Do not promote union field accesses
r? @eddyb
technically a breaking change, but the code errored on the previous stable and produces UB + a warning on the current stable. I don't think we need a crater run in that case.
OOM handling changes
As discussed in https://github.com/rust-lang/rust/issues/49668#issuecomment-384893456 and subsequent.
This does have codegen implications. Even without the hooks, and with a handler that ignores the arguments, the compiler doesn't eliminate calling `rust_oom` with the `Layout`. Even if it managed to eliminate that, with the hooks, I don't know if the compiler would be able to figure out it can skip it if the hook is never set.
A couple implementation notes:
- I went with explicit enums rather than bools because it makes it clearer in callers what is being requested.
- I didn't know what `feature` to put the hook setting functions behind. (and surprisingly, the compile went through without any annotation on the functions)
- There's probably some bikeshedding to do on the naming.
Cc: @Simonsapin, @sfackler
As discussed in
https://github.com/rust-lang/rust/issues/49668#issuecomment-384893456
and subsequent, there are use-cases where the OOM handler needs to know
the size of the allocation that failed. The alignment might also be a
cause for allocation failure, so providing it as well can be useful.
Add simd math intrinsics and gather/scatter
This PR adds simd math intrinsics for floating-point vectors (sqrt, sin, cos, pow, exp, log, fma, abs, etc.) and the generic simd gather/scatter intrinsics.
Fix issue #50811 (`NaN > NaN` was true).
Fix#50811
Make sure the float comparison output is consistent with the expected behavior when NaN is involved.
----
Note: This PR is a **BREAKING CHANGE**. If you have used `>` or `>=` to compare floats, and make the result as the length of a fixed array type, like:
```rust
use std::f64::NAN;
let x: [u8; (NAN > NAN) as usize] = [1];
```
then the code will no longer compile. Previously, all float comparison involving NaN will just return "Greater", i.e. `NAN > NAN` would wrongly return `true` during const evaluation. If you need to retain the old behavior (why), you may replace `a > b` with `a != a || b != b || a > b`.
rustc: introduce {ast,hir}::AnonConst to consolidate so-called "embedded constants".
Previously, constants in array lengths and enum variant discriminants were "merely an expression", and had no separate ID for, e.g. type-checking or const-eval, instead reusing the expression's.
That complicated code working with bodies, because such constants were the only special case where the "owner" of the body wasn't the HIR parent, but rather the same node as the body itself.
Also, if the body happened to be a closure, we had no way to allocate a `DefId` for both the constant *and* the closure, leading to *several* bugs (mostly ICEs where type errors were expected).
This PR rectifies the situation by adding another (`{ast,hir}::AnonConst`) node around every such constant. Also, const generics are expected to rely on the new `AnonConst` nodes, as well (cc @varkor).
* fixes#48838
* fixes#50600
* fixes#50688
* fixes#50689
* obsoletes #50623
r? @nikomatsakis
Implement [T]::align_to
Note that this PR deviates from what is accepted by RFC slightly by making `align_offset` to return an offset in elements, rather than bytes. This is necessary to sanely support `[T]::align_to` and also simply makes more sense™. The caveat is that trying to align a pointer of ZST is now an equivalent to `is_aligned` check, rather than anything else (as no number of ZST elements will align a misaligned ZST pointer).
It also implements the `align_to` slightly differently than proposed in the RFC to properly handle cases where size of T and U aren’t co-prime.
Furthermore, a promise is made that the slice containing `U`s will be as large as possible (contrary to the RFC) – otherwise the function is quite useless.
The implementation uses quite a few underhanded tricks and takes advantage of the fact that alignment is a power-of-two quite heavily to optimise the machine code down to something that results in as few known-expensive instructions as possible. Currently calling `ptr.align_offset` with an unknown-at-compile-time `align` results in code that has just a single "expensive" modulo operation; the rest is "cheap" arithmetic and bitwise ops.
cc https://github.com/rust-lang/rust/issues/44488 @oli-obk
As mentioned in the commit message for align_offset, many thanks go to Chris McDonald.
Implement edition hygiene for keywords
Determine "keywordness" of an identifier in its hygienic context.
cc https://github.com/rust-lang/rust/pull/49611
I've resurrected `proc` as an Edition-2015-only keyword for testing purposes, but it should probably be buried again. EDIT: `proc` is removed again.
stop considering location when computing outlives relationships
This doesn't (yet?) use SEME regions, but it does ignore the location for outlives constraints. This makes (I believe) NLL significantly faster -- but we should do some benchmarks. It regresses the "get-default" family of use cases for NLL, which is a shame, but keeps the other benefits, and thus represents a decent step forward.
r? @pnkfelix
This is necessary if we want to implement `[T]::align_to` and is more
useful in general.
This implementation effort has begun during the All Hands and represents
a month of my futile efforts to do any sort of maths. Luckily, I
found the very very nice Chris McDonald (cjm) on IRC who figured out the
core formulas for me! All the thanks for existence of this PR go to
them!
Anyway… Those formulas were mangled by yours truly into the arcane forms
you see here to squeeze out the best assembly possible on most of the
modern architectures (x86 and ARM were evaluated in practice). I mean,
just look at it: *one actual* modulo operation and everything else is
just the cheap single cycle ops! Admitedly, the naive solution might be
faster in some common scenarios, but this code absolutely butchers the
naive solution on the worst case scenario.
Alas, the result of this arcane magic also means that the code pretty
heavily relies on the preconditions holding true and breaking those
preconditions will unleash the UB-est of all UBs! So don’t.
Rollup of 17 pull requests
Successful merges:
- #50170 (Implement From for more types on Cow)
- #50638 (Don't unconditionally set CLOEXEC twice on every fd we open on Linux)
- #50656 (Fix `fn main() -> impl Trait` for non-`Termination` trait)
- #50669 (rustdoc: deprecate `#![doc(passes, plugins, no_default_passes)]`)
- #50726 (read2: Use inner function instead of closure)
- #50728 (Fix rustdoc panic with `impl Trait` in type parameters)
- #50736 (env: remove unwrap in examples in favor of try op)
- #50740 (Remove LazyBTreeMap.)
- #50752 (Add missing error codes in libsyntax-ext asm)
- #50779 (Make mutable_noalias and arg_align_attributes be tracked)
- #50787 (Fix run-make wasm tests)
- #50788 (Fix an ICE when casting a nonexistent const)
- #50789 (Ensure libraries built in stage0 have unique metadata)
- #50793 (tidy: Add a check for empty UI test files)
- #50797 (fix a typo in signed-integer::from_str_radix())
- #50808 (Stabilize num::NonZeroU*)
- #50809 (GitHub: Stop treating Cargo.lock as a generated file.)
Failed merges:
