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Re: [Qemu-ppc] [RFC PATCH v2 4/9] target/ppc: delay writeback of avr{l,

From: Richard Henderson
Subject: Re: [Qemu-ppc] [RFC PATCH v2 4/9] target/ppc: delay writeback of avr{l, h} during lvx instruction
Date: Mon, 17 Dec 2018 08:46:17 -0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.1

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>


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