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,
64 LEK_NotLockedAtEndOfFunction
67 /// Handler class for thread safety warnings.
68 class ThreadSafetyHandler {
70 typedef llvm::StringRef Name;
71 virtual ~ThreadSafetyHandler();
73 /// Warn about lock expressions which fail to resolve to lockable objects.
74 /// \param Loc -- the SourceLocation of the unresolved expression.
75 virtual void handleInvalidLockExp(SourceLocation Loc) {}
77 /// Warn about unlock function calls that do not have a prior matching lock
79 /// \param LockName -- A StringRef name for the lock expression, to be printed
80 /// in the error message.
81 /// \param Loc -- The SourceLocation of the Unlock
82 virtual void handleUnmatchedUnlock(Name LockName, SourceLocation Loc) {}
84 /// Warn about lock function calls for locks which are already held.
85 /// \param LockName -- A StringRef name for the lock expression, to be printed
86 /// in the error message.
87 /// \param Loc -- The location of the second lock expression.
88 virtual void handleDoubleLock(Name LockName, SourceLocation Loc) {}
90 /// Warn about situations where a mutex is sometimes held and sometimes not.
91 /// The three situations are:
92 /// 1. a mutex is locked on an "if" branch but not the "else" branch,
93 /// 2, or a mutex is only held at the start of some loop iterations,
94 /// 3. or when a mutex is locked but not unlocked inside a function.
95 /// \param LockName -- A StringRef name for the lock expression, to be printed
96 /// in the error message.
97 /// \param LocLocked -- The location of the lock expression where the mutex is
99 /// \param LocEndOfScope -- The location of the end of the scope where the
100 /// mutex is no longer held
101 /// \param LEK -- which of the three above cases we should warn for
102 virtual void handleMutexHeldEndOfScope(Name LockName,
103 SourceLocation LocLocked,
104 SourceLocation LocEndOfScope,
107 /// Warn when a mutex is held exclusively and shared at the same point. For
108 /// example, if a mutex is locked exclusively during an if branch and shared
109 /// during the else branch.
110 /// \param LockName -- A StringRef name for the lock expression, to be printed
111 /// in the error message.
112 /// \param Loc1 -- The location of the first lock expression.
113 /// \param Loc2 -- The location of the second lock expression.
114 virtual void handleExclusiveAndShared(Name LockName, SourceLocation Loc1,
115 SourceLocation Loc2) {}
117 /// Warn when a protected operation occurs while no locks are held.
118 /// \param D -- The decl for the protected variable or function
119 /// \param POK -- The kind of protected operation (e.g. variable access)
120 /// \param AK -- The kind of access (i.e. read or write) that occurred
121 /// \param Loc -- The location of the protected operation.
122 virtual void handleNoMutexHeld(const NamedDecl *D, ProtectedOperationKind POK,
123 AccessKind AK, SourceLocation Loc) {}
125 /// Warn when a protected operation occurs while the specific mutex protecting
126 /// the operation is not locked.
127 /// \param D -- The decl for the protected variable or function
128 /// \param POK -- The kind of protected operation (e.g. variable access)
129 /// \param LockName -- A StringRef name for the lock expression, to be printed
130 /// in the error message.
131 /// \param LK -- The kind of access (i.e. read or write) that occurred
132 /// \param Loc -- The location of the protected operation.
133 virtual void handleMutexNotHeld(const NamedDecl *D,
134 ProtectedOperationKind POK, Name LockName,
135 LockKind LK, SourceLocation Loc,
136 Name *PossibleMatch=0) {}
138 /// Warn when a function is called while an excluded mutex is locked. For
139 /// example, the mutex may be locked inside the function.
140 /// \param FunName -- The name of the function
141 /// \param LockName -- A StringRef name for the lock expression, to be printed
142 /// in the error message.
143 /// \param Loc -- The location of the function call.
144 virtual void handleFunExcludesLock(Name FunName, Name LockName,
145 SourceLocation Loc) {}
148 /// \brief Check a function's CFG for thread-safety violations.
150 /// We traverse the blocks in the CFG, compute the set of mutexes that are held
151 /// at the end of each block, and issue warnings for thread safety violations.
152 /// Each block in the CFG is traversed exactly once.
153 void runThreadSafetyAnalysis(AnalysisDeclContext &AC,
154 ThreadSafetyHandler &Handler);
156 /// \brief Helper function that returns a LockKind required for the given level
158 LockKind getLockKindFromAccessKind(AccessKind AK);
160 }} // end namespace clang::thread_safety