private ClassWriter createCompiledCtor(String namePath, String shortPath, String sup) {
ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);
cw.visit(RubyInstanceConfig.JAVA_VERSION, ACC_PUBLIC + ACC_SUPER, namePath, null, sup, null);
cw.visitSource(shortPath, null);
SkinnyMethodAdapter mv = new SkinnyMethodAdapter(cw, ACC_PUBLIC, "<init>", "()V", null, null);
mv.visitCode();
mv.line(-1);
mv.aload(0);
mv.visitMethodInsn(INVOKESPECIAL, sup, "<init>", "()V");
mv.visitLineNumber(-1, new Label());
mv.voidreturn();