name old ns/iter new ns/iter diff ns/iter diff % speedup
iter::bench_cycle_take_ref_sum 927,152 927,194 42 0.00% x 1.00
iter::bench_cycle_take_sum 938,129 603,492 -334,637 -35.67% x 1.55
codegen: Fix va_list - aarch64 iOS/Windows
## Summary
Fix code generated for `VaList` on Aarch64 iOS/Windows.
## Details
According to the [Apple - ARM64 Function Calling Conventions]:
> ... the type va_list is an alias for char * rather than for the struct
> type specified in the generic PCS.
The current implementation uses the generic Aarch64 structure for `VaList`
for Aarch64 iOS. Switch to using the `char *` variant of the `VaList`
and use the corresponding `emit_ptr_va_arg` for the `va_arg` intrinsic.
Windows always uses the `char *` variant of the `VaList`. Update the `va_arg`
intrinsic to use `emit_ptr_va_arg`.
[Apple - ARM64 Function Calling Conventions]: https://developer.apple.com/library/archive/documentation/Xcode/Conceptual/iPhoneOSABIReference/Articles/ARM64FunctionCallingConventions.html
According to the Apple developer docs:
> The type va_list is an alias for char * rather than for the struct
> type specified in the generic PCS.
The current implementation uses the generic Aarch64 structure for VaList
for Aarch64 iOS.
Windows always uses the char * variant of the va_list.
This commit replaces many usages of `File::open` and reading or writing
with `fs::read_to_string`, `fs::read` and `fs::write`. This reduces code
complexity, and will improve performance for most reads, since the
functions allocate the buffer to be the size of the file.
I believe that this commit will not impact behavior in any way, so some
matches will check the error kind in case the file was not valid UTF-8.
Some of these cases may not actually care about the error.
Fix a stutter in the docs for slice::exact_chunks
Before this change, the docs for `slice::exact_chunks` reads like this:
> See `chunks` for a variant of this iterator that also returns the remainder as a smaller chunk, and `rchunks_exact` for the same iterator but starting at the end of the slice of the slice.
Notice that stutter at the end? This commit fixes it.
Introduce ptr::hash for references
The RHS is what I used, which wasn't as convenient as `ptr::eq`, so I wondered: should `ptr::hash` exist?
My first Rust PR, so I'm going to need some guidance. :)
Use inner iterator may_have_side_effect for Cloned
Previous implementation wasn't correct, as an inner iterator could have had side effects. Noticed by @bluss in #56534.
drop glue takes in mutable references, it should reflect that in its type
When drop glue begins, it should retag, like all functions taking references do. But to do that, it needs to take the reference at a proper type: `&mut T`, not `*mut T`.
Failing to retag can mean that the memory the reference points to remains frozen, and `EscapeToRaw` on a frozen location is a NOP, meaning later mutations cause a Stacked Borrows violation.
Cc @nikomatsakis @Gankro because Stacked Borrows
Cc @eddyb for the changes to miri argument passing (the intention is to allow passing `*mut [u8]` when `&mut [u8]` is expected and vice versa)
Add libstd Cargo feature "panic_immediate_abort"
It stop asserts and panics from libstd to automatically
include string output and formatting code.
Use case: developing static executables smaller than 50 kilobytes,
where usual formatting code is excessive while keeping debuggability
in debug mode.
May resolve#54981.
Add TryFrom<&[T]> for [T; $N] where T: Copy
`TryFrom<&[T]> for &[T; $N]` (note *reference* to an array) already exists, but not needing to dereference makes type inference easier for example when using `u32::from_be_bytes`.
Also add doc examples doing just that.
It stop asserts and panics from libstd to automatically
include string output and formatting code.
Use case: developing static executables smaller than 50 kilobytes,
where usual formatting code is excessive while keeping debuggability
in debug mode.
May resolve#54981.
libcore: Add VaList and variadic arg handling intrinsics
## Summary
- Add intrinsics for `va_start`, `va_end`, `va_copy`, and `va_arg`.
- Add `core::va_list::VaList` to `libcore`.
Part 1 of (at least) 3 for #44930
Comments and critiques are very much welcomed 😄
Remove unsafe `unsafe` inner function.
Within this `Iterator` implementation, a function `unsafe_get` is
defined which unsafely allows _unchecked_ indexing of any element in a
slice. This should be marked as _unsafe_, but it is not.
To address this issue, I removed that inner function.
atomic::Ordering: Get rid of misleading parts of intro
Remove the parts of atomic::Ordering's intro that wrongly claimed that
SeqCst prevents all reorderings around it.
Closes#55196
This is a (minimal) alternative to #55233.
I also wonder if it would be worth adding at least some warnings that atomics are often a footgun/hard to use correctly, similarly like `mem::transmute` or other functions have.
