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From: Arnd Bergmann <arnd@arndb.de>
To: Nathan Chancellor <natechancellor@gmail.com>
Cc: "Herbert Xu" <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>,
	"David Sterba" <dsterba@suse.com>,
	"Horia Geantă" <horia.geanta@nxp.com>,
	"Eric Biggers" <ebiggers@google.com>,
	"open list:HARDWARE RANDOM NUMBER GENERATOR CORE"
	<linux-crypto@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	clang-built-linux <clang-built-linux@googlegroups.com>
Subject: Re: [PATCH] crypto: blake2b - Fix clang optimization for ARMv7-M
Date: Fri, 8 May 2020 23:31:07 +0200	[thread overview]
Message-ID: <CAK8P3a2LAgEG7epWFtUZrcgk9OwpVJd+ji9Ru_rq4L-Qk_dYbg@mail.gmail.com> (raw)
In-Reply-To: <20200506051200.GA831492@ubuntu-s3-xlarge-x86>

On Wed, May 6, 2020 at 7:12 AM Nathan Chancellor
<natechancellor@gmail.com> wrote:
> > -
> > +#ifdef CONFIG_CC_IS_CLANG
>
> Given your comment in the bug:
>
> "The code is written to assume no loops are unrolled"
>
> Does it make sense to make this unconditional and take compiler
> heuristics out of it?
>
> > +#pragma nounroll /* https://bugs.llvm.org/show_bug.cgi?id=45803 */
> > +#endif
> >       for (i = 0; i < 8; ++i)
> >               S->h[i] = S->h[i] ^ v[i] ^ v[i + 8];

No, that would not work, as gcc does not support this pragma.

        Arnd

  reply	other threads:[~2020-05-08 21:31 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-05 13:53 [PATCH] crypto: blake2b - Fix clang optimization for ARMv7-M Arnd Bergmann
2020-05-06  5:12 ` Nathan Chancellor
2020-05-08 21:31   ` Arnd Bergmann [this message]
2020-05-09  1:43     ` Nathan Chancellor
2020-05-15  6:20 ` Herbert Xu

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