https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125305
--- Comment #9 from chenglulu <chenglulu at loongson dot cn> --- (In reply to Xi Ruoyao from comment #5) > I can still observe performance gain from scheduling on LA664 for e.g. > https://git.kernel.org/torvalds/c/9805f39d423a. > > AArch64 is even using 10 for > TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD (when tuning for a core > with such an issue rate) but they disable early scheduling at -O2 and only > enable it at -O3 by default (they once disabled it at all but then lbm > regressed for 6% on neoverse, again demonstrating the usefulness of > scheduling even on OoO core). > > x86 disables early scheduling by default for any optimization level. > > IMO we should try disabling early scheduling for OoO cores like AArch64 or > x86 instead of modifying the lookahead, so the people requiring "top > performance" can still bring it back with -fschedule-insns. And I think we > need some benchmark results to make the decision. I see what you mean now. However, I found that passing -fno-schedule-insns during compilation still does not reduce the compilation time. According to the -ftime-report, the prolonged compilation time is due to the fact that the vast majority of the time is being spent in the sched2 pass.
