use libm for acosh and asinh by malezjaa · Pull Request #154051 · rust-lang/rust

malezjaa · 2026-03-18T18:09:00Z

Uses libm for acosh and asinh

rustbot · 2026-03-18T18:09:06Z

rustbot has assigned @joboet.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

Why was this reviewer chosen?

The reviewer was selected based on:

Owners of files modified in this PR: @ChrisDenton, libs
@ChrisDenton, libs expanded to 8 candidates
Random selection from Mark-Simulacrum, joboet

reddevilmidzy · 2026-03-20T14:28:04Z

Hello @malezjaa,
Next time you contribute, please check if someone has been assigned to the issue before contributing.

malezjaa · 2026-03-20T15:27:10Z

I'm really sorry about that. I should've checked If anyone was already assigned to this issue. I'll do that from now on.

rustbot · 2026-03-21T09:01:17Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

tgross35 · 2026-03-26T22:54:00Z

Happy to review this or alternatives, unless you have a preference @joboet

r? tgross35

tgross35 · 2026-03-27T08:37:07Z

this fixes acosh and asinh for large float values using the approximation from libm

Can we just call libm via the cmath moule instead, rather than having the same logic here? Like we do for acos and similar.

Can you also clarify what approximations you are referencing? This isn't what is in https://github.com/rust-lang/compiler-builtins/blob/644346f0541f74fc425070f8e0712f2dac898e11/libm/src/math/acosh.rs.

malezjaa · 2026-03-28T17:05:38Z

Oh yeah that makes sense. I'll update the PR title and description to show that we're now using libm for these functions.
For f128 I kept the existing approximation since I couldn't find the f128 version in libm

reddevilmidzy · 2026-03-31T04:44:56Z

@rustbot author

rustbot · 2026-03-31T04:45:01Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

rustbot · 2026-03-31T06:08:40Z

The Miri subtree was changed

cc @rust-lang/miri

…asinh, r=tgross35 use libm for acosh and asinh for f16, f32, and f64 Fixes rust-lang#153878 Uses libm for `acosh` and `asinh` for `f16`, `f32`, and `f64`. I didn't change impl for f128 as i couldn't find existing function for these in libm

Rollup of 5 pull requests Successful merges: - #153286 (various fixes for scalable vectors) - #153592 (Add `min_adt_const_params` gate) - #154051 (use libm for acosh and asinh for f16, f32, and f64) - #154743 (Remove an unused `StableHash` impl.) - #154752 (Add comment to borrow-checker)

matthiaskrgr · 2026-04-03T18:48:48Z

@bors r-
#154757 (comment)

malezjaa · 2026-04-03T19:38:32Z

Should I just increase ASINH_APPROX, ACOSH_APPROX thresholds for x86 or is that not the solution?

tgross35 · 2026-04-03T19:44:18Z

Ah yeah, i586 has all kinds of issues with floating point accuracy. I would do this as:

/// i586 has issues with floating point precision.
const I586: bool = cfg!(target_arch = "x86") && cfg!(not(target_feature = "sse2"));

impl ... {
    const ASINH_APPROX: Self = if i586 { /* relaxed precision */ } else { /* current precision */ };
}

Make the precision larger than what showed up in the tests to leave some flexibility in the future.

malezjaa · 2026-04-03T20:00:34Z

Oh also, is this only for f32 or for other types too?

tgross35 · 2026-04-03T21:27:14Z

Usually that applies to f32 and f64 (not f16/f128 since they don't have the same ABI), but I guess the f64 precision is already relaxed enough.

tgross35 · 2026-04-04T07:47:08Z

@bors try jobs=dist-i586-gnu-i586-i686-musl

use libm for acosh and asinh for f16, f32, and f64 try-job: dist-i586-gnu-i586-i686-musl

rust-bors · 2026-04-04T09:27:23Z

☀️ Try build successful (CI)
Build commit: f11df1d (f11df1dc95569c28b4706806cc08796343c33564, parent: 2972b5e59f1c5529b6ba770437812fd83ab4ebd4)

tgross35 · 2026-04-04T09:49:02Z

@bors r+

rust-bors · 2026-04-04T09:49:06Z

📌 Commit a1feab1 has been approved by tgross35

It is now in the queue for this repository.

…uwer Rollup of 8 pull requests Successful merges: - #149868 (rustc: Stop passing `--allow-undefined` on wasm targets) - #153555 (Clarified docs in std::sync::RwLock + added test to ensure that max reader count is respected) - #152851 (Fix SGX delayed host lookup via ToSocketAddr) - #154051 (use libm for acosh and asinh) - #154581 (More informative `Debug for vec::ExtractIf`) - #154461 (Edit the docs new_in() and with_capacity_in()) - #154526 (Panic/return false on overflow in no_threads read/try_read impl) - #154798 (rustdoc-search: match path components on words)

Rollup merge of #154051 - malezjaa:approximations-acosh-and-asinh, r=tgross35 use libm for acosh and asinh Fixes #153878 Uses libm for `acosh` and `asinh`

malezjaa · 2026-04-04T22:10:46Z

Thank you for your time with this PR :D

tgross35 · 2026-04-04T22:59:27Z

We’re happy to help :) thank you for working on it!

