282 lines
10 KiB
C++
282 lines
10 KiB
C++
#include "RISCv64Backend.h"
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#include "RISCv64ISel.h"
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#include "RISCv64RegAlloc.h"
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#include "RISCv64AsmPrinter.h"
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#include "RISCv64Passes.h"
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#include <sstream>
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namespace sysy {
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// 顶层入口
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std::string RISCv64CodeGen::code_gen() {
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return module_gen();
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}
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unsigned RISCv64CodeGen::getTypeSizeInBytes(Type* type) {
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if (!type) {
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assert(false && "Cannot get size of a null type.");
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return 0;
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}
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switch (type->getKind()) {
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// 对于SysY语言，基本类型int和float都占用4字节
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case Type::kInt:
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case Type::kFloat:
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return 4;
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// 指针类型在RISC-V 64位架构下占用8字节
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// 虽然SysY没有'int*'语法，但数组变量在IR层面本身就是指针类型
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case Type::kPointer:
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return 8;
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// 数组类型的总大小 = 元素数量 * 单个元素的大小
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case Type::kArray: {
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auto arrayType = type->as<ArrayType>();
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// 递归调用以计算元素大小
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return arrayType->getNumElements() * getTypeSizeInBytes(arrayType->getElementType());
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}
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// 其他类型，如Void, Label等不占用栈空间，或者不应该出现在这里
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default:
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// 如果遇到未处理的类型，触发断言，方便调试
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// assert(false && "Unsupported type for size calculation.");
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return 0; // 对于像Label或Void这样的类型，返回0是合理的
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}
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}
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void printInitializer(std::stringstream& ss, const ValueCounter& init_values) {
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for (size_t i = 0; i < init_values.getValues().size(); ++i) {
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auto val = init_values.getValues()[i];
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auto count = init_values.getNumbers()[i];
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if (auto constant = dynamic_cast<ConstantValue*>(val)) {
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for (unsigned j = 0; j < count; ++j) {
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if (constant->isInt()) {
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ss << " .word " << constant->getInt() << "\n";
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} else {
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float f = constant->getFloat();
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uint32_t float_bits = *(uint32_t*)&f;
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ss << " .word " << float_bits << "\n";
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}
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}
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}
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}
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}
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std::string RISCv64CodeGen::module_gen() {
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std::stringstream ss;
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// --- 步骤1：将全局变量(GlobalValue)分为.data和.bss两组 ---
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std::vector<GlobalValue*> data_globals;
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std::vector<GlobalValue*> bss_globals;
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for (const auto& global_ptr : module->getGlobals()) {
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GlobalValue* global = global_ptr.get();
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// 使用更健壮的逻辑来判断是否为大型零初始化数组
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bool is_all_zeros = true;
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const auto& init_values = global->getInitValues();
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// 检查初始化值是否全部为0
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if (init_values.getValues().empty()) {
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// 如果 ValueCounter 为空，GlobalValue 的构造函数会确保它是零初始化的
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is_all_zeros = true;
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} else {
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for (auto val : init_values.getValues()) {
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if (auto const_val = dynamic_cast<ConstantValue*>(val)) {
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if (!const_val->isZero()) {
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is_all_zeros = false;
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break;
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}
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} else {
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// 如果初始值包含非常量（例如，另一个全局变量的地址），则不认为是纯零初始化
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is_all_zeros = false;
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break;
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}
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}
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}
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// 使用 getTypeSizeInBytes 检查总大小是否超过阈值 (16个整数 = 64字节)
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Type* allocated_type = global->getType()->as<PointerType>()->getBaseType();
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unsigned total_size = getTypeSizeInBytes(allocated_type);
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bool is_large_zero_array = is_all_zeros && (total_size > 64);
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if (is_large_zero_array) {
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bss_globals.push_back(global);
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} else {
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data_globals.push_back(global);
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}
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}
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// --- 步骤2：生成 .bss 段的代码 ---
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if (!bss_globals.empty()) {
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ss << ".bss\n";
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for (GlobalValue* global : bss_globals) {
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Type* allocated_type = global->getType()->as<PointerType>()->getBaseType();
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unsigned total_size = getTypeSizeInBytes(allocated_type);
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ss << " .align 3\n";
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ss << ".globl " << global->getName() << "\n";
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ss << ".type " << global->getName() << ", @object\n";
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ss << ".size " << global->getName() << ", " << total_size << "\n";
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ss << global->getName() << ":\n";
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ss << " .space " << total_size << "\n";
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}
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}
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// --- 步骤3：生成 .data 段的代码 ---
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if (!data_globals.empty() || !module->getConsts().empty()) {
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ss << ".data\n";
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// a. 处理普通的全局变量 (GlobalValue)
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for (GlobalValue* global : data_globals) {
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Type* allocated_type = global->getType()->as<PointerType>()->getBaseType();
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unsigned total_size = getTypeSizeInBytes(allocated_type);
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ss << " .align 3\n";
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ss << ".globl " << global->getName() << "\n";
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ss << ".type " << global->getName() << ", @object\n";
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ss << ".size " << global->getName() << ", " << total_size << "\n";
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ss << global->getName() << ":\n";
