Make some std::intrinsics const fns
#51171
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Eventually I'd like log/sin/cos too const. |
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These are inherently unstable, so there's nothing wrong with making these const except if they were somehow exposed by macros.
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@eddyb I know you dislike these kinds of matches. We could probably do all the ops on u128 and modify the result depending on the type's bitwidth, but that feels fragile
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let extra = 128 - bits;
ctpop(x) = x.count_ones()ctlz(x) = x.leading_zeros() - extracttz(x) = (x << extra).trailing_zeros() - extrabswap(x) = (x << extra).swap_bytes()
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I agree the code can probably be written a bit nicer. Looking into it. Will push as soon as I have the time.
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@leonardo-m I suggest you open a PR for those intrinsics then ;) |
We can't do that because we don't have an soft-float ( |
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@bors r+ |
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📌 Commit 3fefa96 has been approved by |
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🔒 Merge conflict |
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If anything, I'd call these bits, not bytes.
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Ok. I agree. Matches better with the field same in Scalar as well. Pushed a rename.
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Fixed the merge conflict by rebasing. |
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@bors r+ |
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Make some std::intrinsics `const fn`s Making some rustc intrinsics (`ctpop`, `cttz`, `ctlz` and `bswap`) `const fn`s. This is a pre-step to being able to make `swap_bytes`, `to_be` and `from_be` constant functions. That in itself could be ergonomic and useful. But even better is that it would allow `Ipv4Addr::new` etc becoming `const fn`s as well. Which might be really useful since I find it quite common to want to define them as constants. r? @oli-obk
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☀️ Test successful - status-appveyor, status-travis |
const fn integer operations A follow up to rust-lang#51171 Fixes rust-lang#51267 Makes a lot of the integer methods (`swap_bytes`, `count_ones` etc) `const fn`s. See rust-lang#51267 for a discussion about why this is wanted and the solution used.
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Making some rustc intrinsics (
ctpop,cttz,ctlzandbswap)const fns.This is a pre-step to being able to make
swap_bytes,to_beandfrom_beconstant functions. That in itself could be ergonomic and useful. But even better is that it would allowIpv4Addr::newetc becomingconst fns as well. Which might be really useful since I find it quite common to want to define them as constants.r? @oli-obk