[X86] Add custom promotion of v2i8/v2i16 fp_to_sint to avoid over promotion to v2i64 which would force scalarization.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@346259 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed