[PATCH] D30053: Add function importing info from samplepgo profile to the module summary.

[Mehdi AMINI via Phabricator via llvm-commits]

mehdi_amini added inline comments.


================
Comment at: lib/Analysis/ModuleSummaryAnalysis.cpp:188
+    CallGraphEdges[I].updateHotness(CalleeInfo::HotnessType::Hot);
+
   bool NonRenamableLocal = isNonRenamableLocal(F);
----------------
danielcdh wrote:
> mehdi_amini wrote:
> > I'm still unsure why we need this side channel to communicate the hotness, while we have above already some infrastructure? Why isn't samplePGO integrate in the general PGO infrastructure?
> The root cause is the profile annotation mechanism is different.
> 
> SamplePGO needs to make sure that before profile annotation, the IR resembles the hot portion of the profiling binary. As a result, we need to explicitly inline functions before profile annotation. But in order to inline, we need to first have it imported.
> 
> I can go into more details with an example if you want. Please let me know.
I'm still not fond of this "side channel", and I rather have a solution that annotates hot calls in the IR instead, that would be agnostic to the source of information we derive this "hotness" from.


https://reviews.llvm.org/D30053