{"id":2226283,"url":"http://patchwork.ozlabs.org/api/1.2/patches/2226283/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/patch/bmm.hhubrmqub2.gcc.gcc-TEST.redi.31.1.2@forge-stage.sourceware.org/","project":{"id":17,"url":"http://patchwork.ozlabs.org/api/1.2/projects/17/?format=json","name":"GNU Compiler Collection","link_name":"gcc","list_id":"gcc-patches.gcc.gnu.org","list_email":"gcc-patches@gcc.gnu.org","web_url":null,"scm_url":null,"webscm_url":null,"list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"","list_archive_url":null,"date":"2026-04-22T10:44:17","name":"[v1,02/16] libstdc++: Pass __wait_args to internal API by const pointer","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"d14834079a056e579a37011926cceea9f1c3dc0a","submitter":{"id":93210,"url":"http://patchwork.ozlabs.org/api/1.2/people/93210/?format=json","name":"Jonathan Wakely via Sourceware Forge","email":"forge-bot+redi@forge-stage.sourceware.org"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/gcc/patch/bmm.hhubrmqub2.gcc.gcc-TEST.redi.31.1.2@forge-stage.sourceware.org/mbox/","series":[{"id":500987,"url":"http://patchwork.ozlabs.org/api/1.2/series/500987/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/list/?series=500987","date":"2026-04-22T10:44:17","name":"atomic wait/notify ABI stabilization","version":1,"mbox":"http://patchwork.ozlabs.org/series/500987/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2226283/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2226283/checks/","tags":{},"related":[],"headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","gcc-patches@gcc.gnu.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","gcc-patches@gcc.gnu.org"],"Authentication-Results":["legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org\n 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[38.145.34.39])\n by sourceware.org (Postfix) with ESMTPS id BF4BC407C15D\n for ; Wed, 22 Apr 2026 10:46:01 +0000 (GMT)","from forge-stage.sourceware.org (localhost [IPv6:::1])\n (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n key-exchange x25519 server-signature ECDSA (prime256v1) server-digest SHA256)\n (No client certificate requested)\n by forge-stage.sourceware.org (Postfix) with ESMTPS id 9186D42BB0\n for ; Wed, 22 Apr 2026 10:46:01 +0000 (UTC)"],"DKIM-Filter":["OpenDKIM Filter v2.11.0 sourceware.org 0AEB44332694","OpenDKIM Filter v2.11.0 sourceware.org BF4BC407C15D"],"DMARC-Filter":"OpenDMARC Filter v1.4.2 sourceware.org BF4BC407C15D","ARC-Filter":"OpenARC Filter v1.0.0 sourceware.org BF4BC407C15D","ARC-Seal":"i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1776854761; cv=none;\n b=SXxU1hQkKDzVYZYxVvT7KZaY6L2kHlf3V13eOzFBn+O5hNt601vvE6JkrJItq6AWNuLuPF2T4XYrVzrGID8652g89L6qLkVUfWkJRvfJX/0pnVcfK/lTZcPyLw3D5Rb1egpNC0gV5im82yen7gStozbhe7fKVVYcyzvPnFOUhzM=","ARC-Message-Signature":"i=1; a=rsa-sha256; d=sourceware.org; s=key;\n t=1776854761; c=relaxed/simple;\n bh=tIu2bjh2S4Q3HiRqX1MZ7I1CnftSwo+0Vfu+fuovJCs=;\n h=From:Date:Subject:To:Message-ID;\n b=wJSke1hLPi7RrzSavR7iJAz0i4eNubUzcJr3uB1CZ453laCy5zCEgS6stZt8WRXSSNzXgjiEqg5wr2wrgKsREnEU5Uj71ABKN7DrqFtBMBC4Vwk4HBDL0ldpuqAJoln7b/iiP2YzvLyBbekUwITyg0EVgn5outLGkp/qwiQFmQ0=","ARC-Authentication-Results":"i=1; server2.sourceware.org","From":"Jonathan Wakely via Sourceware Forge\n ","Date":"Wed, 22 Apr 2026 10:44:17 +0000","Subject":"[PATCH v1 02/16] libstdc++: Pass __wait_args to internal API by const\n pointer","To":"gcc-patches mailing list ","Message-ID":"\n ","X-Mailer":"batrachomyomachia","X-Pull-Request-Organization":"gcc","X-Pull-Request-Repository":"gcc-TEST","X-Pull-Request":"https://forge.sourceware.org/gcc/gcc-TEST/pulls/31","References":"\n ","In-Reply-To":"\n ","X-Patch-URL":"\n https://forge.sourceware.org/redi/gcc/commit/28100ddd728733f8c5cd2f744c2d0dfd122254cc","X-BeenThere":"gcc-patches@gcc.gnu.org","X-Mailman-Version":"2.1.30","Precedence":"list","List-Id":"Gcc-patches mailing list ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Reply-To":"gcc-patches mailing list , redi@gcc.gnu.org","Errors-To":"gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org"},"content":"From: Thomas Rodgers \n\nThis change splits the __wait_args data members to a new struct\n__wait_args_base and then passes that type by const pointer to the low\nlevel implementation functions.