Re: [Qemu-devel] [PATCH v3 0/6] target-arm: Fix Neon shift instructions.

[Christophe Lyon <christophe.lyon@st.com>]

On 14.02.2011 19:18, Peter Maydell wrote:
> On 11 February 2011 15:10,  <christophe.lyon@st.com> wrote:
>> From: Christophe Lyon <christophe.lyon@st.com>
>>
>> This patch series provides fixes such that ARM Neon instructions
>> VRSHR, VRSRA, VQRSHRN, VQRSHRUN, VRSHRN, VQSHRN, VSHRN, VQSHRUN now
>> pass all my tests.
>>
>> I have reworked all these patches and I hope they are now easier to
>> review.
> 
> Thanks; this was indeed a lot easier to review. Mostly
> this is OK, there are a few things:
>  * minor style issues
>  * handling of very large shift counts is not right
> (both in code you wrote and existing routines)

Yes, I mostly copied existing code to fix the parts I identified as wrong, but indeed very large shift amounts are not part of my tests.

>  * the shift-and-narrow loop doesn't handle the case
> where pass 1 reads registers pass 0 writes
> 
> I have patches which (sitting on top of your 6) fix all
> these and give a clean pass on the random instruction
> set testing for the shift instructions.
> 
> Unless you object, I think the simplest thing will be for
> me to just fix the minor nits I identified in your patches
> and then post a combined series of your patches and
> mine.
OK, thanks.

It also seems that the neon_shl_s* helpers don't handle correctly large negative shift amounts.

Christophe.