diff --git a/src/interpreter/ByteCodeInterpreter.cpp b/src/interpreter/ByteCodeInterpreter.cpp
index a2cf71f70..c15d28e87 100644
--- a/src/interpreter/ByteCodeInterpreter.cpp
+++ b/src/interpreter/ByteCodeInterpreter.cpp
@@ -103,7 +103,7 @@ OpcodeTable::OpcodeTable()
 class InterpreterSlowPath {
 public:
     static Value loadByName(ExecutionState& state, LexicalEnvironment* env, const AtomicString& name, bool throwException = true);
-    static EnvironmentRecord* getBindedEnvironmentRecordByName(ExecutionState& state, LexicalEnvironment* env, const AtomicString& name, Value& bindedValue, bool throwException = true);
+    static EnvironmentRecord* getBindedEnvironmentRecordByName(ExecutionState& state, LexicalEnvironment* env, const AtomicString& name, Value& bindedValue);
     static void storeByName(ExecutionState& state, LexicalEnvironment* env, const AtomicString& name, const Value& value);
     static void initializeByName(ExecutionState& state, LexicalEnvironment* env, const AtomicString& name, bool isLexicallyDeclaredName, const Value& value);
     static void resolveNameAddress(ExecutionState& state, ResolveNameAddress* code, Value* registerFile);
@@ -1682,7 +1682,7 @@ Value Interpreter::interpret(ExecutionState* state, ByteCodeBlock* byteCodeBlock
     return Value();
 }
 
-NEVER_INLINE EnvironmentRecord* InterpreterSlowPath::getBindedEnvironmentRecordByName(ExecutionState& state, LexicalEnvironment* env, const AtomicString& name, Value& bindedValue, bool throwException)
+NEVER_INLINE EnvironmentRecord* InterpreterSlowPath::getBindedEnvironmentRecordByName(ExecutionState& state, LexicalEnvironment* env, const AtomicString& name, Value& bindedValue)
 {
     while (env) {
         EnvironmentRecord::GetBindingValueResult result = env->record()->getBindingValue(state, name);
@@ -1693,9 +1693,7 @@ NEVER_INLINE EnvironmentRecord* InterpreterSlowPath::getBindedEnvironmentRecordB
         env = env->outerEnvironment();
     }
 
-    if (throwException)
-        ErrorObject::throwBuiltinError(state, ErrorCode::ReferenceError, name.string(), false, String::emptyString, ErrorObject::Messages::IsNotDefined);
-
+    ErrorObject::throwBuiltinError(state, ErrorCode::ReferenceError, name.string(), false, String::emptyString, ErrorObject::Messages::IsNotDefined);
     return NULL;
 }
 
@@ -3675,9 +3673,7 @@ NEVER_INLINE void InterpreterSlowPath::callFunctionComplexCase(ExecutionState& s
         Object* receiverObj = NULL;
         Value callee;
         EnvironmentRecord* bindedRecord = getBindedEnvironmentRecordByName(state, state.lexicalEnvironment(), calleeName, callee);
-        if (!bindedRecord) {
-            callee = Value();
-        }
+        ASSERT(!!bindedRecord);
 
         if (bindedRecord && bindedRecord->isObjectEnvironmentRecord()) {
             receiverObj = bindedRecord->asObjectEnvironmentRecord()->bindingObject();
diff --git a/src/runtime/EnvironmentRecord.cpp b/src/runtime/EnvironmentRecord.cpp
index 453c427e6..e1c014ba2 100644
--- a/src/runtime/EnvironmentRecord.cpp
+++ b/src/runtime/EnvironmentRecord.cpp
@@ -536,16 +536,6 @@ EnvironmentRecord::GetBindingValueResult ModuleEnvironmentRecord::getBindingValu
     return GetBindingValueResult();
 }
 
-Value ModuleEnvironmentRecord::getBindingValue(ExecutionState& state, const size_t i)
-{
-    if (m_moduleBindings[i].m_targetRecord) {
-        return m_moduleBindings[i].m_targetRecord->getBindingValue(state, m_moduleBindings[i].m_targetBindingName).m_value;
-    } else {
-        readCheck(state, i);
-        return m_moduleBindings[i].m_value;
-    }
-}
-
 void ModuleEnvironmentRecord::setHeapValueByIndex(ExecutionState& state, const size_t idx, const Value& v)
 {
     writeCheck(state, idx);
diff --git a/src/runtime/EnvironmentRecord.h b/src/runtime/EnvironmentRecord.h
index 582763dad..312c0c212 100644
--- a/src/runtime/EnvironmentRecord.h
+++ b/src/runtime/EnvironmentRecord.h
@@ -125,11 +125,6 @@ class EnvironmentRecord : public gc {
         return GetBindingValueResult();
     }
 
