add appropriate memory barriers to double-checked locking code

src/classpath-openjdk.cpp

@@ -2120,13 +2120,20 @@ setProperty(Thread* t, object method, object properties,
 object
 interruptLock(Thread* t, object thread)
 {
-  if (threadInterruptLock(t, thread) == 0) {
+  object lock = threadInterruptLock(t, thread);
+
+  loadMemoryBarrier();
+
+  if (lock == 0) {
     PROTECT(t, thread);
     ACQUIRE(t, t->m->referenceLock);
 
     if (threadInterruptLock(t, thread) == 0) {
       object head = makeMonitorNode(t, 0, 0);
       object lock = makeMonitor(t, 0, 0, 0, head, head, 0);
+
+      storeStoreMemoryBarrier();
+
       set(t, thread, ThreadInterruptLock, lock);
     }
   }

src/compile.cpp

@@ -9586,6 +9586,8 @@ compileVirtualThunk(MyThread* t, unsigned index, unsigned* size)
 uintptr_t
 virtualThunk(MyThread* t, unsigned index)
 {
+  ACQUIRE(t, t->m->classLock);
+
   if (root(t, VirtualThunks) == 0
       or wordArrayLength(t, root(t, VirtualThunks)) <= index * 2)
   {
@@ -9598,16 +9600,12 @@ virtualThunk(MyThread* t, unsigned index)
     setRoot(t, VirtualThunks, newArray);
   }
 
-  if (wordArrayBody(t, root(t, VirtualThunks), index * 2) == 0) {
-    ACQUIRE(t, t->m->classLock);
-
   if (wordArrayBody(t, root(t, VirtualThunks), index * 2) == 0) {
     unsigned size;
     uintptr_t thunk = compileVirtualThunk(t, index, &size);
     wordArrayBody(t, root(t, VirtualThunks), index * 2) = thunk;
     wordArrayBody(t, root(t, VirtualThunks), (index * 2) + 1) = size;
   }
-  }
 
   return wordArrayBody(t, root(t, VirtualThunks), index * 2);
 }

src/jnienv.cpp

@@ -509,7 +509,11 @@ findMethod(Thread* t, jclass c, const char* name, const char* spec)
 jint
 methodID(Thread* t, object method)
 {
-  if (methodNativeID(t, method) == 0) {
+  int id = methodNativeID(t, method);
+
+  loadMemoryBarrier();
+
+  if (id == 0) {
     PROTECT(t, method);
 
     ACQUIRE(t, t->m->referenceLock);
@@ -517,6 +521,9 @@ methodID(Thread* t, object method)
     if (methodNativeID(t, method) == 0) {
       setRoot(t, Machine::JNIMethodTable, vectorAppend
               (t, root(t, Machine::JNIMethodTable), method));
+
+      storeStoreMemoryBarrier();
+
       methodNativeID(t, method) = vectorSize
         (t, root(t, Machine::JNIMethodTable));
     }
@@ -1164,7 +1171,11 @@ CallStaticVoidMethod(Thread* t, jclass c, jmethodID m, ...)
 jint
 fieldID(Thread* t, object field)
 {
-  if (fieldNativeID(t, field) == 0) {
+  int id = fieldNativeID(t, field);
+
+  loadMemoryBarrier();
+
+  if (id == 0) {
     PROTECT(t, field);
 
     ACQUIRE(t, t->m->referenceLock);
@@ -1172,6 +1183,9 @@ fieldID(Thread* t, object field)
     if (fieldNativeID(t, field) == 0) {
       setRoot(t, Machine::JNIFieldTable, vectorAppend
               (t, root(t, Machine::JNIFieldTable), field));
+
+      storeStoreMemoryBarrier();
+
       fieldNativeID(t, field) = vectorSize(t, root(t, Machine::JNIFieldTable));
     }
   }

src/machine.cpp

@@ -3677,7 +3677,11 @@ classNeedsInit(Thread* t, object c)
 bool
 preInitClass(Thread* t, object c)
 {
-  if (classVmFlags(t, c) & NeedInitFlag) {
+  int flags = classVmFlags(t, c);
+
+  loadMemoryBarrier();
+
+  if (flags & NeedInitFlag) {
     PROTECT(t, c);
     ACQUIRE(t, t->m->classLock);
 

src/machine.h

@@ -3619,7 +3619,11 @@ getClassRuntimeData(Thread* t, object c)
 inline object
 getMethodRuntimeData(Thread* t, object method)
 {
-  if (methodRuntimeDataIndex(t, method) == 0) {
+  int index = methodRuntimeDataIndex(t, method);
+
+  loadMemoryBarrier();
+
+  if (index == 0) {
     PROTECT(t, method);
 
     ACQUIRE(t, t->m->classLock);
@@ -3630,6 +3634,8 @@ getMethodRuntimeData(Thread* t, object method)
       setRoot(t, Machine::MethodRuntimeDataTable, vectorAppend
               (t, root(t, Machine::MethodRuntimeDataTable), runtimeData));
 
+      storeStoreMemoryBarrier();
+
       methodRuntimeDataIndex(t, method) = vectorSize
         (t, root(t, Machine::MethodRuntimeDataTable));
     }
@@ -3645,6 +3651,9 @@ getJClass(Thread* t, object c)
   PROTECT(t, c);
 
   object jclass = classRuntimeDataJclass(t, getClassRuntimeData(t, c));
+
+  loadMemoryBarrier();
+
   if (jclass == 0) {
     ACQUIRE(t, t->m->classLock);
 
@@ -3652,6 +3661,8 @@ getJClass(Thread* t, object c)
     if (jclass == 0) {
       jclass = t->m->classpath->makeJclass(t, c);
 
+      storeStoreMemoryBarrier();
+      
       set(t, getClassRuntimeData(t, c), ClassRuntimeDataJclass, jclass);
     }
   }