Revert "Fix linking statics on Arm64EC #140176" #141024
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Unfortunately, multiple people are reporting linker warnings related to `__rust_no_alloc_shim_is_unstable` after this change. The solution isn't quite clear yet, let's revert to green for now, and try a reland with a determined solution for `__rust_no_alloc_shim_is_unstable`. This reverts commit c8b7f32, reversing changes made to 667247d.
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Nominating this for beta backport because people are reporting seeing the linker warning in bootstrapping as well. However, the beta backport is a "pick your poison" situation, where we avoid the linker warnings in Tier 1 @rustbot label: +beta-nominated |
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What is this?This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.Comparing a69bc17 (parent) -> b0e9259 (this PR) Test differencesShow 3 test diffsStage 1
Stage 2
Job group index
Test dashboardRun cargo run --manifest-path src/ci/citool/Cargo.toml -- \
test-dashboard b0e925903a04fc3b2e0903ce6110938e871c61a1 --output-dir test-dashboardAnd then open Job duration changes
How to interpret the job duration changes?Job durations can vary a lot, based on the actual runner instance |
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Finished benchmarking commit (b0e9259): comparison URL. Overall result: no relevant changes - no action needed@rustbot label: -perf-regression Instruction countThis benchmark run did not return any relevant results for this metric. Max RSS (memory usage)Results (primary -1.6%, secondary -2.0%)This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.
CyclesResults (secondary -0.0%)This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.
Binary sizeThis benchmark run did not return any relevant results for this metric. Bootstrap: 774.345s -> 775.66s (0.17%) |
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[beta] backports and stage0 bump - bump stage0 - Update the edition guide for let chains rust-lang#140852 - Fix download of GCC from CI on non-nightly channels rust-lang#140901 - Revert "Fix linking statics on Arm64EC rust-lang#140176" rust-lang#141024 - [win][arm64] Remove 'Arm64 Hazard' undocumented MSVC option and instead disable problematic test rust-lang#141045 - Do not call name() on rpitit assoc_item rust-lang#141308 r? cuviper
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[beta] backports and stage0 bump - bump stage0 to 1.87.0 - Update the edition guide for let chains #140852 - Fix download of GCC from CI on non-nightly channels #140901 - Revert "Fix linking statics on Arm64EC #140176" #141024 - [win][arm64] Remove 'Arm64 Hazard' undocumented MSVC option and instead disable problematic test #141045 - Do not call name() on rpitit assoc_item #141308 - Temporarily use Windows Server 2022 instead of Windows Server 2025 images #141023 r? cuviper
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[beta] backports and stage0 bump - bump stage0 to 1.87.0 - Update the edition guide for let chains #140852 - Fix download of GCC from CI on non-nightly channels #140901 - Revert "Fix linking statics on Arm64EC #140176" #141024 - [win][arm64] Remove 'Arm64 Hazard' undocumented MSVC option and instead disable problematic test #141045 - Do not call name() on rpitit assoc_item #141308 - Temporarily use Windows Server 2022 instead of Windows Server 2025 images #141023 - Use Docker cache from the current repository #141280 - Move dist-x86_64-linux CI job to GitHub temporarily #141388 - ci: prepare aws access keys for migration #141389 r? cuviper
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[beta] backports and stage0 bump - bump stage0 to 1.87.0 - Update the edition guide for let chains #140852 - Fix download of GCC from CI on non-nightly channels #140901 - Revert "Fix linking statics on Arm64EC #140176" #141024 - [win][arm64] Remove 'Arm64 Hazard' undocumented MSVC option and instead disable problematic test #141045 - Do not call name() on rpitit assoc_item #141308 - Temporarily use Windows Server 2022 instead of Windows Server 2025 images #141023 - Use Docker cache from the current repository #141280 - Move dist-x86_64-linux CI job to GitHub temporarily #141388 - ci: prepare aws access keys for migration #141389 - Add bors environment to CI #141323 r? cuviper
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[beta] backports and stage0 bump - bump stage0 to 1.87.0 - Update the edition guide for let chains #140852 - Fix download of GCC from CI on non-nightly channels #140901 - Revert "Fix linking statics on Arm64EC #140176" #141024 - [win][arm64] Remove 'Arm64 Hazard' undocumented MSVC option and instead disable problematic test #141045 - Do not call name() on rpitit assoc_item #141308 - Temporarily use Windows Server 2022 instead of Windows Server 2025 images #141023 - Use Docker cache from the current repository #141280 - Move dist-x86_64-linux CI job to GitHub temporarily #141388 - ci: prepare aws access keys for migration #141389 - Add bors environment to CI #141323 - ci: split dist-arm-linux job #141078 r? cuviper
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To include beta backport of revert rust-lang#141024 which should undo linker warnings during bootstrapping of Windows MSVC targets due to rust-lang#140176.
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To include beta backport of revert <rust-lang#141024> which should undo linker warnings during bootstrapping of Windows MSVC targets due to <rust-lang#140176>.
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…troalbini Bump master `stage0` compiler To include beta backport of revert rust-lang#141024 which should undo linker warnings during bootstrapping of Windows MSVC targets due to rust-lang#140176. Closes rust-lang#141395. r? `@Mark-Simulacrum` (or release)
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Bump master `stage0` compiler To include beta backport of revert rust-lang/rust#141024 which should undo linker warnings during bootstrapping of Windows MSVC targets due to rust-lang/rust#140176. Closes rust-lang/rust#141395. r? `@Mark-Simulacrum` (or release)
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Change __rust_no_alloc_shim_is_unstable to be a function This fixes a long sequence of issues: 1. A customer reported that building for Arm64EC was broken: rust-lang#138541 2. This was caused by a bug in my original implementation of Arm64EC support, namely that only functions on Arm64EC need to be decorated with `#` but Rust was decorating statics as well. 3. Once I corrected Rust to only decorate functions, I started linking failures where the linker couldn't find statics exported by dylib dependencies. This was caused by the compiler not marking exported statics in the generated DEF file with `DATA`, thus they were being exported as functions not data. 4. Once I corrected the way that the DEF files were being emitted, the linker started failing saying that it couldn't find `__rust_no_alloc_shim_is_unstable`. This is because the MSVC linker requires the declarations of statics imported from other dylibs to be marked with `dllimport` (whereas it will happily link to functions imported from other dylibs whether they are marked `dllimport` or not). 5. I then made a change to ensure that `__rust_no_alloc_shim_is_unstable` was marked as `dllimport`, but the MSVC linker started emitting warnings that `__rust_no_alloc_shim_is_unstable` was marked as `dllimport` but was declared in an obj file. This is a harmless warning which is a performance hint: anything that's marked `dllimport` must be indirected via an `__imp` symbol so I added a linker arg in the target to suppress the warning. 6. A customer then reported a similar warning when using `lld-link` (<rust-lang#140176 (comment)>). I don't think it was an implementation difference between the two linkers but rather that, depending on the obj that the declaration versus uses of `__rust_no_alloc_shim_is_unstable` landed in we would get different warnings, so I suppressed that warning as well: rust-lang#140954. 7. Another customer reported that they weren't using the Rust compiler to invoke the linker, thus these warnings were breaking their build: <rust-lang#140176 (comment)>. At that point, my original change was reverted (rust-lang#141024) leaving Arm64EC broken yet again. Taking a step back, a lot of these linker issues arise from the fact that `__rust_no_alloc_shim_is_unstable` is marked as `extern "Rust"` in the standard library and, therefore, assumed to be a foreign item from a different crate BUT the Rust compiler may choose to generate it either in the current crate, some other crate that will be statically linked in OR some other crate that will by dynamically imported. Worse yet, it is impossible while building a given crate to know if `__rust_no_alloc_shim_is_unstable` will statically linked or dynamically imported: it might be that one of its dependent crates is the one with an allocator kind set and thus that crate (which is compiled later) will decide depending if it has any dylib dependencies or not to import `__rust_no_alloc_shim_is_unstable` or generate it. Thus, there is no way to know if the declaration of `__rust_no_alloc_shim_is_unstable` should be marked with `dllimport` or not. There is a simple fix for all this: there is no reason `__rust_no_alloc_shim_is_unstable` must be a static. It needs to be some symbol that must be linked in; thus, it could easily be a function instead. As a function, there is no need to mark it as `dllimport` when dynamically imported which avoids the entire mess above. There may be a perf hit for changing the `volatile load` to be a `tail call`, so I'm happy to change that part back (although I question what the codegen of a `volatile load` would look like, and if the backend is going to try to use load-acquire semantics). Build with this change applied BEFORE rust-lang#140176 was reverted to demonstrate that there are no linking issues with either MSVC or MinGW: <https://github.com/rust-lang/rust/actions/runs/15078657205> Incidentally, I fixed `tests/run-make/no-alloc-shim` to work with MSVC as I needed it to be able to test locally (FYI for rust-lang#128602) r? `@bjorn3` cc `@jieyouxu`
