Method new

winch/codegen/src/frame/mod.rs:47–75

Compute the local slots for a Wasm function.

(
        types: &impl TypeConvert,
        reader: &mut BinaryReader<'_>,
        validator: &mut FuncValidator<ValidatorResources>,
    )

impl DefinedLocals {
    /// Compute the local slots for a Wasm function.
    pub fn new<A: ABI>(
        types: &impl TypeConvert,
        reader: &mut BinaryReader<'_>,
        validator: &mut FuncValidator<ValidatorResources>,
    ) -> Result<Self> {
        let mut next_stack: u32 = 0;
        // The first 32 bits of a Wasm binary function describe the number of locals.
        let local_count = reader.read_var_u32()?;
        let mut slots: WasmLocals = Default::default();

        for _ in 0..local_count {
            let position = reader.original_position();
            let count = reader.read_var_u32()?;
            let ty = reader.read()?;
            validator.define_locals(position, count, ty)?;

            let ty = types.convert_valtype(ty)?;
            for _ in 0..count {
                let ty_size = <A as ABI>::sizeof(&ty);
                next_stack = align_to(next_stack, ty_size as u32) + (ty_size as u32);
                slots.push(LocalSlot::new(ty, next_stack));
            }
        }

        Ok(Self {
            defined_locals: slots,
            stack_size: next_stack,
        })
    }
}

/// Frame handler abstraction.