From: Segher Boessenkool <segher@kernel.crashing.org>
To: Alexander Monakov <amonakov@ispras.ru>
Cc: Jakub Jelinek <jakub@redhat.com>, Martin Sebor <msebor@gmail.com>,
Gcc Patch List <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] diagnose unsupported uses of hardware register variables (PR 88000)
Date: Wed, 14 Nov 2018 17:47:00 -0000 [thread overview]
Message-ID: <20181114174723.GD23873@gate.crashing.org> (raw)
In-Reply-To: <alpine.LNX.2.20.13.1811141658570.10221@monopod.intra.ispras.ru>
On Wed, Nov 14, 2018 at 06:50:38PM +0300, Alexander Monakov wrote:
> On Wed, 14 Nov 2018, Segher Boessenkool wrote:
> > > I think with "=g" rather than "+g" this example is ok.
> >
> > No, it needs the register var as an input. That is the whole *point*.
>
> Hm. I think I see what you meant, but "+g" is not correct either: the
> asm, by intent, depends *on the current value in the 'sp' hardreg*, not
> *on the current value of some automatic variable that is supposed to be
> passed on the 'sp' hardreg to the asm* (which is what expressed by the
> input constraint).
Yeah, using local register vars to access global registers only works
by accident. It does work currently though, and people apparently use
it, so we shouldn't break it :-/
Segher
next prev parent reply other threads:[~2018-11-14 17:47 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-14 12:22 Segher Boessenkool
2018-11-14 12:27 ` Jakub Jelinek
2018-11-14 12:33 ` Alexander Monakov
2018-11-14 13:53 ` Segher Boessenkool
2018-11-14 15:50 ` Alexander Monakov
2018-11-14 17:47 ` Segher Boessenkool [this message]
2018-11-14 18:01 ` Alexander Monakov
2018-11-15 15:54 ` Michael Matz
2018-11-15 16:23 ` Alexander Monakov
2018-11-16 15:21 ` Michael Matz
2018-11-16 16:28 ` Alexander Monakov
2018-11-16 16:43 ` Michael Matz
2018-11-16 22:12 ` Segher Boessenkool
2018-11-19 12:59 ` Michael Matz
2018-11-19 17:18 ` Segher Boessenkool
2018-11-14 13:47 ` Segher Boessenkool
-- strict thread matches above, loose matches on Subject: below --
2018-11-14 4:11 Martin Sebor
2018-11-14 9:39 ` Alexander Monakov
2018-11-15 22:34 ` Martin Sebor
2018-11-14 9:48 ` Jakub Jelinek
2018-11-14 11:35 ` Segher Boessenkool
2018-11-14 11:40 ` Jakub Jelinek
2018-11-14 11:50 ` Segher Boessenkool
2018-11-14 12:00 ` Jakub Jelinek
2018-11-14 12:11 ` Segher Boessenkool
2018-11-14 12:14 ` Jakub Jelinek
2018-11-15 18:31 ` Martin Sebor
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