[CFG]CFG优化方法转换为静态方法，方便其他优化遍调用，TODO：简化条件分支

src/SysYIRCFGOpt.cpp

@@ -13,10 +13,10 @@ namespace sysy {
 
 
 // 删除br后的无用指令
-void SysYCFGOpt::SysYDelInstAfterBr() {
+bool SysYCFGOpt::SysYDelInstAfterBr(Function *func) {
-  auto &functions = pModule->getFunctions();
+  bool changed = false;
-  for (auto &function : functions) {
+  
-    auto basicBlocks = function.second->getBasicBlocks();
+  auto basicBlocks = func->getBasicBlocks();
   for (auto &basicBlock : basicBlocks) {
     bool Branch = false;
     auto &instructions = basicBlock->getInstructions();
@@ -30,8 +30,10 @@ void SysYCFGOpt::SysYDelInstAfterBr() {
       }
     }
     if (Branchiter != instructions.end()) ++Branchiter;
-      while (Branchiter != instructions.end()) 
+    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();
@@ -55,15 +57,14 @@ void SysYCFGOpt::SysYDelInstAfterBr() {
       }
     }
   }
-  }
+
+  return changed;
 }
 
 // 合并空基本块
-void SysYCFGOpt::SysYBlockMerge() {
+bool SysYCFGOpt::SysYBlockMerge(Function *func) {
-  auto &functions = pModule->getFunctions(); //std::map<std::string, std::unique_ptr<Function>>
+  bool changed = false;
-  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) {
@@ -117,6 +118,7 @@ void SysYCFGOpt::SysYBlockMerge() {
         }
 
         func->removeBasicBlock(nextBlock);
+        changed = true;
 
       } else {
         blockiter++;
@@ -125,15 +127,14 @@ void SysYCFGOpt::SysYBlockMerge() {
       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>>
+  bool changed = false;
-  for (auto &function : functions) {
-    auto &func = function.second;
 
   for (auto &block : func->getBasicBlocks()) {
     block->setreachableFalse();
@@ -156,7 +157,6 @@ void SysYCFGOpt::SysYDelNoPreBLock() {
 
   // 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());
@@ -183,20 +183,23 @@ void SysYCFGOpt::SysYDelNoPreBLock() {
       }
       // 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;
 }
 
-void SysYCFGOpt::SysYDelEmptyBlock() {
+// 删除空块
-  auto &functions = pModule->getFunctions();
+bool SysYCFGOpt::SysYDelEmptyBlock(Function *func, IRBuilder* pBuilder) {
-  for (auto &function : functions) {
+  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 = function.second->getBasicBlocks();
+  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) {
@@ -399,11 +402,11 @@ void SysYCFGOpt::SysYDelEmptyBlock() {
     }
   }
 
-    for (auto iter = function.second->getBasicBlocks().begin(); iter != function.second->getBasicBlocks().end();) {
+  for (auto iter = func->getBasicBlocks().begin(); iter != func->getBasicBlocks().end();) {
     
     if (EmptyBlocks.find(iter->get()) != EmptyBlocks.end()) {
       // EntryBlock跳过
-        if (iter->get() == function.second->getEntryBlock()) {
+      if (iter->get() == func->getEntryBlock()) {
         ++iter;
         continue;
       }
@@ -429,22 +432,24 @@ void SysYCFGOpt::SysYDelEmptyBlock() {
         }
       }
 
-        function.second->removeBasicBlock((iter++)->get());
+      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() {
+bool SysYCFGOpt::SysYAddReturn(Function *func, IRBuilder* pBuilder) {
-  auto &functions = pModule->getFunctions();
+  bool changed = false;
-  for (auto &function : functions) {
-    auto &func = function.second;
   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());
@@ -467,7 +472,8 @@ void SysYCFGOpt::SysYAddReturn() {
       }
     }
   }
-  }
+  
+  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();
+    auto &functions = pModule->getFunctions();
-    SysYDelNoPreBLock();
+    for (auto &function : functions) {
-    SysYDelEmptyBlock();
+      bool changed = false;
-    SysYAddReturn();
+      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