/**
  * Generate code for the case where we actually want a boolean value (true or false) computed onto
  * the stack, eg for assignment to a boolean variable.
  *
  * @param output the code emitter (basically an abstraction for producing the .class file).
  */
 public void codegen(CLEmitter output) {
   String elseLabel = output.createLabel();
   String endIfLabel = output.createLabel();
   this.codegen(output, elseLabel, false);
   output.addNoArgInstruction(ICONST_1); // true
   output.addBranchInstruction(GOTO, endIfLabel);
   output.addLabel(elseLabel);
   output.addNoArgInstruction(ICONST_0); // false
   output.addLabel(endIfLabel);
 }