mirror of
https://github.com/matrix-construct/construct
synced 2024-11-18 16:00:57 +01:00
197 lines
4 KiB
C++
197 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_LZCNT_H
|
|
|
|
// This suite is for counting leading zero bits of a word T. It is not for
|
|
// per-lane clz'ing; for this reason all overloads are explicitly instantiated
|
|
// and optimal conversions are performed.
|
|
namespace ircd::simd
|
|
{
|
|
template<class T> uint _lzcnt(const T) noexcept;
|
|
template<class T> uint lzcnt(const T) noexcept = delete;
|
|
template<> uint lzcnt(const u512x1) noexcept;
|
|
template<> uint lzcnt(const u256x1) noexcept;
|
|
template<> uint lzcnt(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 can differ among
|
|
/// platforms; we make use of lzcnt if available otherwise we account for bsr.
|
|
template<class T>
|
|
[[gnu::always_inline]]
|
|
inline uint
|
|
ircd::simd::_lzcnt(const T a)
|
|
noexcept
|
|
{
|
|
uint ret(0);
|
|
for(uint i(0); i < lanes<T>(); ++i)
|
|
{
|
|
const auto mask
|
|
{
|
|
boolmask(uint(ret == sizeof_lane<T>() * 8 * i))
|
|
};
|
|
|
|
if constexpr(sizeof_lane<T>() <= sizeof(u8))
|
|
ret += mask & __builtin_clz((uint(a[i]) << 24) | 0x00ffffff);
|
|
|
|
else if constexpr(sizeof_lane<T>() <= sizeof(u16))
|
|
ret += mask & __builtin_clz((uint(__builtin_bswap16(a[i])) << 16) | 0x0000ffffU);
|
|
|
|
else if constexpr(sizeof_lane<T>() <= sizeof(u32))
|
|
ret += mask &
|
|
(
|
|
(boolmask(uint(a[i] != 0)) & __builtin_clz(__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_clzl(__builtin_bswap64(a[i])))
|
|
| (boolmask(uint(a[i] == 0)) & 64U)
|
|
);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::lzcnt(const u512x1 a)
|
|
noexcept
|
|
{
|
|
return _lzcnt(u64x8(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::lzcnt(const u256x1 a)
|
|
noexcept
|
|
{
|
|
return _lzcnt(u64x4(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::lzcnt(const u128x1 a)
|
|
noexcept
|
|
{
|
|
return _lzcnt(u64x2(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::lzcnt(const u64x8 a)
|
|
noexcept
|
|
{
|
|
return _lzcnt(u64x8(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::lzcnt(const u64x4 a)
|
|
noexcept
|
|
{
|
|
return _lzcnt(u64x4(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::lzcnt(const u64x2 a)
|
|
noexcept
|
|
{
|
|
return _lzcnt(u64x2(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::lzcnt(const u32x16 a)
|
|
noexcept
|
|
{
|
|
return _lzcnt(u64x8(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::lzcnt(const u32x8 a)
|
|
noexcept
|
|
{
|
|
return _lzcnt(u64x4(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::lzcnt(const u32x4 a)
|
|
noexcept
|
|
{
|
|
return _lzcnt(u64x2(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::lzcnt(const u16x32 a)
|
|
noexcept
|
|
{
|
|
return _lzcnt(u64x8(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::lzcnt(const u16x16 a)
|
|
noexcept
|
|
{
|
|
return _lzcnt(u64x4(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::lzcnt(const u16x8 a)
|
|
noexcept
|
|
{
|
|
return _lzcnt(u64x2(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::lzcnt(const u8x64 a)
|
|
noexcept
|
|
{
|
|
return _lzcnt(u64x8(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::lzcnt(const u8x32 a)
|
|
noexcept
|
|
{
|
|
return _lzcnt(u64x4(a));
|
|
}
|
|
|
|
template<>
|
|
inline uint
|
|
ircd::simd::lzcnt(const u8x16 a)
|
|
noexcept
|
|
{
|
|
return _lzcnt(u64x2(a));
|
|
}
|