add x86-sse2 (32bit) ABI that requires SSE2 target feature

This is the first commit of rust-lang#135408:

The primary goal of this is to make SSE2 required for our i686 targets (at least for the ones that use Pentium 4 as their baseline), to ensure they cannot be affected by rust-lang#114479. This has been MCPd in rust-lang/compiler-team#808, and is tracked in rust-lang#133611.

We do this by defining a new ABI that these targets select, and making SSE2 required by the ABI (that's the first commit). That's kind of a hack, but it is the easiest way to make a target feature required via the target spec. In a follow-up change (rust-lang#135408), we can actually make use of SSE2 for the ABI, but that is running into some infrastructure issues.

r? `@workingjubilee`

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add x86-sse2 (32bit) ABI that requires SSE2 target feature

This is the first commit of rust-lang#135408:

The primary goal of this is to make SSE2 required for our i686 targets (at least for the ones that use Pentium 4 as their baseline), to ensure they cannot be affected by rust-lang#114479. This has been MCPd in rust-lang/compiler-team#808, and is tracked in rust-lang#133611.

We do this by defining a new ABI that these targets select, and making SSE2 required by the ABI (that's the first commit). That's kind of a hack, but it is the easiest way to make a target feature required via the target spec. In a follow-up change (rust-lang#135408), we can actually make use of SSE2 for the ABI, but that is running into some infrastructure issues.

r? `@workingjubilee`

try-job: aarch64-apple
try-job: aarch64-gnu
try-job: aarch64-gnu-debug
try-job: test-various
try-job: x86_64-gnu-nopt
try-job: dist-i586-gnu-i586-i686-musl

add x86-sse2 (32bit) ABI that requires SSE2 target feature

This is the first commit of rust-lang#135408:

The primary goal of this is to make SSE2 required for our i686 targets (at least for the ones that use Pentium 4 as their baseline), to ensure they cannot be affected by rust-lang#114479. This has been MCPd in rust-lang/compiler-team#808, and is tracked in rust-lang#133611.

We do this by defining a new ABI that these targets select, and making SSE2 required by the ABI (that's the first commit). That's kind of a hack, but it is the easiest way to make a target feature required via the target spec. In a follow-up change (rust-lang#135408), we can actually make use of SSE2 for the ABI, but that is running into some infrastructure issues.

r? `@workingjubilee`

try-job: aarch64-apple
try-job: aarch64-gnu
try-job: aarch64-gnu-debug
try-job: test-various
try-job: x86_64-gnu-nopt
try-job: dist-i586-gnu-i586-i686-musl

add x86-sse2 (32bit) ABI that requires SSE2 target feature

This is the first commit of rust-lang#135408:

The primary goal of this is to make SSE2 required for our i686 targets (at least for the ones that use Pentium 4 as their baseline), to ensure they cannot be affected by rust-lang#114479. This has been MCPd in rust-lang/compiler-team#808, and is tracked in rust-lang#133611.

We do this by defining a new ABI that these targets select, and making SSE2 required by the ABI (that's the first commit). That's kind of a hack, but it is the easiest way to make a target feature required via the target spec. In a follow-up change (rust-lang#135408), we can actually make use of SSE2 for the ABI, but that is running into some infrastructure issues.

r? `@workingjubilee`

try-job: aarch64-apple
try-job: aarch64-gnu
try-job: aarch64-gnu-debug
try-job: test-various
try-job: x86_64-gnu-nopt
try-job: dist-i586-gnu-i586-i686-musl

…kingjubilee

Rollup of 10 pull requests

Successful merges:

 - rust-lang#133312 (triagebot: automatically add more rustdoc related labels)
 - rust-lang#134016 (Stabilize `const_is_char_boundary` and `const_str_split_at`.)
 - rust-lang#136971 (Add a new check-pass UI test for returning `impl Fn(T) -> impl Trait`)
 - rust-lang#136983 (Prepare standard library for Rust 2024 migration)
 - rust-lang#137002 (Fix early lint check desc in query)
 - rust-lang#137006 (borrowck diagnostics cleanup: remove an unused and a barely-used field)
 - rust-lang#137032 (Decode metadata buffer in one go)
 - rust-lang#137035 (Normalize closure instance before eagerly monomorphizing it)
 - rust-lang#137037 (add x86-sse2 (32bit) ABI that requires SSE2 target feature)
 - rust-lang#137038 (llvm: Tolerate captures in tests)

r? `@ghost`
`@rustbot` modify labels: rollup

Rollup merge of rust-lang#137037 - RalfJung:x86-sse2-abi, r=workingjubilee

add x86-sse2 (32bit) ABI that requires SSE2 target feature

This is the first commit of rust-lang#135408:

The primary goal of this is to make SSE2 required for our i686 targets (at least for the ones that use Pentium 4 as their baseline), to ensure they cannot be affected by rust-lang#114479. This has been MCPd in rust-lang/compiler-team#808, and is tracked in rust-lang#133611.

We do this by defining a new ABI that these targets select, and making SSE2 required by the ABI (that's the first commit). That's kind of a hack, but it is the easiest way to make a target feature required via the target spec. In a follow-up change (rust-lang#135408), we can actually make use of SSE2 for the ABI, but that is running into some infrastructure issues.

r? `@workingjubilee`

try-job: aarch64-apple
try-job: aarch64-gnu
try-job: aarch64-gnu-debug
try-job: test-various
try-job: x86_64-gnu-nopt
try-job: dist-i586-gnu-i586-i686-musl

x86: use SSE2 to pass float and SIMD types

This builds on the new X86Sse2 ABI landed in rust-lang#137037 to actually make it a separate ABI from the default x86 ABI, and use SSE2 registers. Specifically, we use it in two ways: to return `f64` values in a register rather than by-ptr, and to pass vectors of size up to 128bit in a register (or, well, whatever LLVM does when passing `<4 x float>` by-val, I don't actually know if this ends up in a register).

Cc `@workingjubilee`
Fixes rust-lang#133611

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try-job: x86_64-msvc-1

x86: use SSE2 to pass float and SIMD types

This builds on the new X86Sse2 ABI landed in rust-lang#137037 to actually make it a separate ABI from the default x86 ABI, and use SSE2 registers. Specifically, we use it in two ways: to return `f64` values in a register rather than by-ptr, and to pass vectors of size up to 128bit in a register (or, well, whatever LLVM does when passing `<4 x float>` by-val, I don't actually know if this ends up in a register).

Cc `@workingjubilee`
Fixes rust-lang#133611

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try-job: dist-i586-gnu-i586-i686-musl
try-job: x86_64-msvc-1

x86: use SSE2 to pass float and SIMD types

This builds on the new X86Sse2 ABI landed in rust-lang#137037 to actually make it a separate ABI from the default x86 ABI, and use SSE2 registers. Specifically, we use it in two ways: to return `f64` values in a register rather than by-ptr, and to pass vectors of size up to 128bit in a register (or, well, whatever LLVM does when passing `<4 x float>` by-val, I don't actually know if this ends up in a register).

Cc `@workingjubilee`
Fixes rust-lang#133611

try-job: aarch64-apple
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try-job: dist-i586-gnu-i586-i686-musl
try-job: x86_64-msvc-1

x86: use SSE2 to pass float and SIMD types

This builds on the new X86Sse2 ABI landed in rust-lang/rust#137037 to actually make it a separate ABI from the default x86 ABI, and use SSE2 registers. Specifically, we use it in two ways: to return `f64` values in a register rather than by-ptr, and to pass vectors of size up to 128bit in a register (or, well, whatever LLVM does when passing `<4 x float>` by-val, I don't actually know if this ends up in a register).

