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Re: [PATCH] Define std::atomic_ref and std::atomic<floating-point> for C++20
- From: Jonathan Wakely <jwakely at redhat dot com>
- To: libstdc++ at gcc dot gnu dot org, gcc-patches at gcc dot gnu dot org
- Date: Fri, 12 Jul 2019 12:49:06 +0100
- Subject: Re: [PATCH] Define std::atomic_ref and std::atomic<floating-point> for C++20
- References: <20190711194500.GA27493@redhat.com> <20190712112014.GJ4665@redhat.com>
On 12/07/19 12:20 +0100, Jonathan Wakely wrote:
On 11/07/19 20:45 +0100, Jonathan Wakely wrote:
This adds the new atomic types from C++2a, as proposed by P0019 and
P0020. To reduce duplication the calls to the compiler's atomic
built-ins are wrapped in new functions in the __atomic_impl namespace.
These functions are currently only used by std::atomic<floating-point>
and std::atomic_ref but could also be used for all other specializations
of std::atomic.
Here's a patch to reuse the new __atomic_impl functions in the
existing atomic<integral> and atomic<pointer> specializations (and
apply some general tidying up).
I don't plan to commit this yet, but I might do so at some point.
And here's a patch for https://wg21.link/lwg3220 which I won't apply
until that open issue is resolved.
commit 654cef2273b3231dd9ab64261183f477a378d795
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Fri Jul 12 12:46:42 2019 +0100
LWG 3220
diff --git a/libstdc++-v3/include/std/atomic b/libstdc++-v3/include/std/atomic
index 686ecc9114e..e1f1bbc488c 100644
--- a/libstdc++-v3/include/std/atomic
+++ b/libstdc++-v3/include/std/atomic
@@ -1183,13 +1183,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _ITp>
inline void
- atomic_store_explicit(atomic<_ITp>* __a, __atomic_val_t<_ITp> __i,
+ atomic_store_explicit(atomic<_ITp>* __a, __type_identity_t<_ITp> __i,
memory_order __m) noexcept
{ __a->store(__i, __m); }
template<typename _ITp>
inline void
- atomic_store_explicit(volatile atomic<_ITp>* __a, __atomic_val_t<_ITp> __i,
+ atomic_store_explicit(volatile atomic<_ITp>* __a,
+ __type_identity_t<_ITp> __i,
memory_order __m) noexcept
{ __a->store(__i, __m); }
@@ -1206,22 +1207,22 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _ITp>
inline _ITp
- atomic_exchange_explicit(atomic<_ITp>* __a, __atomic_val_t<_ITp> __i,
+ atomic_exchange_explicit(atomic<_ITp>* __a, __type_identity_t<_ITp> __i,
memory_order __m) noexcept
{ return __a->exchange(__i, __m); }
template<typename _ITp>
inline _ITp
atomic_exchange_explicit(volatile atomic<_ITp>* __a,
- __atomic_val_t<_ITp> __i,
+ __type_identity_t<_ITp> __i,
memory_order __m) noexcept
{ return __a->exchange(__i, __m); }
template<typename _ITp>
inline bool
atomic_compare_exchange_weak_explicit(atomic<_ITp>* __a,
- __atomic_val_t<_ITp>* __i1,
- __atomic_val_t<_ITp> __i2,
+ __type_identity_t<_ITp>* __i1,
+ __type_identity_t<_ITp> __i2,
memory_order __m1,
memory_order __m2) noexcept
{ return __a->compare_exchange_weak(*__i1, __i2, __m1, __m2); }
@@ -1229,8 +1230,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _ITp>
inline bool
atomic_compare_exchange_weak_explicit(volatile atomic<_ITp>* __a,
- __atomic_val_t<_ITp>* __i1,
- __atomic_val_t<_ITp> __i2,
+ __type_identity_t<_ITp>* __i1,
+ __type_identity_t<_ITp> __i2,
memory_order __m1,
memory_order __m2) noexcept
{ return __a->compare_exchange_weak(*__i1, __i2, __m1, __m2); }
