Enable Non-determinism of float operations in Miri and change std tests
Links to [#4208](https://github.com/rust-lang/miri/issues/4208) and [#3555](https://github.com/rust-lang/miri/issues/3555) in Miri.
Non-determinism of floating point operations was disabled in rust-lang/rust#137594 because it breaks the tests and doc-tests in core/coretests and std. This PR enables some of them.
This pr includes the following changes:
- Enables the float non-determinism but with a lower relative error of 4ULP instead of 16ULP
- These operations now have a fixed output based on the C23 standard, except the pow operations, this is tracked in [#4286](https://github.com/rust-lang/miri/issues/4286#issue-3010677983)
- Changes tests that made incorrect assumptions about the operations, not to make that assumption anymore (from `assert_eq!` to `assert_approx_eq!`.
- Changed the doctests of the stdlib of these operations to compare against fixed constants instead of `f*::EPSILON`, which now succeed with Miri and `-Zmiri-many-seeds`
- Added a constant `APPROX_DELTA` in `std/tests/floats/f32.rs` which is used for approximation tests, but with a different value when run in Miri. This is to make these tests succeed.
- Added tests in the float tests of Miri to test the C23 behaviour.
Fixes https://github.com/rust-lang/miri/issues/4208
Stabilize `sha512`, `sm3` and `sm4` for x86
This PR stabilizes the feature flag `sha512_sm_x86` (tracking issue rust-lang/rust#126624).
# Public API
The 3 `x86` target features `sha512`, `sm3` and `sm4`, and the associated intrinsics in stdarch.
These target features are very specialized, and are only used to signal the presence of the corresponding CPU instruction. They don't have any nontrivial interaction with the ABI (contrary to something like AVX), and serve the only purpose of enabling 10 stdarch intrinsics, all of which have been implemented and propagated to rustc via a stdarch submodule update.
Also, these were added in LLVM17, and as the minimum LLVM required for rustc is LLVM19, we are safe in that front too!
# Associated PRs
- rust-lang/rust#126704
- rust-lang/stdarch#1592
- rust-lang/stdarch#1790
- rust-lang/rust#140389 (stdarch submodule update)
- rust-lang/stdarch#1796 (stabilizing the runtime detection and intrinsics)
- rust-lang/rust#141964 (stdarch submodule update for the stabilization of the runtime detection and intrinsics)
As all of the required tasks have been done (adding the target features to rustc, implementing their runtime detection in std_detect and implementing the associated intrinsics in core_arch), these target features can be stabilized now.
cc `@rust-lang/lang`
cc `@rust-lang/libs-api` for the intrinsics and runtime detection
I don't think anyone else worked on this feature, so no one else to ping, maybe cc `@Amanieu.` I will send the reference pr soon.
De-duplicate f16 & f128 doctest attributes
Now that rustdoc supports `#[doc(test(attr(...)))]` at every level, thanks to https://github.com/rust-lang/rust/pull/140560, we can de-duplicate the f16 & f128 doctest attributes.
Unfortunately we can de-duplicate the `cfg`s attribute as rustdoc would complain about missing `main`, but it's already much better than before.
Addresses https://github.com/rust-lang/rust/pull/140323/files#r2062702761
r? `@tgross35`
In PR 90877 T-lang decided not to remove `intrinsics::pref_align_of`.
However, the intrinsic and its supporting code
1. is a nightly feature, so can be removed at compiler/libs discretion
2. requires considerable effort in the compiler to support, as it
necessarily complicates every single site reasoning about alignment
3. has been justified based on relevance to codegen, but it is only a
requirement for C++ (not C, not Rust) stack frame layout for AIX,
in ways Rust would not consider even with increased C++ interop
4. is only used by rustc to overalign some globals, not correctness
5. can be adequately replaced by other rules for globals, as it mostly
affects alignments for a few types under 16 bytes of alignment
6. has only one clear benefactor: automating C -> Rust translation
for GNU extensions like `__alignof`
7. such code was likely intended to be `alignof` or `_Alignof`,
because the GNU extension is a "false friend" of the C keyword,
which makes the choice to support such a mapping very questionable
8. makes it easy to do incorrect codegen in the compiler by its mere
presence as usual Rust rules of alignment (e.g. `size == align * N`)
do not hold with preferred alignment
The implementation is clearly damaging the code quality of the compiler.
Thus it is within the compiler team's purview to simply rip it out.
If T-lang wishes to have this intrinsic restored for c2rust's benefit,
it would have to use a radically different implementation that somehow
does not cause internal incorrectness.
Until then, remove the intrinsic and its supporting code, as one tool
and an ill-considered GCC extension cannot justify risking correctness.
Because we touch a fair amount of the compiler to change this at all,
and unfortunately the duplication of AbiAndPrefAlign is deep-rooted,
we keep an "AbiAlign" type which we can wean code off later.
Compute number of digits instead of relying on constant value for u128 display code
As discussed in https://github.com/rust-lang/rust/pull/142098/files#r2132084991, the code should reuse the same logic as the rest of file instead of using a constant value.
r? `@tamird`
UnsafePinned: also include the effects of UnsafeCell
This tackles https://github.com/rust-lang/rust/issues/137750 by including an `UnsafeCell` in `UnsafePinned`, thus imbuing it with all the usual properties of interior mutability (no `noalias` nor `dereferenceable` on shared refs, special treatment by Miri's aliasing model). The soundness issue is not fixed yet because coroutine lowering does not use `UnsafePinned`.
The RFC said that `UnsafePinned` would not permit mutability on shared references, but since then, https://github.com/rust-lang/rust/issues/137750 has demonstrated that this is not tenable. In the face of those examples, I propose that we do the "obvious" thing and permit shared mutable state inside `UnsafePinned`. This seems loosely consistent with the fact that we allow going from `Pin<&mut T>` to `&T` (where the former can be aliased with other pointers that perform mutation, and hence the same goes for the latter) -- but the `as_ref` example shows that we in fact would need to add this `UnsafeCell` even if we didn't have a safe conversion to `&T`, since for the compiler and Miri, `&T` and `Pin<&T>` are basically the same type.
To make this possible, I had to remove the `Copy` and `Clone` impls for `UnsafePinned`.
Tracking issue: https://github.com/rust-lang/rust/issues/125735
Cc ``@rust-lang/lang`` ``@rust-lang/opsem`` ``@Sky9x``
I don't think this needs FCP since the type is still unstable -- we'll finally decide whether we like this approach when `UnsafePinned` is moved towards stabilization (IOW, this PR is reversible). However, I'd still like to make sure that the lang team is okay with the direction I am proposing here.
Improve the documentation of `Display` and `FromStr`, and their interactions
In particular:
- `Display` is not necessarily lossless
- The output of `Display` might not be parseable by `FromStr`, and might
not produce the same value if it is.
- Calling `.parse()` on the output of `Display` is usually a mistake
unless a type's documented output and input formats match.
- The input formats accepted by `FromStr` depend on the type.
This documentation adds no API surface area and makes no guarantees about stability. To the best of my knowledge, everything it says is already established to be true. As such, I don't think it needs an FCP.
- Drop the phrasing "usually a mistake".
- Mention that `Display` may not be lossless.
- Drop a misplaced parenthetical about round-tripping that didn't fit
the paragraph it was in.
In particular:
- `Display` is not necessarily lossless
- The output of `Display` might not be parseable by `FromStr`, and might
not produce the same value if it is.
- Calling `.parse()` on the output of `Display` is usually a mistake
unless a type's documented output and input formats match.
- The input formats accepted by `FromStr` depend on the type.
Remove bootstrap cfgs from library/
These `cfg(bootstrap)` are always false now that rust-lang/rust#119899 has landed, and likewise `cfg(not(bootstrap))` is always true. Therefore, we don't need to wait for the usual stage0 bump to clean these up.
This adds an `iter!` macro that can be used to create movable
generators.
This also adds a yield_expr feature so the `yield` keyword can be used
within iter! macro bodies. This was needed because several unstable
features each need `yield` expressions, so this allows us to stabilize
them separately from any individual feature.
Co-authored-by: Oli Scherer <github35764891676564198441@oli-obk.de>
Co-authored-by: Jieyou Xu <jieyouxu@outlook.com>
Co-authored-by: Travis Cross <tc@traviscross.com>
Rollup of 9 pull requests
Successful merges:
- rust-lang/rust#141554 (Improve documentation for codegen options)
- rust-lang/rust#141817 (rustc_llvm: add Windows system libs only when cross-compiling from Wi…)
- rust-lang/rust#141843 (Add `visit_id` to ast `Visitor`)
- rust-lang/rust#141881 (Subtree update of `rust-analyzer`)
- rust-lang/rust#141898 ([rustdoc-json] Implement PartialOrd and Ord for rustdoc_types::Id)
- rust-lang/rust#141921 (Disable f64 minimum/maximum tests for arm 32)
- rust-lang/rust#141930 (Enable triagebot `[concern]` functionality)
- rust-lang/rust#141936 (Decouple "reporting in deps" from `FutureIncompatibilityReason`)
- rust-lang/rust#141949 (move `test-float-parse` tool into `src/tools` dir)
r? `@ghost`
`@rustbot` modify labels: rollup
Disable f64 minimum/maximum tests for arm 32
This disables the f64 minimum/maximum tests for the arm-unknown-linux-gnueabihf job. The next release will be supporting cross-compiled doctests, and these tests fail on that platform.
It looks like this was just fixed via https://github.com/llvm/llvm-project/pull/142170, but I assume that will not trickle down to our copy of llvm in the next couple of weeks. Assuming that does get fixed when llvm is updated, then these can be removed.
cc https://github.com/rust-lang/rust/issues/141087
This disables the f64 minimum/maximum tests for the
arm-unknown-linux-gnueabihf job. The next release will be supporting
cross-compiled doctests, and these tests fail on that platform.
It looks like this was just fixed via
https://github.com/llvm/llvm-project/pull/142170, but I assume that will
not trickle down to our copy of llvm in the next couple of weeks.
Assuming that does get fixed when llvm is updated, then these can be
removed.
cc https://github.com/rust-lang/rust/issues/141087
