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#include "mir/MIR.h"
#include <stdexcept>
#include <unordered_map>
#include "ir/IR.h"
#include "utils/Log.h"
namespace mir {
namespace {
using ValueSlotMap = std::unordered_map<const ir::Value*, int>;
void EmitValueToReg(const ir::Value* value, PhysReg target,
const ValueSlotMap& slots, MachineBasicBlock& block) {
if (auto* constant = dynamic_cast<const ir::ConstantInt*>(value)) {
block.Append(Opcode::MovImm,
{Operand::Reg(target), Operand::Imm(constant->value())});
return;
}
auto it = slots.find(value);
if (it == slots.end()) {
throw std::runtime_error(
FormatError("mir", "找不到值对应的栈槽: " + value->name()));
}
block.Append(Opcode::LoadStack,
{Operand::Reg(target), Operand::FrameIndex(it->second)});
}
void LowerInstruction(const ir::Instruction& inst, MachineFunction& function,
ValueSlotMap& slots) {
auto& block = function.entry();
switch (inst.opcode()) {
case ir::Opcode::Alloca: {
slots.emplace(&inst, function.CreateFrameIndex());
return;
}
case ir::Opcode::Store: {
auto& store = static_cast<const ir::StoreInst&>(inst);
auto dst = slots.find(store.ptr());
if (dst == slots.end()) {
throw std::runtime_error(
FormatError("mir", "暂不支持对非栈变量地址进行写入"));
}
EmitValueToReg(store.value(), PhysReg::W8, slots, block);
block.Append(Opcode::StoreStack,
{Operand::Reg(PhysReg::W8), Operand::FrameIndex(dst->second)});
return;
}
case ir::Opcode::Load: {
auto& load = static_cast<const ir::LoadInst&>(inst);
auto src = slots.find(load.ptr());
if (src == slots.end()) {
throw std::runtime_error(
FormatError("mir", "暂不支持对非栈变量地址进行读取"));
}
int dst_slot = function.CreateFrameIndex();
block.Append(Opcode::LoadStack,
{Operand::Reg(PhysReg::W8), Operand::FrameIndex(src->second)});
block.Append(Opcode::StoreStack,
{Operand::Reg(PhysReg::W8), Operand::FrameIndex(dst_slot)});
slots.emplace(&inst, dst_slot);
return;
}
case ir::Opcode::Add: {
auto& bin = static_cast<const ir::BinaryInst&>(inst);
int dst_slot = function.CreateFrameIndex();
EmitValueToReg(bin.lhs(), PhysReg::W8, slots, block);
EmitValueToReg(bin.rhs(), PhysReg::W9, slots, block);
block.Append(Opcode::AddRR, {Operand::Reg(PhysReg::W8),
Operand::Reg(PhysReg::W8),
Operand::Reg(PhysReg::W9)});
block.Append(Opcode::StoreStack,
{Operand::Reg(PhysReg::W8), Operand::FrameIndex(dst_slot)});
slots.emplace(&inst, dst_slot);
return;
}
case ir::Opcode::Ret: {
auto& ret = static_cast<const ir::ReturnInst&>(inst);
EmitValueToReg(ret.value(), PhysReg::W0, slots, block);
block.Append(Opcode::Ret);
return;
}
case ir::Opcode::Sub:
case ir::Opcode::Mul:
throw std::runtime_error(FormatError("mir", "暂不支持该二元运算"));
}
throw std::runtime_error(FormatError("mir", "暂不支持该 IR 指令"));
}
} // namespace
std::unique_ptr<MachineFunction> LowerToMIR(const ir::Module& module) {
DefaultContext();
if (module.functions().size() != 1) {
throw std::runtime_error(FormatError("mir", "暂不支持多个函数"));
}
const auto& func = *module.functions().front();
if (func.name() != "main") {
throw std::runtime_error(FormatError("mir", "暂不支持非 main 函数"));
}
auto machine_func = std::make_unique<MachineFunction>(func.name());
ValueSlotMap slots;
const auto* entry = func.entry();
if (!entry) {
throw std::runtime_error(FormatError("mir", "IR 函数缺少入口基本块"));
}
for (const auto& inst : entry->instructions()) {
LowerInstruction(*inst, *machine_func, slots);
}
return machine_func;
}
} // namespace mir