On Tue, Jul 3, 2012 at 12:37 PM, Richard Smith <[email protected]> wrote: > On Tue, Jul 3, 2012 at 1:14 AM, Joerg Sonnenberger <[email protected]> > wrote: >> >> On Mon, Jul 02, 2012 at 11:23:05PM -0000, Richard Smith wrote: >> > Log: >> > -Wuninitialized: assume that an __attribute__((returns_twice)) function >> > might >> > initialize any variable. This is extremely conservative, but is >> > sufficient for >> > now. >> >> Can this be reduced to following both code paths if the function call is >> part of a conditional? > > > I'm not sure what you're suggesting; we do follow both code paths after a > conditional. If you mean that we should track whether the function returned > a nonzero value, and not apply this logic in that case, then I think that's > out of scope for this check, and belongs in the static analyzer (if > anywhere). > >> >> When I analysed the newly triggered warnings for >> -Wuninitialized in NetBSD, setjmp usage was something like 50% >> questionable w.r.t. conditional initialisation, so getting this more >> strict or optional is definitely a good idea. > > > If we want to make this smarter, I think the way to approach it is to find > variable initializations which are reachable from the returns_twice call > (optionally only looking at ones where there is a function call afterwards), > and to assume that all relevant variables are initialized by the setjmp > call. But we would need to find an inexpensive way of computing this > information. Perhaps a reasonable tradeoff would be to compute a set of > variables which are initialized anywhere within the function, and to assume > that setjmp initializes them all. > > It might also be valuable to separate the setjmp case (which needs this > special handling) from the fork case (which does not), but we don't > currently have attributes to track that.
Err, IIRC we don't mark fork() as returns_twice. -Eli _______________________________________________ cfe-commits mailing list [email protected] http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
