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Author SHA1 Message Date
The 8472
3ed8fccff5 fix OOB access in SIMD impl of str.contains() 2022-11-22 20:59:19 +01:00
Ralf Jung
3a95e12c9b disable strict-provenance-violating doctests in Miri 2022-11-22 11:49:02 +01:00
Manish Goregaokar
1625435fa4
Rollup merge of #102207 - CraftSpider:const-layout, r=scottmcm 
Constify remaining `Layout` methods

Makes the methods on `Layout` that aren't yet unstably const, under the same feature and issue, #67521. Most of them required no changes, only non-trivial change is probably constifying `ValidAlignment` which may affect #102072
 2022-11-22 01:26:07 -05:00
Manish Goregaokar
81ea6105e2
Rollup merge of #95583 - scottmcm:deprecate-ptr-to-from-bits, r=dtolnay 
Deprecate the unstable `ptr_to_from_bits` feature

I propose that we deprecate the (unstable!) `to_bits` and `from_bits` methods on raw pointers.  (With the intent to ~~remove them once `addr` has been around long enough to make the transition easy on people -- maybe another 6 weeks~~ remove them fairly soon after, as the strict and expose versions have been around for a while already.)

The APIs that came from the strict provenance explorations (#95228) are a more holistic version of these, and things like `.expose_addr()` work for the "that cast looks sketchy" case even if the full strict provenance stuff never happens.  (As a bonus, `addr` is even shorter than `to_bits`, though it is only applicable if people can use full strict provenance! `addr` is *not* a direct replacement for `to_bits`.)  So I think it's fine to move away from the `{to|from}_bits` methods, and encourage the others instead.

That also resolves the worry that was brought up (I forget where) that `q.to_bits()` and `(*q).to_bits()` both work if `q` is a pointer-to-floating-point, as they also have a `to_bits` method.

Tracking issue #91126
Code search: https://github.com/search?l=Rust&p=1&q=ptr_to_from_bits&type=Code

For potential pushback, some users in case they want to chime in
- `@RSSchermer` 365bb68541/arwa/src/html/custom_element.rs (L105)
- `@strax` 99616d1dbf/openexr/src/core/alloc.rs (L36)
- `@MiSawa` 577c622358/crates/kernel/src/timer.rs (L50)
 2022-11-22 01:26:05 -05:00
Manish Goregaokar
1dd515f273
Rollup merge of #83608 - Kimundi:index_many, r=Mark-Simulacrum 
Add slice methods for indexing via an array of indices.

Disclaimer: It's been a while since I contributed to the main Rust repo, apologies in advance if this is large enough already that it should've been an RFC.

---

# Update:

- Based on feedback, removed the `&[T]` variant of this API, and removed the requirements for the indices to be sorted.

# Description

This adds the following slice methods to `core`:

```rust
impl<T> [T] {
    pub unsafe fn get_many_unchecked_mut<const N: usize>(&mut self, indices: [usize; N]) -> [&mut T; N];
    pub fn get_many_mut<const N: usize>(&mut self, indices: [usize; N]) -> Option<[&mut T; N]>;
}
```

This allows creating multiple mutable references to disjunct positions in a slice, which previously required writing some awkward code with `split_at_mut()` or `iter_mut()`. For the bound-checked variant, the indices are checked against each other and against the bounds of the slice, which requires `N * (N + 1) / 2` comparison operations.

This has a proof-of-concept standalone implementation here: https://crates.io/crates/index_many

Care has been taken that the implementation passes miri borrow checks, and generates straight-forward assembly (though this was only checked on x86_64).

# Example

```rust
let v = &mut [1, 2, 3, 4];
let [a, b] = v.get_many_mut([0, 2]).unwrap();
std::mem::swap(a, b);
*v += 100;
assert_eq!(v, &[3, 2, 101, 4]);
```

# Codegen Examples

<details>
  <summary>Click to expand!</summary>

Disclaimer: Taken from local tests with the standalone implementation.

