Panic in LLVM when using #[linkage] even with supported targets #33992

mattico · 2016-05-31T21:02:10Z

λ cargo new test-linkage
λ cd test-linkage
λ cat src/lib.rs
#![feature(linkage)]

#[linkage = "extern_weak"]
pub static TEST: bool = false;

λ env RUST_BACKTRACE=1 cargo build --verbose # OR
λ env RUST_BACKTRACE=1 cargo build --verbose --target x86_64-unknown-linux-gnu
   Compiling test-linkage v0.1.0 (file:///C:/Users/Matt%20Ickstadt/Code/Rust/test-linkage)
     Running `rustc src\lib.rs --crate-name test_linkage --crate-type lib -g --out-dir "C:\Users\Matt Ickstadt\Code\Rust\test-linkage\target\x86_64-unknown-linux-gnu\debug" --emit=dep-info,link --target x86_64-unknown-linux-gnu -L "dependency=C:\Users\Matt Ickstadt\Code\Rust\test-linkage\target\x86_64-unknown-linux-gnu\debug" -L "dependency=C:\Users\Matt Ickstadt\Code\Rust\test-linkage\target\x86_64-unknown-linux-gnu\debug\deps"`
Don't know how to emit these
UNREACHABLE executed at C:/bot/slave/nightly-dist-rustc-win-gnu-32/build/src/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp:336!

This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.
error: Could not compile `test-linkage`.

Caused by:
  Process didn't exit successfully: `rustc src\lib.rs --crate-name test_linkage --crate-type lib -g --out-dir C:\Users\Matt Ickstadt\Code\Rust\test-linkage\target\x86_64-unknown-linux-gnu\debug --emit=dep-info,link --target x86_64-unknown-linux-gnu -L dependency=C:\Users\Matt Ickstadt\Code\Rust\test-linkage\target\x86_64-unknown-linux-gnu\debug -L dependency=C:\Users\Matt Ickstadt\Code\Rust\test-linkage\target\x86_64-unknown-linux-gnu\debug\deps` (exit code: 3)

Nothing too unexpected, since most targets don't support weak linkage. The error message could be a bit better though, rather than panicing in LLVM.

I was a bit surprised that this problem persists when cross compiling to supported targets, but I suppose that its an LLVM limitation, and a very niche one at that.

cc #29603

The text was updated successfully, but these errors were encountered:

mattico · 2016-05-31T21:17:49Z

Just ran this on Ubuntu, expecting it to work, and it didn't. I guess this isn't Windows issue after all.

Am I using this attribute incorrectly? Does it work?

mattico · 2016-05-31T21:27:57Z

Well it works with #[linkage = "weak"] so I'm starting to think that LLVM changed/removed "extern_weak".

mattico · 2016-05-31T21:40:44Z

If I'm reading https://github.com/rust-lang/llvm/blob/master/include/llvm/IR/GlobalValue.h#L32 correctly, ExternalWeakLinkage should equal 14 and CommonLinkage should equal 15. https://github.com/rust-lang/rust/blob/master/src/librustc_llvm/lib.rs#L102

mattico · 2016-05-31T22:14:08Z

I'm putting together a PR with the fix and some compile-pass tests. Might take a few hours to compile, though 😢

The `Linkage` enum in librustc_llvm got out of sync with the version in LLVM and it caused two variants of the #[linkage=""] attribute to break. Fixes rust-lang#33992

The `Linkage` enum in librustc_llvm got out of sync with the version in LLVM and it caused two variants of the #[linkage=""] attribute to break. This adds the functions `LLVMRustGetLinkage` and `LLVMRustSetLinkage` which convert between the Rust Linkage enum and the LLVM one, which should stop this from breaking every time LLVM changes it. Fixes rust-lang#33992

@alexcrichton

…chton Fix incorrect LLVM Linkage enum Followup of rust-lang#33994 to actually work. The `Linkage` enum in librustc_llvm got out of sync with the version in LLVM and it caused two variants of the `#[linkage=""]` attribute to break. This adds the functions `LLVMRustGetLinkage` and `LLVMRustSetLinkage` which convert between the Rust Linkage enum and the LLVM one, which should stop this from breaking every time LLVM changes it. Possible remaining concerns: 1. There could be a codegen test to make sure that the attributes are applied correctly (I don't know how to do this). 2. The test does not exercise the `appending` linkage. I can't figure out how to make a global static raw pointer to an array. This might not even be possible? If not we should probably remove appending linkage as its unusable in rust. 3. The test only runs on Linux. Fixes rust-lang#33992 r? @alexcrichton

TimNN · 2016-09-04T08:11:24Z

Edit: This was meant to be posted to the corresponding pull request.

