Re: [isocpp-parallel] Proposal for new memory_order_consume definition

From	Lawrence Crowl <Lawrence@Crowl.org>
Newsgroups	linux.kernel
Subject	Re: [isocpp-parallel] Proposal for new memory_order_consume definition
Date	2016-02-29 20:40 +0100
Message-ID	<r7BPH-7hF-1@gated-at.bofh.it> (permalink)
References	(4 earlier) <r6Qxs-6i3-19@gated-at.bofh.it> <r6Wjw-1MZ-15@gated-at.bofh.it> <r6Wjw-1MZ-13@gated-at.bofh.it> <r74TL-80Z-1@gated-at.bofh.it> <r7ceB-57l-11@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 2/28/16, Linus Torvalds <torvalds@linux-foundation.org> wrote:
> The fact is, undefined compiler behavior is never a good idea. Not for
> serious projects.

Actually, undefined behavior is essential for serious projects, but
not for the reasons mentioned.

If the language has no undefined behavior, then from the compiler's view,
there is no such thing as a bad program.  All programs will compile and
enter functional debug (possibly after shipping to customer).  On the
other hand, a language with undefined behavior makes it possible for
compilers (and their run-time support) to identify a program as wrong.

The problem with the latest spate of compiler optimizations was not the
optimization, but the lack of warnings about exploiting undefined behavior.

-- 
Lawrence Crowl

Thread

Re: [isocpp-parallel] Proposal for new memory_order_consume  definition "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-02-27 18:10 +0100
  Re: [isocpp-parallel] Proposal for new memory_order_consume  definition "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-02-28 00:20 +0100
    Re: [isocpp-parallel] Proposal for new memory_order_consume  definition Markus Trippelsdorf <markus@trippelsdorf.de> - 2016-02-28 09:30 +0100
      Re: [isocpp-parallel] Proposal for new memory_order_consume definition Linus Torvalds <torvalds@linux-foundation.org> - 2016-02-28 17:20 +0100
        Re: [llvm-dev] [isocpp-parallel] Proposal for new memory_order_consume definition cbergstrom@pathscale.com - 2016-02-28 18:00 +0100
        Re: [isocpp-parallel] Proposal for new memory_order_consume  definition Michael Matz <matz@suse.de> - 2016-02-29 18:40 +0100
          Re: [isocpp-parallel] Proposal for new memory_order_consume definition Linus Torvalds <torvalds@linux-foundation.org> - 2016-02-29 19:00 +0100
        Re: [isocpp-parallel] Proposal for new memory_order_consume definition Lawrence Crowl <Lawrence@Crowl.org> - 2016-02-29 20:40 +0100
          Re: [llvm-dev] [isocpp-parallel] Proposal for new memory_order_consume  definition James Y Knight <jyknight@google.com> - 2016-02-29 22:20 +0100
        Re: [isocpp-parallel] Proposal for new memory_order_consume  definition Toon Moene <toon@moene.org> - 2016-02-29 22:40 +0100
  Re: [isocpp-parallel] Proposal for new memory_order_consume  definition Michael Matz <matz@suse.de> - 2016-02-29 19:20 +0100
    Re: [isocpp-parallel] Proposal for new memory_order_consume  definition "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-03-01 02:30 +0100

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