## Unchecked Indexing:

```rust
pub unsafe fn example_unchecked(slice: &mut [usize], indices: [usize; 3]) -> [&mut usize; 3] {
    slice.get_many_unchecked_mut(indices)
}
```

```nasm
example_unchecked:
 mov     rcx, qword, ptr, [r9]
 mov     r8, qword, ptr, [r9, +, 8]
 mov     r9, qword, ptr, [r9, +, 16]
 lea     rcx, [rdx, +, 8*rcx]
 lea     r8, [rdx, +, 8*r8]
 lea     rdx, [rdx, +, 8*r9]
 mov     qword, ptr, [rax], rcx
 mov     qword, ptr, [rax, +, 8], r8
 mov     qword, ptr, [rax, +, 16], rdx
 ret
```

## Checked Indexing (Option):

```rust
pub unsafe fn example_option(slice: &mut [usize], indices: [usize; 3]) -> Option<[&mut usize; 3]> {
    slice.get_many_mut(indices)
}
```

```nasm
 mov     r10, qword, ptr, [r9, +, 8]
 mov     rcx, qword, ptr, [r9, +, 16]
 cmp     rcx, r10
 je      .LBB0_7
 mov     r9, qword, ptr, [r9]
 cmp     rcx, r9
 je      .LBB0_7
 cmp     rcx, r8
 jae     .LBB0_7
 cmp     r10, r9
 je      .LBB0_7
 cmp     r9, r8
 jae     .LBB0_7
 cmp     r10, r8
 jae     .LBB0_7
 lea     r8, [rdx, +, 8*r9]
 lea     r9, [rdx, +, 8*r10]
 lea     rcx, [rdx, +, 8*rcx]
 mov     qword, ptr, [rax], r8
 mov     qword, ptr, [rax, +, 8], r9
 mov     qword, ptr, [rax, +, 16], rcx
 ret
.LBB0_7:
 mov     qword, ptr, [rax], 0
 ret
```

## Checked Indexing (Panic):

```rust
pub fn example_panic(slice: &mut [usize], indices: [usize; 3]) -> [&mut usize; 3] {
    let len = slice.len();
    match slice.get_many_mut(indices) {
        Some(s) => s,
        None => {
            let tmp = indices;
            index_many::sorted_bound_check_failed(&tmp, len)
        }
    }
}
```

```nasm
example_panic:
 sub     rsp, 56
 mov     rax, qword, ptr, [r9]
 mov     r10, qword, ptr, [r9, +, 8]
 mov     r9, qword, ptr, [r9, +, 16]
 cmp     r9, r10
 je      .LBB0_6
 cmp     r9, rax
 je      .LBB0_6
 cmp     r9, r8
 jae     .LBB0_6
 cmp     r10, rax
 je      .LBB0_6
 cmp     rax, r8
 jae     .LBB0_6
 cmp     r10, r8
 jae     .LBB0_6
 lea     rax, [rdx, +, 8*rax]
 lea     r8, [rdx, +, 8*r10]
 lea     rdx, [rdx, +, 8*r9]
 mov     qword, ptr, [rcx], rax
 mov     qword, ptr, [rcx, +, 8], r8
 mov     qword, ptr, [rcx, +, 16], rdx
 mov     rax, rcx
 add     rsp, 56
 ret
.LBB0_6:
 mov     qword, ptr, [rsp, +, 32], rax
 mov     qword, ptr, [rsp, +, 40], r10
 mov     qword, ptr, [rsp, +, 48], r9
 lea     rcx, [rsp, +, 32]
 mov     edx, 3
 call    index_many::bound_check_failed
 ud2
```
</details>

# Extensions

There are multiple optional extensions to this.

## Indexing With Ranges

This could easily be expanded to allow indexing with `[I; N]` where `I: SliceIndex<Self>`.  I wanted to keep the initial implementation simple, so I didn't include it yet.

