Regression test for const promotion with Option<Ordering> by borsakv · Pull Request #145651 · rust-lang/rust

borsakv · 2025-08-20T10:20:15Z

https://rust.godbolt.org/z/EjxqE8WcT

Add a regression test to ensure that comparing Option<Ordering> to
Some(Ordering::Equal) does not trigger unnecessary const promotion
in MIR.

Previously, inlined constants like Some(Ordering::Equal) would get
promoted, leading to more complex MIR and redundant LLVM IR checks.
This test verifies that both the direct form and the let-binding form
now generate equivalent, simplified MIR.

r? cjgillot

cjgillot

What we are testing here is not really the absence of promoted constants. What we want to test is that both versions produce the same optimized MIR.

tests/mir-opt/pre-codegen/const_promotion_option_ordering_eq.rs

rustbot · 2025-10-10T12:25:34Z

⚠️ Warning ⚠️

This PR is based on an upstream commit that is older than 28 days.

It's recommended to update your branch according to the rustc-dev-guide.

cjgillot · 2025-10-10T13:05:04Z

r=me once CI passes

cjgillot · 2025-10-10T14:03:32Z

@bors r+ rollup

bors · 2025-10-10T14:03:35Z

📌 Commit c86474c has been approved by cjgillot

It is now in the queue for this repository.

Rollup of 12 pull requests Successful merges: - #145651 (Regression test for const promotion with Option<Ordering>) - #145722 (implement Extend<{Group, Literal, Punct, Ident}> for TokenStream) - #146520 (Promote armv8r-none-eabihf target to Tier 2) - #146522 (Promote armv7a-none-eabihf to Tier 2) - #147289 (Mitigate `thread_local!` shadowing issues) - #147515 (Update rustc-perf submodule) - #147522 (compiletest: Use the same directive lines for EarlyProps and ignore/only/needs) - #147525 (Replace locals in debuginfo records during ref_prop and dest_prop) - #147544 (Remove StatementKind::Deinit.) - #147551 (remove `#[rustc_inherit_overflow_checks]` from `is_multiple_of`) - #147553 (Move `wasm32-wasip3` to the tier 3 table) - #147562 (Stabilize `NonZero<u*>::div_ceil`) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #145651 - borsakv:139093, r=cjgillot Regression test for const promotion with Option<Ordering> https://rust.godbolt.org/z/EjxqE8WcT Fixes #139093 Add a regression test to ensure that comparing `Option<Ordering>` to `Some(Ordering::Equal)` does not trigger unnecessary const promotion in MIR. Previously, inlined constants like `Some(Ordering::Equal)` would get promoted, leading to more complex MIR and redundant LLVM IR checks. This test verifies that both the direct form and the `let`-binding form now generate equivalent, simplified MIR. r? cjgillot

Rollup of 12 pull requests Successful merges: - rust-lang/rust#145651 (Regression test for const promotion with Option<Ordering>) - rust-lang/rust#145722 (implement Extend<{Group, Literal, Punct, Ident}> for TokenStream) - rust-lang/rust#146520 (Promote armv8r-none-eabihf target to Tier 2) - rust-lang/rust#146522 (Promote armv7a-none-eabihf to Tier 2) - rust-lang/rust#147289 (Mitigate `thread_local!` shadowing issues) - rust-lang/rust#147515 (Update rustc-perf submodule) - rust-lang/rust#147522 (compiletest: Use the same directive lines for EarlyProps and ignore/only/needs) - rust-lang/rust#147525 (Replace locals in debuginfo records during ref_prop and dest_prop) - rust-lang/rust#147544 (Remove StatementKind::Deinit.) - rust-lang/rust#147551 (remove `#[rustc_inherit_overflow_checks]` from `is_multiple_of`) - rust-lang/rust#147553 (Move `wasm32-wasip3` to the tier 3 table) - rust-lang/rust#147562 (Stabilize `NonZero<u*>::div_ceil`) r? `@ghost` `@rustbot` modify labels: rollup

Regression test for const promotion with Option<Ordering> https://rust.godbolt.org/z/EjxqE8WcT Fixes rust-lang#139093 Add a regression test to ensure that comparing `Option<Ordering>` to `Some(Ordering::Equal)` does not trigger unnecessary const promotion in MIR. Previously, inlined constants like `Some(Ordering::Equal)` would get promoted, leading to more complex MIR and redundant LLVM IR checks. This test verifies that both the direct form and the `let`-binding form now generate equivalent, simplified MIR. r? cjgillot

Rollup of 12 pull requests Successful merges: - rust-lang#145651 (Regression test for const promotion with Option<Ordering>) - rust-lang#145722 (implement Extend<{Group, Literal, Punct, Ident}> for TokenStream) - rust-lang#146520 (Promote armv8r-none-eabihf target to Tier 2) - rust-lang#146522 (Promote armv7a-none-eabihf to Tier 2) - rust-lang#147289 (Mitigate `thread_local!` shadowing issues) - rust-lang#147515 (Update rustc-perf submodule) - rust-lang#147522 (compiletest: Use the same directive lines for EarlyProps and ignore/only/needs) - rust-lang#147525 (Replace locals in debuginfo records during ref_prop and dest_prop) - rust-lang#147544 (Remove StatementKind::Deinit.) - rust-lang#147551 (remove `#[rustc_inherit_overflow_checks]` from `is_multiple_of`) - rust-lang#147553 (Move `wasm32-wasip3` to the tier 3 table) - rust-lang#147562 (Stabilize `NonZero<u*>::div_ceil`) r? `@ghost` `@rustbot` modify labels: rollup

Regression test for const promotion with Option<Ordering> https://rust.godbolt.org/z/EjxqE8WcT Fixes rust-lang#139093 Add a regression test to ensure that comparing `Option<Ordering>` to `Some(Ordering::Equal)` does not trigger unnecessary const promotion in MIR. Previously, inlined constants like `Some(Ordering::Equal)` would get promoted, leading to more complex MIR and redundant LLVM IR checks. This test verifies that both the direct form and the `let`-binding form now generate equivalent, simplified MIR. r? cjgillot

Rollup of 12 pull requests Successful merges: - rust-lang#145651 (Regression test for const promotion with Option<Ordering>) - rust-lang#145722 (implement Extend<{Group, Literal, Punct, Ident}> for TokenStream) - rust-lang#146520 (Promote armv8r-none-eabihf target to Tier 2) - rust-lang#146522 (Promote armv7a-none-eabihf to Tier 2) - rust-lang#147289 (Mitigate `thread_local!` shadowing issues) - rust-lang#147515 (Update rustc-perf submodule) - rust-lang#147522 (compiletest: Use the same directive lines for EarlyProps and ignore/only/needs) - rust-lang#147525 (Replace locals in debuginfo records during ref_prop and dest_prop) - rust-lang#147544 (Remove StatementKind::Deinit.) - rust-lang#147551 (remove `#[rustc_inherit_overflow_checks]` from `is_multiple_of`) - rust-lang#147553 (Move `wasm32-wasip3` to the tier 3 table) - rust-lang#147562 (Stabilize `NonZero<u*>::div_ceil`) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 12 pull requests Successful merges: - rust-lang/rust#145651 (Regression test for const promotion with Option<Ordering>) - rust-lang/rust#145722 (implement Extend<{Group, Literal, Punct, Ident}> for TokenStream) - rust-lang/rust#146520 (Promote armv8r-none-eabihf target to Tier 2) - rust-lang/rust#146522 (Promote armv7a-none-eabihf to Tier 2) - rust-lang/rust#147289 (Mitigate `thread_local!` shadowing issues) - rust-lang/rust#147515 (Update rustc-perf submodule) - rust-lang/rust#147522 (compiletest: Use the same directive lines for EarlyProps and ignore/only/needs) - rust-lang/rust#147525 (Replace locals in debuginfo records during ref_prop and dest_prop) - rust-lang/rust#147544 (Remove StatementKind::Deinit.) - rust-lang/rust#147551 (remove `#[rustc_inherit_overflow_checks]` from `is_multiple_of`) - rust-lang/rust#147553 (Move `wasm32-wasip3` to the tier 3 table) - rust-lang/rust#147562 (Stabilize `NonZero<u*>::div_ceil`) r? `@ghost` `@rustbot` modify labels: rollup

rustbot assigned cjgillot Aug 20, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Aug 20, 2025

This comment has been minimized.

Sign in to view

borsakv force-pushed the 139093 branch from 6e2b65d to 0c8b586 Compare August 20, 2025 10:26

cjgillot reviewed Aug 21, 2025

View reviewed changes

tests/mir-opt/pre-codegen/const_promotion_option_ordering_eq.rs Outdated Show resolved Hide resolved

cjgillot 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 Aug 24, 2025

Adding a regression test (const promotion with Option<Ordering>)

c86474c

borsakv force-pushed the 139093 branch from 0c8b586 to c86474c Compare October 10, 2025 12:25

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 Oct 10, 2025

dianqk mentioned this pull request Oct 10, 2025

Rollup of 12 pull requests #147574

Merged

bors merged commit 486fae1 into rust-lang:master Oct 11, 2025
10 checks passed

rustbot added this to the 1.92.0 milestone Oct 11, 2025

github-actions bot mentioned this pull request Oct 21, 2025

Toolchain upgrade to nightly-2026-02-09 flux-rs/flux#1345

Open

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Regression test for const promotion with Option<Ordering>#145651

Regression test for const promotion with Option<Ordering>#145651
bors merged 1 commit intorust-lang:masterfrom
borsakv:139093

borsakv commented Aug 20, 2025 •

edited by rustbot

Loading

Uh oh!

This comment has been minimized.

cjgillot left a comment

Uh oh!

Uh oh!

rustbot commented Oct 10, 2025

Uh oh!

cjgillot commented Oct 10, 2025

Uh oh!

cjgillot commented Oct 10, 2025

Uh oh!

bors commented Oct 10, 2025

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

Uh oh!

Conversation

borsakv commented Aug 20, 2025 • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

This comment has been minimized.

cjgillot left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

rustbot commented Oct 10, 2025

Uh oh!

cjgillot commented Oct 10, 2025

Uh oh!

cjgillot commented Oct 10, 2025

Uh oh!

bors commented Oct 10, 2025

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

borsakv commented Aug 20, 2025 •

edited by rustbot

Loading