static bool regionMatchesIC(S a, int offsetA, S b, int offsetB, int len) {
  ifdef eqic_lower
    ret regionMatchesIC_lower(a, offsetA, b, offsetB, len);
  endifdef
  ifndef eqic_lower
    ret a != null && a.regionMatches(true, offsetA, b, offsetB, len);
  endifndef
}