\n\nlibstdc++-v3/ChangeLog:\n\n\t* include/bits/atomic_timed_wait.h (__spin_until_impl): Accept\n\t__wait_args as const __wait_args_base*.\n\t(__wait_until_impl): Likewise.\n\t(__wait_until): Likewise.\n\t(__wait_for): Likewise.\n\t(__atomic_wait_address_until): Pass __wait_args by address.\n\t(__atomic_wait_address_for): Likewise.\n\t* include/bits/atomic_wait.h (__wait_args_base): New struct.\n\t(__wait_args): Derive from __wait_args_base.\n\t(__wait_args::__wait_args()): Adjust ctors to call call base ctor.\n\t(__wait_args::__wait_args(const __wait_args_base&)): New ctor.\n\t(__wait_args::operator|=): New method.\n\t(__wait_args::_S_flags_for): Change return type to\n\t__wait_flags.\n\t(__spin_impl): Accept __wait_args as const __wait_args_base*.\n\t(__wait_impl): Likewise.\n\t(__notify_impl): Likewise.\n\t(__atomic_wait_address): Pass __wait_args by address.\n\t(__atomic_wait_address_v): Likewise.\n\t(__atomic_notify_address): Likewise.\n---\n libstdc++-v3/include/bits/atomic_timed_wait.h | 35 +++++++----\n libstdc++-v3/include/bits/atomic_wait.h | 62 +++++++++++++------\n 2 files changed, 64 insertions(+), 33 deletions(-)","diff":"diff --git a/libstdc++-v3/include/bits/atomic_timed_wait.h b/libstdc++-v3/include/bits/atomic_timed_wait.h\nindex 196548484024..4504b1b84bb8 100644\n--- a/libstdc++-v3/include/bits/atomic_timed_wait.h\n+++ b/libstdc++-v3/include/bits/atomic_timed_wait.h\n@@ -135,9 +135,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n #endif // _GLIBCXX_HAS_GTHREADS\n \n inline __wait_result_type\n- __spin_until_impl(const __platform_wait_t* __addr, __wait_args __args,\n+ __spin_until_impl(const __platform_wait_t* __addr,\n+\t\t const __wait_args_base* __a,\n \t\t const __wait_clock_t::time_point& __deadline)\n {\n+ __wait_args __args{ *__a };\n auto __t0 = __wait_clock_t::now();\n using namespace literals::chrono_literals;\n \n@@ -163,7 +165,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n \t}\n \telse\n \t{\n-\t auto __res = __detail::__spin_impl(__addr, __args);\n+\t auto __res = __detail::__spin_impl(__addr, __a);\n \t if (__res.first)\n \t return __res;\n \t}\n@@ -176,9 +178,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n }\n \n inline __wait_result_type\n- __wait_until_impl(const __platform_wait_t* __addr, __wait_args __args,\n+ __wait_until_impl(const __platform_wait_t* __addr,\n+\t\t const __wait_args_base* __a,\n \t\t const __wait_clock_t::time_point& __atime)\n {\n+ __wait_args __args{ *__a };\n #ifdef _GLIBCXX_HAVE_PLATFORM_TIMED_WAIT\n __waiter_pool_impl* __pool = nullptr;\n #else\n@@ -200,7 +204,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n \n if (__args & __wait_flags::__do_spin)\n \t{\n-\t auto __res = __detail::__spin_until_impl(__wait_addr, __args, __atime);\n+\t auto __res = __detail::__spin_until_impl(__wait_addr, __a, __atime);\n \t if (__res.first)\n \t return __res;\n \t if (__args & __wait_flags::__spin_only)\n@@ -246,7 +250,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n \n template\n __wait_result_type\n- __wait_until(const __platform_wait_t* __addr, __wait_args __args,\n+ __wait_until(const __platform_wait_t* __addr, const __wait_args* __args,\n \t\t const chrono::time_point<_Clock, _Dur>& __atime) noexcept\n {\n \tif constexpr (is_same_v<__wait_clock_t, _Clock>)\n@@ -269,15 +273,20 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n \n template\n __wait_result_type\n- __wait_for(const __platform_wait_t* __addr, __wait_args __args,\n+ __wait_for(const __platform_wait_t* __addr, const __wait_args_base* __a,\n \t\t const chrono::duration<_Rep, _Period>& __rtime) noexcept\n {\n+ __wait_args __args{ *__a };\n if (!