message: Avoid costly `show(cfg)`
  Summary: Unless tracing the result is not used. So make it conditional (assuming that the trace level does not change).
diff: @@ -935,7 +935,8 @@ MethodInfo instrument_basic_blocks(IRCode& code,
  code.build_cfg(/*editable*/ true);
  ControlFlowGraph& cfg = code.cfg();
  - const std::string& before_cfg = show(cfg);
  + std::string before_cfg =
  + traceEnabled(INSTRUMENT, 7) ? show(cfg) : std::string("");
  // Step 1: Get sorted basic blocks to instrument with their information.
  //
  