[jasonwatkinspdx]

Yes, it's been looked at. If you wanna skim the research use "Eager Execution" and "Disjoint Eager Execution" as jumping off points.

It doesn't require duplicating everything. You just need to add some additional bookkeeping of dependencies and what to retire vs kill at the end of the pipeline.

In practice branch predictors are so good that speculating off the "spine" of most likely path just isn't worth it.

In fact there were a lot of interesting microarchitectural ideas from the late 90s to early 00s that just ended up being moot because the combination of OoO speculation, branch predictors, and big caches proved so effective.

[adastra22]

I think you’re missing the context: that good branch prediction is what causes these security holes. “Wasteful” multi path execution is a security feature.

[jasonwatkinspdx]

No, security vulnerabilities are orthogonal. There's nothing about branch prediction that necessitates leaking information, as demonstrated by the fixes shipped in current processors.