Hi Andrew, I am not saying that. My findings are : number of default optimizations in O2 = number of default optimizations in O3 < number of default optimizations in O1. This is true when we turn off all corresponding optimizations that are controllable through CLI. I tested that by myself. I can give you a reference paper arguing that. http://users.elis.ugent.be/~leeckhou/papers/cgo08.pdf Please check Section 6 in this paper. Regards. -- View this message in context: http://gcc.1065356.n5.nabble.com/Question-about-default-optimizations-tp1208211p1208792.html Sent from the gcc - Help mailing list archive at Nabble.com.