diff --git a/reference_model/src/ops/control_flow.cc b/reference_model/src/ops/control_flow.cc
index 827e01f..1a6a63a 100644
--- a/reference_model/src/ops/control_flow.cc
+++ b/reference_model/src/ops/control_flow.cc
@@ -93,6 +93,8 @@
             return 1;
         }
 
+        tensor->setIsValid();
+
         // Push ready consumers to the next node list
         for (auto gn : tensor->getConsumers())
         {
@@ -292,8 +294,7 @@
 int OpWhileLoop::eval()
 {
 
-    TosaReference::Tensor0<bool> cond_output_ctensor(std::string("cond_output"), DType_BOOL,
-                                                     std::vector<int32_t>({}));
+    TosaReference::Tensor0<bool> cond_output_ctensor(std::string("cond_output"), DType_BOOL, std::vector<int32_t>({}));
 
     cond_output_ctensor.allocate();
     std::vector<TosaReference::Tensor*> cond_block_outputs;
diff --git a/reference_model/src/ops/data_nodes.cc b/reference_model/src/ops/data_nodes.cc
index 883cd1b..baae019 100644
--- a/reference_model/src/ops/data_nodes.cc
+++ b/reference_model/src/ops/data_nodes.cc
@@ -42,29 +42,6 @@
     return GraphNode::eval();
 }
 
-OpPlaceholder::OpPlaceholder(uint64_t id_)
-    : GraphNode(Op_PLACEHOLDER, id_)
-{
-    setRequiredOperands(0, 1);
-}
-
-OpPlaceholder::~OpPlaceholder()
-{}
-
-int OpPlaceholder::checkTensorAttributes()
-{
-    if (validateRequiredOperands())
-        return 1;
-
-    return 0;
-}
-
-int OpPlaceholder::eval()
-{
-    // Evaluation is trivial for placeholders
-    return GraphNode::eval();
-}
-
 template <int Rank, DType Dtype>
 OpIdentity<Rank, Dtype>::OpIdentity(TosaAttributeBase* attribute_, TosaQuantInfoBase* qinfo_, uint64_t id_)
     : GraphNode(Op_IDENTITY, id_)
@@ -107,64 +84,11 @@
     return GraphNode::eval();
 }
 
-template <int Rank, DType Dtype>
-OpIdentityN<Rank, Dtype>::OpIdentityN(TosaAttributeBase* attribute_, TosaQuantInfoBase* qinfo_, uint64_t id_)
-    : GraphNode(Op_IDENTITYN, id_)
-{
-    setRequiredRank(0, 6);
-}
-
-template <int Rank, DType Dtype>
-OpIdentityN<Rank, Dtype>::~OpIdentityN()
-{}
-
-template <int Rank, DType Dtype>
-int OpIdentityN<Rank, Dtype>::checkTensorAttributes()
-{
-
-    if (inputs.size() != outputs.size())
-    {
-        printNodeValidationError("Input and output tensor list lengths are not equal");
-        return 1;
-    }
-
-    for (size_t i = 0; i < inputs.size(); i++)
-    {
-        ins.push_back(dynamic_cast<TosaReference::TensorTemplate<TIn>*>(inputs[i]));
-        outs.push_back(dynamic_cast<TosaReference::TensorTemplate<TOut>*>(outputs[i]));
-
-        if (ins[i]->matchRankTypeShape(*outs[i]))
-        {
-            printNodeValidationError("Input and output tensor rank, type, or shape do not match");
-            return 1;
-        }
-    }
-
-    return 0;
-}
-
-template <int Rank, DType Dtype>
-int OpIdentityN<Rank, Dtype>::eval()
-{
-    for (size_t i = 0; i < ins.size(); i++)
-    {
-        outs[i]->getTensor() = ins[i]->getTensor();
-    }
-
-    return GraphNode::eval();
-}
-
 // template explicit instantiation
-// note OpConst and OpPlaceholder are not templated
+// note OpConst is not templated
 
 DEF_INSTANTIATE_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentity, FLOAT);
 DEF_INSTANTIATE_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentity, INT8);
 DEF_INSTANTIATE_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentity, INT16);
 DEF_INSTANTIATE_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentity, INT32);
 DEF_INSTANTIATE_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentity, BOOL);
-
-DEF_INSTANTIATE_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentityN, FLOAT);
-DEF_INSTANTIATE_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentityN, INT8);
-DEF_INSTANTIATE_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentityN, INT16);
-DEF_INSTANTIATE_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentityN, INT32);
-DEF_INSTANTIATE_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentityN, BOOL);
diff --git a/reference_model/src/ops/data_nodes.h b/reference_model/src/ops/data_nodes.h
index bec4669..a02d441 100644
--- a/reference_model/src/ops/data_nodes.h
+++ b/reference_model/src/ops/data_nodes.h
@@ -31,16 +31,6 @@
     virtual int eval();
 };
 
