Stabilize the avx512 target features
This PR stabilizes the AVX512 target features - see [this comment](https://github.com/rust-lang/rust/issues/111137#issuecomment-2745821279).
Tracking Issue - #44839
The target feature UI tests have been changed to `x87` (chosen because this is very unlikely to stablize ever, please comment if some other feature will be better)
related: #111137
[win][arm64] Remove 'Arm64 Hazard' undocumented MSVC option and instead disable problematic test
PR #140758 added the undocumented `/arm64hazardfree` MSVC linker flag to work around a test failure where LLVM generated code that would trip a hazard in an outdated ARM processor.
Adding this flag caused issues with LLD, as it doesn't recognize it.
Rethinking the issue, using the undocumented flag seems like the incorrect solution: there's no guarantee that the flag won't be removed in the future, or change its meaning.
Instead, I've disabled the problematic test for Arm64 Windows and have filed a bug with the MSVC team to have the check removed: <https://developercommunity.microsoft.com/t/Remove-checking-for-and-fixing-Cortex-A/10905134>
This PR supersedes #140977
r? ```@jieyouxu```
Unfortunately, multiple people are reporting linker warnings related to
`__rust_no_alloc_shim_is_unstable` after this change. The solution isn't
quite clear yet, let's revert to green for now, and try a reland with a
determined solution for `__rust_no_alloc_shim_is_unstable`.
This reverts commit c8b7f32434, reversing
changes made to 667247db71.
Stage0 bootstrap update
This PR [follows the release process](https://forge.rust-lang.org/release/process.html#master-bootstrap-update-tuesday) to update the stage0 compiler.
The only thing of note is 58651d1b31, which was flagged by clippy as a correctness fix. I think allowing that lint in our case makes sense, but it's worth to have a second pair of eyes on it.
r? `@Mark-Simulacrum`
Partially stabilize LoongArch target features
Stabilization PR for the LoongArch target features. This PR stabilizes some of the target features tracked by #44839.
Specifically, this PR stabilizes the following target features:
* f
* d
* frecipe
* lasx
* lbt
* lsx
* lvz
Docs PR: https://github.com/rust-lang/reference/pull/1707
r? `@Amanieu`
Enable non-leaf Frame Pointers for Arm64 Windows
Microsoft recommends enabling frame pointers for Arm64 Windows as it enables fast stack walking, from <https://learn.microsoft.com/en-us/cpp/build/arm64-windows-abi-conventions?view=msvc-170#integer-registers>:
> The frame pointer (x29) is required for compatibility with fast stack walking used by ETW and other services. It must point to the previous {x29, x30} pair on the stack.
I'm setting this to "non-leaf" as leaf functions shouldn't be spilling registers and so won't touch the frame pointer.
Fix linking statics on Arm64EC
Arm64EC builds recently started to fail due to the linker not finding a symbol:
```
symbols.o : error LNK2001: unresolved external symbol #_ZN3std9panicking11EMPTY_PANIC17hc8d2b903527827f1E (EC Symbol)
C:\Code\hello-world\target\arm64ec-pc-windows-msvc\debug\deps\hello_world.exe : fatal error LNK1120: 1 unresolved externals
```
It turns out that `EMPTY_PANIC` is a new static variable that was being exported then imported from the standard library, but when exporting LLVM didn't prepend the name with `#` (as only functions are prefixed with this character), whereas Rust was prefixing with `#` when attempting to import it.
The fix is to have Rust not prefix statics with `#` when importing.
Adding tests discovered another issue: we need to correctly mark static exported from dylibs with `DATA`, otherwise MSVC's linker assumes they are functions and complains that there is no exit thunk for them.
CI found another bug: we only apply `DllImport` to non-local statics that aren't foreign items (i.e., in an `extern` block), that is we want to use `DllImport` for statics coming from other Rust crates. However, `__rust_no_alloc_shim_is_unstable` is a static generated by the Rust compiler if required, but downstream crates consider it a foreign item since it is declared in an `extern "Rust"` block, thus they do not apply `DllImport` to it and so fails to link if it is exported by the previous crate as `DATA`. The fix is to apply `DllImport` to foreign items that are marked with the `rustc_std_internal_symbol` attribute (i.e., we assume they aren't actually foreign and will be in some Rust crate).
Fixes#138541
---
try-job: dist-aarch64-msvc
try-job: dist-x86_64-msvc
try-job: x86_64-msvc-1
try-job: x86_64-msvc-2
[win][arm64] Disable MSVC Linker 'Arm Hazard' warning
While trying to get the aarch64-msvc build working correctly (#140136), I observed the following test failure:
From <https://github.com/rust-lang/rust/pull/140136#issuecomment-2848179657>
```
= note: main.main.d17f5fbe6225cf88-cgu.0.rcgu.o : fatal error LNK1322: cannot avoid potential ARM hazard (Cortex-A53 MPCore processor bug #843419) in section 0x57; please consider using compiler option /Gy if it was not used
```
This is warning of a code sequence that triggers a bug in Cortex-A53 processors: <https://developer.arm.com/documentation/epm048406/latest>
However, since Windows 10 isn't supported on the Cortex-A53, this warning is not required, so it can be suppressed using the undocumented `/arm64hazardfree` flag.
Add the AVX10 target features
Parent #138843
Adds the `avx10_target_feature` feature gate, and `avx10.1` and `avx10.2` target features.
It is confirmed that Intel is dropping AVX10/256 (see [this comment](https://github.com/rust-lang/rust/issues/111137#issuecomment-2795442288)), so this should be safe to implement now.
The LLVM fix for llvm/llvm-project#135394 was merged, and has been backported to LLVM20, and the patch has also been propagated to rustc in #140502
`@rustbot` label O-x86_64 O-x86_32 A-target-feature A-SIMD
Remove `avx512dq` and `avx512vl` implication for `avx512fp16`
According to Intel, `avx512fp16` requires only `avx512bw`, but LLVM also enables `avx512vl` and `avx512dq` when `avx512fp16` is active. This is relic code, and will be fixed in LLVM soon. We should remove this from Rust too asap, especially before the stabilization of AVX512
Related:
- llvm/llvm-project#136209
- #138940
- rust-lang/stdarch#1781
- #111137
``@rustbot`` label O-x86_64 O-x86_32 A-SIMD A-target-feature T-compiler -T-libs
r? ``@Amanieu``
**Update: the LLVM fix has been merged**
cc ``@rust-lang/wg-llvm`` will it be possible to update the rustc llvm version to something after llvm/llvm-project#137450
rustc_target: RISC-V `Zfinx` is incompatible with `{ILP32,LP64}[FD]` ABIs
Because RISC-V Calling Conventions note that:
> This means code targeting the `Zfinx` extension always uses the ILP32, ILP32E or LP64 integer calling-convention only ABIs as there is no dedicated hardware floating-point register file.
`{ILP32,LP64}[FD]` ABIs with hardware floating-point calling conventions are incompatible with the `Zfinx` extension.
This commit adds `"zfinx"` to the incompatible feature list to those ABIs and tests whether trying to add `"zdinx"` (that is analogous to `"zfinx"` but in double-precision) on a LP64D ABI configuration results in an error (it also tests extension implication; `Zdinx` requires `Zfinx` extension).
Links: RISC-V psABI specification version 1.0
<https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/v1.0/riscv-cc.adoc#named-abis>
<https://github.com/riscv-non-isa/riscv-elf-psabi-doc/releases/tag/v1.0>
Because RISC-V Calling Conventions note that:
> This means code targeting the Zfinx extension always uses the ILP32,
> ILP32E or LP64 integer calling-convention only ABIs as there is no
> dedicated hardware floating-point register file.
{ILP32,LP64}[FD] ABIs with hardware floating-point calling conventions
are incompatible with the "Zfinx" extension.
