+ Setting the flag 'tracing' to non-zero enables the code that
+ emits the trace bytecodes at the appropriate points. */
+
+ unsigned int tracing : 1;
+
+ /* This indicates that pointers to chars should get an added
+ tracenz bytecode to record nonzero bytes, up to a length that
+ is the value of trace_string. */
+
+ int trace_string;
+ };
+
+/* An agent_expr owning pointer. */
+typedef std::unique_ptr<agent_expr> agent_expr_up;