From: Richard Henderson <rth@twiddle.net>
To: John Regehr <regehr@cs.utah.edu>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] possible qemu miscompilation by latest gcc
Date: Thu, 21 Jan 2010 08:57:32 -0800 [thread overview]
Message-ID: <4B58877C.5060408@twiddle.net> (raw)
In-Reply-To: <4B57F0EB.1050905@cs.utah.edu>
On 01/20/2010 10:15 PM, John Regehr wrote:
> Hi folks-
>
> Just wanted to let you know that perhaps the function
> helper_neon_rshl_s8() is being miscompiled by the latest gcc.
>
> I'm using qemu 0.12.2 and gcc rev 156103, which is a pre-version of gcc
> 4.5. This is on an x86 machine running Ubuntu 9.10.
>
> At -O2 or higher this is the resulting object code:
>
> 00002060 <helper_neon_rshl_s8>:
> 2060: 31 c0 xor %eax,%eax
> 2062: c3 ret
>
> If this is not the intended result, then either the function has a
> latent bug or else the compiler is doing something bad.
Confirmed. The compiler is at fault.
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42833
r~
prev parent reply other threads:[~2010-01-21 16:58 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-21 6:15 [Qemu-devel] possible qemu miscompilation by latest gcc John Regehr
2010-01-21 16:57 ` Richard Henderson [this message]
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