Missing 64-bit AtomicCmpxchg causes `__sync_fetch_and_nand` to fail under wasm2js

Open
#4,358 2 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Bug
Clarity
Needs clarification
Activity status
Stale
Tech stack
cpp, wasm
Domain
compilers

Research direction

Start in I64ToI32Lowering.cpp at visitAtomicCmpxchg and reproduce the __sync_fetch_and_nand case with 64-bit operands under emscripten and wasm2js. The issue is resolved when this usage no longer triggers the reported assertion; no specific test file is named, so inspect the existing test code referenced by the issue.

Written by the indexing model from the issue text.

Description

Usage of __sync_fetch_and_nand with 64-bit operands in emscripten causes the following error:

wasm2js: /usr/local/google/home/sbc/dev/wasm/binaryen/src/passes/I64ToI32Lowering.cpp:471: void wasm::I64ToI32Lowering::visitAtomicCmpxchg(wasm::AtomicCmpxchg *): Assertion `curr->type != Type::i64 && "64-bit AtomicCmpxchg not implemented"' failed.

I think this is probably super rare and not a huge deal, but creating this issue so I can link to it in the test code.

Dominant language
WebAssembly
Stars
8.6k
Forks
885
Avg merge
2d 1h
Merged PRs (30d)
70

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.

More from WebAssembly/binaryen

All issues in WebAssembly/binaryen

Similar issues

More Compilers issues

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.