mirror of
https://github.com/matrix-construct/construct
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65 lines
1.8 KiB
C++
65 lines
1.8 KiB
C++
// The Construct
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//
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// Copyright (C) The Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2020 Jason Volk <jason@zemos.net>
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice is present in all copies. The
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// full license for this software is available in the LICENSE file.
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#pragma once
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#define HAVE_IRCD_SIMD_GATHER_H
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namespace ircd::simd
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{
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template<int scale = 1,
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class value,
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class index_vector,
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class value_vector>
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value_vector gather(const value *, const index_vector, const u64, value_vector) noexcept;
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}
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/// Gather values from memory locations into the returned vector. This template
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/// emits vpgather on skylake and later. On broadwell and haswell and earlier
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/// this template will not emit any vpgather by default.
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///
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/// Each lane in the index vector corresponds to each lane in the return vector.
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/// Each bit in the mask corresponds to each lane as well.
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/// The default values for each lane are provided in the last argument.
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///
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template<int scale,
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class value,
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class index_vector,
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class value_vector>
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inline value_vector
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ircd::simd::gather(const value *const __restrict__ base,
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const index_vector index,
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const u64 mask,
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value_vector ret)
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noexcept
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{
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static_assert
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(
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lanes<index_vector>() == lanes<value_vector>()
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);
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auto *const out
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{
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reinterpret_cast<lane_type<value_vector> *>(&ret)
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};
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const auto *const idx
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{
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reinterpret_cast<const lane_type<index_vector> *>(&index)
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};
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#if defined(__AVX2__)
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#pragma clang loop unroll(disable)
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#endif
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for(size_t i(0); i < lanes<index_vector>(); ++i)
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if(mask & (1UL << i))
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out[i] = base[idx[i] * scale];
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return ret;
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}
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