Reorder fields on OperandStack

lib/fizzy/stack.hpp

@@ -62,17 +62,21 @@ class OperandStack
     /// The size of the pre-allocated internal storage: 128 bytes.
     static constexpr auto small_storage_size = 128 / sizeof(Value);
 
-    /// The pointer to the top item, or below the stack bottom if stack is empty.
+    /// The pointer to the top item of the operand stack,
+    /// or below the stack bottom if stack is empty.
     ///
-    /// This pointer always alias m_storage, but it is kept as the first field
+    /// This pointer always alias m_locals, but it is kept as the first field
     /// because it is accessed the most. Therefore, it must be initialized
-    /// in the constructor after the m_storage.
+    /// in the constructor after the m_locals.
     Value* m_top;
 
-    Value* m_bottom;
-
+    /// The pointer to the beginning of the locals array.
+    /// This always points to one of the storages.
     Value* m_locals;
 
+    /// The pointer to the bottom of the operand stack.
+    Value* m_bottom;
+
     /// The pre-allocated internal storage.
     Value m_small_storage[small_storage_size];
 
@@ -97,18 +101,16 @@ class OperandStack
         const auto num_args = args.size();
         const auto storage_size_required = num_args + num_local_variables + max_stack_height;
 
-        Value* storage;
         if (storage_size_required <= small_storage_size)
         {
-            storage = &m_small_storage[0];
+            m_locals = &m_small_storage[0];
         }
         else
         {
             m_large_storage = std::make_unique<Value[]>(storage_size_required);
-            storage = &m_large_storage[0];
+            m_locals = &m_large_storage[0];
         }
 
-        m_locals = storage;
         m_bottom = m_locals + num_args + num_local_variables;
         m_top = m_bottom - 1;