Pre 1870 Church of Ireland parish records deposited in the Public Records Office (PRO) Dublin were destroyed by fire during the civil war in 1922. What remains pre 1870 were records not sent to Dublin by some parishes, records already published in printed form and copies or transcripts held by parishes of the records sent in. Representative Church Body (RCB) Library in Dublin now hold the bulk of what remains, both pre and post 1870, either as original records or microfilm copies. Many of the RCB microfilms are for Ulster parishes.
National Archives (NA) have a number and National Library (NL) a few of the remaining microfilm parish records available in Dublin. RCB will sell you a list of parishes, arranged county by county with dates of type of records held, baptisms, marriages, burials. If the parish you are looking for is not listed by them, then the records are probably in the parish itself or else they did not survive. If you find you are in this situation, RCB may be able to help you. Otherwise I suggest checking an Irish County Genealogy Service who may well have copied locally held records.