[LLVMdev] Selecting Vector Shuffle of Different Types

David Greene dag at cray.com
Thu Dec 3 09:22:32 PST 2009

On Wednesday 02 December 2009 18:26, Eli Friedman wrote:

> > Well, it's right!  So how do I express this kind of thing?  Since LLVM
> > 2.5 shufflevector supports creating a vector of a difference size than
> > the inputs.  Which is exactly what we need for VEXTRACTF128 and
> > VINSERTF128.
> Perhaps EXTRACT_SUBVECTOR would be more appropriate here?

Except there's no upper 128-bit subvector of a ymm register, which is why we 
need VEXTRACTF128 / VINSERTF128.  It's a big pain in the rear.


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