mirror of
https://github.com/matrix-construct/construct
synced 2024-11-18 07:50:57 +01:00
195 lines
4 KiB
C++
195 lines
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_SIMD_TZCNT_H
|
|
|
|
// This suite is for counting trailing zero bits of a word T. It is not for
|
|
// per-lane ctz'ing; for this reason all overloads are explicitly instantiated
|
|
// and optimal conversions are performed.
|
|
namespace ircd::simd
|
|
{
|
|
template<class T> uint _tzcnt(const T) noexcept;
|
|
template<class T> uint tzcnt(const T) noexcept = delete;
|
|
template<> uint tzcnt(const u512x1) noexcept;
|
|
template<> uint tzcnt(const u256x1) noexcept;
|
|
template<> uint tzcnt(const u128x1) noexcept;
|
|
template<> uint lzcnt(const u64x8) noexcept;
|
|
template<> uint lzcnt(const u64x4) noexcept;
|
|
template<> uint lzcnt(const u64x2) noexcept;
|
|
template<> uint lzcnt(const u32x16) noexcept;
|
|
template<> uint lzcnt(const u32x8) noexcept;
|
|
template<> uint lzcnt(const u32x4) noexcept;
|
|
template<> uint lzcnt(const u16x32) noexcept;
|
|
template<> uint lzcnt(const u16x16) noexcept;
|
|
template<> uint lzcnt(const u16x8) noexcept;
|
|
template<> uint lzcnt(const u8x64) noexcept;
|
|
template<> uint lzcnt(const u8x32) noexcept;
|
|
template<> uint lzcnt(const u8x16) noexcept;
|
|
}
|
|
|
|
/// Convenience template. Unfortunately this drops to scalar until specific
|
|
/// targets and specializations are created. The behavior of can differ among
|
|
/// platforms; we use lzcnt when available, otherwise we account for bsr.
|
|
template<class T>
|
|
[[gnu::always_inline]]
|
|
inline uint
|
|
ircd::simd::_tzcnt(const T a)
|
|
noexcept
|
|
{
|
|
uint ret(0), i(lanes<T>() - 1), mask(-1U); do
|
|
{
|
|
if constexpr(sizeof_lane<T>() <= sizeof(u8))
|
|
ret += mask & __builtin_ctz(a[i] | 0xffffff00U);
|
|
|
|
else if constexpr(sizeof_lane<T>() <= sizeof(u16))
|
|
ret += mask & __builtin_ctz(__builtin_bswap16(a[i]) | 0xffff0000U);
|
|
|
|
else if constexpr(sizeof_lane<T>() <= sizeof(u32))
|
|
ret += mask &
|
|
(
|
|
(boolmask(uint(a[i] != 0)) & __builtin_ctz(__builtin_bswap32(a[i])))
|
|
| (boolmask(uint(a[i] == 0)) & 32U)
|
|
);
|
|
|
|
else if constexpr(sizeof_lane<T>() <= sizeof(u64))
|
|
ret += mask &
|
|
(
|
|
(boolmask(uint(a[i] != 0)) & __builtin_ctzl(__builtin_bswap64(a[i])))
|
|
| (boolmask(uint(a[i] == 0)) & 64U)
|
|
);
|
|
|
|
static const auto lane_bits(sizeof_lane<T>() * 8);
|
|
mask &= boolmask(uint(ret % lane_bits == 0));
|
|
mask &= boolmask(uint(ret != 0));
|
|
}
|
|
while(i--);
|
|
return ret;
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::tzcnt(const u512x1 a)
|
|
noexcept
|
|
{
|
|
return _tzcnt(u64x8(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::tzcnt(const u256x1 a)
|
|
noexcept
|
|
{
|
|
return _tzcnt(u64x4(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::tzcnt(const u128x1 a)
|
|
noexcept
|
|
{
|
|
return _tzcnt(u64x2(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::tzcnt(const u64x8 a)
|
|
noexcept
|
|
{
|
|
return _tzcnt(u64x8(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::tzcnt(const u64x4 a)
|
|
noexcept
|
|
{
|
|
return _tzcnt(u64x4(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::tzcnt(const u64x2 a)
|
|
noexcept
|
|
{
|
|
return _tzcnt(u64x2(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::tzcnt(const u32x16 a)
|
|
noexcept
|
|
{
|
|
return _tzcnt(u64x8(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::tzcnt(const u32x8 a)
|
|
noexcept
|
|
{
|
|
return _tzcnt(u64x4(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::tzcnt(const u32x4 a)
|
|
noexcept
|
|
{
|
|
return _tzcnt(u64x2(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::tzcnt(const u16x32 a)
|
|
noexcept
|
|
{
|
|
return _tzcnt(u64x8(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::tzcnt(const u16x16 a)
|
|
noexcept
|
|
{
|
|
return _tzcnt(u64x4(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::tzcnt(const u16x8 a)
|
|
noexcept
|
|
{
|
|
return _tzcnt(u64x2(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::tzcnt(const u8x64 a)
|
|
noexcept
|
|
{
|
|
return _tzcnt(u64x8(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::tzcnt(const u8x32 a)
|
|
noexcept
|
|
{
|
|
return _tzcnt(u64x4(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::tzcnt(const u8x16 a)
|
|
noexcept
|
|
{
|
|
return _tzcnt(u64x2(a));
|
|
}
|