Make LowerSIGN_EXTEND_INREG split 256-bit vectors when AVX1 is enabled and use AVX2 shifts when AVX2 is enabled.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@145022 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed