mirror of
https://github.com/matrix-construct/construct
synced 2024-09-03 23:35:19 +02:00
150 lines
4.4 KiB
C++
150 lines
4.4 KiB
C++
// The Construct
|
|
//
|
|
// Copyright (C) The Construct Developers, Authors & Contributors
|
|
// Copyright (C) 2016-2020 Jason Volk <jason@zemos.net>
|
|
//
|
|
// Permission to use, copy, modify, and/or distribute this software for any
|
|
// purpose with or without fee is hereby granted, provided that the above
|
|
// copyright notice and this permission notice is present in all copies. The
|
|
// full license for this software is available in the LICENSE file.
|
|
|
|
#pragma once
|
|
#define HAVE_IRCD_BUFFER_STREAM_H
|
|
|
|
namespace ircd::buffer
|
|
{
|
|
size_t stream_aligned(const mutable_buffer &dst, const const_buffer &src);
|
|
}
|
|
|
|
/// Non-temporal copy. This copies from an aligned source to an aligned
|
|
/// destination without the data cycling through the d-cache. The alignment
|
|
/// requirements are currently very strict. The source and destination buffers
|
|
/// must begin at a cache-line alignment and the size of the buffers must be
|
|
/// a multiple of something we'll call "register-file size" which is the size
|
|
/// of all named multimedia registers (256 for SSE, 512 for AVX, 2048 for
|
|
/// AVX512) so it's safe to say buffers should just be aligned and padded out
|
|
/// to 4K page-size to be safe. The size of the src argument itself can be an
|
|
/// arbitrary size and this function will return that size, but its backing
|
|
/// buffer must be padded out to alignment.
|
|
///
|
|
inline size_t
|
|
ircd::buffer::stream_aligned(const mutable_buffer &dst,
|
|
const const_buffer &src)
|
|
{
|
|
// Platforms that have non-temporal store support; this is all of x86_64
|
|
constexpr bool has_store
|
|
{
|
|
#if defined(__SSE2__) && !defined(RB_GENERIC)
|
|
true
|
|
#else
|
|
false
|
|
#endif
|
|
};
|
|
|
|
// Platforms that have non-temporal load support; sidenote SSE4.1 can do
|
|
// 16 byte loads and AVX2 can do 32 byte loads; SSE2 cannot do loads.
|
|
constexpr bool has_load
|
|
{
|
|
#if defined(__AVX__) && !defined(RB_GENERIC)
|
|
true
|
|
#else
|
|
false
|
|
#endif
|
|
};
|
|
|
|
// Use the AVX512 vector type unconditionally as it conveniently matches
|
|
// the cache-line size on the relevant platforms and simplifies our syntax
|
|
// below by being a single object. On those w/o AVX512 it uses an
|
|
// isomorphic configuration of the best available regs.
|
|
using block_type = u512x1;
|
|
|
|
// The number of cache lines we'll have "in flight" which is basically
|
|
// just a gimmick to unroll the loop such that each iteration covers
|
|
// the full register file. On SSE with 256 bytes of register file we can
|
|
// name 4 cache lines at once; on AVX with 512 bytes we can name 8, etc.
|
|
constexpr size_t file_lines
|
|
{
|
|
#if defined(__AVX512F__)
|
|
32
|
|
#elif defined(__AVX__)
|
|
8
|
|
#else
|
|
4
|
|
#endif
|
|
};
|
|
|
|
// Configurable magic number only relevant to SSE2 systems which don't have
|
|
// non-temporal load instructions. On these platforms we'll conduct a
|
|
// prefetch loop and mark the lines NTA.
|
|
constexpr size_t latency
|
|
{
|
|
16
|
|
};
|
|
|
|
// When the constexpr conditions aren't favorable we can fallback to
|
|
// normal copy here.
|
|
if constexpr(!has_store && !has_load)
|
|
return copy(dst, src);
|
|
|
|
// Assert valid arguments
|
|
assert(!overlap(src, dst));
|
|
assert(aligned(data(src), sizeof(block_type)));
|
|
assert(aligned(data(dst), sizeof(block_type)));
|
|
assert(size(dst) % (sizeof(block_type) * file_lines));
|
|
|
|
// Size in bytes to be copied
|
|
const size_t copy_size
|
|
{
|
|
std::min(size(src), size(dst))
|
|
};
|
|
|
|
// Number of lines to be copied.
|
|
const size_t copy_lines
|
|
{
|
|
(copy_size / sizeof(block_type)) + bool(copy_size % sizeof(block_type))
|
|
};
|
|
|
|
// destination base ptr
|
|
block_type *const __restrict__ out
|
|
{
|
|
reinterpret_cast<block_type *__restrict__>(data(dst))
|
|
};
|
|
|
|
// source base ptr
|
|
const block_type *const __restrict__ in
|
|
{
|
|
reinterpret_cast<const block_type *__restrict__>(data(src))
|
|
};
|
|
|
|
if constexpr(!has_load)
|
|
#pragma clang loop unroll(disable)
|
|
for(size_t i(0); i < latency; ++i)
|
|
__builtin_prefetch(in + i, 0, 0);
|
|
|
|
for(size_t i(0); i < copy_lines; i += file_lines)
|
|
{
|
|
if constexpr(!has_load)
|
|
for(size_t j(0); j < file_lines; ++j)
|
|
__builtin_prefetch(in + i + latency + j, 0, 0);
|
|
|
|
block_type block[file_lines];
|
|
for(size_t j(0); j < file_lines; ++j)
|
|
#if defined(__clang__)
|
|
block[j] = __builtin_nontemporal_load(in + i + j);
|
|
#else
|
|
block[j] = *(in + i + j); //TODO: XXX
|
|
#endif
|
|
|
|
for(size_t j(0); j < file_lines; ++j)
|
|
#if defined(__clang__)
|
|
__builtin_nontemporal_store(block[j], out + i + j);
|
|
#else
|
|
*(out + i + j) = block[j]; //TODO: XXX
|
|
#endif
|
|
}
|
|
|
|
if constexpr(has_store)
|
|
asm volatile ("sfence");
|
|
|
|
return copy_size;
|
|
}
|