Any processor using pipelines suffers from self modifying code. The Intel 80486 was the first x86 chip to have a pipeline, and it was released in April 1989(!).

Any processor using pipelines suffers from self modifying code. The Intel 80486 was the first x86 chip to have a pipeline, and it was released in April 1989(!). Granted, it only had a 5 stage pipeline, so you'd only lose a few clocks each time, but modern x86 architectures have pipelines dozens of stages deep.