[Analysis] Use a range-based for loop (NFC) (#104445)

Author: kazutakahirata

llvm/lib/Analysis/ValueTracking.cpp

@@ -6035,8 +6035,8 @@ Value *llvm::isBytewiseValue(Value *V, const DataLayout &DL) {
 
   if (isa<ConstantAggregate>(C)) {
     Value *Val = UndefInt8;
-    for (unsigned I = 0, E = C->getNumOperands(); I != E; ++I)
-      if (!(Val = Merge(Val, isBytewiseValue(C->getOperand(I), DL))))
+    for (Value *Op : C->operands())
+      if (!(Val = Merge(Val, isBytewiseValue(Op, DL))))
         return nullptr;
     return Val;
   }