src/SysYIRCFGOpt.cpp

@@ -13,248 +13,374 @@ namespace sysy {
 
 
 // 删除br后的无用指令
-void SysYCFGOpt::SysYDelInstAfterBr() {
-  auto &functions = pModule->getFunctions();
-  for (auto &function : functions) {
-    auto basicBlocks = function.second->getBasicBlocks();
-    for (auto &basicBlock : basicBlocks) {
-      bool Branch = false;
-      auto &instructions = basicBlock->getInstructions();
-      auto Branchiter = instructions.end();
-      for (auto iter = instructions.begin(); iter != instructions.end(); ++iter) {
-        if (Branch) 
-          SysYIROptUtils::usedelete(iter->get());
-        else if ((*iter)->isTerminator()){
-          Branch = true;
-          Branchiter = iter;
-        }
+bool SysYCFGOpt::SysYDelInstAfterBr(Function *func) {
+  bool changed = false;
+  
+  auto basicBlocks = func->getBasicBlocks();
+  for (auto &basicBlock : basicBlocks) {
+    bool Branch = false;
+    auto &instructions = basicBlock->getInstructions();
+    auto Branchiter = instructions.end();
+    for (auto iter = instructions.begin(); iter != instructions.end(); ++iter) {
+      if (Branch) 
+        SysYIROptUtils::usedelete(iter->get());
+      else if ((*iter)->isTerminator()){
+        Branch = true;
+        Branchiter = iter;
       }
-      if (Branchiter != instructions.end()) ++Branchiter;
-      while (Branchiter != instructions.end()) 
-        Branchiter = instructions.erase(Branchiter);
-      
-      if (Branch) {  // 更新前驱后继关系
-        auto thelastinstinst = basicBlock->getInstructions().end();
-        --thelastinstinst;
-        auto &Successors = basicBlock->getSuccessors();
-        for (auto iterSucc = Successors.begin(); iterSucc != Successors.end();) {
-          (*iterSucc)->removePredecessor(basicBlock.get());
-          basicBlock->removeSuccessor(*iterSucc);
-        }
-        if (thelastinstinst->get()->isUnconditional()) {
-          BasicBlock* branchBlock = dynamic_cast<BasicBlock *>(thelastinstinst->get()->getOperand(0));
-          basicBlock->addSuccessor(branchBlock);
-          branchBlock->addPredecessor(basicBlock.get());
-        } else if (thelastinstinst->get()->isConditional()) {
-          BasicBlock* thenBlock = dynamic_cast<BasicBlock *>(thelastinstinst->get()->getOperand(1));
-          BasicBlock* elseBlock = dynamic_cast<BasicBlock *>(thelastinstinst->get()->getOperand(2));
-          basicBlock->addSuccessor(thenBlock);
-          basicBlock->addSuccessor(elseBlock);
-          thenBlock->addPredecessor(basicBlock.get());
-          elseBlock->addPredecessor(basicBlock.get());
-        }
+    }
+    if (Branchiter != instructions.end()) ++Branchiter;
+    while (Branchiter != instructions.end()) {
+      changed = true;
+      Branchiter = instructions.erase(Branchiter);
+    }
+    
+    if (Branch) {  // 更新前驱后继关系
+      auto thelastinstinst = basicBlock->getInstructions().end();
+      --thelastinstinst;
+      auto &Successors = basicBlock->getSuccessors();
+      for (auto iterSucc = Successors.begin(); iterSucc != Successors.end();) {
+        (*iterSucc)->removePredecessor(basicBlock.get());
+        basicBlock->removeSuccessor(*iterSucc);
+      }
+      if (thelastinstinst->get()->isUnconditional()) {
+        BasicBlock* branchBlock = dynamic_cast<BasicBlock *>(thelastinstinst->get()->getOperand(0));
+        basicBlock->addSuccessor(branchBlock);
+        branchBlock->addPredecessor(basicBlock.get());
+      } else if (thelastinstinst->get()->isConditional()) {
+        BasicBlock* thenBlock = dynamic_cast<BasicBlock *>(thelastinstinst->get()->getOperand(1));
+        BasicBlock* elseBlock = dynamic_cast<BasicBlock *>(thelastinstinst->get()->getOperand(2));
+        basicBlock->addSuccessor(thenBlock);
+        basicBlock->addSuccessor(elseBlock);
+        thenBlock->addPredecessor(basicBlock.get());
+        elseBlock->addPredecessor(basicBlock.get());
       }
     }
   }
+
+  return changed;
 }
 
