[libFuzzer] experimental flag to tweak the corpus distribution. Seems to improve the situation dramatically on the png benchmark and make things worse on a number of micro-puzzles. Needs more A/B testing
llvm-svn: 315407
diff --git a/compiler-rt/lib/fuzzer/FuzzerLoop.cpp b/compiler-rt/lib/fuzzer/FuzzerLoop.cpp
index 4ccfe3f..c095fed 100644
--- a/compiler-rt/lib/fuzzer/FuzzerLoop.cpp
+++ b/compiler-rt/lib/fuzzer/FuzzerLoop.cpp
@@ -396,6 +396,7 @@
size_t FoundUniqFeaturesOfII = 0;
size_t NumUpdatesBefore = Corpus.NumFeatureUpdates();
TPC.CollectFeatures([&](size_t Feature) {
+ Corpus.UpdateFeatureFrequency(Feature);
if (Corpus.AddFeature(Feature, Size, Options.Shrink))
UniqFeatureSetTmp.push_back(Feature);
if (Options.ReduceInputs && II)
@@ -565,6 +566,8 @@
MD.StartMutationSequence();
auto &II = Corpus.ChooseUnitToMutate(MD.GetRand());
+ if (Options.UseFeatureFrequency)
+ Corpus.UpdateFeatureFrequencyScore(&II);
const auto &U = II.U;
memcpy(BaseSha1, II.Sha1, sizeof(BaseSha1));
assert(CurrentUnitData);
