diff --git a/src/wasm/encoder.h b/src/wasm/encoder.h
index 7b651bf..49a7bf7 100644
--- a/src/wasm/encoder.h
+++ b/src/wasm/encoder.h
@@ -42,11 +42,6 @@
   ZoneVector<uint8_t> body_;
   ZoneVector<char> name_;
 
-  bool HasLocals() const {
-    return (local_i32_count_ + local_i64_count_ + local_f32_count_ +
-            local_f64_count_) > 0;
-  }
-
   bool HasName() const { return (exported_ || external_) && name_.size() > 0; }
 };
 
@@ -60,8 +55,10 @@
                 const uint32_t* local_indices, uint32_t indices_size);
   void Emit(WasmOpcode opcode);
   void EmitWithU8(WasmOpcode opcode, const byte immediate);
-  uint32_t EmitEditableImmediate(const byte immediate);
-  void EditImmediate(uint32_t offset, const byte immediate);
+  void EmitWithU8U8(WasmOpcode opcode, const byte imm1, const byte imm2);
+  void EmitWithVarInt(WasmOpcode opcode, uint32_t immediate);
+  uint32_t EmitEditableVarIntImmediate();
+  void EditVarIntImmediate(uint32_t offset, const uint32_t immediate);
   void Exported(uint8_t flag);
   void External(uint8_t flag);
   void SetName(const unsigned char* name, int name_length);
@@ -120,6 +117,7 @@
   ZoneVector<FunctionSig*> signatures_;
   ZoneVector<uint16_t> indirect_functions_;
   ZoneVector<std::pair<MachineType, bool>> globals_;
+  int start_function_index_;
 };
 
 class WasmModuleBuilder : public ZoneObject {
@@ -131,6 +129,7 @@
   void AddDataSegment(WasmDataSegmentEncoder* data);
   uint16_t AddSignature(FunctionSig* sig);
   void AddIndirectFunction(uint16_t index);
+  void MarkStartFunction(uint16_t index);
   WasmModuleWriter* Build(Zone* zone);
 
   struct CompareFunctionSigs {
@@ -146,6 +145,7 @@
   ZoneVector<uint16_t> indirect_functions_;
   ZoneVector<std::pair<MachineType, bool>> globals_;
   SignatureMap signature_map_;
+  int start_function_index_;
 };
 
 std::vector<uint8_t> UnsignedLEB128From(uint32_t result);