}
		case BlockRetJmp:
			if len(b.Succs) != 0 {
				f.Fatalf("retjmp block %s len(Succs)==%d, want 0", b, len(b.Succs))
			}
			if b.NumControls() != 1 {
				f.Fatalf("retjmp block %s has nil control", b)
			}
			if !b.Controls[0].Type.IsMemory() {
				f.Fatalf("retjmp block %s has non-memory control value %s", b, b.Controls[0].LongString())
			}
		case BlockPlain:
			if len(b.Succs) != 1 {

				return false
			}
			for i := range fb.Values {
				if !checkVal(fb.Values[i], gb.Values[i]) {
					return false
				}
			}
			if len(fb.Succs) != len(gb.Succs) {
				return false
			}
			for i := range fb.Succs {
				if !checkBlk(fb.Succs[i].b, gb.Succs[i].b) {
					return false
				}
			}
			if len(fb.Preds) != len(gb.Preds) {
				return false
			}
			for i := range fb.Preds {

		Stmt:  stmt,
	}
	block.Succs = block.succs2[:0]
	g.Blocks = append(g.Blocks, block)
	return block
}

func (b *builder) add(n ast.Node) {
	b.current.Nodes = append(b.current.Nodes, n)
}

// jump adds an edge from the current block to the target block,
// and sets b.current to nil.
func (b *builder) jump(target *Block) {
	b.current.Succs = append(b.current.Succs, target)
	b.current = nil
}

func (b *Block) removeSucc(i int) {
	n := len(b.Succs) - 1
	if i != n {
		e := b.Succs[n]
		b.Succs[i] = e
		// Update the other end of the edge we moved.
		e.b.Preds[e.i].i = i
	}
	b.Succs[n] = Edge{}
	b.Succs = b.Succs[:n]
	b.Func.invalidateCFG()
}

func (b *Block) swapSuccessors() {
	if len(b.Succs) != 2 {
		b.Fatalf("swapSuccessors with len(Succs)=%d", len(b.Succs))
	}
	e0 := b.Succs[0]

	// Check if newsuccs is the same set as succs.
	succs := s[data.controls:]
	newsuccs := t[outdata.controls:]
	m := map[string]bool{}
	for _, succ := range succs {
		if m[succ] {
			log.Fatalf("can't have a repeat successor name %s in %s", succ, rule)
		}
		m[succ] = true
	}
	for _, succ := range newsuccs {
		if !m[succ] {
			log.Fatalf("unknown successor %s in %s", succ, rule)
		}
		delete(m, succ)
	}

        // Adding the class hashCode to avoid a clash with Succ instances.
        return Pred.class.hashCode() + node.hashCode();
      }
    }

    static final class Succ<N> extends NodeConnection<N> {
      Succ(N node) {
        super(node);
      }

      @Override
      public boolean equals(@CheckForNull Object that) {
        if (that instanceof Succ) {
          return this.node.equals(((Succ<?>) that).node);

				// A variable is live on output from this block
				// if it is live on input to some successor.
				//
				// out[b] = \bigcup_{s \in succ[b]} in[s]
				newliveout.Copy(lv.blockEffects(b.Succs[0].Block()).livein)
				for _, succ := range b.Succs[1:] {
					newliveout.Or(newliveout, lv.blockEffects(succ.Block()).livein)
				}
			}

			if !be.liveout.Eq(newliveout) {
				change = true
				be.liveout.Copy(newliveout)
			}

		break
	case BlockDefer:
		// we know nothing about control flow, add all branch destinations
		t.edges = append(t.edges, block.Succs...)
	case BlockFirst:
		fallthrough // always takes the first branch
	case BlockPlain:
		t.edges = append(t.edges, block.Succs[0])
	case BlockIf, BlockJumpTable:
		cond := block.ControlValues()[0]
		condLattice := t.getLatticeCell(cond)
		if condLattice.tag == bottom {

		// is the header block.  This implies that b.Succs[0] is
		// reached iff ind < limit.
		if len(b.Succs[0].b.Preds) != 1 {
			// b.Succs[1] must exit the loop.
			continue
		}

		// Second condition: b.Succs[0] dominates nxt so that
		// nxt is computed when inc < limit.
		if !sdom.IsAncestorEq(b.Succs[0].b, nxt.Block) {

    }
  }

  for (auto succ : GetSuccessors(op)) {
    if (is_cluster_op && !IsTpuRegularOp(succ) && has_cluster_metadata) {
      if (!CheckReplicatedIOOp(succ, metadata_map[cluster], op)) return false;
    }
    if (is_cluster_op && IsTpuRegularOp(succ)) {
      if (!CheckClusterSuccessors(succ, cluster, op, metadata_map))
        return false;
    }
    if (!is_cluster_op) {