Fix a register scavenger crash when dealing with undefined subregs.
The LowerSubregs pass needs to preserve implicit def operands attached to
EXTRACT_SUBREG instructions when it replaces those instructions with copies.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107189 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed