add tests for thumb interworking by folkertdev · Pull Request #153153 · rust-lang/rust

folkertdev · 2026-02-26T20:53:54Z

fixes #151946

thumb programs (using a 16-bit instruction encoding) can call arm (32-bit instruction encoding) code. Doing so requires switching from thumb mode to arm mode, executing, then switching back. Test that this happens correctly, in particular for naked functions.

cc @thejpster can you confirm the output looks good here and that we're testing all of the relevant things
r? jieyouxu because this is doing some interesting things testing-wise

I believe that we need run-make here because we need to look at the assembly after the linker has run. It will correct calls from thumb to arm: depending on the thumb version this either uses a special instruction or inserts a call to a thunk that handles switching between thumb and arm mode.

rustbot · 2026-02-26T20:53:57Z

The run-make-support library was changed

cc @jieyouxu

folkertdev · 2026-02-26T23:48:21Z

@theemathas why was this closed?

folkertdev · 2026-02-27T00:01:00Z

I'm assuming it was closed on accident then?

theemathas · 2026-02-27T00:55:56Z

I've never seen this PR before. Don't know what happened.

thejpster · 2026-02-27T07:25:23Z

I don’t know the details of the test infra so I can’t comment there. The examples look good but perhaps:

it could be renamed ‘thumb-interworking’ because that’s the target flag
The a32 and t32 files can be merged into one, with entry calling six functions
The test could be extended to all targets with thumb-interworking enabled?

I also wondered if the hash in the thunk name was stable or if we needed to Wildcard it?

tests/run-make/thumb-calling-arm/rmake.rs

jieyouxu · 2026-02-28T08:21:18Z

@rustbot author

rustbot · 2026-02-28T08:21:22Z

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

folkertdev

Good points @thejpster, I've renamed and added tests using the arm targets.

@rustbot ready

View changes since this review

tests/run-make/thumb-interworking/rmake.rs

thejpster · 2026-03-01T20:24:23Z

Looks good to me. You could also add:

armv6-none-eabi
armv6-none-eabihf
thumbv6-none-eabi
armv7r-none-eabi
armv7r-none-eabihf
thumbv7r-none-eabi
thumbv7r-none-eabihf
armv7a-none-eabi
armv7a-none-eabihf
thumbv7a-none-eabi
thumbv7a-none-eabihf
armv8r-none-eabihf
thumbv8r-none-eabihf

But I wouldn't block this PR on that - they can be added later.

and in particular for naked functions in that scenario

folkertdev · 2026-03-02T12:30:18Z

I think this is ready then

jieyouxu

Thanks
@bors r+ rollup=iffy

View changes since this review

rust-bors · 2026-03-02T13:36:42Z

📌 Commit 2d8ceee has been approved by jieyouxu

It is now in the queue for this repository.

@thejpster

add tests for thumb interworking fixes rust-lang#151946 thumb programs (using a 16-bit instruction encoding) can call arm (32-bit instruction encoding) code. Doing so requires switching from thumb mode to arm mode, executing, then switching back. Test that this happens correctly, in particular for naked functions. cc @thejpster can you confirm the output looks good here and that we're testing all of the relevant things r? jieyouxu because this is doing some interesting things testing-wise I believe that we need run-make here because we need to look at the assembly after the linker has run. It will correct calls from thumb to arm: depending on the thumb version this either uses a special instruction or inserts a call to a thunk that handles switching between thumb and arm mode.

…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)

@thejpster

add tests for thumb interworking fixes rust-lang#151946 thumb programs (using a 16-bit instruction encoding) can call arm (32-bit instruction encoding) code. Doing so requires switching from thumb mode to arm mode, executing, then switching back. Test that this happens correctly, in particular for naked functions. cc @thejpster can you confirm the output looks good here and that we're testing all of the relevant things r? jieyouxu because this is doing some interesting things testing-wise I believe that we need run-make here because we need to look at the assembly after the linker has run. It will correct calls from thumb to arm: depending on the thumb version this either uses a special instruction or inserts a call to a thunk that handles switching between thumb and arm mode.

…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)

rust-bors · 2026-03-02T18:44:07Z

⌛ Testing commit 2d8ceee with merge 059ecc1...

Workflow: https://github.com/rust-lang/rust/actions/runs/22590534046

@thejpster

add tests for thumb interworking fixes #151946 thumb programs (using a 16-bit instruction encoding) can call arm (32-bit instruction encoding) code. Doing so requires switching from thumb mode to arm mode, executing, then switching back. Test that this happens correctly, in particular for naked functions. cc @thejpster can you confirm the output looks good here and that we're testing all of the relevant things r? jieyouxu because this is doing some interesting things testing-wise I believe that we need run-make here because we need to look at the assembly after the linker has run. It will correct calls from thumb to arm: depending on the thumb version this either uses a special instruction or inserts a call to a thunk that handles switching between thumb and arm mode.

@thejpster

add tests for thumb interworking fixes rust-lang#151946 thumb programs (using a 16-bit instruction encoding) can call arm (32-bit instruction encoding) code. Doing so requires switching from thumb mode to arm mode, executing, then switching back. Test that this happens correctly, in particular for naked functions. cc @thejpster can you confirm the output looks good here and that we're testing all of the relevant things r? jieyouxu because this is doing some interesting things testing-wise I believe that we need run-make here because we need to look at the assembly after the linker has run. It will correct calls from thumb to arm: depending on the thumb version this either uses a special instruction or inserts a call to a thunk that handles switching between thumb and arm mode.

JonathanBrouwer · 2026-03-02T18:57:15Z

@bors yield
Yielding to enclosing rollup

rust-bors · 2026-03-02T18:57:18Z

Auto build cancelled. Cancelled workflows:

https://github.com/rust-lang/rust/actions/runs/22590534046

The next pull request likely to be tested is #153303.

…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)

rust-bors · 2026-03-02T19:09:32Z

⌛ Testing commit 2d8ceee with merge 3600963...

Workflow: https://github.com/rust-lang/rust/actions/runs/22591476163

@thejpster

add tests for thumb interworking fixes #151946 thumb programs (using a 16-bit instruction encoding) can call arm (32-bit instruction encoding) code. Doing so requires switching from thumb mode to arm mode, executing, then switching back. Test that this happens correctly, in particular for naked functions. cc @thejpster can you confirm the output looks good here and that we're testing all of the relevant things r? jieyouxu because this is doing some interesting things testing-wise I believe that we need run-make here because we need to look at the assembly after the linker has run. It will correct calls from thumb to arm: depending on the thumb version this either uses a special instruction or inserts a call to a thunk that handles switching between thumb and arm mode.

JonathanBrouwer · 2026-03-02T19:11:21Z

@bors yield
Yielding to enclosing rollup

rust-bors · 2026-03-02T19:11:25Z

Auto build cancelled. Cancelled workflows:

https://github.com/rust-lang/rust/actions/runs/22591476163

The next pull request likely to be tested is #153304.

…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)

rustbot added A-run-make Area: port run-make Makefiles to rmake.rs 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 Feb 26, 2026

rustbot assigned jieyouxu Feb 26, 2026

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folkertdev force-pushed the thumb-and-arm branch from b3d5462 to 1977b19 Compare February 26, 2026 21:56

theemathas closed this Feb 26, 2026

rustbot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Feb 26, 2026

folkertdev reopened this Feb 27, 2026

rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Feb 27, 2026

jieyouxu reviewed Feb 28, 2026

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folkertdev force-pushed the thumb-and-arm branch from 1977b19 to bbe9f23 Compare March 1, 2026 15:48

folkertdev commented Mar 1, 2026

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add tests for a thumb program calling arm code

2d8ceee

and in particular for naked functions in that scenario

folkertdev force-pushed the thumb-and-arm branch from bbe9f23 to 2d8ceee Compare March 2, 2026 09:54

folkertdev changed the title ~~add tests for thumb calling arm code~~ add tests for thumb interworking Mar 2, 2026

jieyouxu approved these changes Mar 2, 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 Mar 2, 2026

JonathanBrouwer mentioned this pull request Mar 2, 2026

Rollup of 5 pull requests #153296

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JonathanBrouwer mentioned this pull request Mar 2, 2026

Rollup of 9 pull requests #153299

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JonathanBrouwer mentioned this pull request Mar 2, 2026

Rollup of 11 pull requests #153303

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JonathanBrouwer mentioned this pull request Mar 2, 2026

Rollup of 10 pull requests #153304

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rust-bors bot merged commit 6d16e3b into rust-lang:main Mar 2, 2026
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