[globalisel] Allow SrcOp to convert an APInt and render it as an immediate operand (MO.isImm() == true)

Summary:
This is tested by D61289 but has been pulled into a separate patch at
a reviewers request.

Reviewers: bogner, aditya_nandakumar, volkan, aemerson, paquette, arsenm, rovka

Reviewed By: arsenm

Subscribers: javed.absar, hiraditya, wdng, kristof.beyls, Petar.Avramovic, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61321

llvm-svn: 368063
diff --git a/llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp b/llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp
index c3c1825..61da8d7 100644
--- a/llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp
@@ -544,7 +544,7 @@
 /// SubRegCopy (To class) = COPY CopyReg:SubReg
 /// Dst = COPY SubRegCopy
 static bool selectSubregisterCopy(MachineInstr &I, MachineRegisterInfo &MRI,
-                                  const RegisterBankInfo &RBI, unsigned SrcReg,
+                                  const RegisterBankInfo &RBI, Register SrcReg,
                                   const TargetRegisterClass *From,
                                   const TargetRegisterClass *To,
                                   unsigned SubReg) {