List<Instr> codegen(List<Stm> body) {
List<Instr> l = null, t = null;
for (; body != null; body = body.tail) {
munchStm(body.head);
if (l == null) l = ilist;
else t.tail = ilist;
t = last;
ilist = last = null;
}
return l;
}
private void emit(Instr inst) {
if (last != null) last = last.tail = new List<Instr>(inst, null);
else last = ilist = new List<Instr>(inst, null);
}