[X86] Add some cost model entries for sext/zext for avx512bw
This fixes some of scalarization costs reported for sext/zext using avx512bw. This does not fix all scalarization costs being reported. Just the worst.
I've restricted this only to combinations of types that are legal with avx512bw like v32i1/v64i1/v32i16/v64i8 and conversions between vXi1 and vXi8/vXi16 with legal vXi8/vXi16 result types.
Differential Revision: https://reviews.llvm.org/D54979
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@347785 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed