Vladimir Makarov wrote: > I remember nocona tunning gave 30% improvement SPECFp2000 for Intel > nocona in 64 bit mode in comparison with the default x86_64 gcc tuning > (for k8). So such big improvement is definetly mostly from new > -mtune=generic.
Well, then, lets get numbers for other targets! I'd love to see the same data for PowerPC, MIPS, etc. This discussion will be much more productive in the presence of data. There are no absolutes: it's not "we can't ship with bugs", "we can't ship with performance regressions", etc. We've got to balance quality on various axes, and to do that we need to know the numbers. Also, it's FSF compilers I'm concerned about, not distribution compilers. After all, we're talking about FSF releases. Many people use FSF releases directly, or indirectly via distributions (GNU/Linux and otherwise) other than Red Hat and Novell. It's true that Red Hat and Novell put various things into their 4.1 compilers (like -mtune=generic) that are a win; that's part of their value-add. However, they can similarly modify 4.2 compilers (if they ship them) by, for example, trading potential aliasing bugs for performance, if that seems like a win. It doesn't make sense to compare unmodified FSF 4.2 compilers with distribution-optimized 4.1 compilers. Thanks, -- Mark Mitchell CodeSourcery [EMAIL PROTECTED] (650) 331-3385 x713
