[midend-LICM]优化了特征分析中对循环不变量的识别，实现了LICM遍，格式化副作用分析代码

src/midend/Pass/Optimize/LICM.cpp

@@ -0,0 +1,84 @@
+#include "LICM.h"
+#include "IR.h"
+
+extern int DEBUG;
+
+namespace sysy {
+
+void *LICM::ID = (void *)&LICM::ID;
+
+bool LICMContext::run() { return hoistInstructions(); }
+
+bool LICMContext::hoistInstructions() {
+  bool changed = false;
+  BasicBlock *preheader = loop->getPreHeader();
+  if (!preheader || !chars){
+    if(DEBUG) {
+      std::cerr << "LICM: No preheader or loop characteristics found, skipping hoisting." << std::endl;
+    }
+    return false;
+  }
+    
+  for (auto *inst : chars->invariantInsts) {
+    if (!inst) {
+      if(DEBUG) {
+        std::cerr << "LICM: Invalid instruction found, skipping." << std::endl;
+      }
+      continue; // 跳过无效指令
+    }
+    else{
+      if(DEBUG) {
+        std::cout << "LICM: Processing instruction " << inst->getName() << " for hoisting." << std::endl;
+      }
+    }
+    BasicBlock *parent = inst->getParent();
+    // 只外提当前还在循环体内的指令
+    if (parent && loop->contains(parent)) {
+      // 获取源和槽的迭代器并移动指令到前置块
+      if(DEBUG) {
+        std::cout << "LICM: Hoisting instruction " << inst->getName() << " from " 
+                  << parent->getName() << " to preheader " << preheader->getName() << std::endl;
+      }
+      auto sourcePos = parent->findInstIterator(inst);
+      auto targetPos = preheader->terminator();
+      parent->moveInst(sourcePos, targetPos, preheader);
+      changed = true;
+    }
+  }
+  return changed;
+}
+
+// ---- LICM Pass Implementation ----
+
+bool LICM::runOnFunction(Function *F, AnalysisManager &AM) {
+  auto *loopAnalysis = AM.getAnalysisResult<LoopAnalysisResult, LoopAnalysisPass>(F);
+  auto *loopCharsResult = AM.getAnalysisResult<LoopCharacteristicsResult, LoopCharacteristicsPass>(F);
+  if (!loopAnalysis || !loopCharsResult)
+    return false;
+
+  bool changed = false;
+  // 对每个函数内的所有循环做处理
+  for (const auto &loop_ptr : loopAnalysis->getAllLoops()) {
+    Loop *loop = loop_ptr.get();
+    if(DEBUG){
+      std::cout << "LICM: Processing loop in function " << F->getName() << ": " << loop->getName() << std::endl;
+    }
+    const LoopCharacteristics *chars = loopCharsResult->getCharacteristics(loop);
+    if (!chars || !loop->getPreHeader())
+      continue; // 没有分析结果或没有前置块则跳过
+    LICMContext ctx(F, loop, builder, chars);
+    changed |= ctx.run();
+  }
+  return changed;
+}
+
+void LICM::getAnalysisUsage(std::set<void *> &analysisDependencies, std::set<void *> &analysisInvalidations) const {
+
+  analysisDependencies.insert(&LoopAnalysisPass::ID);
+  analysisDependencies.insert(&LoopCharacteristicsPass::ID);
+
+  analysisInvalidations.insert(&LoopCharacteristicsPass::ID);
+  analysisInvalidations.insert(&LivenessAnalysisPass::ID);
+}
+
+} // namespace sysy