Reorder `lto` options in profiles.md #15841

smoelius · 2025-08-15T17:13:08Z

Aside from false, the lto options seem to be ordered from "most optimizing" to "least optimizing".

If this interpretation is correct, then I think false should go between thin and off.

cc: @ehuss (who I think wrote that text)

rustbot · 2025-08-15T17:13:13Z

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weihanglo

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src/doc/src/reference/profiles.md

Co-authored-by: Weihang Lo <[email protected]>

bjorn3 · 2025-08-17T20:42:21Z

src/doc/src/reference/profiles.md

@@ -166,16 +166,16 @@ The `lto` setting controls `rustc`'s [`-C lto`], [`-C linker-plugin-lto`], and
 LTO can produce better optimized code, using whole-program analysis, at the cost
 of longer linking time.

-The valid options are:
+The valid options from most to least optimizing are:


As I understand it, this is not true in the general case. fat LTO can produce faster executables than ThinLTO and even if it doesn't, it is often very close. ThinLTO just generally produces a bit bigger executables.

So in terms of executable performance,

is it fat >= ThinLTO or ThinLTO >= fat, or hard to say?

As I understand it, it could be either way nowadays. There is probably still some bias for fat LTO producing faster executables than ThinLTO though.

I see. Thanks for pointing it out!

There is another similar ongoing in rust-lang/rust rust-lang/rust#145533. Do you think we should r- that, and revert this PR as well?

I think the order makes sense. I just think we should not explicitly say "from most to least optimizing" here.

Update cargo 28 commits in 840b83a10fb0e039a83f4d70ad032892c287570a..71eb84f21aef43c07580c6aed6f806a6299f5042 2025-07-30 13:59:19 +0000 to 2025-08-17 17:18:56 +0000 - update tests to match lint message changes from #140794 (rust-lang/cargo#15849) - chore: downgrade to [email protected] (rust-lang/cargo#15851) - Reorder `lto` options in profiles.md (rust-lang/cargo#15841) - feat(unstable): add -Zbuild-analysis unstable feature (rust-lang/cargo#15845) - refactor(unstable): group stabilized features (rust-lang/cargo#15846) - Fixes error while running the cargo clippy --all-targets -- -D warning (rust-lang/cargo#15843) - Clarify that `cargo doc --no-deps` is cumulative and won’t delete prev (rust-lang/cargo#15800) - docs: Formatting and cross-linking to build-dir/target-dir docs (rust-lang/cargo#15840) - Stabilize `build.build-dir` (rust-lang/cargo#15833) - make resolve features public for cargo-as-a-library (rust-lang/cargo#15835) - chore(deps): bump slab from 0.4.10 to 0.4.11 (rust-lang/cargo#15832) - chore: remove x86_64-apple-darwin from CI and tests (rust-lang/cargo#15831) - chore(deps): update msrv (3 versions) to v1.87 (rust-lang/cargo#15819) - perf(package): Always reuse the workspace's target-dir (rust-lang/cargo#15783) - More helpful error for invalid cargo-features = [] (rust-lang/cargo#15781) - Add initial integration for `--json=timings` behing `-Zsection-timings` (rust-lang/cargo#15780) - add is_inherited methods to InheritableDependency and InheritableField (rust-lang/cargo#15828) - chore(deps): update compatible (rust-lang/cargo#15804) - docs(unstable): Link out to the Plumbing commands effort (rust-lang/cargo#15821) - chore(deps): update cargo-semver-checks to v0.43.0 (rust-lang/cargo#15825) - test(build-std): relax the thread name assertion (rust-lang/cargo#15822) - chore(deps): update msrv (1 version) to v1.89 (rust-lang/cargo#15815) - Update semver tests for 1.89 (rust-lang/cargo#15816) - Accessing each build script's `OUT_DIR` and in the correct order (rust-lang/cargo#15776) - chore: bump to 0.92.0; update changelog (rust-lang/cargo#15807) - docs: `-Zpackage-workspace` has been stabilized (rust-lang/cargo#15808) - chore(deps): update rust crate cargo_metadata to 0.21.0 (rust-lang/cargo#15795) - docs(build-rs): Fix broken intra-doc links (rust-lang/cargo#15810)

Reorder `lto` options from most to least optimizing This is a follow up to rust-lang/cargo#15841. `@weihanglo` pointed out the original order of the `lto` options in the Cargo book was consistent with https://doc.rust-lang.org/rustc/codegen-options/index.html?highlight=lto#lto. The options in the Cargo book have since been reordered. This PR keeps the two references consistent.

