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`
Stabilize `tcp_quickack`
to stabilise the quickack part for now, tcp_deferaccept had been added at a later stage.
The related API calls are the following
```rust
// std::os::linux::net
// sealed trait, implemented for std::net::TcpStream
pub trait TcpStreamExt: Sealed{
fn quickack(&self) -> io::Result<bool>;
fn set_quickack(&self, quickack: bool) -> io::Result<()>;
}
```
Closes: https://github.com/rust-lang/rust/issues/96256
Avoid a gratuitous 10s wait in a stress test
`stress_recv_timeout_two_threads`, in the mpmc and mpsc testsuites, is a stress test of the `recv_timeout` function. This test processes and ignores timeouts, and just ensures that every sent value gets received. As such, the exact length of the timeouts is not critical, only that the timeout and sleep durations ensure that at least one timeout occurred.
The current tests have 100 iterations, half of which sleep for 200ms, causing the test to take 10s. This represents around 2/3rds of the *total* runtime of the `library/std` testsuite, and is the only standard library test that takes more than a second.
Reduce this to 50 iterations where half of them sleep for 10ms, causing the test to take 0.25s.
Add a check that at least one timeout occurred.
The `build.rs` entrypoint returns early for some targets, so emscripten
and OpenBSD were not getting check-cfg set. Emit these earlier to avoid
the `unexpected_cfgs` lint.
On the ILP32 `x86_64-unknown-linux-gnux32` target, `usize` is 32 bits so
there is a sub-register alignment warning. Specify the 64-bit `r`
registers, which matches the current default as well as the size of the
other operands in the routines.
There are a few places that violate this lint, which showed up in
rust-lang/rust CI (the relevent module is gated behind
`kernel_user_helpers` which is only set for `armv4t`, `armv5te`, and
`arm-linux-androideabi`; none of these are tested in compiler-builtins
CI). Add new `unsafe { /* ... */ }` blocks where needed to address this.
Some blocks should get a more thorough review of their preconditions, so
their safety comments are left as `FIXME`s.
`stress_recv_timeout_two_threads`, in the mpmc and mpsc testsuites,
is a stress test of the `recv_timeout` function. This test processes and
ignores timeouts, and just ensures that every sent value gets received.
As such, the exact length of the timeouts is not critical, only that
the timeout and sleep durations ensure that at least one timeout
occurred.
The current tests have 100 iterations, half of which sleep for 200ms,
causing the test to take 10s. This represents around 2/3rds of the
*total* runtime of the `library/std` testsuite.
Reduce this to 50 iterations where half of them sleep for 10ms, causing
the test to take 0.25s.
Add a check that at least one timeout occurred.
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.
Many of `std`'s dependency have a dependency on the crates.io
`compiler-builtins` when used with the feature
`rustc-std-workspace-core`. Use a Cargo patch to select the in-tree
version instead.
`compiler-builtins` is also added as a dependency of
`rustc-std-workspace-core` so these crates can remove their crates.io
dependency in the future.
coretests: move float tests from num to floats module and use a more flexible macro to generate them
This makes some progress on https://github.com/rust-lang/rust/issues/141726 by moving the float tests in `num` to `floats` and using a newer, more flexible macro to generate them. We also newly run these tests on f16 and f128 in const, and at runtime in Miri and for hosts where that works well enough.
I didn't yet deduplicate any tests or port the existing `floats::f*` tests to the macro, that can happen in a future PR.
try-job: x86_64-gnu-aux
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`
unsafe keyword docs: emphasize that an unsafe fn in a trait does not get to choose its safety contract
Inspired by discussion in https://github.com/rust-lang/rust/issues/139368.
Cc `@hanna-kruppe`
Reexport types from `c_size_t` in `std`
These are unstably available in `core` and should be in `std` too, but are not currently reexported. Resolve this here.
Tracking issue: https://github.com/rust-lang/rust/issues/88345
Fix AIX build
Fixrust-lang/rust#141543.
`getenv` was moved out of this file to `sys::env::getenv` in rust-lang/rust#140143. Replace its usage with `std::env::var_os`, the publicly exposed version. This matches the other usages of the same function in this file.
Optimize `Seek::stream_len` impl for `File`
It uses the file metadata on Unix with a fallback for files incorrectly reported as zero-sized. It uses `GetFileSizeEx` on Windows.
This reduces the number of syscalls needed for determining the file size of an open file from 3 to 1.
It uses the file metadata on Unix with a fallback for files incorrectly
reported as zero-sized. It uses `GetFileSizeEx` on Windows.
This reduces the number of syscalls needed for determining the file size
of an open file from 3 to 1.
