[backend-LAG]添加新的LargeArrayToGlobal中端Pass，以及栈保护逻辑

src/backend/RISCv64/Handler/EliminateFrameIndices.cpp

@@ -46,9 +46,13 @@ void EliminateFrameIndicesPass::runOnMachineFunction(MachineFunction* mfunc) {
                     Type* allocated_type = alloca->getType()->as<PointerType>()->getBaseType();
                     int size = getTypeSizeInBytes(allocated_type);
                     
-                    // RISC-V要求栈地址8字节对齐
+                    // 优化栈帧大小：对于大数组使用4字节对齐，小对象使用8字节对齐
-                    size = (size + 7) & ~7;
+                    if (size >= 256) {  // 大数组优化
-                    if (size == 0) size = 8; // 至少分配8字节
+                        size = (size + 3) & ~3;  // 4字节对齐
+                    } else {
+                        size = (size + 7) & ~7;  // 8字节对齐
+                    }
+                    if (size == 0) size = 4; // 最小4字节
 
                     local_var_offset += size;
                     unsigned alloca_vreg = isel->getVReg(alloca);

src/backend/RISCv64/Handler/PrologueEpilogueInsertion.cpp

@@ -47,12 +47,22 @@ void PrologueEpilogueInsertionPass::runOnMachineFunction(MachineFunction* mfunc)
     std::sort(frame_info.callee_saved_regs_to_store.begin(), frame_info.callee_saved_regs_to_store.end());
     frame_info.callee_saved_size = frame_info.callee_saved_regs_to_store.size() * 8;
 
-    // 3. 计算最终的栈帧总大小
+    // 3. 计算最终的栈帧总大小，包含栈溢出保护
     int total_stack_size = frame_info.locals_size + 
                            frame_info.spill_size + 
                            frame_info.callee_saved_size + 
                            16;
     
+    // 栈溢出保护：增加最大栈帧大小以容纳大型数组
+    const int MAX_STACK_FRAME_SIZE = 8192; // 8KB to handle large arrays like 256*4*2 = 2048 bytes
+    if (total_stack_size > MAX_STACK_FRAME_SIZE) {
+        // 如果仍然超过限制，尝试优化对齐方式
+        std::cerr << "Warning: Stack frame size " << total_stack_size 
+                  << " exceeds recommended limit " << MAX_STACK_FRAME_SIZE << " for function " 
+                  << mfunc->getName() << std::endl;
+    }
+    
+    // 优化：减少对齐开销，使用16字节对齐而非更大的对齐
     int aligned_stack_size = (total_stack_size + 15) & ~15;
     frame_info.total_size = aligned_stack_size;
 

src/backend/RISCv64/RISCv64ISel.cpp

@@ -1289,14 +1289,19 @@ void RISCv64ISel::selectNode(DAGNode* node) {
                 if (stride != 0) {
                     // --- 为当前索引和步长生成偏移计算指令 ---
                     auto offset_vreg = getNewVReg();
-                    auto index_vreg = getVReg(indexValue);
+                    
-
+                    // 处理索引 - 区分常量与动态值
-                    // 如果索引是常量，先用 LI 指令加载到虚拟寄存器
+                    unsigned index_vreg;
                     if (auto const_index = dynamic_cast<ConstantValue*>(indexValue)) {
+                        // 对于常量索引，直接创建新的虚拟寄存器
+                        index_vreg = getNewVReg();
                         auto li = std::make_unique<MachineInstr>(RVOpcodes::LI);
                         li->addOperand(std::make_unique<RegOperand>(index_vreg));
                         li->addOperand(std::make_unique<ImmOperand>(const_index->getInt()));
                         CurMBB->addInstruction(std::move(li));
+                    } else {
+                        // 对于动态索引，使用已存在的虚拟寄存器
+                        index_vreg = getVReg(indexValue);
                     }
                     
                     // 优化：如果步长是1，可以直接移动(MV)作为偏移量，无需乘法

src/include/midend/Pass/Optimize/LargeArrayToGlobal.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include "../Pass.h"
+
+namespace sysy {
+
+class LargeArrayToGlobalPass : public OptimizationPass {
+public:
+    static void *ID;
+
+    LargeArrayToGlobalPass() : OptimizationPass("LargeArrayToGlobal", Granularity::Module) {}
+
+    bool runOnModule(Module *M, AnalysisManager &AM) override;
+    void *getPassID() const override {
+        return &ID;
+    }
+
+private:
+    unsigned calculateTypeSize(Type *type);
+    void convertAllocaToGlobal(AllocaInst *alloca, Function *F, Module *M);
+    std::string generateUniqueGlobalName(AllocaInst *alloca, Function *F);
+};
+
+} // namespace sysy

src/include/midend/Pass/Pass.h

@@ -279,7 +279,7 @@ private:
   IRBuilder *pBuilder;
 
 public:
-  PassManager() = default;
+  PassManager() = delete;
   ~PassManager() = default;
 
   PassManager(Module *module, IRBuilder *builder) : pmodule(module) ,pBuilder(builder), analysisManager(module) {}

src/midend/CMakeLists.txt

@@ -12,6 +12,7 @@ add_library(midend_lib STATIC
     Pass/Optimize/SysYIRCFGOpt.cpp
     Pass/Optimize/SCCP.cpp
     Pass/Optimize/BuildCFG.cpp
+    Pass/Optimize/LargeArrayToGlobal.cpp
 )
 
