From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Booth To: Mike Stump Cc: gcc@gcc.gnu.org Subject: Re: Faster compilation speed Date: Fri, 09 Aug 2002 14:29:00 -0000 Message-id: <20020809212702.GD21900@daikokuya.co.uk> References: X-SW-Source: 2002-08/msg00505.html Mike Stump wrote:- > I'd like to introduce lots of various changes to improve compiler > speed. Just my opinion, Mike, but I think a lot of current slowness is due to redo-ing too many things, and not taking advantage of ordering or whatever technique so that conclusions deduced from internal representations are made in a logical, efficent way. (e.g. I think we try to constant fold things that we've already tried to constant fold and failed, repeatedly, and we don't do the constant folding we do do in an optimal way. I could be wrong, though; I've not looked in detail). I cannot explain this clearly, or with any specific example, but IMO we work far too hard to do what we do. I'd like to see this cleaned up instead. For example, see some of Mark's recent patches. I think we could continue doing that for ages. I also believe that using Bison (and our ill-considered extensions like attributes pretty much anywhere) don't help efficiency. We could probably do better in the C front end with a tree representation that is closer to C than the current multi-language form of trees. What worries me about PCH and similar schemes is it's too easy to fix the symptoms, rather than the real reasons for the slowness. As a result, such things might never be fixed. Neil.