKind()) {
737 case CFGElement::Statement: {
738 CFGStmt CS = BI->castAs<CFGStmt>();
739 VMapBuilder.Visit(const_cast<Stmt*>(CS.getStmt()));
746 CurrBlockInfo->ExitContext = VMapBuilder.Ctx;
748 // Mark variables on back edges as "unknown" if they've been changed.
749 for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
750 SE = CurrBlock->succ_end(); SI != SE; ++SI) {
751 // if CurrBlock -> *SI is *not* a back edge
752 if (*SI == nullptr || !VisitedBlocks.alreadySet(*SI))
755 CFGBlock *FirstLoopBlock = *SI;
756 Context LoopBegin = BlockInfo[FirstLoopBlock->getBlockID()].EntryContext;
757 Context LoopEnd = CurrBlockInfo->ExitContext;
758 intersectBackEdge(LoopBegin, LoopEnd);
762 // Put an extra entry at the end of the indexed context array
763 unsigned exitID = CFGraph->getExit().getBlockID();
764 saveContext(nullptr, BlockInfo[exitID].ExitContext);
767 /// Find the appropriate source locations to use when producing diagnostics for
768 /// each block in the CFG.
769 static void findBlockLocations(CFG *CFGraph,
770 const PostOrderCFGView *SortedGraph,
771 std::vector<CFGBlockInfo> &BlockInfo) {
772 for (const auto *CurrBlock : *SortedGraph) {
773 CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlock->getBlockID()];
775 // Find the source location of the last statement in the block, if the
776 // block is not empty.
777 if (const Stmt *S = CurrBlock->getTerminator()) {
778 CurrBlockInfo->EntryLoc = CurrBlockInfo->ExitLoc = S->getLocStart();
780 for (CFGBlock::const_reverse_iterator BI = CurrBlock->rbegin(),
781 BE = CurrBlock->rend(); BI != BE; ++BI) {
782 // FIXME: Handle other CFGElement kinds.
783 if (Optional<CFGStmt> CS = BI->getAs<CFGStmt>()) {
784 CurrBlockInfo->ExitLoc = CS->getStmt()->getLocStart();
790 if (!CurrBlockInfo->ExitLoc.isInvalid()) {
791 // This block contains at least one statement. Find the source location
792 // of the first statement in the block.
793 for (CFGBlock::const_iterator BI = CurrBlock->begin(),
794 BE = CurrBlock->end(); BI != BE; ++BI) {
795 // FIXME: Handle other CFGElement kinds.
796 if (Optional<CFGStmt> CS = BI->getAs<CFGStmt>()) {
797 CurrBlockInfo->EntryLoc = CS->getStmt()->getLocStart();
801 } else if (CurrBlock->pred_size() == 1 && *CurrBlock->pred_begin() &&
802 CurrBlock != &CFGraph->getExit()) {
803 // The block is empty, and has a single predecessor. Use its exit
805 CurrBlockInfo->EntryLoc = CurrBlockInfo->ExitLoc =
806 BlockInfo[(*CurrBlock->pred_begin())->getBlockID()].ExitLoc;
811 class LockableFactEntry : public FactEntry {
813 bool Managed; ///< managed by ScopedLockable object
816 LockableFactEntry(const CapabilityExpr &CE, LockKind LK, SourceLocation Loc,
817 bool Mng = false, bool Asrt = false)
818 : FactEntry(CE, LK, Loc, Asrt), Managed(Mng) {}
821 handleRemovalFromIntersection(const FactSet &FSet, FactManager &FactMan,
822 SourceLocation JoinLoc, LockErrorKind LEK,
823 ThreadSafetyHandler &Handler) const override {
824 if (!Managed && !asserted() && !negative() && !isUniversal()) {
825 Handler.handleMutexHeldEndOfScope("mutex", toString(), loc(), JoinLoc,
830 void handleUnlock(FactSet &FSet, FactManager &FactMan,
831 const CapabilityExpr &Cp, SourceLocation UnlockLoc,
832 bool FullyRemove, ThreadSafetyHandler &Handler,
833 StringRef DiagKind) const override {
834 FSet.removeLock(FactMan, Cp);
835 if (!Cp.negative()) {
836 FSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
837 !Cp, LK_Exclusive, UnlockLoc));
842 class ScopedLockableFactEntry : public FactEntry {
844 SmallVector<const til::SExpr *, 4> UnderlyingMutexes;
847 ScopedLockableFactEntry(const CapabilityExpr &CE, SourceLocation Loc,
848 const CapExprSet &Excl, const CapExprSet &Shrd)
849 : FactEntry(CE, LK_Exclusive, Loc, false) {
850 for (const auto &M : Excl)
851 UnderlyingMutexes.push_back(M.sexpr());
852 for (const auto &M : Shrd)
853 UnderlyingMutexes.push_back(M.sexpr());
857 handleRemovalFromIntersection(const FactSet &FSet, FactManager &FactMan,
858 SourceLocation JoinLoc, LockErrorKind LEK,
859 ThreadSafetyHandler &Handler) const override {
860 for (const til::SExpr *UnderlyingMutex : UnderlyingMutexes) {
861 if (FSet.findLock(FactMan, CapabilityExpr(UnderlyingMutex, false))) {
862 // If this scoped lock manages another mutex, and if the underlying
863 // mutex is still held, then warn about the underlying mutex.
864 Handler.handleMutexHeldEndOfScope(
865 "mutex", sx::toString(UnderlyingMutex), loc(), JoinLoc, LEK);
870 void handleUnlock(FactSet &FSet, FactManager &FactMan,
871 const CapabilityExpr &Cp, SourceLocation UnlockLoc,
872 bool FullyRemove, ThreadSafetyHandler &Handler,
873 StringRef DiagKind) const override {
874 assert(!Cp.negative() && "Managing object cannot be negative.");
875 for (const til::SExpr *UnderlyingMutex : UnderlyingMutexes) {
876 CapabilityExpr UnderCp(UnderlyingMutex, false);
877 auto UnderEntry = llvm::make_unique<LockableFactEntry>(
878 !UnderCp, LK_Exclusive, UnlockLoc);
881 // We're destroying the managing object.
882 // Remove the underlying mutex if it exists; but don't warn.
883 if (FSet.findLock(FactMan, UnderCp)) {
884 FSet.removeLock(FactMan, UnderCp);
885 FSet.addLock(FactMan, std::move(UnderEntry));
888 // We're releasing the underlying mutex, but not destroying the
889 // managing object. Warn on dual release.
890 if (!FSet.findLock(FactMan, UnderCp)) {
891 Handler.handleUnmatchedUnlock(DiagKind, UnderCp.toString(),
894 FSet.removeLock(FactMan, UnderCp);
895 FSet.addLock(FactMan, std::move(UnderEntry));
899 FSet.removeLock(FactMan, Cp);
903 /// \brief Class which implements the core thread safety analysis routines.
904 class ThreadSafetyAnalyzer {
905 friend class BuildLockset;
906 friend class threadSafety::BeforeSet;
908 llvm::BumpPtrAllocator Bpa;
909 threadSafety::til::MemRegionRef Arena;
910 threadSafety::SExprBuilder SxBuilder;
912 ThreadSafetyHandler &Handler;
913 const CXXMethodDecl *CurrentMethod;
914 LocalVariableMap LocalVarMap;
916 std::vector<CFGBlockInfo> BlockInfo;
918 BeforeSet* GlobalBeforeSet;
921 ThreadSafetyAnalyzer(ThreadSafetyHandler &H, BeforeSet* Bset)
922 : Arena(&Bpa), SxBuilder(Arena), Handler(H), GlobalBeforeSet(Bset) {}
924 bool inCurrentScope(const CapabilityExpr &CapE);
926 void addLock(FactSet &FSet, std::unique_ptr<FactEntry> Entry,
927 StringRef DiagKind, bool ReqAttr = false);
928 void removeLock(FactSet &FSet, const CapabilityExpr &CapE,
929 SourceLocation UnlockLoc, bool FullyRemove, LockKind Kind,
932 template <typename AttrType>
933 void getMutexIDs(CapExprSet &Mtxs, AttrType *Attr, Expr *Exp,
934 const NamedDecl *D, VarDecl *SelfDecl = nullptr);
936 template <class AttrType>
937 void getMutexIDs(CapExprSet &Mtxs, AttrType *Attr, Expr *Exp,
939 const CFGBlock *PredBlock, const CFGBlock *CurrBlock,
940 Expr *BrE, bool Neg);
942 const CallExpr* getTrylockCallExpr(const Stmt *Cond, LocalVarContext C,
945 void getEdgeLockset(FactSet &Result, const FactSet &ExitSet,
946 const CFGBlock* PredBlock,
947 const CFGBlock *CurrBlock);
949 void intersectAndWarn(FactSet &FSet1, const FactSet &FSet2,
950 SourceLocation JoinLoc,
951 LockErrorKind LEK1, LockErrorKind LEK2,
954 void intersectAndWarn(FactSet &FSet1, const FactSet &FSet2,
955 SourceLocation JoinLoc, LockErrorKind LEK1,
957 intersectAndWarn(FSet1, FSet2, JoinLoc, LEK1, LEK1, Modify);
960 void runAnalysis(AnalysisDeclContext &AC);
964 /// Process acquired_before and acquired_after attributes on Vd.
