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From: Thomas Huth <thuth@redhat.com>
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Date: Mon, 20 Jun 2016 10:21:44 +0200
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Subject: Re: [Qemu-devel] [PULL 03/13] target-ppc: Use 32-bit rotate instead
 of deposit + 64-bit rotate
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To: Anton Blanchard <anton@samba.org>, Richard Henderson <rth@twiddle.net>
Cc: qemu-devel@nongnu.org, peter.maydell@linaro.org, qemu-ppc@nongnu.org, agraf@suse.de, David Gibson <david@gibson.dropbear.id.au>

On 18.06.2016 06:02, Anton Blanchard wrote:
> Hi,
> 
>>>> Bother.  I've tentatively put a revert into ppc-for-2.7.  Richard,
>>>> do you have a better idea how to fix it?    
>>>
>>> Please try the following.  
>>
>> Thanks! This passes my tests. Feel free to add:
>>
>> Tested-by: Anton Blanchard <anton@samba.org>
> 
> Actually I think I've found a problem:
> 
>         lis     r4,0x7fffffff@h
>         ori     r4,r4,0x7fffffff@l
>         rlwinm  r3,r4,0,25,1
> 
> 32 bit rotate is defined as a 64 bit rotate of 2 copies of the 32 bit
> value, so we expect 0x7fffffff4000007f, but get 0x4000007f.
> 
> Not sure if anything out there depends on it though.

Would it maybe make sense to add some tests for this stuff to the
tests/tcg/ folder to make sure that such regressions do not sneak back
in in the future?

 Thomas