Can anybody tell me how it bypass timing simulation when choosing the -gpgpu_ptx_sim_mode 1 to use pure func simulation mode?

[underwerd]

I know it can bypass timing simulation when choose func simulation mode,because I haved ran two situations in -gpgpu_ptx_sim_mode 1 and -gpgpu_ptx_sim_mode 0,the time of running in mode 1 is less than mode 0.
But when I try to find how in the source code,I meet some difficulties.
In gpgpu_entrypoint.cc,void *gpgpu_sim_thread_concurrent(void *ctx_ptr),it has code that

      // functional simulation
      if (ctx->the_gpgpusim->g_the_gpu->is_functional_sim()) {
        kernel_info_t *kernel =
            ctx->the_gpgpusim->g_the_gpu->get_functional_kernel();
        assert(kernel);
        ctx->the_gpgpusim->gpgpu_ctx->func_sim->gpgpu_cuda_ptx_sim_main_func(
            *kernel);
        ctx->the_gpgpusim->g_the_gpu->finish_functional_sim(kernel);
      }
      if (ctx->the_gpgpusim->g_the_gpu->active()) {
        ctx->the_gpgpusim->g_the_gpu->cycle();
        sim_cycles = true;
        ctx->the_gpgpusim->g_the_gpu->deadlock_check();
      } else {
        if (ctx->the_gpgpusim->g_the_gpu->cycle_insn_cta_max_hit()) {
          printf("cycle_insn_cta_max_hit()\n");
          fflush(stdout);
          ctx->the_gpgpusim->g_stream_manager->stop_all_running_kernels();
          ctx->the_gpgpusim->g_sim_done = true;
          ctx->the_gpgpusim->break_limit = true;
        }
      }

When I debug the code,I fine when I choose sim mode 1,ctx->the_gpgpusim->g_the_gpu->active(),but I can't find when or how active() if false ,it was set when init or other time?
And,I find when I choose sim mode 1,ctx->the_gpgpusim->g_the_gpu->cycle_insn_cta_max_hit() is also false, which means the while is not break because ctx->the_gpgpusim->g_sim_done = true; in ctx->the_gpgpusim->g_the_gpu->cycle_insn_cta_max_hit() , so how the while break ?