Cc `@workingjubilee`
Fixes #133611

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Upstream changes relative to 1.85.1:

Version 1.86.0 (2025-04-03)
==========================

Language
--------
- [Stabilize upcasting trait objects to supertraits.]
  (rust-lang/rust#134367)
- [Allow safe functions to be marked with the `#[target_feature]` attribute.]
  (rust-lang/rust#134090)
- [The `missing_abi` lint now warns-by-default.]
  (rust-lang/rust#132397)
- Rust now lints about double negations, to catch cases that might
  have intended to be a prefix decrement operator (`--x`) as written
  in other languages. This was previously a clippy lint,
  `clippy::double_neg`, and is [now available directly in Rust as
  `double_negations`.]
  (rust-lang/rust#126604)
- [More pointers are now detected as definitely not-null based on
  their alignment in const eval.]
  (rust-lang/rust#133700)
- [Empty `repr()` attribute applied to invalid items are now
  correctly rejected.]
  (rust-lang/rust#133925)
- [Inner attributes `#![test]` and `#![rustfmt::skip]` are no longer
  accepted in more places than intended.]
  (rust-lang/rust#134276)

Compiler
--------
- [Debug-assert that raw pointers are non-null on access.]
  (rust-lang/rust#134424)
- [Change `-O` to mean `-C opt-level=3` instead of `-C opt-level=2`
  to match Cargo's defaults.]
  (rust-lang/rust#135439)
- [Fix emission of `overflowing_literals` under certain macro environments.]
  (rust-lang/rust#136393)

Platform Support
----------------
- [Replace `i686-unknown-redox` target with `i586-unknown-redox`.]
  (rust-lang/rust#136698)
- [Increase baseline CPU of `i686-unknown-hurd-gnu` to Pentium 4.]
  (rust-lang/rust#136700)
- New tier 3 targets:
  - [`{aarch64-unknown,x86_64-pc}-nto-qnx710_iosock`]
    (rust-lang/rust#133631).
    For supporting Neutrino QNX 7.1 with `io-socket` network stack.
  - [`{aarch64-unknown,x86_64-pc}-nto-qnx800`]
    (rust-lang/rust#133631).
    For supporting Neutrino QNX 8.0 (`no_std`-only).
  - [`{x86_64,i686}-win7-windows-gnu`]
    (rust-lang/rust#134609).
    Intended for backwards compatibility with Windows 7.
    `{x86_64,i686}-win7-windows-msvc` are the Windows MSVC counterparts
    that already exist as Tier 3 targets.
  - [`amdgcn-amd-amdhsa`](rust-lang/rust#134740).
  - [`x86_64-pc-cygwin`](rust-lang/rust#134999).
  - [`{mips,mipsel}-mti-none-elf`]
    (rust-lang/rust#135074).
    Initial bare-metal support.
  - [`m68k-unknown-none-elf`](rust-lang/rust#135085).
  - [`armv7a-nuttx-{eabi,eabihf}`, `aarch64-unknown-nuttx`, and
    `thumbv7a-nuttx-{eabi,eabihf}`]
    (rust-lang/rust#135757).

Refer to Rust's [platform support page][platform-support-doc]
for more information on Rust's tiered platform support.

Libraries
---------
- The type of `FromBytesWithNulError` in `CStr::from_bytes_with_nul(bytes:
  &[u8]) -> Result<&Self, FromBytesWithNulError>` was [changed from
  an opaque struct to an enum]
  (rust-lang/rust#134143), allowing users
  to examine why the conversion failed.
- [Remove `RustcDecodable` and `RustcEncodable`.]
  (rust-lang/rust#134272)
- [Deprecate libtest's `--logfile` option.]
  (rust-lang/rust#134283)
- [On recent versions of Windows, `std::fs::remove_file` will now
  remove read-only files.]
  (rust-lang/rust#134679)

