rust-lang / rust-lang/rust

Tracking Issue for wasm exception-handling architecture intrinsics

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C-tracking-issue T-libs
Dominant language
Rust
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Description

Feature gate: #![feature(wasm_exception_handling_intrinsics)]

This is a tracking issue for wasm exception-handling architecture intrinsics; currently, only the throw instruction is implemented as a platform intrinsic.

Public API
// core::arch::wasm32

pub unsafe fn throw<const TAG: i32>(ptr: *mut u8) -> !;
Steps / History
  • Implementation: rust-lang/stdarch#1542
  • Final comment period (FCP)^1
  • Stabilization PR
Unresolved Questions
  • Needs better support from LLVM before merging. At the moment, LLVM only accepts a tag value of 0, signifying a C++ exception. Ideally one would be able to somehow declare a tag in a similar way to a static, and pass that as the TAG to the intrinsic.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the wasm_exception_handling_intrinsics feature gate and the core::arch::wasm32::throw API, then review the implementation linked as rust-lang/stdarch#1542. Investigate the stated LLVM limitation around nonzero exception tags; completion would require resolving that support and progressing the listed FCP and stabilization steps.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust, wasm
Domain
compilers
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
25/100

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