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From: Julien Grall <julien.grall@arm.com>
To: Jan Beulich <JBeulich@suse.com>,
	Stefano Stabellini <sstabellini@kernel.org>
Cc: Juergen Gross <jgross@suse.com>,
	Stefano Stabellini <stefanos@xilinx.com>,
	Wei Liu <wei.liu2@citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Julien Grall <julien.grall@gmail.com>,
	Stewart Hildebrand <Stewart.Hildebrand@dornerworks.com>,
	xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH v6 1/4] xen: introduce SYMBOL
Date: Fri, 18 Jan 2019 10:48:57 +0000	[thread overview]
Message-ID: <ca2ed7b7-f0b6-6b06-a306-b7c693e354b1@arm.com> (raw)
In-Reply-To: <5C41A256020000780020EF25@prv1-mh.provo.novell.com>

Hi Jan,

On 18/01/2019 09:54, Jan Beulich wrote:
>>>> On 18.01.19 at 02:24, <sstabellini@kernel.org> wrote:
>> On Thu, 17 Jan 2019, Jan Beulich wrote:
>>>>>> On 17.01.19 at 01:37, <sstabellini@kernel.org> wrote:
>>>> On Wed, 16 Jan 2019, Jan Beulich wrote:
> Stop. No. We very much can prove they are - _end points at
> one past the last element of _start[]. It is the compiler which
> can't prove the opposite, and hence it can't leverage
> undefined behavior for optimization purposes.

You keep saying the compiler can't leverage it for optimization purpose, however 
there are confirmations that GCC may actually leverage it (e.g [1]). You 
actually need to trick the compiler to avoid the optimization (e.g RELOC_HIDE).

So obviously, this is not only a MISRA "problem" as you state here and below.

I believe Stefano, Stewart and I provided plenty of documentation/thread to 
support our positions. Can you provide us documentation/thread showing the 
compiler will not try to leverage that case?

Cheers,

[1] 
https://kristerw.blogspot.com/2016/12/pointer-comparison-invalid-optimization.html?m=1

-- 
Julien Grall

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  reply	other threads:[~2019-01-18 10:49 UTC|newest]