## Panicking Variant

We could also add this method:

```rust
impl<T> [T] {
    fn index_many_mut<const N: usize>(&mut self, indices: [usize; N]) -> [&mut T; N];
}
```

This would work similar to the regular index operator and panic with out-of-bound indices. The advantage would be that we could more easily ensure good codegen with a useful panic message, which is non-trivial with the `Option` variant.

This is implemented in the standalone implementation, and used as basis for the codegen examples here and there.
 2022-11-22 01:26:05 -05:00
David Tolnay
6d943af735
Rustc_deprecated attribute superseded by deprecated 2022-11-21 15:18:36 -08:00
David Tolnay
a9e92be1f9
Bump ptr_to_from_bits deprecation to Rust 1.67 2022-11-21 15:10:59 -08:00
Matthias Krüger
3278dea67a
Rollup merge of #103396 - RalfJung:pinning-closure-captures, r=dtolnay 
Pin::new_unchecked: discuss pinning closure captures

Regardless of how the discussion in https://github.com/rust-lang/rust/pull/102737 turns out, pinning closure captures is super subtle business and probably worth discussing separately.
 2022-11-22 00:01:06 +01:00
Matthias Krüger
369e44943f
Rollup merge of #104420 - TethysSvensson:master, r=JohnTitor 
Fix doc example for `wrapping_abs`

The `max` variable is unused. This change introduces the `min_plus` variable, to make the example similar to the one from `saturating_abs`. An alternative would be to remove the unused variable.
 2022-11-21 14:11:09 +01:00
Matthias Krüger
846574828a
Rollup merge of #104643 - pnkfelix:examples-for-chunks-remainder, r=scottmcm 
add examples to chunks remainder methods.

add examples to chunks remainder methods.

my motivation for adding the examples was to make it very clear that the state of the iterator (in terms of where its cursor lies) has no effect on what remainder returns.

Also fixed some links to rchunk remainder methods.
 2022-11-20 23:50:30 +01:00
Matthias Krüger
b3d491696b
Rollup merge of #104634 - RalfJung:core-arch, r=Mark-Simulacrum 
move core::arch into separate file

This works around https://github.com/rust-lang/rust/issues/104633 which otherwise leads to warnings in miri-test-libstd.
 2022-11-20 23:50:29 +01:00
Matthias Krüger
ff72187b06
Rollup merge of #104632 - RalfJung:core-test-strict-provenance, r=thomcc 
avoid non-strict-provenance casts in libcore tests

r? `@thomcc`
 2022-11-20 23:50:28 +01:00
Rune Tynan
8998711d9b Only one feature gate needed 2022-11-20 17:10:47 -05:00
Rune Tynan
07911879d2 Use ? instead of match 2022-11-20 15:01:22 -05:00
Rune Tynan
a5fecc6905 Fix issue number 2022-11-20 15:01:21 -05:00
Rune Tynan
7972b8aa37 Add derive_const feature 2022-11-20 15:01:21 -05:00
Rune Tynan
6f2dcac78b Update with derive_const 2022-11-20 15:01:21 -05:00
Rune Tynan
414e84a2f7 Add stability for alignment 2022-11-20 15:01:21 -05:00
Rune Tynan
9f4b4e46a3 constify remaining layout methods 
Remove bad impl for Eq

Update Cargo.lock and fix last ValidAlign
 2022-11-20 15:01:21 -05:00
Matthias Krüger
db5f005f35
Rollup merge of #104568 - RalfJung:realloc, r=Amanieu 
clarify that realloc refreshes pointer provenance even when the allocation remains in-place

This [matches what C does](https://en.cppreference.com/w/c/memory/realloc):

> The original pointer ptr is invalidated and any access to it is undefined behavior (even if reallocation was in-place).

Cc `@rust-lang/wg-allocators`
 2022-11-20 18:21:48 +01:00
Felix S. Klock II
98993af828 add examples to chunks remainder methods. Also fixed some links to rchunk remainder methods. 2022-11-20 11:43:23 -05:00
Marvin Löbel
3fe37b8c6e Add get_many_mut methods to slice 2022-11-20 11:19:11 -05:00
Ralf Jung
428ab59fb7 enable fuzzy_provenance_casts in libcore+tests 2022-11-20 16:04:16 +01:00
Tethys Svensson
00bf999fcf Incorporate review feedback 2022-11-20 12:30:14 +01:00
Ralf Jung
e19bc6eb80 move core::arch into separate file 2022-11-20 10:28:14 +01:00
Ralf Jung
2bb28c174b avoid non-strict-provenance casts in libcore tests 2022-11-20 09:58:29 +01:00
Yuki Okushi
785237d392
Rollup merge of #104435 - scottmcm:iter-repeat-n, r=thomcc 
`VecDeque::resize` should re-use the buffer in the passed-in element

Today it always copies it for *every* appended element, but one of those clones is avoidable.

This adds `iter::repeat_n` (https://github.com/rust-lang/rust/issues/104434) as the primitive needed to do this.  If this PR is acceptable, I'll also use this in `Vec` rather than its custom `ExtendElement` type & infrastructure that is harder to share between multiple different containers:

101e1822c3/library/alloc/src/vec/mod.rs (L2479-L2492)
 2022-11-20 13:15:59 +09:00
Yuki Okushi
0858ca97da
Rollup merge of #103901 - H4x5:fmt-arguments-as-str-tracking-issue, r=the8472 
Add tracking issue for `const_arguments_as_str`

Tracking issue: #103900

The original PR didn't create a tracking issue.
 2022-11-20 13:15:58 +09:00
Lukas Markeffsky
c9c017dfb5 update provenance test 
* fix allocation alignment for 16bit platforms
* add edge case where `stride % align != 0` on pointers with provenance
 2022-11-19 16:58:02 +01:00
Lukas
e90d15b247 Update comment on pointer-to-usize transmute 
Co-authored-by: Ralf Jung <post@ralfj.de>
 2022-11-19 16:58:02 +01:00
Lukas Markeffsky
3d7e9c4b7f Revert "don't call align_offset during const eval, ever" 
This reverts commit f3a577bfae376c0222e934911865ed14cddd1539.
 2022-11-19 16:58:02 +01:00
Lukas Markeffsky
9e5d497b67 fix const align_offset implementation 2022-11-19 16:57:58 +01:00
Lukas Markeffsky
8a6053618f docs cleanup 
* Fix doc examples for Platforms with underaligned integer primitives.
* Mutable pointer doc examples use mutable pointers.
* Fill out tracking issue.
* Minor formatting changes.
 2022-11-19 16:47:42 +01:00
Lukas Markeffsky
daccb8c11a always use align_offset in is_aligned_to + add assembly test 2022-11-19 16:47:42 +01:00
Lukas Markeffsky
4696e8906d Schrödinger's pointer 
It's aligned *and* not aligned!
 2022-11-19 16:47:42 +01:00
Lukas Markeffsky
df0bcfe644 address more review comments 
* `cfg` only the body of `align_offset`
* put explicit panics back
* explain why `ptr.align_offset(align) == 0` is slow
 2022-11-19 16:47:42 +01:00
Lukas Markeffsky
093c02ed46 document is_aligned{,_to} 2022-11-19 16:47:42 +01:00
Lukas Markeffsky
a906f6cb69 don't call align_offset during const eval, ever 2022-11-19 16:47:42 +01:00
Lukas Markeffsky
24e88066dc mark align_offset as #[must_use] 2022-11-19 16:47:42 +01:00
Lukas Markeffsky
2ef9a8ae0f add coretests for is_aligned 2022-11-19 16:47:42 +01:00
Lukas Markeffsky
6f6320a0a9 constify pointer::is_aligned{,_to} 2022-11-19 16:47:42 +01:00
Lukas Markeffsky
8cf6b16185 add coretests for const align_offset 2022-11-19 16:47:38 +01:00
Lukas Markeffsky
211743b2c8 make const align_offset useful 2022-11-19 16:36:08 +01:00
Lukas Markeffsky
f13c4f4d6a constify exact_div intrinsic 2022-11-19 16:36:08 +01:00
Dylan DPC
5caac92dc0
Rollup merge of #104528 - WaffleLapkin:lazy_lock_docfix, r=matklad 
Properly link `{Once,Lazy}{Cell,Lock}` in docs

