[llvm-dev] [RFC] Extending shufflevector for vscale vectors (SVE etc.)

[Eli Friedman via llvm-dev]

> -----Original Message-----
> From: Richard Sandiford <richard.sandiford at arm.com>
> Sent: Thursday, January 30, 2020 3:36 AM
> To: Eli Friedman via llvm-dev <llvm-dev at lists.llvm.org>
> Cc: Eli Friedman <efriedma at quicinc.com>
> Subject: [EXT] Re: [llvm-dev] [RFC] Extending shufflevector for vscale vectors
> (SVE etc.)
>
> Eli Friedman via llvm-dev <llvm-dev at lists.llvm.org> writes:
> > [...]
> > We can add more shuffles to the list.  There are a few SVE shuffle
> > instructions which are not equivalent to any of the basic operations
> > I've listed: ext and trn.
>
> I realise this wasn't supposed to be an exhaustive list, but FWIW:
> revb, revh and revw are also useful for reversing each sequence
> of N elements (as opposed to reversing the whole vector).

revb is technically already exposed as a target-independent intrinsic (llvm.bswap), but yes, I missed those.

-Eli