添加数据流分析类，实现前向后向分析的模板动作，实现活跃变量分析，基本借鉴学长代码，后续可优化实现
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rain2133
@@ -254,6 +254,267 @@ void ControlFlowAnalysis::computeDomFrontierAllBlk() {
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}
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}
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// ==========================
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// dataflow analysis utils
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// ==========================
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// 先引用学长的代码
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// TODO: Worklist 增加逆后序遍历机制
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void DataFlowAnalysisUtils::forwardAnalyze(Module *pModule){
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std::map<DataFlowAnalysis *, bool> workAnalysis;
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for (auto &dataflow : forwardAnalysisList) {
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dataflow->init(pModule);
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}
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for (const auto &function : pModule->getFunctions()) {
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for (auto &dataflow : forwardAnalysisList) {
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workAnalysis.emplace(dataflow, false);
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}
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while (!workAnalysis.empty()) {
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for (const auto &block : function.second->getBasicBlocks()) {
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for (auto &elem : workAnalysis) {
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if (elem.first->analyze(pModule, block.get())) {
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elem.second = true;
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}
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}
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}
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std::map<DataFlowAnalysis *, bool> tmp;
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std::remove_copy_if(workAnalysis.begin(), workAnalysis.end(), std::inserter(tmp, tmp.end()),
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[](const std::pair<DataFlowAnalysis *, bool> &elem) -> bool { return !elem.second; });
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workAnalysis.swap(tmp);
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for (auto &elem : workAnalysis) {
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elem.second = false;
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}
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}
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}
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}
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void DataFlowAnalysisUtils::backwardAnalyze(Module *pModule) {
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std::map<DataFlowAnalysis *, bool> workAnalysis;
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for (auto &dataflow : backwardAnalysisList) {
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dataflow->init(pModule);
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}
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for (const auto &function : pModule->getFunctions()) {
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for (auto &dataflow : backwardAnalysisList) {
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workAnalysis.emplace(dataflow, false);
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}
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while (!workAnalysis.empty()) {
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for (const auto &block : function.second->getBasicBlocks()) {
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for (auto &elem : workAnalysis) {
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if (elem.first->analyze(pModule, block.get())) {
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elem.second = true;
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}
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}
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}
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std::map<DataFlowAnalysis *, bool> tmp;
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std::remove_copy_if(workAnalysis.begin(), workAnalysis.end(), std::inserter(tmp, tmp.end()),
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[](const std::pair<DataFlowAnalysis *, bool> &elem) -> bool { return !elem.second; });
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workAnalysis.swap(tmp);
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for (auto &elem : workAnalysis) {
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elem.second = false;
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}
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}
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}
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}
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std::set<User *> ActiveVarAnalysis::getUsedSet(Instruction *inst) {
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using Kind = Instruction::Kind;
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std::vector<User *> operands;
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for (const auto &operand : inst->getOperands()) {
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operands.emplace_back(dynamic_cast<User *>(operand->getValue()));
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}
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std::set<User *> result;
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switch (inst->getKind()) {
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// phi op
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case Kind::kPhi:
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case Kind::kCall:
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result.insert(std::next(operands.begin()), operands.end());
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break;
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case Kind::kCondBr:
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result.insert(operands[0]);
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break;
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case Kind::kBr:
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case Kind::kAlloca:
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break;
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// mem op
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case Kind::kStore:
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// StoreInst 的第一个操作数是被存储的值，第二个操作数是存储的变量
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// 后续的是可能的数组维度
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result.insert(operands[0]);
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result.insert(operands.begin() + 2, operands.end());
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break;
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case Kind::kLoad:
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case Kind::kLa: {
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auto variable = dynamic_cast<AllocaInst *>(operands[0]);
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auto global = dynamic_cast<GlobalValue *>(operands[0]);
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auto constArray = dynamic_cast<ConstantVariable *>(operands[0]);
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if ((variable != nullptr && variable->getNumDims() == 0) || (global != nullptr && global->getNumDims() == 0) ||
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(constArray != nullptr && constArray->getNumDims() == 0)) {
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result.insert(operands[0]);
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}
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result.insert(std::next(operands.begin()), operands.end());
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break;
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}
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case Kind::kGetSubArray: {
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for (unsigned i = 2; i < operands.size(); i++) {
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// 数组的维度信息
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result.insert(operands[i]);
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}
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break;
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}
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case Kind::kMemset: {
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result.insert(std::next(operands.begin()), operands.end());
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break;
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}
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case Kind::kInvalid:
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// Binary
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case Kind::kAdd:
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case Kind::kSub:
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case Kind::kMul:
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case Kind::kDiv:
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case Kind::kRem:
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case Kind::kICmpEQ:
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case Kind::kICmpNE:
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case Kind::kICmpLT:
