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nemu/include/monitor/watchpoint.h

@@ -17,7 +17,7 @@ struct WP {
   bool evalulate() {
     auto new_value = evaluate_expr(expr);
     std::swap(new_value, curr_value);
-    return new_value != curr_value;
+    return new_value != curr_value && curr_value != 0;
   }
   WP(std::string e, int id) : expr(e), id(id) {
     evalulate(); // initial expr value.