@@ -1238,8 +1239,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _ITp>
inline bool
atomic_compare_exchange_strong_explicit(atomic<_ITp>* __a,
- __atomic_val_t<_ITp>* __i1,
- __atomic_val_t<_ITp> __i2,
+ __type_identity_t<_ITp>* __i1,
+ __type_identity_t<_ITp> __i2,
memory_order __m1,
memory_order __m2) noexcept
{ return __a->compare_exchange_strong(*__i1, __i2, __m1, __m2); }
@@ -1247,8 +1248,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _ITp>
inline bool
atomic_compare_exchange_strong_explicit(volatile atomic<_ITp>* __a,
- __atomic_val_t<_ITp>* __i1,
- __atomic_val_t<_ITp> __i2,
+ __type_identity_t<_ITp>* __i1,
+ __type_identity_t<_ITp> __i2,
memory_order __m1,
memory_order __m2) noexcept
{ return __a->compare_exchange_strong(*__i1, __i2, __m1, __m2); }
@@ -1256,12 +1257,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _ITp>
inline void
- atomic_store(atomic<_ITp>* __a, __atomic_val_t<_ITp> __i) noexcept
+ atomic_store(atomic<_ITp>* __a, __type_identity_t<_ITp> __i) noexcept
{ atomic_store_explicit(__a, __i, memory_order_seq_cst); }
template<typename _ITp>
inline void
- atomic_store(volatile atomic<_ITp>* __a, __atomic_val_t<_ITp> __i) noexcept
+ atomic_store(volatile atomic<_ITp>* __a,
+ __type_identity_t<_ITp> __i) noexcept
{ atomic_store_explicit(__a, __i, memory_order_seq_cst); }
template<typename _ITp>
@@ -1276,20 +1278,20 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _ITp>
inline _ITp
- atomic_exchange(atomic<_ITp>* __a, __atomic_val_t<_ITp> __i) noexcept
+ atomic_exchange(atomic<_ITp>* __a, __type_identity_t<_ITp> __i) noexcept
{ return atomic_exchange_explicit(__a, __i, memory_order_seq_cst); }
template<typename _ITp>
inline _ITp
atomic_exchange(volatile atomic<_ITp>* __a,
- __atomic_val_t<_ITp> __i) noexcept
+ __type_identity_t<_ITp> __i) noexcept
{ return atomic_exchange_explicit(__a, __i, memory_order_seq_cst); }
template<typename _ITp>
inline bool
atomic_compare_exchange_weak(atomic<_ITp>* __a,
- __atomic_val_t<_ITp>* __i1,
- __atomic_val_t<_ITp> __i2) noexcept
+ __type_identity_t<_ITp>* __i1,
+ __type_identity_t<_ITp> __i2) noexcept
{
return atomic_compare_exchange_weak_explicit(__a, __i1, __i2,
memory_order_seq_cst,
@@ -1299,8 +1301,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _ITp>
inline bool
atomic_compare_exchange_weak(volatile atomic<_ITp>* __a,
- __atomic_val_t<_ITp>* __i1,
- __atomic_val_t<_ITp> __i2) noexcept
+ __type_identity_t<_ITp>* __i1,
+ __type_identity_t<_ITp> __i2) noexcept
{
return atomic_compare_exchange_weak_explicit(__a, __i1, __i2,
memory_order_seq_cst,
@@ -1310,8 +1312,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _ITp>
inline bool
atomic_compare_exchange_strong(atomic<_ITp>* __a,
- __atomic_val_t<_ITp>* __i1,
- __atomic_val_t<_ITp> __i2) noexcept
+ __type_identity_t<_ITp>* __i1,
+ __type_identity_t<_ITp> __i2) noexcept
{
return atomic_compare_exchange_strong_explicit(__a, __i1, __i2,
memory_order_seq_cst,
@@ -1321,8 +1323,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _ITp>
inline bool
atomic_compare_exchange_strong(volatile atomic<_ITp>* __a,
- __atomic_val_t<_ITp>* __i1,
- __atomic_val_t<_ITp> __i2) noexcept
+ __type_identity_t<_ITp>* __i1,
+ __type_identity_t<_ITp> __i2) noexcept
{
return atomic_compare_exchange_strong_explicit(__a, __i1, __i2,
memory_order_seq_cst,