Rustup #3336
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Rustup #3336
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Seems wise, since it shouldn't proceed in that case.
…isDenton Enable CMPXCHG16B, SSE3, SAHF/LAHF and 128-bit Atomics (in nightly) in Windows x64 As Rust plans to set Windows 10 as the minimum supported OS for target x86_64-pc-windows-msvc, I have added the cmpxchg16b and sse3 feature. Windows 10 requires CMPXCHG16B, LAHF/SAHF, and PrefetchW as stated in the requirements [here](https://download.microsoft.com/download/c/1/5/c150e1ca-4a55-4a7e-94c5-bfc8c2e785c5/Windows%2010%20Minimum%20Hardware%20Requirements.pdf). Furthermore, CPUs that meet these requirements also have SSE3 ([see](https://walbourn.github.io/directxmath-sse3-and-ssse3/))
pattern_analysis: rework how we hide empty private fields
Consider this:
```rust
mod foo {
pub struct Bar {
pub a: bool,
b: !,
}
}
fn match_a_bar(bar: foo::Bar) -> bool {
match bar {
Bar { a, .. } => a,
}
}
```
Because the field `b` is private, matches outside the module are not allowed to observe the fact that `Bar` is empty. In particular `match bar {}` is valid within the module `foo` but an error outside (assuming `exhaustive_patterns`).
We currently handle this by hiding the field `b` when it's both private and empty. This means that the pattern `Bar { a, .. }` is lowered to `Bar(a, _)` if we're inside of `foo` and to `Bar(a)` outside. This involves a bit of a dance to keep field indices straight. But most importantly this makes pattern lowering depend on the module.
In this PR, I instead do nothing special when lowering. Only during analysis do we track whether a place must be skipped.
r? `@compiler-errors`
Skip unnecessary comparison with half-open range patterns This is the last remaining detail in the implementation of half-open range patterns. Until now, a half-open range pattern like `10..` was converted to `10..T::MAX` before lowering to MIR, which generated an extra pointless comparison. With this PR we don't generate it.
Use volatile access instead of `#[used]` for `on_tls_callback` The first commit adds a volatile load of `p_thread_callback` when registering a dtor so that the compiler knows if the callback is used or not. I don't believe the added volatile instruction is otherwise significant in the context. In my testing using the volatile load allowed the compiler to correctly reason about whether `on_tls_callback` is used or not, allowing it to be omitted entirely in some cases. Admittedly it usually is used due to `Thread` but that can be avoided (e.g. in DLLs or with custom entry points that avoid the offending APIs). Ideally this would be something the compiler could help a bit more with so we didn't have to use tricks like `#[used]` or volatile. But alas. I also used this as an opportunity to clean up the `unused` lints which I don't think serve a purpose any more. The second commit removes the volatile load of `_tls_used` with `#cfg[target_thread_local]` because `#[thread_local]` already implies it. And if it ever didn't then `#[thread_local]` would be broken when there aren't any dtors.
…ebank Count stashed errors again Stashed diagnostics are such a pain. Their "might be emitted, might not" semantics messes with lots of things. #120828 and #121206 made some big changes to how they work, improving some things, but still leaving some problems, as seen by the issues caused by #121206. This PR aims to fix all of them by restricting them in a way that eliminates the "might be emitted, might not" semantics while still allowing 98% of their benefit. Details in the individual commit logs. r? `@oli-obk`
Emitter cleanups Some cleanups I made when reading emitter code. In particular, `HumanEmitter` and `JsonEmitter` have gone from three constructors to one. r? `@oli-obk`
Rollup of 7 pull requests Successful merges: - #119748 (Increase visibility of `join_path` and `split_paths`) - #120820 (Enable CMPXCHG16B, SSE3, SAHF/LAHF and 128-bit Atomics (in nightly) in Windows x64) - #121000 (pattern_analysis: rework how we hide empty private fields) - #121376 (Skip unnecessary comparison with half-open range patterns) - #121596 (Use volatile access instead of `#[used]` for `on_tls_callback`) - #121669 (Count stashed errors again) - #121783 (Emitter cleanups) r? `@ghost` `@rustbot` modify labels: rollup
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@bors r+ |
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☀️ Test successful - checks-actions |
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Also add regression test for rust-lang/rust#121508.