Stabilized APIs
---------------

- [`{float}::next_down`]
  (https://doc.rust-lang.org/stable/std/primitive.f64.html#method.next_down)
- [`{float}::next_up`]
  (https://doc.rust-lang.org/stable/std/primitive.f64.html#method.next_up)
- [`<[_]>::get_disjoint_mut`]
  (https://doc.rust-lang.org/stable/std/primitive.slice.html#method.get_disjoint_mut)
- [`<[_]>::get_disjoint_unchecked_mut`]
  (https://doc.rust-lang.org/stable/std/primitive.slice.html#method.get_disjoint_unchecked_mut)
- [`slice::GetDisjointMutError`]
  (https://doc.rust-lang.org/stable/std/slice/enum.GetDisjointMutError.html)
- [`HashMap::get_disjoint_mut`]
  (https://doc.rust-lang.org/std/collections/hash_map/struct.HashMap.html#method.get_disjoint_mut)
- [`HashMap::get_disjoint_unchecked_mut`]
  (https://doc.rust-lang.org/std/collections/hash_map/struct.HashMap.html#method.get_disjoint_unchecked_mut)
- [`NonZero::count_ones`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZero.html#method.count_ones)
- [`Vec::pop_if`]
  (https://doc.rust-lang.org/std/vec/struct.Vec.html#method.pop_if)
- [`sync::Once::wait`]
  (https://doc.rust-lang.org/stable/std/sync/struct.Once.html#method.wait)
- [`sync::Once::wait_force`]
  (https://doc.rust-lang.org/stable/std/sync/struct.Once.html#method.wait_force)
- [`sync::OnceLock::wait`]
  (https://doc.rust-lang.org/stable/std/sync/struct.OnceLock.html#method.wait)

These APIs are now stable in const contexts:

- [`hint::black_box`]
  (https://doc.rust-lang.org/stable/std/hint/fn.black_box.html)
- [`io::Cursor::get_mut`]
  (https://doc.rust-lang.org/stable/std/io/struct.Cursor.html#method.get_mut)
- [`io::Cursor::set_position`]
  (https://doc.rust-lang.org/stable/std/io/struct.Cursor.html#method.set_position)
- [`str::is_char_boundary`]
  (https://doc.rust-lang.org/stable/std/primitive.str.html#method.is_char_boundary)
- [`str::split_at`]
  (https://doc.rust-lang.org/stable/std/primitive.str.html#method.split_at)
- [`str::split_at_checked`]
  (https://doc.rust-lang.org/stable/std/primitive.str.html#method.split_at_checked)
- [`str::split_at_mut`]
  (https://doc.rust-lang.org/stable/std/primitive.str.html#method.split_at_mut)
- [`str::split_at_mut_checked`]
  (https://doc.rust-lang.org/stable/std/primitive.str.html#method.split_at_mut_checked)

Cargo
-----
- [When merging, replace rather than combine configuration keys
  that refer to a program path and its arguments.]
  (rust-lang/cargo#15066)
- [Error if both `--package` and `--workspace` are passed but the
  requested package is missing.]
  (rust-lang/cargo#15071) This was previously
  silently ignored, which was considered a bug since missing packages
  should be reported.
- [Deprecate the token argument in `cargo login` to avoid shell history leaks.]
  (rust-lang/cargo#15057)
- [Simplify the implementation of `SourceID` comparisons.]
  (rust-lang/cargo#14980) This may
  potentially change behavior if the canonicalized URL compares
  differently in alternative registries.

Rustdoc
-----
- [Add a sans-serif font setting.]
  (rust-lang/rust#133636)

Compatibility Notes
-------------------
- [The `wasm_c_abi` future compatibility warning is now a hard error.]
  (rust-lang/rust#133951)
  Users of `wasm-bindgen` should upgrade to at least version 0.2.89,
  otherwise compilation will fail.
- [Remove long-deprecated no-op attributes `#![no_start]` and `#![crate_id]`.]
  (rust-lang/rust#134300)
- [The future incompatibility lint `cenum_impl_drop_cast` has been
  made into a hard error.]
  (rust-lang/rust#135964) This means it is
  now an error to cast a field-less enum to an integer if the enum
  implements `Drop`.
- [SSE2 is now required for "i686" 32-bit x86 hard-float targets;
  disabling it causes a warning that will become a hard error
  eventually.]
  (rust-lang/rust#137037) To compile for
  pre-SSE2 32-bit x86, use a "i586" target instead.

Internal Changes
----------------

These changes do not affect any public interfaces of Rust, but they represent
significant improvements to the performance or internals of rustc and related
tools.

- [Build the rustc on AArch64 Linux with ThinLTO + PGO.]
  (rust-lang/rust#133807)
  The ARM 64-bit compiler (AArch64) on Linux is now optimized with
  ThinLTO and PGO, similar to the optimizations we have already
  performed for the x86-64 compiler on Linux. This should make it
  up to 30% faster.