Files
mysysy/src/midend/Pass/Optimize/LargeArrayToGlobal.cpp
2025-08-10 17:32:45 +08:00

145 lines
4.8 KiB
C++

#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);
if(DEBUG){
// 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) {
if(DEBUG)
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