copy(preds2, preds)
		state.logf("Merging %v into %v (changed=%d, checked=%d)\n", preds2, b, locs.lastChangedTime, locs.lastCheckedTime)
	}

	state.changedVars.clear()

	markChangedVars := func(slots, merged abt.T) {
		if !forLocationLists {
			return
		}
		// Fill changedVars with those that differ between the previous
		// block (in the emit order, not necessarily a flow predecessor)