aaronpuchert created this revision.
aaronpuchert added reviewers: aaron.ballman, delesley.
Herald added a subscriber: cfe-commits.
The pattern is problematic with C++ exceptions, and not as widespread as
scoped locks, but it's still used by some, for example Chromium.
We are a bit stricter here at join points, patterns that are allowed for
scoped locks aren't allowed here. That could still be changed in the
future, but I'd argue we should only relax this if people ask for it.
Fixes PR36162.
Repository:
rC Clang
https://reviews.llvm.org/D52578
Files:
lib/Analysis/ThreadSafety.cpp
test/SemaCXX/warn-thread-safety-analysis.cpp
Index: test/SemaCXX/warn-thread-safety-analysis.cpp
===================================================================
--- test/SemaCXX/warn-thread-safety-analysis.cpp
+++ test/SemaCXX/warn-thread-safety-analysis.cpp
@@ -2755,6 +2755,85 @@
} // end namespace RelockableScopedLock
+namespace ScopedUnlock {
+
+class SCOPED_LOCKABLE MutexUnlock {
+public:
+ MutexUnlock(Mutex *mu) EXCLUSIVE_UNLOCK_FUNCTION(mu);
+ ~MutexUnlock() EXCLUSIVE_UNLOCK_FUNCTION();
+
+ void Lock() EXCLUSIVE_UNLOCK_FUNCTION();
+ void Unlock() EXCLUSIVE_LOCK_FUNCTION();
+};
+
+Mutex mu;
+int x GUARDED_BY(mu);
+bool c;
+
+void simple() EXCLUSIVE_LOCKS_REQUIRED(mu) {
+ x = 1;
+ MutexUnlock scope(&mu);
+ x = 2; // expected-warning {{writing variable 'x' requires holding mutex 'mu' exclusively}}
+}
+
+void innerUnlock() {
+ MutexLock outer(&mu);
+ if (x == 0) {
+ MutexUnlock inner(&mu);
+ x = 1; // expected-warning {{writing variable 'x' requires holding mutex 'mu' exclusively}}
+ }
+ x = 2;
+}
+
+void manual() EXCLUSIVE_LOCKS_REQUIRED(mu) {
+ MutexUnlock scope(&mu);
+ scope.Lock();
+ x = 2;
+ scope.Unlock();
+ x = 3; // expected-warning {{writing variable 'x' requires holding mutex 'mu' exclusively}}
+}
+
+void join() EXCLUSIVE_LOCKS_REQUIRED(mu) {
+ MutexUnlock scope(&mu);
+ if (c) {
+ scope.Lock(); // expected-note{{mutex acquired here}}
+ }
+ // expected-warning@+1{{mutex 'mu' is not held on every path through here}}
+ scope.Lock();
+}
+
+void doubleLock() EXCLUSIVE_LOCKS_REQUIRED(mu) {
+ MutexUnlock scope(&mu);
+ scope.Lock();
+ scope.Lock(); // expected-warning {{acquiring mutex 'mu' that is already held}}
+}
+
+void doubleUnlock() EXCLUSIVE_LOCKS_REQUIRED(mu) {
+ MutexUnlock scope(&mu);
+ scope.Unlock(); // expected-warning {{releasing mutex 'mu' that was not held}}
+}
+
+class SCOPED_LOCKABLE MutexLockUnlock {
+public:
+ MutexLockUnlock(Mutex *mu1, Mutex *mu2) EXCLUSIVE_UNLOCK_FUNCTION(mu1) EXCLUSIVE_LOCK_FUNCTION(mu2);
+ ~MutexLockUnlock() EXCLUSIVE_UNLOCK_FUNCTION();
+
+ void Release() EXCLUSIVE_UNLOCK_FUNCTION();
+ void Acquire() EXCLUSIVE_LOCK_FUNCTION();
+};
+
+Mutex other;
+void fn() EXCLUSIVE_LOCKS_REQUIRED(other);
+
+void lockUnlock() EXCLUSIVE_LOCKS_REQUIRED(mu) {
+ MutexLockUnlock scope(&mu, &other);
+ fn();
+ x = 1; // expected-warning {{writing variable 'x' requires holding mutex 'mu' exclusively}}
+}
+
+} // end namespace ScopedUnlock
+
+
namespace TrylockFunctionTest {
class Foo {
Index: lib/Analysis/ThreadSafety.cpp
===================================================================
--- lib/Analysis/ThreadSafety.cpp
+++ lib/Analysis/ThreadSafety.cpp
@@ -41,6 +41,7 @@
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/ImmutableMap.h"
#include "llvm/ADT/Optional.h"
+#include "llvm/ADT/PointerIntPair.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
@@ -889,45 +890,74 @@
class ScopedLockableFactEntry : public FactEntry {
private:
- SmallVector<const til::SExpr *, 4> UnderlyingMutexes;
+ enum UnderlyingCapabilityKind {
+ UCK_Acquired, ///< Any kind of acquired capability.
