[RISCV] Apply a review suggestion

Author: pfusik

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -27419,21 +27419,20 @@ SDValue DAGCombiner::XformToShuffleWithZero(SDNode *N) {
         continue;
       }
 
-      APInt Bits;
-      if (auto OptBits = Elt->bitcastToAPInt())
-        Bits = *std::move(OptBits);
-      else
+      std::optional<APInt> Bits = Elt->bitcastToAPInt();
+      if (!Bits)
         return SDValue();
 
       // Extract the sub element from the constant bit mask.
       if (DAG.getDataLayout().isBigEndian())
-        Bits = Bits.extractBits(NumSubBits, (Split - SubIdx - 1) * NumSubBits);
+        *Bits =
+            Bits->extractBits(NumSubBits, (Split - SubIdx - 1) * NumSubBits);
       else
-        Bits = Bits.extractBits(NumSubBits, SubIdx * NumSubBits);
+        *Bits = Bits->extractBits(NumSubBits, SubIdx * NumSubBits);
 
-      if (Bits.isAllOnes())
+      if (Bits->isAllOnes())
         Indices.push_back(i);
-      else if (Bits == 0)
+      else if (*Bits == 0)
         Indices.push_back(i + NumSubElts);
       else
         return SDValue();