From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Paul E. McKenney" <paulmck@linux.ibm.com>
Subject: Re: [RFC PATCH] tools/memory-model: Remove (dep ; rfi) from ppo
Date: Mon, 4 Mar 2019 08:09:47 -0800
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To: Akira Yokosawa <akiyks@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Borislav Petkov <bp@alien8.de>, Andrea Parri <andrea.parri@amarulasolutions.com>, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Alan Stern <stern@rowland.harvard.edu>, Will Deacon <will.deacon@arm.com>, Boqun Feng <boqun.feng@gmail.com>, Nicholas Piggin <npiggin@gmail.com>, David Howells <dhowells@redhat.com>, Jade Alglave <j.alglave@ucl.ac.uk>, Luc Maranget <luc.maranget@inria.fr>, Daniel Lustig <dlustig@nvidia.com>
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On Sun, Mar 03, 2019 at 12:27:12AM +0900, Akira Yokosawa wrote:
> Hello Peter,
> 
> On Tue, 26 Feb 2019 14:49:06 +0100, Peter Zijlstra wrote:
> > On Tue, Feb 26, 2019 at 12:38:13PM +0100, Borislav Petkov wrote:
> >> On Tue, Feb 26, 2019 at 12:30:08PM +0100, Peter Zijlstra wrote:
> >>> When I used the argc variant, gcc-8 'works', but with s/argc/1/ it is
> >>> still broken.
> >>
> >> As requested on IRC:
> > 
> > What I asked was if you could get your GCC developer friends to have a
> > look at this :-)
> 
> JFYI, there is a bugzilla ticket regarding this behavior of GCC
> at https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61502,
> which started on 13 June 2014 and the latest entry was on
> 02 Feb 2019.

And that bug was submitted by none other than Peter Sewell, thank you!

This bug references https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88775,
where someone appears to -want- this sort of optimization.  :-/

							Thanx, Paul