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/AnalysisContext.h"
23#include "clang/Basic/SourceLocation.h"
24#include "llvm/ADT/StringRef.h"
25
26namespace clang {
27namespace threadSafety {
28
29class 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.
33enum 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.
44enum 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.
52enum 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.
65enum LockErrorKind {
66  LEK_LockedSomeLoopIterations,
67  LEK_LockedSomePredecessors,
68  LEK_LockedAtEndOfFunction,
69  LEK_NotLockedAtEndOfFunction
70};
71
72/// Handler class for thread safety warnings.
73class ThreadSafetyHandler {
74public:
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
206private:
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.
215void runThreadSafetyAnalysis(AnalysisDeclContext &AC,
216                             ThreadSafetyHandler &Handler,
217                             BeforeSet **Bset);
218
219void threadSafetyCleanup(BeforeSet *Cache);
220
221/// \brief Helper function that returns a LockKind required for the given level
222/// of access.
223LockKind getLockKindFromAccessKind(AccessKind AK);
224
225}} // end namespace clang::threadSafety
226#endif
227