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Merge branch 'backend-bss' into backend

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This commit is contained in:
Lixuanwang
2025-07-28 17:31:47 +08:00
parent 2dd6a17fca 429e477776
commit fcc3806342
1 changed files with 51 additions and 5 deletions
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56
src/RISCv64Backend.cpp
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@ -16,13 +16,59 @@ std::string RISCv64CodeGen::code_gen() {
std::string RISCv64CodeGen::module_gen() {
std::stringstream ss;
// 1. 处理全局变量 (.data段)
if (!module->getGlobals().empty()) {
ss << ".data\n";
for (const auto& global : module->getGlobals()) {
// --- [新逻辑] 步骤1：将全局变量分为.data和.bss两组 ---
std::vector<GlobalValue*> data_globals;
std::vector<GlobalValue*> bss_globals;
for (const auto& global_ptr : module->getGlobals()) {
GlobalValue* global = global_ptr.get();
const auto& init_values = global->getInitValues();
// 判断是否为大型零初始化数组，以便放入.bss段
bool is_large_zero_array = false;
// 规则：初始化列表只有一项，且该项是值为0的整数，且数量大于一个阈值（例如16）
if (init_values.getValues().size() == 1) {
if (auto const_val = dynamic_cast<ConstantValue*>(init_values.getValues()[0])) {
if (const_val->isInt() && const_val->getInt() == 0 && init_values.getNumbers()[0] > 16) {
is_large_zero_array = true;
}
}
}
if (is_large_zero_array) {
bss_globals.push_back(global);
} else {
data_globals.push_back(global);
}
}
// --- [新逻辑] 步骤2：生成 .bss 段的代码 ---
if (!bss_globals.empty()) {
ss << ".bss\n"; // 切换到 .bss 段
for (GlobalValue* global : bss_globals) {
// 获取数组总大小（元素个数 * 元素大小）
// 在SysY中，我们假设元素都是4字节（int或float）
unsigned count = global->getInitValues().getNumbers()[0];
unsigned total_size = count * 4;
ss << " .align 3\n"; // 8字节对齐 (2^3)
ss << ".globl " << global->getName() << "\n";
ss << ".type " << global->getName() << ", @object\n";
ss << ".size " << global->getName() << ", " << total_size << "\n";
ss << global->getName() << ":\n";
// 使用 .space 指令来预留指定大小的零填充空间
ss << " .space " << total_size << "\n";
}
}
// --- [旧逻辑保留] 步骤3：生成 .data 段的代码 ---
if (!data_globals.empty()) {
ss << ".data\n"; // 切换到 .data 段
for (GlobalValue* global : data_globals) {
ss << ".globl " << global->getName() << "\n";
ss << global->getName() << ":\n";
const auto& init_values = global->getInitValues();
// 使用您原有的逻辑来处理显式初始化的值
for (size_t i = 0; i < init_values.getValues().size(); ++i) {
auto val = init_values.getValues()[i];
auto count = init_values.getNumbers()[i];
@ -41,7 +87,7 @@ std::string RISCv64CodeGen::module_gen() {
}
}
// 2. 处理函数 (.text段)
// --- 处理函数 (.text段) 的逻辑保持不变 ---
if (!module->getFunctions().empty()) {
ss << ".text\n";
for (const auto& func_pair : module->getFunctions()) {