sandsifter VS lazarus

This has some background.

sandsifter

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 good part of the last two years working on a fuzzer that's discovered thousands of bugs in various popular x86 decoders[2][3].

[1]: https://github.com/xoreaxeaxeax/sandsifter

[2]: https://github.com/trailofbits/mishegos

[3]: https://ww.easychair.org/publications/preprint_download/1LHr

Idea:

If any assembler/disassembler author/team out there wants to produce an assembler/disassembler which is authoritative (difficult to do on x86, because there are so many different possible combinations of instruction encoding, https://github.com/xoreaxeaxeax/sandsifter : "Typically, several million undocumented instructions on your processor will be found, but these generally fall into a small number of different groups.") -- then what they'd do is to create a third program -- which "pits" the output of Assembler A vs. Assembler B, Disassembler A vs. Disassembler B...

That is, between any two assemblers (for the same CPU architecture/instruction set), or any two disassemblers, where are the anomalies?

If we think about an assembler as a simple function, y=f(x), that is, I give it a string of ascii bytes as input (x), and I get a string (1..n) binary bytes as output (y),

The most "funny" disassembler I have ever seen in pascal/delphi is the one from cheat engine...

https://github.com/cheat-engine/cheat-engine/blob/master/Che...

That one unit has more than 16000 LOC, its basically one huge case statement where each opcode is handled separately... super simple but certainly not DRY (don't repeat yourself). But I guess its one of those cases which you should avoid writing DRY code.

In the same manner is the fpdebug-disassembler from the free pascal team, I found that disassembler one of the most elegant one.

https://github.com/alrieckert/lazarus/blob/master/components...

It has some minor errors in the Rex decoding though, if I remember correctly....