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[wasi][R2R] BFloat16 conversions from Int128/UInt128 produce wrong values #135116
Description
Description
In the CoreCLR WASI composite ReadyToRun library lane (LibraryTestsCoreCLR_WASI_R2R, trimmed), BFloat16 explicit conversions from Int128/UInt128 produce wrong values. The same tests pass in the WASI interpreter lane, so the R2R (RyuJIT wasm) code is wrong.
[FAIL] System.Numerics.Tests.BFloat16Tests.ExplicitConversion_FromInt128(i: 16563852592415126800007719339717296127, expected: 2.99E-26)
Expected: 2.9888E-26
Actual: 1.6532E+37
[FAIL] System.Numerics.Tests.BFloat16Tests.ExplicitConversion_FromInt128(i: 336347874021343232, expected: 0)
Expected: +0.0
Actual: 3.3552E+17
[FAIL] System.Numerics.Tests.BFloat16Tests.ExplicitConversion_FromUInt128(...)
Reproduces locally (macOS arm64 host, wasmtime 49.0.1): System.Runtime.Tests built with /p:TestWasmReadyToRun=true /p:EnableAggressiveTrimming=true, class filter System.Numerics.Tests.BFloat16Tests: 1608 run, 3 failed.
Seen in Helix job eccd7d69-de48-4cc1-87fd-6036eb264d50 (#134813) and earlier runs. Quarantined on WASI R2R in #134813.
Note
This issue was drafted with GitHub Copilot.
Activity
dotnet-policy-service commentedon Oct 2, 2026
Tagging subscribers to 'arch-wasm': @lewing, @pavelsavara
See info in area-owners.md if you want to be subscribed.
dotnet-policy-service commentedon Oct 2, 2026
Tagging subscribers to this area: @dotnet/area-system-numerics
See info in area-owners.md if you want to be subscribed.
[wasi] Quarantine remaining WASI ReadyToRun library failures
[wasi] Quarantine remaining WASI ReadyToRun library failures
lewing commentedon Oct 6, 2026
cc @tannergooding @adamperlin
Re-enable BFloat16 Int128/UInt128 conversion tests on WASI ReadyToRun (…