27    std::vector<DebugHook> hooks;
 
   32    IR::ToplevelBlock *toplevel = 
nullptr;
 
   34    void addDebugHook(DebugHook hook) { hooks.push_back(hook); }
 
   36    IR::ToplevelBlock *process(
const IR::P4Program *&program) {
 
   37        addDebugHooks(hooks, 
true);
 
   38        program = program->apply(*
this);