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#pragma clang system_header
// 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.
#pragma once
#include <utility>
#include <vector>
#include "contrib/libs/apache/arrow_next/cpp/src/arrow/status.h"
#include "contrib/libs/apache/arrow_next/cpp/src/arrow/util/cpu_info.h"
namespace arrow20 {
namespace internal {
enum class DispatchLevel : int {
// These dispatch levels, corresponding to instruction set features,
// are sorted in increasing order of preference.
NONE = 0,
SSE4_2,
AVX2,
AVX512,
NEON,
MAX
};
/*
A facility for dynamic dispatch according to available DispatchLevel.
Typical use:
static void my_function_default(...);
static void my_function_avx2(...);
struct MyDynamicFunction {
using FunctionType = decltype(&my_function_default);
static std::vector<std::pair<DispatchLevel, FunctionType>> implementations() {
return {
{ DispatchLevel::NONE, my_function_default }
#if defined(ARROW_HAVE_RUNTIME_AVX2)
, { DispatchLevel::AVX2, my_function_avx2 }
#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 && IsSupported(impl.first)) {
// Higher (or same) level than current
cur = impl;
}
}
if (!cur.second) {
Status::Invalid("No appropriate implementation found").Abort();
}
func = cur.second;
}
private:
bool IsSupported(DispatchLevel level) const {
static const auto cpu_info = arrow20::internal::CpuInfo::GetInstance();
switch (level) {
case DispatchLevel::NONE:
return true;
case DispatchLevel::SSE4_2:
return cpu_info->IsSupported(CpuInfo::SSE4_2);
case DispatchLevel::AVX2:
return cpu_info->IsSupported(CpuInfo::AVX2);
case DispatchLevel::AVX512:
return cpu_info->IsSupported(CpuInfo::AVX512);
default:
return false;
}
}
};
} // namespace internal
} // namespace arrow20
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