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re PR libstdc++/65033 (C++11 atomics: is_lock_free result does not always match the real lock-free property)

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PR libstdc++/65033

 * include/bits/atomic_base.h (__atomic_base<T>::is_lock_free): Build
 a fake pointer indicating type alignment.
 (__atomic_base<T *>::is_lock_free): Likewise.
 * include/std/atomic (atomic<T>::is_lock_free): Likewise.

From-SVN: r221701
This commit is contained in:
Richard Henderson 2015-03-26 11:31:11 -07:00 committed by Richard Henderson
parent 41b38772cc
commit 8be568519b
3 changed files with 38 additions and 6 deletions
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8
libstdc++-v3/ChangeLog
View File

@ -1,3 +1,11 @@
2015-03-26 Richard Henderson <rth@redhat.com>
PR libstdc++/65033
* include/bits/atomic_base.h (__atomic_base<T>::is_lock_free): Build
a fake pointer indicating type alignment.
(__atomic_base<T *>::is_lock_free): Likewise.
* include/std/atomic (atomic<T>::is_lock_free): Likewise.
2015-03-25 Alan Lawrence <alan.lawrence@arm.com>
PR libstdc++/33394

24
libstdc++-v3/include/bits/atomic_base.h
View File

@ -346,11 +346,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
bool
is_lock_free() const noexcept
{ return __atomic_is_lock_free(sizeof(_M_i), nullptr); }
{
// Produce a fake, minimally aligned pointer.
void *__a = reinterpret_cast<void *>(-__alignof(_M_i));
return __atomic_is_lock_free(sizeof(_M_i), __a);
}
bool
is_lock_free() const volatile noexcept
{ return __atomic_is_lock_free(sizeof(_M_i), nullptr); }
{
// Produce a fake, minimally aligned pointer.
void *__a = reinterpret_cast<void *>(-__alignof(_M_i));
return __atomic_is_lock_free(sizeof(_M_i), __a);
}
_GLIBCXX_ALWAYS_INLINE void
store(__int_type __i, memory_order __m = memory_order_seq_cst) noexcept
@ -653,11 +661,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
bool
is_lock_free() const noexcept
{ return __atomic_is_lock_free(sizeof(__pointer_type), nullptr); }
{
// Produce a fake, minimally aligned pointer.
void *__a = reinterpret_cast<void *>(-__alignof(_M_p));
return __atomic_is_lock_free(sizeof(_M_p), __a);
}
bool
is_lock_free() const volatile noexcept
{ return __atomic_is_lock_free(sizeof(__pointer_type), nullptr); }
{
// Produce a fake, minimally aligned pointer.
void *__a = reinterpret_cast<void *>(-__alignof(_M_p));
return __atomic_is_lock_free(sizeof(_M_p), __a);
}
_GLIBCXX_ALWAYS_INLINE void
store(__pointer_type __p,

12
libstdc++-v3/include/std/atomic
View File

@ -198,11 +198,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
bool
is_lock_free() const noexcept
{ return __atomic_is_lock_free(sizeof(_M_i), nullptr); }
{
// Produce a fake, minimally aligned pointer.
void *__a = reinterpret_cast<void *>(-__alignof(_M_i));
return __atomic_is_lock_free(sizeof(_M_i), __a);
}
bool
is_lock_free() const volatile noexcept
{ return __atomic_is_lock_free(sizeof(_M_i), nullptr); }
{
// Produce a fake, minimally aligned pointer.
void *__a = reinterpret_cast<void *>(-__alignof(_M_i));
return __atomic_is_lock_free(sizeof(_M_i), __a);
}
void
store(_Tp __i, memory_order __m = memory_order_seq_cst) noexcept