Re: What to do about compile time slowdowns for 4.1?

[Sebastian Pop <sebastian dot pop at cri dot ensmp dot fr>]

Daniel Berlin wrote:
> 
> I agree completely.
> We need to be a lot smarter about invalidating certain types of
> expensive to compute information.  

The way that we compute niter, for the moment, could be considered as
not expensive.  But the fact that we think that this is inexpensive
makes us commit the error to invalidate the information too many
times.  There surely are reasons to invalidate this information, for
example after aggressive scalar loop optimizations, ie. ivopts, but
there are other passes like VRP or vectorizer that build the
information and just discard it without having scrambled too much the
code.