code: public final int getConstantIndex(double constant)
      {
          for (ConstantInfo ci : listConstantInfo(ConstantDouble.class))
          {
              ConstantDouble ic = (ConstantDouble) ci;
              if (Double.compare(constant, ic.getConstant()) == 0)
              {
                  return constantPoolIndexMap.get(ci);
              }
          }
          return -1;
      }
docs: Returns the constant map index to constant
  @param constant
  @return