linux-kernel - Re: [PATCH] crypto: blake2b - Fix clang optimization for ARMv7-M

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Message-ID: <20200515062057.GA22330@gondor.apana.org.au>
Date:   Fri, 15 May 2020 16:20:57 +1000
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     "David S. Miller" <davem@...emloft.net>,
        David Sterba <dsterba@...e.com>,
        Horia Geantă <horia.geanta@....com>,
        Eric Biggers <ebiggers@...gle.com>,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com
Subject: Re: [PATCH] crypto: blake2b - Fix clang optimization for ARMv7-M

On Tue, May 05, 2020 at 03:53:45PM +0200, Arnd Bergmann wrote:
> When building for ARMv7-M, clang-9 or higher tries to unroll some loops,
> which ends up confusing the register allocator to the point of generating
> rather bad code and using more than the warning limit for stack frames:
> 
> warning: stack frame size of 1200 bytes in function 'blake2b_compress' [-Wframe-larger-than=]
> 
> Forcing it to not unroll the final loop avoids this problem.
> 
> Fixes: 91d689337fe8 ("crypto: blake2b - add blake2b generic implementation")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  crypto/blake2b_generic.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

Patch applied.  Thanks.
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
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