[LLVMdev] Selecting Vector Shuffle of Different Types

Nate Begeman natebegeman at mac.com
Wed Dec 2 17:19:57 PST 2009

On Dec 2, 2009, at 3:55 PM, Bob Wilson wrote:

> On Dec 2, 2009, at 3:46 PM, David Greene 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.
> I think the SelectionDAG vector_shuffle node still requires the vector types to match.  The LLVM IR shuffles can have a different size, but they are forced to match when building the SelectionDAG.

It would be really great if the SelectionDAG shuffle node had the same flexibility as the IR instruction, w.r.t. different sized inputs and outputs.


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