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) {
     

src/midend/Pass/Optimize/DCE.cpp

@@ -74,6 +74,7 @@ void DCEContext::run(Function *func, AnalysisManager *AM, bool &changed) {
       }
     }
   }
+  changed |= SysYIROptUtils::eliminateRedundantPhisInFunction(func); // 如果有活跃指令，则标记为已更改
 }
 
 // 判断指令是否是"天然活跃"的实现

src/midend/Pass/Optimize/GVN.cpp

@@ -39,7 +39,7 @@ bool GVN::runOnFunction(Function *func, AnalysisManager &AM) {
     }
     std::cout << "=== GVN completed for function: " << func->getName() << " ===" << std::endl;
   }
-
+  changed |= SysYIROptUtils::eliminateRedundantPhisInFunction(func);
   return changed;
 }
 

src/midend/Pass/Optimize/InductionVariableElimination.cpp

@@ -133,6 +133,7 @@ bool InductionVariableEliminationContext::run(Function* F, AnalysisManager& AM)
     printDebugInfo();
   }
 
+  modified |= SysYIROptUtils::eliminateRedundantPhisInFunction(F);
   return modified;
 }
 

src/midend/Pass/Optimize/SCCP.cpp

@@ -1357,9 +1357,8 @@ void SCCPContext::run(Function *func, AnalysisManager &AM) {
   bool changed_control_flow = SimplifyControlFlow(func);
 
   // 如果任何一个阶段修改了 IR，标记分析结果为失效
-  if (changed_constant_propagation || changed_control_flow) {
-    // AM.invalidate(); // 假设有这样的方法来使所有分析结果失效
-  }
+  bool changed = changed_constant_propagation || changed_control_flow;
+  changed |= SysYIROptUtils::eliminateRedundantPhisInFunction(func);
 }
 
 // SCCP Pass methods