This commit adds "zfinx" to the incompatible feature list to those ABIs
and tests whether trying to add "zdinx" (that is analogous to "zfinx" but
in double-precision) on a LP64D ABI configuration results in an error
(it also tests extension implication; "Zdinx" requires "Zfinx" extension).
Link: RISC-V psABI specification version 1.0
<https://github.com/riscv-non-isa/riscv-elf-psabi-doc/releases/tag/v1.0>
This commit adds three ratified unprivileged RISC-V extensions related to
BFloat16 (BF16) handling.
Although that they are far from stabilization due to ABI issues, they are
optional extensions of the RVA23U64 profile (application-class processor
profile) and going to be discoverable from the Linux kernel
(as of version 6.15-rc4).
This commit mainly prepares runtime detection of those extensions.
This commit adds a part of RISC-V extensions that are mandatory part of
the RVA23U64 profile (application-class processor profile) and related to
memory/atomic constraints.
The Zic64b extension constrains the cache line to naturally-aligned 64 bytes
that would make certain memory operations (like zeroing the memory using
the Zicboz extension) easier.
The Zicbom and Zicbop extensions enable managing cache block-based
operations (the Zicbop contains hints that will work as a NOP when this
extension is absent and the Zicbom contains control instructions).
Of which, the Zicbom extension is going to be discoverable from the Linux
kernel (as of the version 6.15-rc4) and this commit prepares for
corresponding stdarch changes.
The Zicc* extensions add certain constraints to "the main memory" (usually
true on the user mode application on the application-class processor but
those extensions make sure such constraints exist).
The Za64rs extension (reservation set -- a primitive memory unit of LR/SC
atomic operations -- is naturally aligned and *at most* 64 bytes) is a
superset of the Za128rs extension (*at most* 128 bytes; note that smaller
the reservation set is, more fine grained control over atomics).
This commit handles this as a feature implication.
Make #![feature(let_chains)] bootstrap conditional in compiler/
Let chains have been stabilized recently in #132833, so we can remove the gating from our uses in the compiler (as the compiler uses edition 2024).
rustc_target: Adjust RISC-V feature implication
This commit adjusts feature implication of the RISC-V ISA for better feature detection from the user perspective.
The main rule is:
* If the feature `A` is a functional superset of the feature `B` (`A ⊃ B`),
`A` is to imply `B`, even if this implication is not on the manual.
Such implications (not directly written in the ISA manual) are commented as `A ⊃ B`
which means "`A` is a (functional) superset of `B`".
1. `Zbc` → `Zbkc` (add as a superset)
The `Zbkc` extension is a subset of the `Zbc` extension (`Zbc` minus `clmulr` instruction).
2. `Zkr` → (nothing) (remove dependency to `Zicsr`)
Implication to the `Zicsr` extension is removed because (although nearly harmless), the `Zkr` extension (or the `seed` CSR section) defines its own subset of the `Zicsr` extension (guaranteed to work against the `seed` CSR which needs read/write access).
3. `Zvbb` → `Zvkb` (comment as a superset)
This implication was already there but not denoted as a functional superset. This commit adds the comment.
4. `Zvfh` → `Zvfhmin` (comment as a superset)
This is similar to the case above (`Zvbb` → `Zvkb`).
5. `Zvfh` → `Zve32f` (add implication per the ISA specification)
This dependency is on the ISA manual but was missing (due to the fact that `Zvfh` indirectly implies `Zve32f` on the current implementation through `Zvfh` → `Zvfhmin` which is a functional relation). This commit ensures that this is *also* ISA-compliant in the source code level (there's no functional changes though).
6. `Zvknhb` → `Zvknha` (add as a superset)
The `Zvknhb` extension (SHA-256 / SHA-512) is a functional superset of the `Zvknha` extension (SHA-256 only).
mitigate MSVC alignment issue on x86-32
This implements mitigation for https://github.com/rust-lang/rust/issues/112480 by stopping to emit `align` attributes on loads and function arguments when building for a win32 MSVC target. MSVC is known to not properly align `u64` and similar types, and claiming to LLVM that everything is properly aligned increases the chance that this will cause problems.