+ UCK_ReleasedShared, ///< Shared capability that was released.
+ UCK_ReleasedExclusive, ///< Exclusive capability that was released.
+ };
+
+ using UnderlyingCapability =
+ llvm::PointerIntPair<const til::SExpr *, 2, UnderlyingCapabilityKind>;
+
+ SmallVector<UnderlyingCapability, 4> UnderlyingMutexes;
public:
ScopedLockableFactEntry(const CapabilityExpr &CE, SourceLocation Loc,
- const CapExprSet &Excl, const CapExprSet &Shrd)
+ const CapExprSet &Excl, const CapExprSet &Shrd,
+ const CapExprSet &ExclRel, const CapExprSet &ShrdRel)
: FactEntry(CE, LK_Exclusive, Loc, false) {
for (const auto &M : Excl)
- UnderlyingMutexes.push_back(M.sexpr());
+ UnderlyingMutexes.emplace_back(M.sexpr(), UCK_Acquired);
for (const auto &M : Shrd)
- UnderlyingMutexes.push_back(M.sexpr());
+ UnderlyingMutexes.emplace_back(M.sexpr(), UCK_Acquired);
+ for (const auto &M : ExclRel)
+ UnderlyingMutexes.emplace_back(M.sexpr(), UCK_ReleasedExclusive);
+ for (const auto &M : ShrdRel)
+ UnderlyingMutexes.emplace_back(M.sexpr(), UCK_ReleasedExclusive);
}
void
handleRemovalFromIntersection(const FactSet &FSet, FactManager &FactMan,
SourceLocation JoinLoc, LockErrorKind LEK,
ThreadSafetyHandler &Handler) const override {
- for (const auto *UnderlyingMutex : UnderlyingMutexes) {
- if (FSet.findLock(FactMan, CapabilityExpr(UnderlyingMutex, false))) {
+ for (const auto &UnderlyingMutex : UnderlyingMutexes) {
+ const auto *Entry = FSet.findLock(
+ FactMan, CapabilityExpr(UnderlyingMutex.getPointer(), false));
+ if ((UnderlyingMutex.getInt() == UCK_Acquired) == (Entry != nullptr)) {
// If this scoped lock manages another mutex, and if the underlying
// mutex is still held, then warn about the underlying mutex.
Handler.handleMutexHeldEndOfScope(
- "mutex", sx::toString(UnderlyingMutex), loc(), JoinLoc, LEK);
+ "mutex", sx::toString(UnderlyingMutex.getPointer()), loc(), JoinLoc,
+ LEK);
}
}
}
void handleLock(FactSet &FSet, FactManager &FactMan, const FactEntry &entry,
ThreadSafetyHandler &Handler,
StringRef DiagKind) const override {
- for (const auto *UnderlyingMutex : UnderlyingMutexes) {
- CapabilityExpr UnderCp(UnderlyingMutex, false);
+ for (const auto &UnderlyingMutex : UnderlyingMutexes) {
+ CapabilityExpr UnderCp(UnderlyingMutex.getPointer(), false);
- // We're relocking the underlying mutexes. Warn on double locking.
- if (FSet.findLock(FactMan, UnderCp)) {
- Handler.handleDoubleLock(DiagKind, UnderCp.toString(), entry.loc());
+ if (UnderlyingMutex.getInt() == UCK_Acquired) {
+ // We're relocking the underlying mutex. Warn on double locking.
+ if (FSet.findLock(FactMan, UnderCp)) {
+ Handler.handleDoubleLock(DiagKind, UnderCp.toString(), entry.loc());
+ } else {
+ FSet.removeLock(FactMan, !UnderCp);
+ FSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
+ UnderCp, entry.kind(), entry.loc()));
+ }
} else {
- FSet.removeLock(FactMan, !UnderCp);
- FSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
- UnderCp, entry.kind(), entry.loc()));
+ // We're removing the underlying mutex. Warn on double unlocking.