-class OpPlaceholder : public GraphNode
-{
-public:
-    OpPlaceholder(uint64_t id_);
-    virtual ~OpPlaceholder();
-
-    virtual int checkTensorAttributes();
-    virtual int eval();
-};
-
 template <int Rank, DType Dtype>
 class OpIdentity : public GraphNode
 {
@@ -61,26 +51,6 @@
     TosaReference::TensorTemplate<TOut>* out;
 };
 
-template <int Rank, DType Dtype>
-class OpIdentityN : public GraphNode
-{
-public:
-    OpIdentityN(TosaAttributeBase* attribute_, TosaQuantInfoBase* qinfo_, uint64_t id_);
-    virtual ~OpIdentityN();
-
-    virtual int checkTensorAttributes();
-    virtual int eval();
-
-    using InEigenType  = typename GetEigenType<Dtype>::type;
-    using OutEigenType = typename GetEigenType<Dtype>::type;
-    using TIn          = Eigen::Tensor<InEigenType, Rank>;
-    using TOut         = Eigen::Tensor<OutEigenType, Rank>;
-
-protected:
-    std::vector<TosaReference::TensorTemplate<TIn>*> ins;
-    std::vector<TosaReference::TensorTemplate<TOut>*> outs;
-};
-
 };    // namespace TosaReference
 
 #endif
diff --git a/reference_model/src/ops/ewise_binary.cc b/reference_model/src/ops/ewise_binary.cc
index fc587f1..76cebeb 100644
--- a/reference_model/src/ops/ewise_binary.cc
+++ b/reference_model/src/ops/ewise_binary.cc
@@ -298,6 +298,27 @@
 }
 
 template <int Rank, DType Dtype>
+int OpDiv<Rank, Dtype>::register_fcn()
+{
+    switch (InDtype)
+    {
+        case DType_INT32:
+            this->fcn = [this](InEigenType a, InEigenType b) -> OutEigenType {
+                ASSERT_MSG_NODE(b != 0, "OpDiv: divisor must be non-zero value");
+                int64_t res_in_64     = static_cast<int64_t>(a) / b;
+                int64_t i32_max_in_64 = static_cast<int64_t>(std::numeric_limits<InEigenType>::max());
+                ASSERT_MSG_NODE(a <= i32_max_in_64, "OpDiv: result not in i32 range");
+                return static_cast<InEigenType>(res_in_64);
+            };
+            break;
+        default:
+            FATAL_ERROR_NODE("unsupported DType %s", EnumNamesDType()[InDtype]);
+    }
+
+    return 0;
+}
+
+template <int Rank, DType Dtype>
 int OpLogicalAnd<Rank, Dtype>::register_fcn()
 {
     switch (Dtype)
@@ -579,6 +600,8 @@
 DEF_INSTANTIATE_RANK0_6_ONE_RANK_ONE_TYPE(OpBitwiseXor, INT16);
 DEF_INSTANTIATE_RANK0_6_ONE_RANK_ONE_TYPE(OpBitwiseXor, INT32);
 
+DEF_INSTANTIATE_RANK0_6_ONE_RANK_ONE_TYPE(OpDiv, INT32);
+
 DEF_INSTANTIATE_RANK0_6_ONE_RANK_ONE_TYPE(OpLogicalAnd, BOOL);
 
