Fix build errors introduced by r349712 on aarch64 bots.

llvm-svn: 349723
diff --git a/llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp b/llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp
index cbb2e5c..5eb589b 100644
--- a/llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp
@@ -1625,10 +1625,9 @@
                                 .addImm(0)
                                 .addUse(I.getOperand(2).getReg())
                                 .addImm(AArch64::sub_32);
-  unsigned BFMDef = MRI.createVirtualRegister(DstRC);
   MachineInstr &BFM =
       *BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(AArch64::BFMXri))
-           .addDef(BFMDef)
+           .addDef(I.getOperand(0).getReg())
            .addUse(SubToRegDef)
            .addUse(SubToRegDef2)
            .addImm(32)