Rollup merge of #133598 - ChayimFriedman2:get-many-mut-detailed-err, r=scottmcm
Change `GetManyMutError` to match T-libs-api decision
That is, differentiate between out-of-bounds and overlapping indices, and remove the generic parameter `N`.
I also exported `GetManyMutError` from `alloc` (and `std`), which was apparently forgotten.
Changing the error to carry additional details means LLVM no longer generates separate short-circuiting branches for the checks, instead it generates one branch at the end. I therefore changed the code to use early returns to make LLVM generate jumps. Benchmark results between the approaches are somewhat mixed, but I chose this approach because it is significantly faster with ranges and also faster with `unwrap()`.
Benchmark (`jumps` refer to short-circuiting, `acc` is not short-circuiting):
```rust
use criterion::{black_box, criterion_group, criterion_main, Criterion};
use my_crate::{get_many_check_valid_acc, get_many_check_valid_jumps, GetManyMutError};
mod externs {
#[unsafe(no_mangle)]
fn foo() {}
#[unsafe(no_mangle)]
fn bar() {}
#[unsafe(no_mangle)]
fn baz() {}
}
unsafe extern "C" {
safe fn foo();
safe fn bar();
safe fn baz();
}
fn bench_method(c: &mut Criterion) {
c.bench_function("jumps two usize", |b| {
b.iter(|| get_many_check_valid_jumps(&[black_box(1), black_box(5)], black_box(10)))
});
c.bench_function("jumps two usize unwrap", |b| {
b.iter(|| get_many_check_valid_jumps(&[black_box(1), black_box(5)], black_box(10)).unwrap())
});
c.bench_function("jumps two usize ok", |b| {
b.iter(|| get_many_check_valid_jumps(&[black_box(1), black_box(5)], black_box(10)).ok())
});
c.bench_function("jumps three usize", |b| {
b.iter(|| {
get_many_check_valid_jumps(&[black_box(1), black_box(5), black_box(7)], black_box(10))
})
});
c.bench_function("jumps three usize match", |b| {
b.iter(|| {
match get_many_check_valid_jumps(
&[black_box(1), black_box(5), black_box(7)],
black_box(10),
) {
Err(GetManyMutError::IndexOutOfBounds) => foo(),
Err(GetManyMutError::OverlappingIndices) => bar(),
Ok(()) => baz(),
}
})
});
c.bench_function("jumps two Range", |b| {
b.iter(|| {
get_many_check_valid_jumps(
&[black_box(1)..black_box(5), black_box(7)..black_box(8)],
black_box(10),
)
})
});
c.bench_function("jumps two RangeInclusive", |b| {
b.iter(|| {
get_many_check_valid_jumps(
&[black_box(1)..=black_box(5), black_box(7)..=black_box(8)],
black_box(10),
)
})
});
c.bench_function("acc two usize", |b| {
b.iter(|| get_many_check_valid_acc(&[black_box(1), black_box(5)], black_box(10)))
});
c.bench_function("acc two usize unwrap", |b| {
b.iter(|| get_many_check_valid_acc(&[black_box(1), black_box(5)], black_box(10)).unwrap())
});
c.bench_function("acc two usize ok", |b| {
b.iter(|| get_many_check_valid_acc(&[black_box(1), black_box(5)], black_box(10)).ok())
});
c.bench_function("acc three usize", |b| {
b.iter(|| {
get_many_check_valid_acc(&[black_box(1), black_box(5), black_box(7)], black_box(10))
})
});
c.bench_function("acc three usize match", |b| {
b.iter(|| {
match get_many_check_valid_jumps(
&[black_box(1), black_box(5), black_box(7)],
black_box(10),
) {
Err(GetManyMutError::IndexOutOfBounds) => foo(),
Err(GetManyMutError::OverlappingIndices) => bar(),
Ok(()) => baz(),
}
})
});
c.bench_function("acc two Range", |b| {
b.iter(|| {
get_many_check_valid_acc(
&[black_box(1)..black_box(5), black_box(7)..black_box(8)],
black_box(10),
)
})
});
c.bench_function("acc two RangeInclusive", |b| {
b.iter(|| {
get_many_check_valid_acc(
&[black_box(1)..=black_box(5), black_box(7)..=black_box(8)],
black_box(10),
)
})
});
}
criterion_group!(benches, bench_method);
criterion_main!(benches);
```
Benchmark results:
```none
jumps two usize time: [586.44 ps 590.20 ps 594.50 ps]
jumps two usize unwrap time: [390.44 ps 393.63 ps 397.44 ps]
jumps two usize ok time: [585.52 ps 591.74 ps 599.38 ps]
jumps three usize time: [976.51 ps 983.79 ps 991.51 ps]
jumps three usize match time: [390.82 ps 393.80 ps 397.07 ps]
jumps two Range time: [1.2583 ns 1.2640 ns 1.2695 ns]
jumps two RangeInclusive time: [1.2673 ns 1.2770 ns 1.2877 ns]
acc two usize time: [592.63 ps 596.44 ps 600.52 ps]
acc two usize unwrap time: [582.65 ps 587.07 ps 591.90 ps]
acc two usize ok time: [581.59 ps 587.82 ps 595.71 ps]
acc three usize time: [894.69 ps 901.23 ps 908.24 ps]
acc three usize match time: [392.68 ps 395.73 ps 399.17 ps]
acc two Range time: [1.5531 ns 1.5617 ns 1.5711 ns]
acc two RangeInclusive time: [1.5746 ns 1.5840 ns 1.5939 ns]
```
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