Updated slice tests to pass for big endian hosts for `multiple-option-or-permutations.rs` by rwardd · Pull Request #151780 · rust-lang/rust

rwardd · 2026-01-28T12:21:35Z

It was discovered that the FileCheck tests when performing an Option::or operation on a slice was failing when tested on a big endian host.

The compiler explorer link is here outlining the codegen output differences - https://rust.godbolt.org/z/qdE7d3G4f

This MR relaxes the constraints for the *slice_u8 variants of the test (by changing CHECK-NEXT to CHECK-DAG), whilst still maintaining the check for the necessary or logic.

Huge thanks to @Gelbpunkt for identifying this issue! It has been confirmed that this fix passes on a big endian target now as well.

Closes #151718

rustbot · 2026-01-28T12:21:40Z

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rwardd · 2026-01-28T12:27:57Z

r? @scottmcm

Was hoping to get some feedback from yourself, hopefully this one is still semi-fresh in memory :)
(Original PR - #150564)

nikic · 2026-01-28T14:52:41Z

tests/codegen-llvm/issues/multiple-option-or-permutations.rs

-    // CHECK-NEXT: [[R:%.+]] = select i1 [[SOME_A]], i16 %0, i16 %1
-    // CHECK: ret i16 [[R]]
+    // CHECK-DAG: [[SOME_A:%.+]] = trunc i16 {{.*}} to i1
+    // CHECK-DAG: select i1 [[SOME_A]], i16 %0, i16 %1


I don't think the use of CHECK-DAG here makes sense, as these instructions can only occur in this order (one depends on the other). Possibly you meant just CHECK?

Yes, in retrospect CHECK-DAG isn't good here, I will refactor to use revisions and subsequently use LITTLE-NEXT, BIG-X.

scottmcm · 2026-01-28T16:12:46Z

tests/codegen-llvm/issues/multiple-option-or-permutations.rs

-    // CHECK: ret i16 [[R]]
+    // CHECK-DAG: [[SOME_A:%.+]] = trunc i16 {{.*}} to i1
+    // CHECK-DAG: select i1 [[SOME_A]], i16 %0, i16 %1
+    // CHECK: ret i16 {{.*}}


This change to not say what's being returned feels like it's just making it a worse test. Notably, sure it's passing, but you needed to do this because there's two selects in the BE version, and failing if the LE version started doing that is good if you ask me.

I think it'd be better to use revisions to make these LITTLE-NEXT and add separate BIG-WHATEVER checks for the big-endian versions if they're this different.

Agreed, when writing this I wasn't too happy that it wasn't exhaustively checking the BE output, whilst simultaneously making the LE test worse.

I'm currently working through using revisions, my current iteration looking like the following, using only-endian-big and ignore-endian-big to select the desired revision:

//@ revisions: LITTLE BIG //@ [BIG] only-endian-big //@ [LITTLE] ignore-endian-big

The only problem is that the only-endian-big doesn't exist in directive_names.rs, but it's still a valid directive according to the test directive docs.

Would it be appropriate to add only-endian-big to directive_names.rs in this PR?

rustbot · 2026-01-28T16:12:57Z

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

rustbot · 2026-02-08T05:06:39Z

Some changes occurred in src/tools/compiletest

cc @jieyouxu

rustbot · 2026-02-08T05:06:42Z

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.

rwardd · 2026-02-08T06:06:42Z

@rustbot ready

Apologies for the delay in fixing this, I have added only-endian-big to directive_names.rs to allow for conditional BIG and LITTLE revisions.

Gelbpunkt · 2026-02-14T01:11:25Z

Heya, just chiming in again to confirm that the updated version still passes tests on big endian hosts :)

Gelbpunkt · 2026-03-02T14:06:59Z

Gentle ping, the testsuite is still broken on big endian targets without this patch

nikic · 2026-03-02T14:21:35Z

Filed llvm/llvm-project#184131 for the missing optimization on big endian.

nikic · 2026-03-02T14:22:15Z

@bors r+

rust-bors · 2026-03-02T14:22:18Z

📌 Commit 5265ee0 has been approved by nikic

It is now in the queue for this repository.

@Gelbpunkt

…s, r=nikic Updated slice tests to pass for big endian hosts for `multiple-option-or-permutations.rs` It was discovered that the FileCheck tests when performing an `Option::or` operation on a slice was failing when tested on a big endian host. The compiler explorer link is here outlining the codegen output differences - https://rust.godbolt.org/z/qdE7d3G4f This MR relaxes the constraints for the `*slice_u8` variants of the test (by changing `CHECK-NEXT` to `CHECK-DAG`), whilst still maintaining the check for the necessary `or` logic. Huge thanks to @Gelbpunkt for identifying this issue! It has been confirmed that this fix passes on a big endian target now as well. Closes rust-lang#151718

…uwer Rollup of 5 pull requests Successful merges: - #153153 (add tests for thumb interworking) - #149328 (Add `String<A>` type with custom allocator parameter) - #151780 (Updated slice tests to pass for big endian hosts for `multiple-option-or-permutations.rs`) - #153015 (core: make atomic primitives type aliases of `Atomic<T>`) - #153292 (tests: codegen-llvm: vec-calloc: do not require the uwtable attribute) Failed merges: - #151864 (Implement AST -> HIR generics propagation in delegation)