 # 包含中端模块所需的头文件路径

src/midend/Pass/Optimize/LargeArrayToGlobal.cpp

@@ -0,0 +1,143 @@
+#include "../../include/midend/Pass/Optimize/LargeArrayToGlobal.h"
+#include "../../IR.h"
+#include <unordered_map>
+#include <sstream>
+#include <string>
+
+namespace sysy {
+
+// Helper function to convert type to string
+static std::string typeToString(Type *type) {
+    if (!type) return "null";
+    
+    switch (type->getKind()) {
+        case Type::kInt:
+            return "int";
+        case Type::kFloat:
+            return "float";
+        case Type::kPointer:
+            return "ptr";
+        case Type::kArray: {
+            auto *arrayType = type->as<ArrayType>();
+            return "[" + std::to_string(arrayType->getNumElements()) + " x " + 
+                   typeToString(arrayType->getElementType()) + "]";
+        }
+        default:
+            return "unknown";
+    }
+}
+
+void *LargeArrayToGlobalPass::ID = &LargeArrayToGlobalPass::ID;
+
+bool LargeArrayToGlobalPass::runOnModule(Module *M, AnalysisManager &AM) {
+        bool changed = false;
+        
+        if (!M) {
+            return false;
+        }
+
+        // Collect all alloca instructions from all functions
+        std::vector<std::pair<AllocaInst*, Function*>> allocasToConvert;
+        
+        for (auto &funcPair : M->getFunctions()) {
+            Function *F = funcPair.second.get();
+            if (!F || F->getBasicBlocks().begin() == F->getBasicBlocks().end()) {
+                continue;
+            }
+            
+            for (auto &BB : F->getBasicBlocks()) {
+                for (auto &inst : BB->getInstructions()) {
+                    if (auto *alloca = dynamic_cast<AllocaInst*>(inst.get())) {
+                        Type *allocatedType = alloca->getAllocatedType();
+                        
+                        // Calculate the size of the allocated type
+                        unsigned size = calculateTypeSize(allocatedType);
+                        
+                        // Debug: print size information
+                        std::cout << "LargeArrayToGlobalPass: Found alloca with size " << size 
+                                  << " for type " << typeToString(allocatedType) << std::endl;
+                        
+                        // Convert arrays of 1KB (1024 bytes) or larger to global variables
+                        if (size >= 1024) {
+                            std::cout << "LargeArrayToGlobalPass: Converting array of size " << size << " to global" << std::endl;
+                            allocasToConvert.emplace_back(alloca, F);
+                        }
+                    }
+                }
+            }
+        }
+
+        // Convert the collected alloca instructions to global variables
+        for (auto [alloca, F] : allocasToConvert) {
+            convertAllocaToGlobal(alloca, F, M);
+            changed = true;
+        }
+
+return changed;
+    }
+
+unsigned LargeArrayToGlobalPass::calculateTypeSize(Type *type) {
+    if (!type) return 0;
+
+    switch (type->getKind()) {
+        case Type::kInt:
+        case Type::kFloat:
+            return 4;
+        case Type::kPointer:
+            return 8;
+        case Type::kArray: {
+            auto *arrayType = type->as<ArrayType>();
+            return arrayType->getNumElements() * calculateTypeSize(arrayType->getElementType());
+        }
+        default:
+            return 0;
+    }
+}
+
+void LargeArrayToGlobalPass::convertAllocaToGlobal(AllocaInst *alloca, Function *F, Module *M) {
+    Type *allocatedType = alloca->getAllocatedType();
+    
+    // Create a unique name for the global variable
+    std::string globalName = generateUniqueGlobalName(alloca, F);
+    
+    // Create the global variable - GlobalValue expects pointer type
+    Type *pointerType = Type::getPointerType(allocatedType);
+    GlobalValue *globalVar = M->createGlobalValue(globalName, pointerType);
+    
+    if (!globalVar) {
+        return;
+    }
+    
+    // Replace all uses of the alloca with the global variable
+    alloca->replaceAllUsesWith(globalVar);
+    
+    // Remove the alloca instruction from its basic block
+    for (auto &BB : F->getBasicBlocks()) {
+        auto &instructions = BB->getInstructions();
+        for (auto it = instructions.begin(); it != instructions.end(); ++it) {
+            if (it->get() == alloca) {
+                instructions.erase(it);
+                break;
+            }
+        }
+    }
+}
+
+std::string LargeArrayToGlobalPass::generateUniqueGlobalName(AllocaInst *alloca, Function *F) {
+    std::string baseName = alloca->getName();
+    if (baseName.empty()) {
+        baseName = "array";
+    }
+    
+    // Ensure uniqueness by appending function name and counter
+    static std::unordered_map<std::string, int> nameCounter;
+    std::string key = F->getName() + "." + baseName;
+    
+    int counter = nameCounter[key]++;
+    std::ostringstream oss;
+    oss << key << "." << counter;
+    
+    return oss.str();
+}
+
+} // namespace sysy

src/midend/Pass/Pass.cpp

@@ -7,6 +7,7 @@
 #include "Reg2Mem.h"
 #include "SCCP.h"
 #include "BuildCFG.h"
+#include "LargeArrayToGlobal.h"
 #include "Pass.h"
 #include <iostream>
 #include <queue>
@@ -41,6 +42,7 @@ void PassManager::runOptimizationPipeline(Module* moduleIR, IRBuilder* builderIR
 
     // 注册优化遍
     registerOptimizationPass<BuildCFG>();
+    registerOptimizationPass<LargeArrayToGlobalPass>();
     
     registerOptimizationPass<SysYDelInstAfterBrPass>();
     registerOptimizationPass<SysYDelNoPreBLockPass>();
@@ -68,6 +70,7 @@ void PassManager::runOptimizationPipeline(Module* moduleIR, IRBuilder* builderIR
 
       this->clearPasses();
       this->addPass(&BuildCFG::ID);
+      this->addPass(&LargeArrayToGlobalPass::ID);
       this->run();
 
       this->clearPasses();