Support Cast op

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

@@ -45,6 +45,7 @@ static const InlinedHashMap<std::string, std::string> op_map = {
     {"LeakyRelu", "leakyRelu"},
     {"Sigmoid", "sigmoid"},
     {"Softmax", "softmax"},
+    {"Cast", "cast"},
     {"Clip", "clamp"},
     {"Conv", "conv2d"},
     {"ConvTranspose", "convTranspose2d"},

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

@@ -0,0 +1,78 @@
+// 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/webnn/builders/helper.h"
+#include "core/providers/webnn/builders/model_builder.h"
+#include "core/providers/webnn/builders/op_builder_factory.h"
+#include "core/providers/shared/utils/utils.h"
+
+#include "base_op_builder.h"
+
+namespace onnxruntime {
+namespace webnn {
+
+class CastOpBuilder : 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 logging::Logger& logger) const override;
+
+  int GetMinSupportedOpSet(const Node& node) const override;
+};
+
+// Add operator related.
+
+Status CastOpBuilder::AddToModelBuilderImpl(ModelBuilder& model_builder,
+                                            const Node& node,
+                                            const logging::Logger& logger) const {
+  const auto& input_name = node.InputDefs()[0]->Name();
+  emscripten::val input = model_builder.GetOperand(input_name);
+
+  NodeAttrHelper helper(node);
+  // We already checked the "to" type in IsOpSupportedImpl.
+  const auto to_type = helper.Get("to", ONNX_NAMESPACE::TensorProto_DataType_FLOAT);
+  std::string operand_type =
+      to_type == ONNX_NAMESPACE::TensorProto_DataType_FLOAT ? "float32" : "float16";
+
+  emscripten::val output =
+      model_builder.GetBuilder().call<emscripten::val>("cast", input, emscripten::val(operand_type));
+
+  model_builder.AddOperand(node.OutputDefs()[0]->Name(), std::move(output));
+  return Status::OK();
+}
+
+// Operator support related.
+
+int CastOpBuilder::GetMinSupportedOpSet(const Node& /* node */) const {
+  // Since opset 6, Cast uses attribute "to" as int type.
+  return 6;
+}
+
+bool CastOpBuilder::IsOpSupportedImpl(const InitializedTensorSet& initializers, const Node& node,
+                                      const logging::Logger& logger) const {
+  NodeAttrHelper helper(node);
+  // Check cast output type.
+  const auto to_type = helper.Get("to", ONNX_NAMESPACE::TensorProto_DataType_UNDEFINED);
+  if (!IsSupportedDataType(to_type)) {
+    LOGS(logger, VERBOSE) << "Invalid cast to type " << to_type
+                          << " . Current WebNN only support cast to float32 or float16.";
+    return false;
+  }
+
+  return true;
+}
+
+void CreateCastOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations) {
+  op_registrations.builders.push_back(std::make_unique<CastOpBuilder>());
+  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

@@ -36,6 +36,10 @@ static OpBuilderRegistrations CreateOpBuilderRegistrations() {
     CreateActivationOpBuilder("Sigmoid", op_registrations);
   }
 
+  {  // Cast
+    CreateCastOpBuilder("Cast", op_registrations);
+  }
+
   {  // Clip
     CreateClipOpBuilder("Clip", op_registrations);
   }

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

@@ -21,6 +21,7 @@ const InlinedHashMap<std::string, const IOpBuilder*>& GetOpBuilders();
 
 void CreateActivationOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);
 void CreateBinaryOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);
+void CreateCastOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);
 void CreateClipOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);
 void CreateConvOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);
 void CreateConcatOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);