On Fri, Jan 12, 2018 at 10:45:31PM +0100, Arnd Bergmann wrote: > > I guess you could enable the _x routines whenever you use ubsan? Ubsan > > will cause much bigger code growth than the handful of insns in those > > routines? > > Right, that could work, too. My patch that Herbert merged intentionally > used -Os also for non-UBSAN builds because it turned out to > be much faster (see gcc PR83651), "Much"? -Os is *slower* with 8.0, 5% faster with 7.2, 4% faster with 7.1, slower with 7.0 and 6.3. Your numbers, #c1. Anf this is the generic code of course, which is slow anyway (not to mention insecure). > but we could revert that back > to the default and only use the -Os for UBSAN, essentially > addressing only PR83356 but not PR83651. Segher
