Steve Ellcey wrote: >> It came up in a few side conversations. As I understand it, RMS has >> decreed that the -On optimizations shall be architecture independent. >> That said, there are "generic" optimizations which really only apply >> to a single architecture, so there is some precedent for bending this >> rule. > > This seems unfortunate.
As others have said downthread, I don't think the idea that -O2 should enable the same set of optimizations on all processors is necessary or desirable. (In fact, there's nothing inherent in even using the same algorithms on all processors; I can well imagine that the best register allocation algorithms for x86 and Itanium might be entirely different. I'm in no way trying to encourage an entire set of per-achitecture optimization passes; clearly the more we can keep common the better! But, our goal is to produce a compiler that generates the best possible code on multiple architectures, not to produce a compiler that uses the same algorithms and optimization options on all architectures.) I have never heard RMS opine on this issue. However, I don't think that this is something that the SC or FSF need to decide. The SC has made very clear that it doesn't want to interfere with day-to-day technical development of the compiler. If the consensus of the maintainers is that it's OK to turn on some extra optimizations at -O2 on Itanium, then I think we can just make the change. Of course, if people would prefer that I ask the SC, I'm happy to do so. -- Mark Mitchell CodeSourcery [EMAIL PROTECTED] (650) 331-3385 x713
