Add as_rchunks (and friends) to slices
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r? @sfackler (rust_highfive has picked a reviewer for you, use r? to override) |
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Nov 6, 2020
library/core/src/slice/mod.rs
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| /// ``` | ||
| #[unstable(feature = "slice_as_chunks", issue = "74985")] | ||
| #[inline] | ||
| pub unsafe fn as_chunks_mut_unchecked<const N: usize>(&mut self) -> &mut [[T; N]] { |
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It wasn't obvious to me whether this should be as_chunks_mut_unchecked or as_chunks_unchecked_mut. I could see precedent for both.
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It looks like unchecked_mut is more frequently used but mut_unchecked sounds better to me 😆
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It looks like unchecked_mut has more precedent in slice and iterator APIs so maybe we should roll with that.
I'm very sad that we have a nice mix of both unchecked_mut and mut_unchecked 🥲
scottmcm
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Nov 6, 2020
| pub fn chunks4_with_remainder(x: &[u8]) -> (&[[u8; 4]], &[u8]) { | ||
| // CHECK: and i64 %x.1, -4 | ||
| // CHECK: and i64 %x.1, 3 | ||
| // CHECK: lshr exact |
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I wanted to ensure I didn't accidentally introduce extra instructions with the refactor, so codegen test. It did change, but only from lshr/and/and to and/and/lshr exact, which is a thoroughly uninteresting difference.
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r? @KodrAus |
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Thanks @scottmcm! r=me with |
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@bors r=KodrAus |
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📌 Commit 132307c has been approved by |
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Add `as_rchunks` (and friends) to slices `@est31` mentioned (rust-lang#76354 (comment)) that, for completeness, there needed to be an `as_chunks`-like method that chunks from the end (with the remainder at the beginning) like `rchunks` does. So here's a PR for `as_rchunks: &[T] -> (&[T], &[[T; N]])` and `as_rchunks_mut: &mut [T] -> (&mut [T], &mut [[T; N]])`. But as I was doing this and copy-pasting `from_raw_parts` calls, I thought that I should extract that into an unsafe method. It started out a private helper, but it seemed like `as_chunks_unchecked` could be reasonable as a "real" method, so I added docs and made it public. Let me know if you think it doesn't pull its weight.
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@bors r- This failed in #81085 (comment): The job Click to see the possible cause of the failure (guessed by this bot) |
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@bors rollup=never Sigh, codegen tests. |
This fixed things the last time I had a problem like this. And plausibly will here too -- the check it's failing on is for the high bit being set in the length of the slice, which is a check that's only in a debug_assert.
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@bors r=KodrAus |
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📌 Commit 6bcaba9 has been approved by |
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☀️ Test successful - checks-actions |
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@est31 mentioned (#76354 (comment)) that, for completeness, there needed to be an
as_chunks-like method that chunks from the end (with the remainder at the beginning) likerchunksdoes.So here's a PR for
as_rchunks: &[T] -> (&[T], &[[T; N]])andas_rchunks_mut: &mut [T] -> (&mut [T], &mut [[T; N]]).But as I was doing this and copy-pasting
from_raw_partscalls, I thought that I should extract that into an unsafe method. It started out a private helper, but it seemed likeas_chunks_uncheckedcould be reasonable as a "real" method, so I added docs and made it public. Let me know if you think it doesn't pull its weight.