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case Kind::kICmpLE:
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case Kind::kICmpGT:
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case Kind::kICmpGE:
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case Kind::kFAdd:
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case Kind::kFSub:
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case Kind::kFMul:
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case Kind::kFDiv:
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case Kind::kFCmpEQ:
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case Kind::kFCmpNE:
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case Kind::kFCmpLT:
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case Kind::kFCmpLE:
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case Kind::kFCmpGT:
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case Kind::kFCmpGE:
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case Kind::kAnd:
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case Kind::kOr:
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// Unary
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case Kind::kNeg:
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case Kind::kNot:
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case Kind::kFNot:
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case Kind::kFNeg:
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case Kind::kFtoI:
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case Kind::kItoF:
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// terminator
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case Kind::kReturn:
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result.insert(operands.begin(), operands.end());
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break;
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default:
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assert(false);
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break;
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}
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result.erase(nullptr);
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return result;
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}
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User * ActiveVarAnalysis::getDefine(Instruction *inst) {
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User *result = nullptr;
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if (inst->isStore()) {
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StoreInst* store = dynamic_cast<StoreInst *>(inst);
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auto operand = store->getPointer();
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AllocaInst* variable = dynamic_cast<AllocaInst *>(operand);
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GlobalValue* global = dynamic_cast<GlobalValue *>(operand);
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if ((variable != nullptr && variable->getNumDims() != 0) || (global != nullptr && global->getNumDims() != 0)) {
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// 如果是数组变量或者全局变量，则不返回定义
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// TODO：兼容数组变量
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result = nullptr;
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} else {
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result = dynamic_cast<User *>(operand);
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}
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} else if (inst->isPhi()) {
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result = dynamic_cast<User *>(inst->getOperand(0));
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} else if (inst->isBinary() || inst->isUnary() || inst->isCall() ||
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inst->isLoad() || inst->isLa()) {
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result = dynamic_cast<User *>(inst);
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}
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return result;
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}
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void ActiveVarAnalysis::init(Module *pModule) {
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for (const auto &function : pModule->getFunctions()) {
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for (const auto &block : function.second->getBasicBlocks()) {
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activeTable.emplace(block.get(), std::vector<std::set<User *>>{});
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for (unsigned i = 0; i < block->getNumInstructions() + 1; i++)
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activeTable.at(block.get()).emplace_back();
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}
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}
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}
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// 活跃变量分析公式 每个块内的分析动作供分析器调用
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bool ActiveVarAnalysis::analyze(Module *pModule, BasicBlock *block) {
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bool changed = false; // 标记数据流结果是否有变化
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std::set<User *> activeSet{}; // 当前计算的活跃变量集合
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// 步骤1: 计算基本块出口的活跃变量集 (OUT[B])
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// 公式: OUT[B] = ∪_{S ∈ succ(B)} IN[S]
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for (const auto &succ : block->getSuccessors()) {
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// 获取后继块入口的活跃变量集 (IN[S])
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auto succActiveSet = activeTable.at(succ).front();
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// 合并所有后继块的入口活跃变量
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activeSet.insert(succActiveSet.begin(), succActiveSet.end());
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}
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// 步骤2: 处理基本块出口处的活跃变量集
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const auto &instructions = block->getInstructions();
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const auto numInstructions = instructions.size();
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// 获取旧的出口活跃变量集 (block出口对应索引numInstructions)
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const auto &oldEndActiveSet = activeTable.at(block)[numInstructions];
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// 检查出口活跃变量集是否有变化
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if (!std::equal(activeSet.begin(), activeSet.end(),
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oldEndActiveSet.begin(), oldEndActiveSet.end()))
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{
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changed = true; // 标记变化
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activeTable.at(block)[numInstructions] = activeSet; // 更新出口活跃变量集
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}
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// 步骤3: 逆序遍历基本块中的指令
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// 从最后一条指令开始向前计算每个程序点的活跃变量
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auto instructionIter = instructions.end();
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instructionIter--; // 指向最后一条指令
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// 从出口向入口遍历 (索引从numInstructions递减到1)
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for (unsigned i = numInstructions; i > 0; i--) {
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auto inst = instructionIter->get(); // 当前指令
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auto used = getUsedSet(inst);
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User *defined = getDefine(inst);
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// 步骤3.3: 计算指令入口的活跃变量 (IN[i])
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// 公式: IN[i] = use_i ∪ (OUT[i] - def_i)
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activeSet.erase(defined); // 移除被定义的变量 (OUT[i] - def_i)
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activeSet.insert(used.begin(), used.end()); // 添加使用的变量
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// 获取旧的入口活跃变量集 (位置i-1对应当前指令的入口)
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const auto &oldActiveSet = activeTable.at(block)[i - 1];
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// 检查活跃变量集是否有变化
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if (!std::equal(activeSet.begin(), activeSet.end(),
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oldActiveSet.begin(), oldActiveSet.end()))
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{
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changed = true; // 标记变化
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activeTable.at(block)[i - 1] = activeSet; // 更新入口活跃变量集
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}
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instructionIter--; // 移动到前一条指令
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}
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return changed; // 返回数据流结果是否变化
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}
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auto ActiveVarAnalysis::getActiveTable() const -> const std::map<BasicBlock *, std::vector<std::set<User *>>> & {
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return activeTable;
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}
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} // namespace sysy
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