Thread overview: 102+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-09 23:41 [PATCH v6 0/4] misc safety certification fixes Stefano Stabellini
2019-01-09 23:42 ` [PATCH v6 1/4] xen: introduce SYMBOL Stefano Stabellini
2019-01-10  2:40   ` Julien Grall
2019-01-10  8:24     ` Jan Beulich
2019-01-10 17:29       ` Stefano Stabellini
2019-01-10 18:46         ` Stewart Hildebrand
2019-01-10 19:03           ` Stefano Stabellini
2019-01-11 10:35           ` Jan Beulich
2019-01-11 17:01             ` Stefano Stabellini
2019-01-10 19:24         ` Julien Grall
2019-01-10 21:36           ` Stefano Stabellini
2019-01-10 23:31             ` Julien Grall
2019-01-11  2:14               ` Stefano Stabellini
2019-01-11  6:52                 ` Juergen Gross
2019-01-11 16:52                   ` Stefano Stabellini
2019-01-11 10:48                 ` Jan Beulich
2019-01-11 18:04                   ` Stefano Stabellini
2019-01-11 18:53                     ` Stewart Hildebrand
2019-01-11 20:35                       ` Julien Grall
2019-01-11 20:46                         ` Stewart Hildebrand
2019-01-11 21:37                           ` Stefano Stabellini
2019-01-14  3:45                             ` Stewart Hildebrand
2019-01-14 10:26                               ` Jan Beulich
2019-01-14 21:18                                 ` Stefano Stabellini
     [not found]                                   ` <1CACC1FB020000D800417A66@prv1-mh.provo.novell.com>
2019-01-15  8:21                                     ` Jan Beulich
2019-01-15 11:51                                       ` Julien Grall
     [not found]                                         ` <AB1DA25B020000B95C475325@prv1-mh.provo.novell.com>
2019-01-15 12:04                                           ` Jan Beulich
2019-01-15 12:23                                             ` Julien Grall
     [not found]                                               ` <BAE986750200003A5C475325@prv1-mh.provo.novell.com>
2019-01-15 12:44                                                 ` Jan Beulich
2019-01-15 20:03                                       ` Stewart Hildebrand
2019-01-16  6:01                                         ` Juergen Gross
2019-01-16 10:19                                         ` Jan Beulich
2019-01-17  0:37                                           ` Stefano Stabellini
     [not found]                                             ` <B4D3ABC30200003B88BF86FB@prv1-mh.provo.novell.com>
     [not found]                                               ` <529ED2F90200004D00417A66@prv1-mh.provo.novell.com>
2019-01-17 11:45                                                 ` Jan Beulich
2019-01-18  1:24                                                   ` Stefano Stabellini
     [not found]                                                     ` <76A2DEED0200005600417A66@prv1-mh.provo.novell.com>
2019-01-18  9:54                                                       ` Jan Beulich
2019-01-18 10:48                                                         ` Julien Grall [this message]
     [not found]                                                           ` <9F511FC70200005E5C475325@prv1-mh.provo.novell.com>
2019-01-18 11:09                                                             ` Jan Beulich
2019-01-18 15:22                                                               ` Julien Grall
     [not found]                                                                 ` <3A8206D8020000035C475325@prv1-mh.provo.novell.com>
2019-01-21  9:39                                                                   ` Jan Beulich
2019-01-21  9:34                                                             ` Jan Beulich
2019-01-21 10:22                                                               ` Julien Grall
     [not found]                                                                 ` <E16AB350020000435C475325@prv1-mh.provo.novell.com>
2019-01-21 10:31                                                                   ` Jan Beulich
2019-01-21 23:15                                                                     ` Stefano Stabellini
     [not found]                                                                       ` <5EA2B4FA0200008000417A66@prv1-mh.provo.novell.com>
2019-01-22  9:06                                                                         ` Jan Beulich
2019-01-18 23:05                                                         ` Stefano Stabellini
2019-01-21  5:24                                                           ` Stewart Hildebrand
     [not found]                                                           ` <5A96F2FD0200008D00417A66@prv1-mh.provo.novell.com>
2019-01-21  9:50                                                             ` Jan Beulich
2019-01-21 23:41                                                               ` Stefano Stabellini
2019-01-22  6:08                                                                 ` Juergen Gross
     [not found]                                                                 ` <42A2C4FA0200009000417A66@prv1-mh.provo.novell.com>
2019-01-22  9:16                                                                   ` Jan Beulich
2019-02-01 18:52                                                                     ` George Dunlap
2019-02-01 20:53                                                                       ` Stefano Stabellini
     [not found]                                                             ` <58377FAD0200004688BF86FB@prv1-mh.provo.novell.com>
2019-01-21 10:06                                                               ` Jan Beulich
2019-02-06 15:41                                                                 ` Ian Jackson
     [not found]                                           ` <C8F95655020000CAB8D7C7D4@prv1-mh.provo.novell.com>
     [not found]                                             ` <5867EFE6020000DB00417A66@prv1-mh.provo.novell.com>
     [not found]                                               ` <DACE7A5F020000B1B8D7C7D4@prv1-mh.provo.novell.com>
2019-02-07 14:51                                                 ` Jan Beulich
2019-01-15 23:36                                       ` Stefano Stabellini
2019-01-16  8:47                                         ` Juergen Gross
     [not found]                                         ` <2EA6D6FD0200001F00417A66@prv1-mh.provo.novell.com>
2019-01-16 10:25                                           ` Jan Beulich
2019-01-17  0:41                                             ` Stefano Stabellini
     [not found]                                               ` <4EA2F2F90200004D00417A66@prv1-mh.provo.novell.com>
2019-01-17 11:46                                                 ` Jan Beulich
     [not found]                                     ` <95DC675902000028AB59E961@prv1-mh.provo.novell.com>
2019-02-04  9:37                                       ` Jan Beulich
2019-02-04 19:08                                         ` Stefano Stabellini
2019-02-05  6:02                                           ` Juergen Gross
     [not found]                                           ` <2E9DDEFD0200007B00417A66@prv1-mh.provo.novell.com>
2019-02-05  7:53                                             ` Jan Beulich
2019-02-05 14:56                                         ` George Dunlap
     [not found]                                           ` <E730A9F90200001DAB59E961@prv1-mh.provo.novell.com>
2019-02-06 11:59                                             ` Jan Beulich
     [not found]                                 ` <7A8C0A4F020000EEB8D7C7D4@prv1-mh.provo.novell.com>
2019-02-06 16:21                                   ` Jan Beulich
2019-02-06 16:37                                     ` Ian Jackson
     [not found]                                       ` <08D440470200001BB8D7C7D4@prv1-mh.provo.novell.com>
2019-02-06 16:47                                         ` Jan Beulich
2019-02-06 16:52                                           ` Ian Jackson
2019-02-06 23:39                                             ` Stefano Stabellini
2019-02-07 11:48                                               ` Ian Jackson
2019-02-07 18:18                                                 ` Stefano Stabellini
2019-02-12 11:31                                                   ` Ian Jackson
2019-02-13  0:09                                                     ` Stefano Stabellini
2019-01-15 11:46                             ` Julien Grall
2019-01-15 12:23                               ` Julien Grall
2019-01-14 10:11                     ` Jan Beulich
2019-01-14 15:41                       ` Julien Grall
2019-01-14 15:52                         ` Jan Beulich
2019-01-14 16:26                           ` Stewart Hildebrand
2019-01-14 16:39                             ` Jan Beulich
2019-01-14 16:28                           ` Julien Grall
2019-01-14 16:44                             ` Jan Beulich
2019-01-14 17:24                               ` Julien Grall
2019-01-15  8:04                                 ` Jan Beulich
2019-01-10 17:22     ` Stefano Stabellini
2019-01-10  8:34   ` Jan Beulich
2019-01-10 18:09     ` Stefano Stabellini
2019-01-09 23:42 ` [PATCH v6 2/4] xen/arm: use SYMBOL when required Stefano Stabellini
2019-01-10  8:41   ` Jan Beulich
2019-01-10 17:44     ` Stefano Stabellini
2019-01-11 10:52       ` Jan Beulich
2019-01-11 16:58         ` Stefano Stabellini
2019-01-14  9:23           ` Jan Beulich
2019-01-09 23:42 ` [PATCH v6 3/4] xen/x86: " Stefano Stabellini
2019-01-10  8:43   ` Jan Beulich
2019-01-10 17:45     ` Stefano Stabellini
2019-01-09 23:42 ` [PATCH v6 4/4] xen/common: " Stefano Stabellini
2019-01-10  8:49   ` Jan Beulich
2019-01-10 17:48     ` Stefano Stabellini

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