965 BeforeSet::BeforeInfo* BeforeSet::insertAttrExprs(const ValueDecl* Vd,
966 ThreadSafetyAnalyzer& Analyzer) {
967 // Create a new entry for Vd.
968 auto& Entry = BMap.FindAndConstruct(Vd);
969 BeforeInfo* Info = &Entry.second;
970 BeforeVect* Bv = nullptr;
972 for (Attr* At : Vd->attrs()) {
973 switch (At->getKind()) {
974 case attr::AcquiredBefore: {
975 auto *A = cast<AcquiredBeforeAttr>(At);
977 // Create a new BeforeVect for Vd if necessary.
980 Info->Vect.reset(Bv);
982 // Read exprs from the attribute, and add them to BeforeVect.
983 for (const auto *Arg : A->args()) {
985 Analyzer.SxBuilder.translateAttrExpr(Arg, nullptr);
986 if (const ValueDecl *Cpvd = Cp.valueDecl()) {
988 auto It = BMap.find(Cpvd);
989 if (It == BMap.end())
990 insertAttrExprs(Cpvd, Analyzer);
995 case attr::AcquiredAfter: {
996 auto *A = cast<AcquiredAfterAttr>(At);
998 // Read exprs from the attribute, and add them to BeforeVect.
999 for (const auto *Arg : A->args()) {
1001 Analyzer.SxBuilder.translateAttrExpr(Arg, nullptr);
1002 if (const ValueDecl *ArgVd = Cp.valueDecl()) {
1003 // Get entry for mutex listed in attribute
1004 BeforeInfo* ArgInfo;
1005 auto It = BMap.find(ArgVd);
1006 if (It == BMap.end())
1007 ArgInfo = insertAttrExprs(ArgVd, Analyzer);
1009 ArgInfo = &It->second;
1011 // Create a new BeforeVect if necessary.
1012 BeforeVect* ArgBv = ArgInfo->Vect.get();
1014 ArgBv = new BeforeVect;
1015 ArgInfo->Vect.reset(ArgBv);
1017 ArgBv->push_back(Vd);
1031 /// Return true if any mutexes in FSet are in the acquired_before set of Vd.
1032 void BeforeSet::checkBeforeAfter(const ValueDecl* StartVd,
1033 const FactSet& FSet,
1034 ThreadSafetyAnalyzer& Analyzer,
1035 SourceLocation Loc, StringRef CapKind) {
1036 SmallVector<BeforeInfo*, 8> InfoVect;
1038 // Do a depth-first traversal of Vd.
1039 // Return true if there are cycles.
1040 std::function<bool (const ValueDecl*)> traverse = [&](const ValueDecl* Vd) {
1044 BeforeSet::BeforeInfo* Info;
1045 auto It = BMap.find(Vd);
1046 if (It == BMap.end())
1047 Info = insertAttrExprs(Vd, Analyzer);
1051 if (Info->Visited == 1)
1054 if (Info->Visited == 2)
1057 BeforeVect* Bv = Info->Vect.get();
1061 InfoVect.push_back(Info);
1063 for (auto *Vdb : *Bv) {
1064 // Exclude mutexes in our immediate before set.
1065 if (FSet.containsMutexDecl(Analyzer.FactMan, Vdb)) {
1066 StringRef L1 = StartVd->getName();
1067 StringRef L2 = Vdb->getName();
1068 Analyzer.Handler.handleLockAcquiredBefore(CapKind, L1, L2, Loc);
1070 // Transitively search other before sets, and warn on cycles.
1071 if (traverse(Vdb)) {
1072 if (CycMap.find(Vd) == CycMap.end()) {
1073 CycMap.insert(std::make_pair(Vd, true));
1074 StringRef L1 = Vd->getName();
1075 Analyzer.Handler.handleBeforeAfterCycle(L1, Vd->getLocation());
1085 for (auto* Info : InfoVect)
1091 /// \brief Gets the value decl pointer from DeclRefExprs or MemberExprs.
1092 static const ValueDecl *getValueDecl(const Expr *Exp) {
1093 if (const auto *CE = dyn_cast<ImplicitCastExpr>(Exp))
1094 return getValueDecl(CE->getSubExpr());
1096 if (const auto *DR = dyn_cast<DeclRefExpr>(Exp))
1097 return DR->getDecl();
1099 if (const auto *ME = dyn_cast<MemberExpr>(Exp))
1100 return ME->getMemberDecl();
1106 template <typename Ty>
1107 class has_arg_iterator_range {
1108 typedef char yes[1];
1111 template <typename Inner>
1112 static yes& test(Inner *I, decltype(I->args()) * = nullptr);
1115 static no& test(...);
1118 static const bool value = sizeof(test<Ty>(nullptr)) == sizeof(yes);
1122 static StringRef ClassifyDiagnostic(const CapabilityAttr *A) {
1123 return A->getName();
1126 static StringRef ClassifyDiagnostic(QualType VDT) {
1127 // We need to look at the declaration of the type of the value to determine
1128 // which it is. The type should either be a record or a typedef, or a pointer
1129 // or reference thereof.
1130 if (const auto *RT = VDT->getAs<RecordType>()) {
1131 if (const auto *RD = RT->getDecl())
1132 if (const auto *CA = RD->getAttr<CapabilityAttr>())
1133 return ClassifyDiagnostic(CA);
1134 } else if (const auto *TT = VDT->getAs<TypedefType>()) {
1135 if (const auto *TD = TT->getDecl())
1136 if (const auto *CA = TD->getAttr<CapabilityAttr>())
1137 return ClassifyDiagnostic(CA);
1138 } else if (VDT->isPointerType() || VDT->isReferenceType())
1139 return ClassifyDiagnostic(VDT->getPointeeType());
1144 static StringRef ClassifyDiagnostic(const ValueDecl *VD) {
1145 assert(VD && "No ValueDecl passed");
1147 // The ValueDecl is the declaration of a mutex or role (hopefully).
1148 return ClassifyDiagnostic(VD->getType());
1151 template <typename AttrTy>
1152 static typename std::enable_if<!has_arg_iterator_range<AttrTy>::value,
1154 ClassifyDiagnostic(const AttrTy *A) {
1155 if (const ValueDecl *VD = getValueDecl(A->getArg()))
1156 return ClassifyDiagnostic(VD);
1160 template <typename AttrTy>
1161 static typename std::enable_if<has_arg_iterator_range<AttrTy>::value,
1163 ClassifyDiagnostic(const AttrTy *A) {
1164 for (const auto *Arg : A->args()) {
1165 if (const ValueDecl *VD = getValueDecl(Arg))
1166 return ClassifyDiagnostic(VD);
1172 inline bool ThreadSafetyAnalyzer::inCurrentScope(const CapabilityExpr &CapE) {
1175 if (auto *P = dyn_cast_or_null<til::Project>(CapE.sexpr())) {
1176 auto *VD = P->clangDecl();
1178 return VD->getDeclContext() == CurrentMethod->getDeclContext();
1184 /// \brief Add a new lock to the lockset, warning if the lock is already there.
1185 /// \param ReqAttr -- true if this is part of an initial Requires attribute.
