[midend-SCCP]bug修复，增加不可达指令（理论来说后端不会出现这条指令，只是为了IR完整性添加），添加相关方法，phi指令方法修复；目前能够跑完所有优化，但是User的析构函数重定义导致全局析构不能正确完成，需要修复

src/midend/Pass/Pass.cpp

@@ -83,11 +83,19 @@ void PassManager::runOptimizationPipeline(Module* moduleIR, IRBuilder* builderIR
 
       this->clearPasses();
       this->addPass(&Mem2Reg::ID);
+      this->run();
+
+      if(DEBUG) {
+        std::cout << "=== IR After Mem2Reg Optimizations ===\n";
+        printPasses();
+      }
+
+      this->clearPasses();
       this->addPass(&SCCP::ID);
       this->run();
 
       if(DEBUG) {
-        std::cout << "=== IR After Mem2Reg And SCCP Optimizations ===\n";
+        std::cout << "=== IR After SCCP Optimizations ===\n";
         printPasses();
       }