> > So is this an object lesson for why optimizing for benchmarks is a bad > > idea? > > If you're inclined to believe this, you could find a confirming > instance here, but there are other lessons that could be drawn. If > you go back to the original thread, you'll see this from Toon Moene: > http://gcc.gnu.org/ml/gcc-patches/2004-09/msg00256.html > It didn't have to be a benchmark-only optimization.
It isn't a benchmark only optimization. Only the perfect nest conversion was targeted for the benchmarks, because it was necessary. The rest uses standard spatial optimality metrics to decide whether it makes sense to interchange loops or not, and *that* works great on fortran applications (except for a few other random bugs). You make it sound like the whole thing was targeted at SWIM, which is simply not the case at all. HTH, Dan