 // 合并空基本块
-void SysYCFGOpt::SysYBlockMerge() {
-  auto &functions = pModule->getFunctions(); //std::map<std::string, std::unique_ptr<Function>>
-  for (auto &function : functions) {
-    // auto basicBlocks = function.second->getBasicBlocks();
-    auto &func = function.second;
-    for (auto blockiter = func->getBasicBlocks().begin();
-         blockiter != func->getBasicBlocks().end();) {
-      if (blockiter->get()->getNumSuccessors() == 1) {
-        // 如果当前块只有一个后继块
-        // 且后继块只有一个前驱块
-        // 则将当前块和后继块合并
-        if (((blockiter->get())->getSuccessors()[0])->getNumPredecessors() == 1) {
-          // std::cout << "merge block: " << blockiter->get()->getName() << std::endl;
-          BasicBlock* block = blockiter->get();
-          BasicBlock* nextBlock = blockiter->get()->getSuccessors()[0];
-          auto nextarguments = nextBlock->getArguments();
-          // 删除br指令
-          if (block->getNumInstructions() != 0) {
-            auto thelastinstinst = block->end();
-            (--thelastinstinst);
-            if (thelastinstinst->get()->isUnconditional()) {
+bool SysYCFGOpt::SysYBlockMerge(Function *func) {
+  bool changed = false;
+
+  for (auto blockiter = func->getBasicBlocks().begin();
+        blockiter != func->getBasicBlocks().end();) {
+    if (blockiter->get()->getNumSuccessors() == 1) {
+      // 如果当前块只有一个后继块
+      // 且后继块只有一个前驱块
+      // 则将当前块和后继块合并
+      if (((blockiter->get())->getSuccessors()[0])->getNumPredecessors() == 1) {
+        // std::cout << "merge block: " << blockiter->get()->getName() << std::endl;
+        BasicBlock* block = blockiter->get();
+        BasicBlock* nextBlock = blockiter->get()->getSuccessors()[0];
+        auto nextarguments = nextBlock->getArguments();
+        // 删除br指令
+        if (block->getNumInstructions() != 0) {
+          auto thelastinstinst = block->end();
+          (--thelastinstinst);
+          if (thelastinstinst->get()->isUnconditional()) {
+            SysYIROptUtils::usedelete(thelastinstinst->get());
+            block->getInstructions().erase(thelastinstinst);
+          } else if (thelastinstinst->get()->isConditional()) {
+            // 如果是条件分支，判断条件是否相同，主要优化相同布尔表达式
+            if (thelastinstinst->get()->getOperand(1)->getName() == thelastinstinst->get()->getOperand(1)->getName()) {
               SysYIROptUtils::usedelete(thelastinstinst->get());
               block->getInstructions().erase(thelastinstinst);
-            } else if (thelastinstinst->get()->isConditional()) {
-              // 如果是条件分支，判断条件是否相同，主要优化相同布尔表达式
-              if (thelastinstinst->get()->getOperand(1)->getName() == thelastinstinst->get()->getOperand(1)->getName()) {
-                SysYIROptUtils::usedelete(thelastinstinst->get());
-                block->getInstructions().erase(thelastinstinst);
-              }
             }
           }
-          // 将后继块的指令移动到当前块
-          // 并将后继块的父指针改为当前块
-          for (auto institer = nextBlock->begin(); institer != nextBlock->end();) {
-            institer->get()->setParent(block);
-            block->getInstructions().emplace_back(institer->release());
-            institer = nextBlock->getInstructions().erase(institer);   
-          }
-          // 合并参数
-          // TODO：是否需要去重?
-          for (auto &argm : nextarguments) {
-            argm->setParent(block);
-            block->insertArgument(argm);
-          }
-          // 更新前驱后继关系，类似树节点操作
-          block->removeSuccessor(nextBlock);
-          nextBlock->removePredecessor(block);
-          std::list<BasicBlock *> succshoulddel;
-          for (auto &succ : nextBlock->getSuccessors()) {
-            block->addSuccessor(succ);
-            succ->replacePredecessor(nextBlock, block);
-            succshoulddel.push_back(succ);
-          }
-          for (auto del : succshoulddel) {
-            nextBlock->removeSuccessor(del);
-          }
-
-          func->removeBasicBlock(nextBlock);
-
-        } else {
-          blockiter++;
         }
+        // 将后继块的指令移动到当前块
+        // 并将后继块的父指针改为当前块
+        for (auto institer = nextBlock->begin(); institer != nextBlock->end();) {
+          institer->get()->setParent(block);
+          block->getInstructions().emplace_back(institer->release());
+          institer = nextBlock->getInstructions().erase(institer);   
+        }
+        // 合并参数
+        // TODO：是否需要去重?
+        for (auto &argm : nextarguments) {
+          argm->setParent(block);
+          block->insertArgument(argm);
+        }
+        // 更新前驱后继关系，类似树节点操作
+        block->removeSuccessor(nextBlock);
+        nextBlock->removePredecessor(block);
+        std::list<BasicBlock *> succshoulddel;
+        for (auto &succ : nextBlock->getSuccessors()) {
+          block->addSuccessor(succ);
+          succ->replacePredecessor(nextBlock, block);
+          succshoulddel.push_back(succ);
+        }
+        for (auto del : succshoulddel) {
+          nextBlock->removeSuccessor(del);
+        }
+
+        func->removeBasicBlock(nextBlock);
+        changed = true;
+
       } else {
         blockiter++;
       }
+    } else {
+      blockiter++;
     }
   }
+
+  return changed;
 }
 
 // 删除无前驱块，兼容SSA后的处理
-void SysYCFGOpt::SysYDelNoPreBLock() {
+bool SysYCFGOpt::SysYDelNoPreBLock(Function *func) {
   
-  auto &functions = pModule->getFunctions(); // std::map<std::string, std::unique_ptr<sysy::Function>>
-  for (auto &function : functions) {
-    auto &func = function.second;
+  bool changed = false;
 
-    for (auto &block : func->getBasicBlocks()) {
-      block->setreachableFalse();
-    }
-    // 对函数基本块做一个拓扑排序，排查不可达基本块
-    auto entryBlock = func->getEntryBlock();
-    entryBlock->setreachableTrue();
-    std::queue<BasicBlock *> blockqueue;
-    blockqueue.push(entryBlock);
-    while (!blockqueue.empty()) {
-      auto block = blockqueue.front();
-      blockqueue.pop();
-      for (auto &succ : block->getSuccessors()) {
-        if (!succ->getreachable()) {
-          succ->setreachableTrue();
-          blockqueue.push(succ);
-        }
-      }
-    }
-
-    // 删除不可达基本块指令
-    for (auto blockIter = func->getBasicBlocks().begin(); blockIter != func->getBasicBlocks().end();blockIter++) {
-      
-      if (!blockIter->get()->getreachable()) 
-        for (auto &iterInst : blockIter->get()->getInstructions()) 
-          SysYIROptUtils::usedelete(iterInst.get());
-    
-    }
-
-    
-    for (auto blockIter = func->getBasicBlocks().begin(); blockIter != func->getBasicBlocks().end();) {
-      if (!blockIter->get()->getreachable()) {
-        for (auto succblock : blockIter->get()->getSuccessors()) {
-          int indexphi = 1;
-          for (auto pred : succblock->getPredecessors()) {
-            if (pred == blockIter->get()) {
-              break;
-            }
-            indexphi++;
-          }
-          for (auto &phiinst : succblock->getInstructions()) {
-            if (phiinst->getKind() != Instruction::kPhi) {
-              break;
-            }
-            phiinst->removeOperand(indexphi);
-          }
-        }
-        // 删除不可达基本块，注意迭代器不可达问题
-        func->removeBasicBlock((blockIter++)->get());
-      } else {
-        blockIter++;
+  for (auto &block : func->getBasicBlocks()) {
+    block->setreachableFalse();
+  }
+  // 对函数基本块做一个拓扑排序，排查不可达基本块
+  auto entryBlock = func->getEntryBlock();
+  entryBlock->setreachableTrue();
+  std::queue<BasicBlock *> blockqueue;
+  blockqueue.push(entryBlock);
+  while (!blockqueue.empty()) {
+    auto block = blockqueue.front();
+    blockqueue.pop();
+    for (auto &succ : block->getSuccessors()) {
+      if (!succ->getreachable()) {
+        succ->setreachableTrue();
+        blockqueue.push(succ);
       }
     }
   }
-}
 
-void SysYCFGOpt::SysYDelEmptyBlock() {
-  auto &functions = pModule->getFunctions();
-  for (auto &function : functions) {
-    // 收集不可达基本块
-    // 这里的不可达基本块是指没有实际指令的基本块
-    // 当一个基本块没有实际指令例如只有phi指令和一个uncondbr指令时，也会被视作不可达
-    auto basicBlocks = function.second->getBasicBlocks();
-    std::map<sysy::BasicBlock *, BasicBlock *> EmptyBlocks;
-    // 空块儿和后继的基本块的映射
-    for (auto &basicBlock : basicBlocks) {
-      if (basicBlock->getNumInstructions() == 0) {
-        if (basicBlock->getNumSuccessors() == 1) {
-          EmptyBlocks[basicBlock.get()] = basicBlock->getSuccessors().front();
+  // 删除不可达基本块指令
+  for (auto blockIter = func->getBasicBlocks().begin(); blockIter != func->getBasicBlocks().end();blockIter++) {
+    if (!blockIter->get()->getreachable()) 
+      for (auto &iterInst : blockIter->get()->getInstructions()) 
+        SysYIROptUtils::usedelete(iterInst.get());
+  
+  }
+
+  
+  for (auto blockIter = func->getBasicBlocks().begin(); blockIter != func->getBasicBlocks().end();) {
+    if (!blockIter->get()->getreachable()) {
+      for (auto succblock : blockIter->get()->getSuccessors()) {
+        int indexphi = 1;
+        for (auto pred : succblock->getPredecessors()) {
+          if (pred == blockIter->get()) {
+            break;
+          }
+          indexphi++;
+        }
+        for (auto &phiinst : succblock->getInstructions()) {
+          if (phiinst->getKind() != Instruction::kPhi) {
+            break;
+          }
+          phiinst->removeOperand(indexphi);
         }
       }
-      else{
-        // 如果只有phi指令和一个uncondbr。(phi)*(uncondbr)?
-          // 判断除了最后一个指令之外是不是只有phi指令
-        bool onlyPhi = true;
-        for (auto &inst : basicBlock->getInstructions()) {
-          if (!inst->isPhi() && !inst->isUnconditional()) {
-            onlyPhi = false;
+      // 删除不可达基本块，注意迭代器不可达问题
+      func->removeBasicBlock((blockIter++)->get());
+      changed = true;
+    } else {
+      blockIter++;
+    }
+  }
+  
+  return changed;
+}
+
+// 删除空块
+bool SysYCFGOpt::SysYDelEmptyBlock(Function *func, IRBuilder* pBuilder) {
+  bool changed = false;
+
+  // 收集不可达基本块
+  // 这里的不可达基本块是指没有实际指令的基本块
+  // 当一个基本块没有实际指令例如只有phi指令和一个uncondbr指令时，也会被视作不可达
+  auto basicBlocks = func->getBasicBlocks();
+  std::map<sysy::BasicBlock *, BasicBlock *> EmptyBlocks;
+  // 空块儿和后继的基本块的映射
+  for (auto &basicBlock : basicBlocks) {
+    if (basicBlock->getNumInstructions() == 0) {
+      if (basicBlock->getNumSuccessors() == 1) {
+        EmptyBlocks[basicBlock.get()] = basicBlock->getSuccessors().front();
+      }
+    }
+    else{
+      // 如果只有phi指令和一个uncondbr。(phi)*(uncondbr)?
+        // 判断除了最后一个指令之外是不是只有phi指令
+      bool onlyPhi = true;
+      for (auto &inst : basicBlock->getInstructions()) {
+        if (!inst->isPhi() && !inst->isUnconditional()) {
+          onlyPhi = false;
+          break;
+        }
+      }
+      if(onlyPhi)
+        EmptyBlocks[basicBlock.get()] = basicBlock->getSuccessors().front();
+    }
+    
+    
+  }
+  // 更新基本块信息，增加必要指令
+  for (auto &basicBlock : basicBlocks) {
+    // 把空块转换成只有跳转指令的不可达块
+    if (distance(basicBlock->begin(), basicBlock->end()) == 0) {
+      if (basicBlock->getNumSuccessors() == 0) {
+        continue;
+      }
+      if (basicBlock->getNumSuccessors() > 1) {
+        assert("");
+      }
+      pBuilder->setPosition(basicBlock.get(), basicBlock->end());
+      pBuilder->createUncondBrInst(basicBlock->getSuccessors()[0], {});
+      continue;
+    }
+
+    auto thelastinst = basicBlock->getInstructions().end();
+    --thelastinst;
+
+    // 根据br指令传递的后继块信息，跳过空块链
+    if (thelastinst->get()->isUnconditional()) {
+      BasicBlock* OldBrBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0));
+      BasicBlock *thelastBlockOld = nullptr;
+      // 如果空块链表为多个块
+      while (EmptyBlocks.find(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))) !=
+              EmptyBlocks.end()) {
+        thelastBlockOld = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0));
+        thelastinst->get()->replaceOperand(0, EmptyBlocks[thelastBlockOld]);
+      }
+
+      basicBlock->removeSuccessor(OldBrBlock);
+      OldBrBlock->removePredecessor(basicBlock.get());
+      basicBlock->addSuccessor(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0)));
+      dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->addPredecessor(basicBlock.get());
+
+      if (thelastBlockOld != nullptr) {
+        int indexphi = 0;
+        for (auto &pred : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getPredecessors()) {
+          if (pred == thelastBlockOld) {
+            break;
+          }
+          indexphi++;
+        }
+
+        // 更新phi指令的操作数
+        // 移除thelastBlockOld对应的phi操作数
+        for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getInstructions()) {
+          if (InstInNew->isPhi()) {
+            dynamic_cast<PhiInst *>(InstInNew.get())->removeOperand(indexphi + 1);
+          } else {
             break;
           }
         }
-        if(onlyPhi)
-          EmptyBlocks[basicBlock.get()] = basicBlock->getSuccessors().front();
       }
-      
-      
-    }
-    // 更新基本块信息，增加必要指令
-    for (auto &basicBlock : basicBlocks) {
-      // 把空块转换成只有跳转指令的不可达块
-      if (distance(basicBlock->begin(), basicBlock->end()) == 0) {
-        if (basicBlock->getNumSuccessors() == 0) {
-          continue;
-        }
-        if (basicBlock->getNumSuccessors() > 1) {
-          assert("");
-        }
+
+    } else if (thelastinst->get()->getKind() == Instruction::kCondBr) {
+      auto OldThenBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1));
+      auto OldElseBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2));
+
+      BasicBlock *thelastBlockOld = nullptr;
+      while (EmptyBlocks.find(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))) !=
+              EmptyBlocks.end()) {
+        thelastBlockOld = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1));
+        thelastinst->get()->replaceOperand(
+            1, EmptyBlocks[dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))]);
+      }
+      basicBlock->removeSuccessor(OldThenBlock);
+      OldThenBlock->removePredecessor(basicBlock.get());
+      // 处理 then 和 else 分支合并的情况
+      if (dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1)) ==
+          dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))) {
+        auto thebrBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1));
+        SysYIROptUtils::usedelete(thelastinst->get());
+        thelastinst = basicBlock->getInstructions().erase(thelastinst);
         pBuilder->setPosition(basicBlock.get(), basicBlock->end());
-        pBuilder->createUncondBrInst(basicBlock->getSuccessors()[0], {});
+        pBuilder->createUncondBrInst(thebrBlock, {});
         continue;
       }
+      basicBlock->addSuccessor(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1)));
+      dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))->addPredecessor(basicBlock.get());
+      // auto indexInNew = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getPredecessors().
 
