[SYCL][Graph] Fix queue recording barrier to different graphs

Recording barrier submissions to from the same queue to a different
graph current produces the following error with added regression test:

```
Terminate called after throwing an instance of 'sycl::_V1::exception'
  what():  Graph nodes cannot depend on events from another graph.
```

This is because the queue implementation doesn't clear all the
state around what the last queue submission was between graph
recordings.

Fixed by clearing all members of the barrier book keeping struct
in the queue.

Author: EwanC

sycl/source/detail/queue_impl.hpp

@@ -732,7 +732,7 @@ class queue_impl {
       std::shared_ptr<ext::oneapi::experimental::detail::graph_impl> Graph) {
     std::lock_guard<std::mutex> Lock(MMutex);
     MGraph = Graph;
-    MExtGraphDeps.LastEventPtr = nullptr;
+    MExtGraphDeps.reset();
   }
 
   std::shared_ptr<ext::oneapi::experimental::detail::graph_impl>
@@ -938,6 +938,12 @@ class queue_impl {
     // ordering
     std::vector<EventImplPtr> UnenqueuedCmdEvents;
     EventImplPtr LastBarrier;
+
+    void reset() {
+      LastEventPtr = nullptr;
+      UnenqueuedCmdEvents.clear();
+      LastBarrier = nullptr;
+    }
   } MDefaultGraphDeps, MExtGraphDeps;
 
   const bool MIsInorder;

sycl/unittests/Extensions/CommandGraph/Regressions.cpp

@@ -58,3 +58,30 @@ TEST_F(CommandGraphTest, AccessorModeRegression) {
   EXPECT_EQ(NodeC.get_predecessors().size(), 0ul);
   EXPECT_EQ(NodeC.get_successors().size(), 0ul);
 }
+
+TEST_F(CommandGraphTest, QueueRecordBarrierMultipleGraph) {
+  // Test that using barriers recorded from the same queue to
+  // different graphs.
+
+  Graph.begin_recording(Queue);
+  auto NodeKernel = Queue.submit(
+      [&](sycl::handler &cgh) { cgh.single_task<TestKernel<>>([]() {}); });
+  Queue.ext_oneapi_submit_barrier({NodeKernel});
+  Graph.end_recording(Queue);
+
+  experimental::command_graph<experimental::graph_state::modifiable> GraphB{
+      Queue};
+  GraphB.begin_recording(Queue);
+  auto NodeKernelB = Queue.submit(
+      [&](sycl::handler &cgh) { cgh.single_task<TestKernel<>>([]() {}); });
+  Queue.ext_oneapi_submit_barrier({NodeKernelB});
+  GraphB.end_recording(Queue);
+
+  experimental::command_graph<experimental::graph_state::modifiable> GraphC{
+      Queue};
+  GraphC.begin_recording(Queue);
+  auto NodeKernelC = Queue.submit(
+      [&](sycl::handler &cgh) { cgh.single_task<TestKernel<>>([]() {}); });
+  Queue.ext_oneapi_submit_barrier();
+  GraphC.end_recording(Queue);
+}