[PATCH] D81992: [AArch64][GlobalISel] Make G_SEXT_INREG legal and add selection support.

[Amara Emerson via Phabricator via llvm-commits]

aemerson added a comment.

In D81992#2114675 <https://reviews.llvm.org/D81992#2114675>, @john.brawn wrote:>

>   %6:_(s32) = nsw G_SUB %3:_, %5:_
>   %7:_(s16) = G_TRUNC %6:_(s32)
>   %8:_(s64) = G_SEXT %7:_(s16)
>   
>
> which then gets converted to
>
>   %6:_(s32) = nsw G_SUB %3:_, %5:_
>   %16:_(s64) = G_ANYEXT %6:_(s32)
>   %8:_(s64) = G_SEXT_INREG %16:_, 16
>   
>
> The truncation has been lost, and we eventually end up with


The anyext is fine there, the SEXT_INREG should do the right thing and sign extend from bit 16, however it looks like we have a bug in the selector in this case. Fix incoming.


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  https://reviews.llvm.org/D81992/new/

https://reviews.llvm.org/D81992