[PATCH] D82123: [PGO] Add a functionality to always instrument the func entry BB

[David Li via Phabricator via llvm-commits]

davidxl added inline comments.


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Comment at: llvm/lib/Transforms/Instrumentation/CFGMST.h:110
+    // If we want to instrument the entry count, lower the weight to 0.
+    if (PGOInstrumentEntry)
+      EntryWeight = 0;
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Does this guarantee entry be instrumented?


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Comment at: llvm/lib/Transforms/Instrumentation/CFGMST.h:147
             Weight = BPI->getEdgeProbability(&*BB, TargetBB).scale(scaleFactor);
+          if (Weight == 0)
+            Weight++;
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Is this the way to make sure entry is always instrumented?


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Comment at: llvm/lib/Transforms/Instrumentation/CFGMST.h:292
     computeMinimumSpanningTree();
+    if (PGOInstrumentEntry && (AllEdges.size() > 1))
+      std::iter_swap(std::move(AllEdges.begin()),
----------------
is this needed? Can somthing be done in CompputeMST without relying on weight trick?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D82123/new/

https://reviews.llvm.org/D82123