on 22/12/2012 13:21 Konstantin Belousov said the following: > This is due to the vtoslab() returning NULL. Since slabref is dereferenced > later, clang tries to be helpful as usual and converts the !(p->flags & > PG_SLAB) case from vtoslab() into the jump to un2 instruction if vtoslab() > result is NULL. > > So instead of KASSERT triggering the next line, you see this improvement.
Interesting. Thank you for the explanation. But looking at the code I think that slabref->us_keg access _before_ KASSERT is the culprit? I.e. even with GCC we could get a page fault before the KASSERT is reached (modulo reordering)? -- Andriy Gapon _______________________________________________ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
