[libFuzzer] more refactoring; don't compute sha1sum every time we mutate a unit from the corpus, use the stored one.
llvm-svn: 282115
diff --git a/llvm/lib/Fuzzer/FuzzerCorpus.h b/llvm/lib/Fuzzer/FuzzerCorpus.h
index 877a483..d42e7be 100644
--- a/llvm/lib/Fuzzer/FuzzerCorpus.h
+++ b/llvm/lib/Fuzzer/FuzzerCorpus.h
@@ -12,22 +12,26 @@
#ifndef LLVM_FUZZER_CORPUS
#define LLVM_FUZZER_CORPUS
+#include <random>
+
#include "FuzzerDefs.h"
+#include "FuzzerRandom.h"
namespace fuzzer {
struct InputInfo {
Unit U; // The actual input data.
+ uint8_t Sha1[kSHA1NumBytes]; // Checksum.
};
class InputCorpus {
public:
InputCorpus() {
- Corpus.reserve(1 << 14); // Avoid too many resizes.
+ Inputs.reserve(1 << 14); // Avoid too many resizes.
}
- size_t size() const { return Corpus.size(); }
- bool empty() const { return Corpus.empty(); }
- const Unit &operator[] (size_t Idx) const { return Corpus[Idx].U; }
+ size_t size() const { return Inputs.size(); }
+ bool empty() const { return Inputs.empty(); }
+ const Unit &operator[] (size_t Idx) const { return Inputs[Idx].U; }
void Append(const std::vector<Unit> &V) {
for (auto &U : V)
push_back(U);
@@ -37,18 +41,47 @@
if (!Hashes.insert(H).second) return;
InputInfo II;
II.U = U;
- Corpus.push_back(II);
+ memcpy(II.Sha1, H.data(), kSHA1NumBytes);
+ Inputs.push_back(II);
+ UpdateCorpusDistribution();
}
typedef const std::vector<InputInfo>::const_iterator ConstIter;
- ConstIter begin() const { return Corpus.begin(); }
- ConstIter end() const { return Corpus.end(); }
+ ConstIter begin() const { return Inputs.begin(); }
+ ConstIter end() const { return Inputs.end(); }
bool HasUnit(const Unit &U) { return Hashes.count(Hash(U)); }
+ const InputInfo &ChooseUnitToMutate(Random &Rand) {
+ return Inputs[ChooseUnitIdxToMutate(Rand)];
+ };
- private:
+ // 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.
+ size_t ChooseUnitIdxToMutate(Random &Rand) {
+ size_t Idx =
+ static_cast<size_t>(CorpusDistribution(Rand.Get_mt19937()));
+ assert(Idx < Inputs.size());
+ return Idx;
+ }
+
+private:
+
+ // Updates the probability distribution for the units in the corpus.
+ // Must be called whenever the corpus or unit weights are changed.
+ void UpdateCorpusDistribution() {
+ size_t N = Inputs.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());
+ }
+ std::piecewise_constant_distribution<double> CorpusDistribution;
+
std::unordered_set<std::string> Hashes;
- std::vector<InputInfo> Corpus;
+ std::vector<InputInfo> Inputs;
};
} // namespace fuzzer