https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102943
--- Comment #33 from hubicka at kam dot mff.cuni.cz --- With the inliner tweaks (which I hope to get bit more aggressive this week) we "solved" the wrf compile time with LTO by simply not building the gigantic functions. However we still have significant regressions without LTO. Accroding to https://lnt.opensuse.org/db_default/v4/SPEC/spec_report/branch With spec2006 on kabylake with _O2 we have: Test Name gcc-6 gcc-7 gcc-8 gcc-9 gcc-10 gcc-11 gcc-trunk SPECFP 256.464 3.59% 15.50% 19.29% 29.53% 33.44% 43.50% SPECint 119.368 3.17% 13.60% 17.23% 14.17% 26.58% 33.58% and spec2007 SPECFP 638.337 5.39% 21.20% 25.40% 50.18% 45.00% 58.72% SPECint 217.977 4.03% 11.47% 16.17% 13.29% 22.52% 27.28% Growing SPECFP -O2 build time by over 10% in one release is quite a lot though it happened previously with gcc7->gcc8 and gcc9->gcc10 (if I remember correctly gcc10 was caused by Fortran revisiting libgfortran API and increasing binaries significantly). The bigger increase in SPECfp compared to SPECint seems to be attributed to wrf which regresses 122% compared to gcc6. The build time graph is here https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=116.548.8&plot.1=161.548.8&plot.2=68.548.8&plot.3=206.548.8&plot.4=373.548.8&plot.5=430.548.8&plot.6=30.548.8&; So I think this is still about the most important compile time issue we have. I plan to look at the profile updating issues in threader and hopefully get bit more faimilar with the code to possibly help here.