-    virtual Value getBindingValue(ExecutionState& state, const size_t idx)
-    {
-        RELEASE_ASSERT_NOT_REACHED();
-    }
-
     virtual bool deleteBinding(ExecutionState& state, const AtomicString& name)
     {
         RELEASE_ASSERT_NOT_REACHED();
@@ -1230,7 +1225,6 @@ class ModuleEnvironmentRecord : public DeclarativeEnvironmentRecord {
     virtual void setMutableBindingByIndex(ExecutionState& state, const size_t i, const Value& v) override;
     virtual void initializeBindingByIndex(ExecutionState& state, const size_t idx, const Value& v) override;
     virtual GetBindingValueResult getBindingValue(ExecutionState& state, const AtomicString& name) override;
-    virtual Value getBindingValue(ExecutionState& state, const size_t i) override;
     virtual void setHeapValueByIndex(ExecutionState& state, const size_t idx, const Value& v) override;
     virtual Value getHeapValueByIndex(ExecutionState& state, const size_t idx) override;
     Script* script()
diff --git a/src/runtime/ExecutionState.h b/src/runtime/ExecutionState.h
index 431ba0236..c821c9bd9 100644
--- a/src/runtime/ExecutionState.h
+++ b/src/runtime/ExecutionState.h
@@ -40,19 +40,19 @@ class NativeFunctionObject;
 typedef Vector<ControlFlowRecord*, GCUtil::gc_malloc_allocator<ControlFlowRecord*>> ControlFlowRecordVector;
 
 struct ExecutionStateRareData : public gc {
-    ControlFlowRecordVector* m_controlFlowRecord;
-    ExecutionState* m_parent;
     CodeBlock* m_codeBlock;
+    ControlFlowRecordVector* m_controlFlowRecord;
     ExecutionPauser* m_pauseSource;
+    ExecutionState* m_parent;
     size_t m_programCounterWhenItStoppedByYield;
 
     ExecutionStateRareData()
+        : m_codeBlock(nullptr)
+        , m_controlFlowRecord(nullptr)
+        , m_pauseSource(nullptr)
+        , m_parent(nullptr)
+        , m_programCounterWhenItStoppedByYield(SIZE_MAX)
     {
-        m_codeBlock = nullptr;
-        m_controlFlowRecord = nullptr;
-        m_pauseSource = nullptr;
-        m_parent = nullptr;
-        m_programCounterWhenItStoppedByYield = SIZE_MAX;
     }
 };
 
diff --git a/src/runtime/GlobalObject.cpp b/src/runtime/GlobalObject.cpp
index b42ca90e1..55c7775e0 100644
--- a/src/runtime/GlobalObject.cpp
+++ b/src/runtime/GlobalObject.cpp
@@ -847,7 +847,7 @@ static Value builtinArrayToString(ExecutionState& state, Value thisValue, size_t
     return Object::call(state, toString, thisObject, 0, nullptr);
 }
 
-Value builtinGenericIteratorNext(ExecutionState& state, Value thisValue, size_t argc, Value* argv, Optional<Object*> newTarget)
+static Value builtinGenericIteratorNext(ExecutionState& state, Value thisValue, size_t argc, Value* argv, Optional<Object*> newTarget)
 {
     if (!thisValue.isObject() || !thisValue.asObject()->isGenericIteratorObject()) {
         ErrorObject::throwBuiltinError(state, ErrorCode::TypeError, String::fromASCII("Iterator"), true, state.context()->staticStrings().next.string(), ErrorObject::Messages::GlobalObject_CalledOnIncompatibleReceiver);
diff --git a/src/runtime/SandBox.cpp b/src/runtime/SandBox.cpp
index b926972c3..20df75899 100644
--- a/src/runtime/SandBox.cpp
+++ b/src/runtime/SandBox.cpp
@@ -289,7 +289,7 @@ bool SandBox::createStackTrace(StackTraceDataVector& stackTraceDataVector, Execu
     return false;
 }
 
-void SandBox::throwException(ExecutionState& state, Value exception)
+void SandBox::throwException(ExecutionState& state, const Value& exception)
 {
     m_stackTraceDataVector.clear();
     createStackTrace(m_stackTraceDataVector, state);
diff --git a/src/runtime/SandBox.h b/src/runtime/SandBox.h
index 5eb1bdcf6..392abffb3 100644
--- a/src/runtime/SandBox.h
+++ b/src/runtime/SandBox.h
@@ -85,7 +85,7 @@ class SandBox : public gc {
 
     static bool createStackTrace(StackTraceDataVector& stackTraceDataVector, ExecutionState& state, bool stopAtPause = false);
 
-    void throwException(ExecutionState& state, Value exception);
+    void throwException(ExecutionState& state, const Value& exception);
     void rethrowPreviouslyCaughtException(ExecutionState& state, Value exception, const StackTraceDataVector& stackTraceDataVector);
 
     StackTraceDataVector& stackTraceDataVector()