Fix races conditions with `SyntaxContext` decoding
This changes `SyntaxContext` decoding to work with concurrent decoding. The `remapped_ctxts` field now only stores `SyntaxContext` which have completed decoding, while the new `decoding` and `local_in_progress` keeps track of `SyntaxContext`s which are in process of being decoding and on which threads.
This fixes 2 issues with the current implementation. It can return an `SyntaxContext` which contains dummy data if another thread starts decoding before the first one has completely finished. Multiple threads could also allocate multiple `SyntaxContext`s for the same `raw_id`.
[rustc_data_structures][base_n][perf] Remove unnecessary utf8 check.
Since all output characters taken from `BASE_64` are valid UTF8 chars there is no need to waste cycles on validation.
Even though it's obviously a perf win, I've also used a [benchmark](https://gist.github.com/ttsugriy/e1e63c07927d8f31e71695a9c617bbf3) on M1 MacBook Air with following results:
```
Running benches/base_n_benchmark.rs (target/release/deps/base_n_benchmark-825fe5895b5c2693)
push_str/old time: [14.670 µs 14.852 µs 15.074 µs]
Found 11 outliers among 100 measurements (11.00%)
4 (4.00%) high mild
7 (7.00%) high severe
push_str/new time: [12.573 µs 12.674 µs 12.801 µs]
Found 11 outliers among 100 measurements (11.00%)
7 (7.00%) high mild
4 (4.00%) high severe
```
It lints against features that are inteded to be internal to the
compiler and standard library. Implements MCP #596.
We allow `internal_features` in the standard library and compiler as those
use many features and this _is_ the standard library from the "internal to the compiler and
standard library" after all.
Marking some features as internal wasn't exactly the most scientific approach, I just marked some
mostly obvious features. While there is a categorization in the macro,
it's not very well upheld (should probably be fixed in another PR).
We always pass `-Ainternal_features` in the testsuite
About 400 UI tests and several other tests use internal features.
Instead of throwing the attribute on each one, just always allow them.
There's nothing wrong with testing internal features^^
Since all output characters taken from `BASE_64` are valid UTF8 chars
there is no need to waste cycles on validation.
Even though it's obviously a perf win, I've also used a [benchmark](https://gist.github.com/ttsugriy/e1e63c07927d8f31e71695a9c617bbf3)
on M1 MacBook Air with following results:
```
Running benches/base_n_benchmark.rs (target/release/deps/base_n_benchmark-825fe5895b5c2693)
push_str/old time: [14.670 µs 14.852 µs 15.074 µs]
Performance has regressed.
Found 11 outliers among 100 measurements (11.00%)
4 (4.00%) high mild
7 (7.00%) high severe
push_str/new time: [12.573 µs 12.674 µs 12.801 µs]
Performance has regressed.
Found 11 outliers among 100 measurements (11.00%)
7 (7.00%) high mild
4 (4.00%) high severe
```
[rustc_data_structures][perf] Simplify base_n::push_str.
This minor change removes the need to reverse resulting digits. Since reverse is O(|digit_num|) but bounded by 128, it's unlikely to be a noticeable in practice. At the same time, this code is also a 1 line shorter, so combined with tiny perf win, why not?
I ran https://gist.github.com/ttsugriy/ed14860ef597ab315d4129d5f8adb191 on M1 macbook air and got a small improvement
```
Running benches/base_n_benchmark.rs (target/release/deps/base_n_benchmark-825fe5895b5c2693)
push_str/old time: [14.180 µs 14.313 µs 14.462 µs]
Performance has improved.
Found 5 outliers among 100 measurements (5.00%)
4 (4.00%) high mild
1 (1.00%) high severe
push_str/new time: [13.741 µs 13.839 µs 13.973 µs]
Performance has improved.
Found 8 outliers among 100 measurements (8.00%)
3 (3.00%) high mild
5 (5.00%) high severe
```
[rustc_data_structures] Simplify SortedMap::insert.
It looks like current usage of `swap` is aimed at achieving what `std::mem::replace` does but more concisely and idiomatically.
This minor change removes the need to reverse resulting digits.
Since reverse is O(|digit_num|) but bounded by 128, it's unlikely
to be a noticeable in practice. At the same time, this code is
also a 1 line shorter, so combined with tiny perf win, why not?
I ran https://gist.github.com/ttsugriy/ed14860ef597ab315d4129d5f8adb191
on M1 macbook air and got a small improvement
```
Running benches/base_n_benchmark.rs (target/release/deps/base_n_benchmark-825fe5895b5c2693)
push_str/old time: [14.180 µs 14.313 µs 14.462 µs]
Performance has improved.
Found 5 outliers among 100 measurements (5.00%)
4 (4.00%) high mild
1 (1.00%) high severe
push_str/new time: [13.741 µs 13.839 µs 13.973 µs]
Performance has improved.
Found 8 outliers among 100 measurements (8.00%)
3 (3.00%) high mild
5 (5.00%) high severe
```
It no longer has any uses. If it's needed in the future, it can be
easily reinstated. Or a crate such as `smallstr` can be used, much like
we use `smallvec`.
Removed unnecessary &String -> &str, now that &String implements StableOrd as well
Applied a few nits suggested by lcnr to PR #110040 (nits can be found [here](https://github.com/rust-lang/rust/pull/110040#pullrequestreview-1469452191).)
Making a new PR because the old one was already merged, and given that this just applies changes that were already suggested, reviewing it should be fairly open-and-shut.
Don't leak the function that is called on drop
It probably wasn't causing problems anyway, but still, a `// this leaks, please don't pass anything that owns memory` is not sustainable.
I could implement a version which does not require `Option`, but it would require `unsafe`, at which point it's probably not worth it.
Use `Option::is_some_and` and `Result::is_ok_and` in the compiler
`.is_some_and(..)`/`.is_ok_and(..)` replace `.map_or(false, ..)` and `.map(..).unwrap_or(false)`, making the code more readable.
This PR is a sibling of https://github.com/rust-lang/rust/pull/111873#issuecomment-1561316515
Preprocess and cache dominator tree
Preprocessing dominators has a very strong effect for https://github.com/rust-lang/rust/pull/111344.
That pass checks that assignments dominate their uses repeatedly. Using the unprocessed dominator tree caused a quadratic runtime (number of bbs x depth of the dominator tree).
This PR also caches the dominator tree and the pre-processed dominators in the MIR cfg cache.
Rebase of https://github.com/rust-lang/rust/pull/107157
cc `@tmiasko`
Process current bucket instead of parent's bucket when starting loop for dominators.
The linked paper by Georgiadis suggests in §2.2.3 to process `bucket[w]` when beginning the loop, instead of `bucket[parent[w]]` when finishing it.
In the test case, we correctly computed `idom[2] = 0` and `sdom[3] = 1`, but the algorithm returned `idom[3] = 1`, instead of the correct value 0, because of the path 0-7-2-3.
This provoked LLVM ICE in https://github.com/rust-lang/rust/pull/111061#issuecomment-1546912112. LLVM checks that SSA assignments dominate uses using its own implementation of Lengauer-Tarjan, and saw case where rustc was breaking the dominance property.
r? `@Mark-Simulacrum`
