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A simplified model of Fil-C

207 points by aw1621107

by avadodin

0 subcomment

It could be a fun exercise to add invisicaps to something like chibicc/slimcc.
It leaves room for experimentation with reference counting and variations on the invisible capability system which could provide memory savings at the expense of some extra indirection.

by hsaliak

0 subcomment

I made https://github.com/hsaliak/filc-bazel-template bazel target for people who may want to use these two together to make hermetic builds with it.

by quotemstr

2 subcomments

Fil-C is not memory safe under data races. The capability and pointer values tear under assignment, which means that if you get the wrong thread interleaving, you can access an object through a wrong pointer, causing arbitrary program misbehavior.
This limitation would be fine if Fil-C proponents (including its author) didn't try to shout down anyone pointing out this limitation.

by teo_zero

0 subcomment

Could anyone understand what this sentence means?
> Upon freeing an unreachable AllocationRecord, call filc_free on it.
I think the intention was to say: before freeing an unreachable AR, free the memory pointed to by its visible_bytes and invisible_bytes fields.

by whatsakandr

12 subcomments

Fil-C is one of the most underrated projects I've ever seen. All this "rewrite it in rust for safety" just sounds stupid when you can compile your C program completely memory safe.

by vzaliva

2 subcomments

This is yet another variant of the "fat pointers" technique, which has been implemented and rejected many times due to either insufficient security guarantees, inability to cross non-fat ABI boundaries, or the overhead it introduces.