Among chip companies, Advanced Micro Devices is hardly a safe bet. But betting against it is no longer a sure thing either.

The oft-beleaguered chipmaker’s share price has more than doubled since the start of the year, making it the top gainer in the PHLX Semiconductor Index for that time. That can be credited to improving financial performance and hopes for a new family of chips designed for servers, PCs and videogame consoles. Most of the chips aren’t expected to launch until next year.

PCs...