------- Comment #155 from rguenther at suse dot de 2007-05-24 10:11 ------- Subject: Re: [4.0/4.1/4.2/4.3 Regression] placement new does not change the dynamic type as it should
On Thu, 24 May 2007, rguenther at suse dot de wrote: > So I did some benchmarking with my two proposed patches (which I believe > will fix all current issues - that I know of) on IA64 which should be > sensitive to the more restrictive scheduling. [You can look yourself > at the results starting from http://www.suse.de/~gcctest/, the run > without the patches is from late May23th the run with the patch from > early May24th] > > I'll try to summarize only here. > > - SPECfpu2000 shows both winners and loosers, the net change is > slightly positive for -O3 and slightly negative for -O3 -funroll-loops > (slightly means +3 points vs. -4 points) > > - SPECint2000 shows more variance in single tests, crafty winning for > peak, parser loosing for base, eon winning overall, likewise bzip. > Overall we get a drop in SPECint of about 3 points (0.3%) > > - Polyhedron is mostly the same, aermod regressing 1.5%, induct > improving 1%. > > - The set of C++ benchmarks (including TraMP-3d, DLV, Boost wave and > others) show no changes. > > Of course this doesn't prove anything - it only hints that it might be > not as bad as you thought. And no, I don't have a Power6 machine to > test on yet. Btw, in case you are curious - on http://www.suse.de/~gcctest/c++bench/tramp3d/split-run.html you can see the effects of the asm() memory barrier as proposed by one of Ians patches and the effect of forcing -fno-strict-aliasing on (the two spikes in runtime, the later one is -fno-strict-aliasing, the earlier one is the asm()). Both approaches disable moving loop invariant loads which is one thing you retain with my proposed slightly changed TBAA rules. Richard. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29286