 DEF_INSTANTIATE_RANK0_6_ONE_RANK_ONE_TYPE(OpLogicalLeftShift, INT8);
diff --git a/reference_model/src/ops/ewise_binary.h b/reference_model/src/ops/ewise_binary.h
index 5bc5630..6b9c98d 100644
--- a/reference_model/src/ops/ewise_binary.h
+++ b/reference_model/src/ops/ewise_binary.h
@@ -125,6 +125,7 @@
 DEF_TEMPLATE_BINARY_OP_DEFAULT(BitwiseAnd, BITWISE_AND)
 DEF_TEMPLATE_BINARY_OP_DEFAULT(BitwiseOr, BITWISE_OR)
 DEF_TEMPLATE_BINARY_OP_DEFAULT(BitwiseXor, BITWISE_XOR)
+DEF_TEMPLATE_BINARY_OP_DEFAULT(Div, DIV)
 DEF_TEMPLATE_BINARY_OP_DEFAULT(LogicalAnd, LOGICAL_AND)
 DEF_TEMPLATE_BINARY_OP_DEFAULT(LogicalLeftShift, LOGICAL_LEFT_SHIFT)
 DEF_TEMPLATE_BINARY_OP_DEFAULT(LogicalRightShift, LOGICAL_RIGHT_SHIFT)
diff --git a/reference_model/src/ops/op_factory.cc b/reference_model/src/ops/op_factory.cc
index b326c63..440d624 100644
--- a/reference_model/src/ops/op_factory.cc
+++ b/reference_model/src/ops/op_factory.cc
@@ -134,6 +134,9 @@
             DEF_FACTORY_RANK0_6_ONE_RANK_ONE_TYPE(OpBitwiseXor, INT16);
             DEF_FACTORY_RANK0_6_ONE_RANK_ONE_TYPE(OpBitwiseXor, INT32);
             break;
+        case Op_DIV:
+            DEF_FACTORY_RANK0_6_ONE_RANK_ONE_TYPE(OpDiv, INT32);
+            break;
         case Op_LOGICAL_AND:
             DEF_FACTORY_RANK0_6_ONE_RANK_ONE_TYPE(OpLogicalAnd, BOOL);
             break;
@@ -346,8 +349,6 @@
         // data_nodes
         case Op_CONST:
             return new OpConst(id);
-        case Op_PLACEHOLDER:
-            return new OpPlaceholder(id);
         case Op_IDENTITY:
             DEF_FACTORY_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentity, FLOAT);
             DEF_FACTORY_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentity, INT32);
@@ -355,13 +356,6 @@
             DEF_FACTORY_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentity, INT16);
             DEF_FACTORY_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentity, BOOL);
             break;
-        case Op_IDENTITYN:
-            DEF_FACTORY_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentityN, FLOAT);
-            DEF_FACTORY_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentityN, INT32);
-            DEF_FACTORY_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentityN, INT8);
-            DEF_FACTORY_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentityN, INT16);
-            DEF_FACTORY_RANK0_6_ONE_RANK_ONE_TYPE(OpIdentityN, BOOL);
-            break;
 
         // type_conversion
         case Op_CAST:
diff --git a/reference_model/src/quant_util.h b/reference_model/src/quant_util.h
index f07dd10..c595869 100644
--- a/reference_model/src/quant_util.h
+++ b/reference_model/src/quant_util.h
@@ -65,8 +65,8 @@
     static int32_t apply_scale_16(int64_t value, int16_t multiplier, int32_t shift)
     {
         ASSERT_MSG(multiplier >= 0, "apply_scale_16() error: multiplier should >= 0 but is %d", multiplier);
-        ASSERT_MSG(value >= -(static_cast<int64_t>(1) << 47) && value < (static_cast<int64_t>(1) << 47),
-                   "apply_scale_16() error: value should be within [-(1^47), 1^47]");
+        ASSERT_MSG(shift >= 2 && shift <= 62, "apply_scale_16() error: shift should be within [2, 62] but is %d",
+                   shift);
         int64_t round  = 1L << (shift - 1);
         int64_t result = value * (int64_t)multiplier + round;
         result         = result >> shift;
diff --git a/reference_model/src/subgraph_traverser.cc b/reference_model/src/subgraph_traverser.cc
index 5096ffa..1995b5c 100644
--- a/reference_model/src/subgraph_traverser.cc
+++ b/reference_model/src/subgraph_traverser.cc
@@ -499,7 +499,6 @@
     // For each node, read this list, link up the tensors with their inputs/outputs
     for (GraphNode* currNode : nodes)
     {
-
         // Link inputs/consuming nodes
         for (std::string& name : currNode->getInputNames())
         {
@@ -566,36 +565,18 @@
     for (TosaReference::Tensor* currTensor : tensors)
     {
 
-        if (!currTensor->getProducer() && currTensor->getConsumers().empty())
+        // It's okay for block input tensor not being consumed by operators.
+        // This is common in control flow op execution.
+        if (!currTensor->getIsSubgraphInput())
         {
-            WARNING("Graph inconsistency: TosaReference::Tensor %s has no producers or consumers\n",
-                    currTensor->getName().c_str());
-            return 1;
-        }
-
-        if (currTensor->getIsSubgraphInput())
-        {
-            if (currTensor->getProducer() && currTensor->getProducer()->getOp() != Op_PLACEHOLDER)
+            if (!currTensor->getProducer() && currTensor->getConsumers().empty())
             {
-                WARNING("Graph inconsistency: TosaReference::Tensor %s is a subgraph input and has a producer\n",
+                WARNING("Graph inconsistency: TosaReference::Tensor %s has no producers or consumers\n",
                         currTensor->getName().c_str());
                 return 1;
             }
         }
 
-        // comment this check out as this is possible when graph have multiple output
-        // for example:
-        //   %0 = add(%arg0, %arg1)
-        //   %1 = mul(%arg0, %0)
-        //   yields(%0, %1)
-        //if (currTensor->getIsSubgraphOutput()) {
-        //    if (!currTensor->getConsumers().empty()) {
-        //        WARNING ("Graph inconsistency: TosaReference::Tensor %s is a subgraph output and has a consumer\n",
-        //                     currTensor->getName().c_str());
-        //        return 1;
-        //    }
-        //}
-
         if (g_func_config.tosa_profile == 0)
         {
             DType dtype = currTensor->getDtype();