townforge/atomic
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Unified implementation of bitwise_fp_cast and bitwise_cast.

Browse Source 
Also use memset to clear the tail padding of the storage as gcc generates
slightly better code for that.
This commit is contained in:
Andrey Semashev 2018-02-14 02:36:11 +03:00
parent 72309f41f9
commit 92248dd5b8
3 changed files with 42 additions and 48 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

52
include/boost/atomic/detail/bitwise_cast.hpp
View File

@ -5,7 +5,7 @@
*
* Copyright (c) 2009 Helge Bahmann
* Copyright (c) 2012 Tim Blechmann
* Copyright (c) 2013 - 2014 Andrey Semashev
* Copyright (c) 2013 - 2018 Andrey Semashev
*/
/*!
* \file atomic/detail/bitwise_cast.hpp
@ -16,47 +16,53 @@
#ifndef BOOST_ATOMIC_DETAIL_BITWISE_CAST_HPP_INCLUDED_
#define BOOST_ATOMIC_DETAIL_BITWISE_CAST_HPP_INCLUDED_
#include <cstddef>
#include <boost/atomic/detail/config.hpp>
#include <boost/atomic/detail/addressof.hpp>
#include <boost/atomic/detail/string_ops.hpp>
#include <boost/atomic/detail/type_traits/integral_constant.hpp>
#ifdef BOOST_HAS_PRAGMA_ONCE
#pragma once
#endif
#if defined(BOOST_GCC) && (BOOST_GCC+0) >= 40600
#pragma GCC diagnostic push
// missing initializer for member var
#pragma GCC diagnostic ignored "-Wmissing-field-initializers"
#endif
namespace boost {
namespace atomics {
namespace detail {
template< std::size_t FromSize, typename To >
BOOST_FORCEINLINE void clear_padding(To& to, atomics::detail::true_type) BOOST_NOEXCEPT
{
BOOST_ATOMIC_DETAIL_MEMSET(reinterpret_cast< unsigned char* >(atomics::detail::addressof(to)) + FromSize, 0, sizeof(To) - FromSize);
}
template< std::size_t FromSize, typename To >
BOOST_FORCEINLINE void clear_padding(To& to, atomics::detail::false_type) BOOST_NOEXCEPT
{
}
template< typename To, std::size_t FromSize, typename From >
BOOST_FORCEINLINE To bitwise_cast(From const& from) BOOST_NOEXCEPT
{
To to;
BOOST_ATOMIC_DETAIL_MEMCPY
(
atomics::detail::addressof(to),
atomics::detail::addressof(from),
(FromSize < sizeof(To) ? FromSize : sizeof(To))
);
atomics::detail::clear_padding< FromSize >(to, atomics::detail::integral_constant< bool, FromSize < sizeof(To) >());
return to;
}
template< typename To, typename From >
BOOST_FORCEINLINE To bitwise_cast(From const& from) BOOST_NOEXCEPT
{
struct
{
To to;
}
value = {};
BOOST_ATOMIC_DETAIL_MEMCPY
(
atomics::detail::addressof(value.to),
atomics::detail::addressof(from),
(sizeof(From) < sizeof(To) ? sizeof(From) : sizeof(To))
);
return value.to;
return atomics::detail::bitwise_cast< To, sizeof(From) >(from);
}
} // namespace detail
} // namespace atomics
} // namespace boost
#if defined(BOOST_GCC) && (BOOST_GCC+0) >= 40600
#pragma GCC diagnostic pop
#endif
#endif // BOOST_ATOMIC_DETAIL_BITWISE_CAST_HPP_INCLUDED_

26
include/boost/atomic/detail/bitwise_fp_cast.hpp
View File

@ -16,20 +16,13 @@
#include <cstddef>
#include <boost/atomic/detail/config.hpp>
#include <boost/atomic/detail/addressof.hpp>
#include <boost/atomic/detail/string_ops.hpp>
#include <boost/atomic/detail/float_sizes.hpp>
#include <boost/atomic/detail/bitwise_cast.hpp>
#ifdef BOOST_HAS_PRAGMA_ONCE
#pragma once
#endif
#if defined(BOOST_GCC) && (BOOST_GCC+0) >= 40600
#pragma GCC diagnostic push
// missing initializer for member var
#pragma GCC diagnostic ignored "-Wmissing-field-initializers"
#endif
namespace boost {
namespace atomics {
namespace detail {
@ -83,26 +76,11 @@ struct value_sizeof< const volatile T > : value_sizeof< T > {};
template< typename To, typename From >
BOOST_FORCEINLINE To bitwise_fp_cast(From const& from) BOOST_NOEXCEPT
{
struct
{
To to;
}
value = {};
BOOST_ATOMIC_DETAIL_MEMCPY
(
atomics::detail::addressof(value.to),
atomics::detail::addressof(from),
(atomics::detail::value_sizeof< From >::value < sizeof(To) ? atomics::detail::value_sizeof< From >::value : sizeof(To))
);
return value.to;
return atomics::detail::bitwise_cast< To, atomics::detail::value_sizeof< From >::value >(from);
}
} // namespace detail
} // namespace atomics
} // namespace boost
#if defined(BOOST_GCC) && (BOOST_GCC+0) >= 40600
#pragma GCC diagnostic pop
#endif
#endif // BOOST_ATOMIC_DETAIL_BITWISE_FP_CAST_HPP_INCLUDED_

12
include/boost/atomic/detail/string_ops.hpp
View File

@ -27,9 +27,13 @@
#if __has_builtin(__builtin_memcmp)
#define BOOST_ATOMIC_DETAIL_HAS_BUILTIN_MEMCMP
#endif
#if __has_builtin(__builtin_memset)
#define BOOST_ATOMIC_DETAIL_HAS_BUILTIN_MEMSET
#endif
#elif defined(BOOST_GCC)
#define BOOST_ATOMIC_DETAIL_HAS_BUILTIN_MEMCPY
#define BOOST_ATOMIC_DETAIL_HAS_BUILTIN_MEMCMP
#define BOOST_ATOMIC_DETAIL_HAS_BUILTIN_MEMSET
#endif
#if defined(BOOST_ATOMIC_DETAIL_HAS_BUILTIN_MEMCPY)
@ -44,7 +48,13 @@
#define BOOST_ATOMIC_DETAIL_MEMCMP std::memcmp
#endif
#if !defined(BOOST_ATOMIC_DETAIL_HAS_BUILTIN_MEMCPY) || !defined(BOOST_ATOMIC_DETAIL_HAS_BUILTIN_MEMCMP)
#if defined(BOOST_ATOMIC_DETAIL_HAS_BUILTIN_MEMSET)
#define BOOST_ATOMIC_DETAIL_MEMSET __builtin_memset
#else
#define BOOST_ATOMIC_DETAIL_MEMSET std::memset
#endif
#if !defined(BOOST_ATOMIC_DETAIL_HAS_BUILTIN_MEMCPY) || !defined(BOOST_ATOMIC_DETAIL_HAS_BUILTIN_MEMCMP) || !defined(BOOST_ATOMIC_DETAIL_HAS_BUILTIN_MEMSET)
#include <cstring>
#endif