It is claimed this AI-automated feat was about a thousand times faster than a human team could have finished a comparable CPU design.
While the resulting AI-designed CPU performed approximately on par with an i486, it is not as if any mortal could knock up something better that fast.
Training consisted of observing a series of CPU inputs and outputs. The scientists generated a Binary Speculation Diagram (BSD) from this I/O. They used principles of Monte Carlo-based expansion and Boolean functions to hone the accuracy and efficiency of the AI-based CPU design.
The boffins explained that the CPU design was formed from only external input-output observations instead of formal program code. It boasted an impressive 99.99999999999% accuracy.
The taped-out RISC-V32IA instruction set CPU was fabricated at 65nm and could run at up to 300 MHz. It validated its functionality by running the Linux (kernel 5.15) operating system and SPEC CINT 2000 on the AI-generated CPU. In Drystone benchmarks, the AI-generated CPU performed on par with an i486.
This makes it a bit faster than an Acorn Archimedes A3010 in the same test. The boffins seem quite proud that their generated BSD "discovered the von Neumann architecture from scratch."