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[backend]浮点逻辑与gcc保持一致

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This commit is contained in:
Lixuanwang
2025-08-04 21:54:24 +08:00
parent 881c2a9723
commit f7f1cf2b41
4 changed files with 18 additions and 87 deletions
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3
src/backend/RISCv64/RISCv64AsmPrinter.cpp
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@ -82,7 +82,7 @@ void RISCv64AsmPrinter::printInstruction(MachineInstr* instr, bool debug) {
case RVOpcodes::SB: *OS << "sb "; break; case RVOpcodes::LD: *OS << "ld "; break;
case RVOpcodes::SD: *OS << "sd "; break; case RVOpcodes::FLW: *OS << "flw "; break;
case RVOpcodes::FSW: *OS << "fsw "; break; case RVOpcodes::FLD: *OS << "fld "; break;
case RVOpcodes::FSD: *OS << "fsd "; break;
case RVOpcodes::FSD: *OS << "fsd "; break;
case RVOpcodes::J: *OS << "j "; break; case RVOpcodes::JAL: *OS << "jal "; break;
case RVOpcodes::JALR: *OS << "jalr "; break; case RVOpcodes::RET: *OS << "ret"; break;
case RVOpcodes::BEQ: *OS << "beq "; break; case RVOpcodes::BNE: *OS << "bne "; break;
@ -102,6 +102,7 @@ void RISCv64AsmPrinter::printInstruction(MachineInstr* instr, bool debug) {
case RVOpcodes::FLE_S: *OS << "fle.s "; break;
case RVOpcodes::FCVT_S_W: *OS << "fcvt.s.w "; break;
case RVOpcodes::FCVT_W_S: *OS << "fcvt.w.s "; break;
case RVOpcodes::FCVT_W_S_RTZ: *OS << "fcvt.w.s "; break;
case RVOpcodes::FMV_S: *OS << "fmv.s "; break;
case RVOpcodes::FMV_W_X: *OS << "fmv.w.x "; break;
case RVOpcodes::FMV_X_W: *OS << "fmv.x.w "; break;

100
src/backend/RISCv64/RISCv64ISel.cpp
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@ -745,83 +745,12 @@ void RISCv64ISel::selectNode(DAGNode* node) {
CurMBB->addInstruction(std::move(instr));
break;
}
case Instruction::kFtoI: { // 浮点 to 整数 (带向下取整)
// 目标：实现 floor(x) 的效果, C/C++中浮点转整数是截断(truncate)
// 对于正数，floor(x) == truncate(x)
// RISC-V的 fcvt.w.s 默认是“四舍五入到偶数”
// 我们需要手动实现截断逻辑
// 逻辑:
// temp_i = fcvt.w.s(x) // 四舍五入
// temp_f = fcvt.s.w(temp_i) // 转回浮点
// if (x < temp_f) { // 如果原数更小，说明被“五入”了
// result = temp_i - 1
// } else {
// result = temp_i
// }
auto temp_i_vreg = getNewVReg(Type::getIntType());
auto temp_f_vreg = getNewVReg(Type::getFloatType());
auto cmp_vreg = getNewVReg(Type::getIntType());
// 1. fcvt.w.s temp_i_vreg, src_vreg
auto fcvt_w = std::make_unique<MachineInstr>(RVOpcodes::FCVT_W_S);
fcvt_w->addOperand(std::make_unique<RegOperand>(temp_i_vreg));
fcvt_w->addOperand(std::make_unique<RegOperand>(src_vreg));
CurMBB->addInstruction(std::move(fcvt_w));
// 2. fcvt.s.w temp_f_vreg, temp_i_vreg
auto fcvt_s = std::make_unique<MachineInstr>(RVOpcodes::FCVT_S_W);
fcvt_s->addOperand(std::make_unique<RegOperand>(temp_f_vreg));
fcvt_s->addOperand(std::make_unique<RegOperand>(temp_i_vreg));
CurMBB->addInstruction(std::move(fcvt_s));
// 3. flt.s cmp_vreg, src_vreg, temp_f_vreg
auto flt = std::make_unique<MachineInstr>(RVOpcodes::FLT_S);
flt->addOperand(std::make_unique<RegOperand>(cmp_vreg));
flt->addOperand(std::make_unique<RegOperand>(src_vreg));
flt->addOperand(std::make_unique<RegOperand>(temp_f_vreg));
CurMBB->addInstruction(std::move(flt));
// 创建标签
int unique_id = this->local_label_counter++;
std::string rounded_up_label = MFunc->getName() + "_ftoi_rounded_up_" + std::to_string(unique_id);
std::string done_label = MFunc->getName() + "_ftoi_done_" + std::to_string(unique_id);
// 4. bne cmp_vreg, x0, rounded_up_label
auto bne = std::make_unique<MachineInstr>(RVOpcodes::BNE);
bne->addOperand(std::make_unique<RegOperand>(cmp_vreg));
bne->addOperand(std::make_unique<RegOperand>(PhysicalReg::ZERO));
bne->addOperand(std::make_unique<LabelOperand>(rounded_up_label));
CurMBB->addInstruction(std::move(bne));
// 5. else 分支: mv dest_vreg, temp_i_vreg
auto mv = std::make_unique<MachineInstr>(RVOpcodes::MV);
mv->addOperand(std::make_unique<RegOperand>(dest_vreg));
mv->addOperand(std::make_unique<RegOperand>(temp_i_vreg));
CurMBB->addInstruction(std::move(mv));
// 6. j done_label
auto j = std::make_unique<MachineInstr>(RVOpcodes::J);
j->addOperand(std::make_unique<LabelOperand>(done_label));
CurMBB->addInstruction(std::move(j));
// 7. rounded_up_label:
auto label_up = std::make_unique<MachineInstr>(RVOpcodes::LABEL);
label_up->addOperand(std::make_unique<LabelOperand>(rounded_up_label));
CurMBB->addInstruction(std::move(label_up));
// 8. addiw dest_vreg, temp_i_vreg, -1
auto addi = std::make_unique<MachineInstr>(RVOpcodes::ADDIW);
addi->addOperand(std::make_unique<RegOperand>(dest_vreg));
addi->addOperand(std::make_unique<RegOperand>(temp_i_vreg));
addi->addOperand(std::make_unique<ImmOperand>(-1));
CurMBB->addInstruction(std::move(addi));
// 9. done_label:
auto label_done = std::make_unique<MachineInstr>(RVOpcodes::LABEL);
label_done->addOperand(std::make_unique<LabelOperand>(done_label));
CurMBB->addInstruction(std::move(label_done));
case Instruction::kFtoI: { // 浮点 to 整数 (使用硬件指令进行向零截断)
// 直接生成一条带有 rtz 舍入模式的转换指令
auto instr = std::make_unique<MachineInstr>(RVOpcodes::FCVT_W_S_RTZ);
instr->addOperand(std::make_unique<RegOperand>(dest_vreg)); // 目标是整数vreg
instr->addOperand(std::make_unique<RegOperand>(src_vreg)); // 源是浮点vreg
CurMBB->addInstruction(std::move(instr));
break;
}
case Instruction::kFNeg: { // 浮点取负
@ -1202,10 +1131,11 @@ void RISCv64ISel::selectNode(DAGNode* node) {
auto r_value_byte = getVReg(memset->getValue());
// 为memset内部逻辑创建新的临时虚拟寄存器
auto r_counter = getNewVReg();
auto r_end_addr = getNewVReg();
auto r_current_addr = getNewVReg();
auto r_temp_val = getNewVReg();
Type* ptr_type = Type::getPointerType(Type::getIntType());
auto r_counter = getNewVReg(ptr_type);
auto r_end_addr = getNewVReg(ptr_type);
auto r_current_addr = getNewVReg(ptr_type);
auto r_temp_val = getNewVReg(Type::getIntType());
// 定义一系列lambda表达式来简化指令创建
auto add_instr = [&](RVOpcodes op, unsigned rd, unsigned rs1, unsigned rs2) {
@ -1296,7 +1226,7 @@ void RISCv64ISel::selectNode(DAGNode* node) {
// --- Step 1: 获取基地址 (此部分逻辑正确，保持不变) ---
auto base_ptr_node = node->operands[0];
auto current_addr_vreg = getNewVReg();
auto current_addr_vreg = getNewVReg(gep->getType());
if (auto alloca_base = dynamic_cast<AllocaInst*>(base_ptr_node->value)) {
auto frame_addr_instr = std::make_unique<MachineInstr>(RVOpcodes::FRAME_ADDR);
@ -1338,13 +1268,13 @@ void RISCv64ISel::selectNode(DAGNode* node) {
// 如果步长为0（例如对一个void类型或空结构体索引），则不产生任何偏移
if (stride != 0) {
// --- 为当前索引和步长生成偏移计算指令 ---
auto offset_vreg = getNewVReg();
auto offset_vreg = getNewVReg(Type::getIntType());
// 处理索引 - 区分常量与动态值
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();
index_vreg = getNewVReg(Type::getIntType());
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()));
@ -1362,7 +1292,7 @@ void RISCv64ISel::selectNode(DAGNode* node) {
CurMBB->addInstruction(std::move(mv));
} else {
// 步长不为1，需要生成乘法指令
auto size_vreg = getNewVReg();
auto size_vreg = getNewVReg(Type::getIntType());
auto li_size = std::make_unique<MachineInstr>(RVOpcodes::LI);
li_size->addOperand(std::make_unique<RegOperand>(size_vreg));
li_size->addOperand(std::make_unique<ImmOperand>(stride));

1
src/include/backend/RISCv64/RISCv64ISel.h
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@ -22,7 +22,6 @@ public:
// 公开接口，以便后续模块（如RegAlloc）可以查询或创建vreg
unsigned getVReg(Value* val);
unsigned getNewVReg() { return vreg_counter++; }
unsigned getNewVReg(Type* type);
unsigned getVRegCounter() const;
// 获取 vreg_map 的公共接口

1
src/include/backend/RISCv64/RISCv64LLIR.h
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@ -88,6 +88,7 @@ enum class RVOpcodes {
// 浮点转换
FCVT_S_W, // fcvt.s.w rd, rs1 (有符号整数 -> 单精度浮点)
FCVT_W_S, // fcvt.w.s rd, rs1 (单精度浮点 -> 有符号整数)
FCVT_W_S_RTZ, // fcvt.w.s rd, rs1, rtz (使用向零截断模式)
// 浮点传送/移动
FMV_S, // fmv.s rd, rs1 (浮点寄存器之间)