@Gelbpunkt

…s, r=nikic Updated slice tests to pass for big endian hosts for `multiple-option-or-permutations.rs` It was discovered that the FileCheck tests when performing an `Option::or` operation on a slice was failing when tested on a big endian host. The compiler explorer link is here outlining the codegen output differences - https://rust.godbolt.org/z/qdE7d3G4f This MR relaxes the constraints for the `*slice_u8` variants of the test (by changing `CHECK-NEXT` to `CHECK-DAG`), whilst still maintaining the check for the necessary `or` logic. Huge thanks to @Gelbpunkt for identifying this issue! It has been confirmed that this fix passes on a big endian target now as well. Closes rust-lang#151718

…uwer Rollup of 9 pull requests Successful merges: - #153153 (add tests for thumb interworking) - #149328 (Add `String<A>` type with custom allocator parameter) - #151780 (Updated slice tests to pass for big endian hosts for `multiple-option-or-permutations.rs`) - #151962 (Fix next-solver ICE on PointeeSized goals) - #153015 (core: make atomic primitives type aliases of `Atomic<T>`) - #153161 (Rejig `rustc_with_all_queries!`) - #153191 ( don't emit `unused_results` lint for tuples of "trivial" types ) - #153273 (vec/mod.rs: add missing period in "ie." in docs) - #153292 (tests: codegen-llvm: vec-calloc: do not require the uwtable attribute)

@Gelbpunkt

…s, r=nikic Updated slice tests to pass for big endian hosts for `multiple-option-or-permutations.rs` It was discovered that the FileCheck tests when performing an `Option::or` operation on a slice was failing when tested on a big endian host. The compiler explorer link is here outlining the codegen output differences - https://rust.godbolt.org/z/qdE7d3G4f This MR relaxes the constraints for the `*slice_u8` variants of the test (by changing `CHECK-NEXT` to `CHECK-DAG`), whilst still maintaining the check for the necessary `or` logic. Huge thanks to @Gelbpunkt for identifying this issue! It has been confirmed that this fix passes on a big endian target now as well. Closes rust-lang#151718

…uwer Rollup of 11 pull requests Successful merges: - #153153 (add tests for thumb interworking) - #149328 (Add `String<A>` type with custom allocator parameter) - #151780 (Updated slice tests to pass for big endian hosts for `multiple-option-or-permutations.rs`) - #151962 (Fix next-solver ICE on PointeeSized goals) - #153015 (core: make atomic primitives type aliases of `Atomic<T>`) - #153161 (Rejig `rustc_with_all_queries!`) - #153191 ( don't emit `unused_results` lint for tuples of "trivial" types ) - #153273 (vec/mod.rs: add missing period in "ie." in docs) - #153292 (tests: codegen-llvm: vec-calloc: do not require the uwtable attribute) - #153293 (library: std: process: skip tests on Hermit) - #153301 (Do not ping kobzol on rustc-dev-guide changes)

…uwer Rollup of 10 pull requests Successful merges: - #153153 (add tests for thumb interworking) - #151780 (Updated slice tests to pass for big endian hosts for `multiple-option-or-permutations.rs`) - #151962 (Fix next-solver ICE on PointeeSized goals) - #153015 (core: make atomic primitives type aliases of `Atomic<T>`) - #153161 (Rejig `rustc_with_all_queries!`) - #153191 ( don't emit `unused_results` lint for tuples of "trivial" types ) - #153273 (vec/mod.rs: add missing period in "ie." in docs) - #153292 (tests: codegen-llvm: vec-calloc: do not require the uwtable attribute) - #153293 (library: std: process: skip tests on Hermit) - #153301 (Do not ping kobzol on rustc-dev-guide changes)

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rustbot added the has-merge-commits PR has merge commits, merge with caution. label Feb 8, 2026

rwardd and others added 2 commits February 8, 2026 15:34

fix: updated slice tests to pass for big endian hosts

0bf2d00

fix: refactored to use directives instead of CHECK-DAG

5265ee0

rwardd force-pushed the ryan/fix-option-permutations branch from 61d5d8e to 5265ee0 Compare February 8, 2026 05:06

rustbot added A-compiletest Area: The compiletest test runner A-testsuite Area: The testsuite used to check the correctness of rustc T-bootstrap Relevant to the bootstrap subteam: Rust's build system (x.py and src/bootstrap) labels Feb 8, 2026

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nikic mentioned this pull request Mar 2, 2026

Select of lshr not converted to lshr of select with one multi-use operand llvm/llvm-project#184131

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Rollup of 5 pull requests #153296

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Rollup of 9 pull requests #153299

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Rollup of 11 pull requests #153303

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Rollup of 10 pull requests #153304

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rust-bors bot merged commit 1654b17 into rust-lang:main Mar 2, 2026
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rustbot added this to the 1.96.0 milestone Mar 2, 2026

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