-      auto thelastinst = basicBlock->getInstructions().end();
-      --thelastinst;
-
-      // 根据br指令传递的后继块信息，跳过空块链
-      if (thelastinst->get()->isUnconditional()) {
-        BasicBlock* OldBrBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0));
-        BasicBlock *thelastBlockOld = nullptr;
-        // 如果空块链表为多个块
-        while (EmptyBlocks.find(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))) !=
-               EmptyBlocks.end()) {
-          thelastBlockOld = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0));
-          thelastinst->get()->replaceOperand(0, EmptyBlocks[thelastBlockOld]);
+      if (thelastBlockOld != nullptr) {
+        int indexphi = 0;
+        for (auto &pred : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))->getPredecessors()) {
+          if (pred == thelastBlockOld) {
+            break;
+          }
+          indexphi++;
         }
 
+        for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))->getInstructions()) {
+          if (InstInNew->isPhi()) {
+            dynamic_cast<PhiInst *>(InstInNew.get())->removeOperand(indexphi + 1);
+          } else {
+            break;
+          }
+        }
+      }
+
+      thelastBlockOld = nullptr;
+      while (EmptyBlocks.find(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))) !=
+              EmptyBlocks.end()) {
+        thelastBlockOld = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2));
+        thelastinst->get()->replaceOperand(
+            2, EmptyBlocks[dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))]);
+      }
+      basicBlock->removeSuccessor(OldElseBlock);
+      OldElseBlock->removePredecessor(basicBlock.get());
+      // 处理 then 和 else 分支合并的情况
+      if (dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1)) ==
+          dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))) {
+        auto thebrBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1));
+        SysYIROptUtils::usedelete(thelastinst->get());
+        thelastinst = basicBlock->getInstructions().erase(thelastinst);
+        pBuilder->setPosition(basicBlock.get(), basicBlock->end());
+        pBuilder->createUncondBrInst(thebrBlock, {});
+        continue;
+      }
+      basicBlock->addSuccessor(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2)));
+      dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))->addPredecessor(basicBlock.get());
+
+      if (thelastBlockOld != nullptr) {
+        int indexphi = 0;
+        for (auto &pred : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))->getPredecessors()) {
+          if (pred == thelastBlockOld) {
+            break;
+          }
+          indexphi++;
+        }
+        for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))->getInstructions()) {
+          if (InstInNew->isPhi()) {
+            dynamic_cast<PhiInst *>(InstInNew.get())->removeOperand(indexphi + 1);
+          } else {
+            break;
+          }
+        }
+      }
+    } else {
+      if (basicBlock->getNumSuccessors() == 1) {
+        pBuilder->setPosition(basicBlock.get(), basicBlock->end());
+        pBuilder->createUncondBrInst(basicBlock->getSuccessors()[0], {});
+        auto thelastinst = basicBlock->getInstructions().end();
+        (--thelastinst);
+        auto OldBrBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0));
+        sysy::BasicBlock *thelastBlockOld = nullptr;
+        while (EmptyBlocks.find(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))) !=
+                EmptyBlocks.end()) {
+          thelastBlockOld = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0));
+
+          thelastinst->get()->replaceOperand(
+              0, EmptyBlocks[dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))]);
+        }
+        
         basicBlock->removeSuccessor(OldBrBlock);
         OldBrBlock->removePredecessor(basicBlock.get());
         basicBlock->addSuccessor(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0)));
         dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->addPredecessor(basicBlock.get());
-
         if (thelastBlockOld != nullptr) {
           int indexphi = 0;
           for (auto &pred : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getPredecessors()) {
@@ -264,8 +390,6 @@ void SysYCFGOpt::SysYDelEmptyBlock() {
             indexphi++;
           }
 