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Change __rust_no_alloc_shim_is_unstable to be a function This fixes a long sequence of issues: 1. A customer reported that building for Arm64EC was broken: rust-lang#138541 2. This was caused by a bug in my original implementation of Arm64EC support, namely that only functions on Arm64EC need to be decorated with `#` but Rust was decorating statics as well. 3. Once I corrected Rust to only decorate functions, I started linking failures where the linker couldn't find statics exported by dylib dependencies. This was caused by the compiler not marking exported statics in the generated DEF file with `DATA`, thus they were being exported as functions not data. 4. Once I corrected the way that the DEF files were being emitted, the linker started failing saying that it couldn't find `__rust_no_alloc_shim_is_unstable`. This is because the MSVC linker requires the declarations of statics imported from other dylibs to be marked with `dllimport` (whereas it will happily link to functions imported from other dylibs whether they are marked `dllimport` or not). 5. I then made a change to ensure that `__rust_no_alloc_shim_is_unstable` was marked as `dllimport`, but the MSVC linker started emitting warnings that `__rust_no_alloc_shim_is_unstable` was marked as `dllimport` but was declared in an obj file. This is a harmless warning which is a performance hint: anything that's marked `dllimport` must be indirected via an `__imp` symbol so I added a linker arg in the target to suppress the warning. 6. A customer then reported a similar warning when using `lld-link` (<rust-lang#140176 (comment)>). I don't think it was an implementation difference between the two linkers but rather that, depending on the obj that the declaration versus uses of `__rust_no_alloc_shim_is_unstable` landed in we would get different warnings, so I suppressed that warning as well: rust-lang#140954. 7. Another customer reported that they weren't using the Rust compiler to invoke the linker, thus these warnings were breaking their build: <rust-lang#140176 (comment)>. At that point, my original change was reverted (rust-lang#141024) leaving Arm64EC broken yet again. Taking a step back, a lot of these linker issues arise from the fact that `__rust_no_alloc_shim_is_unstable` is marked as `extern "Rust"` in the standard library and, therefore, assumed to be a foreign item from a different crate BUT the Rust compiler may choose to generate it either in the current crate, some other crate that will be statically linked in OR some other crate that will by dynamically imported. Worse yet, it is impossible while building a given crate to know if `__rust_no_alloc_shim_is_unstable` will statically linked or dynamically imported: it might be that one of its dependent crates is the one with an allocator kind set and thus that crate (which is compiled later) will decide depending if it has any dylib dependencies or not to import `__rust_no_alloc_shim_is_unstable` or generate it. Thus, there is no way to know if the declaration of `__rust_no_alloc_shim_is_unstable` should be marked with `dllimport` or not. There is a simple fix for all this: there is no reason `__rust_no_alloc_shim_is_unstable` must be a static. It needs to be some symbol that must be linked in; thus, it could easily be a function instead. As a function, there is no need to mark it as `dllimport` when dynamically imported which avoids the entire mess above. There may be a perf hit for changing the `volatile load` to be a `tail call`, so I'm happy to change that part back (although I question what the codegen of a `volatile load` would look like, and if the backend is going to try to use load-acquire semantics). Build with this change applied BEFORE rust-lang#140176 was reverted to demonstrate that there are no linking issues with either MSVC or MinGW: <https://github.com/rust-lang/rust/actions/runs/15078657205> Incidentally, I fixed `tests/run-make/no-alloc-shim` to work with MSVC as I needed it to be able to test locally (FYI for rust-lang#128602) r? `@bjorn3` cc `@jieyouxu`
