[X86][AVX] createVariablePermute - scale v16i16 variable permutes to use v32i8 codegen

XOP was already doing this, and now AVX performs v32i8 variable permutes as well.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@327245 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed