[X86] Remove ISD::INSERT_SUBVECTOR handling from combineBitcastForMaskedOp. Add isel patterns to make up for it.

This will allow for some flexibility in canonicalizing bitcasts around insert_subvector.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315160 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed