From bc8ffdb68ca93699080cf43f7d46a6a5cc0dba6f Mon Sep 17 00:00:00 2001
From: DeLesley Hutchins <delesley@google.com>
Date: Thu, 16 Feb 2012 17:03:24 +0000
Subject: [PATCH] Thread-Safety: added support for 'this' as a lock expression.

llvm-svn: 150700
---
 clang/lib/Analysis/ThreadSafety.cpp           | 10 +++++--
 .../SemaCXX/warn-thread-safety-analysis.cpp   | 30 +++++++++++++++++++
 2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/clang/lib/Analysis/ThreadSafety.cpp b/clang/lib/Analysis/ThreadSafety.cpp
index f4386538d7ae..5a08ec6b21de 100644
--- a/clang/lib/Analysis/ThreadSafety.cpp
+++ b/clang/lib/Analysis/ThreadSafety.cpp
@@ -62,11 +62,11 @@ namespace {
 ///
 /// Clang introduces an additional wrinkle, which is that it is difficult to
 /// derive canonical expressions, or compare expressions directly for equality.
-/// Thus, we identify a mutex not by an Expr, but by the set of named
+/// Thus, we identify a mutex not by an Expr, but by the list of named
 /// declarations that are referenced by the Expr.  In other words,
 /// x->foo->bar.mu will be a four element vector with the Decls for
 /// mu, bar, and foo, and x.  The vector will uniquely identify the expression
-/// for all practical purposes.
+/// for all practical purposes.  Null is used to denote 'this'.
 ///
 /// Note we will need to perform substitution on "this" and function parameter
 /// names when constructing a lock expression.
@@ -122,8 +122,10 @@ class MutexID {
     } else if (isa<CXXThisExpr>(Exp)) {
       if (Parent)
         buildMutexID(Parent, D, 0, 0, 0);
-      else
+      else {
+        DeclSeq.push_back(0);  // Use 0 to represent 'this'.
         return;  // mutexID is still valid in this case
+      }
     } else if (UnaryOperator *UOE = dyn_cast<UnaryOperator>(Exp))
       buildMutexID(UOE->getSubExpr(), D, Parent, NumArgs, FunArgs);
     else if (CastExpr *CE = dyn_cast<CastExpr>(Exp))
@@ -233,6 +235,8 @@ public:
   /// We do not want to output the entire expression text for security reasons.
   StringRef getName() const {
     assert(isValid());
+    if (!DeclSeq.front())
+      return "this";  // Use 0 to represent 'this'.
     return DeclSeq.front()->getName();
   }
 
diff --git a/clang/test/SemaCXX/warn-thread-safety-analysis.cpp b/clang/test/SemaCXX/warn-thread-safety-analysis.cpp
index e0fde6b2555c..20d816a41d8c 100644
--- a/clang/test/SemaCXX/warn-thread-safety-analysis.cpp
+++ b/clang/test/SemaCXX/warn-thread-safety-analysis.cpp
@@ -2049,5 +2049,35 @@ void test() {
     // expected-warning {{calling function 'foo' requires exclusive lock on 'mu_'}}
 }
 
+} // end namespace FunctionDefinitionTest
+
+
+namespace SelfLockingTest {
+
+class LOCKABLE MyLock {
+public:
+  int foo GUARDED_BY(this);
+
+  void lock()   EXCLUSIVE_LOCK_FUNCTION();
+  void unlock() UNLOCK_FUNCTION();
+
+  void doSomething() {
+    this->lock();  // allow 'this' as a lock expression
+    foo = 0;
+    doSomethingElse();
+    this->unlock();
+  }
+
+  void doSomethingElse() EXCLUSIVE_LOCKS_REQUIRED(this) {
+    foo = 1;
+  };
+
+  void test() {
+    foo = 2;  // \
+      // expected-warning {{writing variable 'foo' requires locking 'this' exclusively}}
+  }
 };
 
+} // end namespace SelfLockingTest
+
+