1186 void ThreadSafetyAnalyzer::addLock(FactSet &FSet,
1187 std::unique_ptr<FactEntry> Entry,
1188 StringRef DiagKind, bool ReqAttr) {
1189 if (Entry->shouldIgnore())
1192 if (!ReqAttr && !Entry->negative()) {
1193 // look for the negative capability, and remove it from the fact set.
1194 CapabilityExpr NegC = !*Entry;
1195 FactEntry *Nen = FSet.findLock(FactMan, NegC);
1197 FSet.removeLock(FactMan, NegC);
1200 if (inCurrentScope(*Entry) && !Entry->asserted())
1201 Handler.handleNegativeNotHeld(DiagKind, Entry->toString(),
1202 NegC.toString(), Entry->loc());
1206 // Check before/after constraints
1207 if (Handler.issueBetaWarnings() &&
1208 !Entry->asserted() && !Entry->declared()) {
1209 GlobalBeforeSet->checkBeforeAfter(Entry->valueDecl(), FSet, *this,
1210 Entry->loc(), DiagKind);
1213 // FIXME: Don't always warn when we have support for reentrant locks.
1214 if (FSet.findLock(FactMan, *Entry)) {
1215 if (!Entry->asserted())
1216 Handler.handleDoubleLock(DiagKind, Entry->toString(), Entry->loc());
1218 FSet.addLock(FactMan, std::move(Entry));
1223 /// \brief Remove a lock from the lockset, warning if the lock is not there.
1224 /// \param UnlockLoc The source location of the unlock (only used in error msg)
1225 void ThreadSafetyAnalyzer::removeLock(FactSet &FSet, const CapabilityExpr &Cp,
1226 SourceLocation UnlockLoc,
1227 bool FullyRemove, LockKind ReceivedKind,
1228 StringRef DiagKind) {
1229 if (Cp.shouldIgnore())
1232 const FactEntry *LDat = FSet.findLock(FactMan, Cp);
1234 Handler.handleUnmatchedUnlock(DiagKind, Cp.toString(), UnlockLoc);
1238 // Generic lock removal doesn't care about lock kind mismatches, but
1239 // otherwise diagnose when the lock kinds are mismatched.
1240 if (ReceivedKind != LK_Generic && LDat->kind() != ReceivedKind) {
1241 Handler.handleIncorrectUnlockKind(DiagKind, Cp.toString(),
1242 LDat->kind(), ReceivedKind, UnlockLoc);
1245 LDat->handleUnlock(FSet, FactMan, Cp, UnlockLoc, FullyRemove, Handler,
1250 /// \brief Extract the list of mutexIDs from the attribute on an expression,
1251 /// and push them onto Mtxs, discarding any duplicates.
1252 template <typename AttrType>
1253 void ThreadSafetyAnalyzer::getMutexIDs(CapExprSet &Mtxs, AttrType *Attr,
1254 Expr *Exp, const NamedDecl *D,
1255 VarDecl *SelfDecl) {
1256 if (Attr->args_size() == 0) {
1257 // The mutex held is the "this" object.
1258 CapabilityExpr Cp = SxBuilder.translateAttrExpr(nullptr, D, Exp, SelfDecl);
1259 if (Cp.isInvalid()) {
1260 warnInvalidLock(Handler, nullptr, D, Exp, ClassifyDiagnostic(Attr));
1264 if (!Cp.shouldIgnore())
1265 Mtxs.push_back_nodup(Cp);
1269 for (const auto *Arg : Attr->args()) {
1270 CapabilityExpr Cp = SxBuilder.translateAttrExpr(Arg, D, Exp, SelfDecl);
1271 if (Cp.isInvalid()) {
1272 warnInvalidLock(Handler, nullptr, D, Exp, ClassifyDiagnostic(Attr));
1276 if (!Cp.shouldIgnore())
1277 Mtxs.push_back_nodup(Cp);
1282 /// \brief Extract the list of mutexIDs from a trylock attribute. If the
1283 /// trylock applies to the given edge, then push them onto Mtxs, discarding
1285 template <class AttrType>
1286 void ThreadSafetyAnalyzer::getMutexIDs(CapExprSet &Mtxs, AttrType *Attr,
1287 Expr *Exp, const NamedDecl *D,
1288 const CFGBlock *PredBlock,
1289 const CFGBlock *CurrBlock,
1290 Expr *BrE, bool Neg) {
1291 // Find out which branch has the lock
1292 bool branch = false;
1293 if (CXXBoolLiteralExpr *BLE = dyn_cast_or_null<CXXBoolLiteralExpr>(BrE))
1294 branch = BLE->getValue();
1295 else if (IntegerLiteral *ILE = dyn_cast_or_null<IntegerLiteral>(BrE))
1296 branch = ILE->getValue().getBoolValue();
1298 int branchnum = branch ? 0 : 1;
1300 branchnum = !branchnum;
1302 // If we've taken the trylock branch, then add the lock
1304 for (CFGBlock::const_succ_iterator SI = PredBlock->succ_begin(),
1305 SE = PredBlock->succ_end(); SI != SE && i < 2; ++SI, ++i) {
1306 if (*SI == CurrBlock && i == branchnum)
1307 getMutexIDs(Mtxs, Attr, Exp, D);
1311 static bool getStaticBooleanValue(Expr *E, bool &TCond) {
1312 if (isa<CXXNullPtrLiteralExpr>(E) || isa<GNUNullExpr>(E)) {
1315 } else if (CXXBoolLiteralExpr *BLE = dyn_cast<CXXBoolLiteralExpr>(E)) {
1316 TCond = BLE->getValue();
1318 } else if (IntegerLiteral *ILE = dyn_cast<IntegerLiteral>(E)) {
1319 TCond = ILE->getValue().getBoolValue();
1321 } else if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
1322 return getStaticBooleanValue(CE->getSubExpr(), TCond);
1328 // If Cond can be traced back to a function call, return the call expression.
1329 // The negate variable should be called with false, and will be set to true
1330 // if the function call is negated, e.g. if (!mu.tryLock(...))
1331 const CallExpr* ThreadSafetyAnalyzer::getTrylockCallExpr(const Stmt *Cond,
1337 if (const CallExpr *CallExp = dyn_cast<CallExpr>(Cond)) {
1340 else if (const ParenExpr *PE = dyn_cast<ParenExpr>(Cond)) {
1341 return getTrylockCallExpr(PE->getSubExpr(), C, Negate);
1343 else if (const ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(Cond)) {
1344 return getTrylockCallExpr(CE->getSubExpr(), C, Negate);
1346 else if (const ExprWithCleanups* EWC = dyn_cast<ExprWithCleanups>(Cond)) {
1347 return getTrylockCallExpr(EWC->getSubExpr(), C, Negate);
1349 else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Cond)) {
1350 const Expr *E = LocalVarMap.lookupExpr(DRE->getDecl(), C);
1351 return getTrylockCallExpr(E, C, Negate);
1353 else if (const UnaryOperator *UOP = dyn_cast<UnaryOperator>(Cond)) {
1354 if (UOP->getOpcode() == UO_LNot) {
1356 return getTrylockCallExpr(UOP->getSubExpr(), C, Negate);
1360 else if (const BinaryOperator *BOP = dyn_cast<BinaryOperator>(Cond)) {
1361 if (BOP->getOpcode() == BO_EQ || BOP->getOpcode() == BO_NE) {
1362 if (BOP->getOpcode() == BO_NE)
1366 if (getStaticBooleanValue(BOP->getRHS(), TCond)) {
1367 if (!TCond) Negate = !Negate;
1368 return getTrylockCallExpr(BOP->getLHS(), C, Negate);
1371 if (getStaticBooleanValue(BOP->getLHS(), TCond)) {
1372 if (!TCond) Negate = !Negate;
1373 return getTrylockCallExpr(BOP->getRHS(), C, Negate);
1377 if (BOP->getOpcode() == BO_LAnd) {
1378 // LHS must have been evaluated in a different block.
1379 return getTrylockCallExpr(BOP->getRHS(), C, Negate);
1381 if (BOP->getOpcode() == BO_LOr) {
1382 return getTrylockCallExpr(BOP->getRHS(), C, Negate);
1390 /// \brief Find the lockset that holds on the edge between PredBlock
1391 /// and CurrBlock. The edge set is the exit set of PredBlock (passed
1392 /// as the ExitSet parameter) plus any trylocks, which are conditionally held.
