From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9AE5E15B1 for ; Wed, 24 Jan 2024 14:58:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706108307; cv=none; b=n5GVNptNOpReA2XuBUSaYMMhhNudOODnFcQENzdgbxdKpvuL35GofJPRot4GXzSoihJ39FKQ/neWC6qGuN3DJDZIRz9hUU52ESE/YT+ntuA+cOHFz9sbpn54aeUHLmSreNvCQDOJ95sPkmjsHzDsHJj2jn4aC5/a4YQm+nrgXgA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706108307; c=relaxed/simple; bh=bha5nWQongh8wKqAdJp5MdVgFc0tjqxOq3t+tWQQ+30=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=aloQV2qfXjn3hL5Ab0sIYe3/9xGIj+utDYhnMiXNa3n7Vzi1A+/KN3qaOLGp+9o9IcESXvFOEGxmzvhwuSKh8JRygUR8Ldx2Xpe5pPVbD+dyRqISiH9uGhYsB8I6DDl6Aas4HwNXhxnHPz38UUGbSXb8/0Q87e9kwGtTgfLzjOo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FUYgc1sV; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="FUYgc1sV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 255C3C433F1; Wed, 24 Jan 2024 14:58:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706108307; bh=bha5nWQongh8wKqAdJp5MdVgFc0tjqxOq3t+tWQQ+30=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=FUYgc1sV/B5sYzVOU62cw2idC8jnwjHYEVhMI7N/2foWzZ7QP56qc/yxSelnaNESD GtahfUgkwP0SvqkUaKvx2UU+UnoVGPyYxqxY9HOGlF88C9yluWiR8LBW/2U3pG7bSV VXFExNFCT/3ovlMn9Bu5F04MPnPyslVIpI0cc0+iNGXWqchua40SB+T7fOVM5tQSjg jC5i0akKcRxCLQ5Zgkybd/tKyxH+jbaq3IjINiNPBvS1JAbwkE17VqfVIP5Z1QpLs5 tVYCvawHFrXu8jeHfzw32sZt+Alds6/ozf9ZaTSScMj7VyuUJJ4AqR+0PRpCCTr2DA WsY/Njtc99gVQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id BEECFCE0E8B; Wed, 24 Jan 2024 06:58:26 -0800 (PST) Date: Wed, 24 Jan 2024 06:58:26 -0800 From: "Paul E. McKenney" To: Linus Torvalds Cc: "H. Peter Anvin" , linux-toolchains@vger.kernel.org, peterz@infradead.org, rostedt@goodmis.org, gregkh@linuxfoundation.org, keescook@chromium.org Subject: Re: A few proposals from the C standards committee Message-ID: <99fac1e2-856d-4e05-abc5-e756b9cc3827@paulmck-laptop> Reply-To: paulmck@kernel.org References: <9162660e-2d6b-47a3-bfa2-77bfc55c817b@paulmck-laptop> <57324f9b-c851-4120-82b6-dbbf21cb2720@zytor.com> Precedence: bulk X-Mailing-List: linux-toolchains@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Jan 23, 2024 at 12:24:44PM -0800, Linus Torvalds wrote: > On Tue, 23 Jan 2024 at 12:19, H. Peter Anvin wrote: > > > > > n3203 Strict order of expression evaluation > > > I do like it. The 1980s were over a long time ago. > > > > The question is: is this going to wreck havoc with performance. The C++ > > reference implies it won't, though. > > Well, they also had numbers from an actual implementation showing that > it didn't (ie "win some, lose some"). > > The "ordering is undefined" is, I think, almost entirely an effect of > "compilers weren't that smart, and implementations differed". > > So I'd love for sequence points to go away. They are one of the more > subtle parts of C, and I do not believe that they have any real > advantage any more. > > (And by "go away" I obviously mean "everything is a sequence point", > not "nothing is a sequence point" - so they'd go away as a concept, > because they'd become a non-issue). Agreed, and here is hoping! Thanx, Paul