> On Sat, May 1, 2010 at 2:36 AM, Jan Hubicka <hubi...@ucw.cz> wrote: > >> > >> Vortex needs -fno-strict-aliasing. It casts between two record types > >> with one record being a 'prefix' of another. > > > > So today runs are complette. Thanks to Richi who fixed ICE in symtab > > merging > > that affected perl and GCC. With vortex problem was that in addition to > > -fno-strict-aliasing it is writting to closed files that cause ICE > > depending on > > partiuclar glibc version. > > > > Comparing > > http://gcc.opensuse.org/SPEC/CINT/sb-frescobaldi.suse.de-fdo-64-FDO/recent.html > > vortex is 2036 with -O2 -flto, 2438 with -O2 -flto and FDO (so about 20% > > improvement) > > http://gcc.opensuse.org/SPEC/CINT/sb-frescobaldi.suse.de-head-64/list.html > > has -O2 runs without LTO that is 1859, so 31% for LTO+FDO, 10% LTO. > > > > Any idea if it is one of value transforms or just edge profile making the > > difference? There are some cases of write only globals we can constant > > propagate with -fwhole-program in SPEC, but I think it is parser. > > > > I got the following number for O2, FDO, and LIPO : 2351, 2761 (17%), 3448 > (24%). > > The FDO improvement over O2 come from both edge profile and vpt > (div,rem). With FDO, one of the important loops in Part_Delete may get
I see. I am particularly interested in the div/rem transform. With LTO such things are sometimes doable at compile time (propagating that the divisor is know constant value). We currently make no constant propagation across global variables except for simple detection if it is readonly and initialized. It would be possible to be a bit smarter here and look for vars that are only used to store a constant value into it and then replace all the division/rem by that constant counting on fact that the value 0 can not reach the division. Is this case detectable at compile time without feedback? Honza > tail duplicated which helps performance. > > LIPO improvement mainly come from cross module ininling of hot > functions Mem_GetWord, Mem_GetAddr, Chunk_ChkGetChunk. > > David > > > > Honza > >> > >> David > >> > >> > >> > >> > Honza > >> > > >
