For my test case, the entire inline instance is optimized away, so there is no info about it in the profile. I can do some fixup in the rebuild_cgraph_edge though.
Dehao On Mon, Oct 14, 2013 at 2:27 PM, Xinliang David Li <davi...@google.com> wrote: > Is it possible to update the callee node summary after profile > annotate (using information from inline instances which are not > inlined in early inline)? > > David > > On Mon, Oct 14, 2013 at 2:18 PM, Dehao Chen <de...@google.com> wrote: >> On Mon, Oct 14, 2013 at 12:49 PM, Jan Hubicka <hubi...@ucw.cz> wrote: >>>> Not for instrumented FDO (not as I know of). But for AutoFDO, this >>>> could be a potential risk because some callee is marked unlikely >>>> executed simply because they are inlined and eliminated in the O2 >>>> binary. But in ipa-inline it will not get inlined because the edge is >>>> not hot from cgraph_maybe_hot_edge_p (because callee is >>>> UNLIKELY_EXECUTED), while the edge->count is actually hot. >>> >>> Can't you prevent setting calle to UNLIKELY_EXECUTED in these cases instead? >>> It seems that having profile set incorrectly will lead to other problems >>> later, too. >>> We discussed similar problem with Teresa about the missing profiles for >>> comdat, >>> basically one should detect these cases as profile being lost and go with >>> guessed >>> profile. (I believe patch for that was posted, too, and so far it seems >>> best approach >>> to this issue) >> >> The current AutoFDO implementation will take all functions that do not >> have have profile as normally executed, thus use guessed profile for >> it. This is like using profile for truly hot functions, and using O2 >> for other functions. This works fine. However, it leads to larger code >> size (approximately 10%~20% larger than FDO). >> >> I'd like to introduce another mode for users who care about both >> performance and code size, and can be sure that profile is >> representative. In this mode, we will mark all functions without >> sample as "unlikely executed". However, because AutoFDO use debug info >> (of optimized code) to represent profile, it's possible that some hot >> functions (say foo) are inlined and fully eliminated into another hot >> function (say bar). So in the profile, bar is cold, and because the >> profile for foo::bar is eliminated, bar will not be inlined into foo >> before the profile annotation. However, after profile annotate, we can >> infer from the bb count that foo->bar is hot, thus it should be >> inlined in ipa-inline phase. However, because bar itself is marked >> UNLIKELY_EXECUTED, it will not be inlined. >> >> One possible workaround would be that during rebuild_cgraph_edges, if >> we find an edge's callee is unlikely executed, add the edge count to >> the callee's count and recalculate callee's frequency. >> >> Dehao >> >>> >>> Honza