There is no clear winner between fat LTO and ThinLTO, so don't say "from most to least optimizing" here. See rust-lang#15841 (comment)

Update cargo 28 commits in 840b83a10fb0e039a83f4d70ad032892c287570a..71eb84f21aef43c07580c6aed6f806a6299f5042 2025-07-30 13:59:19 +0000 to 2025-08-17 17:18:56 +0000 - update tests to match lint message changes from #140794 (rust-lang/cargo#15849) - chore: downgrade to [email protected] (rust-lang/cargo#15851) - Reorder `lto` options in profiles.md (rust-lang/cargo#15841) - feat(unstable): add -Zbuild-analysis unstable feature (rust-lang/cargo#15845) - refactor(unstable): group stabilized features (rust-lang/cargo#15846) - Fixes error while running the cargo clippy --all-targets -- -D warning (rust-lang/cargo#15843) - Clarify that `cargo doc --no-deps` is cumulative and won’t delete prev (rust-lang/cargo#15800) - docs: Formatting and cross-linking to build-dir/target-dir docs (rust-lang/cargo#15840) - Stabilize `build.build-dir` (rust-lang/cargo#15833) - make resolve features public for cargo-as-a-library (rust-lang/cargo#15835) - chore(deps): bump slab from 0.4.10 to 0.4.11 (rust-lang/cargo#15832) - chore: remove x86_64-apple-darwin from CI and tests (rust-lang/cargo#15831) - chore(deps): update msrv (3 versions) to v1.87 (rust-lang/cargo#15819) - perf(package): Always reuse the workspace's target-dir (rust-lang/cargo#15783) - More helpful error for invalid cargo-features = [] (rust-lang/cargo#15781) - Add initial integration for `--json=timings` behing `-Zsection-timings` (rust-lang/cargo#15780) - add is_inherited methods to InheritableDependency and InheritableField (rust-lang/cargo#15828) - chore(deps): update compatible (rust-lang/cargo#15804) - docs(unstable): Link out to the Plumbing commands effort (rust-lang/cargo#15821) - chore(deps): update cargo-semver-checks to v0.43.0 (rust-lang/cargo#15825) - test(build-std): relax the thread name assertion (rust-lang/cargo#15822) - chore(deps): update msrv (1 version) to v1.89 (rust-lang/cargo#15815) - Update semver tests for 1.89 (rust-lang/cargo#15816) - Accessing each build script's `OUT_DIR` and in the correct order (rust-lang/cargo#15776) - chore: bump to 0.92.0; update changelog (rust-lang/cargo#15807) - docs: `-Zpackage-workspace` has been stabilized (rust-lang/cargo#15808) - chore(deps): update rust crate cargo_metadata to 0.21.0 (rust-lang/cargo#15795) - docs(build-rs): Fix broken intra-doc links (rust-lang/cargo#15810)

Reorder `lto` options from most to least optimizing This is a follow up to rust-lang/cargo#15841. ``@weihanglo`` pointed out the original order of the `lto` options in the Cargo book was consistent with https://doc.rust-lang.org/rustc/codegen-options/index.html?highlight=lto#lto. The options in the Cargo book have since been reordered. This PR keeps the two references consistent.

Reorder `lto` options from most to least optimizing This is a follow up to rust-lang/cargo#15841. ```@weihanglo``` pointed out the original order of the `lto` options in the Cargo book was consistent with https://doc.rust-lang.org/rustc/codegen-options/index.html?highlight=lto#lto. The options in the Cargo book have since been reordered. This PR keeps the two references consistent.

Update cargo 28 commits in 840b83a10fb0e039a83f4d70ad032892c287570a..71eb84f21aef43c07580c6aed6f806a6299f5042 2025-07-30 13:59:19 +0000 to 2025-08-17 17:18:56 +0000 - update tests to match lint message changes from #140794 (rust-lang/cargo#15849) - chore: downgrade to [email protected] (rust-lang/cargo#15851) - Reorder `lto` options in profiles.md (rust-lang/cargo#15841) - feat(unstable): add -Zbuild-analysis unstable feature (rust-lang/cargo#15845) - refactor(unstable): group stabilized features (rust-lang/cargo#15846) - Fixes error while running the cargo clippy --all-targets -- -D warning (rust-lang/cargo#15843) - Clarify that `cargo doc --no-deps` is cumulative and won’t delete prev (rust-lang/cargo#15800) - docs: Formatting and cross-linking to build-dir/target-dir docs (rust-lang/cargo#15840) - Stabilize `build.build-dir` (rust-lang/cargo#15833) - make resolve features public for cargo-as-a-library (rust-lang/cargo#15835) - chore(deps): bump slab from 0.4.10 to 0.4.11 (rust-lang/cargo#15832) - chore: remove x86_64-apple-darwin from CI and tests (rust-lang/cargo#15831) - chore(deps): update msrv (3 versions) to v1.87 (rust-lang/cargo#15819) - perf(package): Always reuse the workspace's target-dir (rust-lang/cargo#15783) - More helpful error for invalid cargo-features = [] (rust-lang/cargo#15781) - Add initial integration for `--json=timings` behing `-Zsection-timings` (rust-lang/cargo#15780) - add is_inherited methods to InheritableDependency and InheritableField (rust-lang/cargo#15828) - chore(deps): update compatible (rust-lang/cargo#15804) - docs(unstable): Link out to the Plumbing commands effort (rust-lang/cargo#15821) - chore(deps): update cargo-semver-checks to v0.43.0 (rust-lang/cargo#15825) - test(build-std): relax the thread name assertion (rust-lang/cargo#15822) - chore(deps): update msrv (1 version) to v1.89 (rust-lang/cargo#15815) - Update semver tests for 1.89 (rust-lang/cargo#15816) - Accessing each build script's `OUT_DIR` and in the correct order (rust-lang/cargo#15776) - chore: bump to 0.92.0; update changelog (rust-lang/cargo#15807) - docs: `-Zpackage-workspace` has been stabilized (rust-lang/cargo#15808) - chore(deps): update rust crate cargo_metadata to 0.21.0 (rust-lang/cargo#15795) - docs(build-rs): Fix broken intra-doc links (rust-lang/cargo#15810)

…15855) There is no clear winner between fat LTO and ThinLTO, so don't say "from most to least optimizing" here. See #15841 (comment)

Reorder `lto` options from most to least optimizing This is a follow up to rust-lang/cargo#15841. `@weihanglo` pointed out the original order of the `lto` options in the Cargo book was consistent with https://doc.rust-lang.org/rustc/codegen-options/index.html?highlight=lto#lto. The options in the Cargo book have since been reordered. This PR keeps the two references consistent.

Reorder `lto` options from most to least optimizing This is a follow up to rust-lang/cargo#15841. ``@weihanglo`` pointed out the original order of the `lto` options in the Cargo book was consistent with https://doc.rust-lang.org/rustc/codegen-options/index.html?highlight=lto#lto. The options in the Cargo book have since been reordered. This PR keeps the two references consistent.

Reorder `lto` options from most to least optimizing This is a follow up to rust-lang/cargo#15841. `@weihanglo` pointed out the original order of the `lto` options in the Cargo book was consistent with https://doc.rust-lang.org/rustc/codegen-options/index.html?highlight=lto#lto. The options in the Cargo book have since been reordered. This PR keeps the two references consistent.

Rollup merge of #145533 - smoelius:patch-2, r=lqd Reorder `lto` options from most to least optimizing This is a follow up to rust-lang/cargo#15841. `@weihanglo` pointed out the original order of the `lto` options in the Cargo book was consistent with https://doc.rust-lang.org/rustc/codegen-options/index.html?highlight=lto#lto. The options in the Cargo book have since been reordered. This PR keeps the two references consistent.

Update cargo 28 commits in 840b83a10fb0e039a83f4d70ad032892c287570a..71eb84f21aef43c07580c6aed6f806a6299f5042 2025-07-30 13:59:19 +0000 to 2025-08-17 17:18:56 +0000 - update tests to match lint message changes from rust-lang/rust#140794 (rust-lang/cargo#15849) - chore: downgrade to [email protected] (rust-lang/cargo#15851) - Reorder `lto` options in profiles.md (rust-lang/cargo#15841) - feat(unstable): add -Zbuild-analysis unstable feature (rust-lang/cargo#15845) - refactor(unstable): group stabilized features (rust-lang/cargo#15846) - Fixes error while running the cargo clippy --all-targets -- -D warning (rust-lang/cargo#15843) - Clarify that `cargo doc --no-deps` is cumulative and won’t delete prev (rust-lang/cargo#15800) - docs: Formatting and cross-linking to build-dir/target-dir docs (rust-lang/cargo#15840) - Stabilize `build.build-dir` (rust-lang/cargo#15833) - make resolve features public for cargo-as-a-library (rust-lang/cargo#15835) - chore(deps): bump slab from 0.4.10 to 0.4.11 (rust-lang/cargo#15832) - chore: remove x86_64-apple-darwin from CI and tests (rust-lang/cargo#15831) - chore(deps): update msrv (3 versions) to v1.87 (rust-lang/cargo#15819) - perf(package): Always reuse the workspace's target-dir (rust-lang/cargo#15783) - More helpful error for invalid cargo-features = [] (rust-lang/cargo#15781) - Add initial integration for `--json=timings` behing `-Zsection-timings` (rust-lang/cargo#15780) - add is_inherited methods to InheritableDependency and InheritableField (rust-lang/cargo#15828) - chore(deps): update compatible (rust-lang/cargo#15804) - docs(unstable): Link out to the Plumbing commands effort (rust-lang/cargo#15821) - chore(deps): update cargo-semver-checks to v0.43.0 (rust-lang/cargo#15825) - test(build-std): relax the thread name assertion (rust-lang/cargo#15822) - chore(deps): update msrv (1 version) to v1.89 (rust-lang/cargo#15815) - Update semver tests for 1.89 (rust-lang/cargo#15816) - Accessing each build script's `OUT_DIR` and in the correct order (rust-lang/cargo#15776) - chore: bump to 0.92.0; update changelog (rust-lang/cargo#15807) - docs: `-Zpackage-workspace` has been stabilized (rust-lang/cargo#15808) - chore(deps): update rust crate cargo_metadata to 0.21.0 (rust-lang/cargo#15795) - docs(build-rs): Fix broken intra-doc links (rust-lang/cargo#15810)

Reorder `lto` options from most to least optimizing This is a follow up to rust-lang/cargo#15841. `@weihanglo` pointed out the original order of the `lto` options in the Cargo book was consistent with https://doc.rust-lang.org/rustc/codegen-options/index.html?highlight=lto#lto. The options in the Cargo book have since been reordered. This PR keeps the two references consistent.

Reorder lto options in profiles.md

0b34dd3

rustbot assigned epage Aug 15, 2025

rustbot added A-documenting-cargo-itself Area: Cargo's documentation S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Aug 15, 2025

weihanglo reviewed Aug 17, 2025

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Mention ordering rationale in profiles.md

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Co-authored-by: Weihang Lo <[email protected]>

weihanglo approved these changes Aug 17, 2025

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weihanglo added this pull request to the merge queue Aug 17, 2025

Merged via the queue into rust-lang:master with commit eae8d0d Aug 17, 2025
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smoelius mentioned this pull request Aug 17, 2025

Reorder lto options from most to least optimizing rust-lang/rust#145533

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weihanglo mentioned this pull request Aug 17, 2025

Update cargo rust-lang/rust#145478

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bjorn3 reviewed Aug 17, 2025

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weihanglo mentioned this pull request Aug 18, 2025

docs(profile): revert wrong statement of lto options' optimization #15855

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smoelius deleted the patch-1 branch August 19, 2025 00:32

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