std::vector Summarize()

in src/tir/transforms/thread_storage_sync.cc [52:192]
127 lines of code
42 McCabe index (conditional complexity)

  std::vector<AccessEntry> Summarize(std::vector<StmtEntry> seq, const ForNode* loop) final {
    // Redirect all "shared.dyn" buffer access to the same buffer var
    // so that the accesses can be planned together.
    Var shared_dyn_buf;
    for (StmtEntry& entry : seq) {
      for (AccessEntry& access : entry.access) {
        if (access.scope.rank == StorageRank::kShared && access.scope.tag == ".dyn" &&
            access.buffer.defined()) {
          if (!shared_dyn_buf.defined()) {
            shared_dyn_buf = access.buffer;
          } else {
            access.buffer = shared_dyn_buf;
          }
        }
      }
    }

    // Unsynced reads and writes
    std::vector<AccessEntry> reads;
    std::vector<AccessEntry> writes;
    // if it is a loop, rotate two times to consider effect of loop.
    // simulation based approach to find dependencies
    for (size_t i = 0; i < seq.size(); ++i) {
      const StmtEntry& s = seq[i];
      // check if sync before statement is needed.
      bool sync_before_stmt = (syncs_inserted_.count(s.stmt) != 0);
      // Apply the syncs added already.
      if (sync_before_stmt) {
        reads.clear();
        writes.clear();
      }
      for (const AccessEntry& acc : s.access) {
        if (acc.type == kRead) {
          if (FindConflict(writes, acc, false)) {
            sync_before_stmt = true;
            break;
          }
        } else if (acc.type == kWrite) {
          if (FindConflict(reads, acc, false)) {
            sync_before_stmt = true;
            break;
          }
        } else if (acc.type == kSync) {
          reads.clear();
          writes.clear();
        }
      }
      // If sync is inserted. remove the irrelevant things.
      if (sync_before_stmt) {
        reads.clear();
        writes.clear();
      }
      // Add the read/write of current statement
      for (const AccessEntry& acc : s.access) {
        if (acc.type == kRead) {
          reads.push_back(acc);
        } else if (acc.type == kWrite) {
          writes.push_back(acc);
        } else if (acc.type == kSync) {
          reads.clear();
          writes.clear();
        }
      }
      if (sync_before_stmt) {
        ICHECK_EQ(condition_counter(), 0) << "Cannot insert syncs inside condition";
        syncs_inserted_.insert(s.stmt);
      }
    }
    if (loop != nullptr) {
      for (size_t i = 0; i < seq.size(); ++i) {
        const StmtEntry& s = seq[i];
        if (syncs_inserted_.count(s.stmt) != 0) break;
        if (reads.empty() && writes.empty()) break;
        bool sync_before_stmt = false;
        for (const AccessEntry& acc : s.access) {
          if (acc.type == kRead) {
            if (FindConflict(writes, acc, true)) {
              sync_before_stmt = true;
              break;
            }
          } else if (acc.type == kWrite) {
            if (FindConflict(reads, acc, true)) {
              sync_before_stmt = true;
              break;
            }
          } else if (acc.type == kSync) {
            reads.clear();
            writes.clear();
          }
        }
        if (sync_before_stmt) {
          ICHECK_EQ(condition_counter(), 0) << "Cannot insert syncs inside condition";
          syncs_inserted_.insert(s.stmt);
          break;
        }
      }
    }
    // return the exposed entries, remove unecessary ones.
    int sync_count = 0;
    // head are before first sync, tail are after last sync
    std::vector<AccessEntry> head, tail;
    AccessEntry esync;
    esync.threads = this->env_threads();
    esync.type = kSync;
    esync.scope = sync_scope_;

    for (const StmtEntry& s : seq) {
      if (syncs_inserted_.count(s.stmt)) {
        if (sync_count != 0) {
          tail.clear();
        } else {
          head.push_back(esync);
        }
        ++sync_count;
      }
      for (const AccessEntry& acc : s.access) {
        if (acc.type == kSync) {
          if (sync_count != 0) {
            tail.clear();
          } else {
            head.push_back(esync);
          }
          ++sync_count;
        } else {
          if (sync_count != 0) {
            tail.push_back(acc);
          } else {
            head.push_back(acc);
          }
        }
      }
    }
    head.insert(head.end(), tail.begin(), tail.end());
    if (loop != nullptr) {
      // clear double buffer flag after a loop is finished.
      for (AccessEntry& e : head) {
        e.double_buffer_write = false;
      }
    }
    return head;
  }