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Web Assembly Atomic fence support in atomic::fence #72997

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poliorcetics opened this issue Jun 4, 2020 · 0 comments · Fixed by #73036
Closed

Web Assembly Atomic fence support in atomic::fence #72997

poliorcetics opened this issue Jun 4, 2020 · 0 comments · Fixed by #73036
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C-bug Category: This is a bug. O-wasm Target: WASM (WebAssembly), http://webassembly.org/ T-libs Relevant to the library team, which will review and decide on the PR/issue.

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@poliorcetics
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The function pub fence(order: Ordering) in libcore/sync/atomic.rs does nothing when compiled for Web Assembly.

This stem from an old issue in web assembly #WebAssembly/tool-conventions/issues/59 and LLVM crashing (at the time) with it.

This has since been fixed, notably for LLVM, maybe we can remove the #[cfg(...)] and comment about it ?
@jonas-schievink jonas-schievink added T-libs Relevant to the library team, which will review and decide on the PR/issue. O-wasm Target: WASM (WebAssembly), http://webassembly.org/ labels Jun 4, 2020
@alexcrichton alexcrichton mentioned this issue Jun 5, 2020
Merged
@crlf0710 crlf0710 added the C-bug Category: This is a bug. label Jun 11, 2020
Dylan-DPC-zz pushed a commit to Dylan-DPC-zz/rust that referenced this issue Jun 11, 2020
@Dylan-DPC
Rollup merge of rust-lang#73036 - alexcrichton:update-wasm-fence, r=M…
3b41e54 
…ark-Simulacrum

std: Enable atomic.fence emission on wasm32

This commit removes the `#[cfg]` guards in `atomic::fence` on wasm
targets. Since these guards were originally added the upstream wasm
specification for threads gained an `atomic.fence` instruction, so LLVM
no longer panics on these intrinsics.

Although there aren't a ton of tests in-repo for this right now I've
tested locally and all of these fences generate `atomic.fence`
instructions in wasm.

Closes rust-lang#65687
Closes rust-lang#72997
@bors bors closed this as completed in 05b2d3f Jun 12, 2020
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C-bug Category: This is a bug. O-wasm Target: WASM (WebAssembly), http://webassembly.org/ T-libs Relevant to the library team, which will review and decide on the PR/issue.
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std: Enable atomic.fence emission on wasm32 alexcrichton/rust
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@crlf0710 @jonas-schievink @poliorcetics