Use singleton pattern to load OpenCL library.

mace/core/runtime/opencl/opencl_runtime.cc

@@ -308,8 +308,6 @@ OpenCLRuntime::OpenCLRuntime():
     precompiled_binary_storage_(nullptr),
     cache_storage_(nullptr),
     is_profiling_enabled_(false) {
-  LoadOpenCLLibrary();
-
   std::vector<cl::Platform> all_platforms;
   cl::Platform::get(&all_platforms);
   if (all_platforms.size() == 0) {
@@ -456,7 +454,6 @@ OpenCLRuntime::~OpenCLRuntime() {
   command_queue_.reset();
   context_.reset();
   device_.reset();
-  UnloadOpenCLLibrary();
 }
 
 cl::Context &OpenCLRuntime::context() { return *context_; }

mace/core/runtime/opencl/opencl_runtime.h

@@ -24,7 +24,6 @@
 
 #include "mace/core/future.h"
 #include "mace/core/runtime/opencl/cl2_header.h"
-#include "mace/core/runtime/opencl/opencl_wrapper.h"
 #include "mace/public/mace_runtime.h"
 #include "mace/utils/string_util.h"
 #include "mace/utils/timer.h"

mace/core/runtime/opencl/opencl_wrapper.h

-// Copyright 2018 Xiaomi, Inc.  All rights reserved.
-//
-// 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 MACE_CORE_RUNTIME_OPENCL_OPENCL_WRAPPER_H_
-#define MACE_CORE_RUNTIME_OPENCL_OPENCL_WRAPPER_H_
-
-namespace mace {
-
-// These functions are not thread-safe.
-void LoadOpenCLLibrary();
-void UnloadOpenCLLibrary();
-
-}  // namespace mace
-
-#endif  // MACE_CORE_RUNTIME_OPENCL_OPENCL_WRAPPER_H_