From 64b22cd00f3af5c07552188773f4ec159f68044b Mon Sep 17 00:00:00 2001
From: zesongw <zesong.wang@intel.com>
Date: Wed, 21 Jun 2023 07:45:40 +0800
Subject: [PATCH] [WebNN EP] Support Where Op (#16380)

### Description
Add Where Op for WebNN EP as ternary conditional operator.

---------

Co-authored-by: Dwayne Robinson <dwayner@microsoft.com>
---
 .../core/providers/webnn/builders/helper.h    |  1 +
 .../webnn/builders/impl/ternary_op_builder.cc | 61 +++++++++++++++++++
 .../webnn/builders/op_builder_factory.cc      |  4 ++
 .../webnn/builders/op_builder_factory.h       |  1 +
 4 files changed, 67 insertions(+)
 create mode 100644 onnxruntime/core/providers/webnn/builders/impl/ternary_op_builder.cc

diff --git a/onnxruntime/core/providers/webnn/builders/helper.h b/onnxruntime/core/providers/webnn/builders/helper.h
index 728317f595..7b11f852b8 100644
--- a/onnxruntime/core/providers/webnn/builders/helper.h
+++ b/onnxruntime/core/providers/webnn/builders/helper.h
@@ -140,6 +140,7 @@ static const InlinedHashMap<std::string, std::string> op_map = {
     {"Squeeze", "squeeze"},
     {"Transpose", "transpose"},
     {"Unsqueeze", "unsqueeze"},
+    {"Where", "elementwiseIf"},
 };
 
 inline bool CheckSingleOp(const std::string& op_type, const emscripten::val& wnn_builder_) {
diff --git a/onnxruntime/core/providers/webnn/builders/impl/ternary_op_builder.cc b/onnxruntime/core/providers/webnn/builders/impl/ternary_op_builder.cc
new file mode 100644
index 0000000000..b5e5600af0
--- /dev/null
+++ b/onnxruntime/core/providers/webnn/builders/impl/ternary_op_builder.cc
@@ -0,0 +1,61 @@
+// 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/model_builder.h"
+#include "core/providers/webnn/builders/op_builder_factory.h"
+#include "core/providers/webnn/builders/helper.h"
+
+#include "base_op_builder.h"
+
+namespace onnxruntime {
+namespace webnn {
+
+class TernaryOpBuilder : public BaseOpBuilder {
+  // Add operator related.
+ private:
+  Status AddToModelBuilderImpl(ModelBuilder& model_builder, const Node& node,
+                               const logging::Logger& logger) const override ORT_MUST_USE_RESULT;
+};
+
+// Add operator related.
+
+Status TernaryOpBuilder::AddToModelBuilderImpl(ModelBuilder& model_builder, const Node& node,
+                                               const logging::Logger& /* logger */) const {
+  const auto& op_type(node.OpType());
+  ORT_RETURN_IF(node.InputDefs().size() < 3, "Operator requires at least three inputs");
+
+  emscripten::val input0 = model_builder.GetOperand(node.InputDefs()[0]->Name());
+  emscripten::val input1 = model_builder.GetOperand(node.InputDefs()[1]->Name());
+  emscripten::val input2 = model_builder.GetOperand(node.InputDefs()[2]->Name());
+  emscripten::val output = emscripten::val::object();
+  if (op_type == "Where") {
+    output = model_builder.GetBuilder().call<emscripten::val>("elementwiseIf", input0, input1, input2);
+  } else {
+    return ORT_MAKE_STATUS(ONNXRUNTIME, INVALID_ARGUMENT,
+                           "TernaryOpBuilder::AddToModelBuilderImpl, unknown op: ", op_type);
+  }
+
+  model_builder.AddOperand(node.OutputDefs()[0]->Name(), std::move(output));
+  return Status::OK();
+}
+
+void CreateTernaryOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations) {
+  if (op_registrations.op_builder_map.find(op_type) != op_registrations.op_builder_map.cend())
+    return;
+
+  static std::vector<std::string> op_types =
+      {
+          "Where",
+      };
+
+  op_registrations.builders.push_back(std::make_unique<TernaryOpBuilder>());
+  for (const auto& type : op_types) {
+    op_registrations.op_builder_map.emplace(type, op_registrations.builders.back().get());
+  }
+}
+
+}  // namespace webnn
+}  // namespace onnxruntime
diff --git a/onnxruntime/core/providers/webnn/builders/op_builder_factory.cc b/onnxruntime/core/providers/webnn/builders/op_builder_factory.cc
index 77bc21561a..0a84fe07b8 100644
--- a/onnxruntime/core/providers/webnn/builders/op_builder_factory.cc
+++ b/onnxruntime/core/providers/webnn/builders/op_builder_factory.cc
@@ -37,6 +37,10 @@ static OpBuilderRegistrations CreateOpBuilderRegistrations() {
     CreateBinaryOpBuilder("Pow", op_registrations);
   }
 
+  {  // Ternary
+    CreateTernaryOpBuilder("Where", op_registrations);
+  }
+
   {  // Activations
     CreateActivationOpBuilder("Relu", op_registrations);
     CreateActivationOpBuilder("LeakyRelu", op_registrations);
diff --git a/onnxruntime/core/providers/webnn/builders/op_builder_factory.h b/onnxruntime/core/providers/webnn/builders/op_builder_factory.h
index e51d212e51..2dde66dff4 100644
--- a/onnxruntime/core/providers/webnn/builders/op_builder_factory.h
+++ b/onnxruntime/core/providers/webnn/builders/op_builder_factory.h
@@ -41,6 +41,7 @@ void CreateSliceOpBuilder(const std::string& op_type, OpBuilderRegistrations& op
 void CreateSoftmaxOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);
 void CreateSplitOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);
 void CreateSqueezeUnsqueezeOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);
+void CreateTernaryOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);
 void CreateTransposeOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);
 void CreateUnaryOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations);