// created by decomposition.
constexpr int kMaxIterations = 20;

// Populates `reachable_functions` with all functions that can be reached from
// device cluster ops.
void PopulateClusterReachableFunctions(
    ModuleOp module, SmallPtrSetImpl<Operation*>& reachable_functions) {
  SymbolTableCollection table;
  SymbolUserMap symbol_map(table, module);

  // Create map from caller to set of all callee(s).