Hacker News Reader

You are correct for complex CPUs with actual ROB with hundreds of entries. For those micro-architecture, LDM is not particularly stressful. I was focused on the micro-controller case, with much simpler pipelines. LDM is one of the instructions causing the pipeline a lot more headaches than it's worth.

View on HN

Microcontrollers don't need additional ports either. Take a look a the ARMv7-M status/control register. It has a few bits of state to allow ldm, stm, and if-then to be resumed in-place.

At that scale, those mechanisms aren't micro-coded, they are state-machined. You just have to restore the state machine.

Reply on news.ycombinator.com