[SelectionDAG] Fold insert_subvector(undef, extract_subvector(v, c), c) -> v in getNode

This is already done in DAGCombiner::visitINSERT_SUBVECTOR, but this helps a number of shuffles across different vector widths recognise when they come from the same source.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@363542 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed