Method encode

crates/environ/src/fact.rs:779–842

Encodes this module into a WebAssembly binary.

(&mut self)

    /// Encodes this module into a WebAssembly binary.
    pub fn encode(&mut self) -> Vec<u8> {
        // Build the function/export sections of the wasm module in a first pass
        // which will assign a final `FuncIndex` to all functions defined in
        // `self.funcs`.
        let mut funcs = FunctionSection::new();
        let mut exports = ExportSection::new();
        let mut id_to_index = PrimaryMap::<FunctionId, FuncIndex>::new();
        for (id, func) in self.funcs.iter() {
            assert!(func.filled_in);
            let idx = FuncIndex::from_u32(self.imported_funcs.next_key().as_u32() + id.as_u32());
            let id2 = id_to_index.push(idx);
            assert_eq!(id2, id);

            funcs.function(func.ty);

            if let Some(name) = &func.export {
                exports.export(name, ExportKind::Func, idx.as_u32());
            }
        }
        for (idx, name) in &self.exports {
            exports.export(name, ExportKind::Func, *idx);
        }

        // With all functions numbered the fragments of the body of each
        // function can be assigned into one final adapter function.
        let mut code = CodeSection::new();
        for (_, func) in self.funcs.iter() {
            let mut body = Vec::new();

            // Encode all locals used for this function
            func.locals.len().encode(&mut body);
            for (count, ty) in func.locals.iter() {
                count.encode(&mut body);
                ty.encode(&mut body);
            }

            // Then encode each "chunk" of a body which may have optional traps
            // specified within it. Traps get offset by the current length of
            // the body and otherwise our `Call` instructions are "relocated"
            // here to the final function index.
            for chunk in func.body.iter() {
                match chunk {
                    Body::Raw(code) => {
                        body.extend_from_slice(code);
                    }
                    Body::Call(id) => {
                        Instruction::Call(id_to_index[*id].as_u32()).encode(&mut body);
                    }
                    Body::RefFunc(id) => {
                        Instruction::RefFunc(id_to_index[*id].as_u32()).encode(&mut body);
                    }
                }
            }
            code.raw(&body);
        }

        let mut result = wasm_encoder::Module::new();
        result.section(&self.core_types.section);