I wrote a bounds checking patch to GCC (mentioned in a link from the article) back in 1995. It did full bounds checking of C & C++ while being compatible with existing libraries and ABIs, making it a bit more practical than Fil-C to deploy in the real world. You only had to recompile your application, if you trusted the libraries (although the bounds checking obviously didn't extend into the libraries unless you recompiled them). It didn't do the GC thing, but instead detected use after free at the point of use.

https://www.doc.ic.ac.uk/~phjk/BoundsChecking.html

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aw1621107 2 days ago | parent [-]

Interesting! How much interest did your work attract at the time?

	▲	rwmj 2 days ago \| parent [-]
		My supervisor got a few papers out of it and they are fairly widely cited even today, and as academics that was (unfortunately) the best outcome for us. The patch itself was maintained for many years, well into the mid 2000s, out of tree (actually by another person in the end), but as it never went upstream it was hard to keep doing that maintenance. There were several problems in hindsight: C programmers at the time absolutely weren't willing to accept a large slow-down in order to get bounds checking. But also we didn't optimize our changes well (or very much at all) and I'm sure we could have got the delta down a bit if we'd put the work in. The main work that dominated performance was the lookup that you have to do from the raw pointer to the fat struct that stores the pointer bounds (and you have to do this on every pointer operation). We used a splay tree for this which was clever but not very fast. A plain hash or some other data structure could have been much faster.