[EP ABI] Update Graph_GetGraphView() implementation

[chilo-ms]

Description

In some cases, e.g. when model has a node that produces output consumed by multiple nodes, calling the current implementation of Graph_GetGraphView() to get a subgraph returns incorrect OrtGraph.

This PR fixes the issue.

• Original graph:

  

• Incorrect graph after calling Graph_GetGraphView() to get the subgraph:

  It includes three of the nodes from the original graph.
  The topk_indices is the output of the TopK and it shouldn't be added as a graph input shown in the graph below.
  The API implementation has issue handling this case.
  If we feed this subgraph into TRT parser, it would fail to parse the graph.

  

• Correct graph after calling Graph_GetGraphView() to get the subgraph:

  It includes three of the nodes from the original graph.
  The topk_indices now is not added as a graph input. Instead, the topk_indices is added as a graph output which is expected as Mod is in another subgraph that consumes it, so this subgraph has to make topk_indices a graph output.

  

Motivation and Context

[github-actions]

You can commit the suggested changes from lintrunner.

[adrianlizarraga]

Hi Chi, I had some initial comments.

Also, I think there is existing code that seems to do something very similar:

onnxruntime/onnxruntime/core/providers/partitioning_utils.cc

Lines 287 to 368 in 8f8069d

	std::unique_ptr<ComputeCapability> MakeComputeCapability(const GraphViewer& graph_viewer,
	const std::vector<const Node*>& group,
	const GenerateMetadefNameFn& generate_metadef_name,
	const std::string& execution_provider_name,
	bool drop_constant_initializers) {
	std::unordered_set<const Node*> node_set;
	node_set.reserve(group.size());
	node_set.insert(group.cbegin(), group.cend());
	std::unique_ptr<IndexedSubGraph> sub_graph = std::make_unique<IndexedSubGraph>();
	std::unordered_set<const NodeArg*> node_outputs;
	std::unordered_set<const NodeArg*> subgraph_inputs;
	std::unordered_set<const NodeArg*> subgraph_outputs;
	std::vector<const NodeArg*> ordered_subgraph_inputs;
	std::vector<const NodeArg*> ordered_subgraph_outputs;
	const auto& graph_output_list = graph_viewer.GetOutputs();
	std::unordered_set<const NodeArg*> graph_outputs(graph_output_list.cbegin(), graph_output_list.cend());
	for (const Node* node : group) {
	sub_graph->nodes.push_back(node->Index());
	for (const auto* input : node->InputDefs()) {
	if (!input->Exists()) {
	// skip the placeholder inputs
	continue;
	}
	// if the node input was not produced by this subgraph, add it to the subgraph inputs.
	if (!Contains(node_outputs, input)) {
	if (!Contains(subgraph_inputs, input)) {
	subgraph_inputs.insert(input);
	ordered_subgraph_inputs.push_back(input);
	}
	}
	}
	const auto& output_defs = node->OutputDefs();
	for (const auto* output_def : output_defs) {
	node_outputs.insert(output_def);
	// if output is overall graph output we need to produce it.
	if (Contains(graph_outputs, output_def)) {
	ordered_subgraph_outputs.push_back(output_def);
	}
	}
	// if output connects to a node not in this subgraph we need to add it
	// unless it was already added as an overall graph output,
	for (auto it = node->OutputEdgesBegin(), end = node->OutputEdgesEnd(); it != end; ++it) {
	if (!Contains(node_set, &it->GetNode())) {
	const auto* output_def = output_defs[it->GetSrcArgIndex()];
	if (!Contains(subgraph_outputs, output_def) && !Contains(graph_outputs, output_def)) {
	subgraph_outputs.insert(output_def);
	ordered_subgraph_outputs.push_back(output_def);
	}
	}
	}
	}
	// Assign inputs and outputs to subgraph's meta_def
	auto meta_def = std::make_unique<::onnxruntime::IndexedSubGraph::MetaDef>();
	meta_def->name = generate_metadef_name();
	meta_def->domain = execution_provider_name;
	meta_def->since_version = 1;
	meta_def->status = ONNX_NAMESPACE::EXPERIMENTAL;
	for (const auto& input : ordered_subgraph_inputs) {
	if (drop_constant_initializers && graph_viewer.IsConstantInitializer(input->Name(), true)) {
	continue;
	}
	meta_def->inputs.push_back(input->Name());
	}
	for (const auto& output : ordered_subgraph_outputs) {
	meta_def->outputs.push_back(output->Name());
	}
	sub_graph->SetMetaDef(std::move(meta_def));
	return std::make_unique<ComputeCapability>(std::move(sub_graph));
	}

Since that code has been tested, perhaps there's some way to reuse some of the implementation in some way? Just fyi.

[adrianlizarraga]

nit: Could these be std::string_view to avoid copies? Would probably need to convert to std::string only when pushing into meta_def->constant_initializers. (or keep it as string and do a move).

[adrianlizarraga]

Do we need to skip this input if !input->Exists() (i.e., for missing optional inputs).