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Implement Integer funnel shifts
Tracking issue: rust-lang/rust#145686
ACP: https://github.com/rust-lang/libs-team/issues/642
This implements funnel shifts on primitive integer types. Implements this for cg_llvm, with a fallback impl for everything else
Thanks `@folkertdev` for the fixes and tests
cc `@rust-lang/libs-api`
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- Add a fallback implementation for the intrinsics
- Add LLVM backend support for funnel shifts
Co-Authored-By: folkertdev <folkert@folkertdev.nl>
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"Basic usage" implies there is an example that shows advanced usage,
but these APIs are extra simple.
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Initial implementation of `core_float_math`
Since [1], `compiler-builtins` makes a certain set of math symbols
weakly available on all platforms. This means we can begin exposing some
of the related functions in `core`, so begin this process here.
It is not possible to provide inherent methods in both `core` and `std`
while giving them different stability gates, so standalone functions are
added instead. This provides a way to experiment with the functionality
while unstable; once it is time to stabilize, they can be converted to
inherent.
For `f16` and `f128`, everything is unstable so we can move the inherent
methods.
The following are included to start:
* floor
* ceil
* round
* round_ties_even
* trunc
* fract
* mul_add
* div_euclid
* rem_euclid
* powi
* sqrt
* abs_sub
* cbrt
These mirror the set of functions that we have in `compiler-builtins`
since [1], with the exception of `powi` that has been there longer.
Details for each of the changes is in the commit messages.
Tracking issue: https://github.com/rust-lang/rust/issues/137578
[1]: https://github.com/rust-lang/compiler-builtins/pull/763
try-job: aarch64-gnu
tru-job: armhf-gnu
try-job: i686-msvc-1
try-job: test-various
try-job: x86_64-mingw-1
try-job: x86_64-mingw-2
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Since [1], `compiler-builtins` makes a certain set of math symbols
weakly available on all platforms. This means we can begin exposing some
of the related functions in `core`, so begin this process here.
It is not possible to provide inherent methods in both `core` and `std`
while giving them different stability gates, so standalone functions are
added instead. This provides a way to experiment with the functionality
while unstable; once it is time to stabilize, they can be converted to
inherent.
For `f16` and `f128`, everything is unstable so we can move the inherent
methods.
The following are included to start:
* floor
* ceil
* round
* round_ties_even
* trunc
* fract
* mul_add
* div_euclid
* rem_euclid
* powi
* sqrt
* abs_sub
* cbrt
These mirror the set of functions that we have in `compiler-builtins`
since [1].
Tracking issue: https://github.com/rust-lang/rust/issues/137578
[1]: https://github.com/rust-lang/compiler-builtins/pull/763
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Bump boostrap compiler to new beta
try-job: `*msvc*`
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Use `std::mem::{size_of, size_of_val, align_of, align_of_val}` from the
prelude instead of importing or qualifying them.
These functions were added to all preludes in Rust 1.80.
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Stabilize `num_midpoint_signed` feature
This PR proposes that we stabilize the signed variants of [`iN::midpoint`](https://github.com/rust-lang/rust/issues/110840#issue-1684506201), the operation is equivalent to doing `(a + b) / 2` in a sufficiently large number.
The stabilized API surface would be:
```rust
/// Calculates the middle point of `self` and `rhs`.
///
/// `midpoint(a, b)` is `(a + b) / 2` as if it were performed in a
/// sufficiently-large signed integer type. This implies that the result is
/// always rounded towards zero and that no overflow will ever occur.
impl i{8,16,32,64,128,size} {
pub const fn midpoint(self, rhs: Self) -> Self;
}
```
T-libs-api previously stabilized the unsigned (and float) variants in #131784, the signed variants were left out because of the rounding that should be used in case of negative midpoint.
This stabilization proposal proposes that we round towards zero because:
- it makes the obvious `(a + b) / 2` in a sufficiently-large number always true
- using another rounding for the positive result would be inconsistent with the unsigned variants
- it makes `midpoint(-a, -b)` == `-midpoint(a, b)` always true
- it is consistent with `midpoint(a as f64, b as f64) as i64`
- it makes it possible to always suggest `midpoint` as a replacement for `(a + b) / 2` expressions *(which we may want to do as a future work given the 21.2k hits on [GitHub Search](https://github.com/search?q=lang%3Arust+%2F%5C%28%5Ba-zA-Z_%5D*+%5C%2B+%5Ba-zA-Z_%5D*%5C%29+%5C%2F+2%2F&type=code&p=1))*
`@scottmcm` mentioned a drawback in https://github.com/rust-lang/rust/pull/132191#issuecomment-2439891200:
> I'm torn, because rounding towards zero makes it "wider" than other values, which `>> 1` avoids -- `(a + b) >> 1` has the nice behaviour that `midpoint(a, b) + 2 == midpoint(a + 2, b + 2)`.
