diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index 8e42040..dbc5cec 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -1500,7 +1500,7 @@
   Thread* const self = Thread::Current();
   JavaVMExt* const vm = Runtime::Current()->GetJavaVM();
   for (const ClassLoaderData& data : class_loaders_) {
-    vm->DecodeWeakGlobalDuringShutdown(self, data.weak_root);
+    vm->DeleteWeakGlobalRef(self, data.weak_root);
     delete data.allocator;
     delete data.class_table;
   }
@@ -4186,6 +4186,8 @@
     data.allocator = Runtime::Current()->CreateLinearAlloc();
     class_loaders_.push_back(data);
     // Don't already have a class table, add it to the class loader.
+    CHECK(class_loader->GetClassTable() == nullptr);
+    CHECK(class_loader->GetAllocator() == nullptr);
     class_loader->SetClassTable(data.class_table);
     class_loader->SetAllocator(data.allocator);
   }
diff --git a/runtime/class_linker.h b/runtime/class_linker.h
index f705330..739403f 100644
--- a/runtime/class_linker.h
+++ b/runtime/class_linker.h
@@ -560,7 +560,7 @@
 
  private:
   struct ClassLoaderData {
-    jobject weak_root;  // Weak root to enable class unloading.
+    jweak weak_root;  // Weak root to enable class unloading.
     ClassTable* class_table;
     LinearAlloc* allocator;
   };
diff --git a/runtime/jit/jit_instrumentation.cc b/runtime/jit/jit_instrumentation.cc
index 4f4a97f..e9c16c1 100644
--- a/runtime/jit/jit_instrumentation.cc
+++ b/runtime/jit/jit_instrumentation.cc
@@ -115,30 +115,8 @@
   }
 }
 
-class WaitForCompilationToFinishTask FINAL : public Task {
- public:
-  WaitForCompilationToFinishTask() : barrier_(0) {}
-
-  void Wait(Thread* self) {
-    barrier_.Increment(self, 1);
-  }
-
-  void Run(Thread* self ATTRIBUTE_UNUSED) OVERRIDE {}
-
-  void Finalize() OVERRIDE {
-    // Do this in Finalize since Finalize is called after Run by the thread pool.
-    barrier_.Pass(Thread::Current());
-  }
-
- private:
-  Barrier barrier_;
-  DISALLOW_COPY_AND_ASSIGN(WaitForCompilationToFinishTask);
-};
-
 void JitInstrumentationCache::WaitForCompilationToFinish(Thread* self) {
-  std::unique_ptr<WaitForCompilationToFinishTask> task(new WaitForCompilationToFinishTask);
-  thread_pool_->AddTask(self, task.get());
-  task->Wait(self);
+  thread_pool_->Wait(self, false, false);
 }
 
 }  // namespace jit
diff --git a/runtime/runtime.cc b/runtime/runtime.cc
index 8cba1a9..1f447d0 100644
--- a/runtime/runtime.cc
+++ b/runtime/runtime.cc
@@ -1790,6 +1790,9 @@
 }
 
 LinearAlloc* Runtime::CreateLinearAlloc() {
+  // For 64 bit compilers, it needs to be in low 4GB in the case where we are cross compiling for a
+  // 32 bit target. In this case, we have 32 bit pointers in the dex cache arrays which can't hold
+  // when we have 64 bit ArtMethod pointers.
   return (IsAotCompiler() && Is64BitInstructionSet(kRuntimeISA))
       ? new LinearAlloc(low_4gb_arena_pool_.get())
       : new LinearAlloc(arena_pool_.get());