cc -shared -o migensim.vpi ipc.o main.o -lvpi
Undefined symbols for architecture x86_64:
  "_vpi_control", referenced from:
      _connect_calltf in main.o
      _tick_calltf in main.o
  "_vpi_get", referenced from:
      _h_write in main.o
      _h_read in main.o
  "_vpi_get_value", referenced from:
      _connect_calltf in main.o
      _h_read in main.o
  "_vpi_handle", referenced from:
      _connect_calltf in main.o
  "_vpi_handle_by_index", referenced from:
      _h_write in main.o
      _h_read in main.o
  "_vpi_handle_by_name", referenced from:
      _h_write in main.o
      _h_read in main.o
  "_vpi_iterate", referenced from:
      _connect_calltf in main.o
  "_vpi_put_value", referenced from:
      _h_write in main.o
  "_vpi_register_systf", referenced from:
      _migensim_register in main.o
  "_vpi_scan", referenced from:
      _connect_calltf in main.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [migensim.vpi] Error 1