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[backend]将浮点逻辑改为与开发板一致

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This commit is contained in:
Lixuanwang
2025-08-05 01:08:42 +08:00
parent dcc075b39c
commit df50eedaeb
1 changed files with 77 additions and 6 deletions
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83
src/backend/RISCv64/RISCv64ISel.cpp
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@ -745,12 +745,83 @@ void RISCv64ISel::selectNode(DAGNode* node) {
CurMBB->addInstruction(std::move(instr));
break;
}
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));
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));
break;
}
case Instruction::kFNeg: { // 浮点取负