Dublin's Aviva Stadium and the Ricoh Arena in Coventry, as well as three French stadiums - Saint-Etienne's Stade Geoffroy Guichard, the Allianz Riviera Stadium in Nice and Stade Chaban-Delmas in Bordeaux - have been chosen as the venues which are in line to host this season's Champions Cup semi-finals on 21 and 22 April.