IIRC AMD's first x86 chip was reverse engineered from Intel's design.
Aye. Jerry Sanders authorized the Am386 program - Project Longhorn, in 1989. Fully reverse-engineered using only publicly available information. Didn't stop Intel winning IP infringement damages of $58m in 1995 (offset by AMD winning $10m in damages in 1993, $18m plus a 386 license and the right to outsource 20% of x86 production to third-party foundries in 1995)
Based on PRC's history, we have no doubt that they will steal and strongarm some company (TSMC,Samsung or one of their homegrown foundries?) to produce copies.
Or maybe just gobble up a foundry company like SMIC that have all but been squeezed out of the business.
Intel refused to license x86 so reverse engineering was the only option. Then came IBM which, in order to use Intel CPUs, they demanded Intel license it out (especially to AMD) because they wouldn't work with a monopoly.
It actually happened in the opposite order. IBM demanded a second source for the 8088/8086 because Intel were a relatively new (and small) player in the market - and the bulk of their foundry capacity was given over to high profit DRAM and EPROM. By the time the 386 arrived, IBM was largely a spent force in the PC market (Microsoft and Intel had gained dominance thanks to the 80286 PC clone market). Intel basically kept AMD hanging with regards the 386. Intel had no use for a licensed competitors any more - too many like Harris, AMD, Fujitsu, and Siemens were undercutting Intel's own product. The strategy was that everyone expected AMD to get a 386 license so it kept larger companies such as Hitachi and NEC from making approaches to AMD for partnership deals. Intel intended to keep AMD strung along on that assumption until the big players lost interest in AMD. Sanders took a while to figure what was going on, but finally authorized Project Longhorn when he realized he wasn't getting a 386 license. AMD initiated litigation in 1986 for breach of good faith, and greenlit Longhorn in 1989.
Reverse engineering a chip with 100,000 transistors is easy compared to the processors today with transistor counts in the billions.
Just to play the pedant, the 80386 has 275,000 transistors.