Something very strange is going on with the output registers in this
target. Its ISelLowering code is inserting dangling CopyToReg nodes,
hoping that those physregs won't get clobbered before the RETURN.
This patch adds the output registers as implicit uses on RETURN
instructions in the custom emission pass. I'd much prefer to have those
CopyToReg nodes glued to the RETURNs, but I don't see how.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174400 91177308-0d34-0410-b5e6-96231b3b80d8
a499d2bcef