[RISCV] Use if init statement to reduce scope of variable. NFC

Author: topperc

llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp

@@ -2978,8 +2978,8 @@ bool RISCVDAGToDAGISel::selectSHXADDOp(SDValue N, unsigned ShAmt,
   if (N.getOpcode() == ISD::AND && isa<ConstantSDNode>(N.getOperand(1))) {
     SDValue N0 = N.getOperand(0);
 
-    bool LeftShift = N0.getOpcode() == ISD::SHL;
-    if ((LeftShift || N0.getOpcode() == ISD::SRL) &&
+    if (bool LeftShift = N0.getOpcode() == ISD::SHL;
+        (LeftShift || N0.getOpcode() == ISD::SRL) &&
         isa<ConstantSDNode>(N0.getOperand(1))) {
       uint64_t Mask = N.getConstantOperandVal(1);
       unsigned C2 = N0.getConstantOperandVal(1);
@@ -3020,11 +3020,9 @@ bool RISCVDAGToDAGISel::selectSHXADDOp(SDValue N, unsigned ShAmt,
         }
       }
     }
-  }
-
-  bool LeftShift = N.getOpcode() == ISD::SHL;
-  if ((LeftShift || N.getOpcode() == ISD::SRL) &&
-      isa<ConstantSDNode>(N.getOperand(1))) {
+  } else if (bool LeftShift = N.getOpcode() == ISD::SHL;
+             (LeftShift || N.getOpcode() == ISD::SRL) &&
+             isa<ConstantSDNode>(N.getOperand(1))) {
     SDValue N0 = N.getOperand(0);
     if (N0.getOpcode() == ISD::AND && N0.hasOneUse() &&
         isa<ConstantSDNode>(N0.getOperand(1))) {