Date: Wed, 25 Jan 2023 01:44:56 GMT From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 4c4a29267cbd - main - libcxx: add comment explaining why umtx is only used for 64bits Message-ID: <202301250144.30P1iuok094205@gitrepo.freebsd.org>
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The branch main has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=4c4a29267cbdd05471322e03bfd5eff8eb68e750 commit 4c4a29267cbdd05471322e03bfd5eff8eb68e750 Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2023-01-24 15:36:24 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2023-01-25 01:19:42 +0000 libcxx: add comment explaining why umtx is only used for 64bits Requested by: imp Reviewed by: arichardson, emaste Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D38178 --- contrib/llvm-project/libcxx/src/atomic.cpp | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/contrib/llvm-project/libcxx/src/atomic.cpp b/contrib/llvm-project/libcxx/src/atomic.cpp index 4a2e466bd145..f90d28c2e569 100644 --- a/contrib/llvm-project/libcxx/src/atomic.cpp +++ b/contrib/llvm-project/libcxx/src/atomic.cpp @@ -78,6 +78,11 @@ static void __libcpp_platform_wake_by_address(__cxx_atomic_contention_t const vo } #elif defined(__FreeBSD__) && __SIZEOF_LONG__ == 8 +/* + * Since __cxx_contention_t is int64_t even on 32bit FreeBSD + * platforms, we have to use umtx ops that work on the long type, and + * limit its use to architectures where long and int64_t are synonyms. + */ static void __libcpp_platform_wait_on_address(__cxx_atomic_contention_t const volatile* __ptr, __cxx_contention_t __val)
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