On 03/06/2014 03:14 PM, Paulo J. Matos wrote: > On 06/03/14 15:15, Vladimir Makarov wrote: >> On 03/06/2014 08:55 AM, Paulo Matos wrote: >>> Hi, >>> >>> Upon noticing ira-hoist-pressure in `gcc --help=optimizers` and not >>> ira-loop-pressure, >>> I am wondering why the latter is not marked as an Optimization in >>> common.opt: >>> >>> fira-loop-pressure >>> Common Report Var(flag_ira_loop_pressure) >>> Use IRA based register pressure calculation >>> in RTL loop optimizations. >>> >>> Should we mark it as such? >>> >>> >> It is not an optimization strictly speaking. It is a better register >> pressure calculation used for invariant loop motion decisions. >> >> On the other hand, using this option can improve generated code >> performance (e.g. as I remember it improved SPECFP2000 by 1% for >> ppc64). So I guess, it should mark as such in order to see this >> possibility to improve the code by a programmer. >> >> > > I have just run a few long benchmarks and even though I had high > expectations for improving performance the flag in our port causes a > ~3% degradation in performance. Haven't had time to investigate why. >
Strange. What port is this? Can I see the benchmarks. I know Pat Haugen from IBM found a bug which can generated worse code in some cases and has a fix. I hope Pat submits it on stage 1. > Still, would you accept a patch to mark this flag as an optimization? > I think we should.