-          // 更新phi指令的操作数
-          // 移除thelastBlockOld对应的phi操作数
           for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getInstructions()) {
             if (InstInNew->isPhi()) {
               dynamic_cast<PhiInst *>(InstInNew.get())->removeOperand(indexphi + 1);
@@ -274,200 +398,82 @@ void SysYCFGOpt::SysYDelEmptyBlock() {
             }
           }
         }
-
-      } else if (thelastinst->get()->getKind() == Instruction::kCondBr) {
-        auto OldThenBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1));
-        auto OldElseBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2));
-
-        BasicBlock *thelastBlockOld = nullptr;
-        while (EmptyBlocks.find(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))) !=
-               EmptyBlocks.end()) {
-          thelastBlockOld = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1));
-          thelastinst->get()->replaceOperand(
-              1, EmptyBlocks[dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))]);
-        }
-        basicBlock->removeSuccessor(OldThenBlock);
-        OldThenBlock->removePredecessor(basicBlock.get());
-        // 处理 then 和 else 分支合并的情况
-        if (dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1)) ==
-            dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))) {
-          auto thebrBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1));
-          SysYIROptUtils::usedelete(thelastinst->get());
-          thelastinst = basicBlock->getInstructions().erase(thelastinst);
-          pBuilder->setPosition(basicBlock.get(), basicBlock->end());
-          pBuilder->createUncondBrInst(thebrBlock, {});
-          continue;
-        }
-        basicBlock->addSuccessor(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1)));
-        dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))->addPredecessor(basicBlock.get());
-        // auto indexInNew = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getPredecessors().
-
-        if (thelastBlockOld != nullptr) {
-          int indexphi = 0;
-          for (auto &pred : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))->getPredecessors()) {
-            if (pred == thelastBlockOld) {
-              break;
-            }
-            indexphi++;
-          }
-
-          for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))->getInstructions()) {
-            if (InstInNew->isPhi()) {
-              dynamic_cast<PhiInst *>(InstInNew.get())->removeOperand(indexphi + 1);
-            } else {
-              break;
-            }
-          }
-        }
-
-        thelastBlockOld = nullptr;
-        while (EmptyBlocks.find(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))) !=
-               EmptyBlocks.end()) {
-          thelastBlockOld = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2));
-          thelastinst->get()->replaceOperand(
-              2, EmptyBlocks[dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))]);
-        }
-        basicBlock->removeSuccessor(OldElseBlock);
-        OldElseBlock->removePredecessor(basicBlock.get());
-        // 处理 then 和 else 分支合并的情况
-        if (dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1)) ==
-            dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))) {
-          auto thebrBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1));
-          SysYIROptUtils::usedelete(thelastinst->get());
-          thelastinst = basicBlock->getInstructions().erase(thelastinst);
-          pBuilder->setPosition(basicBlock.get(), basicBlock->end());
-          pBuilder->createUncondBrInst(thebrBlock, {});
-          continue;
-        }
-        basicBlock->addSuccessor(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2)));
-        dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))->addPredecessor(basicBlock.get());
-
-        if (thelastBlockOld != nullptr) {
-          int indexphi = 0;
-          for (auto &pred : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))->getPredecessors()) {
-            if (pred == thelastBlockOld) {
-              break;
-            }
-            indexphi++;
-          }
-          for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))->getInstructions()) {
-            if (InstInNew->isPhi()) {
-              dynamic_cast<PhiInst *>(InstInNew.get())->removeOperand(indexphi + 1);
-            } else {
-              break;
-            }
-          }
-        }
-      } else {
-        if (basicBlock->getNumSuccessors() == 1) {
-          pBuilder->setPosition(basicBlock.get(), basicBlock->end());
-          pBuilder->createUncondBrInst(basicBlock->getSuccessors()[0], {});
-          auto thelastinst = basicBlock->getInstructions().end();
-          (--thelastinst);
-          auto OldBrBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0));
-          sysy::BasicBlock *thelastBlockOld = nullptr;
-          while (EmptyBlocks.find(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))) !=
-                 EmptyBlocks.end()) {
-            thelastBlockOld = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0));
-
-            thelastinst->get()->replaceOperand(
-                0, EmptyBlocks[dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))]);
-          }
-          
-          basicBlock->removeSuccessor(OldBrBlock);
-          OldBrBlock->removePredecessor(basicBlock.get());
-          basicBlock->addSuccessor(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0)));
-          dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->addPredecessor(basicBlock.get());
-          if (thelastBlockOld != nullptr) {
-            int indexphi = 0;
-            for (auto &pred : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getPredecessors()) {
-              if (pred == thelastBlockOld) {
-                break;
-              }
-              indexphi++;
-            }
-
-            for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getInstructions()) {
-              if (InstInNew->isPhi()) {
-                dynamic_cast<PhiInst *>(InstInNew.get())->removeOperand(indexphi + 1);
-              } else {
-                break;
-              }
-            }
-          }
-        }
-      }
-    }
-
-    for (auto iter = function.second->getBasicBlocks().begin(); iter != function.second->getBasicBlocks().end();) {
-      
-      if (EmptyBlocks.find(iter->get()) != EmptyBlocks.end()) {
-        // EntryBlock跳过
-        if (iter->get() == function.second->getEntryBlock()) {
-          ++iter;
-          continue;
-        }
-
-        for (auto &iterInst : iter->get()->getInstructions()) 
-          SysYIROptUtils::usedelete(iterInst.get());
-        // 删除不可达基本块的phi指令的操作数
-        for (auto &succ : iter->get()->getSuccessors()) {
-          int index = 0;
-          for (auto &pred : succ->getPredecessors()) {
-            if (pred == iter->get()) {
-              break;
-            }
-            index++;
-          }
-
-          for (auto &instinsucc : succ->getInstructions()) {
-            if (instinsucc->isPhi()) {
-              dynamic_cast<PhiInst *>(instinsucc.get())->removeOperand(index);
-            } else {
-              break;
-            }
-          }
-        }
-
-        function.second->removeBasicBlock((iter++)->get());
-      } else {
-        ++iter;
       }
     }
   }
+
+  for (auto iter = func->getBasicBlocks().begin(); iter != func->getBasicBlocks().end();) {
+    
+    if (EmptyBlocks.find(iter->get()) != EmptyBlocks.end()) {
+      // EntryBlock跳过
+      if (iter->get() == func->getEntryBlock()) {
+        ++iter;
+        continue;
+      }
+
+      for (auto &iterInst : iter->get()->getInstructions()) 
+        SysYIROptUtils::usedelete(iterInst.get());
+      // 删除不可达基本块的phi指令的操作数
+      for (auto &succ : iter->get()->getSuccessors()) {
+        int index = 0;
+        for (auto &pred : succ->getPredecessors()) {
+          if (pred == iter->get()) {
+            break;
+          }
+          index++;
+        }
+
+        for (auto &instinsucc : succ->getInstructions()) {
+          if (instinsucc->isPhi()) {
+            dynamic_cast<PhiInst *>(instinsucc.get())->removeOperand(index);
+          } else {
+            break;
+          }
+        }
+      }
+
+      func->removeBasicBlock((iter++)->get());
+      changed = true;
+    } else {
+      ++iter;
+    }
+  }
+  
+  return changed;
+
 }
 
