[backend] incorrect asm output

src/RISCv32Backend.h

@@ -19,6 +19,7 @@ private:
 
     // 物理寄存器
     enum class PhysicalReg {
+        S0, // x8, 帧指针
         T0, T1, T2, T3, T4, T5, T6, // x5-x7, x28-x31
         A0, A1, A2, A3, A4, A5, A6, A7 // x10-x17
     };
@@ -53,7 +54,7 @@ private:
     std::string module_gen();
     std::string function_gen(Function* func);
     std::string basicBlock_gen(BasicBlock* bb, const RegAllocResult& alloc);
-    std::vector<RISCv32Inst> instruction_gen(Instruction* inst);
+    std::vector<std::string> instruction_gen(Instruction* inst, const RegAllocResult& alloc);
     RegAllocResult register_allocation(Function* func);
     void eliminate_phi(Function* func);
     std::map<Instruction*, std::set<Value*>> liveness_analysis(Function* func);