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Speculating the entire x86-64 instruction set in seconds with one weird trick

blog.can.ac Essays & writing Essays & articles Hardware & electronics Candidate
Screenshot of blog.can.ac captured 2026-07-20
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Resurfaced independently across 2 calendar years, with breakout response in 2 of them.

submissions
6
submitters
6
observed span
2021–2024
peak thread · 65 comments
208 pts
latest 20+ return · 2024-05-14
104 pts

Submission timeline

2007–2026

One slot for every year since HN launched. Height is that year's peak points; orange marks a 100+ point or 50+ comment breakout. Select a bar to open its strongest thread.

First comments on top threads

HN comment order

This is a really clever technique! I was impressed by sandsifter[1] when it originally came out, and this seems an awful lot faster and less prone to false negatives (since it's purely speculative and doesn't require sandsifter's `#PF` hack). At the risk of unwarranted self-promotion: the other side of this equation is fidelity in software instruction set decoders. x86's massive size and layers of historical complexity make it among the most difficult instruction formats to accurately decode; I've spent a…

Could they do this with x86-16?

The first top-level comment from each of the four biggest threads, in HN’s own order. Excerpts are shortened; open a comment for full context.

Breakout years
2

100+ points or 50+ comments

Total points
330

reference only — not used in Hall rules or ranking

Total comments
69

reference only — not used in Hall rules or ranking

Every submission