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[X86][Costmodel] Load/store i8 Stride=4 VF=16 interleaving costs
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Authored by lebedev.ri on Oct 1 2021, 1:27 PM.

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Summary

While we already model this tuple, the values are divergent from reality, so fix them.

The only sched models that for cpu's that support avx2
but not avx512 are: haswell, broadwell, skylake, zen1-3

For load we have:
https://godbolt.org/z/TrGW7cKsE - for intels Block RThroughput: =24.0; for ryzens, Block RThroughput: <=12.0
So pick cost of 24.

For store we have:
https://godbolt.org/z/Mh7qaqEfe - for intels Block RThroughput: =8.0; for ryzens, Block RThroughput: <=4.0
So pick cost of 8.

I'm directly using the shuffling asm the llc produced,
without any manual fixups that may be needed
to ensure sequential execution.

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