See https://github.com/rust-lang/rust/issues/74465#issuecomment-1317947443
 2022-11-19 11:54:44 +05:30
Scott McMurray
71bb200225 Hide the items while waiting for the ACP 2022-11-18 19:46:18 -08:00
Manish Goregaokar
24ee599195
Rollup merge of #104338 - compiler-errors:pointer-sized, r=eholk 
Enforce that `dyn*` coercions are actually pointer-sized

Implement a perma-unstable, rudimentary `PointerSized` trait to enforce `dyn*` casts are `usize`-sized for now, at least to prevent ICEs and weird codegen issues from cropping up after monomorphization since currently we enforce *nothing*.

This probably can/should be removed in favor of a more sophisticated trait for handling `dyn*` conversions when we decide on one, but I just want to get something up for discussion and experimentation for now.

r? ```@eholk``` cc ```@tmandry``` (though feel free to claim/reassign)

Fixes #102141
Fixes #102173
 2022-11-18 17:48:18 -05:00
Manish Goregaokar
19efa2599c
Rollup merge of #103701 - WaffleLapkin:__points-at-implementation__--this-can-be-simplified, r=scottmcm 
Simplify some pointer method implementations

- Make `pointer::with_metadata_of` const (+simplify implementation) (cc #75091)
- Simplify implementation of various pointer methods

r? ```@scottmcm```

----

`from_raw_parts::<T>(this, metadata(self))` was annoying me for a while and I've finally figured out how it should _actually_ be done.
 2022-11-18 17:48:17 -05:00
Manish Goregaokar
e2301154e3
Rollup merge of #103456 - scottmcm:fix-unchecked-shifts, r=scottmcm 
`unchecked_{shl|shr}` should use `u32` as the RHS

The other shift methods, such as https://doc.rust-lang.org/nightly/std/primitive.u64.html#method.checked_shr and https://doc.rust-lang.org/nightly/std/primitive.i16.html#method.wrapping_shl, use `u32` for the shift amount.  That's consistent with other things, like `count_ones`, which also always use `u32` for a bit count, regardless of the size of the type.

This PR changes `unchecked_shl` and `unchecked_shr` to also use `u32` for the shift amount (rather than Self).

cc #85122, the `unchecked_math` tracking issue
 2022-11-18 17:48:17 -05:00
Manish Goregaokar
6b09d60f82
Rollup merge of #103378 - nagisa:fix-infinite-offset, r=scottmcm 
Fix mod_inv termination for the last iteration

On usize=u64 platforms, the 4th iteration would overflow the `mod_gate` back to 0. Similarly for usize=u32 platforms, the 3rd iteration would overflow much the same way.

I tested various approaches to resolving this, including approaches with `saturating_mul` and `widening_mul` to a double usize. Turns out LLVM likes `mul_with_overflow` the best. In fact now, that LLVM can see the iteration count is limited, it will happily unroll the loop into a nice linear sequence.

You will also notice that the code around the loop got simplified somewhat. Now that LLVM is handling the loop nicely, there isn’t any more reasons to manually unroll the first iteration out of the loop (though looking at the code today I’m not sure all that complexity was necessary in the first place).

Fixes #103361
 2022-11-18 17:48:16 -05:00