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Comment by artemonster | Hacker News Reader

I wonder how much potential optimisation there is if we entirely drop pointer nonsense.

Are you talking about dropping pointers as a programmer-facing programming language concept (in which case you might find Hylo and similar languages interesting), or dropping pointers from everything - programming languages, their implementations, compilers, etc. (in which case I'm not sure that's even possible)?

Only the first one. Ofc under the hood they will stay, but I think its time to ditch random access model and pull fetching and concept of time closer to programmer

This is basically what many functional programming languages do. This always came with plausibly sounding claims that this allows so much better optimizations that this soon will surpass imperative programs in performance, but this never materialized (it still did not - even though Rust fans now adopted this claim, it still isn't quite true). Also control over explicit memory layout is still more important.

Gah, can't believe I forgot about functional programming languages here :(

> even though Rust fans now adopted this claim

Did they? Rust's references seem pretty pointer-like to me on the scale of "has pointers" to "pointers have been entirely removed from the language".

(Obviously Rust has actual pointers as well, but since usefully using them requires unsafe I assume they're out of scope here)

What I meant is that Rust has stricter aliasing rules which make some optimization possible without extra annotations, but this is balanced out by many other issues.

Sure, but I think the presence/absence of aliasing is different from what GP was wondering/asking about, which was the removal of pointers from the programmer-facing model.

For a system programming language the right solution is to properly track aliasing information in the type system as done in Rust.

Aliasing issues is just yet another instance of C/C++ inferiority holding the industry back. C could've learnt from Fortran, but we ended up with the language we have...

For systems programming the correct way is to have explicit annotations so you can tell the compiler things like:

    void foo(void *a, void *b, int n) {
        assume_aligned(a, 16);
        assume_stride(a, 16);
        assume_distinct(a, b);
        ... go and vectorize!
    }

LOL, nope. Those annotations must be part of the type system (e.g. `&mut T` in Rust) and must be checked by the compiler (the borrow checker). The language can provide escape hatches like `unsafe`, but they should be rarely used. Without it you get a fragile footgunny mess.

Just look at the utter failure of `restrict`. It was so rarely used in C that it took several years of constant nagging from Rust developers to iron out various bugs in compilers caused by it.

Does make me wonder what restrict-related bugs will be (have been?) uncovered in GCC, if any. Or whether the GCC devs saw what LLVM went through and decided to try to address any issues preemptively.

gcc has had restrict for 25 years I think. I would hope most bugs have been squashed by now.

Possibly? LLVM had been around for a while as well but Rust still ended up running into aliasing-related optimizer bugs.

Now that I think about it some more, perhaps gfortran might be a differentiating factor? Not familiar enough with Fortran to guess as to how much it would exercise aliasing-related optimizations, though.

I think Fortran function arguments are assumed not to alias. I'm not sure if it matches C restrict semantics though.

Yeah, that's why I was wondering whether GCC might have shaken out its aliasing bugs. Sibling seems to recall otherwise, though.

IIRC at least one of the `restrict` bugs found by Rust was reproduced on both LLVM and GCC.

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