Refine the style to avoid if-else chain.

Author: tclin914

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

@@ -5768,15 +5768,14 @@ bool SelectionDAG::isKnownNeverNaN(SDValue Op, const APInt &DemandedElts,
       APInt DemandedSrcElts = DemandedElts & ~DemandedMask;
       APInt DemandedSubElts = DemandedElts.extractBits(NumSubElts, Idx);
 
-      if (!DemandedSrcElts.isZero() && !DemandedSubElts.isZero()) {
-        return isKnownNeverNaN(BaseVector, DemandedSrcElts, SNaN, Depth + 1) &&
-               isKnownNeverNaN(SubVector, DemandedSubElts, SNaN, Depth + 1);
-      }
+      bool NeverNaN = true;
       if (!DemandedSrcElts.isZero())
-        return isKnownNeverNaN(BaseVector, DemandedSrcElts, SNaN, Depth + 1);
-      if (!DemandedSubElts.isZero())
-        return isKnownNeverNaN(SubVector, DemandedSubElts, SNaN, Depth + 1);
-      return true;
+        NeverNaN &=
+            isKnownNeverNaN(BaseVector, DemandedSrcElts, SNaN, Depth + 1);
+      if (NeverNaN && !DemandedSubElts.isZero())
+        NeverNaN &=
+            isKnownNeverNaN(SubVector, DemandedSubElts, SNaN, Depth + 1);
+      return NeverNaN;
     }
     return isKnownNeverNaN(BaseVector, SNaN, Depth + 1) &&
            isKnownNeverNaN(SubVector, SNaN, Depth + 1);