f128 on wasm does not support maximum intrinsic #158673

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1. ChrisDenton

   added

   T-compilerRelevant to the compiler team, which will review and decide on the PR/issue.Relevant to the compiler team, which will review and decide on the PR/issue.

   F-f16_and_f128`#![feature(f16)]`, `#![feature(f128)]``#![feature(f16)]`, `#![feature(f128)]`

   on Jul 1, 2026
2. rustbot

   added

   needs-triageThis issue may need triage. Remove when done. See docs forge.rust-lang.org/release/issue-triagingThis issue may need triage. Remove when done. See docs forge.rust-lang.org/release/issue-triaging

   on Jul 1, 2026
3. tgross35 commented on Jul 1, 2026

   

   tgross35

   on Jul 1, 2026

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   Easy repro with --target wasm32-unknown-unknown https://rust.godbolt.org/z/Mxnhnxqoq:

   #![feature(f128)]
   
   #[unsafe(no_mangle)]
   pub fn f128_max(a: f128, b: f128) -> f128 {
       a.max(b)
   }

   We actually don't need a quick fix on the Rust side for that PR, just a gate update. This would build but not run correctly on almost all platforms anyway because of llvm/llvm-project#44744.
4. tgross35

   added

   A-LLVMArea: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues.Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues.

   WG-llvmWorking group: LLVM backend code generationWorking group: LLVM backend code generation

   and removed

   needs-triageThis issue may need triage. Remove when done. See docs forge.rust-lang.org/release/issue-triagingThis issue may need triage. Remove when done. See docs forge.rust-lang.org/release/issue-triaging

   on Jul 1, 2026
5. tgross35 commented on Jul 1, 2026

   

   tgross35

   on Jul 1, 2026

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   llvm/llvm-project#207100
6. folkertdev

   added

   llvm-fixed-upstreamIssue expected to be fixed by the next major LLVM upgrade, or backported fixesIssue expected to be fixed by the next major LLVM upgrade, or backported fixes

   on Jul 8, 2026
7. folkertdev commented on Aug 5, 2026

   

   folkertdev

   on Aug 5, 2026

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   LLVM 23 does support these intrinsics for f128, is there anything left to do here?
8. tgross35 commented on Aug 5, 2026

   

   tgross35

   on Aug 5, 2026

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   Let's just wait until the godbolt link works (picks up the nightly releasing soon with LLVM23) then I think it's fine to close
9. tgross35 commented on Aug 6, 2026

   

   tgross35

   on Aug 6, 2026

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   The above link is now indeed fixed
10. tgross35

    closed this as completedon Aug 6, 2026