From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2181) id 1CAA33858D35; Thu, 12 Jan 2023 11:01:37 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 1CAA33858D35 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1673521297; bh=yFzt1mRbECGchgNdxEYgWJi7vyypxn4sYTOgQf70VoQ=; h=From:To:Subject:Date:From; b=Zd5zSK75KYvAoyq/DKzgNTDcKxl3Cv28M8LQyAz+YoTG3oUNOXd6U013fMo/wDhM8 uC8+N+tV0e8bHHbBRxK2/xtBqbQ0qNI0QoXhoRnVF2nF1pCHNTnG5paDZfDfyfkpSY nHrS4+2DCIbLoxsP9S+Gx34H8XF2CgPMsSj46x8Q= MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Jonathan Wakely To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r13-5119] libstdc++: Use lock-free type for __platform_wait_t X-Act-Checkin: gcc X-Git-Author: Jonathan Wakely X-Git-Refname: refs/heads/master X-Git-Oldrev: 2ce55247a8bf32985a96ed63a7a92d36746723dc X-Git-Newrev: dc22cf461278ace754042d9388a62afb002dfa0e Message-Id: <20230112110137.1CAA33858D35@sourceware.org> Date: Thu, 12 Jan 2023 11:01:37 +0000 (GMT) List-Id: https://gcc.gnu.org/g:dc22cf461278ace754042d9388a62afb002dfa0e commit r13-5119-gdc22cf461278ace754042d9388a62afb002dfa0e Author: Jonathan Wakely Date: Thu Jan 5 20:23:26 2023 +0000 libstdc++: Use lock-free type for __platform_wait_t For non-futex targets the __platform_wait_t type is currently uint64_t, but that requires a lock in libatomic for some 32-bit targets. We don't really need a 64-bit type, so use unsigned long if that is lock-free, and int otherwise. This should mean it's lock-free on a wider set of targets. libstdc++-v3/ChangeLog: * include/bits/atomic_wait.h (__detail::__platform_wait_t): Define as unsigned long if always lock-free, and unsigned int otherwise. Diff: --- libstdc++-v3/include/bits/atomic_wait.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/libstdc++-v3/include/bits/atomic_wait.h b/libstdc++-v3/include/bits/atomic_wait.h index bd1ed56d157..1d7a034a165 100644 --- a/libstdc++-v3/include/bits/atomic_wait.h +++ b/libstdc++-v3/include/bits/atomic_wait.h @@ -64,7 +64,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION // and __platform_notify() if there is a more efficient primitive supported // by the platform (e.g. __ulock_wait()/__ulock_wake()) which is better than // a mutex/condvar based wait. - using __platform_wait_t = uint64_t; +# if ATOMIC_LONG_LOCK_FREE == 2 + using __platform_wait_t = unsigned long; +# else + using __platform_wait_t = unsigned int; +# endif inline constexpr size_t __platform_wait_alignment = __alignof__(__platform_wait_t); #endif