------- Additional Comments From rakdver at atrey dot karlin dot mff dot cuni dot cz 2005-05-22 21:23 ------- Subject: Re: missed optimization due with const function and pulling out of loops
> > > > Nevertheless, even if we are very strict with the definition, moving > > > > get_type2 out of the loop is not a good idea, since get_type2 might > > > > potentially be very expensive (and we have no way how to determine > > > > that this is not the case), thus we would lose in case get_type2 > > > > should be never executed. > > > > > > > > > > > > > > Don't we attempt to detect zero trip loops? > > > (If not, we should :P) > > > > I don't see how this is relevant to the PR. > > > > Uh, you claimed we won't move get_type2 out, even if it is const, > becuase it might not normally execute. > > If we can't prove we don't execute the loop, you should move it out. I still don't understand what you mean. > Otherwise, your logic would hold for get_type1 just the same, which we > *do* move out of the loop. > > IOW, there is no reason to move get_type1 out but not get_type2 The reason is that get_type1 is always executed when the loop is entered, while get_type2 is not. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21712
