[WebNN EP] Support Shape op (#16282)

Since WebNN API doesn't support shape op, in the WebNN EP, we calculate
the ONNX Shape node output and pass the values to a WebNN's constant +
slice as workaround.

onnxruntime/core/providers/webnn/builders/helper.h

@@ -135,6 +135,7 @@ static const InlinedHashMap<std::string, std::string> op_map = {
     {"ReduceMean", "reduceMean"},
     {"Reshape", "reshape"},
     {"Resize", "resample2d"},
+    {"Shape", "slice"},
     {"Split", "split"},
     {"Transpose", "transpose"},
     {"Unsqueeze", "unsqueeze"},

onnxruntime/core/providers/webnn/builders/impl/shape_op_builder.cc

@@ -0,0 +1,93 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Copyright (c) Intel Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+#include "core/providers/common.h"
+#include "core/providers/shared/utils/utils.h"
+#include "core/providers/webnn/builders/helper.h"
+#include "core/providers/webnn/builders/model_builder.h"
+#include "core/providers/webnn/builders/op_builder_factory.h"
+
+#include "base_op_builder.h"
+
+namespace onnxruntime {
+namespace webnn {
+
+class ShapeOpBuilder : public BaseOpBuilder {
+  // Add operator related.
+ private:
+  Status AddToModelBuilderImpl(ModelBuilder& model_builder, const Node& node,
+                               const logging::Logger& logger) const override ORT_MUST_USE_RESULT;
+
+  // Operator support related.
+ private:
+  bool IsOpSupportedImpl(const InitializedTensorSet& /* initializers */, const Node& node,
+                         const WebnnDeviceType device_type, const logging::Logger& logger) const override;
+};
+
+Status ShapeOpBuilder::AddToModelBuilderImpl(ModelBuilder& model_builder,
+                                             const Node& node,
+                                             const logging::Logger& logger) const {
+  const auto& input_defs = node.InputDefs();
+  std::vector<int64_t> input_shape;
+  ORT_RETURN_IF_NOT(GetShape(*input_defs[0], input_shape, logger), "Cannot get shape");
+  const auto rank = static_cast<int32_t>(input_shape.size());
+
+  emscripten::val desc = emscripten::val::object();
+  desc.set("type", emscripten::val("int64"));
+  emscripten::val dims = emscripten::val::array();
+  dims.call<void>("push", rank);
+  desc.set("dimensions", dims);
+  emscripten::val shape_buffer = emscripten::val::global("BigInt64Array").new_(emscripten::val::array(input_shape));
+  emscripten::val shape_constant = model_builder.GetBuilder().call<emscripten::val>("constant", desc, shape_buffer);
+
+  NodeAttrHelper helper(node);
+  auto true_start = helper.Get("start", 0);
+  auto true_end = helper.Get("end", rank);
+
+  // Deal with negative(s) and clamp.
+  true_start = std::clamp(true_start + (true_start < 0 ? rank : 0), 0, rank);
+  true_end = std::clamp(true_end + (true_end < 0 ? rank : 0), true_start, rank);
+  auto slice_length = true_end - true_start;
+
+  emscripten::val starts = emscripten::val::array();
+  starts.call<void>("push", true_start);
+  emscripten::val sizes = emscripten::val::array();
+  sizes.call<void>("push", slice_length);
+
+  // Since WebNN doesn't support Shape op, we use constant + slice ops as workaround.
+  emscripten::val output = model_builder.GetBuilder().call<emscripten::val>("slice", shape_constant, starts, sizes);
+
+  model_builder.AddOperand(node.OutputDefs()[0]->Name(), std::move(output));
+  return Status::OK();
+}
+
+// Operator support related.
+
+bool ShapeOpBuilder::IsOpSupportedImpl(const InitializedTensorSet& /* initializers */,
+                                       const Node& node,
+                                       const WebnnDeviceType device_type,
+                                       const logging::Logger& logger) const {
+  const auto& input_defs = node.InputDefs();
+  std::vector<int64_t> input_shape;
+  if (!GetShape(*input_defs[0], input_shape, logger))
+    return false;
+
+  int32_t output_type = ONNX_NAMESPACE::TensorProto_DataType_INT64;
+  if (!IsSupportedDataType(output_type, device_type)) {
+    LOGS(logger, VERBOSE) << "[" << node.OpType()
+                          << "] Output type: [" << output_type
+                          << "] is not supported for now";
+    return false;
+  }
+
+  return true;
+}
+
+void CreateShapeOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations) {
+  op_registrations.builders.push_back(std::make_unique<ShapeOpBuilder>());
+  op_registrations.op_builder_map.emplace(op_type, op_registrations.builders.back().get());
+}
+
+}  // namespace webnn
+}  // namespace onnxruntime

onnxruntime/core/providers/webnn/builders/op_builder_factory.cc

@@ -110,6 +110,10 @@ static OpBuilderRegistrations CreateOpBuilderRegistrations() {
     CreateResizeOpBuilder("Resize", op_registrations);
   }
 
+  {  // Shape
+    CreateShapeOpBuilder("Shape", op_registrations);
+  }
+
   {  // Slice
     CreateSliceOpBuilder("Slice", op_registrations);
   }

onnxruntime/core/providers/webnn/builders/op_builder_factory.h

@@ -36,6 +36,7 @@ void CreatePoolOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_
 void CreateReductionOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);
 void CreateReshapeOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);
 void CreateResizeOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);
+void CreateShapeOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);
 void CreateSliceOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);
 void CreateSoftmaxOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);
 void CreateSplitOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);