> On 3/8/19 1:44 PM, Jan Hubicka wrote: > >> Hi. > >> > >> Thanks to Intel guys, we've done some re-measurement in PR86952 > >> about usage of jump tables when retpolines are used. > >> Numbers prove that disabling of JT should be the best for now. > >> > >> Patch can bootstrap on x86_64-linux-gnu and survives regression tests. > >> > >> Ready to be installed? > > > > OK, thanks! > > I wonder if there is some threshold for extremely large jumptables where > > branchy sequence will loose, but I think it is better to disable them > > than what we have right now. > > I tested switch statements up to 4096 and it was still slower ;)
Well, we have switch statements with this many cases in insn-attrtab/latencytab tables. I suppose what kind of code you compile with retpolines, but I would expect even bigger switch statements to appear in real code (large DFA automatons and such) Honza > > Martin > > > > > Honza > > >