 // 如果函数没有返回指令，则添加一个默认返回指令(主要解决void函数没有返回指令的问题)
-void SysYCFGOpt::SysYAddReturn() {
-  auto &functions = pModule->getFunctions();
-  for (auto &function : functions) {
-    auto &func = function.second;
-    auto basicBlocks = func->getBasicBlocks();
-    for (auto &block : basicBlocks) {
-      if (block->getNumSuccessors() == 0) {
-        // 如果基本块没有后继块，则添加一个返回指令
-        if (block->getNumInstructions() == 0) {
-          pBuilder->setPosition(block.get(), block->end());
-          pBuilder->createReturnInst();
-        }
-        auto thelastinst = block->getInstructions().end();
-        --thelastinst;
-        if (thelastinst->get()->getKind() != Instruction::kReturn) {
-          // std::cout << "Warning: Function " << func->getName() << " has no return instruction, adding default return." << std::endl;
+bool SysYCFGOpt::SysYAddReturn(Function *func, IRBuilder* pBuilder) {
+  bool changed = false;
+  auto basicBlocks = func->getBasicBlocks();
+  for (auto &block : basicBlocks) {
+    if (block->getNumSuccessors() == 0) {
+      changed = true;
+      // 如果基本块没有后继块，则添加一个返回指令
+      if (block->getNumInstructions() == 0) {
+        pBuilder->setPosition(block.get(), block->end());
+        pBuilder->createReturnInst();
+      }
+      auto thelastinst = block->getInstructions().end();
+      --thelastinst;
+      if (thelastinst->get()->getKind() != Instruction::kReturn) {
+        // std::cout << "Warning: Function " << func->getName() << " has no return instruction, adding default return." << std::endl;
 
-          pBuilder->setPosition(block.get(), block->end());
-          // TODO: 如果int float函数缺少返回值是否需要报错
-          if (func->getReturnType()->isInt()) {
-            pBuilder->createReturnInst(ConstantValue::get(0));
-          } else if (func->getReturnType()->isFloat()) {
-            pBuilder->createReturnInst(ConstantValue::get(0.0F));
-          } else {
-            pBuilder->createReturnInst();
-          }
+        pBuilder->setPosition(block.get(), block->end());
+        // TODO: 如果int float函数缺少返回值是否需要报错
+        if (func->getReturnType()->isInt()) {
+          pBuilder->createReturnInst(ConstantValue::get(0));
+        } else if (func->getReturnType()->isFloat()) {
+          pBuilder->createReturnInst(ConstantValue::get(0.0F));
+        } else {
+          pBuilder->createReturnInst();
         }
       }
     }
   }
+  
+  return changed;
 }
 
 }  // namespace sysy

src/include/SysYIRCFGOpt.h

@@ -26,18 +26,32 @@ class SysYCFGOpt {
   SysYCFGOpt(Module *pMoudle, IRBuilder *pBuilder) : pModule(pMoudle), pBuilder(pBuilder) {}
 
   void SysYOptimizateAfterIR(){
-    SysYDelInstAfterBr();
-    SysYBlockMerge();
-    SysYDelNoPreBLock();
-    SysYDelEmptyBlock();
-    SysYAddReturn();
+    
+    auto &functions = pModule->getFunctions();
+    for (auto &function : functions) {
+      bool changed = false;
+      while(changed){
+        // 删除br后面的无用指令
+        changed |= SysYDelInstAfterBr(function.second.get());
+        // 合并空基本块
+        changed |= SysYBlockMerge(function.second.get());
+        // 删除无前驱块
+        changed |= SysYDelNoPreBLock(function.second.get());
+        // 删除空块
+        changed |= SysYDelEmptyBlock(function.second.get(), pBuilder);
+        // 添加return指令
+        changed |= SysYAddReturn(function.second.get(), pBuilder);
+      }
+    }
   }
-  void SysYDelInstAfterBr(); // 删除br后面的指令
-  void SysYDelEmptyBlock(); // 空块删除
-  void SysYDelNoPreBLock(); // 删除无前驱块（不可达块）
-  void SysYBlockMerge();    // 合并基本块(主要针对嵌套if while的exit块，
+
+public:
+  static bool SysYDelInstAfterBr(Function *func); // 删除br后面的指令
+  static bool SysYDelEmptyBlock(Function *func, IRBuilder* pBuilder); // 空块删除
+  static bool SysYDelNoPreBLock(Function *func); // 删除无前驱块（不可达块）
+  static bool SysYBlockMerge(Function *func);    // 合并基本块(主要针对嵌套if while的exit块，
                             // 也可以修改IR生成实现回填机制
-  void SysYAddReturn();     // 添加return指令(主要针对Void函数)
+  static bool SysYAddReturn(Function *func, IRBuilder* pBuilder);     // 添加return指令(主要针对Void函数)
 };
 
 }  // namespace sysy