Revert r258473 as it's breaking the build with libc++
Reviewers: kcc
Differential Revision: http://reviews.llvm.org/D16441
llvm-svn: 258479
diff --git a/llvm/lib/Fuzzer/FuzzerLoop.cpp b/llvm/lib/Fuzzer/FuzzerLoop.cpp
index a7e743e..7f3b0f5 100644
--- a/llvm/lib/Fuzzer/FuzzerLoop.cpp
+++ b/llvm/lib/Fuzzer/FuzzerLoop.cpp
@@ -163,7 +163,6 @@
if (UnitHashesAddedToCorpus.insert(Hash(X)).second) {
if (RunOne(X)) {
Corpus.push_back(X);
- UpdateCorpusDistribution();
PrintStats("RELOAD");
}
}
@@ -201,7 +200,6 @@
}
}
Corpus = NewCorpus;
- UpdateCorpusDistribution();
for (auto &X : Corpus)
UnitHashesAddedToCorpus.insert(Hash(X));
PrintStats("INITED");
@@ -349,7 +347,6 @@
void Fuzzer::ReportNewCoverage(const Unit &U) {
Corpus.push_back(U);
- UpdateCorpusDistribution();
UnitHashesAddedToCorpus.insert(Hash(U));
USF.GetMD().RecordSuccessfulMutationSequence();
PrintStatusForNewUnit(U);
@@ -412,11 +409,22 @@
// Returns an index of random unit from the corpus to mutate.
// Hypothesis: units added to the corpus last are more likely to be interesting.
-// This function gives more weight to the more recent units.
+// This function gives more wieght to the more recent units.
size_t Fuzzer::ChooseUnitIdxToMutate() {
- size_t Idx = static_cast<size_t>(CorpusDistribution(USF.GetRand()));
- assert(Idx < Corpus.size());
- return Idx;
+ size_t N = Corpus.size();
+ size_t Total = (N + 1) * N / 2;
+ size_t R = USF.GetRand()(Total);
+ size_t IdxBeg = 0, IdxEnd = N;
+ // Binary search.
+ while (IdxEnd - IdxBeg >= 2) {
+ size_t Idx = IdxBeg + (IdxEnd - IdxBeg) / 2;
+ if (R > (Idx + 1) * Idx / 2)
+ IdxBeg = Idx;
+ else
+ IdxEnd = Idx;
+ }
+ assert(IdxBeg < N);
+ return IdxBeg;
}
// Experimental search heuristic: drilling.
@@ -439,7 +447,6 @@
std::vector<Unit> SavedCorpus;
SavedCorpus.swap(Corpus);
Corpus.push_back(U);
- UpdateCorpusDistribution();
assert(Corpus.size() == 1);
RunOne(U);
PrintStats("DRILL ");
@@ -503,14 +510,4 @@
ExecuteCommand(Options.SyncCommand + " " + Options.OutputCorpus);
}
-void Fuzzer::UpdateCorpusDistribution() {
- size_t N = Corpus.size();
- std::vector<double> Intervals(N+1);
- std::vector<double> Weights(N);
- std::iota(Intervals.begin(), Intervals.end(), 0);
- std::iota(Weights.begin(), Weights.end(), 1);
- CorpusDistribution = std::piecewise_constant_distribution<double>(
- Intervals.begin(), Intervals.end(), Weights.begin());
-}
-
} // namespace fuzzer