1393 void ThreadSafetyAnalyzer::getEdgeLockset(FactSet& Result,
1394 const FactSet &ExitSet,
1395 const CFGBlock *PredBlock,
1396 const CFGBlock *CurrBlock) {
1399 const Stmt *Cond = PredBlock->getTerminatorCondition();
1403 bool Negate = false;
1404 const CFGBlockInfo *PredBlockInfo = &BlockInfo[PredBlock->getBlockID()];
1405 const LocalVarContext &LVarCtx = PredBlockInfo->ExitContext;
1406 StringRef CapDiagKind = "mutex";
1409 const_cast<CallExpr*>(getTrylockCallExpr(Cond, LVarCtx, Negate));
1413 NamedDecl *FunDecl = dyn_cast_or_null<NamedDecl>(Exp->getCalleeDecl());
1414 if(!FunDecl || !FunDecl->hasAttrs())
1417 CapExprSet ExclusiveLocksToAdd;
1418 CapExprSet SharedLocksToAdd;
1420 // If the condition is a call to a Trylock function, then grab the attributes
1421 for (auto *Attr : FunDecl->attrs()) {
1422 switch (Attr->getKind()) {
1423 case attr::ExclusiveTrylockFunction: {
1424 ExclusiveTrylockFunctionAttr *A =
1425 cast<ExclusiveTrylockFunctionAttr>(Attr);
1426 getMutexIDs(ExclusiveLocksToAdd, A, Exp, FunDecl,
1427 PredBlock, CurrBlock, A->getSuccessValue(), Negate);
1428 CapDiagKind = ClassifyDiagnostic(A);
1431 case attr::SharedTrylockFunction: {
1432 SharedTrylockFunctionAttr *A =
1433 cast<SharedTrylockFunctionAttr>(Attr);
1434 getMutexIDs(SharedLocksToAdd, A, Exp, FunDecl,
1435 PredBlock, CurrBlock, A->getSuccessValue(), Negate);
1436 CapDiagKind = ClassifyDiagnostic(A);
1444 // Add and remove locks.
1445 SourceLocation Loc = Exp->getExprLoc();
1446 for (const auto &ExclusiveLockToAdd : ExclusiveLocksToAdd)
1447 addLock(Result, llvm::make_unique<LockableFactEntry>(ExclusiveLockToAdd,
1450 for (const auto &SharedLockToAdd : SharedLocksToAdd)
1451 addLock(Result, llvm::make_unique<LockableFactEntry>(SharedLockToAdd,
1457 /// \brief We use this class to visit different types of expressions in
1458 /// CFGBlocks, and build up the lockset.
1459 /// An expression may cause us to add or remove locks from the lockset, or else
1460 /// output error messages related to missing locks.
1461 /// FIXME: In future, we may be able to not inherit from a visitor.
1462 class BuildLockset : public StmtVisitor<BuildLockset> {
1463 friend class ThreadSafetyAnalyzer;
1465 ThreadSafetyAnalyzer *Analyzer;
1467 LocalVariableMap::Context LVarCtx;
1471 void warnIfMutexNotHeld(const NamedDecl *D, const Expr *Exp, AccessKind AK,
1472 Expr *MutexExp, ProtectedOperationKind POK,
1473 StringRef DiagKind, SourceLocation Loc);
1474 void warnIfMutexHeld(const NamedDecl *D, const Expr *Exp, Expr *MutexExp,
1475 StringRef DiagKind);
1477 void checkAccess(const Expr *Exp, AccessKind AK,
1478 ProtectedOperationKind POK = POK_VarAccess);
1479 void checkPtAccess(const Expr *Exp, AccessKind AK,
1480 ProtectedOperationKind POK = POK_VarAccess);
1482 void handleCall(Expr *Exp, const NamedDecl *D, VarDecl *VD = nullptr);
1485 BuildLockset(ThreadSafetyAnalyzer *Anlzr, CFGBlockInfo &Info)
1486 : StmtVisitor<BuildLockset>(),
1488 FSet(Info.EntrySet),
1489 LVarCtx(Info.EntryContext),
1490 CtxIndex(Info.EntryIndex)
1493 void VisitUnaryOperator(UnaryOperator *UO);
1494 void VisitBinaryOperator(BinaryOperator *BO);
1495 void VisitCastExpr(CastExpr *CE);
1496 void VisitCallExpr(CallExpr *Exp);
1497 void VisitCXXConstructExpr(CXXConstructExpr *Exp);
1498 void VisitDeclStmt(DeclStmt *S);
1502 /// \brief Warn if the LSet does not contain a lock sufficient to protect access
1503 /// of at least the passed in AccessKind.
1504 void BuildLockset::warnIfMutexNotHeld(const NamedDecl *D, const Expr *Exp,
1505 AccessKind AK, Expr *MutexExp,
1506 ProtectedOperationKind POK,
1507 StringRef DiagKind, SourceLocation Loc) {
1508 LockKind LK = getLockKindFromAccessKind(AK);
1510 CapabilityExpr Cp = Analyzer->SxBuilder.translateAttrExpr(MutexExp, D, Exp);
1511 if (Cp.isInvalid()) {
1512 warnInvalidLock(Analyzer->Handler, MutexExp, D, Exp, DiagKind);
1514 } else if (Cp.shouldIgnore()) {
1518 if (Cp.negative()) {
1519 // Negative capabilities act like locks excluded
1520 FactEntry *LDat = FSet.findLock(Analyzer->FactMan, !Cp);
1522 Analyzer->Handler.handleFunExcludesLock(
1523 DiagKind, D->getNameAsString(), (!Cp).toString(), Loc);
1527 // If this does not refer to a negative capability in the same class,
1529 if (!Analyzer->inCurrentScope(Cp))
1532 // Otherwise the negative requirement must be propagated to the caller.
1533 LDat = FSet.findLock(Analyzer->FactMan, Cp);
1535 Analyzer->Handler.handleMutexNotHeld("", D, POK, Cp.toString(),
1541 FactEntry* LDat = FSet.findLockUniv(Analyzer->FactMan, Cp);
1542 bool NoError = true;
1544 // No exact match found. Look for a partial match.
1545 LDat = FSet.findPartialMatch(Analyzer->FactMan, Cp);
1547 // Warn that there's no precise match.
1548 std::string PartMatchStr = LDat->toString();
1549 StringRef PartMatchName(PartMatchStr);
1550 Analyzer->Handler.handleMutexNotHeld(DiagKind, D, POK, Cp.toString(),
1551 LK, Loc, &PartMatchName);
1553 // Warn that there's no match at all.
1554 Analyzer->Handler.handleMutexNotHeld(DiagKind, D, POK, Cp.toString(),
1559 // Make sure the mutex we found is the right kind.
1560 if (NoError && LDat && !LDat->isAtLeast(LK)) {
1561 Analyzer->Handler.handleMutexNotHeld(DiagKind, D, POK, Cp.toString(),
1566 /// \brief Warn if the LSet contains the given lock.
1567 void BuildLockset::warnIfMutexHeld(const NamedDecl *D, const Expr *Exp,
1568 Expr *MutexExp, StringRef DiagKind) {
1569 CapabilityExpr Cp = Analyzer->SxBuilder.translateAttrExpr(MutexExp, D, Exp);
1570 if (Cp.isInvalid()) {
1571 warnInvalidLock(Analyzer->Handler, MutexExp, D, Exp, DiagKind);
1573 } else if (Cp.shouldIgnore()) {
1577 FactEntry* LDat = FSet.findLock(Analyzer->FactMan, Cp);
1579 Analyzer->Handler.handleFunExcludesLock(
1580 DiagKind, D->getNameAsString(), Cp.toString(), Exp->getExprLoc());
1584 /// \brief Checks guarded_by and pt_guarded_by attributes.
1585 /// Whenever we identify an access (read or write) to a DeclRefExpr that is
1586 /// marked with guarded_by, we must ensure the appropriate mutexes are held.
1587 /// Similarly, we check if the access is to an expression that dereferences
1588 /// a pointer marked with pt_guarded_by.
