1 //===- ThreadSafety.h ------------------------------------------*- 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 //===----------------------------------------------------------------------===//
11 // A intra-procedural analysis for thread safety (e.g. deadlocks and race
12 // conditions), based off of an annotation system.
14 // See http://clang.llvm.org/docs/LanguageExtensions.html#threadsafety for more
17 //===----------------------------------------------------------------------===//
19 #ifndef LLVM_CLANG_THREADSAFETY_H
20 #define LLVM_CLANG_THREADSAFETY_H
22 #include "clang/Analysis/AnalysisContext.h"
23 #include "clang/Basic/SourceLocation.h"
24 #include "llvm/ADT/StringRef.h"
27 namespace thread_safety {
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.
31 enum 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())
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
41 LK_Shared, /// Shared/reader lock of a mutex
42 LK_Exclusive /// Exclusive/writer lock of a mutex
45 /// This enum distinguishes between different ways to access (read or write) a
48 AK_Read, /// Reading a variable
49 AK_Written /// Writing a variable
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
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
61 LEK_LockedSomeLoopIterations,
62 LEK_LockedSomePredecessors,
63 LEK_LockedAtEndOfFunction
66 /// Handler class for thread safety warnings.
67 class ThreadSafetyHandler {
69 typedef llvm::StringRef Name;
70 virtual ~ThreadSafetyHandler() = 0;
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) {}
76 /// Warn about unlock function calls that do not have a prior matching lock
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) {}
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) {}
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,
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) {}
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) {}
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) {}
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) {}
141 /// \brief Check a function's CFG for thread-safety violations.
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.
146 void runThreadSafetyAnalysis(AnalysisContext &AC, ThreadSafetyHandler &Handler);
148 /// \brief Helper function that returns a LockKind required for the given level
150 LockKind getLockKindFromAccessKind(AccessKind AK);
152 }} // end namespace clang::thread_safety