---- [run-pass] run-pass/issue-33992.rs stdout ----

error: compilation failed!
status: signal: 6
command: /buildslave/rust-buildbot/slave/auto-linux-64-opt-rustbuild/build/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc /buildslave/rust-buildbot/slave/auto-linux-64-opt-rustbuild/build/src/test/run-pass/issue-33992.rs -L /buildslave/rust-buildbot/slave/auto-linux-64-opt-rustbuild/build/obj/build/x86_64-unknown-linux-gnu/test/run-pass --target=x86_64-unknown-linux-gnu --error-format json -L /buildslave/rust-buildbot/slave/auto-linux-64-opt-rustbuild/build/obj/build/x86_64-unknown-linux-gnu/test/run-pass/issue-33992.stage2-x86_64-unknown-linux-gnu.run-pass.libaux -C prefer-dynamic -o /buildslave/rust-buildbot/slave/auto-linux-64-opt-rustbuild/build/obj/build/x86_64-unknown-linux-gnu/test/run-pass/issue-33992.stage2-x86_64-unknown-linux-gnu -Crpath -O -Lnative=/buildslave/rust-buildbot/slave/auto-linux-64-opt-rustbuild/build/obj/build/x86_64-unknown-linux-gnu/rust-test-helpers
stdout:
------------------------------------------

------------------------------------------
stderr:
------------------------------------------
Should never emit this
UNREACHABLE executed at /buildslave/rust-buildbot/slave/auto-linux-64-opt-rustbuild/build/src/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp:336!

------------------------------------------

The `Linkage` enum in librustc_llvm got out of sync with the version in LLVM and it caused two variants of the #[linkage=""] attribute to break. This adds the functions `LLVMRustGetLinkage` and `LLVMRustSetLinkage` which convert between the Rust Linkage enum and the LLVM one, which should stop this from breaking every time LLVM changes it. Fixes rust-lang#33992

@alexcrichton

Fix incorrect LLVM Linkage enum Followup of #33994 to actually work. The `Linkage` enum in librustc_llvm got out of sync with the version in LLVM and it caused two variants of the `#[linkage=""]` attribute to break. This adds the functions `LLVMRustGetLinkage` and `LLVMRustSetLinkage` which convert between the Rust Linkage enum and the LLVM one, which should stop this from breaking every time LLVM changes it. Possible remaining concerns: 1. There could be a codegen test to make sure that the attributes are applied correctly (I don't know how to do this). 2. ~~The test does not exercise the `appending` linkage. I can't figure out how to make a global static raw pointer to an array. This might not even be possible? If not we should probably remove appending linkage as its unusable in rust.~~ Appending linkage is not 'emittable' anyway. 3. The test only runs on Linux. Fixes #33992 r? @alexcrichton

mattico changed the title ~~Panic in LLVM when using #[linkage] on Windows, even with supported targets~~ Panic in LLVM when using #[linkage] even with supported targets May 31, 2016

mattico mentioned this issue May 31, 2016

[WIP] Fix incorrect LLVM Linkage enum #33994

Closed

mattico added a commit to mattico/rust that referenced this issue Jun 1, 2016

Fix incorrect LLVM Linkage enum

3e0f018

The `Linkage` enum in librustc_llvm got out of sync with the version in LLVM and it caused two variants of the #[linkage=""] attribute to break. Fixes rust-lang#33992

retep998 mentioned this issue Aug 8, 2016

Port compiler-rt intrinsics to Rust #35437

Closed

mattico mentioned this issue Sep 1, 2016

Fix incorrect LLVM Linkage enum #36200

Merged

bors closed this as completed in #36200 Sep 5, 2016

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Panic in LLVM when using #[linkage] even with supported targets #33992

Panic in LLVM when using #[linkage] even with supported targets #33992

mattico commented May 31, 2016

mattico commented May 31, 2016

mattico commented May 31, 2016

mattico commented May 31, 2016

mattico commented May 31, 2016

TimNN commented Sep 4, 2016 •

edited

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Panic in LLVM when using #[linkage] even with supported targets #33992

Panic in LLVM when using #[linkage] even with supported targets #33992

Comments

mattico commented May 31, 2016

mattico commented May 31, 2016

mattico commented May 31, 2016

mattico commented May 31, 2016

mattico commented May 31, 2016

TimNN commented Sep 4, 2016 • edited Loading

TimNN commented Sep 4, 2016 •

edited

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