1589 void BuildLockset::checkAccess(const Expr *Exp, AccessKind AK,
1590 ProtectedOperationKind POK) {
1591 Exp = Exp->IgnoreParenCasts();
1593 SourceLocation Loc = Exp->getExprLoc();
1595 // Local variables of reference type cannot be re-assigned;
1596 // map them to their initializer.
1597 while (const auto *DRE = dyn_cast<DeclRefExpr>(Exp)) {
1598 const auto *VD = dyn_cast<VarDecl>(DRE->getDecl()->getCanonicalDecl());
1599 if (VD && VD->isLocalVarDecl() && VD->getType()->isReferenceType()) {
1600 if (const auto *E = VD->getInit()) {
1608 if (const UnaryOperator *UO = dyn_cast<UnaryOperator>(Exp)) {
1610 if (UO->getOpcode() == clang::UO_Deref)
1611 checkPtAccess(UO->getSubExpr(), AK, POK);
1615 if (const ArraySubscriptExpr *AE = dyn_cast<ArraySubscriptExpr>(Exp)) {
1616 checkPtAccess(AE->getLHS(), AK, POK);
1620 if (const MemberExpr *ME = dyn_cast<MemberExpr>(Exp)) {
1622 checkPtAccess(ME->getBase(), AK, POK);
1624 checkAccess(ME->getBase(), AK, POK);
1627 const ValueDecl *D = getValueDecl(Exp);
1628 if (!D || !D->hasAttrs())
1631 if (D->hasAttr<GuardedVarAttr>() && FSet.isEmpty(Analyzer->FactMan)) {
1632 Analyzer->Handler.handleNoMutexHeld("mutex", D, POK, AK, Loc);
1635 for (const auto *I : D->specific_attrs<GuardedByAttr>())
1636 warnIfMutexNotHeld(D, Exp, AK, I->getArg(), POK,
1637 ClassifyDiagnostic(I), Loc);
1641 /// \brief Checks pt_guarded_by and pt_guarded_var attributes.
1642 /// POK is the same operationKind that was passed to checkAccess.
1643 void BuildLockset::checkPtAccess(const Expr *Exp, AccessKind AK,
1644 ProtectedOperationKind POK) {
1646 if (const ParenExpr *PE = dyn_cast<ParenExpr>(Exp)) {
1647 Exp = PE->getSubExpr();
1650 if (const CastExpr *CE = dyn_cast<CastExpr>(Exp)) {
1651 if (CE->getCastKind() == CK_ArrayToPointerDecay) {
1652 // If it's an actual array, and not a pointer, then it's elements
1653 // are protected by GUARDED_BY, not PT_GUARDED_BY;
1654 checkAccess(CE->getSubExpr(), AK, POK);
1657 Exp = CE->getSubExpr();
1663 // Pass by reference warnings are under a different flag.
1664 ProtectedOperationKind PtPOK = POK_VarDereference;
1665 if (POK == POK_PassByRef) PtPOK = POK_PtPassByRef;
1667 const ValueDecl *D = getValueDecl(Exp);
1668 if (!D || !D->hasAttrs())
1671 if (D->hasAttr<PtGuardedVarAttr>() && FSet.isEmpty(Analyzer->FactMan))
1672 Analyzer->Handler.handleNoMutexHeld("mutex", D, PtPOK, AK,
1675 for (auto const *I : D->specific_attrs<PtGuardedByAttr>())
1676 warnIfMutexNotHeld(D, Exp, AK, I->getArg(), PtPOK,
1677 ClassifyDiagnostic(I), Exp->getExprLoc());
1680 /// \brief Process a function call, method call, constructor call,
1681 /// or destructor call. This involves looking at the attributes on the
1682 /// corresponding function/method/constructor/destructor, issuing warnings,
1683 /// and updating the locksets accordingly.
1685 /// FIXME: For classes annotated with one of the guarded annotations, we need
1686 /// to treat const method calls as reads and non-const method calls as writes,
1687 /// and check that the appropriate locks are held. Non-const method calls with
1688 /// the same signature as const method calls can be also treated as reads.
1690 void BuildLockset::handleCall(Expr *Exp, const NamedDecl *D, VarDecl *VD) {
1691 SourceLocation Loc = Exp->getExprLoc();
1692 CapExprSet ExclusiveLocksToAdd, SharedLocksToAdd;
1693 CapExprSet ExclusiveLocksToRemove, SharedLocksToRemove, GenericLocksToRemove;
1694 CapExprSet ScopedExclusiveReqs, ScopedSharedReqs;
1695 StringRef CapDiagKind = "mutex";
1697 // Figure out if we're calling the constructor of scoped lockable class
1698 bool isScopedVar = false;
1700 if (const CXXConstructorDecl *CD = dyn_cast<const CXXConstructorDecl>(D)) {
1701 const CXXRecordDecl* PD = CD->getParent();
1702 if (PD && PD->hasAttr<ScopedLockableAttr>())
1707 for(Attr *Atconst : D->attrs()) {
1708 Attr* At = const_cast<Attr*>(Atconst);
1709 switch (At->getKind()) {
1710 // When we encounter a lock function, we need to add the lock to our
1712 case attr::AcquireCapability: {
1713 auto *A = cast<AcquireCapabilityAttr>(At);
1714 Analyzer->getMutexIDs(A->isShared() ? SharedLocksToAdd
1715 : ExclusiveLocksToAdd,
1718 CapDiagKind = ClassifyDiagnostic(A);
1722 // An assert will add a lock to the lockset, but will not generate
1723 // a warning if it is already there, and will not generate a warning
1724 // if it is not removed.
1725 case attr::AssertExclusiveLock: {
1726 AssertExclusiveLockAttr *A = cast<AssertExclusiveLockAttr>(At);
1728 CapExprSet AssertLocks;
1729 Analyzer->getMutexIDs(AssertLocks, A, Exp, D, VD);
1730 for (const auto &AssertLock : AssertLocks)
1731 Analyzer->addLock(FSet,
1732 llvm::make_unique<LockableFactEntry>(
1733 AssertLock, LK_Exclusive, Loc, false, true),
1734 ClassifyDiagnostic(A));
1737 case attr::AssertSharedLock: {
1738 AssertSharedLockAttr *A = cast<AssertSharedLockAttr>(At);
1740 CapExprSet AssertLocks;
1741 Analyzer->getMutexIDs(AssertLocks, A, Exp, D, VD);
1742 for (const auto &AssertLock : AssertLocks)
1743 Analyzer->addLock(FSet, llvm::make_unique<LockableFactEntry>(
1744 AssertLock, LK_Shared, Loc, false, true),
1745 ClassifyDiagnostic(A));
1749 // When we encounter an unlock function, we need to remove unlocked
1750 // mutexes from the lockset, and flag a warning if they are not there.
1751 case attr::ReleaseCapability: {
1752 auto *A = cast<ReleaseCapabilityAttr>(At);
1754 Analyzer->getMutexIDs(GenericLocksToRemove, A, Exp, D, VD);
1755 else if (A->isShared())
1756 Analyzer->getMutexIDs(SharedLocksToRemove, A, Exp, D, VD);
1758 Analyzer->getMutexIDs(ExclusiveLocksToRemove, A, Exp, D, VD);
1760 CapDiagKind = ClassifyDiagnostic(A);
1764 case attr::RequiresCapability: {
1765 RequiresCapabilityAttr *A = cast<RequiresCapabilityAttr>(At);
1766 for (auto *Arg : A->args()) {
1767 warnIfMutexNotHeld(D, Exp, A->isShared() ? AK_Read : AK_Written, Arg,
1768 POK_FunctionCall, ClassifyDiagnostic(A),
1770 // use for adopting a lock
1772 Analyzer->getMutexIDs(A->isShared() ? ScopedSharedReqs
1773 : ScopedExclusiveReqs,
1780 case attr::LocksExcluded: {
1781 LocksExcludedAttr *A = cast<LocksExcludedAttr>(At);
1782 for (auto *Arg : A->args())
1783 warnIfMutexHeld(D, Exp, Arg, ClassifyDiagnostic(A));
1787 // Ignore attributes unrelated to thread-safety
1794 for (const auto &M : ExclusiveLocksToAdd)
1795 Analyzer->addLock(FSet, llvm::make_unique<LockableFactEntry>(
1796 M, LK_Exclusive, Loc, isScopedVar),
1798 for (const auto &M : SharedLocksToAdd)
1799 Analyzer->addLock(FSet, llvm::make_unique<LockableFactEntry>(
1800 M, LK_Shared, Loc, isScopedVar),
1804 // Add the managing object as a dummy mutex, mapped to the underlying mutex.
1805 SourceLocation MLoc = VD->getLocation();
1806 DeclRefExpr DRE(VD, false, VD->getType(), VK_LValue, VD->getLocation());
1807 // FIXME: does this store a pointer to DRE?
1808 CapabilityExpr Scp = Analyzer->SxBuilder.translateAttrExpr(&DRE, nullptr);
1810 std::copy(ScopedExclusiveReqs.begin(), ScopedExclusiveReqs.end(),
1811 std::back_inserter(ExclusiveLocksToAdd));
1812 std::copy(ScopedSharedReqs.begin(), ScopedSharedReqs.end(),
1813 std::back_inserter(SharedLocksToAdd));
1814 Analyzer->addLock(FSet,
1815 llvm::make_unique<ScopedLockableFactEntry>(
1816 Scp, MLoc, ExclusiveLocksToAdd, SharedLocksToAdd),
1821 // FIXME -- should only fully remove if the attribute refers to 'this'.
1822 bool Dtor = isa<CXXDestructorDecl>(D);
1823 for (const auto &M : ExclusiveLocksToRemove)
1824 Analyzer->removeLock(FSet, M, Loc, Dtor, LK_Exclusive, CapDiagKind);
1825 for (const auto &M : SharedLocksToRemove)
1826 Analyzer->removeLock(FSet, M, Loc, Dtor, LK_Shared, CapDiagKind);
1827 for (const auto &M : GenericLocksToRemove)
1828 Analyzer->removeLock(FSet, M, Loc, Dtor, LK_Generic, CapDiagKind);
1832 /// \brief For unary operations which read and write a variable, we need to
1833 /// check whether we hold any required mutexes. Reads are checked in
1835 void BuildLockset::VisitUnaryOperator(UnaryOperator *UO) {
1836 switch (UO->getOpcode()) {
1837 case clang::UO_PostDec:
1838 case clang::UO_PostInc:
1839 case clang::UO_PreDec:
1840 case clang::UO_PreInc: {
1841 checkAccess(UO->getSubExpr(), AK_Written);
1849 /// For binary operations which assign to a variable (writes), we need to check
1850 /// whether we hold any required mutexes.
1851 /// FIXME: Deal with non-primitive types.
1852 void BuildLockset::VisitBinaryOperator(BinaryOperator *BO) {
1853 if (!BO->isAssignmentOp())
1856 // adjust the context
1857 LVarCtx = Analyzer->LocalVarMap.getNextContext(CtxIndex, BO, LVarCtx);
1859 checkAccess(BO->getLHS(), AK_Written);
1863 /// Whenever we do an LValue to Rvalue cast, we are reading a variable and
1864 /// need to ensure we hold any required mutexes.
1865 /// FIXME: Deal with non-primitive types.
1866 void BuildLockset::VisitCastExpr(CastExpr *CE) {
1867 if (CE->getCastKind() != CK_LValueToRValue)
1869 checkAccess(CE->getSubExpr(), AK_Read);
1873 void BuildLockset::VisitCallExpr(CallExpr *Exp) {
1874 bool ExamineArgs = true;
1875 bool OperatorFun = false;
1877 if (CXXMemberCallExpr *CE = dyn_cast<CXXMemberCallExpr>(Exp)) {
1878 MemberExpr *ME = dyn_cast<MemberExpr>(CE->getCallee());
1879 // ME can be null when calling a method pointer
1880 CXXMethodDecl *MD = CE->getMethodDecl();
1883 if (ME->isArrow()) {
1884 if (MD->isConst()) {
1885 checkPtAccess(CE->getImplicitObjectArgument(), AK_Read);
1886 } else { // FIXME -- should be AK_Written
1887 checkPtAccess(CE->getImplicitObjectArgument(), AK_Read);
1891 checkAccess(CE->getImplicitObjectArgument(), AK_Read);
1892 else // FIXME -- should be AK_Written
1893 checkAccess(CE->getImplicitObjectArgument(), AK_Read);
1896 } else if (CXXOperatorCallExpr *OE = dyn_cast<CXXOperatorCallExpr>(Exp)) {
1899 auto OEop = OE->getOperator();
1902 ExamineArgs = false;
1903 const Expr *Target = OE->getArg(0);
1904 const Expr *Source = OE->getArg(1);
1905 checkAccess(Target, AK_Written);
1906 checkAccess(Source, AK_Read);
1911 case OO_Subscript: {
1912 const Expr *Obj = OE->getArg(0);
1913 checkAccess(Obj, AK_Read);
1914 if (!(OEop == OO_Star && OE->getNumArgs() > 1)) {
1915 // Grrr. operator* can be multiplication...
1916 checkPtAccess(Obj, AK_Read);
1921 // TODO: get rid of this, and rely on pass-by-ref instead.
1922 const Expr *Obj = OE->getArg(0);
1923 checkAccess(Obj, AK_Read);
1931 if (FunctionDecl *FD = Exp->getDirectCallee()) {
1932 unsigned Fn = FD->getNumParams();
1933 unsigned Cn = Exp->getNumArgs();
1938 if (isa<CXXMethodDecl>(FD)) {
1939 // First arg in operator call is implicit self argument,
1940 // and doesn't appear in the FunctionDecl.
1944 // Ignore the first argument of operators; it's been checked above.
1948 // Ignore default arguments
1949 unsigned n = (Fn < Cn) ? Fn : Cn;
1951 for (; i < n; ++i) {
1952 ParmVarDecl* Pvd = FD->getParamDecl(i);
1953 Expr* Arg = Exp->getArg(i+Skip);
1954 QualType Qt = Pvd->getType();
1955 if (Qt->isReferenceType())
1956 checkAccess(Arg, AK_Read, POK_PassByRef);
1961 NamedDecl *D = dyn_cast_or_null<NamedDecl>(Exp->getCalleeDecl());
1962 if(!D || !D->hasAttrs())
1967 void BuildLockset::VisitCXXConstructExpr(CXXConstructExpr *Exp) {
1968 const CXXConstructorDecl *D = Exp->getConstructor();
1969 if (D && D->isCopyConstructor()) {
1970 const Expr* Source = Exp->getArg(0);
1971 checkAccess(Source, AK_Read);
1973 // FIXME -- only handles constructors in DeclStmt below.
1976 void BuildLockset::VisitDeclStmt(DeclStmt *S) {
1977 // adjust the context
1978 LVarCtx = Analyzer->LocalVarMap.getNextContext(CtxIndex, S, LVarCtx);
1980 for (auto *D : S->getDeclGroup()) {
1981 if (VarDecl *VD = dyn_cast_or_null<VarDecl>(D)) {
1982 Expr *E = VD->getInit();
1983 // handle constructors that involve temporaries
1984 if (ExprWithCleanups *EWC = dyn_cast_or_null<ExprWithCleanups>(E))
1985 E = EWC->getSubExpr();
1987 if (CXXConstructExpr *CE = dyn_cast_or_null<CXXConstructExpr>(E)) {
1988 NamedDecl *CtorD = dyn_cast_or_null<NamedDecl>(CE->getConstructor());
1989 if (!CtorD || !CtorD->hasAttrs())
1991 handleCall(CE, CtorD, VD);
1999 /// \brief Compute the intersection of two locksets and issue warnings for any
2000 /// locks in the symmetric difference.
2002 /// This function is used at a merge point in the CFG when comparing the lockset
2003 /// of each branch being merged. For example, given the following sequence:
2004 /// A; if () then B; else C; D; we need to check that the lockset after B and C
2005 /// are the same. In the event of a difference, we use the intersection of these
2006 /// two locksets at the start of D.
2008 /// \param FSet1 The first lockset.
2009 /// \param FSet2 The second lockset.
2010 /// \param JoinLoc The location of the join point for error reporting
2011 /// \param LEK1 The error message to report if a mutex is missing from LSet1
2012 /// \param LEK2 The error message to report if a mutex is missing from Lset2
2013 void ThreadSafetyAnalyzer::intersectAndWarn(FactSet &FSet1,
2014 const FactSet &FSet2,
2015 SourceLocation JoinLoc,
2019 FactSet FSet1Orig = FSet1;
2021 // Find locks in FSet2 that conflict or are not in FSet1, and warn.
2022 for (const auto &Fact : FSet2) {
2023 const FactEntry *LDat1 = nullptr;
2024 const FactEntry *LDat2 = &FactMan[Fact];
2025 FactSet::iterator Iter1 = FSet1.findLockIter(FactMan, *LDat2);
2026 if (Iter1 != FSet1.end()) LDat1 = &FactMan[*Iter1];
2029 if (LDat1->kind() != LDat2->kind()) {
2030 Handler.handleExclusiveAndShared("mutex", LDat2->toString(),
2031 LDat2->loc(), LDat1->loc());
2032 if (Modify && LDat1->kind() != LK_Exclusive) {
2033 // Take the exclusive lock, which is the one in FSet2.
2037 else if (Modify && LDat1->asserted() && !LDat2->asserted()) {
2038 // The non-asserted lock in FSet2 is the one we want to track.
2042 LDat2->handleRemovalFromIntersection(FSet2, FactMan, JoinLoc, LEK1,
2047 // Find locks in FSet1 that are not in FSet2, and remove them.
2048 for (const auto &Fact : FSet1Orig) {
2049 const FactEntry *LDat1 = &FactMan[Fact];
2050 const FactEntry *LDat2 = FSet2.findLock(FactMan, *LDat1);
2053 LDat1->handleRemovalFromIntersection(FSet1Orig, FactMan, JoinLoc, LEK2,
2056 FSet1.removeLock(FactMan, *LDat1);
2062 // Return true if block B never continues to its successors.
2063 static bool neverReturns(const CFGBlock *B) {
2064 if (B->hasNoReturnElement())
2069 CFGElement Last = B->back();
2070 if (Optional<CFGStmt> S = Last.getAs<CFGStmt>()) {
2071 if (isa<CXXThrowExpr>(S->getStmt()))
2078 /// \brief Check a function's CFG for thread-safety violations.
2080 /// We traverse the blocks in the CFG, compute the set of mutexes that are held
2081 /// at the end of each block, and issue warnings for thread safety violations.
2082 /// Each block in the CFG is traversed exactly once.
2083 void ThreadSafetyAnalyzer::runAnalysis(AnalysisDeclContext &AC) {
2084 // TODO: this whole function needs be rewritten as a visitor for CFGWalker.
2085 // For now, we just use the walker to set things up.
2086 threadSafety::CFGWalker walker;
2087 if (!walker.init(AC))
2090 // AC.dumpCFG(true);
2091 // threadSafety::printSCFG(walker);
2093 CFG *CFGraph = walker.getGraph();
2094 const NamedDecl *D = walker.getDecl();
2095 const FunctionDecl *CurrentFunction = dyn_cast<FunctionDecl>(D);
2096 CurrentMethod = dyn_cast<CXXMethodDecl>(D);
2098 if (D->hasAttr<NoThreadSafetyAnalysisAttr>())
2101 // FIXME: Do something a bit more intelligent inside constructor and
2102 // destructor code. Constructors and destructors must assume unique access
2103 // to 'this', so checks on member variable access is disabled, but we should
2104 // still enable checks on other objects.
2105 if (isa<CXXConstructorDecl>(D))
2106 return; // Don't check inside constructors.
2107 if (isa<CXXDestructorDecl>(D))
2108 return; // Don't check inside destructors.
2110 Handler.enterFunction(CurrentFunction);
2112 BlockInfo.resize(CFGraph->getNumBlockIDs(),
2113 CFGBlockInfo::getEmptyBlockInfo(LocalVarMap));
2115 // We need to explore the CFG via a "topological" ordering.
2116 // That way, we will be guaranteed to have information about required
2117 // predecessor locksets when exploring a new block.
2118 const PostOrderCFGView *SortedGraph = walker.getSortedGraph();
2119 PostOrderCFGView::CFGBlockSet VisitedBlocks(CFGraph);
2121 // Mark entry block as reachable
2122 BlockInfo[CFGraph->getEntry().getBlockID()].Reachable = true;
2124 // Compute SSA names for local variables
2125 LocalVarMap.traverseCFG(CFGraph, SortedGraph, BlockInfo);
2127 // Fill in source locations for all CFGBlocks.
2128 findBlockLocations(CFGraph, SortedGraph, BlockInfo);
2130 CapExprSet ExclusiveLocksAcquired;
2131 CapExprSet SharedLocksAcquired;
2132 CapExprSet LocksReleased;
2134 // Add locks from exclusive_locks_required and shared_locks_required
2135 // to initial lockset. Also turn off checking for lock and unlock functions.
2136 // FIXME: is there a more intelligent way to check lock/unlock functions?
2137 if (!SortedGraph->empty() && D->hasAttrs()) {
2138 const CFGBlock *FirstBlock = *SortedGraph->begin();
2139 FactSet &InitialLockset = BlockInfo[FirstBlock->getBlockID()].EntrySet;
2141 CapExprSet ExclusiveLocksToAdd;
2142 CapExprSet SharedLocksToAdd;
2143 StringRef CapDiagKind = "mutex";
2145 SourceLocation Loc = D->getLocation();
2146 for (const auto *Attr : D->attrs()) {
2147 Loc = Attr->getLocation();
2148 if (const auto *A = dyn_cast<RequiresCapabilityAttr>(Attr)) {
2149 getMutexIDs(A->isShared() ? SharedLocksToAdd : ExclusiveLocksToAdd, A,
2151 CapDiagKind = ClassifyDiagnostic(A);
2152 } else if (const auto *A = dyn_cast<ReleaseCapabilityAttr>(Attr)) {
2153 // UNLOCK_FUNCTION() is used to hide the underlying lock implementation.
2154 // We must ignore such methods.
2155 if (A->args_size() == 0)
2157 // FIXME -- deal with exclusive vs. shared unlock functions?
2158 getMutexIDs(ExclusiveLocksToAdd, A, nullptr, D);
2159 getMutexIDs(LocksReleased, A, nullptr, D);
2160 CapDiagKind = ClassifyDiagnostic(A);
2161 } else if (const auto *A = dyn_cast<AcquireCapabilityAttr>(Attr)) {
2162 if (A->args_size() == 0)
2164 getMutexIDs(A->isShared() ? SharedLocksAcquired
2165 : ExclusiveLocksAcquired,
2167 CapDiagKind = ClassifyDiagnostic(A);
2168 } else if (isa<ExclusiveTrylockFunctionAttr>(Attr)) {
2169 // Don't try to check trylock functions for now
2171 } else if (isa<SharedTrylockFunctionAttr>(Attr)) {
2172 // Don't try to check trylock functions for now
2177 // FIXME -- Loc can be wrong here.
2178 for (const auto &Mu : ExclusiveLocksToAdd) {
2179 auto Entry = llvm::make_unique<LockableFactEntry>(Mu, LK_Exclusive, Loc);
2180 Entry->setDeclared(true);
2181 addLock(InitialLockset, std::move(Entry), CapDiagKind, true);
2183 for (const auto &Mu : SharedLocksToAdd) {
2184 auto Entry = llvm::make_unique<LockableFactEntry>(Mu, LK_Shared, Loc);
2185 Entry->setDeclared(true);
2186 addLock(InitialLockset, std::move(Entry), CapDiagKind, true);
2190 for (const auto *CurrBlock : *SortedGraph) {
2191 int CurrBlockID = CurrBlock->getBlockID();
2192 CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlockID];
2194 // Use the default initial lockset in case there are no predecessors.
2195 VisitedBlocks.insert(CurrBlock);
2197 // Iterate through the predecessor blocks and warn if the lockset for all
2198 // predecessors is not the same. We take the entry lockset of the current
2199 // block to be the intersection of all previous locksets.
2200 // FIXME: By keeping the intersection, we may output more errors in future
2201 // for a lock which is not in the intersection, but was in the union. We
2202 // may want to also keep the union in future. As an example, let's say
2203 // the intersection contains Mutex L, and the union contains L and M.
2204 // Later we unlock M. At this point, we would output an error because we
2205 // never locked M; although the real error is probably that we forgot to
2206 // lock M on all code paths. Conversely, let's say that later we lock M.
2207 // In this case, we should compare against the intersection instead of the
2208 // union because the real error is probably that we forgot to unlock M on
2210 bool LocksetInitialized = false;
2211 SmallVector<CFGBlock *, 8> SpecialBlocks;
2212 for (CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
2213 PE = CurrBlock->pred_end(); PI != PE; ++PI) {
2215 // if *PI -> CurrBlock is a back edge
2216 if (*PI == nullptr || !VisitedBlocks.alreadySet(*PI))
2219 int PrevBlockID = (*PI)->getBlockID();
2220 CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
2222 // Ignore edges from blocks that can't return.
2223 if (neverReturns(*PI) || !PrevBlockInfo->Reachable)
2226 // Okay, we can reach this block from the entry.
2227 CurrBlockInfo->Reachable = true;
2229 // If the previous block ended in a 'continue' or 'break' statement, then
2230 // a difference in locksets is probably due to a bug in that block, rather
2231 // than in some other predecessor. In that case, keep the other
2232 // predecessor's lockset.
2233 if (const Stmt *Terminator = (*PI)->getTerminator()) {
2234 if (isa<ContinueStmt>(Terminator) || isa<BreakStmt>(Terminator)) {
2235 SpecialBlocks.push_back(*PI);
2240 FactSet PrevLockset;
2241 getEdgeLockset(PrevLockset, PrevBlockInfo->ExitSet, *PI, CurrBlock);
2243 if (!LocksetInitialized) {
2244 CurrBlockInfo->EntrySet = PrevLockset;
2245 LocksetInitialized = true;
2247 intersectAndWarn(CurrBlockInfo->EntrySet, PrevLockset,
2248 CurrBlockInfo->EntryLoc,
2249 LEK_LockedSomePredecessors);
2253 // Skip rest of block if it's not reachable.
2254 if (!CurrBlockInfo->Reachable)
2257 // Process continue and break blocks. Assume that the lockset for the
2258 // resulting block is unaffected by any discrepancies in them.
2259 for (const auto *PrevBlock : SpecialBlocks) {
2260 int PrevBlockID = PrevBlock->getBlockID();
2261 CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
2263 if (!LocksetInitialized) {
2264 CurrBlockInfo->EntrySet = PrevBlockInfo->ExitSet;
2265 LocksetInitialized = true;
2267 // Determine whether this edge is a loop terminator for diagnostic
2268 // purposes. FIXME: A 'break' statement might be a loop terminator, but
2269 // it might also be part of a switch. Also, a subsequent destructor
2270 // might add to the lockset, in which case the real issue might be a
2271 // double lock on the other path.
2272 const Stmt *Terminator = PrevBlock->getTerminator();
2273 bool IsLoop = Terminator && isa<ContinueStmt>(Terminator);
2275 FactSet PrevLockset;
2276 getEdgeLockset(PrevLockset, PrevBlockInfo->ExitSet,
2277 PrevBlock, CurrBlock);
2279 // Do not update EntrySet.
2280 intersectAndWarn(CurrBlockInfo->EntrySet, PrevLockset,
2281 PrevBlockInfo->ExitLoc,
2282 IsLoop ? LEK_LockedSomeLoopIterations
2283 : LEK_LockedSomePredecessors,
2288 BuildLockset LocksetBuilder(this, *CurrBlockInfo);
2290 // Visit all the statements in the basic block.
2291 for (CFGBlock::const_iterator BI = CurrBlock->begin(),
2292 BE = CurrBlock->end(); BI != BE; ++BI) {
2293 switch (BI->getKind()) {
2294 case CFGElement::Statement: {
2295 CFGStmt CS = BI->castAs<CFGStmt>();
2296 LocksetBuilder.Visit(const_cast<Stmt*>(CS.getStmt()));
2299 // Ignore BaseDtor, MemberDtor, and TemporaryDtor for now.
2300 case CFGElement::AutomaticObjectDtor: {
2301 CFGAutomaticObjDtor AD = BI->castAs<CFGAutomaticObjDtor>();
2302 CXXDestructorDecl *DD = const_cast<CXXDestructorDecl *>(
2303 AD.getDestructorDecl(AC.getASTContext()));
2304 if (!DD->hasAttrs())
2307 // Create a dummy expression,
2308 VarDecl *VD = const_cast<VarDecl*>(AD.getVarDecl());
2309 DeclRefExpr DRE(VD, false, VD->getType().getNonReferenceType(),
2310 VK_LValue, AD.getTriggerStmt()->getLocEnd());
2311 LocksetBuilder.handleCall(&DRE, DD);
2318 CurrBlockInfo->ExitSet = LocksetBuilder.FSet;
2320 // For every back edge from CurrBlock (the end of the loop) to another block
2321 // (FirstLoopBlock) we need to check that the Lockset of Block is equal to
2322 // the one held at the beginning of FirstLoopBlock. We can look up the
2323 // Lockset held at the beginning of FirstLoopBlock in the EntryLockSets map.
2324 for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
2325 SE = CurrBlock->succ_end(); SI != SE; ++SI) {
2327 // if CurrBlock -> *SI is *not* a back edge
2328 if (*SI == nullptr || !VisitedBlocks.alreadySet(*SI))
2331 CFGBlock *FirstLoopBlock = *SI;
2332 CFGBlockInfo *PreLoop = &BlockInfo[FirstLoopBlock->getBlockID()];
2333 CFGBlockInfo *LoopEnd = &BlockInfo[CurrBlockID];
2334 intersectAndWarn(LoopEnd->ExitSet, PreLoop->EntrySet,
2336 LEK_LockedSomeLoopIterations,
2341 CFGBlockInfo *Initial = &BlockInfo[CFGraph->getEntry().getBlockID()];
2342 CFGBlockInfo *Final = &BlockInfo[CFGraph->getExit().getBlockID()];
2344 // Skip the final check if the exit block is unreachable.
2345 if (!Final->Reachable)
2348 // By default, we expect all locks held on entry to be held on exit.
2349 FactSet ExpectedExitSet = Initial->EntrySet;
2351 // Adjust the expected exit set by adding or removing locks, as declared
2352 // by *-LOCK_FUNCTION and UNLOCK_FUNCTION. The intersect below will then
2353 // issue the appropriate warning.
2354 // FIXME: the location here is not quite right.
2355 for (const auto &Lock : ExclusiveLocksAcquired)
2356 ExpectedExitSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
2357 Lock, LK_Exclusive, D->getLocation()));
2358 for (const auto &Lock : SharedLocksAcquired)
2359 ExpectedExitSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
2360 Lock, LK_Shared, D->getLocation()));
2361 for (const auto &Lock : LocksReleased)
2362 ExpectedExitSet.removeLock(FactMan, Lock);
2364 // FIXME: Should we call this function for all blocks which exit the function?
2365 intersectAndWarn(ExpectedExitSet, Final->ExitSet,
2367 LEK_LockedAtEndOfFunction,
2368 LEK_NotLockedAtEndOfFunction,
2371 Handler.leaveFunction(CurrentFunction);
2375 /// \brief Check a function's CFG for thread-safety violations.
2377 /// We traverse the blocks in the CFG, compute the set of mutexes that are held
2378 /// at the end of each block, and issue warnings for thread safety violations.
2379 /// Each block in the CFG is traversed exactly once.
2380 void threadSafety::runThreadSafetyAnalysis(AnalysisDeclContext &AC,
2381 ThreadSafetyHandler &Handler,
2384 *BSet = new BeforeSet;
2385 ThreadSafetyAnalyzer Analyzer(Handler, *BSet);
2386 Analyzer.runAnalysis(AC);
2389 void threadSafety::threadSafetyCleanup(BeforeSet *Cache) { delete Cache; }
2391 /// \brief Helper function that returns a LockKind required for the given level
2393 LockKind threadSafety::getLockKindFromAccessKind(AccessKind AK) {
2398 return LK_Exclusive;
2400 llvm_unreachable("Unknown AccessKind");