+ if (FSet.findLock(FactMan, UnderCp)) {
+ FSet.removeLock(FactMan, UnderCp);
+ FSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
+ !UnderCp, entry.kind(), entry.loc()));
+ } else {
+ Handler.handleUnmatchedUnlock(DiagKind, UnderCp.toString(),
+ entry.loc());
+ }
}
}
}
@@ -937,27 +967,55 @@
bool FullyRemove, ThreadSafetyHandler &Handler,
StringRef DiagKind) const override {
assert(!Cp.negative() && "Managing object cannot be negative.");
- for (const auto *UnderlyingMutex : UnderlyingMutexes) {
- CapabilityExpr UnderCp(UnderlyingMutex, false);
- auto UnderEntry = llvm::make_unique<LockableFactEntry>(
- !UnderCp, LK_Exclusive, UnlockLoc);
-
- if (FullyRemove) {
- // We're destroying the managing object.
- // Remove the underlying mutex if it exists; but don't warn.
- if (FSet.findLock(FactMan, UnderCp)) {
- FSet.removeLock(FactMan, UnderCp);
- FSet.addLock(FactMan, std::move(UnderEntry));
+ for (const auto &UnderlyingMutex : UnderlyingMutexes) {
+ CapabilityExpr UnderCp(UnderlyingMutex.getPointer(), false);
+
+ if (UnderlyingMutex.getInt() == UCK_Acquired) {
+ auto UnderEntry = llvm::make_unique<LockableFactEntry>(
+ !UnderCp, LK_Exclusive, UnlockLoc);
+
+ if (FullyRemove) {
+ // We're destroying the managing object.
+ // Remove the underlying mutex if it exists; but don't warn.
+ if (FSet.findLock(FactMan, UnderCp)) {
+ FSet.removeLock(FactMan, UnderCp);
+ FSet.addLock(FactMan, std::move(UnderEntry));
+ }
+ } else {
+ // We're releasing the underlying mutex, but not destroying the
+ // managing object. Warn on double unlocking.
+ if (!FSet.findLock(FactMan, UnderCp)) {
+ Handler.handleUnmatchedUnlock(DiagKind, UnderCp.toString(),
+ UnlockLoc);
+ } else {
+ FSet.removeLock(FactMan, UnderCp);
+ FSet.addLock(FactMan, std::move(UnderEntry));
+ }
}
} else {
- // We're releasing the underlying mutex, but not destroying the
- // managing object. Warn on dual release.
- if (!FSet.findLock(FactMan, UnderCp)) {
- Handler.handleUnmatchedUnlock(DiagKind, UnderCp.toString(),
- UnlockLoc);
+ LockKind kind = (UnderlyingMutex.getInt() == UCK_ReleasedExclusive)
+ ? LK_Exclusive
+ : LK_Shared;
+ auto UnderEntry =
+ llvm::make_unique<LockableFactEntry>(UnderCp, kind, UnlockLoc);
+
+ if (FullyRemove) {
+ // We're destroying the managing object.
+ // Lock the underlying mutex if not yet locked; but don't warn.
+ if (!FSet.findLock(FactMan, UnderCp)) {
+ FSet.removeLock(FactMan, !UnderCp);
+ FSet.addLock(FactMan, std::move(UnderEntry));
+ }
+ } else {
+ // We're locking the underlying mutex, but not destroying the
+ // managing object. Warn on double locking.
+ if (FSet.findLock(FactMan, UnderCp)) {
+ Handler.handleDoubleLock(DiagKind, UnderCp.toString(), UnlockLoc);
+ } else {
+ FSet.removeLock(FactMan, !UnderCp);
+ FSet.addLock(FactMan, std::move(UnderEntry));
+ }
}
- FSet.removeLock(FactMan, UnderCp);
- FSet.addLock(FactMan, std::move(UnderEntry));
}
}
if (FullyRemove)
@@ -1891,7 +1949,8 @@
std::back_inserter(SharedLocksToAdd));
Analyzer->addLock(FSet,
llvm::make_unique<ScopedLockableFactEntry>(
- Scp, MLoc, ExclusiveLocksToAdd, SharedLocksToAdd),
+ Scp, MLoc, ExclusiveLocksToAdd, SharedLocksToAdd,
+ ExclusiveLocksToRemove, SharedLocksToRemove),
CapDiagKind);
}
}
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