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The provenance memory model for C

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224 points HexDecOctBin | 1 comments | 30 Jun 25 09:25 UTC | HN request time: 0s | source
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RossBencina ◴[30 Jun 25 22:02 UTC] No.44428380[source]▶
After reading the fine article I'm left wondering what if you implement your own heterogeneous allocation scheme on top of malloc? (e.g. TLSF) In this case all of your objects will belong to the same malloced storage region, and you will compute object offsets using raw pointers, but I'd expect provenance to potentially treat each returned object to behave as if it were allocated from a separate disjoint storage.

I guess my question is: does this provenance model allow for recursive nesting of allocators with a separate notion of "storage" at each level?

replies(1): >>44428541 #
f33d5173 ◴[30 Jun 25 22:20 UTC] No.44428541[source]▶
The compiler knows about malloc, and hence knows that the pointer returned by malloc won't alias any other pointer. Your compiler might support some attribute to mark a function as behaving like malloc in this respect. Otherwise the compiler will be forced to assume the return value could alias any other pointer.
replies(1): >>44435458 #
1. cryptonector ◴[01 Jul 25 16:20 UTC] No.44435458[source]▶
IMO there should be attributes for declaring allocators. Or builtin functions that have the effect of marking their callers with such attributes (e.g., an `__allocated()` function to say a pointer is indeed now to be considered a pointer to a new storage allocation, with a given size and optional type, and a `__freed()` function to say that a pointer is indeed now to be considered a dangling pointer to a deallocated object.