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[209.85.208.46]) by smtp.gmail.com with ESMTPSA id n13-20020a05640204cd00b0055971af7a23sm10459494edw.95.2024.01.23.12.25.01 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 23 Jan 2024 12:25:01 -0800 (PST) Received: by mail-ed1-f46.google.com with SMTP id 4fb4d7f45d1cf-55a86795a3bso4553352a12.1 for ; Tue, 23 Jan 2024 12:25:01 -0800 (PST) X-Received: by 2002:a05:6402:1a28:b0:55c:2955:c6ba with SMTP id be8-20020a0564021a2800b0055c2955c6bamr844920edb.50.1706041500977; Tue, 23 Jan 2024 12:25:00 -0800 (PST) Precedence: bulk X-Mailing-List: linux-toolchains@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <9162660e-2d6b-47a3-bfa2-77bfc55c817b@paulmck-laptop> <57324f9b-c851-4120-82b6-dbbf21cb2720@zytor.com> In-Reply-To: <57324f9b-c851-4120-82b6-dbbf21cb2720@zytor.com> From: Linus Torvalds Date: Tue, 23 Jan 2024 12:24:44 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: A few proposals from the C standards committee To: "H. Peter Anvin" Cc: paulmck@kernel.org, linux-toolchains@vger.kernel.org, peterz@infradead.org, rostedt@goodmis.org, gregkh@linuxfoundation.org, keescook@chromium.org Content-Type: text/plain; charset="UTF-8" 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). Linus