Update start_process to pad process stack before pushing argv elements for performance

src/userprog/process.c

@@ -118,6 +118,10 @@ start_process (void *file_name_)
       /* TODO: Allocate an extra page for the rest of the process stack. */
     }
 
+  /* Align stack pointer to word size before pushing argv elements for
+     performance. */
+  if_.esp -= align_size * sizeof (uint8_t);
+  
   /* Push pointers to process arguments from argument linked list */
   struct list_elem *e = list_begin (&arg_list);
   struct list_elem *tail = list_tail (&arg_list);