[DAGCombiner] (insert_vector_elt (vector_shuffle X, Y), (extract_vector_elt X,...

[DAGCombiner] (insert_vector_elt (vector_shuffle X, Y), (extract_vector_elt X, N), IdxC) -> (vector_shuffle X, Y)

Summary: This is beneficial when the shuffle is only used once and end up being generated in a few places when some node is combined into a shuffle.

Reviewers: craig.topper, efriedma, RKSimon, lebedev.ri

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66718

llvm-svn: 370326