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Re: [Qemu-ppc] [Qemu-devel] [RFC PATCH v2 4/9] target/ppc: delay writeba

From: Mark Cave-Ayland
Subject: Re: [Qemu-ppc] [Qemu-devel] [RFC PATCH v2 4/9] target/ppc: delay writeback of avr{l, h} during lvx instruction
Date: Mon, 17 Dec 2018 17:23:36 +0000
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.0

On 17/12/2018 16:46, Richard Henderson wrote:

> On 12/17/18 4:24 AM, Mark Cave-Ayland wrote:
>> During review of the previous patch, Richard pointed out an existing bug that
>> the writeback to the avr{l,h} registers should be delayed until after any
>> exceptions have been raised.
>> Perform both 64-bit loads into separate temporaries and then write them into
>> the avr{l,h} registers together to ensure that this is always the case.
>> Signed-off-by: Mark Cave-Ayland <address@hidden>
>> ---
>>  target/ppc/translate/vmx-impl.inc.c | 24 +++++++++++++-----------
>>  1 file changed, 13 insertions(+), 11 deletions(-)
> I feel a bit silly.  There was no bug, since the address is forced to be
> aligned on a 16-byte boundary.  The second memory access will be to the same
> page and cannot trap.
> That said, I think the cleanup looks good.
> Reviewed-by: Richard Henderson <address@hidden>

Ah okay. I'm inclined to drop this patch for now, since it feels strange 
a cleanup to just one of the load functions...



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