This fixes a WebAssembly SIMD miscompilation caused by a typo that left the B3 Procedure’s ‘uses SIMD’ flag unset. B3 must know when a compilation uses SIMD so it configures vector register handling and related codegen correctly (setUsesSIMD sets m_usesSIMD and asserts Options::useWasmSIMD()). Two defects combined: the setter was misspelled setUsessSIMD() (double ’s’), and the WASM OMG IR generator’s notifyFunctionUsesSIMD() — invoked when a WASM function is known to use SIMD — was an empty body that only ASSERTed m_info.usesSIMD(…) and NEVER propagated the fact to B3 (it did not call m_proc.setUsesSIMD()).

As a result, a WASM function that uses SIMD could be compiled with the Procedure’s m_usesSIMD flag still false, so B3/Air generate code without the SIMD-aware handling the vector operations require — a miscompilation that mishandles vector registers/values, corrupting state or crashing.

The fix renames the setter to setUsesSIMD(), makes notifyFunctionUsesSIMD() actually call m_proc.setUsesSIMD() (and adds a usesSIMD() query), so the flag is set whenever a function uses SIMD.

The restored invariant is that B3 is told a compilation uses SIMD before it generates code for SIMD operations.

A WebAssembly SIMD JIT miscompilation in the WebContent process, reachable from any page running SIMD WASM. Generating code without the SIMD flag mishandles vector registers/values, a memory-safety hazard the advisory rates as a crash that can underpin further corruption.