hi mark, On Mon, 2005-12-05 at 21:33 -0800, Mark Mitchell wrote:
> I'm not saying that having two different formats is necessarily a bad > thing (we've already got Tree and RTL, so we're really talking about two > levels or three), or that switching to LLVM is a bad idea, but I don't > think there's any inherent reason that we must necessarily have multiple > representations. In what I admit is a relatively limited experience (compared to that of you or other gcc contributors) of working with a few large old sucky codebases, I think I have learned one thing: genericity is most often bad. Specifically, I think that trying to re-use the same data structure/algorithms/code for widely different scenarios is what most often leads to large overall complexity and fragility. It seems to me that the advantages of using the LTO representation for frontend-dumping and optimization (code reuse, etc.) are not worth the cost (a single piece of code used for two very different use-cases will necessarily be more complex and thus prone to design bugs). Hubris will lead developers to ignore the latter because they believe they can avoid the complexity trap of code reuse. It might work in the short term because you and others might be able to achieve this feat but I fail to see how you will be able to avoid the inevitable decay of code inherent to this solution in the long run. A path where different solutions for different problems are evolved independently and then merged where it makes sense seems better to me than a path where a single solution to two different problems is attempted from the start. Which is thus why I think that "there are inherent reasons that you must necessarily have multiple representations". regards, Mathieu PS: I know I am oversimplifying the problem and your position and I apologize for this. --
