Date: Sat, 20 Jun 2026 13:55:20 +0300 From: Konstantin Belousov <kib@freebsd.org> To: Warner Losh <imp@freebsd.org>, alc@freebsd.org Cc: src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org, Faraz Vahedi <kfv@kfv.io> Subject: Re: git: 9d87c1aac4a8 - main - libc: Add missing kill_dependency macro Message-ID: <ajZxmJoxyjjx0TSO@kib.kiev.ua> In-Reply-To: <6a35ddd4.24ba1.2ad9343d@gitrepo.freebsd.org>
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On Sat, Jun 20, 2026 at 12:24:52AM +0000, Warner Losh wrote: > The branch main has been updated by imp: > > URL: https://cgit.FreeBSD.org/src/commit/?id=9d87c1aac4a84ac5e82acf872f645a7202977204 > > commit 9d87c1aac4a84ac5e82acf872f645a7202977204 > Author: Faraz Vahedi <kfv@kfv.io> > AuthorDate: 2026-05-01 15:41:49 +0000 > Commit: Warner Losh <imp@FreeBSD.org> > CommitDate: 2026-06-20 00:23:28 +0000 > > libc: Add missing kill_dependency macro > > Add `kill_dependency` as specified by C11 ยง7.17.3.1. > > The macro is required to break dependency chains in > expressions without affecting the value. > > No functional impact beyond providing the required, > value-preserving definition. > > Signed-off-by: Faraz Vahedi <kfv@kfv.io> > Reviewed by: imp > Pull Request: https://github.com/freebsd/freebsd-src/pull/2185 > --- > sys/sys/stdatomic.h | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/sys/sys/stdatomic.h b/sys/sys/stdatomic.h > index 2d565ce991be..e6eb46cd6ef3 100644 > --- a/sys/sys/stdatomic.h > +++ b/sys/sys/stdatomic.h > @@ -141,6 +141,8 @@ typedef enum { > memory_order_seq_cst = __ATOMIC_SEQ_CST > } memory_order; > > +#define kill_dependency(y) (y) > + GCC at least with the version 16 uses a different definition for the kill_dependency(), which might have some side effects for the gcc optimizers: #define kill_dependency(Y) \ __extension__ \ ({ \ __auto_type __kill_dependency_tmp = (Y); \ __kill_dependency_tmp; \ }) Since the semantic for kill_dependency() is believed to be not well defined, I think we should provide gcc-compliant definition at least for gcc.home | help
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