*
* @return The length of os at the start of the method code.
*/
public int emitHeader() {
final VmMethodCode code = new VmMethodCode();
final Label startLabel = helper.genLabel("$$start");
codeObject = os.startObject(entryPoints.getVmMethodCodeClass());
os.setObjectRef(code);
cm.setCodeStart(os.setObjectRef(startLabel));
final int rc = os.getLength();