Method FunctionWeights

fuzz/libfuzzer/FuzzerDataFlowTrace.cpp:89–104

Assign weights to each function. General principles: any uncovered function gets weight 0. a function with lots of uncovered blocks gets bigger weight. a function with a less frequently executed code gets bigger weight.

//   * a function with lots of uncovered blocks gets bigger weight.
//   * a function with a less frequently executed code gets bigger weight.
std::vector<double> BlockCoverage::FunctionWeights(size_t NumFunctions) const {
  std::vector<double> Res(NumFunctions);
  for (const auto &It : Functions) {
    auto FunctionID = It.first;
    auto Counters = It.second;
    assert(FunctionID < NumFunctions);
    auto &Weight = Res[FunctionID];
    // Give higher weight if the function has a DFT.
    Weight = FunctionsWithDFT.count(FunctionID) ? 1000. : 1;
    // Give higher weight to functions with less frequently seen basic blocks.
    Weight /= SmallestNonZeroCounter(Counters);
    // Give higher weight to functions with the most uncovered basic blocks.
    Weight *= NumberOfUncoveredBlocks(Counters) + 1;
  }
  return Res;
}

void DataFlowTrace::ReadCoverage(const std::string &DirPath) {
  std::vector<SizedFile> Files;