Re: volk and alignment

[Marcus Müller]

Hi Thomas,

hadn't taken the time to respond yet, sorry about that!

> Is there a maximum size that volk_get_alignment could return, a size
> that's reasonable?

I'd go with "realistically, yes, but isn't relying on that a bad idea?".

I'm thinking back and forth about how to address that problem.
Basically, what we'd need is a "worst case of all available machines" 
alignment, that is present in an integer constant expression, so you can 
put it into alignas(), right?

Best regards,
Marcus

On 06/07/2020 11.28, Thomas Habets wrote:
> While doing https://github.com/gnuradio/gnuradio/pull/3619 it 
> occurred to me that some dynamic volk_malloc (volk::vector<>) should be 
> doable as stack allocations. There's nothing magic about the 
> allocations, they're just aligned.
>
> Is there a maximum size that volk_get_alignment could return, a size 
> that's reasonable?
>
> The reason I ask is that if it's "yes: 64", then calling code would be 
> cleaner when all it needs is a temporary but aligned space.
>
> E.g.
> https://github.com/gnuradio/gnuradio/blob/master/gr-filter/lib/fir_filter.cc#L103
> could skip the d_output member, and instead just have local variable 
> `alignas(64) float tmp;`.
>
>
>
> --
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>   char coolcmd[]   = { "echo '. ./_&. ./_'>_;. ./_" };
> } me_t;

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