Of course, the misalignment is still a bug, but we can't fix that bug, only MSVC can.
Also add an errata note to the platform support page warning users about this known problem.
try-job: `i686-msvc*`
This commit adjusts feature implication of the RISC-V ISA for better
feature detection from the user perspective.
The main rule is:
If the feature A is a functional superset of the feature B (A ⊃ B),
A is to imply B, even if this implication is not on the manual.
Such implications (not directly referred in the ISA manual) are commented
as "A ⊃ B" which means "A is a (functional) superset of B".
1. Zbc → Zbkc (add as a superset)
The Zbkc extension is a subset of the Zbc extension
(Zbc - "clmulr" instruction == Zbkc)
2. Zkr → (nothing) (remove dependency to Zicsr)
Implication to the Zicsr extension is removed because (although nearly
harmless), the Zkr extension (or the "seed" CSR section) defines its own
subset of the Zicsr extension.
3. Zvbb → Zvkb (comment as a superset)
This implication was already there but not denoted as a functional
superset. This commit adds the comment.
4. Zvfh → Zvfhmin (comment as a superset)
This is similar to the case above (Zvbb → Zvkb).
5. Zvfh → Zve32f (add implication per the ISA specification)
This dependency is on the ISA manual but was missing (due to the fact
that Zvfh indirectly implies Zve32f on the current implementation
through Zvfh → Zvfhmin, which is a functional relation).
This commit ensures that this is *also* ISA-compliant in the
source code level (there's no functional changes though).
6. Zvknhb → Zvknha (add as a superset)
The Zvknhb extension (SHA-256 / SHA-512) is a functional superset of
the Zvknha extension (SHA-256 only).
Move `pal::env` to `std::sys::env_consts`
Combine the `std::env::consts` platform implementations as a single file. Use the Unix file as the base, since it has 28 entries, and fold the 8 singleton platforms into it. The Unix file was roughly grouped into Linux, Apple, BSD, and everything else, roughly in alphabetical order. Alphabetically order them to make it easier to maintain and discard the Unix-specific groups to generalize it to all platforms.
I'd prefer to have no fallback implementation, as I consider it a bug; however TEEOS, Trusty, and Xous have no definitions here. Since they otherwise have `pal` abstractions, that indicates that there are several platforms without `pal` abstractions which are also missing here. To support unsupported, create a little macro to handle the fallback case and not introduce ordering between the `cfg`s like `cfg_if!`.
I've named the module `std::sys::env_consts`, because they are used in `std::env::consts` and I intend to use the name `std::sys::env` for the combination of `Args` and `Vars`.
cc `@joboet` `@ChrisDenton`
Tracked in #117276.
On Windows 7 32-bit, the alignment characteristic of the TLS Directory
don't appear to be respected by the PE Loader, leading to crashes. As
a result, let's disable has_thread_local to make sure TLS goes through
the emulation layer.
Rollup of 9 pull requests
Successful merges:
- #135340 (Add `explicit_extern_abis` Feature and Enforce Explicit ABIs)
- #139440 (rustc_target: RISC-V: feature addition batch 2)
- #139667 (cfi: Remove #[no_sanitize(cfi)] for extern weak functions)
- #139828 (Don't require rigid alias's trait to hold)
- #139854 (Improve parse errors for stray lifetimes in type position)
- #139889 (Clean UI tests 3 of n)
- #139894 (Fix `opt-dist` CLI flag and make it work without LLD)
- #139900 (stepping into impls for normalization is unproductive)
- #139915 (replace some #[rustc_intrinsic] usage with use of the libcore declarations)
r? `@ghost`
`@rustbot` modify labels: rollup
The "B" extension is ratified as a combination of three extensions: "Zba",
"Zbb" and "Zbs". To maximize discoverability of the RISC-V target features,
this commit makes use of the "B" extension instead of its three members.
This way, `#[cfg(target_feature = "b")]` can also be used instead of:
`#[cfg(all(target_feature = "zba", target_feature = "zbb", target_feature = "zbs"))]`
This commit adds unprivileged ratified extensions that are either
dicoverable from the `riscv_hwprobe` syscall of the Linux kernel (as of
version 6.14) plus 1 minus 3 extensions.
Plus 1:
* "B"
This is a combination of "Zba", "Zbb" and "Zbs".
Note:
Although not required by the RISC-V specification, it is convenient to
imply "B" from its three members (will be implemented in LLVM 21/22) but
this is not yet implemented in Rust due to current implication handling.
It still implies three members *from* "B".
Minus 2:
* "Zcf" (target_arch = "riscv32" only)
This is the compression instruction subset corresponding "F".
This is implied from RV32 + "C" + "F" but this complex handling is
not yet supported by Rust's feature handling.
* "Zcd"
This is the compression instruction subset corresponding "D".
This is implied from "C" + "D" but this complex handling is
not yet supported by Rust's feature handling.
* "Supm"
Unlike regular RISC-V extensions, "Supm" and "Sspm" extensions do not
provide any specific architectural features / constraints but requires
*some* mechanisms to control pointer masking for the current mode.
For instance, reported existence of the "Supm" extension in Linux means
that `prctl` system call to control pointer masking is available and
there are alternative ways to detect the existence.
Notes:
* Because this commit adds the "Zca" extension (an integer subset of the
"C" extension), the "C" extension is modified to imply "Zca".
It's possible to build no_std programs with this compiler.
> A tier 3 target must have a designated developer or developers (the "target
maintainers") on record to be CCed when issues arise regarding the target. (The
mechanism to track and CC such developers may evolve over time.)
Tim Newsome (@tnewsome-lynx) will be the designated developer for
x86_64-lynx-lynxos178 support.
> Targets must use naming consistent with any existing targets; for instance, a
target for the same CPU or OS as an existing Rust target should use the same
name for that CPU or OS. Targets should normally use the same names and naming
conventions as used elsewhere in the broader ecosystem beyond Rust (such as in
other toolchains), unless they have a very good reason to diverge. Changing the
name of a target can be highly disruptive, especially once the target reaches a
higher tier, so getting the name right is important even for a tier 3 target.
I believe the target is named appropriately.
> Target names should not introduce undue confusion or ambiguity unless
absolutely necessary to maintain ecosystem compatibility. For example, if the
name of the target makes people extremely likely to form incorrect beliefs about
what it targets, the name should be changed or augmented to disambiguate it.
The target name is not confusing.
> If possible, use only letters, numbers, dashes and underscores for the name.
Periods (.) are known to cause issues in Cargo.
Done.
> Tier 3 targets may have unusual requirements to build or use, but must not
create legal issues or impose onerous legal terms for the Rust project or for
Rust developers or users.
> The target must not introduce license incompatibilities.
> Anything added to the Rust repository must be under the standard Rust license
(MIT OR Apache-2.0).
All this new code is licensed under the Apache-2.0 license.
> The target must not cause the Rust tools or libraries built for any other host
(even when supporting cross-compilation to the target) to depend on any new
dependency less permissive than the Rust licensing policy. This applies whether
the dependency is a Rust crate that would require adding new license exceptions
(as specified by the tidy tool in the rust-lang/rust repository), or whether the
dependency is a native library or binary. In other words, the introduction of
the target must not cause a user installing or running a version of Rust or the
Rust tools to be subject to any new license requirements.
Done.
> Compiling, linking, and emitting functional binaries, libraries, or other code
for the target (whether hosted on the target itself or cross-compiling from
another target) must not depend on proprietary (non-FOSS) libraries. Host tools
built for the target itself may depend on the ordinary runtime libraries
supplied by the platform and commonly used by other applications built for the
target, but those libraries must not be required for code generation for the
target; cross-compilation to the target must not require such libraries at all.
For instance, rustc built for the target may depend on a common proprietary C
runtime library or console output library, but must not depend on a proprietary
code generation library or code optimization library. Rust's license permits
such combinations, but the Rust project has no interest in maintaining such
combinations within the scope of Rust itself, even at tier 3.
I think we're in the clear here. We do link against some static libraries that
are proprietary (like libm and libc), but those are not used to generate code.
E.g. the VxWorks target requires `wr-c++` to be installed, which is not
publically available.
> "onerous" here is an intentionally subjective term. At a minimum, "onerous"
legal/licensing terms include but are not limited to: non-disclosure
requirements, non-compete requirements, contributor license agreements (CLAs) or
equivalent, "non-commercial"/"research-only"/etc terms, requirements conditional
on the employer or employment of any particular Rust developers, revocable
terms, any requirements that create liability for the Rust project or its
developers or users, or any requirements that adversely affect the livelihood or
prospects of the Rust project or its developers or users.
Our intention is to allow anyone with access to LynxOS CDK to use Rust for it.
> Neither this policy nor any decisions made regarding targets shall create any
binding agreement or estoppel by any party. If any member of an approving Rust
team serves as one of the maintainers of a target, or has any legal or
employment requirement (explicit or implicit) that might affect their decisions
regarding a target, they must recuse themselves from any approval decisions
regarding the target's tier status, though they may otherwise participate in
discussions.
> This requirement does not prevent part or all of this policy from being cited
in an explicit contract or work agreement (e.g. to implement or maintain support
for a target). This requirement exists to ensure that a developer or team
responsible for reviewing and approving a target does not face any legal threats
or obligations that would prevent them from freely exercising their judgment in
such approval, even if such judgment involves subjective matters or goes beyond
the letter of these requirements.
No problem.
> Tier 3 targets should attempt to implement as much of the standard libraries
as possible and appropriate (core for most targets, alloc for targets that can
support dynamic memory allocation, std for targets with an operating system or
equivalent layer of system-provided functionality), but may leave some code
unimplemented (either unavailable or stubbed out as appropriate), whether
because the target makes it impossible to implement or challenging to implement.
The authors of pull requests are not obligated to avoid calling any portions of
the standard library on the basis of a tier 3 target not implementing those
portions.
With this first PR, only core is supported. I am working on support for the std
library and intend to submit that once all the tests are passing.
> The target must provide documentation for the Rust community explaining how to
build for the target, using cross-compilation if possible. If the target
supports running binaries, or running tests (even if they do not pass), the
documentation must explain how to run such binaries or tests for the target,
using emulation if possible or dedicated hardware if necessary.
This is documented in `src/doc/rustc/src/platform-support/lynxos_178.md`.
> Tier 3 targets must not impose burden on the authors of pull requests, or
other developers in the community, to maintain the target. In particular, do not
post comments (automated or manual) on a PR that derail or suggest a block on
the PR based on a tier 3 target. Do not send automated messages or notifications
(via any medium, including via @) to a PR author or others involved with a PR
regarding a tier 3 target, unless they have opted into such messages.
> Backlinks such as those generated by the issue/PR tracker when linking to an
issue or PR are not considered a violation of this policy, within reason.
However, such messages (even on a separate repository) must not generate
notifications to anyone involved with a PR who has not requested such
notifications.
Understood.
> Patches adding or updating tier 3 targets must not break any existing tier 2
or tier 1 target, and must not knowingly break another tier 3 target without
approval of either the compiler team or the maintainers of the other tier 3
target.
> In particular, this may come up when working on closely related targets, such
as variations of the same architecture with different features. Avoid
introducing unconditional uses of features that another variation of the target
may not have; use conditional compilation or runtime detection, as appropriate,
to let each target run code supported by that target.
As far as I know this change does not affect any other targets.
> Tier 3 targets must be able to produce assembly using at least one of rustc's
supported backends from any host target. (Having support in a fork of the
backend is not sufficient, it must be upstream.)
Many targets produce assembly for x86_64 so that also works for LynxOS-178.
