skeleton-inl.h - mozsearch

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// Copyright 2020 Google LLC

// SPDX-License-Identifier: Apache-2.0

//

// 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.

// Demo of functions that might be called from multiple SIMD modules (either

// other -inl.h files, or a .cc file between begin/end_target-inl). This is

// optional - all SIMD code can reside in .cc files. However, this allows

// splitting code into different files while still inlining instead of requiring

// calling through function pointers.

// Per-target include guard. This is only required when using dynamic dispatch,

// i.e. including foreach_target.h. For static dispatch, a normal include

// guard would be fine because the header is only compiled once.

#if defined(HIGHWAY_HWY_EXAMPLES_SKELETON_INL_H_) == defined(HWY_TARGET_TOGGLE)

#ifdef HIGHWAY_HWY_EXAMPLES_SKELETON_INL_H_

#undef HIGHWAY_HWY_EXAMPLES_SKELETON_INL_H_

#else

#define HIGHWAY_HWY_EXAMPLES_SKELETON_INL_H_

#endif

// It is fine to #include normal or *-inl headers.

#include "hwy/highway.h"

HWY_BEFORE_NAMESPACE();

namespace skeleton {

namespace HWY_NAMESPACE {

// Highway ops reside here; ADL does not find templates nor builtins.

namespace hn = hwy::HWY_NAMESPACE;

// Example of a type-agnostic (caller-specified lane type) and width-agnostic

// (uses best available instruction set) function in a header.

//

// Computes x[i] = mul_array[i] * x_array[i] + add_array[i] for i < size.

template <class D, typename T>

HWY_MAYBE_UNUSED void MulAddLoop(const D d, const T* HWY_RESTRICT mul_array,

                                 const T* HWY_RESTRICT add_array,

                                 const size_t size, T* HWY_RESTRICT x_array) {

  for (size_t i = 0; i < size; i += hn::Lanes(d)) {

    const auto mul = hn::Load(d, mul_array + i);

    const auto add = hn::Load(d, add_array + i);

    auto x = hn::Load(d, x_array + i);

    x = hn::MulAdd(mul, x, add);

    hn::Store(x, d, x_array + i);

// NOLINTNEXTLINE(google-readability-namespace-comments)

}  // namespace HWY_NAMESPACE

}  // namespace skeleton

HWY_AFTER_NAMESPACE();

#endif  // include guard