public RegisterSpec withOffset(int delta) {
    if (delta == 0) {
      return this;
    }

    return withReg(reg + delta);
  }
Returns an instance that is identical to this one, except that the register number is offset by
the given amount.

@param delta the amount to offset the register number by
@return {@code non-null;} an appropriately-constructed instance
android/android_framework/dex-maker/src/main/java/com/android/dx/rop/code/RegisterSpec.java