http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50346
--- Comment #5 from rguenther at suse dot de <rguenther at suse dot de> 2011-10-12 12:44:15 UTC --- On Wed, 12 Oct 2011, scovich at gmail dot com wrote: > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50346 > > --- Comment #4 from Ryan Johnson <scovich at gmail dot com> 2011-10-12 > 12:40:25 UTC --- > (In reply to comment #3) > > Well, it's a tree optimization issue. It's simple - the local aggregate f > > escapes the function via the member function call to baz: > > > > <bb 5>: > > foo::baz (&f); > > > > and as our points-to analysis is not flow-sensitive for memory/calls this > > causes f to be clobbered by the call to bar > > Is flow-sensitive analysis within single functions prohibitively expensive? > All > the papers I can find talk about whole-program analysis, where it's very > expensive in both time and space; the best I could find (CGO'11 best paper) > gets it down to 20-30ms and 2-3MB per kLoC for up to ~300kLoC. It would need a complete rewrite, it isn't integratable into the current solver (which happens to be shared between IPA and non-IPA modes). > > as neither the bodies of baz nor bar are visible there is nothing we can do > > Would knowing the body of bar() help if the latter cannot be inlined? Not at present, but it's possible to improve mod-ref analysis on an IPA level then. Richard.
