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Hindsight: Reversible Computing

Posted by Hemos on from the step-back-into-the-past dept.

One of the more interesting tech pieces that came out this week has been Hindsight [PDF]. Hindsight is made by Virtutech and is billed as the "the first complete, general-purpose tool for reverse execution and debugging of arbitrary electronic systems." The demos were received extremely well and it just looks cool.

6 of 178 comments (clear)

  1. UI by GigsVT · · Score: 5, Interesting

    They say the way they accomplish this is running the program in some sort of sandbox and taking checkpoints every so often and then when you step back, it actually runs forward from the closest checkpoint and stops one instruction short.

    My question is how UI interactions are handled. If the execution between the checkpoint and current-1 instruction includes a UI interaction, it might be very confusing to the programmer to know what or how many UI interactions need to be carried out to accomplish the backstep.

    --
    I've had enough abrasive sigs. Kittens are cute and fuzzy.
  2. Too good to be true... by Leadhyena · · Score: 5, Insightful
    I can see how this software can come in real handy, but it won't work in every situation. It states in TFA that Hindsight doesn't do the naive approach of recording every instrction, but rather takes snapshots and tries to fill in the gaps. There are many types of calculations out there (think The Game of Life or other CAs) that by their nature cannot be reversed, so all of those states would have to be stored or it would be mathematically impossible to calculate the reverse steps.

    Therefore, I can't see their approach being foolproof, and the over-obvious advertisement (this is what normal debugging toolbars look like, but they don't have a nifty step-one-back feature) seems too bright to be withot caveat. At $5,000 a seat I'd say buyer beware.

  3. Re:But what about external events by tesmako · · Score: 5, Informative

    Since it is based on the whole-system simulator Simics -- Yes, it does assume that the app runs in isolation, since all external stuff is just simics simulations.

  4. Not by a decade. by Murmer · · Score: 5, Interesting
    This technology has existed, in GPL form, for ten years. It's just had exactly zero uptake.

    I read this usenet post every now and then when I'm trying to fix something, and it makes me want to cry every time I do.

    --
    Mike Hoye
  5. Reversible Computing != Reversible Execution by Anonymous Coward · · Score: 5, Informative

    Reversible computing is a way of computing without (permenantly) consuming energy. Look it up if you're not familiar, because it's pretty interesting.

    Anyway, the headline is misleading.

  6. Elephants never forget by same_old_story · · Score: 5, Interesting
    John McCarthy has been talking about giving programming langues the notion of time for quite some time (no pun intended).

    In this paper, he proposes the Elephant language that can refer to the past in computer programs.

    Pretty cool stuff!