wasmerio/wasmer · error

not yet implemented

Error message

not yet implemented

What it means

`get_simd_arch` on the RISC-V singlepass emitter is implemented as `todo!()`, meaning SIMD CPU-feature detection for RISC-V was never written. Any singlepass compilation path that queries the SIMD architecture on RISC-V panics with 'not yet implemented'. It indicates SIMD support is simply missing in the RISC-V backend.

Source

Thrown at lib/compiler-singlepass/src/emitter_riscv.rs:354

    fn emit_load_label(&mut self, reg: GPR, label: Label) -> Result<(), CompileError>;
    fn emit_call_label(&mut self, label: Label) -> Result<(), CompileError>;
    fn emit_call_register(&mut self, reg: GPR) -> Result<(), CompileError>;

    fn emit_rwfence(&mut self) -> Result<(), CompileError>;
    fn emit_atomic_binop(
        &mut self,
        op: AtomicBinaryOp,
        size: Size,
        dest: GPR,
        addr: GPR,
        source: GPR,
    ) -> Result<(), CompileError>;
    fn emit_reserved_ld(&mut self, size: Size, reg: GPR, addr: GPR) -> Result<(), CompileError>;
}

impl EmitterRiscv for Assembler {
    fn get_simd_arch(&self) -> Option<&CpuFeature> {
        todo!()
    }

    fn get_label(&mut self) -> Label {
        self.new_dynamic_label()
    }

    fn get_offset(&self) -> Offset {
        self.offset()
    }

    fn get_jmp_instr_size(&self) -> u8 {
        todo!()
    }

    fn finalize_function(&mut self) -> Result<(), CompileError> {
        Ok(())
    }

View on GitHub (pinned to 8c4b9ee9d3)

Solutions

1. Disable wasm SIMD: config.wasm_simd(false) before creating the engine
2. Use the Cranelift backend on RISC-V instead of singlepass
3. Upgrade wasmtime to a version where RISC-V SIMD support landed
4. Avoid v128-using modules on RISC-V singlepass

Example fix

// before: singlepass on riscv64 + wasm simd -> panic
let mut config = Config::new();
config.wasm_simd(true);
// after: disable simd on riscv singlepass
let mut config = Config::new();
config.wasm_simd(false); // or use Strategy::Cranelift

// On riscv64 singlepass, ensure SIMD is off before compiling.
if cfg!(target_arch = "riscv64") {
    config.wasm_simd(false);
    config.wasm_relaxed_simd(false);
}
// Or validate that module has no v128 ops:
let mut features = WasmFeatures::default();
features.simd = false;
wasmparser::Validator::new_with_features(features).validate_all(&wasm_bytes)?;

let result = std::panic::catch_unwind(|| {
    Module::new(&engine, &wasm_bytes)
});
match result {
    Ok(Ok(m)) => m,
    _ => return Err(CompileError::new("singlepass riscv: SIMD unsupported")),
}

When it happens

Trigger: Running wasm SIMD (v128) code through wasmtime's singlepass RISC-V backend; anything that calls `get_simd_arch` (EmitterRiscv impl at emitter_riscv.rs:354).

Common situations: Deploying wasmtime on RISC-V (riscv64) hardware and compiling modules that use wasm SIMD; enabling wasm_simd in config on RISC-V singlepass.

Related errors

• not yet implemented
• unsupported location
• not yet implemented
• Symbol {} in DWARF not recognized
• internal error: entered unreachable code

AI-assisted analysis of wasmerio/wasmer@8c4b9ee9d3 (2026-09-01). Data as JSON: /api/errors/a42a7cd9a9568ae2. Report an issue: GitHub.