Academically, companies buy back their shares to increase shareholder value. But there could be other reasons, for instance, to prevent or make it harder for another company to take it over. I’m not at all suggesting that any of the companies mentioned in the article are acquisition targets, however. But it is something to think about. Also, semi companies are definitely being conservative with their R&D plans, and while the idea of using the cash to increase their engineering workforces and gear up for when the market returns to double-digit growth is one that would make sense, companies are still doing the opposite. And there are no indications (in the short-term anyway) that the trend will reverse itself in a big way.
The maxim "buy low; sell high" should also apply when buying back your own stock, but, tragically, it usually doesn't. Study after study have shown that stock buybacks usually occur at a stock price peak, rather than at a nadir. If the stocks are so undervalued now, why weren't they even more undervalued at the stock market bottom, and why didn't you buy then instead of now?
I don't know the math behind repurchase, but some companies did that before while there was no sign of advantage at all, at least from their stock price.
I think if the company is strong in cash flow, the better way to spend the money is to further invest on human capital (recruit more talents) and acquire good value companies.