fixup! reuse IndexReg.

Author: topperc

llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp

@@ -330,14 +330,13 @@ bool RISCVLegalizerInfo::legalizeBRJT(MachineInstr &MI,
   Register IndexReg = MI.getOperand(2).getReg();
   LLT IndexTy = MRI.getType(IndexReg);
 
-  MachineInstrBuilder Index;
   if (isPowerOf2_32(EntrySize)) {
     auto ShiftAmt = MIRBuilder.buildConstant(IndexTy, Log2_32(EntrySize));
-    Index = MIRBuilder.buildShl(IndexTy, IndexReg, ShiftAmt);
+    IndexReg = MIRBuilder.buildShl(IndexTy, IndexReg, ShiftAmt).getReg(0);
   } else
     return false;
 
-  auto Addr = MIRBuilder.buildPtrAdd(PtrTy, PtrReg, Index);
+  auto Addr = MIRBuilder.buildPtrAdd(PtrTy, PtrReg, IndexReg);
 
   MachineMemOperand *MMO = MF.getMachineMemOperand(
       MachinePointerInfo::getJumpTable(MF), MachineMemOperand::MOLoad,