IRoptpre 初步构建

src/SysYIROptPre.cpp

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+/**
+ * @file: Sysyoptimization.cpp
+ * @brief  CFG优化
+ * @Author : Ixeux email:you@domain.com
+ * @Version : 1.0
+ * @Creat Date : 2024-08-10
+ *
+ */
+#include "SysYIROptPre.h"
+#include <cassert>
+#include <list>
+#include <map>
+#include <memory>
+#include <string>
+#include "IR.h"
+#include "IRBuilder.h"
+
+namespace sysy {
+
+void SysYOptPre::SysYOptimizateAll() -> void {
+  SysYDelAfterBr();
+  SysYBlockMerge();
+  SysYDelNoPreBLock();
+  SysYDelEmptyBlock();
+  SysYAddReturn();
+}
+
+/**
+ * use删除operand,以免扰乱后续分析
+ * instr: 要删除的指令
+ */
+void SysYOptPre::usedelete(Instruction *instr) {
+  for (auto &use : instr->getOperands()) {
+    Value* val = use->getValue();
+    // std::cout << delete << val->getName() << std::endl;
+    val->removeUse(use);
+  }
+}
+
+
+// 删除br后的无用指令
+void SysYOptPre::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 iter = instructions.begin();
+      auto Branchiter = instructions.end();
+      for (auto iter = instructions->begin(); iter != instructions->end();iter++) {
+        if (Branch) 
+          usedelete(iter->get());
+        else if ((*iter)->isTerminator()){
+          Branch = true;
+          Branchiter = iter;
+        }
+      }
+      Branchiter++;
+      while(Branchiter != instructions->begin()) 
+        Branchiter = instructions.erase(Branchiter);
+      
+      if (Branch) {  // 更新前驱后继关系
+        auto thelastinst = basicBlock->getInstructions().end();
+        --thelastinst;
+        auto &Successors = basicBlock->getSuccessors();
+        for (auto iterSucc = Successors.begin(); iterSucc != Successors.end();) {
+          (*iterSucc)->removePredecessor(basicBlock.get());
+          basicBlock->removeSuccessor(*iterSucc);
+        }
+        if (thelastinst->get()->isUnconditional()) {
+          BasicBlock* branchBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0));
+          basicBlock->addSuccessor(branchBlock);
+          branchBlock->addPredecessor(basicBlock.get());
+        } else if (thelastinst->get()->isConditional()) {
+          BasicBlock* thenBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1));
+          BasicBlock* elseBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2));
+          basicBlock->addSuccessor(thenBlock);
+          basicBlock->addSuccessor(elseBlock);
+          thenBlock->addPredecessor(basicBlock.get());
+          elseBlock->addPredecessor(basicBlock.get());
+        }
+      }
+    }
+  }
+}
+
+
+void SysYOptPre::SysYBlockMerge() {
+  auto &functions = pModule->getFunctions(); //std::map<std::string, std::unique_ptr<Function>>
+  for (auto &function : functions) {
+    // auto basicBlocks = function.second->getBasicBlocks();
+    Function* func = function.second.get();
+    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 thelastinst = block->end();
+            (--thelastinst);
+            if (thelastinst->get()->isUnconditional()) {
+              usedelete(thelastinst->get());
+              block->getInstructions().erase(thelastinst);
+            } else if (thelastinst->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 (thelastinst->get()->getOperand(1)->getName() == thelastinst->get()->getOperand(1)->getName()) {
+                usedelete(thelastinst->get());
+                block->getInstructions().erase(thelastinst);
+              }
+            }
+          }
+          // 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
+          for (auto &argm : nextarguments) {
+            argm->setParent(block);
+            block->insertArgument(argm);
+          }
+          // // // 改变block 和 next 之间的关系
+          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);
+          }
+
+          // // // 添加block 和 next 的后继 之间的关系
+          // block->addSuccessor(nextBlock->getSuccessors()[0]);
+          // nextBlock->getSuccessors()[0]->addPredecessor(blockiter->get());
+          // // // 删除next 和 next后继的关系
+          // nextBlock->getSuccessors()[0]->removePredecessor(nextBlock);
+          // nextBlock->removeSuccessor(nextBlock->getSuccessors()[0]);
+          // std::cout << nextBlock->getName() << std::endl;
+
+          function.second->removeBasicBlock(nextBlock);
+          // ++blockiter;
+        } else {
+          blockiter++;
+        }
+      } else {
+        blockiter++;
+      }
+    }
+  }
+}
+
+
+void SysYOptPre::SysYDelNoPreBLock() {
+}
+
+
+void SysYOptPre::SysYAddReturn() {
+}
+
+}  // namespace sysy