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Message-ID: <nycvar.YSQ.7.76.1811060823150.1498@knanqh.ubzr>
Date: Tue, 6 Nov 2018 08:25:12 -0500 (EST)
From: Nicolas Pitre <nicolas.pitre@...aro.org>
To: Robin Murphy <robin.murphy@....com>
cc: Stefan Agner <stefan@...er.ch>, Arnd Bergmann <arnd@...db.de>,
Roman Yeryomin <roman@...em.lv>,
Linus Walleij <linus.walleij@...aro.org>,
Russell King - ARM Linux <linux@...linux.org.uk>,
linux-kernel@...r.kernel.org, Joel Stanley <joel@....id.au>,
Hans Ulli Kroll <ulli.kroll@...glemail.com>,
Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 1/2] ARM: copypage-fa: add kto and kfrom to input operands
list
On Tue, 6 Nov 2018, Robin Murphy wrote:
> On 06/11/2018 04:49, Nicolas Pitre wrote:
> [...]
> >> r3 and r5 are not used above, so no need to have them in the clobber
> >> list.
> >
> > They are used. ldrd and strd instructions always use a pair of
> > consecutive registers. So "ldrd r2, ..." loads into r2-r3 and "ldrd r4, ..."
> > loads into r4-r5.
>
> FWIW, since we should now be enabling unified syntax everywhere, I guess we
> could probably rewrite all those ldrd/strd to the UAL 3-operand form - i.e.
> "ldrd r2, r3, [...]" - if we really cared for the extra clarity.
Good idea. Worthy of a separate patch though.
Nicolas
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