1 //===- ThreadSafety.h ------------------------------------------*- C++ --*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // 11 // A intra-procedural analysis for thread safety (e.g. deadlocks and race 12 // conditions), based off of an annotation system. 13 // 14 // See http://clang.llvm.org/docs/LanguageExtensions.html#thread-safety-annotation-checking 15 // for more information. 16 // 17 //===----------------------------------------------------------------------===// 18 19 #ifndef LLVM_CLANG_ANALYSIS_ANALYSES_THREADSAFETY_H 20 #define LLVM_CLANG_ANALYSIS_ANALYSES_THREADSAFETY_H 21 22 #include "clang/Analysis/AnalysisDeclContext.h" 23 #include "clang/Basic/SourceLocation.h" 24 #include "llvm/ADT/StringRef.h" 25 26 namespace clang { 27 namespace threadSafety { 28 29 class BeforeSet; 30 31 /// This enum distinguishes between different kinds of operations that may 32 /// need to be protected by locks. We use this enum in error handling. 33 enum ProtectedOperationKind { 34 POK_VarDereference, ///< Dereferencing a variable (e.g. p in *p = 5;) 35 POK_VarAccess, ///< Reading or writing a variable (e.g. x in x = 5;) 36 POK_FunctionCall, ///< Making a function call (e.g. fool()) 37 POK_PassByRef, ///< Passing a guarded variable by reference. 38 POK_PtPassByRef, ///< Passing a pt-guarded variable by reference. 39 }; 40 41 /// This enum distinguishes between different kinds of lock actions. For 42 /// example, it is an error to write a variable protected by shared version of a 43 /// mutex. 44 enum LockKind { 45 LK_Shared, ///< Shared/reader lock of a mutex. 46 LK_Exclusive, ///< Exclusive/writer lock of a mutex. 47 LK_Generic ///< Can be either Shared or Exclusive 48 }; 49 50 /// This enum distinguishes between different ways to access (read or write) a 51 /// variable. 52 enum AccessKind { 53 AK_Read, ///< Reading a variable. 54 AK_Written ///< Writing a variable. 55 }; 56 57 /// This enum distinguishes between different situations where we warn due to 58 /// inconsistent locking. 59 /// \enum SK_LockedSomeLoopIterations -- a mutex is locked for some but not all 60 /// loop iterations. 61 /// \enum SK_LockedSomePredecessors -- a mutex is locked in some but not all 62 /// predecessors of a CFGBlock. 63 /// \enum SK_LockedAtEndOfFunction -- a mutex is still locked at the end of a 64 /// function. 65 enum LockErrorKind { 66 LEK_LockedSomeLoopIterations, 67 LEK_LockedSomePredecessors, 68 LEK_LockedAtEndOfFunction, 69 LEK_NotLockedAtEndOfFunction 70 }; 71 72 /// Handler class for thread safety warnings. 73 class ThreadSafetyHandler { 74 public: 75 typedef StringRef Name; 76 ThreadSafetyHandler() : IssueBetaWarnings(false) { } 77 virtual ~ThreadSafetyHandler(); 78 79 /// Warn about lock expressions which fail to resolve to lockable objects. 80 /// \param Kind -- the capability's name parameter (role, mutex, etc). 81 /// \param Loc -- the SourceLocation of the unresolved expression. 82 virtual void handleInvalidLockExp(StringRef Kind, SourceLocation Loc) {} 83 84 /// Warn about unlock function calls that do not have a prior matching lock 85 /// expression. 86 /// \param Kind -- the capability's name parameter (role, mutex, etc). 87 /// \param LockName -- A StringRef name for the lock expression, to be printed 88 /// in the error message. 89 /// \param Loc -- The SourceLocation of the Unlock 90 virtual void handleUnmatchedUnlock(StringRef Kind, Name LockName, 91 SourceLocation Loc) {} 92 93 /// Warn about an unlock function call that attempts to unlock a lock with 94 /// the incorrect lock kind. For instance, a shared lock being unlocked 95 /// exclusively, or vice versa. 96 /// \param LockName -- A StringRef name for the lock expression, to be printed 97 /// in the error message. 98 /// \param Kind -- the capability's name parameter (role, mutex, etc). 99 /// \param Expected -- the kind of lock expected. 100 /// \param Received -- the kind of lock received. 101 /// \param Loc -- The SourceLocation of the Unlock. 102 virtual void handleIncorrectUnlockKind(StringRef Kind, Name LockName, 103 LockKind Expected, LockKind Received, 104 SourceLocation Loc) {} 105 106 /// Warn about lock function calls for locks which are already held. 107 /// \param Kind -- the capability's name parameter (role, mutex, etc). 108 /// \param LockName -- A StringRef name for the lock expression, to be printed 109 /// in the error message. 110 /// \param Loc -- The location of the second lock expression. 111 virtual void handleDoubleLock(StringRef Kind, Name LockName, 112 SourceLocation Loc) {} 113 114 /// Warn about situations where a mutex is sometimes held and sometimes not. 115 /// The three situations are: 116 /// 1. a mutex is locked on an "if" branch but not the "else" branch, 117 /// 2, or a mutex is only held at the start of some loop iterations, 118 /// 3. or when a mutex is locked but not unlocked inside a function. 119 /// \param Kind -- the capability's name parameter (role, mutex, etc). 120 /// \param LockName -- A StringRef name for the lock expression, to be printed 121 /// in the error message. 