> > > Is -ftree-vectorize enabled by default at any -On? > > No, it is not. > not yet... > > Or it has to be turned on manually? Why? > > Yes, with -ftree-vectorize, and -maltivec for PowerPC or -msse (or -msse2) > for x86. > > For more information see > http://gcc.gnu.org/projects/tree-ssa/vectorization.html#using. > the main reason why it hasn't been enabled by default so far was that we didn't have a cost model to evaluate whether it's worth while to vectorize or not (the vectorizer was too greedy). Now, in 4.3, we have a (very simplistic, initial) cost model, so there will probably be more effort in the near future to bring the vectorizer to some minimal stability level (e.g. pass bootstrap with vectorization enabled on most/important platforms, pass SPECcpu2006 with vectorization, etc) to be able to try out the adventure of turning it on by default... I hope we will get there soon. dorit > Ira > > > -- > > Zuxy > >
