[midend-phielimination]增加phi指令消除检查

src/include/midend/Pass/Optimize/SysYIROptUtils.h

@@ -109,6 +109,28 @@ public:
   }
 
   
+  // PHI指令消除相关方法
+  static void eliminateRedundantPhisInFunction(Function* func){
+    std::vector<Instruction *> toDelete;
+    for (auto &bb : func->getBasicBlocks()) {
+      for (auto &inst : bb->getInstructions()) {
+        if (auto phi = dynamic_cast<PhiInst *>(inst.get())) {
+          auto incoming = phi->getIncomingValues();
+          if (incoming.size() == 1) {
+            Value *singleVal = incoming[0].first;
+            inst->replaceAllUsesWith(singleVal);
+            toDelete.push_back(inst.get());
+          }
+        }
+        else
+          break; // 只处理Phi指令
+      }
+    }
+    for (auto *phi : toDelete) {
+      usedelete(phi);
+    }
+  }
+
   //该实现参考了libdivide的算法
   static std::pair<int, int> computeMulhMagicNumbers(int divisor) {