>
> But I guess overall sticking with `(a + b) / 2` makes sense as well, and I do like the negation property π€·
Which I think is outweigh by the advantages cited above.
Closes #110840
cc `@rust-lang/libs-api`
cc `@scottmcm`
r? `@dtolnay`
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Implement `int_from_ascii` (#134821)
Provides unstable `T::from_ascii()` and `T::from_ascii_radix()` for integer types `T`, as drafted in tracking issue #134821.
To deduplicate documentation without additional macros, implementations of `isize` and `usize` no longer delegate to equivalent integer types. After #132870 they are inlined anyway.
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This greatly reduces the number of places that actually use the `rustc_layout_scalar_valid_range_*` attributes down to just 3:
```
library/core\src\ptr\non_null.rs
68:#[rustc_layout_scalar_valid_range_start(1)]
library/core\src\num\niche_types.rs
19: #[rustc_layout_scalar_valid_range_start($low)]
20: #[rustc_layout_scalar_valid_range_end($high)]
```
Everything else -- PAL Nanoseconds, alloc's `Cap`, niched FDs, etc -- all just wrap those `niche_types` types.
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Provides unstable `T::from_ascii()` and `T::from_ascii_radix()` for integer
types `T`, as drafted in tracking issue #134821.
To deduplicate documentation without additional macros, implementations of
`isize` and `usize` no longer delegate to equivalent integer types.
After #132870 they are inlined anyway.
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Including implementing it for `u128`, so it can be defined in `uint_impl!`.
This way it works for all backends, including CTFE.
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Stabilize unsigned and float variants of `num_midpoint` feature
This PR proposes that we stabilize the unsigned variants of the [`num_midpoint`](https://github.com/rust-lang/rust/issues/110840#issue-1684506201) feature as well as the floats variants, since they are not subject to any unresolved questions, which is equivalent to doing `(a + b) / 2` (and `(a + b) >> 1`) in a sufficiently large number.
The stabilized API surface would be:
```rust
/// Calculates the middle point of `self` and `rhs`.
///
/// `midpoint(a, b)` is `(a + b) / 2` as if it were performed in a sufficiently-large unsigned integral type.
/// This implies that the result is always rounded towards negative infinity and that no overflow will ever occur.
impl u{8,16,32,64,128,size} {
pub const fn midpoint(self, rhs: Self) -> Self;
}
impl NonZeroU{8,16,32,64,size} {
pub const fn midpoint(self, rhs: Self) -> Self;
}
impl f{32,64} {
pub const fn midpoint(self, rhs: Self) -> Self;
}
```
The signed variants `u{8,16,32,64,128,size}` would remain gated, until a decision is made about the rounding mode, in other words that the [unresolved questions](https://github.com/rust-lang/rust/issues/110840#issue-1684506201) are resolved.
cc `@rust-lang/libs-api`
cc `@scottmcm`
r? libs-api
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Rollup of 7 pull requests
Successful merges:
- #132702 (CFI: Append debug location to CFI blocks)
- #132851 (Update the doc comment of `ASCII_CASE_MASK`)
- #132948 (stabilize const_unicode_case_lookup)
- #132950 (Use GNU ld on m68k-unknown-linux-gnu)
- #132962 (triagebot: add codegen reviewers)
- #132966 (stabilize const_option_ext)
- #132970 (Add tracking issue number to unsigned_nonzero_div_ceil feature)
r? `@ghost`
`@rustbot` modify labels: rollup
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`#[inline]` integer parsing functions
This improves the performance of `str::parse` into integers.
Before:
```
compare fastest β slowest β median β mean β samples β iters
β°β std β β β β β
ββ 328920585 10.23 ns β 24.8 ns β 10.34 ns β 10.48 ns β 100 β 25600
ββ 3255 8.551 ns β 8.59 ns β 8.551 ns β 8.56 ns β 100 β 25600
β°β 5 7.847 ns β 7.887 ns β 7.847 ns β 7.853 ns β 100 β 25600
```
After:
```
compare fastest β slowest β median β mean β samples β iters
β°β std β β β β β
ββ 328920585 8.316 ns β 23.7 ns β 8.355 ns β 8.491 ns β 100 β 25600
ββ 3255 4.566 ns β 4.588 ns β 4.586 ns β 4.576 ns β 100 β 51200
β°β 5 2.877 ns β 3.697 ns β 2.896 ns β 2.945 ns β 100 β 102400
```
Benchmark:
```rust
fn std(input: &str) -> Result<u64, ParseIntError> {
input.parse()
}
```
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This improves the performance of `str::parse` into integers.
Before:
```
compare fastest β slowest β median β mean β samples β iters
β°β std β β β β β
ββ 328920585 10.23 ns β 24.8 ns β 10.34 ns β 10.48 ns β 100 β 25600
ββ 3255 8.551 ns β 8.59 ns β 8.551 ns β 8.56 ns β 100 β 25600
β°β 5 7.847 ns β 7.887 ns β 7.847 ns β 7.853 ns β 100 β 25600
```
After:
```
compare fastest β slowest β median β mean β samples β iters
β°β std β β β β β
ββ 328920585 8.316 ns β 23.7 ns β 8.355 ns β 8.491 ns β 100 β 25600
ββ 3255 4.566 ns β 4.588 ns β 4.586 ns β 4.576 ns β 100 β 51200
β°β 5 2.877 ns β 3.697 ns β 2.896 ns β 2.945 ns β 100 β 102400
```
Benchmark:
```rust
fn std(input: &str) -> Result<u64, ParseIntError> {
input.parse()
}
```
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also move internal const_panic helpers to a better location
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add const_panic macro to make it easier to fall back to non-formatting panic in const
Suggested by `@tgross35`
r? `@tgross35`
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in const
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As LLVM seems to be outperformed by the complexity of signed 128-bits
number compared to our Hacker's Delight implementation.[^1]
It doesn't seems like it's an improvement for the other sizes[^2], so we
let them with the wide implementation.
[^1]: https://rust.godbolt.org/z/ravE75EYj
[^2]: https://rust.godbolt.org/z/fzr171zKh
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Instead of towards negative infinity as is currently the case.
This done so that the obvious expectations of
`midpoint(a, b) == midpoint(b, a)` and
`midpoint(-a, -b) == -midpoint(a, b)` are true, which makes the even
more obvious implementation `(a + b) / 2` true.
https://github.com/rust-lang/rust/issues/110840#issuecomment-2336753931
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Fundamentally, we have *three* disjoint categories of functions:
1. const-stable functions
2. private/unstable functions that are meant to be callable from const-stable functions
3. functions that can make use of unstable const features
This PR implements the following system:
- `#[rustc_const_stable]` puts functions in the first category. It may only be applied to `#[stable]` functions.
- `#[rustc_const_unstable]` by default puts functions in the third category. The new attribute `#[rustc_const_stable_indirect]` can be added to such a function to move it into the second category.
- `const fn` without a const stability marker are in the second category if they are still unstable. They automatically inherit the feature gate for regular calls, it can now also be used for const-calls.
Also, several holes in recursive const stability checking are being closed.
There's still one potential hole that is hard to avoid, which is when MIR
building automatically inserts calls to a particular function in stable
functions -- which happens in the panic machinery. Those need to *not* be
`rustc_const_unstable` (or manually get a `rustc_const_stable_indirect`) to be
sure they follow recursive const stability. But that's a fairly rare and special
case so IMO it's fine.
The net effect of this is that a `#[unstable]` or unmarked function can be
constified simply by marking it as `const fn`, and it will then be
const-callable from stable `const fn` and subject to recursive const stability
requirements. If it is publicly reachable (which implies it cannot be unmarked),
it will be const-unstable under the same feature gate. Only if the function ever
becomes `#[stable]` does it need a `#[rustc_const_unstable]` or
`#[rustc_const_stable]` marker to decide if this should also imply
const-stability.
Adding `#[rustc_const_unstable]` is only needed for (a) functions that need to
use unstable const lang features (including intrinsics), or (b) `#[stable]`
functions that are not yet intended to be const-stable. Adding
`#[rustc_const_stable]` is only needed for functions that are actually meant to
be directly callable from stable const code. `#[rustc_const_stable_indirect]` is
used to mark intrinsics as const-callable and for `#[rustc_const_unstable]`
functions that are actually called from other, exposed-on-stable `const fn`. No
other attributes are required.
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Mark `u8::make_ascii_uppercase` and `u8::make_ascii_lowercase` as const.
Relevant tracking issue: #130698
This PR extends #130697 by also marking the `make_ascii_uppercase` and `make_ascii_lowercase` methods in `u8` as const.
The `const_char_make_ascii` feature gate is additionally renamed to `const_make_ascii`.
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Rename 'const_char_make_ascii' feature gate to 'const_make_ascii';
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Improve documentation for <integer>::from_str_radix
Two improvements to the documentation:
- Document `-` as a valid character for signed integer destinations
- Make the documentation even more clear that extra whitespace and non-digit characters is invalid. Many other languages, e.g. c++, are very permissive in string to integer routines and simply try to consume as much as they can, ignoring the rest. This is trying to make the transition for developers who are used to the conversion semantics in these languages a bit easier.
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Two improvements to the documentation:
- Document `-` as a valid character for signed integer destinations
- Make the documentation even more clear that extra whitespace and non-digit characters is invalid. Many other
languages, e.g. c++, are very permissive in string to integer routines and simply try to consume as much as they can,
ignoring the rest. This is trying to make the transition for developers who are used to the conversion semantics in
these languages a bit easier.
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