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Re: [PATCH 2/2] target/arm: Fix VUDOT/VSDOT (scalar) on big-endian hosts

From: Philippe Mathieu-Daudé
Subject: Re: [PATCH 2/2] target/arm: Fix VUDOT/VSDOT (scalar) on big-endian hosts
Date: Wed, 28 Oct 2020 20:51:23 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.3.1

On 10/28/20 8:17 PM, Peter Maydell wrote:
> The helper functions for performing the udot/sdot operations against
> a scalar were not using an address-swizzling macro when converting
> the index of the scalar element into a pointer into the vm array.
> This had no effect on little-endian hosts but meant we generated
> incorrect results on big-endian hosts.
> For these insns, the index is indexing over group of 4 8-bit values,
> so 32 bits per indexed entity, and H4() is therefore what we want.
> (For Neon the only possible input indexes are 0 and 1.)
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> I believe that gvec_udot_idx_h and gvec_sdot_idx_h are OK
> because the index there is over groups of 4*16-bit values,
> which are 64 bits each.
> ---
>  target/arm/vec_helper.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

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