Assorted improvements for `rustc_middle::mir::traversal`
r? `@cjgillot`
I'm not _entirely_ sure about all changes, although I do like all of them. If you'd like I can drop some commits. Best reviewed on a commit-by-commit basis, I think, since they are fairly isolated.
rustdoc: speed up processing of cross-crate fns to fix a perf regression
* The first commit doesn't affect perf but get's rid of a `.clone()` and a bunch of lines of code. I can drop it if you'd like me to
* The second commit, *“reduce the amount of `asyncness` query executions”*, addresses the perf regression introduced in #116084
r? `@ghost`
Prototype using const generic for simd_shuffle IDX array
cc https://github.com/rust-lang/rust/issues/85229
r? `@workingjubilee` on the design
TLDR: there is now a `fn simd_shuffle_generic<T, U, const IDX: &'static [u32]>(x: T, y: T) -> U;` intrinsic that allows replacing
```rust
simd_shuffle(a, b, const { stuff })
```
with
```rust
simd_shuffle_generic::<_, _, {&stuff}>(a, b)
```
which makes the compiler implementations much simpler, if we manage to at some point eliminate `simd_shuffle`.
There are some issues with this today though (can't do math without bubbling it up in the generic arguments). With this change, we can start porting the simple cases and get better data on the others.
More fixes for running the test suite on a bare metal target
This PR adds more fixes needed to run the test suite on bare metal targets (in this case, without unwinding and with static relocations). There is no CI job exercising tests without unwinds, but I can confirm this worked in Ferrocene's CI.
ci: upgrade to crosstool-ng 1.26.0
This PR upgrades our builders from crosstool-ng 1.25.0 to 1.26.0. Except for LoongArch64 and RISC-V 64, which have minor version upgrades, other architectures have not changed.
Clippy backport: Move needless_raw_string_hashes to pedantic
Really small backport this time. Context: https://github.com/rust-lang/rust-clippy/pull/11415#issuecomment-1739880932
I'd rather get this in 1.74 than waiting another release cycle.
r? `@Manishearth`
cc `@Mark-Simulacrum` This should be merged before beta is branched tomorrow.
Update windows ffi bindings
Bump `windows-bindgen` to version 0.51.1. This brings with it some changes to the generated FFI bindings, but little that affects the code.
One change that does have more of an impact is `SOCKET` being `usize` instead of either `u64` or `u32` (as is used in std's public `SOCKET` type). However, it's now easy enough to abstract over that difference.
Finally I added a few new bindings that are likely to be used in pending PRs, mostly to make sure they're ok with the new metadata.
r? libs
Implement a global value numbering MIR optimization
The aim of this pass is to avoid repeated computations by reusing past assignments. It is based on an analysis of SSA locals, in order to perform a restricted form of common subexpression elimination.
By opportunity, this pass allows for some simplifications by combining assignments. For instance, this pass could be able to see through projections of aggregates to directly reuse the aggregate field (not in this PR).
We handle references by assigning a different "provenance" index to each `Ref`/`AddressOf` rvalue. This ensure that we do not spuriously merge borrows that should not be merged. Meanwhile, we consider all the derefs of an immutable reference to a freeze type to give the same value:
```rust
_a = *_b // _b is &Freeze
_c = *_b // replaced by _c = _a
```