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bool is_all_zeros = true;
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const auto& init_values = global->getInitValues();
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if (init_values.getValues().empty()) {
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is_all_zeros = true;
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} else {
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for (auto val : init_values.getValues()) {
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if (auto const_val = dynamic_cast<ConstantValue*>(val)) {
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if (!const_val->isZero()) {
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is_all_zeros = false;
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break;
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}
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} else {
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is_all_zeros = false;
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break;
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}
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}
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}
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if (is_all_zeros) {
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ss << " .zero " << total_size << "\n";
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} else {
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// 对于有非零初始值的变量，保持原有的打印逻辑。
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printInitializer(ss, global->getInitValues());
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}
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}
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// b. 处理全局常量 (ConstantVariable)
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for (const auto& const_ptr : module->getConsts()) {
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ConstantVariable* cnst = const_ptr.get();
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Type* allocated_type = cnst->getType()->as<PointerType>()->getBaseType();
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unsigned total_size = getTypeSizeInBytes(allocated_type);
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ss << " .align 3\n";
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ss << ".globl " << cnst->getName() << "\n";
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ss << ".type " << cnst->getName() << ", @object\n";
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ss << ".size " << cnst->getName() << ", " << total_size << "\n";
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ss << cnst->getName() << ":\n";
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printInitializer(ss, cnst->getInitValues());
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}
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}
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// --- 步骤4：处理函数 (.text段) 的逻辑 ---
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if (!module->getFunctions().empty()) {
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ss << ".text\n";
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for (const auto& func_pair : module->getFunctions()) {
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if (func_pair.second.get() && !func_pair.second->getBasicBlocks().empty()) {
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ss << function_gen(func_pair.second.get());
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if (DEBUG) std::cerr << "Function: " << func_pair.first << " generated.\n";
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}
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}
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}
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return ss.str();
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}
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std::string RISCv64CodeGen::function_gen(Function* func) {
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// === 完整的后端处理流水线 ===
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// 阶段 1: 指令选择 (sysy::IR -> LLIR with virtual registers)
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DEBUG = 0;
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DEEPDEBUG = 0;
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RISCv64ISel isel;
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std::unique_ptr<MachineFunction> mfunc = isel.runOnFunction(func);
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// 第一次调试打印输出
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std::stringstream ss_after_isel;
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RISCv64AsmPrinter printer_isel(mfunc.get());
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printer_isel.run(ss_after_isel, true);
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if (DEBUG) {
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std::cout << ss_after_isel.str();
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}
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if (DEBUG) {
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std::cerr << "====== Intermediate Representation after Instruction Selection ======\n"
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<< ss_after_isel.str();
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}
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// 阶段 2: 消除帧索引 (展开伪指令，计算局部变量偏移)
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// 这个Pass必须在寄存器分配之前运行
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EliminateFrameIndicesPass efi_pass;
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efi_pass.runOnMachineFunction(mfunc.get());
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if (DEBUG) {
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std::cerr << "====== stack info after eliminate frame indices ======\n";
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mfunc->dumpStackFrameInfo(std::cerr);
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std::stringstream ss_after_eli;
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printer_isel.run(ss_after_eli, true);
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std::cerr << "====== LLIR after eliminate frame indices ======\n"
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<< ss_after_eli.str();
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}
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// 阶段 2: 除法强度削弱优化 (Division Strength Reduction)
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DivStrengthReduction div_strength_reduction;
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div_strength_reduction.runOnMachineFunction(mfunc.get());
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// 阶段 2.1: 指令调度 (Instruction Scheduling)
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PreRA_Scheduler scheduler;
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scheduler.runOnMachineFunction(mfunc.get());
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// 阶段 3: 物理寄存器分配 (Register Allocation)
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RISCv64RegAlloc reg_alloc(mfunc.get());
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reg_alloc.run();
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if (DEBUG) {
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std::cerr << "====== stack info after reg alloc ======\n";
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mfunc->dumpStackFrameInfo(std::cerr);
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}
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// 阶段 3.1: 处理被调用者保存寄存器
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CalleeSavedHandler callee_handler;
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callee_handler.runOnMachineFunction(mfunc.get());
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if (DEBUG) {
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std::cerr << "====== stack info after callee handler ======\n";
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mfunc->dumpStackFrameInfo(std::cerr);
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}
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// 阶段 4: 窥孔优化 (Peephole Optimization)
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PeepholeOptimizer peephole;
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peephole.runOnMachineFunction(mfunc.get());
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// 阶段 5: 局部指令调度 (Local Scheduling)
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PostRA_Scheduler local_scheduler;
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local_scheduler.runOnMachineFunction(mfunc.get());
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// 阶段 3.2: 插入序言和尾声
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PrologueEpilogueInsertionPass pei_pass;
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pei_pass.runOnMachineFunction(mfunc.get());
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// 阶段 3.3: 大立即数合法化
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LegalizeImmediatesPass legalizer;
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legalizer.runOnMachineFunction(mfunc.get());
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// 阶段 6: 代码发射 (Code Emission)
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std::stringstream ss;
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RISCv64AsmPrinter printer(mfunc.get());
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printer.run(ss);
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return ss.str();
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}
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} // namespace sysy
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