message: speed up DedupBlocks
  Summary: fastflash
diff: @@ -301,6 +301,8 @@ class DedupBlocksImpl {
  }
  void record_stats(const duplicates_t& duplicates) {
  + // avoid the expensive lock if we won't actually print the information
  + if (traceEnabled(RME, 2)) {
  std::lock_guard<std::mutex> guard{lock};
  for (const auto& entry : duplicates) {
  std::unordered_set<Block*> blocks = entry.second;
  @@ -309,6 +311,7 @@ class DedupBlocksImpl {
  m_dup_sizes[num_opcodes(block)] += blocks.size();
  }
  }
  + }
  void report_stats() {
  int eligible_blocks = m_num_eligible_blocks.load();
  