From: Jonathan Wakely <jwakely@redhat.com>
To: libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org
Cc: Thomas Rodgers <rodgert@twrodgers.com>,
Thomas Rodgers <trodgers@redhat.com>
Subject: [PATCH 2/2] libstdc++: Pass __wait_args to internal API by const pointer
Date: Thu, 16 Nov 2023 13:45:38 +0000 [thread overview]
Message-ID: <20231116134736.1287539-2-jwakely@redhat.com> (raw)
In-Reply-To: <20231116134736.1287539-1-jwakely@redhat.com>
From: Thomas Rodgers <trodgers@redhat.com>
Tested x86_64-linux, testing underway on powerpc-aix and sparc-solaris.
-- >8 --
This change splits the __wait_args data members to a new struct
__wait_args_base and then passes that type by const pointer to the low
level implementation functions.
libstdc++-v3/ChangeLog:
* include/bits/atomic_timed_wait.h (__spin_until_impl): Accept
__wait_args as const __wait_args_base*.
(__wait_until_impl): Likewise.
(__wait_until): Likewise.
(__wait_for): Likewise.
(__atomic_wait_address_until): Pass __wait_args by address.
(__atomic_wait_address_for): Likewise.
* include/bits/atomic_wait.h (__wait_args_base): New struct.
(__wait_args): Derive from __wait_args_base.
(__wait_args::__wait_args()): Adjust ctors to call call base ctor.
(__wait_args::__wait_args(const __wait_args_base&)): New ctor.
(__wait_args::operator|=): New method.
(__wait_args::_S_flags_for): Change return type to
__wait_flags.
(__spin_impl): Accept __wait_args as const __wait_args_base*.
(__wait_impl): Likewise.
(__notify_impl): Likewise.
(__atomic_wait_address): Pass __wait_args by address.
(__atomic_wait_address_v): Likewise.
(__atomic_notify_address): Likewise.
---
libstdc++-v3/include/bits/atomic_timed_wait.h | 35 +++++++----
libstdc++-v3/include/bits/atomic_wait.h | 62 +++++++++++++------
2 files changed, 64 insertions(+), 33 deletions(-)
diff --git a/libstdc++-v3/include/bits/atomic_timed_wait.h b/libstdc++-v3/include/bits/atomic_timed_wait.h
index 90427ef8b42..6f6e8758ee2 100644
--- a/libstdc++-v3/include/bits/atomic_timed_wait.h
+++ b/libstdc++-v3/include/bits/atomic_timed_wait.h
@@ -133,9 +133,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#endif // _GLIBCXX_HAS_GTHREADS
inline __wait_result_type
- __spin_until_impl(const __platform_wait_t* __addr, __wait_args __args,
+ __spin_until_impl(const __platform_wait_t* __addr,
+ const __wait_args_base* __a,
const __wait_clock_t::time_point& __deadline)
{
+ __wait_args __args{ *__a };
auto __t0 = __wait_clock_t::now();
using namespace literals::chrono_literals;
@@ -161,7 +163,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
else
{
- auto __res = __detail::__spin_impl(__addr, __args);
+ auto __res = __detail::__spin_impl(__addr, __a);
if (__res.first)
return __res;
}
@@ -174,9 +176,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
inline __wait_result_type
- __wait_until_impl(const __platform_wait_t* __addr, __wait_args __args,
+ __wait_until_impl(const __platform_wait_t* __addr,
+ const __wait_args_base* __a,
const __wait_clock_t::time_point& __atime)
{
+ __wait_args __args{ *__a };
#ifdef _GLIBCXX_HAVE_PLATFORM_TIMED_WAIT
__waiter_pool_impl* __pool = nullptr;
#else
@@ -198,7 +202,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
if (__args & __wait_flags::__do_spin)
{
- auto __res = __detail::__spin_until_impl(__wait_addr, __args, __atime);
+ auto __res = __detail::__spin_until_impl(__wait_addr, __a, __atime);
if (__res.first)
return __res;
if (__args & __wait_flags::__spin_only)
@@ -244,7 +248,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Clock, typename _Dur>
__wait_result_type
- __wait_until(const __platform_wait_t* __addr, __wait_args __args,
+ __wait_until(const __platform_wait_t* __addr, const __wait_args* __args,
const chrono::time_point<_Clock, _Dur>& __atime) noexcept
{
if constexpr (is_same_v<__wait_clock_t, _Clock>)
@@ -267,15 +271,20 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Rep, typename _Period>
__wait_result_type
- __wait_for(const __platform_wait_t* __addr, __wait_args __args,
+ __wait_for(const __platform_wait_t* __addr, const __wait_args_base* __a,
const chrono::duration<_Rep, _Period>& __rtime) noexcept
{
+ __wait_args __args{ *__a };
if (!__rtime.count())
- // no rtime supplied, just spin a bit
- return __detail::__wait_impl(__addr, __args | __wait_flags::__spin_only);
+ {
+ // no rtime supplied, just spin a bit
+ __args |= __wait_flags::__spin_only;
+ return __detail::__wait_impl(__addr, &__args);
+ }
+
auto const __reltime = chrono::ceil<__wait_clock_t::duration>(__rtime);
auto const __atime = chrono::steady_clock::now() + __reltime;
- return __detail::__wait_until(__addr, __args, __atime);
+ return __detail::__wait_until(__addr, &__args, __atime);
}
} // namespace __detail
@@ -295,7 +304,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_Tp __val = __vfn();
while (!__pred(__val))
{
- auto __res = __detail::__wait_until(__wait_addr, __args, __atime);
+ auto __res = __detail::__wait_until(__wait_addr, &__args, __atime);
if (!__res.first)
// timed out
return __res.first; // C++26 will also return last observed __val
@@ -313,7 +322,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
bool __bare_wait = false) noexcept
{
__detail::__wait_args __args{ __addr, __old, __order, __bare_wait };
- auto __res = __detail::__wait_until(__addr, __args, __atime);
+ auto __res = __detail::__wait_until(__addr, &__args, __atime);
return __res.first; // C++26 will also return last observed __val
}
@@ -345,7 +354,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_Tp __val = __vfn();
while (!__pred(__val))
{
- auto __res = __detail::__wait_for(__wait_addr, __args, __rtime);
+ auto __res = __detail::__wait_for(__wait_addr, &__args, __rtime);
if (!__res.first)
// timed out
return __res.first; // C++26 will also return last observed __val
@@ -363,7 +372,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
bool __bare_wait = false) noexcept
{
__detail::__wait_args __args{ __addr, __old, __order, __bare_wait };
- auto __res = __detail::__wait_for(__addr, __args, __rtime);
+ auto __res = __detail::__wait_for(__addr, &__args, __rtime);
return __res.first; // C++26 will also return last observed __Val
}
diff --git a/libstdc++-v3/include/bits/atomic_wait.h b/libstdc++-v3/include/bits/atomic_wait.h
index 63d132fc9a8..8abcdec3d50 100644
--- a/libstdc++-v3/include/bits/atomic_wait.h
+++ b/libstdc++-v3/include/bits/atomic_wait.h
@@ -212,23 +212,28 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__abi_version_mask = 0xffff0000,
};
- struct __wait_args
+ struct __wait_args_base
{
- __platform_wait_t _M_old;
- int _M_order = __ATOMIC_ACQUIRE;
__wait_flags _M_flags;
+ int _M_order = __ATOMIC_ACQUIRE;
+ __platform_wait_t _M_old = 0;
+ };
+ struct __wait_args : __wait_args_base
+ {
template<typename _Tp>
explicit __wait_args(const _Tp* __addr,
bool __bare_wait = false) noexcept
- : _M_flags{ _S_flags_for(__addr, __bare_wait) }
+ : __wait_args_base{ _S_flags_for(__addr, __bare_wait) }
{ }
__wait_args(const __platform_wait_t* __addr, __platform_wait_t __old,
int __order, bool __bare_wait = false) noexcept
- : _M_old{ __old }
- , _M_order{ __order }
- , _M_flags{ _S_flags_for(__addr, __bare_wait) }
+ : __wait_args_base{ _S_flags_for(__addr, __bare_wait), __order, __old }
+ { }
+
+ explicit __wait_args(const __wait_args_base& __base)
+ : __wait_args_base{ __base }
{ }
__wait_args(const __wait_args&) noexcept = default;
@@ -254,6 +259,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return __res;
}
+ __wait_args&
+ operator|=(__wait_flags __flag) noexcept
+ {
+ using __t = underlying_type_t<__wait_flags>;
+ const auto __flags = static_cast<__t>(_M_flags)
+ | static_cast<__t>(__flag);
+ _M_flags = __wait_flags{ __flags };
+ return *this;
+ }
+
private:
static int
constexpr _S_default_flags() noexcept
@@ -264,7 +279,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
template<typename _Tp>
- static int
+ static __wait_flags
constexpr _S_flags_for(const _Tp*, bool __bare_wait) noexcept
{
auto __res = _S_default_flags();
@@ -272,7 +287,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__res |= static_cast<int>(__wait_flags::__track_contention);
if constexpr (!__platform_wait_uses_type<_Tp>)
__res |= static_cast<int>(__wait_flags::__proxy_wait);
- return __res;
+ return static_cast<__wait_flags>(__res);
}
template<typename _Tp>
@@ -287,13 +302,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
using __wait_result_type = pair<bool, __platform_wait_t>;
inline __wait_result_type
- __spin_impl(const __platform_wait_t* __addr, __wait_args __args)
+ __spin_impl(const __platform_wait_t* __addr, const __wait_args_base* __args)
{
__platform_wait_t __val;
for (auto __i = 0; __i < __atomic_spin_count; ++__i)
{
- __atomic_load(__addr, &__val, __args._M_order);
- if (__val != __args._M_old)
+ __atomic_load(__addr, &__val, __args->_M_order);
+ if (__val != __args->_M_old)
return make_pair(true, __val);
if (__i < __atomic_spin_count_relax)
__detail::__thread_relax();
@@ -304,8 +319,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
inline __wait_result_type
- __wait_impl(const __platform_wait_t* __addr, __wait_args __args)
+ __wait_impl(const __platform_wait_t* __addr, const __wait_args_base* __a)
{
+ __wait_args __args{ *__a };
#ifdef _GLIBCXX_HAVE_PLATFORM_WAIT
__waiter_pool_impl* __pool = nullptr;
#else
@@ -314,20 +330,25 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#endif
__platform_wait_t* __wait_addr;
+ __platform_wait_t __old;
if (__args & __wait_flags::__proxy_wait)
{
#ifdef _GLIBCXX_HAVE_PLATFORM_WAIT
__pool = &__waiter_pool_impl::_S_impl_for(__addr);
#endif
__wait_addr = &__pool->_M_ver;
- __atomic_load(__wait_addr, &__args._M_old, __args._M_order);
+ __atomic_load(__wait_addr, &__old, __args._M_order);
}
else
- __wait_addr = const_cast<__platform_wait_t*>(__addr);
+ {
+ __wait_addr = const_cast<__platform_wait_t*>(__addr);
+ __old = __args._M_old;
+ }
+
if (__args & __wait_flags::__do_spin)
{
- auto __res = __detail::__spin_impl(__wait_addr, __args);
+ auto __res = __detail::__spin_impl(__wait_addr, __a);
if (__res.first)
return __res;
if (__args & __wait_flags::__spin_only)
@@ -369,8 +390,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
inline void
__notify_impl(const __platform_wait_t* __addr, [[maybe_unused]] bool __all,
- __wait_args __args)
+ const __wait_args_base* __a)
{
+ __wait_args __args{ __a };
#ifdef _GLIBCXX_HAVE_PLATFORM_WAIT
__waiter_pool_impl* __pool = nullptr;
#else
@@ -421,7 +443,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_Tp __val = __vfn();
while (!__pred(__val))
{
- __detail::__wait_impl(__wait_addr, __args);
+ __detail::__wait_impl(__wait_addr, &__args);
__val = __vfn();
}
// C++26 will return __val
@@ -434,7 +456,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
__detail::__wait_args __args{ __addr, __old, __order };
// C++26 will not ignore the return value here
- __detail::__wait_impl(__addr, __args);
+ __detail::__wait_impl(__addr, &__args);
}
template<typename _Tp, typename _ValFn>
@@ -455,7 +477,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
const auto __wait_addr =
reinterpret_cast<const __detail::__platform_wait_t*>(__addr);
__detail::__wait_args __args{ __addr, __bare_wait };
- __detail::__notify_impl(__wait_addr, __all, __args);
+ __detail::__notify_impl(__wait_addr, __all, &__args);
}
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
--
2.41.0
next prev parent reply other threads:[~2023-11-16 13:47 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-16 13:45 [PATCH 1/2] libstdc++: Atomic wait/notify ABI stabilization Jonathan Wakely
2023-11-16 13:45 ` Jonathan Wakely [this message]
2023-11-16 20:46 ` Jonathan Wakely
2024-03-09 12:18 ` Jonathan Wakely
2024-03-09 12:27 ` Jonathan Wakely
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