code: public Location getLocationAtEntry() {
          InstructionHandle handle = getEntry().getFirstInstruction();
          assert handle != null;
          return new Location(handle, getEntry());
      }
docs: Get the Location representing the entry to the CFG. Note that this is a
  "fake" Location, and shouldn't be relied on to yield source line
  information.
  
  @return Location at entry to CFG