From: Richard Biener <richard.guenther@gmail.com>
To: Mikael Morin <morin-mikael@orange.fr>
Cc: Thomas Koenig <tkoenig@netcologne.de>,
Mikael Morin <mikael@gcc.gnu.org>,
gcc-patches@gcc.gnu.org, fortran@gcc.gnu.org
Subject: Re: [PATCH 09/10] fortran: Support clobbering of variable subreferences [PR88364]
Date: Sun, 18 Sep 2022 12:48:19 +0200 [thread overview]
Message-ID: <AC4EE9CD-A104-4238-95E5-5A83CECD5A17@gmail.com> (raw)
In-Reply-To: <a7b611fe-50bd-8047-73b1-a0c0f3a884e5@orange.fr>
> Am 18.09.2022 um 11:10 schrieb Mikael Morin <morin-mikael@orange.fr>:
>
> Le 18/09/2022 à 08:12, Richard Biener a écrit :
>>> On Sat, Sep 17, 2022 at 9:33 PM Mikael Morin <morin-mikael@orange.fr> wrote:
>>>
>>> Le 17/09/2022 à 19:03, Thomas Koenig via Fortran a écrit :
>>>>
>>>> I have a concern about this part, though. My understanding at the
>>>> time was that it is not possible to clobber an individual array
>>>> element, but that this clobbers anything off the pointer that this
>>>> is based on.
>>>>
>>> Well, we need the middle-end guys to give a definitive answer on this
>>> topic, but I think it would be a very penalizing limitation if that was
>>> the case. I have assumed that the clobber spanned the value it was
>>> applied on, neither more nor less, so just the array element in case of
>>> array elements.
>> There is IL verification that the LHS of a CLOBBER is either
>> a declaration or a pointer dereference, no array or component
>> selection is allowed there. Now, nothing should go wrong here,
>> but we might eventually just drop those CLOBBERs or ICE if
>> we frontend hands us an "invalid" one.
>
> Obviously I have assumed too much here; it's probably best to drop this patch.
> It is unfortunate as there is some desirable behavior within reach here. The test shows that the patch permits the elimination of a useless store. And IL verification doesn't seem that upset with it by the way.
> Does *(&a[1]) count as a pointer dereference?
Yes, technically.
> Even in the original dump it is already simplified to a straight a[1].
But this not anymore. The check can probably be relaxed, it stems from the dual purpose of CLOBBER.
Richard
next prev parent reply other threads:[~2022-09-18 10:48 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-16 20:24 [PATCH 00/10] fortran: clobber fixes [PR41453] Mikael Morin
2022-09-16 20:24 ` [PATCH 01/10] fortran: Move the clobber generation code Mikael Morin
2022-09-16 20:24 ` [PATCH 02/10] fortran: Fix invalid function decl clobber ICE [PR105012] Mikael Morin
2022-09-16 20:24 ` [PATCH 03/10] fortran: Move clobbers after evaluation of all arguments [PR106817] Mikael Morin
2022-09-16 20:24 ` [PATCH 04/10] fortran: Support clobbering with implicit interfaces [PR105012] Mikael Morin
2022-09-16 20:24 ` [PATCH 05/10] fortran: Support clobbering of reference variables [PR41453] Mikael Morin
2022-09-16 20:24 ` [PATCH 06/10] fortran: Support clobbering of SAVE variables [PR87395] Mikael Morin
2022-09-16 20:24 ` [PATCH 07/10] fortran: Support clobbering of ASSOCIATE variables [PR87397] Mikael Morin
2022-09-16 20:24 ` [PATCH 08/10] fortran: Support clobbering of allocatables and pointers [PR41453] Mikael Morin
2022-09-16 20:24 ` [PATCH 09/10] fortran: Support clobbering of variable subreferences [PR88364] Mikael Morin
2022-09-17 17:03 ` Thomas Koenig
2022-09-17 19:33 ` Mikael Morin
2022-09-17 19:49 ` Bernhard Reutner-Fischer
2022-09-17 19:50 ` Mikael Morin
2022-09-17 21:24 ` Bernhard Reutner-Fischer
2022-09-18 6:12 ` Richard Biener
2022-09-18 9:10 ` Mikael Morin
2022-09-18 10:23 ` Thomas Koenig
2022-09-18 18:32 ` Harald Anlauf
2022-09-18 20:55 ` Mikael Morin
2022-09-19 7:11 ` Mikael Morin
2022-09-19 19:46 ` Harald Anlauf
2022-09-19 20:50 ` Mikael Morin
2022-09-20 6:54 ` Thomas Koenig
2022-09-20 8:46 ` Mikael Morin
2022-09-20 21:08 ` Harald Anlauf
2022-09-20 21:08 ` Harald Anlauf
2022-09-21 9:57 ` Thomas Koenig
2022-09-21 18:56 ` Mikael Morin
2022-09-21 19:12 ` Harald Anlauf
2022-09-21 19:12 ` Harald Anlauf
2022-09-18 20:43 ` Mikael Morin
2022-09-18 10:48 ` Richard Biener [this message]
2022-09-19 7:31 ` Mikael Morin
2022-09-19 7:58 ` Richard Biener
2022-09-16 20:24 ` [PATCH 10/10] fortran: Support clobbering of derived types [PR41453] Mikael Morin
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