search for: generateallreuseformula

I just filed bug 7872 about non-scalability of the LSR analysis algorithms. It may be related to bug 6727. The fundamental problem appears to be re-running SCEV analyses such as properlyDominates and SCEVComplexityCompare over and over again on large SCEV expressions. Memoizing results for SCEVComplexityCompare appears to help significantly but that is much harder to do with things like

I also noticed LSR spending a lot of time in GenerateAllReuseFormulae, just to have some cases pruned in NarrowSearchSpaceUsingHeuristics. I'm not familiar enough with the code to comment on how this affects the quality of LSR results, but a hack is to "EstimateSearchSpaceComplexity" inside the loops of GenerateAllReuseFormulae and cut out early. - Ja...