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atomic: make use of gcc's __GCC_HAVE_SYNC_COMPARE_AND_SWAP_8

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__i686__ is not enabled for every platform supporting cmpxchg8b. to work
around this, we provide a separate implementation via gcc's atomic builtins

[SVN r81736]
This commit is contained in:
Tim Blechmann
2012-12-06 12:35:32 +00:00
parent 2eec3ea622
commit 3c288331b0
1 changed files with 10 additions and 2 deletions
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12
include/boost/atomic/detail/gcc-x86.hpp
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@@ -2,6 +2,7 @@
#define BOOST_ATOMIC_DETAIL_GCC_X86_HPP
// Copyright (c) 2009 Helge Bahmann
// Copyright (c) 2012 Tim Blechmann
//
// Distributed under the Boost Software License, Version 1.0.
// See accompanying file LICENSE_1_0.txt or copy at
@@ -1510,12 +1511,18 @@ private:
};
#endif
#if defined(__i686__) && !defined(__x86_64__)
#if !defined(__x86_64__) && (defined(__i686__) || defined (__GCC_HAVE_SYNC_COMPARE_AND_SWAP_8))
template<typename T>
bool
platform_cmpxchg64_strong(T & expected, T desired, volatile T * ptr)
{
#ifdef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_8
const T oldval = __sync_val_compare_and_swap(ptr, expected, desired);
const bool result = (oldval == expected);
expected = oldval;
return result;
#else
int scratch;
T prev = expected;
/* Make sure ebx is saved and restored properly in case
@@ -1543,6 +1550,7 @@ platform_cmpxchg64_strong(T & expected, T desired, volatile T * ptr)
bool success = (prev == expected);
expected = prev;
return success;
#endif
}
template<typename T>
@@ -1571,7 +1579,7 @@ platform_load64(const volatile T * ptr)
}
/* pull in 64-bit atomic type using cmpxchg8b above */
#if defined(__i686__) && !defined(__x86_64__)
#if !defined(__x86_64__) && (defined(__i686__) || defined (__GCC_HAVE_SYNC_COMPARE_AND_SWAP_8))
#include <boost/atomic/detail/cas64strong.hpp>
#endif