122 /// \param LocLocked -- The location of the lock expression where the mutex is 123 /// locked 124 /// \param LocEndOfScope -- The location of the end of the scope where the 125 /// mutex is no longer held 126 /// \param LEK -- which of the three above cases we should warn for 127 virtual void handleMutexHeldEndOfScope(StringRef Kind, Name LockName, 128 SourceLocation LocLocked, 129 SourceLocation LocEndOfScope, 130 LockErrorKind LEK) {} 131 132 /// Warn when a mutex is held exclusively and shared at the same point. For 133 /// example, if a mutex is locked exclusively during an if branch and shared 134 /// during the else branch. 135 /// \param Kind -- the capability's name parameter (role, mutex, etc). 136 /// \param LockName -- A StringRef name for the lock expression, to be printed 137 /// in the error message. 138 /// \param Loc1 -- The location of the first lock expression. 139 /// \param Loc2 -- The location of the second lock expression. 140 virtual void handleExclusiveAndShared(StringRef Kind, Name LockName, 141 SourceLocation Loc1, 142 SourceLocation Loc2) {} 143 144 /// Warn when a protected operation occurs while no locks are held. 145 /// \param Kind -- the capability's name parameter (role, mutex, etc). 146 /// \param D -- The decl for the protected variable or function 147 /// \param POK -- The kind of protected operation (e.g. variable access) 148 /// \param AK -- The kind of access (i.e. read or write) that occurred 149 /// \param Loc -- The location of the protected operation. 150 virtual void handleNoMutexHeld(StringRef Kind, const NamedDecl *D, 151 ProtectedOperationKind POK, AccessKind AK, 152 SourceLocation Loc) {} 153 154 /// Warn when a protected operation occurs while the specific mutex protecting 155 /// the operation is not locked. 156 /// \param Kind -- the capability's name parameter (role, mutex, etc). 157 /// \param D -- The decl for the protected variable or function 158 /// \param POK -- The kind of protected operation (e.g. variable access) 159 /// \param LockName -- A StringRef name for the lock expression, to be printed 160 /// in the error message. 161 /// \param LK -- The kind of access (i.e. read or write) that occurred 162 /// \param Loc -- The location of the protected operation. 163 virtual void handleMutexNotHeld(StringRef Kind, const NamedDecl *D, 164 ProtectedOperationKind POK, Name LockName, 165 LockKind LK, SourceLocation Loc, 166 Name *PossibleMatch = nullptr) {} 167 168 /// Warn when acquiring a lock that the negative capability is not held. 169 /// \param Kind -- the capability's name parameter (role, mutex, etc). 170 /// \param LockName -- The name for the lock expression, to be printed in the 171 /// diagnostic. 172 /// \param Neg -- The name of the negative capability to be printed in the 173 /// diagnostic. 174 /// \param Loc -- The location of the protected operation. 175 virtual void handleNegativeNotHeld(StringRef Kind, Name LockName, Name Neg, 176 SourceLocation Loc) {} 177 178 /// Warn when a function is called while an excluded mutex is locked. For 179 /// example, the mutex may be locked inside the function. 180 /// \param Kind -- the capability's name parameter (role, mutex, etc). 181 /// \param FunName -- The name of the function 182 /// \param LockName -- A StringRef name for the lock expression, to be printed 183 /// in the error message. 184 /// \param Loc -- The location of the function call. 185 virtual void handleFunExcludesLock(StringRef Kind, Name FunName, 186 Name LockName, SourceLocation Loc) {} 187 188 189 /// Warn that L1 cannot be acquired before L2. 190 virtual void handleLockAcquiredBefore(StringRef Kind, Name L1Name, 191 Name L2Name, SourceLocation Loc) {} 192 193 /// Warn that there is a cycle in acquired_before/after dependencies. 194 virtual void handleBeforeAfterCycle(Name L1Name, SourceLocation Loc) {} 195 196 /// Called by the analysis when starting analysis of a function. 197 /// Used to issue suggestions for changes to annotations. 198 virtual void enterFunction(const FunctionDecl *FD) {} 199 200 /// Called by the analysis when finishing analysis of a function. 201 virtual void leaveFunction(const FunctionDecl *FD) {} 202 203 bool issueBetaWarnings() { return IssueBetaWarnings; } 204 void setIssueBetaWarnings(bool b) { IssueBetaWarnings = b; } 205 206 private: 207 bool IssueBetaWarnings; 208 }; 209 210 /// \brief Check a function's CFG for thread-safety violations. 211 /// 212 /// We traverse the blocks in the CFG, compute the set of mutexes that are held 213 /// at the end of each block, and issue warnings for thread safety violations. 214 /// Each block in the CFG is traversed exactly once. 215 void runThreadSafetyAnalysis(AnalysisDeclContext &AC, 216 ThreadSafetyHandler &Handler, 217 BeforeSet **Bset); 218 219 void threadSafetyCleanup(BeforeSet *Cache); 220 221 /// \brief Helper function that returns a LockKind required for the given level 222 /// of access. 223 LockKind getLockKindFromAccessKind(AccessKind AK); 224 225 }} // end namespace clang::threadSafety 226 #endif 227
