[X86] Redefine KUNPCK instructions to take a narrower source register class than destination register class. Remove copies from the isel output pattern.

There's no reason for the inputs to be the destination register class. This just
forces an unnecessary copy in the output patterns.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@358362 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed