postDominatorFrontier() — react Function Reference

Source Code

compiler/packages/babel-plugin-react-compiler/src/Inference/ControlDominators.ts lines 66–88

function postDominatorFrontier(
  fn: HIRFunction,
  postDominators: PostDominator<BlockId>,
  targetId: BlockId,
): Set<BlockId> {
  const visited = new Set<BlockId>();
  const frontier = new Set<BlockId>();
  const targetPostDominators = postDominatorsOf(fn, postDominators, targetId);
  for (const blockId of [...targetPostDominators, targetId]) {
    if (visited.has(blockId)) {
      continue;
    }
    visited.add(blockId);
    const block = fn.body.blocks.get(blockId)!;
    for (const pred of block.preds) {
      if (!targetPostDominators.has(pred)) {
        // The predecessor does not always reach this block, we found an item on the frontier!
        frontier.add(pred);
      }
    }
  }
  return frontier;
}