fmt of non-decimal radix untangled #143730

pascaldekloe · 2025-07-10T12:51:01Z

Have the implementation match its decimal counterpart.

Digit table instead of conversion functions
Correct buffer size per radix
Elimination of dead code for negative
No trait abstraction for integers

Original Performance

    fmt::write_10ints_bin                                                393.03ns/iter      +/- 1.41
    fmt::write_10ints_hex                                                316.84ns/iter      +/- 1.49
    fmt::write_10ints_oct                                                327.16ns/iter      +/- 0.46

Patched Performance

    fmt::write_10ints_bin                                                392.31ns/iter      +/- 3.05
    fmt::write_10ints_hex                                                302.41ns/iter      +/- 5.48
    fmt::write_10ints_oct                                                322.01ns/iter      +/- 3.82

r? tgross35

pascaldekloe · 2025-07-10T12:58:31Z

https://rust.godbolt.org/z/K1hWxa7dP

bors · 2025-07-17T08:43:24Z

☔ The latest upstream changes (presumably #144044) made this pull request unmergeable. Please resolve the merge conflicts.

pascaldekloe · 2025-07-18T13:37:22Z

Can you either have a look or reassign @tgross35? Got a followup pending on this one...

tgross35 · 2025-07-18T19:02:16Z

I'll reassign for now, but if nobody beats me to it I'll take a look on Monday

r? libs

(leaving myself assigned so it stays on my list)

tgross35 · 2025-07-18T21:14:44Z

By the way; if you are interested, we could use some int (and float) formatting and parsing benchmarks at https://github.com/rust-lang/rustc-perf/blob/2120e3b7b8996e96858b88edefea371679a3d415/collector/runtime-benchmarks/fmt/src/main.rs (I just learned that is possible), which would mean they get run as part of our pretty extensive perf infra rather than you needing to post the results of local runs.

pascaldekloe · 2025-07-18T21:56:23Z

Interesting indeed @tgross35. The specialized benchmarks we have at the moment (such as write_u8_min and write_u64_max) won't scale. Think about how many benchmarks we need for fmt::LowerExp with edge cases on alignment and precision. I am curious to hear what you think of the _10ints_ concept in this patch. The idea is to have a balanced mix of common cases.

tgross35

Few notes, haven't looked at patches 3 & 4 yet

library/core/src/fmt/num.rs

library/coretests/benches/fmt.rs

…t output

tgross35

Guess it's still on me, but this looks pretty good! Just a few small things

library/core/src/fmt/num.rs

* correct buffer size * no trait abstraction * similar to decimal

tgross35 · 2025-08-12T19:06:19Z

@bors2 try jobs=x86_64-gnu-llvm-19-3

r=me with that passing

fmt of non-decimal radix untangled try-job: x86_64-gnu-llvm-19-3

rust-bors · 2025-08-12T20:56:47Z

💔 Test for 59e4e19 failed: CI. Failed jobs:

try - x86_64-gnu-llvm-19-3 (web logs, extended logs)

tgross35 · 2025-08-12T21:00:49Z

Huh, does it get &T sometimes and just T others?

You can check that config locally with rust.std-features = ["optimize_for_size"] in your bootstrap.toml

pascaldekloe · 2025-08-16T21:28:03Z

You can check that config locally with rust.std-features = ["optimize_for_size"] in your bootstrap.toml

Apparently such changes don't always get picked up by ./x test. I will dig in deeper into why at some point if time permits.

tgross35 · 2025-08-18T18:59:38Z

@bors2 try jobs=x86_64-gnu-llvm-19-3

fmt of non-decimal radix untangled try-job: x86_64-gnu-llvm-19-3

rust-bors · 2025-08-18T21:03:13Z

☀️ Try build successful (CI)
Build commit: 054eb81 (054eb81f0211a6054e03c271809d347281601102, parent: 239e8b1b47b34120287ec36b33228c1e177f0c38)

tgross35 · 2025-08-18T23:03:15Z

Thanks for the fix!

@bors r+

Apparently such changes don't always get picked up by ./x test. I will dig in deeper into why at some point if time permits.

Maybe just bring this up the #t-infra/bootstrap Zulip, somebody may know a better idea of why

bors · 2025-08-18T23:03:18Z

📌 Commit 1f77424 has been approved by tgross35

It is now in the queue for this repository.

Noratrieb · 2025-08-19T05:55:44Z

@bors rollup=maybe

…oss35 fmt of non-decimal radix untangled Have the implementation match its decimal counterpart. * Digit table instead of conversion functions * Correct buffer size per radix * Elimination of dead code for negative * No trait abstraction for integers #### Original Performance ``` fmt::write_10ints_bin 393.03ns/iter +/- 1.41 fmt::write_10ints_hex 316.84ns/iter +/- 1.49 fmt::write_10ints_oct 327.16ns/iter +/- 0.46 ``` #### Patched Performance ``` fmt::write_10ints_bin 392.31ns/iter +/- 3.05 fmt::write_10ints_hex 302.41ns/iter +/- 5.48 fmt::write_10ints_oct 322.01ns/iter +/- 3.82 ``` r? tgross35

