The world’s biggest semiconductor corporations face a rising competitive threat: Their biggest clients making their own chips tailored to the jazzed-up areas of cloud-computing and artificial intelligence.Chip creating has long been ruled by giant manufacturers and design houses such as Intel Corp, Advanced Micro Devices Inc. and graphics-chip maker Nvidia Corp. Now Amazon.com.Inc., Microsoft Corp. and Google are stepping into the game in the hunt for better performance and lesser costs, changing the balance of power in the industry and pushing traditional chip makers to respond by building more specialized chips for major customers.Amazon this month revealed a new chip that promises to accelerate how algorithms that use artificial intelligence learn from data. The company has already created other processors for its cloud-computing arsenal, known as Amazon Web Services, including the brains of computers referred to as central processing units.