FIRST_STRING_P
(FIRST_STRING_P (ptr) ? (ptr) - string1 : (ptr) - string2 + size1)
boolean same_str_p = (FIRST_STRING_P (match_end)
dend2 = ((FIRST_STRING_P (regstart[regno])
== FIRST_STRING_P (regend[regno]))
if (FIRST_STRING_P (where))