[SYCL][Graph] Implementation of whole graph update

sycl/doc/design/CommandGraph.md

@@ -234,7 +234,9 @@ yet been implemented.
 
 ### Design Challenges
 
-Graph update faces significant design challenges in SYCL:
+#### Explicit Update
+
+Explicit updates of individual nodes faces significant design challenges in SYCL:
 
 * Lambda capture order is explicitly undefined in C++, so the user cannot reason
   about the indices of arguments captured by kernel lambdas.
@@ -256,9 +258,18 @@ can be used:
   extension](../extensions/proposed/sycl_ext_oneapi_free_function_kernels.asciidoc)
 * OpenCL interop kernels created from SPIR-V source at runtime.
 
-A possible future workaround lambda capture issues could be "Whole-Graph Update"
-where if we can guarantee that lambda capture order is the same across two
-different recordings we can then match parameter order when updating.
+A workaround for the lambda capture issues is the "Whole-Graph Update" feature.
+Since the lambda capture order is the same across two different recordings, we
+can match the parameter order when updating.
+
+#### Whole-Graph Update
+
+The current implementation of the whole-graph update feature relies on the
+assumption that both graphs should have a similar topology. Currently, the
+implementation only checks that both graphs have an identical number of nodes
+and that each node contains the same number of edges. Further investigation
+should be done to see if it is possible to add extra checks (e.g. check that the
+nodes and edges were added in the same order).
 
 ### Scheduler Integration
 

sycl/source/detail/graph_impl.cpp

@@ -757,8 +757,9 @@ void exec_graph_impl::createCommandBuffers(
 exec_graph_impl::exec_graph_impl(sycl::context Context,
                                  const std::shared_ptr<graph_impl> &GraphImpl,
                                  const property_list &PropList)
-    : MSchedule(), MGraphImpl(GraphImpl), MPiSyncPoints(), MContext(Context),
-      MRequirements(), MExecutionEvents(),
+    : MSchedule(), MGraphImpl(GraphImpl), MPiSyncPoints(),
+      MDevice(GraphImpl->getDevice()), MContext(Context), MRequirements(),
+      MExecutionEvents(),
       MIsUpdatable(PropList.has_property<property::graph::updatable>()) {
 
   // If the graph has been marked as updatable then check if the backend
@@ -1155,9 +1156,56 @@ void exec_graph_impl::duplicateNodes() {
   MNodeStorage.insert(MNodeStorage.begin(), NewNodes.begin(), NewNodes.end());
 }
 
+void exec_graph_impl::update(std::shared_ptr<graph_impl> GraphImpl) {
+
+  if (MDevice != GraphImpl->getDevice()) {
+    throw sycl::exception(
+        sycl::make_error_code(errc::invalid),
+        "Cannot update using a graph created with a different device.");
+  }
+  if (MContext != GraphImpl->getContext()) {
+    throw sycl::exception(
+        sycl::make_error_code(errc::invalid),
+        "Cannot update using a graph created with a different context.");
+  }
+
+  if (MNodeStorage.size() != GraphImpl->MNodeStorage.size()) {
+    throw sycl::exception(sycl::make_error_code(errc::invalid),
+                          "Cannot update using a graph with a different "
+                          "topology. Mismatch found in the number of nodes.");
+  } else {
+    for (uint32_t i = 0; i < MNodeStorage.size(); ++i) {
+      if (MNodeStorage[i]->MSuccessors.size() !=
+              GraphImpl->MNodeStorage[i]->MSuccessors.size() ||
+          MNodeStorage[i]->MPredecessors.size() !=
+              GraphImpl->MNodeStorage[i]->MPredecessors.size()) {
+        throw sycl::exception(
+            sycl::make_error_code(errc::invalid),
+            "Cannot update using a graph with a different topology. Mismatch "
+            "found in the number of edges.");
+      }
+
+      if (MNodeStorage[i]->MCGType != GraphImpl->MNodeStorage[i]->MCGType) {
+        throw sycl::exception(
+            sycl::make_error_code(errc::invalid),
+            "Cannot update using a graph with mismatched node types. Each pair "
+            "of nodes being updated must have the same type");
+      }
+    }
+  }
+
+  for (uint32_t i = 0; i < MNodeStorage.size(); ++i) {
+    MIDCache.insert(
+        std::make_pair(GraphImpl->MNodeStorage[i]->MID, MNodeStorage[i]));
+  }
+
+  update(GraphImpl->MNodeStorage);
+}
+
 void exec_graph_impl::update(std::shared_ptr<node_impl> Node) {
   this->update(std::vector<std::shared_ptr<node_impl>>{Node});
 }
+
 void exec_graph_impl::update(
     const std::vector<std::shared_ptr<node_impl>> Nodes) {
 
@@ -1598,9 +1646,7 @@ void executable_command_graph::finalizeImpl() {
 
 void executable_command_graph::update(
     const command_graph<graph_state::modifiable> &Graph) {
-  (void)Graph;
-  throw sycl::exception(sycl::make_error_code(errc::invalid),
-                        "Method not yet implemented");
+  impl->update(sycl::detail::getSyclObjImpl(Graph));
 }
 
 void executable_command_graph::update(const node &Node) {

sycl/source/detail/graph_impl.hpp

@@ -1281,6 +1281,10 @@ class exec_graph_impl {
   void createCommandBuffers(sycl::device Device,
                             std::shared_ptr<partition> &Partition);
 
+  /// Query for the device tied to this graph.
+  /// @return Device associated with graph.
+  sycl::device getDevice() const { return MDevice; }
+
   /// Query for the context tied to this graph.
   /// @return Context associated with graph.
   sycl::context getContext() const { return MContext; }
@@ -1320,6 +1324,7 @@ class exec_graph_impl {
     return MRequirements;
   }
 
+  void update(std::shared_ptr<graph_impl> GraphImpl);
   void update(std::shared_ptr<node_impl> Node);
   void update(const std::vector<std::shared_ptr<node_impl>> Nodes);
 
@@ -1408,6 +1413,8 @@ class exec_graph_impl {
   /// Map of nodes in the exec graph to the partition number to which they
   /// belong.
   std::unordered_map<std::shared_ptr<node_impl>, int> MPartitionNodes;
+  /// Device associated with this executable graph.
+  sycl::device MDevice;
   /// Context associated with this executable graph.
   sycl::context MContext;
   /// List of requirements for enqueueing this command graph, accumulated from