computeImmediateDominators() — react Function Reference

Source Code

compiler/packages/babel-plugin-react-compiler/src/HIR/Dominator.ts lines 151–194

function computeImmediateDominators<T>(graph: Graph<T>): Map<T, T> {
  const nodes: Map<T, T> = new Map();
  nodes.set(graph.entry, graph.entry);
  let changed = true;
  while (changed) {
    changed = false;
    for (const [id, node] of graph.nodes) {
      // Skip start node
      if (node.id === graph.entry) {
        continue;
      }

      // first processed predecessor
      let newIdom: T | null = null;
      for (const pred of node.preds) {
        if (nodes.has(pred)) {
          newIdom = pred;
          break;
        }
      }
      CompilerError.invariant(newIdom !== null, {
        reason: `At least one predecessor must have been visited for block ${id}`,
        loc: GeneratedSource,
      });

      for (const pred of node.preds) {
        // For all other predecessors
        if (pred === newIdom) {
          continue;
        }
        const predDom = nodes.get(pred);
        if (predDom !== undefined) {
          newIdom = intersect(pred, newIdom, graph, nodes);
        }
      }

      if (nodes.get(id) !== newIdom) {
        nodes.set(id, newIdom);
        changed = true;
      }
    }
  }
  return nodes;
}