Merge branch 'midend' into backend-O1-1

src/include/midend/IR.h

@@ -1007,6 +1007,7 @@ class PhiInst : public Instruction {
   void replaceIncomingBlock(BasicBlock *oldBlock, BasicBlock *newBlock, Value *newValue);
   void refreshMap() {
     blk2val.clear();
+    vsize = getNumOperands() / 2;
     for (unsigned i = 0; i < vsize; ++i) {
       blk2val[getIncomingBlock(i)] = getIncomingValue(i);
     }

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

@@ -109,6 +109,34 @@ public:
   }
 
   
+  // PHI指令消除相关方法
+  static bool eliminateRedundantPhisInFunction(Function* func){
+    bool changed = false;
+    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(DEBUG){
+            std::cout << "Checking Phi: " << phi->getName() << " with " << incoming.size() << " incoming values." << std::endl;
+          }
+          if (incoming.size() == 1) {
+            Value *singleVal = incoming[0].second;
+            inst->replaceAllUsesWith(singleVal);
+            toDelete.push_back(inst.get());
+          }
+        }
+        else
+          break; // 只处理Phi指令
+      }
+    }
+    for (auto *phi : toDelete) {
+      usedelete(phi);
+      changed = true; // 标记为已更改
+    }
+    return changed; // 返回是否有删除发生
+  }
+
   //该实现参考了libdivide的算法
   static std::pair<int, int> computeMulhMagicNumbers(int divisor) {