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/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 ORC_DISPATCH_HH
#define ORC_DISPATCH_HH
#include <utility>
#include <vector>
#include "CpuInfoUtil.hh"
namespace orc {
enum class DispatchLevel : int {
// These dispatch levels, corresponding to instruction set features,
// are sorted in increasing order of preference.
NONE = 0,
AVX512,
MAX
};
/**
* A facility for dynamic dispatch according to available DispatchLevel.
*
* Typical use:
*
* static void my_function_default(...);
* static void my_function_avx512(...);
*
* struct MyDynamicFunction {
* using FunctionType = decltype(&my_function_default);
*
* static std::vector<std::pair<DispatchLevel, FunctionType>> implementations() {
* return {
* { DispatchLevel::NONE, my_function_default }
* #if defined(ORC_HAVE_RUNTIME_AVX512)
* , { DispatchLevel::AVX512, my_function_avx512 }
* #endif
* };
* }
* };
*
* void my_function(...) {
* static DynamicDispatch<MyDynamicFunction> dispatch;
* return dispatch.func(...);
* }
*/
template <typename DynamicFunction>
class DynamicDispatch {
protected:
using FunctionType = typename DynamicFunction::FunctionType;
using Implementation = std::pair<DispatchLevel, FunctionType>;
public:
DynamicDispatch() {
Resolve(DynamicFunction::implementations());
}
FunctionType func = {};
protected:
// Use the Implementation with the highest DispatchLevel
void Resolve(const std::vector<Implementation>& implementations) {
Implementation cur{DispatchLevel::NONE, {}};
for (const auto& impl : implementations) {
if (impl.first >= cur.first && levelSupported(impl.first)) {
// Higher (or same) level than current
cur = impl;
}
}
if (!cur.second) {
throw InvalidArgument("No appropriate implementation found");
}
func = cur.second;
}
private:
bool levelSupported(DispatchLevel level) const {
static const auto cpu_info = CpuInfo::getInstance();
switch (level) {
case DispatchLevel::NONE:
return true;
case DispatchLevel::AVX512:
case DispatchLevel::MAX:
return cpu_info->isSupported(CpuInfo::AVX512);
default:
return false;
}
}
};
} // namespace orc
#endif
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