Be more strict about subreg-to-subreg copies in CoalescerPair.

Also keep track of the original DstREg before subregister adjustments.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106753 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed