--- /dev/null
+//===- ThreadSafety.h ------------------------------------------*- C++ --*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//
+// A intra-procedural analysis for thread safety (e.g. deadlocks and race
+// conditions), based off of an annotation system.
+//
+// See http://gcc.gnu.org/wiki/ThreadSafetyAnnotation for the gcc version.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_THREADSAFETY_H
+#define LLVM_CLANG_THREADSAFETY_H
+
+#include "clang/Basic/SourceLocation.h"
+#include "llvm/ADT/StringRef.h"
+#include "clang/Analysis/AnalysisContext.h"
+#include "clang/Sema/SemaInternal.h"
+
+namespace clang {
+namespace thread_safety {
+
+enum ProtectedOperationKind {
+ POK_VarDereference,
+ POK_VarAccess,
+ POK_FunctionCall
+};
+
+enum LockKind {
+ LK_Shared,
+ LK_Exclusive
+};
+
+enum AccessKind {
+ AK_Read,
+ AK_Written
+};
+
+class ThreadSafetyHandler {
+public:
+ typedef llvm::StringRef Name;
+ ThreadSafetyHandler() {}
+ virtual ~ThreadSafetyHandler() {}
+ virtual void handleUnmatchedUnlock(Name LockName, SourceLocation Loc) {}
+ virtual void handleDoubleLock(Name LockName, SourceLocation Loc) {}
+ virtual void handleMutexHeldEndOfScope(Name LockName, SourceLocation Loc){}
+ virtual void handleNoLockLoopEntry(Name LockName, SourceLocation Loc) {}
+ virtual void handleNoUnlock(Name LockName, Name FunName,
+ SourceLocation Loc) {}
+ virtual void handleExclusiveAndShared(Name LockName, SourceLocation Loc1,
+ SourceLocation Loc2) {}
+ virtual void handleNoMutexHeld(const NamedDecl *D, ProtectedOperationKind POK,
+ AccessKind AK, SourceLocation Loc) {}
+ virtual void handleMutexNotHeld(const NamedDecl *D,
+ ProtectedOperationKind POK, Name LockName,
+ LockKind LK, SourceLocation Loc) {}
+ virtual void handleFunExcludesLock(Name FunName, Name LockName,
+ SourceLocation Loc) {}
+};
+
+void runThreadSafetyAnalysis(AnalysisContext &AC, ThreadSafetyHandler &Handler);
+LockKind getLockKindFromAccessKind(AccessKind AK);
+
+}} // end namespace clang::thread_safety
+#endif
PseudoConstantAnalysis.cpp
ReachableCode.cpp
ScanfFormatString.cpp
+ ThreadSafety.cpp
UninitializedValues.cpp
)
--- /dev/null
+//===- ThreadSafety.cpp ----------------------------------------*- C++ --*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// A intra-procedural analysis for thread safety (e.g. deadlocks and race
+// conditions), based off of an annotation system.
+//
+// See http://gcc.gnu.org/wiki/ThreadSafetyAnnotation for the gcc version.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Analysis/Analyses/ThreadSafety.h"
+#include "clang/Sema/SemaInternal.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Basic/SourceLocation.h"
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/ExprCXX.h"
+#include "clang/AST/StmtCXX.h"
+#include "clang/AST/StmtVisitor.h"
+#include "clang/Analysis/AnalysisContext.h"
+#include "clang/Analysis/CFG.h"
+#include "clang/Analysis/CFGStmtMap.h"
+#include "llvm/ADT/BitVector.h"
+#include "llvm/ADT/FoldingSet.h"
+#include "llvm/ADT/ImmutableMap.h"
+#include "llvm/ADT/PostOrderIterator.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
+#include <algorithm>
+#include <vector>
+
+using namespace clang;
+using namespace thread_safety;
+
+namespace {
+/// \brief Implements a set of CFGBlocks using a BitVector.
+///
+/// This class contains a minimal interface, primarily dictated by the SetType
+/// template parameter of the llvm::po_iterator template, as used with external
+/// storage. We also use this set to keep track of which CFGBlocks we visit
+/// during the analysis.
+class CFGBlockSet {
+ llvm::BitVector VisitedBlockIDs;
+
+public:
+ // po_iterator requires this iterator, but the only interface needed is the
+ // value_type typedef.
+ struct iterator {
+ typedef const CFGBlock *value_type;
+ };
+
+ CFGBlockSet() {}
+ CFGBlockSet(const CFG *G) : VisitedBlockIDs(G->getNumBlockIDs(), false) {}
+
+ /// \brief Set the bit associated with a particular CFGBlock.
+ /// This is the important method for the SetType template parameter.
+ bool insert(const CFGBlock *Block) {
+ // Note that insert() is called by po_iterator, which doesn't check to make
+ // sure that Block is non-null. Moreover, the CFGBlock iterator will
+ // occasionally hand out null pointers for pruned edges, so we catch those
+ // here.
+ if (Block == 0)
+ return false; // if an edge is trivially false.
+ if (VisitedBlockIDs.test(Block->getBlockID()))
+ return false;
+ VisitedBlockIDs.set(Block->getBlockID());
+ return true;
+ }
+
+ /// \brief Check if the bit for a CFGBlock has been already set.
+ /// This method is for tracking visited blocks in the main threadsafety loop.
+ /// Block must not be null.
+ bool alreadySet(const CFGBlock *Block) {
+ return VisitedBlockIDs.test(Block->getBlockID());
+ }
+};
+
+/// \brief We create a helper class which we use to iterate through CFGBlocks in
+/// the topological order.
+class TopologicallySortedCFG {
+ typedef llvm::po_iterator<const CFG*, CFGBlockSet, true> po_iterator;
+
+ std::vector<const CFGBlock*> Blocks;
+
+public:
+ typedef std::vector<const CFGBlock*>::reverse_iterator iterator;
+
+ TopologicallySortedCFG(const CFG *CFGraph) {
+ Blocks.reserve(CFGraph->getNumBlockIDs());
+ CFGBlockSet BSet(CFGraph);
+
+ for (po_iterator I = po_iterator::begin(CFGraph, BSet),
+ E = po_iterator::end(CFGraph, BSet); I != E; ++I) {
+ Blocks.push_back(*I);
+ }
+ }
+
+ iterator begin() {
+ return Blocks.rbegin();
+ }
+
+ iterator end() {
+ return Blocks.rend();
+ }
+};
+
+/// \brief A MutexID object uniquely identifies a particular mutex, and
+/// is built from an Expr* (i.e. calling a lock function).
+///
+/// Thread-safety analysis works by comparing lock expressions. Within the
+/// body of a function, an expression such as "x->foo->bar.mu" will resolve to
+/// a particular mutex object at run-time. Subsequent occurrences of the same
+/// expression (where "same" means syntactic equality) will refer to the same
+/// run-time object if three conditions hold:
+/// (1) Local variables in the expression, such as "x" have not changed.
+/// (2) Values on the heap that affect the expression have not changed.
+/// (3) The expression involves only pure function calls.
+/// The current implementation assumes, but does not verify, that multiple uses
+/// of the same lock expression satisfies these criteria.
+///
+/// Clang introduces an additional wrinkle, which is that it is difficult to
+/// derive canonical expressions, or compare expressions directly for equality.
+/// Thus, we identify a mutex not by an Expr, but by the set of named
+/// declarations that are referenced by the Expr. In other words,
+/// x->foo->bar.mu will be a four element vector with the Decls for
+/// mu, bar, and foo, and x. The vector will uniquely identify the expression
+/// for all practical purposes.
+///
+/// Note we will need to perform substitution on "this" and function parameter
+/// names when constructing a lock expression.
+///
+/// For example:
+/// class C { Mutex Mu; void lock() EXCLUSIVE_LOCK_FUNCTION(this->Mu); };
+/// void myFunc(C *X) { ... X->lock() ... }
+/// The original expression for the mutex acquired by myFunc is "this->Mu", but
+/// "X" is substituted for "this" so we get X->Mu();
+///
+/// For another example:
+/// foo(MyList *L) EXCLUSIVE_LOCKS_REQUIRED(L->Mu) { ... }
+/// MyList *MyL;
+/// foo(MyL); // requires lock MyL->Mu to be held
+class MutexID {
+ SmallVector<NamedDecl*, 2> DeclSeq;
+
+ /// Build a Decl sequence representing the lock from the given expression.
+ /// Recursive function that bottoms out when the final DeclRefExpr is reached.
+ void buildMutexID(Expr *Exp) {
+ if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Exp)) {
+ NamedDecl *ND = cast<NamedDecl>(DRE->getDecl()->getCanonicalDecl());
+ DeclSeq.push_back(ND);
+ } else if (MemberExpr *ME = dyn_cast<MemberExpr>(Exp)) {
+ NamedDecl *ND = ME->getMemberDecl();
+ DeclSeq.push_back(ND);
+ buildMutexID(ME->getBase());
+ } else if (isa<CXXThisExpr>(Exp)) {
+ return;
+ } else {
+ // FIXME: add diagnostic
+ llvm::report_fatal_error("Expected lock expression!");
+ }
+ }
+
+public:
+ MutexID(Expr *LExpr) {
+ buildMutexID(LExpr);
+ assert(!DeclSeq.empty());
+ }
+
+ bool operator==(const MutexID &other) const {
+ return DeclSeq == other.DeclSeq;
+ }
+
+ bool operator!=(const MutexID &other) const {
+ return !(*this == other);
+ }
+
+ // SmallVector overloads Operator< to do lexicographic ordering. Note that
+ // we use pointer equality (and <) to compare NamedDecls. This means the order
+ // of MutexIDs in a lockset is nondeterministic. In order to output
+ // diagnostics in a deterministic ordering, we must order all diagnostics to
+ // output by SourceLocation when iterating through this lockset.
+ bool operator<(const MutexID &other) const {
+ return DeclSeq < other.DeclSeq;
+ }
+
+ /// \brief Returns the name of the first Decl in the list for a given MutexID;
+ /// e.g. the lock expression foo.bar() has name "bar".
+ /// The caret will point unambiguously to the lock expression, so using this
+ /// name in diagnostics is a way to get simple, and consistent, mutex names.
+ /// We do not want to output the entire expression text for security reasons.
+ StringRef getName() const {
+ return DeclSeq.front()->getName();
+ }
+
+ void Profile(llvm::FoldingSetNodeID &ID) const {
+ for (SmallVectorImpl<NamedDecl*>::const_iterator I = DeclSeq.begin(),
+ E = DeclSeq.end(); I != E; ++I) {
+ ID.AddPointer(*I);
+ }
+ }
+};
+
+/// \brief This is a helper class that stores info about the most recent
+/// accquire of a Lock.
+///
+/// The main body of the analysis maps MutexIDs to LockDatas.
+struct LockData {
+ SourceLocation AcquireLoc;
+
+ /// \brief LKind stores whether a lock is held shared or exclusively.
+ /// Note that this analysis does not currently support either re-entrant
+ /// locking or lock "upgrading" and "downgrading" between exclusive and
+ /// shared.
+ ///
+ /// FIXME: add support for re-entrant locking and lock up/downgrading
+ LockKind LKind;
+
+ LockData(SourceLocation AcquireLoc, LockKind LKind)
+ : AcquireLoc(AcquireLoc), LKind(LKind) {}
+
+ bool operator==(const LockData &other) const {
+ return AcquireLoc == other.AcquireLoc && LKind == other.LKind;
+ }
+
+ bool operator!=(const LockData &other) const {
+ return !(*this == other);
+ }
+
+ void Profile(llvm::FoldingSetNodeID &ID) const {
+ ID.AddInteger(AcquireLoc.getRawEncoding());
+ ID.AddInteger(LKind);
+ }
+};
+
+/// A Lockset maps each MutexID (defined above) to information about how it has
+/// been locked.
+typedef llvm::ImmutableMap<MutexID, LockData> Lockset;
+
+/// \brief We use this class to visit different types of expressions in
+/// CFGBlocks, and build up the lockset.
+/// An expression may cause us to add or remove locks from the lockset, or else
+/// output error messages related to missing locks.
+/// FIXME: In future, we may be able to not inherit from a visitor.
+class BuildLockset : public StmtVisitor<BuildLockset> {
+ ThreadSafetyHandler &Handler;
+ Lockset LSet;
+ Lockset::Factory &LocksetFactory;
+
+ // Helper functions
+ void removeLock(SourceLocation UnlockLoc, Expr *LockExp);
+ void addLock(SourceLocation LockLoc, Expr *LockExp, LockKind LK);
+ const ValueDecl *getValueDecl(Expr *Exp);
+ void warnIfMutexNotHeld (const NamedDecl *D, Expr *Exp, AccessKind AK,
+ Expr *MutexExp, ProtectedOperationKind POK);
+ void checkAccess(Expr *Exp, AccessKind AK);
+ void checkDereference(Expr *Exp, AccessKind AK);
+
+ template <class AttrType>
+ void addLocksToSet(LockKind LK, Attr *Attr, CXXMemberCallExpr *Exp);
+
+ /// \brief Returns true if the lockset contains a lock, regardless of whether
+ /// the lock is held exclusively or shared.
+ bool locksetContains(MutexID Lock) const {
+ return LSet.lookup(Lock);
+ }
+
+ /// \brief Returns true if the lockset contains a lock with the passed in
+ /// locktype.
+ bool locksetContains(MutexID Lock, LockKind KindRequested) const {
+ const LockData *LockHeld = LSet.lookup(Lock);
+ return (LockHeld && KindRequested == LockHeld->LKind);
+ }
+
+ /// \brief Returns true if the lockset contains a lock with at least the
+ /// passed in locktype. So for example, if we pass in LK_Shared, this function
+ /// returns true if the lock is held LK_Shared or LK_Exclusive. If we pass in
+ /// LK_Exclusive, this function returns true if the lock is held LK_Exclusive.
+ bool locksetContainsAtLeast(MutexID Lock, LockKind KindRequested) const {
+ switch (KindRequested) {
+ case LK_Shared:
+ return locksetContains(Lock);
+ case LK_Exclusive:
+ return locksetContains(Lock, KindRequested);
+ }
+ }
+
+public:
+ BuildLockset(ThreadSafetyHandler &Handler, Lockset LS, Lockset::Factory &F)
+ : StmtVisitor<BuildLockset>(), Handler(Handler), LSet(LS),
+ LocksetFactory(F) {}
+
+ Lockset getLockset() {
+ return LSet;
+ }
+
+ void VisitUnaryOperator(UnaryOperator *UO);
+ void VisitBinaryOperator(BinaryOperator *BO);
+ void VisitCastExpr(CastExpr *CE);
+ void VisitCXXMemberCallExpr(CXXMemberCallExpr *Exp);
+};
+
+/// \brief Add a new lock to the lockset, warning if the lock is already there.
+/// \param LockLoc The source location of the acquire
+/// \param LockExp The lock expression corresponding to the lock to be added
+void BuildLockset::addLock(SourceLocation LockLoc, Expr *LockExp,
+ LockKind LK) {
+ // FIXME: deal with acquired before/after annotations
+ MutexID Mutex(LockExp);
+ LockData NewLock(LockLoc, LK);
+
+ // FIXME: Don't always warn when we have support for reentrant locks.
+ if (locksetContains(Mutex))
+ Handler.handleDoubleLock(Mutex.getName(), LockLoc);
+ LSet = LocksetFactory.add(LSet, Mutex, NewLock);
+}
+
+/// \brief Remove a lock from the lockset, warning if the lock is not there.
+/// \param LockExp The lock expression corresponding to the lock to be removed
+/// \param UnlockLoc The source location of the unlock (only used in error msg)
+void BuildLockset::removeLock(SourceLocation UnlockLoc, Expr *LockExp) {
+ MutexID Mutex(LockExp);
+
+ Lockset NewLSet = LocksetFactory.remove(LSet, Mutex);
+ if(NewLSet == LSet)
+ Handler.handleUnmatchedUnlock(Mutex.getName(), UnlockLoc);
+
+ LSet = NewLSet;
+}
+
+/// \brief Gets the value decl pointer from DeclRefExprs or MemberExprs
+const ValueDecl *BuildLockset::getValueDecl(Expr *Exp) {
+ if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Exp))
+ return DR->getDecl();
+
+ if (const MemberExpr *ME = dyn_cast<MemberExpr>(Exp))
+ return ME->getMemberDecl();
+
+ return 0;
+}
+
+/// \brief Warn if the LSet does not contain a lock sufficient to protect access
+/// of at least the passed in AccessType.
+void BuildLockset::warnIfMutexNotHeld(const NamedDecl *D, Expr *Exp,
+ AccessKind AK, Expr *MutexExp,
+ ProtectedOperationKind POK) {
+ LockKind LK = getLockKindFromAccessKind(AK);
+ MutexID Mutex(MutexExp);
+ if (!locksetContainsAtLeast(Mutex, LK))
+ Handler.handleMutexNotHeld(D, POK, Mutex.getName(), LK, Exp->getExprLoc());
+}
+
+
+/// \brief This method identifies variable dereferences and checks pt_guarded_by
+/// and pt_guarded_var annotations. Note that we only check these annotations
+/// at the time a pointer is dereferenced.
+/// FIXME: We need to check for other types of pointer dereferences
+/// (e.g. [], ->) and deal with them here.
+/// \param Exp An expression that has been read or written.
+void BuildLockset::checkDereference(Expr *Exp, AccessKind AK) {
+ UnaryOperator *UO = dyn_cast<UnaryOperator>(Exp);
+ if (!UO || UO->getOpcode() != clang::UO_Deref)
+ return;
+ Exp = UO->getSubExpr()->IgnoreParenCasts();
+
+ const ValueDecl *D = getValueDecl(Exp);
+ if(!D || !D->hasAttrs())
+ return;
+
+ if (D->getAttr<PtGuardedVarAttr>() && LSet.isEmpty())
+ Handler.handleNoMutexHeld(D, POK_VarDereference, AK, Exp->getExprLoc());
+
+ const AttrVec &ArgAttrs = D->getAttrs();
+ for(unsigned i = 0, Size = ArgAttrs.size(); i < Size; ++i)
+ if (PtGuardedByAttr *PGBAttr = dyn_cast<PtGuardedByAttr>(ArgAttrs[i]))
+ warnIfMutexNotHeld(D, Exp, AK, PGBAttr->getArg(), POK_VarDereference);
+}
+
+/// \brief Checks guarded_by and guarded_var attributes.
+/// Whenever we identify an access (read or write) of a DeclRefExpr or
+/// MemberExpr, we need to check whether there are any guarded_by or
+/// guarded_var attributes, and make sure we hold the appropriate mutexes.
+void BuildLockset::checkAccess(Expr *Exp, AccessKind AK) {
+ const ValueDecl *D = getValueDecl(Exp);
+ if(!D || !D->hasAttrs())
+ return;
+
+ if (D->getAttr<GuardedVarAttr>() && LSet.isEmpty())
+ Handler.handleNoMutexHeld(D, POK_VarAccess, AK, Exp->getExprLoc());
+
+ const AttrVec &ArgAttrs = D->getAttrs();
+ for(unsigned i = 0, Size = ArgAttrs.size(); i < Size; ++i)
+ if (GuardedByAttr *GBAttr = dyn_cast<GuardedByAttr>(ArgAttrs[i]))
+ warnIfMutexNotHeld(D, Exp, AK, GBAttr->getArg(), POK_VarAccess);
+}
+
+/// \brief For unary operations which read and write a variable, we need to
+/// check whether we hold any required mutexes. Reads are checked in
+/// VisitCastExpr.
+void BuildLockset::VisitUnaryOperator(UnaryOperator *UO) {
+ switch (UO->getOpcode()) {
+ case clang::UO_PostDec:
+ case clang::UO_PostInc:
+ case clang::UO_PreDec:
+ case clang::UO_PreInc: {
+ Expr *SubExp = UO->getSubExpr()->IgnoreParenCasts();
+ checkAccess(SubExp, AK_Written);
+ checkDereference(SubExp, AK_Written);
+ break;
+ }
+ default:
+ break;
+ }
+}
+
+/// For binary operations which assign to a variable (writes), we need to check
+/// whether we hold any required mutexes.
+/// FIXME: Deal with non-primitive types.
+void BuildLockset::VisitBinaryOperator(BinaryOperator *BO) {
+ if (!BO->isAssignmentOp())
+ return;
+ Expr *LHSExp = BO->getLHS()->IgnoreParenCasts();
+ checkAccess(LHSExp, AK_Written);
+ checkDereference(LHSExp, AK_Written);
+}
+
+/// Whenever we do an LValue to Rvalue cast, we are reading a variable and
+/// need to ensure we hold any required mutexes.
+/// FIXME: Deal with non-primitive types.
+void BuildLockset::VisitCastExpr(CastExpr *CE) {
+ if (CE->getCastKind() != CK_LValueToRValue)
+ return;
+ Expr *SubExp = CE->getSubExpr()->IgnoreParenCasts();
+ checkAccess(SubExp, AK_Read);
+ checkDereference(SubExp, AK_Read);
+}
+
+/// \brief This function, parameterized by an attribute type, is used to add a
+/// set of locks specified as attribute arguments to the lockset.
+template <typename AttrType>
+void BuildLockset::addLocksToSet(LockKind LK, Attr *Attr,
+ CXXMemberCallExpr *Exp) {
+ typedef typename AttrType::args_iterator iterator_type;
+ SourceLocation ExpLocation = Exp->getExprLoc();
+ Expr *Parent = Exp->getImplicitObjectArgument();
+ AttrType *SpecificAttr = cast<AttrType>(Attr);
+
+ if (SpecificAttr->args_size() == 0) {
+ // The mutex held is the "this" object.
+ addLock(ExpLocation, Parent, LK);
+ return;
+ }
+
+ for (iterator_type I = SpecificAttr->args_begin(),
+ E = SpecificAttr->args_end(); I != E; ++I)
+ addLock(ExpLocation, *I, LK);
+}
+
+/// \brief When visiting CXXMemberCallExprs we need to examine the attributes on
+/// the method that is being called and add, remove or check locks in the
+/// lockset accordingly.
+///
+/// FIXME: For classes annotated with one of the guarded annotations, we need
+/// to treat const method calls as reads and non-const method calls as writes,
+/// and check that the appropriate locks are held. Non-const method calls with
+/// the same signature as const method calls can be also treated as reads.
+///
+/// FIXME: We need to also visit CallExprs to catch/check global functions.
+void BuildLockset::VisitCXXMemberCallExpr(CXXMemberCallExpr *Exp) {
+ NamedDecl *D = dyn_cast_or_null<NamedDecl>(Exp->getCalleeDecl());
+
+ SourceLocation ExpLocation = Exp->getExprLoc();
+ Expr *Parent = Exp->getImplicitObjectArgument();
+
+ if(!D || !D->hasAttrs())
+ return;
+
+ AttrVec &ArgAttrs = D->getAttrs();
+ for(unsigned i = 0; i < ArgAttrs.size(); ++i) {
+ Attr *Attr = ArgAttrs[i];
+ switch (Attr->getKind()) {
+ // When we encounter an exclusive lock function, we need to add the lock
+ // to our lockset with kind exclusive.
+ case attr::ExclusiveLockFunction:
+ addLocksToSet<ExclusiveLockFunctionAttr>(LK_Exclusive, Attr, Exp);
+ break;
+
+ // When we encounter a shared lock function, we need to add the lock
+ // to our lockset with kind shared.
+ case attr::SharedLockFunction:
+ addLocksToSet<SharedLockFunctionAttr>(LK_Shared, Attr, Exp);
+ break;
+
+ // When we encounter an unlock function, we need to remove unlocked
+ // mutexes from the lockset, and flag a warning if they are not there.
+ case attr::UnlockFunction: {
+ UnlockFunctionAttr *UFAttr = cast<UnlockFunctionAttr>(Attr);
+
+ if (UFAttr->args_size() == 0) { // The lock held is the "this" object.
+ removeLock(ExpLocation, Parent);
+ break;
+ }
+
+ for (UnlockFunctionAttr::args_iterator I = UFAttr->args_begin(),
+ E = UFAttr->args_end(); I != E; ++I)
+ removeLock(ExpLocation, *I);
+ break;
+ }
+
+ case attr::ExclusiveLocksRequired: {
+ // FIXME: Also use this attribute to add required locks to the initial
+ // lockset when processing a CFG for a function annotated with this
+ // attribute.
+ ExclusiveLocksRequiredAttr *ELRAttr =
+ cast<ExclusiveLocksRequiredAttr>(Attr);
+
+ for (ExclusiveLocksRequiredAttr::args_iterator
+ I = ELRAttr->args_begin(), E = ELRAttr->args_end(); I != E; ++I)
+ warnIfMutexNotHeld(D, Exp, AK_Written, *I, POK_FunctionCall);
+ break;
+ }
+
+ case attr::SharedLocksRequired: {
+ // FIXME: Also use this attribute to add required locks to the initial
+ // lockset when processing a CFG for a function annotated with this
+ // attribute.
+ SharedLocksRequiredAttr *SLRAttr = cast<SharedLocksRequiredAttr>(Attr);
+
+ for (SharedLocksRequiredAttr::args_iterator I = SLRAttr->args_begin(),
+ E = SLRAttr->args_end(); I != E; ++I)
+ warnIfMutexNotHeld(D, Exp, AK_Read, *I, POK_FunctionCall);
+ break;
+ }
+
+ case attr::LocksExcluded: {
+ LocksExcludedAttr *LEAttr = cast<LocksExcludedAttr>(Attr);
+ for (LocksExcludedAttr::args_iterator I = LEAttr->args_begin(),
+ E = LEAttr->args_end(); I != E; ++I) {
+ MutexID Mutex(*I);
+ if (locksetContains(Mutex))
+ Handler.handleFunExcludesLock(D->getName(), Mutex.getName(),
+ ExpLocation);
+ }
+ break;
+ }
+
+ case attr::LockReturned:
+ // FIXME: Deal with this attribute.
+ break;
+
+ // Ignore other (non thread-safety) attributes
+ default:
+ break;
+ }
+ }
+}
+
+} // end anonymous namespace
+
+/// \brief Flags a warning for each lock that is in LSet2 but not LSet1, or
+/// else mutexes that are held shared in one lockset and exclusive in the other.
+static Lockset warnIfNotInFirstSetOrNotSameKind(ThreadSafetyHandler &Handler,
+ const Lockset LSet1,
+ const Lockset LSet2,
+ Lockset Intersection,
+ Lockset::Factory &Fact) {
+ for (Lockset::iterator I = LSet2.begin(), E = LSet2.end(); I != E; ++I) {
+ const MutexID &LSet2Mutex = I.getKey();
+ const LockData &LSet2LockData = I.getData();
+ if (const LockData *LD = LSet1.lookup(LSet2Mutex)) {
+ if (LD->LKind != LSet2LockData.LKind) {
+ Handler.handleExclusiveAndShared(LSet2Mutex.getName(),
+ LSet2LockData.AcquireLoc,
+ LD->AcquireLoc);
+ if (LD->LKind != LK_Exclusive)
+ Intersection = Fact.add(Intersection, LSet2Mutex, LSet2LockData);
+ }
+ } else {
+ Handler.handleMutexHeldEndOfScope(LSet2Mutex.getName(),
+ LSet2LockData.AcquireLoc);
+ }
+ }
+ return Intersection;
+}
+
+
+/// \brief Compute the intersection of two locksets and issue warnings for any
+/// locks in the symmetric difference.
+///
+/// This function is used at a merge point in the CFG when comparing the lockset
+/// of each branch being merged. For example, given the following sequence:
+/// A; if () then B; else C; D; we need to check that the lockset after B and C
+/// are the same. In the event of a difference, we use the intersection of these
+/// two locksets at the start of D.
+static Lockset intersectAndWarn(ThreadSafetyHandler &Handler,
+ const Lockset LSet1, const Lockset LSet2,
+ Lockset::Factory &Fact) {
+ Lockset Intersection = LSet1;
+ Intersection = warnIfNotInFirstSetOrNotSameKind(Handler, LSet1, LSet2,
+ Intersection, Fact);
+
+ for (Lockset::iterator I = LSet1.begin(), E = LSet1.end(); I != E; ++I) {
+ if (!LSet2.contains(I.getKey())) {
+ const MutexID &Mutex = I.getKey();
+ const LockData &MissingLock = I.getData();
+ Handler.handleMutexHeldEndOfScope(Mutex.getName(),
+ MissingLock.AcquireLoc);
+ Intersection = Fact.remove(Intersection, Mutex);
+ }
+ }
+ return Intersection;
+}
+
+/// \brief Returns the location of the first Stmt in a Block.
+static SourceLocation getFirstStmtLocation(CFGBlock *Block) {
+ SourceLocation Loc;
+ for (CFGBlock::const_iterator BI = Block->begin(), BE = Block->end();
+ BI != BE; ++BI) {
+ if (const CFGStmt *CfgStmt = dyn_cast<CFGStmt>(&(*BI))) {
+ Loc = CfgStmt->getStmt()->getLocStart();
+ if (Loc.isValid()) return Loc;
+ }
+ }
+ if (Stmt *S = Block->getTerminator().getStmt()) {
+ Loc = S->getLocStart();
+ if (Loc.isValid()) return Loc;
+ }
+ return Loc;
+}
+
+/// \brief Warn about different locksets along backedges of loops.
+/// This function is called when we encounter a back edge. At that point,
+/// we need to verify that the lockset before taking the backedge is the
+/// same as the lockset before entering the loop.
+///
+/// \param LoopEntrySet Locks before starting the loop
+/// \param LoopReentrySet Locks in the last CFG block of the loop
+static void warnBackEdgeUnequalLocksets(ThreadSafetyHandler &Handler,
+ const Lockset LoopReentrySet,
+ const Lockset LoopEntrySet,
+ SourceLocation FirstLocInLoop,
+ Lockset::Factory &Fact) {
+ assert(FirstLocInLoop.isValid());
+ // Warn for locks held at the start of the loop, but not the end.
+ for (Lockset::iterator I = LoopEntrySet.begin(), E = LoopEntrySet.end();
+ I != E; ++I) {
+ if (!LoopReentrySet.contains(I.getKey())) {
+ // We report this error at the location of the first statement in a loop
+ Handler.handleNoLockLoopEntry(I.getKey().getName(), FirstLocInLoop);
+ }
+ }
+
+ // Warn for locks held at the end of the loop, but not at the start.
+ warnIfNotInFirstSetOrNotSameKind(Handler, LoopEntrySet, LoopReentrySet,
+ LoopReentrySet, Fact);
+}
+
+
+namespace clang { namespace thread_safety {
+/// \brief Check a function's CFG for thread-safety violations.
+///
+/// We traverse the blocks in the CFG, compute the set of mutexes that are held
+/// at the end of each block, and issue warnings for thread safety violations.
+/// Each block in the CFG is traversed exactly once.
+void runThreadSafetyAnalysis(AnalysisContext &AC,
+ ThreadSafetyHandler &Handler) {
+ CFG *CFGraph = AC.getCFG();
+ if (!CFGraph) return;
+ const Decl *D = AC.getDecl();
+ if (D && D->getAttr<NoThreadSafetyAnalysisAttr>()) return;
+
+ Lockset::Factory LocksetFactory;
+
+ // FIXME: Swith to SmallVector? Otherwise improve performance impact?
+ std::vector<Lockset> EntryLocksets(CFGraph->getNumBlockIDs(),
+ LocksetFactory.getEmptyMap());
+ std::vector<Lockset> ExitLocksets(CFGraph->getNumBlockIDs(),
+ LocksetFactory.getEmptyMap());
+
+ // We need to explore the CFG via a "topological" ordering.
+ // That way, we will be guaranteed to have information about required
+ // predecessor locksets when exploring a new block.
+ TopologicallySortedCFG SortedGraph(CFGraph);
+ CFGBlockSet VisitedBlocks(CFGraph);
+
+ for (TopologicallySortedCFG::iterator I = SortedGraph.begin(),
+ E = SortedGraph.end(); I!= E; ++I) {
+ const CFGBlock *CurrBlock = *I;
+ int CurrBlockID = CurrBlock->getBlockID();
+
+ VisitedBlocks.insert(CurrBlock);
+
+ // Use the default initial lockset in case there are no predecessors.
+ Lockset &Entryset = EntryLocksets[CurrBlockID];
+ Lockset &Exitset = ExitLocksets[CurrBlockID];
+
+ // Iterate through the predecessor blocks and warn if the lockset for all
+ // predecessors is not the same. We take the entry lockset of the current
+ // block to be the intersection of all previous locksets.
+ // FIXME: By keeping the intersection, we may output more errors in future
+ // for a lock which is not in the intersection, but was in the union. We
+ // may want to also keep the union in future. As an example, let's say
+ // the intersection contains Mutex L, and the union contains L and M.
+ // Later we unlock M. At this point, we would output an error because we
+ // never locked M; although the real error is probably that we forgot to
+ // lock M on all code paths. Conversely, let's say that later we lock M.
+ // In this case, we should compare against the intersection instead of the
+ // union because the real error is probably that we forgot to unlock M on
+ // all code paths.
+ bool LocksetInitialized = false;
+ for (CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
+ PE = CurrBlock->pred_end(); PI != PE; ++PI) {
+
+ // if *PI -> CurrBlock is a back edge
+ if (*PI == 0 || !VisitedBlocks.alreadySet(*PI))
+ continue;
+
+ int PrevBlockID = (*PI)->getBlockID();
+ if (!LocksetInitialized) {
+ Entryset = ExitLocksets[PrevBlockID];
+ LocksetInitialized = true;
+ } else {
+ Entryset = intersectAndWarn(Handler, Entryset,
+ ExitLocksets[PrevBlockID], LocksetFactory);
+ }
+ }
+
+ BuildLockset LocksetBuilder(Handler, Entryset, LocksetFactory);
+ for (CFGBlock::const_iterator BI = CurrBlock->begin(),
+ BE = CurrBlock->end(); BI != BE; ++BI) {
+ if (const CFGStmt *CfgStmt = dyn_cast<CFGStmt>(&*BI))
+ LocksetBuilder.Visit(const_cast<Stmt*>(CfgStmt->getStmt()));
+ }
+ Exitset = LocksetBuilder.getLockset();
+
+ // For every back edge from CurrBlock (the end of the loop) to another block
+ // (FirstLoopBlock) we need to check that the Lockset of Block is equal to
+ // the one held at the beginning of FirstLoopBlock. We can look up the
+ // Lockset held at the beginning of FirstLoopBlock in the EntryLockSets map.
+ for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
+ SE = CurrBlock->succ_end(); SI != SE; ++SI) {
+
+ // if CurrBlock -> *SI is *not* a back edge
+ if (*SI == 0 || !VisitedBlocks.alreadySet(*SI))
+ continue;
+
+ CFGBlock *FirstLoopBlock = *SI;
+ SourceLocation FirstLoopLocation = getFirstStmtLocation(FirstLoopBlock);
+
+ assert(FirstLoopLocation.isValid());
+
+ // Fail gracefully in release code.
+ if (!FirstLoopLocation.isValid())
+ continue;
+
+ Lockset PreLoop = EntryLocksets[FirstLoopBlock->getBlockID()];
+ Lockset LoopEnd = ExitLocksets[CurrBlockID];
+ warnBackEdgeUnequalLocksets(Handler, LoopEnd, PreLoop, FirstLoopLocation,
+ LocksetFactory);
+ }
+ }
+
+ Lockset FinalLockset = ExitLocksets[CFGraph->getExit().getBlockID()];
+ if (!FinalLockset.isEmpty()) {
+ for (Lockset::iterator I=FinalLockset.begin(), E=FinalLockset.end();
+ I != E; ++I) {
+ const MutexID &Mutex = I.getKey();
+ const LockData &MissingLock = I.getData();
+
+ std::string FunName = "<unknown>";
+ if (const NamedDecl *ContextDecl = dyn_cast<NamedDecl>(AC.getDecl())) {
+ FunName = ContextDecl->getDeclName().getAsString();
+ }
+
+ Handler.handleNoUnlock(Mutex.getName(), FunName, MissingLock.AcquireLoc);
+ }
+ }
+}
+
+/// \brief Helper function that returns a LockKind required for the given level
+/// of access.
+LockKind getLockKindFromAccessKind(AccessKind AK) {
+ switch (AK) {
+ case AK_Read :
+ return LK_Shared;
+ case AK_Written :
+ return LK_Exclusive;
+ }
+}
+}} // end namespace clang::thread_safety
#include "clang/Analysis/CFG.h"
#include "clang/Analysis/Analyses/ReachableCode.h"
#include "clang/Analysis/Analyses/CFGReachabilityAnalysis.h"
+#include "clang/Analysis/Analyses/ThreadSafety.h"
#include "clang/Analysis/CFGStmtMap.h"
#include "clang/Analysis/Analyses/UninitializedValues.h"
#include "llvm/ADT/BitVector.h"
typedef std::pair<SourceLocation, PartialDiagnostic> DelayedDiag;
typedef llvm::SmallVector<DelayedDiag, 4> DiagList;
-enum ProtectedOperationKind {
- POK_VarDereference,
- POK_VarAccess,
- POK_FunctionCall
-};
-
-enum LockKind {
- LK_Shared,
- LK_Exclusive
-};
-
-enum AccessKind {
- AK_Read,
- AK_Written
-};
-
-
struct SortDiagBySourceLocation {
Sema &S;
SortDiagBySourceLocation(Sema &S) : S(S) {}
}
};
-/// \brief Helper function that returns a LockKind required for the given level
-/// of access.
-LockKind getLockKindFromAccessKind(AccessKind AK) {
- switch (AK) {
- case AK_Read :
- return LK_Shared;
- case AK_Written :
- return LK_Exclusive;
- }
-}
-
-class ThreadSafetyHandler {
-public:
- typedef llvm::StringRef Name;
- ThreadSafetyHandler() {}
- virtual ~ThreadSafetyHandler() {}
- virtual void handleUnmatchedUnlock(Name LockName, SourceLocation Loc) {}
- virtual void handleDoubleLock(Name LockName, SourceLocation Loc) {}
- virtual void handleMutexHeldEndOfScope(Name LockName, SourceLocation Loc){}
- virtual void handleNoLockLoopEntry(Name LockName, SourceLocation Loc) {}
- virtual void handleNoUnlock(Name LockName, Name FunName,
- SourceLocation Loc) {}
- virtual void handleExclusiveAndShared(Name LockName, SourceLocation Loc1,
- SourceLocation Loc2) {}
- virtual void handleNoMutexHeld(const NamedDecl *D, ProtectedOperationKind POK,
- AccessKind AK, SourceLocation Loc) {}
- virtual void handleMutexNotHeld(const NamedDecl *D,
- ProtectedOperationKind POK, Name LockName,
- LockKind LK, SourceLocation Loc) {}
- virtual void handleFunExcludesLock(Name FunName, Name LockName,
- SourceLocation Loc) {}
-};
-
class ThreadSafetyReporter : public clang::thread_safety::ThreadSafetyHandler {
Sema &S;
DiagList Warnings;
}
}
-using namespace thread_safety;
-
-namespace {
-/// \brief Implements a set of CFGBlocks using a BitVector.
-///
-/// This class contains a minimal interface, primarily dictated by the SetType
-/// template parameter of the llvm::po_iterator template, as used with external
-/// storage. We also use this set to keep track of which CFGBlocks we visit
-/// during the analysis.
-class CFGBlockSet {
- llvm::BitVector VisitedBlockIDs;
-
-public:
- // po_iterator requires this iterator, but the only interface needed is the
- // value_type typedef.
- struct iterator {
- typedef const CFGBlock *value_type;
- };
-
- CFGBlockSet() {}
- CFGBlockSet(const CFG *G) : VisitedBlockIDs(G->getNumBlockIDs(), false) {}
-
- /// \brief Set the bit associated with a particular CFGBlock.
- /// This is the important method for the SetType template parameter.
- bool insert(const CFGBlock *Block) {
- // Note that insert() is called by po_iterator, which doesn't check to make
- // sure that Block is non-null. Moreover, the CFGBlock iterator will
- // occasionally hand out null pointers for pruned edges, so we catch those
- // here.
- if (Block == 0)
- return false; // if an edge is trivially false.
- if (VisitedBlockIDs.test(Block->getBlockID()))
- return false;
- VisitedBlockIDs.set(Block->getBlockID());
- return true;
- }
-
- /// \brief Check if the bit for a CFGBlock has been already set.
- /// This method is for tracking visited blocks in the main threadsafety loop.
- /// Block must not be null.
- bool alreadySet(const CFGBlock *Block) {
- return VisitedBlockIDs.test(Block->getBlockID());
- }
-};
-
-/// \brief We create a helper class which we use to iterate through CFGBlocks in
-/// the topological order.
-class TopologicallySortedCFG {
- typedef llvm::po_iterator<const CFG*, CFGBlockSet, true> po_iterator;
-
- std::vector<const CFGBlock*> Blocks;
-
-public:
- typedef std::vector<const CFGBlock*>::reverse_iterator iterator;
-
- TopologicallySortedCFG(const CFG *CFGraph) {
- Blocks.reserve(CFGraph->getNumBlockIDs());
- CFGBlockSet BSet(CFGraph);
-
- for (po_iterator I = po_iterator::begin(CFGraph, BSet),
- E = po_iterator::end(CFGraph, BSet); I != E; ++I) {
- Blocks.push_back(*I);
- }
- }
-
- iterator begin() {
- return Blocks.rbegin();
- }
-
- iterator end() {
- return Blocks.rend();
- }
-};
-
-/// \brief A MutexID object uniquely identifies a particular mutex, and
-/// is built from an Expr* (i.e. calling a lock function).
-///
-/// Thread-safety analysis works by comparing lock expressions. Within the
-/// body of a function, an expression such as "x->foo->bar.mu" will resolve to
-/// a particular mutex object at run-time. Subsequent occurrences of the same
-/// expression (where "same" means syntactic equality) will refer to the same
-/// run-time object if three conditions hold:
-/// (1) Local variables in the expression, such as "x" have not changed.
-/// (2) Values on the heap that affect the expression have not changed.
-/// (3) The expression involves only pure function calls.
-/// The current implementation assumes, but does not verify, that multiple uses
-/// of the same lock expression satisfies these criteria.
-///
-/// Clang introduces an additional wrinkle, which is that it is difficult to
-/// derive canonical expressions, or compare expressions directly for equality.
-/// Thus, we identify a mutex not by an Expr, but by the set of named
-/// declarations that are referenced by the Expr. In other words,
-/// x->foo->bar.mu will be a four element vector with the Decls for
-/// mu, bar, and foo, and x. The vector will uniquely identify the expression
-/// for all practical purposes.
-///
-/// Note we will need to perform substitution on "this" and function parameter
-/// names when constructing a lock expression.
-///
-/// For example:
-/// class C { Mutex Mu; void lock() EXCLUSIVE_LOCK_FUNCTION(this->Mu); };
-/// void myFunc(C *X) { ... X->lock() ... }
-/// The original expression for the mutex acquired by myFunc is "this->Mu", but
-/// "X" is substituted for "this" so we get X->Mu();
-///
-/// For another example:
-/// foo(MyList *L) EXCLUSIVE_LOCKS_REQUIRED(L->Mu) { ... }
-/// MyList *MyL;
-/// foo(MyL); // requires lock MyL->Mu to be held
-class MutexID {
- SmallVector<NamedDecl*, 2> DeclSeq;
-
- /// Build a Decl sequence representing the lock from the given expression.
- /// Recursive function that bottoms out when the final DeclRefExpr is reached.
- void buildMutexID(Expr *Exp) {
- if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Exp)) {
- NamedDecl *ND = cast<NamedDecl>(DRE->getDecl()->getCanonicalDecl());
- DeclSeq.push_back(ND);
- } else if (MemberExpr *ME = dyn_cast<MemberExpr>(Exp)) {
- NamedDecl *ND = ME->getMemberDecl();
- DeclSeq.push_back(ND);
- buildMutexID(ME->getBase());
- } else if (isa<CXXThisExpr>(Exp)) {
- return;
- } else {
- // FIXME: add diagnostic
- llvm::report_fatal_error("Expected lock expression!");
- }
- }
-
-public:
- MutexID(Expr *LExpr) {
- buildMutexID(LExpr);
- assert(!DeclSeq.empty());
- }
-
- bool operator==(const MutexID &other) const {
- return DeclSeq == other.DeclSeq;
- }
-
- bool operator!=(const MutexID &other) const {
- return !(*this == other);
- }
-
- // SmallVector overloads Operator< to do lexicographic ordering. Note that
- // we use pointer equality (and <) to compare NamedDecls. This means the order
- // of MutexIDs in a lockset is nondeterministic. In order to output
- // diagnostics in a deterministic ordering, we must order all diagnostics to
- // output by SourceLocation when iterating through this lockset.
- bool operator<(const MutexID &other) const {
- return DeclSeq < other.DeclSeq;
- }
-
- /// \brief Returns the name of the first Decl in the list for a given MutexID;
- /// e.g. the lock expression foo.bar() has name "bar".
- /// The caret will point unambiguously to the lock expression, so using this
- /// name in diagnostics is a way to get simple, and consistent, mutex names.
- /// We do not want to output the entire expression text for security reasons.
- StringRef getName() const {
- return DeclSeq.front()->getName();
- }
-
- void Profile(llvm::FoldingSetNodeID &ID) const {
- for (SmallVectorImpl<NamedDecl*>::const_iterator I = DeclSeq.begin(),
- E = DeclSeq.end(); I != E; ++I) {
- ID.AddPointer(*I);
- }
- }
-};
-
-/// \brief This is a helper class that stores info about the most recent
-/// accquire of a Lock.
-///
-/// The main body of the analysis maps MutexIDs to LockDatas.
-struct LockData {
- SourceLocation AcquireLoc;
-
- /// \brief LKind stores whether a lock is held shared or exclusively.
- /// Note that this analysis does not currently support either re-entrant
- /// locking or lock "upgrading" and "downgrading" between exclusive and
- /// shared.
- ///
- /// FIXME: add support for re-entrant locking and lock up/downgrading
- LockKind LKind;
-
- LockData(SourceLocation AcquireLoc, LockKind LKind)
- : AcquireLoc(AcquireLoc), LKind(LKind) {}
-
- bool operator==(const LockData &other) const {
- return AcquireLoc == other.AcquireLoc && LKind == other.LKind;
- }
-
- bool operator!=(const LockData &other) const {
- return !(*this == other);
- }
-
- void Profile(llvm::FoldingSetNodeID &ID) const {
- ID.AddInteger(AcquireLoc.getRawEncoding());
- ID.AddInteger(LKind);
- }
-};
-
-/// A Lockset maps each MutexID (defined above) to information about how it has
-/// been locked.
-typedef llvm::ImmutableMap<MutexID, LockData> Lockset;
-
-/// \brief We use this class to visit different types of expressions in
-/// CFGBlocks, and build up the lockset.
-/// An expression may cause us to add or remove locks from the lockset, or else
-/// output error messages related to missing locks.
-/// FIXME: In future, we may be able to not inherit from a visitor.
-class BuildLockset : public StmtVisitor<BuildLockset> {
- ThreadSafetyHandler &Handler;
- Lockset LSet;
- Lockset::Factory &LocksetFactory;
-
- // Helper functions
- void removeLock(SourceLocation UnlockLoc, Expr *LockExp);
- void addLock(SourceLocation LockLoc, Expr *LockExp, LockKind LK);
- const ValueDecl *getValueDecl(Expr *Exp);
- void warnIfMutexNotHeld (const NamedDecl *D, Expr *Exp, AccessKind AK,
- Expr *MutexExp, ProtectedOperationKind POK);
- void checkAccess(Expr *Exp, AccessKind AK);
- void checkDereference(Expr *Exp, AccessKind AK);
-
- template <class AttrType>
- void addLocksToSet(LockKind LK, Attr *Attr, CXXMemberCallExpr *Exp);
-
- /// \brief Returns true if the lockset contains a lock, regardless of whether
- /// the lock is held exclusively or shared.
- bool locksetContains(MutexID Lock) const {
- return LSet.lookup(Lock);
- }
-
- /// \brief Returns true if the lockset contains a lock with the passed in
- /// locktype.
- bool locksetContains(MutexID Lock, LockKind KindRequested) const {
- const LockData *LockHeld = LSet.lookup(Lock);
- return (LockHeld && KindRequested == LockHeld->LKind);
- }
-
- /// \brief Returns true if the lockset contains a lock with at least the
- /// passed in locktype. So for example, if we pass in LK_Shared, this function
- /// returns true if the lock is held LK_Shared or LK_Exclusive. If we pass in
- /// LK_Exclusive, this function returns true if the lock is held LK_Exclusive.
- bool locksetContainsAtLeast(MutexID Lock, LockKind KindRequested) const {
- switch (KindRequested) {
- case LK_Shared:
- return locksetContains(Lock);
- case LK_Exclusive:
- return locksetContains(Lock, KindRequested);
- }
- }
-
-public:
- BuildLockset(ThreadSafetyHandler &Handler, Lockset LS, Lockset::Factory &F)
- : StmtVisitor<BuildLockset>(), Handler(Handler), LSet(LS),
- LocksetFactory(F) {}
-
- Lockset getLockset() {
- return LSet;
- }
-
- void VisitUnaryOperator(UnaryOperator *UO);
- void VisitBinaryOperator(BinaryOperator *BO);
- void VisitCastExpr(CastExpr *CE);
- void VisitCXXMemberCallExpr(CXXMemberCallExpr *Exp);
-};
-
-/// \brief Add a new lock to the lockset, warning if the lock is already there.
-/// \param LockLoc The source location of the acquire
-/// \param LockExp The lock expression corresponding to the lock to be added
-void BuildLockset::addLock(SourceLocation LockLoc, Expr *LockExp,
- LockKind LK) {
- // FIXME: deal with acquired before/after annotations
- MutexID Mutex(LockExp);
- LockData NewLock(LockLoc, LK);
-
- // FIXME: Don't always warn when we have support for reentrant locks.
- if (locksetContains(Mutex))
- Handler.handleDoubleLock(Mutex.getName(), LockLoc);
- LSet = LocksetFactory.add(LSet, Mutex, NewLock);
-}
-
-/// \brief Remove a lock from the lockset, warning if the lock is not there.
-/// \param LockExp The lock expression corresponding to the lock to be removed
-/// \param UnlockLoc The source location of the unlock (only used in error msg)
-void BuildLockset::removeLock(SourceLocation UnlockLoc, Expr *LockExp) {
- MutexID Mutex(LockExp);
-
- Lockset NewLSet = LocksetFactory.remove(LSet, Mutex);
- if(NewLSet == LSet)
- Handler.handleUnmatchedUnlock(Mutex.getName(), UnlockLoc);
-
- LSet = NewLSet;
-}
-
-/// \brief Gets the value decl pointer from DeclRefExprs or MemberExprs
-const ValueDecl *BuildLockset::getValueDecl(Expr *Exp) {
- if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Exp))
- return DR->getDecl();
-
- if (const MemberExpr *ME = dyn_cast<MemberExpr>(Exp))
- return ME->getMemberDecl();
-
- return 0;
-}
-
-/// \brief Warn if the LSet does not contain a lock sufficient to protect access
-/// of at least the passed in AccessType.
-void BuildLockset::warnIfMutexNotHeld(const NamedDecl *D, Expr *Exp,
- AccessKind AK, Expr *MutexExp,
- ProtectedOperationKind POK) {
- LockKind LK = getLockKindFromAccessKind(AK);
- MutexID Mutex(MutexExp);
- if (!locksetContainsAtLeast(Mutex, LK))
- Handler.handleMutexNotHeld(D, POK, Mutex.getName(), LK, Exp->getExprLoc());
-}
-
-
-/// \brief This method identifies variable dereferences and checks pt_guarded_by
-/// and pt_guarded_var annotations. Note that we only check these annotations
-/// at the time a pointer is dereferenced.
-/// FIXME: We need to check for other types of pointer dereferences
-/// (e.g. [], ->) and deal with them here.
-/// \param Exp An expression that has been read or written.
-void BuildLockset::checkDereference(Expr *Exp, AccessKind AK) {
- UnaryOperator *UO = dyn_cast<UnaryOperator>(Exp);
- if (!UO || UO->getOpcode() != clang::UO_Deref)
- return;
- Exp = UO->getSubExpr()->IgnoreParenCasts();
-
- const ValueDecl *D = getValueDecl(Exp);
- if(!D || !D->hasAttrs())
- return;
-
- if (D->getAttr<PtGuardedVarAttr>() && LSet.isEmpty())
- Handler.handleNoMutexHeld(D, POK_VarDereference, AK, Exp->getExprLoc());
-
- const AttrVec &ArgAttrs = D->getAttrs();
- for(unsigned i = 0, Size = ArgAttrs.size(); i < Size; ++i)
- if (PtGuardedByAttr *PGBAttr = dyn_cast<PtGuardedByAttr>(ArgAttrs[i]))
- warnIfMutexNotHeld(D, Exp, AK, PGBAttr->getArg(), POK_VarDereference);
-}
-
-/// \brief Checks guarded_by and guarded_var attributes.
-/// Whenever we identify an access (read or write) of a DeclRefExpr or
-/// MemberExpr, we need to check whether there are any guarded_by or
-/// guarded_var attributes, and make sure we hold the appropriate mutexes.
-void BuildLockset::checkAccess(Expr *Exp, AccessKind AK) {
- const ValueDecl *D = getValueDecl(Exp);
- if(!D || !D->hasAttrs())
- return;
-
- if (D->getAttr<GuardedVarAttr>() && LSet.isEmpty())
- Handler.handleNoMutexHeld(D, POK_VarAccess, AK, Exp->getExprLoc());
-
- const AttrVec &ArgAttrs = D->getAttrs();
- for(unsigned i = 0, Size = ArgAttrs.size(); i < Size; ++i)
- if (GuardedByAttr *GBAttr = dyn_cast<GuardedByAttr>(ArgAttrs[i]))
- warnIfMutexNotHeld(D, Exp, AK, GBAttr->getArg(), POK_VarAccess);
-}
-
-/// \brief For unary operations which read and write a variable, we need to
-/// check whether we hold any required mutexes. Reads are checked in
-/// VisitCastExpr.
-void BuildLockset::VisitUnaryOperator(UnaryOperator *UO) {
- switch (UO->getOpcode()) {
- case clang::UO_PostDec:
- case clang::UO_PostInc:
- case clang::UO_PreDec:
- case clang::UO_PreInc: {
- Expr *SubExp = UO->getSubExpr()->IgnoreParenCasts();
- checkAccess(SubExp, AK_Written);
- checkDereference(SubExp, AK_Written);
- break;
- }
- default:
- break;
- }
-}
-
-/// For binary operations which assign to a variable (writes), we need to check
-/// whether we hold any required mutexes.
-/// FIXME: Deal with non-primitive types.
-void BuildLockset::VisitBinaryOperator(BinaryOperator *BO) {
- if (!BO->isAssignmentOp())
- return;
- Expr *LHSExp = BO->getLHS()->IgnoreParenCasts();
- checkAccess(LHSExp, AK_Written);
- checkDereference(LHSExp, AK_Written);
-}
-
-/// Whenever we do an LValue to Rvalue cast, we are reading a variable and
-/// need to ensure we hold any required mutexes.
-/// FIXME: Deal with non-primitive types.
-void BuildLockset::VisitCastExpr(CastExpr *CE) {
- if (CE->getCastKind() != CK_LValueToRValue)
- return;
- Expr *SubExp = CE->getSubExpr()->IgnoreParenCasts();
- checkAccess(SubExp, AK_Read);
- checkDereference(SubExp, AK_Read);
-}
-
-/// \brief This function, parameterized by an attribute type, is used to add a
-/// set of locks specified as attribute arguments to the lockset.
-template <typename AttrType>
-void BuildLockset::addLocksToSet(LockKind LK, Attr *Attr,
- CXXMemberCallExpr *Exp) {
- typedef typename AttrType::args_iterator iterator_type;
- SourceLocation ExpLocation = Exp->getExprLoc();
- Expr *Parent = Exp->getImplicitObjectArgument();
- AttrType *SpecificAttr = cast<AttrType>(Attr);
-
- if (SpecificAttr->args_size() == 0) {
- // The mutex held is the "this" object.
- addLock(ExpLocation, Parent, LK);
- return;
- }
-
- for (iterator_type I = SpecificAttr->args_begin(),
- E = SpecificAttr->args_end(); I != E; ++I)
- addLock(ExpLocation, *I, LK);
-}
-
-/// \brief When visiting CXXMemberCallExprs we need to examine the attributes on
-/// the method that is being called and add, remove or check locks in the
-/// lockset accordingly.
-///
-/// FIXME: For classes annotated with one of the guarded annotations, we need
-/// to treat const method calls as reads and non-const method calls as writes,
-/// and check that the appropriate locks are held. Non-const method calls with
-/// the same signature as const method calls can be also treated as reads.
-///
-/// FIXME: We need to also visit CallExprs to catch/check global functions.
-void BuildLockset::VisitCXXMemberCallExpr(CXXMemberCallExpr *Exp) {
- NamedDecl *D = dyn_cast_or_null<NamedDecl>(Exp->getCalleeDecl());
-
- SourceLocation ExpLocation = Exp->getExprLoc();
- Expr *Parent = Exp->getImplicitObjectArgument();
-
- if(!D || !D->hasAttrs())
- return;
-
- AttrVec &ArgAttrs = D->getAttrs();
- for(unsigned i = 0; i < ArgAttrs.size(); ++i) {
- Attr *Attr = ArgAttrs[i];
- switch (Attr->getKind()) {
- // When we encounter an exclusive lock function, we need to add the lock
- // to our lockset with kind exclusive.
- case attr::ExclusiveLockFunction:
- addLocksToSet<ExclusiveLockFunctionAttr>(LK_Exclusive, Attr, Exp);
- break;
-
- // When we encounter a shared lock function, we need to add the lock
- // to our lockset with kind shared.
- case attr::SharedLockFunction:
- addLocksToSet<SharedLockFunctionAttr>(LK_Shared, Attr, Exp);
- break;
-
- // When we encounter an unlock function, we need to remove unlocked
- // mutexes from the lockset, and flag a warning if they are not there.
- case attr::UnlockFunction: {
- UnlockFunctionAttr *UFAttr = cast<UnlockFunctionAttr>(Attr);
-
- if (UFAttr->args_size() == 0) { // The lock held is the "this" object.
- removeLock(ExpLocation, Parent);
- break;
- }
-
- for (UnlockFunctionAttr::args_iterator I = UFAttr->args_begin(),
- E = UFAttr->args_end(); I != E; ++I)
- removeLock(ExpLocation, *I);
- break;
- }
-
- case attr::ExclusiveLocksRequired: {
- // FIXME: Also use this attribute to add required locks to the initial
- // lockset when processing a CFG for a function annotated with this
- // attribute.
- ExclusiveLocksRequiredAttr *ELRAttr =
- cast<ExclusiveLocksRequiredAttr>(Attr);
-
- for (ExclusiveLocksRequiredAttr::args_iterator
- I = ELRAttr->args_begin(), E = ELRAttr->args_end(); I != E; ++I)
- warnIfMutexNotHeld(D, Exp, AK_Written, *I, POK_FunctionCall);
- break;
- }
-
- case attr::SharedLocksRequired: {
- // FIXME: Also use this attribute to add required locks to the initial
- // lockset when processing a CFG for a function annotated with this
- // attribute.
- SharedLocksRequiredAttr *SLRAttr = cast<SharedLocksRequiredAttr>(Attr);
-
- for (SharedLocksRequiredAttr::args_iterator I = SLRAttr->args_begin(),
- E = SLRAttr->args_end(); I != E; ++I)
- warnIfMutexNotHeld(D, Exp, AK_Read, *I, POK_FunctionCall);
- break;
- }
-
- case attr::LocksExcluded: {
- LocksExcludedAttr *LEAttr = cast<LocksExcludedAttr>(Attr);
- for (LocksExcludedAttr::args_iterator I = LEAttr->args_begin(),
- E = LEAttr->args_end(); I != E; ++I) {
- MutexID Mutex(*I);
- if (locksetContains(Mutex))
- Handler.handleFunExcludesLock(D->getName(), Mutex.getName(),
- ExpLocation);
- }
- break;
- }
-
- case attr::LockReturned:
- // FIXME: Deal with this attribute.
- break;
-
- // Ignore other (non thread-safety) attributes
- default:
- break;
- }
- }
-}
-
-} // end anonymous namespace
-
-/// \brief Flags a warning for each lock that is in LSet2 but not LSet1, or
-/// else mutexes that are held shared in one lockset and exclusive in the other.
-static Lockset warnIfNotInFirstSetOrNotSameKind(ThreadSafetyHandler &Handler,
- const Lockset LSet1,
- const Lockset LSet2,
- Lockset Intersection,
- Lockset::Factory &Fact) {
- for (Lockset::iterator I = LSet2.begin(), E = LSet2.end(); I != E; ++I) {
- const MutexID &LSet2Mutex = I.getKey();
- const LockData &LSet2LockData = I.getData();
- if (const LockData *LD = LSet1.lookup(LSet2Mutex)) {
- if (LD->LKind != LSet2LockData.LKind) {
- Handler.handleExclusiveAndShared(LSet2Mutex.getName(),
- LSet2LockData.AcquireLoc,
- LD->AcquireLoc);
- if (LD->LKind != LK_Exclusive)
- Intersection = Fact.add(Intersection, LSet2Mutex, LSet2LockData);
- }
- } else {
- Handler.handleMutexHeldEndOfScope(LSet2Mutex.getName(),
- LSet2LockData.AcquireLoc);
- }
- }
- return Intersection;
-}
-
-
-/// \brief Compute the intersection of two locksets and issue warnings for any
-/// locks in the symmetric difference.
-///
-/// This function is used at a merge point in the CFG when comparing the lockset
-/// of each branch being merged. For example, given the following sequence:
-/// A; if () then B; else C; D; we need to check that the lockset after B and C
-/// are the same. In the event of a difference, we use the intersection of these
-/// two locksets at the start of D.
-static Lockset intersectAndWarn(ThreadSafetyHandler &Handler,
- const Lockset LSet1, const Lockset LSet2,
- Lockset::Factory &Fact) {
- Lockset Intersection = LSet1;
- Intersection = warnIfNotInFirstSetOrNotSameKind(Handler, LSet1, LSet2,
- Intersection, Fact);
-
- for (Lockset::iterator I = LSet1.begin(), E = LSet1.end(); I != E; ++I) {
- if (!LSet2.contains(I.getKey())) {
- const MutexID &Mutex = I.getKey();
- const LockData &MissingLock = I.getData();
- Handler.handleMutexHeldEndOfScope(Mutex.getName(),
- MissingLock.AcquireLoc);
- Intersection = Fact.remove(Intersection, Mutex);
- }
- }
- return Intersection;
-}
-
-/// \brief Returns the location of the first Stmt in a Block.
-static SourceLocation getFirstStmtLocation(CFGBlock *Block) {
- SourceLocation Loc;
- for (CFGBlock::const_iterator BI = Block->begin(), BE = Block->end();
- BI != BE; ++BI) {
- if (const CFGStmt *CfgStmt = dyn_cast<CFGStmt>(&(*BI))) {
- Loc = CfgStmt->getStmt()->getLocStart();
- if (Loc.isValid()) return Loc;
- }
- }
- if (Stmt *S = Block->getTerminator().getStmt()) {
- Loc = S->getLocStart();
- if (Loc.isValid()) return Loc;
- }
- return Loc;
-}
-
-/// \brief Warn about different locksets along backedges of loops.
-/// This function is called when we encounter a back edge. At that point,
-/// we need to verify that the lockset before taking the backedge is the
-/// same as the lockset before entering the loop.
-///
-/// \param LoopEntrySet Locks before starting the loop
-/// \param LoopReentrySet Locks in the last CFG block of the loop
-static void warnBackEdgeUnequalLocksets(ThreadSafetyHandler &Handler,
- const Lockset LoopReentrySet,
- const Lockset LoopEntrySet,
- SourceLocation FirstLocInLoop,
- Lockset::Factory &Fact) {
- assert(FirstLocInLoop.isValid());
- // Warn for locks held at the start of the loop, but not the end.
- for (Lockset::iterator I = LoopEntrySet.begin(), E = LoopEntrySet.end();
- I != E; ++I) {
- if (!LoopReentrySet.contains(I.getKey())) {
- // We report this error at the location of the first statement in a loop
- Handler.handleNoLockLoopEntry(I.getKey().getName(), FirstLocInLoop);
- }
- }
-
- // Warn for locks held at the end of the loop, but not at the start.
- warnIfNotInFirstSetOrNotSameKind(Handler, LoopEntrySet, LoopReentrySet,
- LoopReentrySet, Fact);
-}
-
-
-namespace clang { namespace thread_safety {
-/// \brief Check a function's CFG for thread-safety violations.
-///
-/// We traverse the blocks in the CFG, compute the set of mutexes that are held
-/// at the end of each block, and issue warnings for thread safety violations.
-/// Each block in the CFG is traversed exactly once.
-void runThreadSafetyAnalysis(AnalysisContext &AC,
- ThreadSafetyHandler &Handler) {
- CFG *CFGraph = AC.getCFG();
- if (!CFGraph) return;
- const Decl *D = AC.getDecl();
- if (D && D->getAttr<NoThreadSafetyAnalysisAttr>()) return;
-
- Lockset::Factory LocksetFactory;
-
- // FIXME: Swith to SmallVector? Otherwise improve performance impact?
- std::vector<Lockset> EntryLocksets(CFGraph->getNumBlockIDs(),
- LocksetFactory.getEmptyMap());
- std::vector<Lockset> ExitLocksets(CFGraph->getNumBlockIDs(),
- LocksetFactory.getEmptyMap());
-
- // We need to explore the CFG via a "topological" ordering.
- // That way, we will be guaranteed to have information about required
- // predecessor locksets when exploring a new block.
- TopologicallySortedCFG SortedGraph(CFGraph);
- CFGBlockSet VisitedBlocks(CFGraph);
-
- for (TopologicallySortedCFG::iterator I = SortedGraph.begin(),
- E = SortedGraph.end(); I!= E; ++I) {
- const CFGBlock *CurrBlock = *I;
- int CurrBlockID = CurrBlock->getBlockID();
-
- VisitedBlocks.insert(CurrBlock);
-
- // Use the default initial lockset in case there are no predecessors.
- Lockset &Entryset = EntryLocksets[CurrBlockID];
- Lockset &Exitset = ExitLocksets[CurrBlockID];
-
- // Iterate through the predecessor blocks and warn if the lockset for all
- // predecessors is not the same. We take the entry lockset of the current
- // block to be the intersection of all previous locksets.
- // FIXME: By keeping the intersection, we may output more errors in future
- // for a lock which is not in the intersection, but was in the union. We
- // may want to also keep the union in future. As an example, let's say
- // the intersection contains Mutex L, and the union contains L and M.
- // Later we unlock M. At this point, we would output an error because we
- // never locked M; although the real error is probably that we forgot to
- // lock M on all code paths. Conversely, let's say that later we lock M.
- // In this case, we should compare against the intersection instead of the
- // union because the real error is probably that we forgot to unlock M on
- // all code paths.
- bool LocksetInitialized = false;
- for (CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
- PE = CurrBlock->pred_end(); PI != PE; ++PI) {
-
- // if *PI -> CurrBlock is a back edge
- if (*PI == 0 || !VisitedBlocks.alreadySet(*PI))
- continue;
-
- int PrevBlockID = (*PI)->getBlockID();
- if (!LocksetInitialized) {
- Entryset = ExitLocksets[PrevBlockID];
- LocksetInitialized = true;
- } else {
- Entryset = intersectAndWarn(Handler, Entryset,
- ExitLocksets[PrevBlockID], LocksetFactory);
- }
- }
-
- BuildLockset LocksetBuilder(Handler, Entryset, LocksetFactory);
- for (CFGBlock::const_iterator BI = CurrBlock->begin(),
- BE = CurrBlock->end(); BI != BE; ++BI) {
- if (const CFGStmt *CfgStmt = dyn_cast<CFGStmt>(&*BI))
- LocksetBuilder.Visit(const_cast<Stmt*>(CfgStmt->getStmt()));
- }
- Exitset = LocksetBuilder.getLockset();
-
- // For every back edge from CurrBlock (the end of the loop) to another block
- // (FirstLoopBlock) we need to check that the Lockset of Block is equal to
- // the one held at the beginning of FirstLoopBlock. We can look up the
- // Lockset held at the beginning of FirstLoopBlock in the EntryLockSets map.
- for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
- SE = CurrBlock->succ_end(); SI != SE; ++SI) {
-
- // if CurrBlock -> *SI is *not* a back edge
- if (*SI == 0 || !VisitedBlocks.alreadySet(*SI))
- continue;
-
- CFGBlock *FirstLoopBlock = *SI;
- SourceLocation FirstLoopLocation = getFirstStmtLocation(FirstLoopBlock);
-
- assert(FirstLoopLocation.isValid());
-
- // Fail gracefully in release code.
- if (!FirstLoopLocation.isValid())
- continue;
-
- Lockset PreLoop = EntryLocksets[FirstLoopBlock->getBlockID()];
- Lockset LoopEnd = ExitLocksets[CurrBlockID];
- warnBackEdgeUnequalLocksets(Handler, LoopEnd, PreLoop, FirstLoopLocation,
- LocksetFactory);
- }
- }
-
- Lockset FinalLockset = ExitLocksets[CFGraph->getExit().getBlockID()];
- if (!FinalLockset.isEmpty()) {
- for (Lockset::iterator I=FinalLockset.begin(), E=FinalLockset.end();
- I != E; ++I) {
- const MutexID &Mutex = I.getKey();
- const LockData &MissingLock = I.getData();
-
- std::string FunName = "<unknown>";
- if (const NamedDecl *ContextDecl = dyn_cast<NamedDecl>(AC.getDecl())) {
- FunName = ContextDecl->getDeclName().getAsString();
- }
-
- Handler.handleNoUnlock(Mutex.getName(), FunName, MissingLock.AcquireLoc);
- }
- }
-}
-
-}} // end namespace clang::thread_safety
-
-
//===----------------------------------------------------------------------===//
// AnalysisBasedWarnings - Worker object used by Sema to execute analysis-based
// warnings on a function, method, or block.
projects / clang / commitdiff