Rollup of 15 pull requests Successful merges: - #139345 (Extend `QueryStability` to handle `IntoIterator` implementations) - #140740 (Add `-Zindirect-branch-cs-prefix`) - #142079 (nll-relate: improve hr opaque types support) - #142938 (implement std::fs::set_permissions_nofollow on unix) - #143730 (fmt of non-decimal radix untangled) - #144767 (Correct some grammar in integer documentation) - #144906 (Require approval from t-infra instead of t-release on tier bumps) - #144983 (Rehome 37 `tests/ui/issues/` tests to other subdirectories under `tests/ui/`) - #145025 (run spellcheck as a tidy extra check in ci) - #145099 (rustc_target: Add the `32s` target feature for LoongArch) - #145166 (suggest using `pub(crate)` for E0364) - #145255 (dec2flt: Provide more valid inputs examples) - #145306 (Add tracing to various miscellaneous functions) - #145336 (Hide docs for `core::unicode`) - #145585 (Miri: fix handling of in-place argument and return place handling) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #143730 - pascaldekloe:fmt-radix-trim, r=tgross35 fmt of non-decimal radix untangled Have the implementation match its decimal counterpart. * Digit table instead of conversion functions * Correct buffer size per radix * Elimination of dead code for negative * No trait abstraction for integers #### Original Performance ``` fmt::write_10ints_bin 393.03ns/iter +/- 1.41 fmt::write_10ints_hex 316.84ns/iter +/- 1.49 fmt::write_10ints_oct 327.16ns/iter +/- 0.46 ``` #### Patched Performance ``` fmt::write_10ints_bin 392.31ns/iter +/- 3.05 fmt::write_10ints_hex 302.41ns/iter +/- 5.48 fmt::write_10ints_oct 322.01ns/iter +/- 3.82 ``` r? tgross35

Rollup of 15 pull requests Successful merges: - rust-lang#139345 (Extend `QueryStability` to handle `IntoIterator` implementations) - rust-lang#140740 (Add `-Zindirect-branch-cs-prefix`) - rust-lang#142079 (nll-relate: improve hr opaque types support) - rust-lang#142938 (implement std::fs::set_permissions_nofollow on unix) - rust-lang#143730 (fmt of non-decimal radix untangled) - rust-lang#144767 (Correct some grammar in integer documentation) - rust-lang#144906 (Require approval from t-infra instead of t-release on tier bumps) - rust-lang#144983 (Rehome 37 `tests/ui/issues/` tests to other subdirectories under `tests/ui/`) - rust-lang#145025 (run spellcheck as a tidy extra check in ci) - rust-lang#145099 (rustc_target: Add the `32s` target feature for LoongArch) - rust-lang#145166 (suggest using `pub(crate)` for E0364) - rust-lang#145255 (dec2flt: Provide more valid inputs examples) - rust-lang#145306 (Add tracing to various miscellaneous functions) - rust-lang#145336 (Hide docs for `core::unicode`) - rust-lang#145585 (Miri: fix handling of in-place argument and return place handling) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 15 pull requests Successful merges: - rust-lang/rust#139345 (Extend `QueryStability` to handle `IntoIterator` implementations) - rust-lang/rust#140740 (Add `-Zindirect-branch-cs-prefix`) - rust-lang/rust#142079 (nll-relate: improve hr opaque types support) - rust-lang/rust#142938 (implement std::fs::set_permissions_nofollow on unix) - rust-lang/rust#143730 (fmt of non-decimal radix untangled) - rust-lang/rust#144767 (Correct some grammar in integer documentation) - rust-lang/rust#144906 (Require approval from t-infra instead of t-release on tier bumps) - rust-lang/rust#144983 (Rehome 37 `tests/ui/issues/` tests to other subdirectories under `tests/ui/`) - rust-lang/rust#145025 (run spellcheck as a tidy extra check in ci) - rust-lang/rust#145099 (rustc_target: Add the `32s` target feature for LoongArch) - rust-lang/rust#145166 (suggest using `pub(crate)` for E0364) - rust-lang/rust#145255 (dec2flt: Provide more valid inputs examples) - rust-lang/rust#145306 (Add tracing to various miscellaneous functions) - rust-lang/rust#145336 (Hide docs for `core::unicode`) - rust-lang/rust#145585 (Miri: fix handling of in-place argument and return place handling) r? `@ghost` `@rustbot` modify labels: rollup

…oss35 fmt of non-decimal radix untangled Have the implementation match its decimal counterpart. * Digit table instead of conversion functions * Correct buffer size per radix * Elimination of dead code for negative * No trait abstraction for integers #### Original Performance ``` fmt::write_10ints_bin 393.03ns/iter +/- 1.41 fmt::write_10ints_hex 316.84ns/iter +/- 1.49 fmt::write_10ints_oct 327.16ns/iter +/- 0.46 ``` #### Patched Performance ``` fmt::write_10ints_bin 392.31ns/iter +/- 3.05 fmt::write_10ints_hex 302.41ns/iter +/- 5.48 fmt::write_10ints_oct 322.01ns/iter +/- 3.82 ``` r? tgross35

rustbot assigned tgross35 Jul 10, 2025

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 Jul 10, 2025

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pascaldekloe added 2 commits July 25, 2025 16:02

fmt of non-decimals is always non-negative due to the two's-complemen…

c6ac515

…t output

fmt benchmarks for binary, octal and hex

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fmt with table lookup for binary, octal and hex

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* correct buffer size * no trait abstraction * similar to decimal

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Auto merge of #143730 - pascaldekloe:fmt-radix-trim, r=<try>

59e4e19

fmt of non-decimal radix untangled try-job: x86_64-gnu-llvm-19-3

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fmt::DisplayInt abstraction obsolete with better macro

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rust-bors bot added a commit that referenced this pull request Aug 18, 2025

Auto merge of #143730 - pascaldekloe:fmt-radix-trim, r=<try>

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fmt of non-decimal radix untangled try-job: x86_64-gnu-llvm-19-3

bors 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 Aug 18, 2025

This was referenced Aug 19, 2025

Rollup of 17 pull requests #145598

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Rollup of 15 pull requests #145599

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bors merged commit 4327e69 into rust-lang:master Aug 19, 2025
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rustbot added this to the 1.91.0 milestone Aug 19, 2025

fmt of non-decimal radix untangled #143730

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pascaldekloe commented Jul 10, 2025

Original Performance

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