[llvm] SelectionDAG: Support FMINIMUMNUM and FMINIMUM in combineMinNumMaxNumImpl (PR #137449)

[YunQiang Su via llvm-commits]

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wzssyqa wrote:

@arsenm 
I noticed that `TransformVT` is used since
commit cea7c6969d777615b0a29584b1be4c90ea968944
Author: Matt Arsenault <Matthew.Arsenault at amd.com>
Date:   Mon Aug 27 18:11:31 2018 +0000

    DAG: Check transformed type for forming fminnum/fmaxnum from vselect
    
    Follow up to r340655 to fix vector types which are split.
    
    llvm-svn: 340766

While when we add _IEEE support, `TransformVT` is not used then. 

https://github.com/llvm/llvm-project/pull/137449