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Re: ARM SVE issues with non "standard" vector lengths

From: Laurent Desnogues
Subject: Re: ARM SVE issues with non "standard" vector lengths
Date: Thu, 23 Apr 2020 18:24:52 +0200

On Thu, Apr 23, 2020 at 5:19 PM Richard Henderson
<address@hidden> wrote:
> On 4/23/20 6:59 AM, Laurent Desnogues wrote:
> > 2. sve_zip_p
> >
> > This generates extraneous data in the higher part of the result.
> >
> > I hit this when I got a wrong result on an instruction that ends up
> > using sve_cntp which counts all bits set in each 64-bit chunk. There
> > might be some other instructions beyond ZIP that generate extra data
> > that would break sve_cntp.  So perhaps it'd be easier to fix sve_cmtp
> > (and hope that it's the only function that uses bits beyond vector
> > length...).
> There are quite a few places that assume (and some that assert, such as the
> load/store paths) that there are no predicate bits set beyond VL.
> I will fix zip.

Looking at the code I think sve_punpk_p is affected too.



> r~

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