Date: Tue, 31 Jan 2023 00:39:08 GMT From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: c8d8e959b51a - stable/13 - libcxx: add comment explaining why umtx is only used for 64bits Message-ID: <202301310039.30V0d8Hl059549@gitrepo.freebsd.org>
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The branch stable/13 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=c8d8e959b51a47a623a0c46d5966009455912f04 commit c8d8e959b51a47a623a0c46d5966009455912f04 Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2023-01-24 15:36:24 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2023-01-31 00:38:18 +0000 libcxx: add comment explaining why umtx is only used for 64bits (cherry picked from commit 4c4a29267cbdd05471322e03bfd5eff8eb68e750) --- 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 6f85c86aad8f..7bd9205a963b 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 && !defined(__mips__) +/* + * 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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