/**
     * Write the Java code required for error checking and calling the emit method represented by a
     * singleton EmitterSet. A singleton EmiiterSet will typically be the result of a series of
     * splits of bigger sets, where the splits represent emitted queries of operand types and sizes.
     * (See emitSet) However, there may be cases when some operand has only one possible options, so
     * the splitting will not have generated any tests for it. In this case, we will emit assertions
     * that guarantee the operand is of the expected type. Note that the answers to queries
     * alrrready performed by splitting are known to be fine, so no additional error checking is
     * needed for cases they cover.
     *
     * @see #emitSet
     * @param opcode the IA32 opcode to generate
     * @param testsPerformed the set of queries already performed by splitting.
     * @param level level of indentation for prett printing
     */
    private void emitSingleton(String opcode, boolean[][] testsPerformed, int level) {
      EmitterDescriptor ed = (EmitterDescriptor) emitters.iterator().next();

      ArgumentType[] args = ed.getArgs();
      int count = ed.getCount();
      for (int i = 0; i < count; i++)
        if (!testsPerformed[i][args[i].ordinal()]) emitVerify(i, args[i], level);

      ArgumentType size = ed.getSize();
      if (size != null) {
        boolean needed = true;

        for (int i = 0; i < count; i++) if (testsPerformed[i][size.ordinal()]) needed = false;

        if (needed) emitVerify(0, size, level);

        if (size == ArgumentType.Byte)
          for (int i = 0; i < count; i++)
            if (args[i] == ArgumentType.GPRegister)
              if (currentOpcode.indexOf("MOVZX") == -1 && currentOpcode.indexOf("MOVSX") == -1) {
                emitTab(level);
                emit("if (VM.VerifyAssertions) opt_assert(");
                emitArgs(i, ArgumentType.GPRegister);
                emit(".isValidAs8bitRegister());\n");
              }
      }

      emitEmitCall(opcode, args, count, level, ed.getSize());
    }
    /**
     * This method uses a SplitRecord as the criertion to partition the given EmitterSet into two
     * subsets.
     *
     * @param split the plit record dicatating how to split
     */
    private EmitterSet[] makeSplit(SplitRecord split) {
      int arg = split.argument;
      ArgumentType test = split.test;
      EmitterSet yes = new EmitterSet();
      EmitterSet no = new EmitterSet();
      Iterator<EmitterDescriptor> i = emitters.iterator();
      while (i.hasNext()) {
        EmitterDescriptor ed = (EmitterDescriptor) i.next();
        if (ed.argMatchesEncoding(arg, test)) {
          yes.add(ed);
        } else {
          no.add(ed);
        }
      }

      return new EmitterSet[] {yes, no};
    }