Add performance notes for the floating-point round method - #161743

joonas-001 · 2026-08-25T11:50:07Z

This update has revised the documentation for f32::round and f64::round, stating that round_ties_even typically offers better performance on most hardware platforms, and reminding readers that the rounding rules at the midpoint are different for the two methods. This update addresses the unfinished documentation task in issue #55107.

rustbot · 2026-08-25T11:50:13Z

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joonas-001 · 2026-09-18T05:09:58Z

@rustbot reroll

JohnTitor

Thanks! @bors r+ rollup

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rust-bors · 2026-09-19T01:00:58Z

📌 Commit 746c872 has been approved by JohnTitor

It is now in the queue for this repository.

…ocs, r=JohnTitor Add performance notes for the floating-point round method This update has revised the documentation for f32::round and f64::round, stating that round_ties_even typically offers better performance on most hardware platforms, and reminding readers that the rounding rules at the midpoint are different for the two methods. This update addresses the unfinished documentation task in issue rust-lang#55107.

Rollup of 18 pull requests Successful merges: - #162499 (`rustc_codegen_gcc` subtree update) - #161424 (implement `VaArgSafe` for `f128`) - #161777 (Add Natvis visualiser and debuginfo tests for `f128`) - #162506 (Avoid suggesting imports of traits declared inside fn bodies) - #162591 (Move parse error recovery for expression operators "out of line" & refactor in the area) - #162669 ([rustdoc] Correctly handle intra-doc links on inlined same item with different names) - #162733 (Add useful APIs to `Unique(Arc|Rc)`) - #162913 (Refactor LivenessResults into LivenessComputation, without typeck) - #162950 (More AST lowering cleanups) - #162964 (Update `browser-ui-test` version to `0.25.2`) - #162979 (mark `f128` as reliable on `powerpc64` with `+vsx`) - #161743 (Add performance notes for the floating-point round method) - #162797 (yeet AliasConstKind::opt_def_id) - #162836 (Ping T-libs-ping instead of T-libs-fcp for backports) - #162873 (Adjust `bug!`/`span_bug!` emission) - #162875 (Add .seek_read_exact(), .seek_write_all() to std::os::windows::fs::FileExt) - #162956 (Add missing `#[repr(C)]` in UI, codegen and assembly tests) - #162981 (rustc-dev-guide subtree update) Failed merges: - #162177 (Properly implement the gpu-kernel ABI for amdgpu)

…ocs, r=JohnTitor Add performance notes for the floating-point round method This update has revised the documentation for f32::round and f64::round, stating that round_ties_even typically offers better performance on most hardware platforms, and reminding readers that the rounding rules at the midpoint are different for the two methods. This update addresses the unfinished documentation task in issue rust-lang#55107.

…uwer Rollup of 22 pull requests Successful merges: - #163001 (Temporarily disable `test-x86_64-fuchsia`) - #162880 (Mini optimization in `rustc_hir_typeck::upvar::restrict_precision_for_drop_types`) - #161424 (implement `VaArgSafe` for `f128`) - #161777 (Add Natvis visualiser and debuginfo tests for `f128`) - #162506 (Avoid suggesting imports of traits declared inside fn bodies) - #162591 (Move parse error recovery for expression operators "out of line" & refactor in the area) - #162669 ([rustdoc] Correctly handle intra-doc links on inlined same item with different names) - #162733 (Add useful APIs to `Unique(Arc|Rc)`) - #162913 (Refactor LivenessResults into LivenessComputation, without typeck) - #162924 (Remove applying inline attributes at the callsite) - #162940 (Use spawned `SBDebugger` instance) - #162950 (More AST lowering cleanups) - #162964 (Update `browser-ui-test` version to `0.25.2`) - #162979 (mark `f128` as reliable on `powerpc64` with `+vsx`) - #161743 (Add performance notes for the floating-point round method) - #162797 (yeet AliasConstKind::opt_def_id) - #162836 (Ping T-libs-ping instead of T-libs-fcp for backports) - #162873 (Adjust `bug!`/`span_bug!` emission) - #162956 (Add missing `#[repr(C)]` in UI, codegen and assembly tests) - #162971 (libtest harness: avoid 'extern crate test' with custom runner) - #162981 (rustc-dev-guide subtree update) - #162985 (Error on invalid placements for unstable attributes)

Rollup merge of #161743 - joonas-001:codex/round-ties-even-docs, r=JohnTitor Add performance notes for the floating-point round method This update has revised the documentation for f32::round and f64::round, stating that round_ties_even typically offers better performance on most hardware platforms, and reminding readers that the rounding rules at the midpoint are different for the two methods. This update addresses the unfinished documentation task in issue #55107.

…uwer Rollup of 22 pull requests Successful merges: - rust-lang/rust#163001 (Temporarily disable `test-x86_64-fuchsia`) - rust-lang/rust#162880 (Mini optimization in `rustc_hir_typeck::upvar::restrict_precision_for_drop_types`) - rust-lang/rust#161424 (implement `VaArgSafe` for `f128`) - rust-lang/rust#161777 (Add Natvis visualiser and debuginfo tests for `f128`) - rust-lang/rust#162506 (Avoid suggesting imports of traits declared inside fn bodies) - rust-lang/rust#162591 (Move parse error recovery for expression operators "out of line" & refactor in the area) - rust-lang/rust#162669 ([rustdoc] Correctly handle intra-doc links on inlined same item with different names) - rust-lang/rust#162733 (Add useful APIs to `Unique(Arc|Rc)`) - rust-lang/rust#162913 (Refactor LivenessResults into LivenessComputation, without typeck) - rust-lang/rust#162924 (Remove applying inline attributes at the callsite) - rust-lang/rust#162940 (Use spawned `SBDebugger` instance) - rust-lang/rust#162950 (More AST lowering cleanups) - rust-lang/rust#162964 (Update `browser-ui-test` version to `0.25.2`) - rust-lang/rust#162979 (mark `f128` as reliable on `powerpc64` with `+vsx`) - rust-lang/rust#161743 (Add performance notes for the floating-point round method) - rust-lang/rust#162797 (yeet AliasConstKind::opt_def_id) - rust-lang/rust#162836 (Ping T-libs-ping instead of T-libs-fcp for backports) - rust-lang/rust#162873 (Adjust `bug!`/`span_bug!` emission) - rust-lang/rust#162956 (Add missing `#[repr(C)]` in UI, codegen and assembly tests) - rust-lang/rust#162971 (libtest harness: avoid 'extern crate test' with custom runner) - rust-lang/rust#162981 (rustc-dev-guide subtree update) - rust-lang/rust#162985 (Error on invalid placements for unstable attributes)

Add performance notes for the floating-point round method

746c872

rustbot assigned ChrisDenton Aug 25, 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 Aug 25, 2026

rustbot assigned JohnTitor and unassigned ChrisDenton Sep 18, 2026

JohnTitor approved these changes Sep 19, 2026

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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-review Status: Awaiting review from the assignee but also interested parties. labels Sep 19, 2026

Zalathar mentioned this pull request Sep 19, 2026

Rollup of 18 pull requests #162996

Closed

This was referenced Sep 19, 2026

Rollup of 20 pull requests #163000

Closed

Rollup of 22 pull requests #163002

Merged

rust-bors Bot merged commit f9e4ef3 into rust-lang:main Sep 19, 2026
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rustbot added this to the 1.100.0 milestone Sep 19, 2026

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Add performance notes for the floating-point round method - #161743