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Diffstat (limited to 'contrib/llvm-project/clang/include/clang/Analysis/Analyses/ThreadSafety.h')
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1 files changed, 252 insertions, 0 deletions
diff --git a/contrib/llvm-project/clang/include/clang/Analysis/Analyses/ThreadSafety.h b/contrib/llvm-project/clang/include/clang/Analysis/Analyses/ThreadSafety.h new file mode 100644 index 000000000000..18659aa4e5bb --- /dev/null +++ b/contrib/llvm-project/clang/include/clang/Analysis/Analyses/ThreadSafety.h @@ -0,0 +1,252 @@ +//===- ThreadSafety.h -------------------------------------------*- C++ -*-===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// +// A intra-procedural analysis for thread safety (e.g. deadlocks and race +// conditions), based off of an annotation system. +// +// See http://clang.llvm.org/docs/LanguageExtensions.html#thread-safety-annotation-checking +// for more information. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_CLANG_ANALYSIS_ANALYSES_THREADSAFETY_H +#define LLVM_CLANG_ANALYSIS_ANALYSES_THREADSAFETY_H + +#include "clang/Basic/SourceLocation.h" +#include "llvm/ADT/StringRef.h" + +namespace clang { + +class AnalysisDeclContext; +class FunctionDecl; +class NamedDecl; + +namespace threadSafety { + +class BeforeSet; + +/// This enum distinguishes between different kinds of operations that may +/// need to be protected by locks. We use this enum in error handling. +enum ProtectedOperationKind { + /// Dereferencing a variable (e.g. p in *p = 5;) + POK_VarDereference, + + /// Reading or writing a variable (e.g. x in x = 5;) + POK_VarAccess, + + /// Making a function call (e.g. fool()) + POK_FunctionCall, + + /// Passing a guarded variable by reference. + POK_PassByRef, + + /// Passing a pt-guarded variable by reference. + POK_PtPassByRef +}; + +/// This enum distinguishes between different kinds of lock actions. For +/// example, it is an error to write a variable protected by shared version of a +/// mutex. +enum LockKind { + /// Shared/reader lock of a mutex. + LK_Shared, + + /// Exclusive/writer lock of a mutex. + LK_Exclusive, + + /// Can be either Shared or Exclusive. + LK_Generic +}; + +/// This enum distinguishes between different ways to access (read or write) a +/// variable. +enum AccessKind { + /// Reading a variable. + AK_Read, + + /// Writing a variable. + AK_Written +}; + +/// This enum distinguishes between different situations where we warn due to +/// inconsistent locking. +/// \enum SK_LockedSomeLoopIterations -- a mutex is locked for some but not all +/// loop iterations. +/// \enum SK_LockedSomePredecessors -- a mutex is locked in some but not all +/// predecessors of a CFGBlock. +/// \enum SK_LockedAtEndOfFunction -- a mutex is still locked at the end of a +/// function. +enum LockErrorKind { + LEK_LockedSomeLoopIterations, + LEK_LockedSomePredecessors, + LEK_LockedAtEndOfFunction, + LEK_NotLockedAtEndOfFunction +}; + +/// Handler class for thread safety warnings. +class ThreadSafetyHandler { +public: + using Name = StringRef; + + ThreadSafetyHandler() = default; + virtual ~ThreadSafetyHandler(); + + /// Warn about lock expressions which fail to resolve to lockable objects. + /// \param Kind -- the capability's name parameter (role, mutex, etc). + /// \param Loc -- the SourceLocation of the unresolved expression. + virtual void handleInvalidLockExp(StringRef Kind, SourceLocation Loc) {} + + /// Warn about unlock function calls that do not have a prior matching lock + /// expression. + /// \param Kind -- the capability's name parameter (role, mutex, etc). + /// \param LockName -- A StringRef name for the lock expression, to be printed + /// in the error message. + /// \param Loc -- The SourceLocation of the Unlock + virtual void handleUnmatchedUnlock(StringRef Kind, Name LockName, + SourceLocation Loc) {} + + /// Warn about an unlock function call that attempts to unlock a lock with + /// the incorrect lock kind. For instance, a shared lock being unlocked + /// exclusively, or vice versa. + /// \param LockName -- A StringRef name for the lock expression, to be printed + /// in the error message. + /// \param Kind -- the capability's name parameter (role, mutex, etc). + /// \param Expected -- the kind of lock expected. + /// \param Received -- the kind of lock received. + /// \param LocLocked -- The SourceLocation of the Lock. + /// \param LocUnlock -- The SourceLocation of the Unlock. + virtual void handleIncorrectUnlockKind(StringRef Kind, Name LockName, + LockKind Expected, LockKind Received, + SourceLocation LocLocked, + SourceLocation LocUnlock) {} + + /// Warn about lock function calls for locks which are already held. + /// \param Kind -- the capability's name parameter (role, mutex, etc). + /// \param LockName -- A StringRef name for the lock expression, to be printed + /// in the error message. + /// \param LocLocked -- The location of the first lock expression. + /// \param LocDoubleLock -- The location of the second lock expression. + virtual void handleDoubleLock(StringRef Kind, Name LockName, + SourceLocation LocLocked, + SourceLocation LocDoubleLock) {} + + /// Warn about situations where a mutex is sometimes held and sometimes not. + /// The three situations are: + /// 1. a mutex is locked on an "if" branch but not the "else" branch, + /// 2, or a mutex is only held at the start of some loop iterations, + /// 3. or when a mutex is locked but not unlocked inside a function. + /// \param Kind -- the capability's name parameter (role, mutex, etc). + /// \param LockName -- A StringRef name for the lock expression, to be printed + /// in the error message. + /// \param LocLocked -- The location of the lock expression where the mutex is + /// locked + /// \param LocEndOfScope -- The location of the end of the scope where the + /// mutex is no longer held + /// \param LEK -- which of the three above cases we should warn for + virtual void handleMutexHeldEndOfScope(StringRef Kind, Name LockName, + SourceLocation LocLocked, + SourceLocation LocEndOfScope, + LockErrorKind LEK) {} + + /// Warn when a mutex is held exclusively and shared at the same point. For + /// example, if a mutex is locked exclusively during an if branch and shared + /// during the else branch. + /// \param Kind -- the capability's name parameter (role, mutex, etc). + /// \param LockName -- A StringRef name for the lock expression, to be printed + /// in the error message. + /// \param Loc1 -- The location of the first lock expression. + /// \param Loc2 -- The location of the second lock expression. + virtual void handleExclusiveAndShared(StringRef Kind, Name LockName, + SourceLocation Loc1, + SourceLocation Loc2) {} + + /// Warn when a protected operation occurs while no locks are held. + /// \param Kind -- the capability's name parameter (role, mutex, etc). + /// \param D -- The decl for the protected variable or function + /// \param POK -- The kind of protected operation (e.g. variable access) + /// \param AK -- The kind of access (i.e. read or write) that occurred + /// \param Loc -- The location of the protected operation. + virtual void handleNoMutexHeld(StringRef Kind, const NamedDecl *D, + ProtectedOperationKind POK, AccessKind AK, + SourceLocation Loc) {} + + /// Warn when a protected operation occurs while the specific mutex protecting + /// the operation is not locked. + /// \param Kind -- the capability's name parameter (role, mutex, etc). + /// \param D -- The decl for the protected variable or function + /// \param POK -- The kind of protected operation (e.g. variable access) + /// \param LockName -- A StringRef name for the lock expression, to be printed + /// in the error message. + /// \param LK -- The kind of access (i.e. read or write) that occurred + /// \param Loc -- The location of the protected operation. + virtual void handleMutexNotHeld(StringRef Kind, const NamedDecl *D, + ProtectedOperationKind POK, Name LockName, + LockKind LK, SourceLocation Loc, + Name *PossibleMatch = nullptr) {} + + /// Warn when acquiring a lock that the negative capability is not held. + /// \param Kind -- the capability's name parameter (role, mutex, etc). + /// \param LockName -- The name for the lock expression, to be printed in the + /// diagnostic. + /// \param Neg -- The name of the negative capability to be printed in the + /// diagnostic. + /// \param Loc -- The location of the protected operation. + virtual void handleNegativeNotHeld(StringRef Kind, Name LockName, Name Neg, + SourceLocation Loc) {} + + /// Warn when a function is called while an excluded mutex is locked. For + /// example, the mutex may be locked inside the function. + /// \param Kind -- the capability's name parameter (role, mutex, etc). + /// \param FunName -- The name of the function + /// \param LockName -- A StringRef name for the lock expression, to be printed + /// in the error message. + /// \param Loc -- The location of the function call. + virtual void handleFunExcludesLock(StringRef Kind, Name FunName, + Name LockName, SourceLocation Loc) {} + + /// Warn that L1 cannot be acquired before L2. + virtual void handleLockAcquiredBefore(StringRef Kind, Name L1Name, + Name L2Name, SourceLocation Loc) {} + + /// Warn that there is a cycle in acquired_before/after dependencies. + virtual void handleBeforeAfterCycle(Name L1Name, SourceLocation Loc) {} + + /// Called by the analysis when starting analysis of a function. + /// Used to issue suggestions for changes to annotations. + virtual void enterFunction(const FunctionDecl *FD) {} + + /// Called by the analysis when finishing analysis of a function. + virtual void leaveFunction(const FunctionDecl *FD) {} + + bool issueBetaWarnings() { return IssueBetaWarnings; } + void setIssueBetaWarnings(bool b) { IssueBetaWarnings = b; } + +private: + bool IssueBetaWarnings = false; +}; + +/// Check a function's CFG for thread-safety violations. +/// +/// We traverse the blocks in the CFG, compute the set of mutexes that are held +/// at the end of each block, and issue warnings for thread safety violations. +/// Each block in the CFG is traversed exactly once. +void runThreadSafetyAnalysis(AnalysisDeclContext &AC, + ThreadSafetyHandler &Handler, + BeforeSet **Bset); + +void threadSafetyCleanup(BeforeSet *Cache); + +/// Helper function that returns a LockKind required for the given level +/// of access. +LockKind getLockKindFromAccessKind(AccessKind AK); + +} // namespace threadSafety +} // namespace clang + +#endif // LLVM_CLANG_ANALYSIS_ANALYSES_THREADSAFETY_H |