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Librafying of tools (cargo, rustdoc, fuzzer) #3835

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dbp
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@dbp dbp commented Oct 22, 2012

This is a continuation of #3672 because github started thinking that I wanted to merge over 300 commits (all but 2 of which were already on incoming).

@catamorphism - this passes the tests that were failing before, and passes make check (on mac, 10.7).

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brson commented Oct 23, 2012

lgtm. I ran this by the try bots today and they seemed happy. Unfortunately the windows build is broken, for unrelated reasons, and the win2 bot is down. This is the kind of thing I like the bots to be functional for.

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brson commented Oct 29, 2012

Somebody has finally started looking at our downed build machine. Hopefully it will be back up today.

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Now that the bots are all happy again, I'm running a rebased version of this on try.

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try passes on linux, mac, and freebsd. Hoping nothing is secretly broken on Windows (the try bot doesn't work on Windows, for unrelated reasons); merged to incoming. Thanks for your patience, @dbp !

bors pushed a commit to rust-lang-ci/rust that referenced this pull request May 15, 2021
RalfJung pushed a commit to RalfJung/rust that referenced this pull request Aug 30, 2024
…r=RalfJung

Avoid extra copy by using `retain_mut` and moving the deletion into the closure

Fixes the FIXME introduced in rust-lang#3833. Thanks to `@dmitrii-ubskii` for the idea 🙂
RalfJung pushed a commit to RalfJung/rust that referenced this pull request Aug 30, 2024
Follow-up on rust-lang#3833 and rust-lang#3835. In these PRs, the TB GC was fixed to no
longer cause a stack overflow. One test that motivated it was the test
`fill::horizontal_line` in `tiny_skia`. But not causing stack overflows
was not a large improvents, since it did not fix the fundamental issue:
The tree was too large. The test now ran, but it required gigabytes of
memory and hours of time, whereas it finishes within seconds in Stacked
Borrows.

The problem in that test was that it used [`slice::chunked`](https://doc.rust-lang.org/std/primitive.slice.html#method.chunks) to iterate
a slice in chunks. That iterator is written to reborrow at each call to
`next`, which creates a linear tree with a bunch of intermediary nodes,
which also fragments the `RangeMap` for that allocation.

The solution is to now compact the tree, so that these interior nodes
are removed. Care is taken to not remove nodes that are protected, or
that otherwise restrict their children.
RalfJung pushed a commit to RalfJung/rust that referenced this pull request Aug 30, 2024
…e-gc, r=RalfJung

Make Tree Borrows Provenance GC compact the tree

Follow-up on rust-lang#3833 and rust-lang#3835. In these PRs, the TB GC was fixed to no longer cause a stack overflow. One test that motivated it was the test `fill::horizontal_line` in [`tiny-skia`](https://github.com/RazrFalcon/tiny-skia). But not causing stack overflows was not a large improvents, since it did not fix the fundamental issue: The tree was too large. The test now ran, but it required gigabytes of memory and hours of time (only for it to be OOM-killed 🤬), whereas it finishes within 24 seconds in Stacked Borrows. With this merged, it finishes in about 40 seconds under TB.

The problem in that test was that it used [`slice::chunked`](https://doc.rust-lang.org/std/primitive.slice.html#method.chunks) to iterate a slice in chunks. That iterator is written to reborrow at each call to `next`, which creates a linear tree with a bunch of intermediary nodes, which also fragments the `RangeMap` for that allocation.

The solution is to now compact the tree, so that these interior nodes are removed. Care is taken to not remove nodes that are protected, or that otherwise restrict their children.

I am currently only 99% sure that this is sound, and I do also think that this could compact even more. So `@Vanille-N` please also have a look at whether I got the compacting logic right.

For a more visual comparison, [here is a gist](https://gist.github.com/JoJoDeveloping/ae4a7f7c29335a4c233ef42d2f267b01) of what the tree looks like at one point during that test, with and without compacting.

This new GC requires a different iteration order during accesses (since the current one can make the error messages non-deterministic), so it is rebased on top of rust-lang#3843 and requires that PR to be merged first.
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3 participants