Fix emscripten_yield to avoid calling timers from Wasm Workers#26750
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Apr 22, 2026
Timers are only ever run on them main runtime thread. In emscripten-core#26655 I added an assertion to ensure that `_emscripten_check_timers` is only called from the main runtime thread. This broke tests such as `lto0.test_wasm_worker_futex_wait`. The reason this test only failed in the LTO build on not under core0 is due to a bug in LTO which defeats the weak alias mechanism that is designed to only pull in the timer code when needed: ``` weak_alias(dummy, _emscripten_check_timers); ``` This changes fixes the stub version of `emscripten_yield_stub` so that it avoids calling `_emscripten_check_timers` from Wasm Workers. Note: In a Wasm Workers build one can register and use timers from the main thread, but one cannot register a timer from a Wasm Worker (because _setitimer_js is a proxied func).
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Timers are only ever run on them main runtime thread. In #26655 I added an assertion to ensure that
_emscripten_check_timersis only called from the main runtime thread. This broke tests such aslto0.test_wasm_worker_futex_wait.The reason this test only failed in the LTO build on not under core0 is due to a bug in LTO which defeats the weak alias mechanism that is designed to only pull in the timer code when needed:
This changes fixes the stub version of
emscripten_yield_stubso that it avoids calling_emscripten_check_timersfrom Wasm Workers.Note: In a Wasm Workers build one can register and use timers from the main thread, but one cannot register a timer from a Wasm Worker (because _setitimer_js is a proxied func).
Fixes: #26749