Method Apply

source/fuzz/fuzzer_pass_add_loop_preheaders.cpp:31–62

                 transformations, ignore_inapplicable_transformations) {}

void FuzzerPassAddLoopPreheaders::Apply() {
  for (auto& function : *GetIRContext()->module()) {
    // Keep track of all the loop headers we want to add a preheader to.
    std::vector<uint32_t> loop_header_ids_to_consider;
    for (auto& block : function) {
      // We only care about loop headers.
      if (!block.IsLoopHeader()) {
        continue;
      }

      // Randomly decide whether to consider this header.
      if (!GetFuzzerContext()->ChoosePercentage(
              GetFuzzerContext()->GetChanceOfAddingLoopPreheader())) {
        continue;
      }

      // We exclude loop headers with just one predecessor (the back-edge block)
      // because they are unreachable.
      if (GetIRContext()->cfg()->preds(block.id()).size() < 2) {
        continue;
      }

      loop_header_ids_to_consider.push_back(block.id());
    }

    for (uint32_t header_id : loop_header_ids_to_consider) {
      // If not already present, add a preheader which is not also a loop
      // header.
      GetOrCreateSimpleLoopPreheader(header_id);
    }
  }
}

}  // namespace fuzz
}  // namespace spvtools