ThreadSafety.h revision 9f80a97408ee0da939654d851ff42ad07d47e9c7
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#threadsafety for more 15// information. 16// 17//===----------------------------------------------------------------------===// 18 19#ifndef LLVM_CLANG_THREADSAFETY_H 20#define LLVM_CLANG_THREADSAFETY_H 21 22#include "clang/Analysis/AnalysisContext.h" 23#include "clang/Basic/SourceLocation.h" 24#include "llvm/ADT/StringRef.h" 25 26namespace clang { 27namespace thread_safety { 28 29/// This enum distinguishes between different kinds of operations that may 30/// need to be protected by locks. We use this enum in error handling. 31enum ProtectedOperationKind { 32 POK_VarDereference, /// Dereferencing a variable (e.g. p in *p = 5;) 33 POK_VarAccess, /// Reading or writing a variable (e.g. x in x = 5;) 34 POK_FunctionCall /// Making a function call (e.g. fool()) 35}; 36 37/// This enum distinguishes between different kinds of lock actions. For 38/// example, it is an error to write a variable protected by shared version of a 39/// mutex. 40enum LockKind { 41 LK_Shared, /// Shared/reader lock of a mutex 42 LK_Exclusive /// Exclusive/writer lock of a mutex 43}; 44 45/// This enum distinguishes between different ways to access (read or write) a 46/// variable. 47enum AccessKind { 48 AK_Read, /// Reading a variable 49 AK_Written /// Writing a variable 50}; 51 52/// This enum distinguishes between different situations where we warn due to 53/// inconsistent locking. 54/// \enum SK_LockedSomeLoopIterations -- a mutex is locked for some but not all 55/// loop iterations. 56/// \enum SK_LockedSomePredecessors -- a mutex is locked in some but not all 57/// predecessors of a CFGBlock. 58/// \enum SK_LockedAtEndOfFunction -- a mutex is still locked at the end of a 59/// function. 60enum LockErrorKind { 61 LEK_LockedSomeLoopIterations, 62 LEK_LockedSomePredecessors, 63 LEK_LockedAtEndOfFunction 64}; 65 66/// Handler class for thread safety warnings. 67class ThreadSafetyHandler { 68public: 69 typedef llvm::StringRef Name; 70 virtual ~ThreadSafetyHandler(); 71 72 /// Warn about lock expressions which fail to resolve to lockable objects. 73 /// \param Loc -- the SourceLocation of the unresolved expression. 74 virtual void handleInvalidLockExp(SourceLocation Loc) {} 75 76 /// Warn about unlock function calls that do not have a prior matching lock 77 /// expression. 78 /// \param LockName -- A StringRef name for the lock expression, to be printed 79 /// in the error message. 80 /// \param Loc -- The SourceLocation of the Unlock 81 virtual void handleUnmatchedUnlock(Name LockName, SourceLocation Loc) {} 82 83 /// Warn about lock function calls for locks which are already held. 84 /// \param LockName -- A StringRef name for the lock expression, to be printed 85 /// in the error message. 86 /// \param Loc -- The location of the second lock expression. 87 virtual void handleDoubleLock(Name LockName, SourceLocation Loc) {} 88 89 /// Warn about situations where a mutex is sometimes held and sometimes not. 90 /// The three situations are: 91 /// 1. a mutex is locked on an "if" branch but not the "else" branch, 92 /// 2, or a mutex is only held at the start of some loop iterations, 93 /// 3. or when a mutex is locked but not unlocked inside a function. 94 /// \param LockName -- A StringRef name for the lock expression, to be printed 95 /// in the error message. 96 /// \param Loc -- The location of the lock expression where the mutex is locked 97 /// \param LEK -- which of the three above cases we should warn for 98 virtual void handleMutexHeldEndOfScope(Name LockName, SourceLocation Loc, 99 LockErrorKind LEK){} 100 101 /// Warn when a mutex is held exclusively and shared at the same point. For 102 /// example, if a mutex is locked exclusively during an if branch and shared 103 /// during the else branch. 104 /// \param LockName -- A StringRef name for the lock expression, to be printed 105 /// in the error message. 106 /// \param Loc1 -- The location of the first lock expression. 107 /// \param Loc2 -- The location of the second lock expression. 108 virtual void handleExclusiveAndShared(Name LockName, SourceLocation Loc1, 109 SourceLocation Loc2) {} 110 111 /// Warn when a protected operation occurs while no locks are held. 112 /// \param D -- The decl for the protected variable or function 113 /// \param POK -- The kind of protected operation (e.g. variable access) 114 /// \param AK -- The kind of access (i.e. read or write) that occurred 115 /// \param Loc -- The location of the protected operation. 116 virtual void handleNoMutexHeld(const NamedDecl *D, ProtectedOperationKind POK, 117 AccessKind AK, SourceLocation Loc) {} 118 119 /// Warn when a protected operation occurs while the specific mutex protecting 120 /// the operation is not locked. 121 /// \param LockName -- A StringRef name for the lock expression, to be printed 122 /// in the error message. 123 /// \param D -- The decl for the protected variable or function 124 /// \param POK -- The kind of protected operation (e.g. variable access) 125 /// \param AK -- The kind of access (i.e. read or write) that occurred 126 /// \param Loc -- The location of the protected operation. 127 virtual void handleMutexNotHeld(const NamedDecl *D, 128 ProtectedOperationKind POK, Name LockName, 129 LockKind LK, SourceLocation Loc) {} 130 131 /// Warn when a function is called while an excluded mutex is locked. For 132 /// example, the mutex may be locked inside the function. 133 /// \param FunName -- The name of the function 134 /// \param LockName -- A StringRef name for the lock expression, to be printed 135 /// in the error message. 136 /// \param Loc -- The location of the function call. 137 virtual void handleFunExcludesLock(Name FunName, Name LockName, 138 SourceLocation Loc) {} 139}; 140 141/// \brief Check a function's CFG for thread-safety violations. 142/// 143/// We traverse the blocks in the CFG, compute the set of mutexes that are held 144/// at the end of each block, and issue warnings for thread safety violations. 145/// Each block in the CFG is traversed exactly once. 146void runThreadSafetyAnalysis(AnalysisContext &AC, ThreadSafetyHandler &Handler); 147 148/// \brief Helper function that returns a LockKind required for the given level 149/// of access. 150LockKind getLockKindFromAccessKind(AccessKind AK); 151 152}} // end namespace clang::thread_safety 153#endif 154