[PATCH] D73776: Entropic: Boosting LibFuzzer Performance

[Vitaly Buka via Phabricator via llvm-commits]

vitalybuka added inline comments.


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Comment at: compiler-rt/lib/fuzzer/FuzzerCorpus.h:41
   Vector<uint8_t> DataFlowTraceForFocusFunction;
+  // Power schedule.
+  bool NeedsUpdate;
----------------
it would be nice to manipulate this fields only with reasonable named methods


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Comment at: compiler-rt/lib/fuzzer/FuzzerCorpus.h:43
+  bool NeedsUpdate;
+  double Energy;
+  size_t Sum_Y;
----------------
could you please initialize them?


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Comment at: compiler-rt/lib/fuzzer/FuzzerCorpus.h:387
+    size_t Y = 0;
+    size_t Sum_Y = 0;
+    long double Energy = 0.0L;
----------------
It would be nice to rename variables in a such way that reader without background can understand what is going on.


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Comment at: compiler-rt/lib/fuzzer/FuzzerCorpus.h:395
+    for (auto F : II->FeatureFreqs) {
+      Y = F.second + 1;
+      Energy -= Y * logl(Y);
----------------
please don't reuse variables like Y here
just declare as close as possible to first use, or even better with assignment


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Comment at: compiler-rt/lib/fuzzer/FuzzerCorpus.h:530
+  uint16_t FreqOfMostAbundantRareFeature = 0;
+  uint16_t GlobalFeatureFreqs[kFeatureSetSize];
+  Vector<uint32_t> RareFeatures;
----------------
uint16_t GlobalFeatureFreqs[kFeatureSetSize] = {}; instead of memsets
it would be nice do to the same for other arrays here, but in a separate patch


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Comment at: compiler-rt/lib/fuzzer/FuzzerFlags.def:156
      "will choose the focus functions automatically.")
+FUZZER_FLAG_INT(entropic, 0, "Experimental. Enables entropic power schedule.")
+FUZZER_FLAG_INT(considered_rare, 0xFF, "Experimental. If entropic is enabled, "
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entropic -> focus_rare_features


Not sure how, it would be nice to rename sparse_energy_updates as something meaningful to libfuzzer user, to make it explain behavior change, not implementation details like now.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D73776/new/

https://reviews.llvm.org/D73776