…uwer Rollup of 8 pull requests Successful merges: - rust-lang/rust#149868 (rustc: Stop passing `--allow-undefined` on wasm targets) - rust-lang/rust#153555 (Clarified docs in std::sync::RwLock + added test to ensure that max reader count is respected) - rust-lang/rust#152851 (Fix SGX delayed host lookup via ToSocketAddr) - rust-lang/rust#154051 (use libm for acosh and asinh) - rust-lang/rust#154581 (More informative `Debug for vec::ExtractIf`) - rust-lang/rust#154461 (Edit the docs new_in() and with_capacity_in()) - rust-lang/rust#154526 (Panic/return false on overflow in no_threads read/try_read impl) - rust-lang/rust#154798 (rustdoc-search: match path components on words)

rustbot assigned joboet Mar 18, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Mar 18, 2026

This comment has been minimized.

Sign in to view

malezjaa force-pushed the approximations-acosh-and-asinh branch from 4a67c1e to 90a7256 Compare March 21, 2026 09:01

rustbot assigned tgross35 and unassigned joboet Mar 26, 2026

malezjaa changed the title ~~return approximations for large float values in acosh and asinh~~ use libm for acosh and asinh for f16, f32, and f64 Mar 28, 2026

malezjaa marked this pull request as draft March 28, 2026 16:41

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Mar 28, 2026

malezjaa force-pushed the approximations-acosh-and-asinh branch from 3a210bb to 538e681 Compare March 28, 2026 17:02

malezjaa marked this pull request as ready for review March 28, 2026 17:05

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Mar 28, 2026

This comment has been minimized.

Sign in to view

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Mar 31, 2026

malezjaa force-pushed the approximations-acosh-and-asinh branch from 538e681 to abd315c Compare March 31, 2026 06:08

This comment has been minimized.

Sign in to view

matthiaskrgr mentioned this pull request Apr 3, 2026

Rollup of 5 pull requests #154757

Closed

rust-bors bot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Apr 3, 2026

use libm for acosh and asinh

a1feab1

malezjaa force-pushed the approximations-acosh-and-asinh branch from e83e484 to a1feab1 Compare April 4, 2026 07:30

This comment has been minimized.

Sign in to view

rust-bors bot pushed a commit that referenced this pull request Apr 4, 2026

Auto merge of #154051 - malezjaa:approximations-acosh-and-asinh, r=<try>

f11df1d

use libm for acosh and asinh for f16, f32, and f64 try-job: dist-i586-gnu-i586-i686-musl

malezjaa changed the title ~~use libm for acosh and asinh for f16, f32, and f64~~ use libm for acosh and asinh Apr 4, 2026

rust-bors bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Apr 4, 2026

JonathanBrouwer mentioned this pull request Apr 4, 2026

Rollup of 8 pull requests #154815

Merged

rust-bors bot merged commit 69751ec into rust-lang:main Apr 4, 2026
12 checks passed

rustbot added this to the 1.96.0 milestone Apr 4, 2026

rust-timer added a commit that referenced this pull request Apr 4, 2026

Unrolled build for #154051

94c5e67

Rollup merge of #154051 - malezjaa:approximations-acosh-and-asinh, r=tgross35 use libm for acosh and asinh Fixes #153878 Uses libm for `acosh` and `asinh`

tgross35 mentioned this pull request Apr 5, 2026

Automatic Rustup rust-lang/miri#4941

Merged

Uh oh!

Conversation

malezjaa commented Mar 18, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

rustbot commented Mar 18, 2026

Uh oh!

reddevilmidzy commented Mar 20, 2026

Uh oh!

malezjaa commented Mar 20, 2026

Uh oh!

This comment has been minimized.

rustbot commented Mar 21, 2026

Uh oh!

tgross35 commented Mar 26, 2026

Uh oh!

tgross35 commented Mar 27, 2026

Uh oh!

malezjaa commented Mar 28, 2026

Uh oh!

This comment has been minimized.

reddevilmidzy commented Mar 31, 2026

Uh oh!

rustbot commented Mar 31, 2026

Uh oh!

rustbot commented Mar 31, 2026

Uh oh!

This comment has been minimized.

matthiaskrgr commented Apr 3, 2026

Uh oh!

malezjaa commented Apr 3, 2026

Uh oh!

tgross35 commented Apr 3, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

malezjaa commented Apr 3, 2026

Uh oh!

tgross35 commented Apr 3, 2026

Uh oh!

tgross35 commented Apr 4, 2026

Uh oh!

This comment has been minimized.

rust-bors bot commented Apr 4, 2026

Uh oh!

tgross35 commented Apr 4, 2026

Uh oh!

rust-bors bot commented Apr 4, 2026

Uh oh!

Uh oh!

malezjaa commented Apr 4, 2026

Uh oh!

tgross35 commented Apr 4, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

8 participants

malezjaa commented Mar 18, 2026 •

edited

Loading

tgross35 commented Apr 3, 2026 •

edited

Loading