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Change __rust_no_alloc_shim_is_unstable to be a function This fixes a long sequence of issues: 1. A customer reported that building for Arm64EC was broken: rust-lang#138541 2. This was caused by a bug in my original implementation of Arm64EC support, namely that only functions on Arm64EC need to be decorated with `#` but Rust was decorating statics as well. 3. Once I corrected Rust to only decorate functions, I started linking failures where the linker couldn't find statics exported by dylib dependencies. This was caused by the compiler not marking exported statics in the generated DEF file with `DATA`, thus they were being exported as functions not data. 4. Once I corrected the way that the DEF files were being emitted, the linker started failing saying that it couldn't find `__rust_no_alloc_shim_is_unstable`. This is because the MSVC linker requires the declarations of statics imported from other dylibs to be marked with `dllimport` (whereas it will happily link to functions imported from other dylibs whether they are marked `dllimport` or not). 5. I then made a change to ensure that `__rust_no_alloc_shim_is_unstable` was marked as `dllimport`, but the MSVC linker started emitting warnings that `__rust_no_alloc_shim_is_unstable` was marked as `dllimport` but was declared in an obj file. This is a harmless warning which is a performance hint: anything that's marked `dllimport` must be indirected via an `__imp` symbol so I added a linker arg in the target to suppress the warning. 6. A customer then reported a similar warning when using `lld-link` (<rust-lang#140176 (comment)>). I don't think it was an implementation difference between the two linkers but rather that, depending on the obj that the declaration versus uses of `__rust_no_alloc_shim_is_unstable` landed in we would get different warnings, so I suppressed that warning as well: rust-lang#140954. 7. Another customer reported that they weren't using the Rust compiler to invoke the linker, thus these warnings were breaking their build: <rust-lang#140176 (comment)>. At that point, my original change was reverted (rust-lang#141024) leaving Arm64EC broken yet again. Taking a step back, a lot of these linker issues arise from the fact that `__rust_no_alloc_shim_is_unstable` is marked as `extern "Rust"` in the standard library and, therefore, assumed to be a foreign item from a different crate BUT the Rust compiler may choose to generate it either in the current crate, some other crate that will be statically linked in OR some other crate that will by dynamically imported. Worse yet, it is impossible while building a given crate to know if `__rust_no_alloc_shim_is_unstable` will statically linked or dynamically imported: it might be that one of its dependent crates is the one with an allocator kind set and thus that crate (which is compiled later) will decide depending if it has any dylib dependencies or not to import `__rust_no_alloc_shim_is_unstable` or generate it. Thus, there is no way to know if the declaration of `__rust_no_alloc_shim_is_unstable` should be marked with `dllimport` or not. There is a simple fix for all this: there is no reason `__rust_no_alloc_shim_is_unstable` must be a static. It needs to be some symbol that must be linked in; thus, it could easily be a function instead. As a function, there is no need to mark it as `dllimport` when dynamically imported which avoids the entire mess above. There may be a perf hit for changing the `volatile load` to be a `tail call`, so I'm happy to change that part back (although I question what the codegen of a `volatile load` would look like, and if the backend is going to try to use load-acquire semantics). Build with this change applied BEFORE rust-lang#140176 was reverted to demonstrate that there are no linking issues with either MSVC or MinGW: <https://github.com/rust-lang/rust/actions/runs/15078657205> Incidentally, I fixed `tests/run-make/no-alloc-shim` to work with MSVC as I needed it to be able to test locally (FYI for rust-lang#128602) r? ``@bjorn3`` cc ``@jieyouxu``
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This reverts PR #140176.
Unfortunately, this will reopen #138541 (re-breaking the
arm64ec-pc-windows-msvctarget).Unfortunately, multiple people are reporting linker warnings related to
__rust_no_alloc_shim_is_unstableafter this change inx86_64-pc-windows-msvcas well. The solution isn't quite clear yet, let's revert to avoid the linker warnings on the Tier 1 MSVC target for now1, and try a reland with a determined solution for__rust_no_alloc_shim_is_unstable.Judging from people reporting that they are observing this also when bootstrapping w/ stage0 rustc, we may have to cut a new beta and then repoint stage0 against that newer beta?
cc @dpaoliello @wesleywiser
r? @wesleywiser (or compiler)
Footnotes
Note that it's still RustWeek this week, so most team members are N/A. ↩