__rtime.count())\n-\t// no rtime supplied, just spin a bit\n-\treturn __detail::__wait_impl(__addr, __args | __wait_flags::__spin_only);\n+\t{\n+\t // no rtime supplied, just spin a bit\n+\t __args |= __wait_flags::__spin_only;\n+\t return __detail::__wait_impl(__addr, &__args);\n+\t}\n+\n auto const __reltime = chrono::ceil<__wait_clock_t::duration>(__rtime);\n auto const __atime = chrono::steady_clock::now() + __reltime;\n- return __detail::__wait_until(__addr, __args, __atime);\n+ return __detail::__wait_until(__addr, &__args, __atime);\n }\n } // namespace __detail\n \n@@ -297,7 +306,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n _Tp __val = __vfn();\n while (!__pred(__val))\n \t {\n-\t auto __res = __detail::__wait_until(__wait_addr, __args, __atime);\n+\t auto __res = __detail::__wait_until(__wait_addr, &__args, __atime);\n \t if (!__res.first)\n \t // timed out\n \t return __res.first; // C++26 will also return last observed __val\n@@ -315,7 +324,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n \t\t\t\t bool __bare_wait = false) noexcept\n {\n __detail::__wait_args __args{ __addr, __old, __order, __bare_wait };\n- auto __res = __detail::__wait_until(__addr, __args, __atime);\n+ auto __res = __detail::__wait_until(__addr, &__args, __atime);\n return __res.first; // C++26 will also return last observed __val\n }\n \n@@ -347,7 +356,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n _Tp __val = __vfn();\n while (!__pred(__val))\n \t{\n-\t auto __res = __detail::__wait_for(__wait_addr, __args, __rtime);\n+\t auto __res = __detail::__wait_for(__wait_addr, &__args, __rtime);\n \t if (!__res.first)\n \t // timed out\n \t return __res.first; // C++26 will also return last observed __val\n@@ -365,7 +374,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n \t\t\t\tbool __bare_wait = false) noexcept\n {\n __detail::__wait_args __args{ __addr, __old, __order, __bare_wait };\n- auto __res = __detail::__wait_for(__addr, __args, __rtime);\n+ auto __res = __detail::__wait_for(__addr, &__args, __rtime);\n return __res.first; // C++26 will also return last observed __Val\n }\n \ndiff --git a/libstdc++-v3/include/bits/atomic_wait.h b/libstdc++-v3/include/bits/atomic_wait.h\nindex 18cfc2ef7bd2..cb246ed616d8 100644\n--- a/libstdc++-v3/include/bits/atomic_wait.h\n+++ b/libstdc++-v3/include/bits/atomic_wait.h\n@@ -215,23 +215,28 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n __abi_version_mask = 0xffff0000,\n };\n \n- struct __wait_args\n+ struct __wait_args_base\n {\n- __platform_wait_t _M_old;\n- int _M_order = __ATOMIC_ACQUIRE;\n __wait_flags _M_flags;\n+ int _M_order = __ATOMIC_ACQUIRE;\n+ __platform_wait_t _M_old = 0;\n+ };\n \n+ struct __wait_args : __wait_args_base\n+ {\n template\n \texplicit __wait_args(const _Tp* __addr,\n \t\t\t bool __bare_wait = false) noexcept\n-\t : _M_flags{ _S_flags_for(__addr, __bare_wait) }\n+\t : __wait_args_base{ _S_flags_for(__addr, __bare_wait) }\n \t{ }\n \n __wait_args(const __platform_wait_t* __addr, __platform_wait_t __old,\n \t\t int __order, bool __bare_wait = false) noexcept\n-\t : _M_old{ __old }\n-\t , _M_order{ __order }\n-\t , _M_flags{ _S_flags_for(__addr, __bare_wait) }\n+\t : __wait_args_base{ _S_flags_for(__addr, __bare_wait), __order, __old }\n+\t{ }\n+\n+ explicit __wait_args(const __wait_args_base& __base)\n+\t : __wait_args_base{ __base }\n \t{ }\n \n __wait_args(const __wait_args&) noexcept = default;\n@@ -257,6 +262,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n \treturn __res;\n }\n \n+ __wait_args&\n+ operator|=(__wait_flags __flag) noexcept\n+ {\n+\tusing __t = underlying_type_t<__wait_flags>;\n+\tconst auto __flags = static_cast<__t>(_M_flags)\n+\t\t\t | static_cast<__t>(__flag);\n+\t_M_flags = __wait_flags{ __flags };\n+\treturn *this;\n+ }\n+\n private:\n static int\n constexpr _S_default_flags() noexcept\n@@ -267,7 +282,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n }\n \n template\n-\tstatic int\n+\tstatic __wait_flags\n \tconstexpr _S_flags_for(const _Tp*, bool __bare_wait) noexcept\n \t{\n \t auto __res = _S_default_flags();\n@@ -275,7 +290,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n \t __res |= static_cast(__wait_flags::__track_contention);\n \t if constexpr (!__platform_wait_uses_type<_Tp>)\n \t __res |= static_cast(__wait_flags::__proxy_wait);\n-\t return __res;\n+\t return static_cast<__wait_flags>(__res);\n \t}\n \n template\n@@ -290,13 +305,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n \n using __wait_result_type = pair;\n inline __wait_result_type\n- __spin_impl(const __platform_wait_t* __addr, __wait_args __args)\n+ __spin_impl(const __platform_wait_t* __addr, const __wait_args_base* __args)\n {\n __platform_wait_t __val;\n for (auto __i = 0; __i < __atomic_spin_count; ++__i)\n \t{\n-\t __atomic_load(__addr, &__val, __args._M_order);\n-\t if (__val != __args._M_old)\n+\t __atomic_load(__addr, &__val, __args->_M_order);\n+\t if (__val != __args->_M_old)\n \t return make_pair(true, __val);\n \t if (__i < __atomic_spin_count_relax)\n \t __detail::__thread_relax();\n@@ -307,8 +322,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n }\n \n inline __wait_result_type\n- __wait_impl(const __platform_wait_t* __addr, __wait_args __args)\n+ __wait_impl(const __platform_wait_t* __addr, const __wait_args_base* __a)\n {\n+ __wait_args __args{ *__a };\n #ifdef _GLIBCXX_HAVE_PLATFORM_WAIT\n __waiter_pool_impl* __pool = nullptr;\n #else\n@@ -317,20 +333,25 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n #endif\n \n __platform_wait_t* __wait_addr;\n+ __platform_wait_t __old;\n if (__args & __wait_flags::__proxy_wait)\n \t{\n #ifdef _GLIBCXX_HAVE_PLATFORM_WAIT\n \t __pool = &__waiter_pool_impl::_S_impl_for(__addr);\n #endif\n \t __wait_addr = &__pool->_M_ver;\n-\t __atomic_load(__wait_addr, &__args._M_old, __args._M_order);\n+\t __atomic_load(__wait_addr, &__old, __args._M_order);\n \t}\n else\n-\t__wait_addr = const_cast<__platform_wait_t*>(__addr);\n+\t{\n+\t __wait_addr = const_cast<__platform_wait_t*>(__addr);\n+\t __old = __args._M_old;\n+\t}\n+\n \n if (__args & __wait_flags::__do_spin)\n \t{\n-\t auto __res = __detail::__spin_impl(__wait_addr, __args);\n+\t auto __res = __detail::__spin_impl(__wait_addr, __a);\n \t if (__res.first)\n \t return __res;\n \t if (__args & __wait_flags::__spin_only)\n@@ -372,8 +393,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n \n inline void\n __notify_impl(const __platform_wait_t* __addr, [[maybe_unused]] bool __all,\n-\t\t __wait_args __args)\n+\t\t const __wait_args_base* __a)\n {\n+ __wait_args __args{ __a };\n #ifdef _GLIBCXX_HAVE_PLATFORM_WAIT\n __waiter_pool_impl* __pool = nullptr;\n #else\n@@ -424,7 +446,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n _Tp __val = __vfn();\n while (!__pred(__val))\n \t{\n-\t __detail::__wait_impl(__wait_addr, __args);\n+\t __detail::__wait_impl(__wait_addr, &__args);\n \t __val = __vfn();\n \t}\n // C++26 will return __val\n@@ -437,7 +459,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n {\n __detail::__wait_args __args{ __addr, __old, __order };\n // C++26 will not ignore the return value here\n- __detail::__wait_impl(__addr, __args);\n+ __detail::__wait_impl(__addr, &__args);\n }\n \n template\n@@ -458,7 +480,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n const auto __wait_addr =\n \t reinterpret_cast(__addr);\n __detail::__wait_args __args{ __addr, __bare_wait };\n- __detail::__notify_impl(__wait_addr, __all, __args);\n+ __detail::__notify_impl(__wait_addr, __all, &__args);\n }\n _GLIBCXX_END_NAMESPACE_VERSION\n } // namespace std\n","prefixes":["v1","02/16"]}