Support loading shared libraries for custom operators

- Add a new command line option to allow users to specify a custom
  defined dll library
- Add a custom registry to store all registered libraries
- Add a dummy example (custom_op_example.cpp) for demonstrating this new
  feature

Signed-off-by: Jerry Ge <jerry.ge@arm.com>
Change-Id: I7c360835933f77e33fcbd772cabfe01d82282d47

3 files changed, 127 insertions, 0 deletions

diff --git a/reference_model/include/custom_op_interface.h b/reference_model/include/custom_op_interface.h
new file mode 100644
index 0000000..aea9086
--- /dev/null
+++ b/reference_model/include/custom_op_interface.h
@@ -0,0 +1,38 @@
+// Copyright (c) 2023, ARM Limited.
+//
+//    Licensed under the Apache License, Version 2.0 (the "License");
+//    you may not use this file except in compliance with the License.
+//    You may obtain a copy of the License at
+//
+//         http://www.apache.org/licenses/LICENSE-2.0
+//
+//    Unless required by applicable law or agreed to in writing, software
+//    distributed under the License is distributed on an "AS IS" BASIS,
+//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//    See the License for the specific language governing permissions and
+//    limitations under the License.
+
+#ifndef CUSTOMOPINTERFACE_H
+#define CUSTOMOPINTERFACE_H
+
+#include "tensor.h"
+#include <vector>
+
+using namespace tosa;
+
+namespace TosaReference
+{
+class CustomOpInterface
+{
+public:
+    CustomOpInterface()                                       = default;
+    virtual std::string getDomainName() const                 = 0;
+    virtual std::string getOperatorName() const               = 0;
+    virtual int eval(std::vector<TosaReference::Tensor*>& input_tensors,
+                     std::vector<TosaReference::Tensor*>& output_tensors,
+                     const std::string& implementation_attrs) = 0;
+    virtual std::string getVersion() const                    = 0;
+};
+}    // namespace TosaReference
+
+#endif
diff --git a/reference_model/include/custom_registry.h b/reference_model/include/custom_registry.h
new file mode 100644
index 0000000..f1a9b8c
--- /dev/null
+++ b/reference_model/include/custom_registry.h
@@ -0,0 +1,88 @@
+// Copyright (c) 2023, ARM Limited.
+//
+//    Licensed under the Apache License, Version 2.0 (the "License");
+//    you may not use this file except in compliance with the License.
+//    You may obtain a copy of the License at
+//
+//         http://www.apache.org/licenses/LICENSE-2.0
+//
+//    Unless required by applicable law or agreed to in writing, software
+//    distributed under the License is distributed on an "AS IS" BASIS,
+//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//    See the License for the specific language governing permissions and
+//    limitations under the License.
+
+#ifndef CUSTOMREGISTRY_H
+#define CUSTOMREGISTRY_H
+
+#include "custom_op_interface.h"
+#include <dlfcn.h>
+#include <unordered_map>
+
+using namespace tosa;
+
+namespace TosaReference
+{
+
+typedef CustomOpInterface* (*op_creation_function_t)();
+typedef int (*registration_callback_t)(const std::string& domain_name,
+                                       const std::string& operator_name,
+                                       const op_creation_function_t& op_creation_function);
+
+class MasterRegistry
+{
+public:
+    static int register_function(const std::string& domain_name,
+                                 const std::string& operator_name,
+                                 const op_creation_function_t& op_creation_function)
+    {
+        std::string unique_id    = domain_name + "::" + operator_name;
+        MasterRegistry& instance = get_instance();
+        if (instance.op_creation_map.find(unique_id) != instance.op_creation_map.end())
+        {
+            std::cout << std::endl;
+            printf("domain_name: %s and operator_name: %s pair has already been registered", domain_name.c_str(),
+                   operator_name.c_str());
+            return 1;
+        }
+        instance.op_creation_map[unique_id] = op_creation_function;
+        return 0;
+    }
+
+    static MasterRegistry& get_instance()
+    {
+        static MasterRegistry instance;
+        return instance;
+    }
+
+    MasterRegistry(const MasterRegistry&) = delete;
+    void operator=(const MasterRegistry&) = delete;
+
+    std::unordered_map<std::string, op_creation_function_t> get_ops() const
+    {
+        return op_creation_map;
+    }
+
+    static op_creation_function_t get_op(const std::string& domain_name, const std::string& operator_name)
+    {
+        std::string unique_id    = domain_name + "::" + operator_name;
+        MasterRegistry& instance = get_instance();
+        auto all_ops_map         = instance.get_ops();
+        if (all_ops_map.find(unique_id) == all_ops_map.end())
+        {
+            return nullptr;
+        }
+        else
+        {
+            op_creation_function_t& op_creation_function = all_ops_map[unique_id];
+            return op_creation_function;
+        }
+    }
+
+private:
+    MasterRegistry() = default;
+    std::unordered_map<std::string, op_creation_function_t> op_creation_map;
+};
+}    // namespace TosaReference
+
+#endif
diff --git a/reference_model/include/func_config.h b/reference_model/include/func_config.h
index 22e7e2c..97afa82 100644
--- a/reference_model/include/func_config.h
+++ b/reference_model/include/func_config.h
@@ -54,6 +54,7 @@ struct func_config_t
     uint32_t dump_intermediates                    = 0;
     uint32_t initialize_variable_tensor_from_numpy = 0;
     std::string fp_format                          = "0.5";
+    std::string custom_op_lib_path                 = "";
     uint32_t precise_mode                          = 0;
     bool abs_mode                                  = 0;        // set in main as second run of precise_mode
     bool float_is_big_endian                       = false;    // Set in arith_util.h by float_is_big_endian()