From: Robin Murphy <robin.murphy@arm.com>
To: Marc Gonzalez <marc.w.gonzalez@free.fr>,
Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Jens Axboe <axboe@kernel.dk>, Marc Zyngier <marc.zyngier@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
LKML <linux-kernel@vger.kernel.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Jeffrey Hugo <jhugo@codeaurora.org>,
MSM <linux-arm-msm@vger.kernel.org>,
AngeloGioacchino Del Regno <kholk11@gmail.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] arm64/io: Don't use WZR in writel
Date: Mon, 18 Mar 2019 17:59:17 +0000 [thread overview]
Message-ID: <0c06cb51-fc33-f2ba-e2b8-ad280b89f35c@arm.com> (raw)
In-Reply-To: <fbacd3df-41c4-f98a-8875-db654aff3a5c@free.fr>
On 18/03/2019 17:30, Marc Gonzalez wrote:
> On 18/03/2019 18:19, Robin Murphy wrote:
>
>> For the context bank reset, yes, I am assuming that no complier will
>> ever be perverse enough to detect that cfg is not written after the
>> NULL check and immediately reallocate it to XZR for no good reason.
>> I'd like to think that assumption is going to hold for the reasonable
>> scope of this particular workaround, though.
>
> I'm not sure I understand the above paragraph.
>
> In code such as:
>
> if (val == 0) foo(val);
>
> gcc's algorithm is likely to figure out that the code is equivalent to
>
> if (val == 0) foo(0)
>
> and perform constant-propagation, etc.
>
> Is that what we're talking about?
As may already be apparent, the way I expect compilers to behave, and
the way compilers actually behave, are two overlapping but distinct sets
of concepts...
Robin.
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next prev parent reply other threads:[~2019-03-18 17:59 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-09 18:34 [PATCH] arm64/io: Don't use WZR in writel AngeloGioacchino Del Regno
2019-02-11 10:57 ` Will Deacon
2019-02-11 11:52 ` Marc Zyngier
2019-02-11 14:29 ` AngeloGioacchino Del Regno
2019-02-11 14:59 ` Marc Zyngier
2019-02-11 16:15 ` AngeloGioacchino Del Regno
2019-02-11 16:37 ` Robin Murphy
2019-02-23 18:12 ` Bjorn Andersson
2019-02-23 18:37 ` Marc Zyngier
2019-02-24 3:53 ` Bjorn Andersson
2019-03-12 12:36 ` Marc Gonzalez
2019-03-18 16:04 ` Robin Murphy
2019-03-18 17:00 ` Russell King - ARM Linux admin
2019-03-18 17:11 ` Ard Biesheuvel
2019-03-18 17:19 ` Robin Murphy
2019-03-18 17:24 ` Robin Murphy
2019-03-19 11:45 ` Robin Murphy
2019-03-18 17:30 ` Marc Gonzalez
2019-03-18 17:59 ` Robin Murphy [this message]
2019-05-02 16:05 ` Marc Gonzalez
2019-05-02 16:33 ` Robin Murphy
2019-05-02 16:50 ` Marc Gonzalez
2019-05-03 11:36 ` Marc Gonzalez
2019-05-03 12:48 ` Robin Murphy
2019-05-03 13:07 ` Marc Gonzalez
2019-05-04 13:35 ` AngeloGioacchino Del Regno
2019-05-05 18:05 ` AngeloGioacchino Del Regno
2019-05-20 15:05 ` Marc Gonzalez
2019-05-02 17:27 ` Marc Gonzalez
2019-05-03 0:38 ` Bjorn Andersson
-- strict thread matches above, loose matches on Subject: below --
2019-02-09 18:30 AngeloGioacchino Del Regno
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