[X86] In getScalarMaskingNode, replace scalar_to_vector with a bitcast to v8i1 and an extract_subvector to convert i8 to v1i1.

The bitcast can be nicely merged with any i8 loads that exist for argument passing in 32 mode for example.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@347380 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed