TransPyC/lib/core/Handles/HandlesMatch.py

from __future__ import annotations
from typing import TYPE_CHECKING, Any
if TYPE_CHECKING:
    from lib.core.translator import Translator
from lib.core.Handles.HandlesBase import BaseHandle
import vast as ast
import llvmlite.ir as ir


class MatchHandle(BaseHandle):
    @staticmethod
    def _PatternCaptureNames(Pattern: ast.AST) -> list[str]:
        """模式中所有**捕获名**（递归 MatchOr/MatchClass/MatchSequence/MatchMapping）。

        用于判定"该 case 是否必须登记绑定"：有捕获却登记不上，case body 里的名字
        就会变成"未定义名称"，必须在**生成 body 之前**响亮失败，而不是留到取名时。
        """
        Names: list[str] = []
        if isinstance(Pattern, ast.MatchAs):
            if Pattern.name:
                Names.append(Pattern.name)
            if Pattern.pattern is not None:
                Names.extend(MatchHandle._PatternCaptureNames(Pattern.pattern))
        elif isinstance(Pattern, ast.MatchStar):
            if Pattern.name:
                Names.append(Pattern.name)
        elif isinstance(Pattern, (ast.MatchOr, ast.MatchSequence, ast.MatchClass, ast.MatchMapping)):
            for p in (getattr(Pattern, 'patterns', None) or []):
                Names.extend(MatchHandle._PatternCaptureNames(p))
            for p in (getattr(Pattern, 'kwd_patterns', None) or []):
                Names.extend(MatchHandle._PatternCaptureNames(p))
            _rest: str | None = getattr(Pattern, 'rest', None)
            if _rest:
                Names.append(_rest)
        return Names

    def _HandleMatchLlvm(self, Node: ast.Match) -> None:
        Gen: "Translator.LlvmGen" = self.Trans.LlvmGen
        # 重名 case 检测（fail-fast）：C 的 switch 不允许重复 case 标签——重复标签会让
        # 某个臂永远不可达，且通常意味着漏改的分支；`case _`（default）同样只允许一个。
        # 在产出任何 IR 之前检查，保证报错即终止。
        SeenLabels: dict[str, int] = {}
        DefaultCount: int = 0
        for ci, case in enumerate(Node.cases):
            Key: str | None = MatchHandle._CaseLabelKey(case.pattern)
            if Key is None:
                if isinstance(case.pattern, ast.MatchAs) and case.pattern.pattern is None:
                    DefaultCount += 1
                continue
            if Key in SeenLabels:
                from lib.core.LLVMCG.FuncGen import FailFastError
                raise FailFastError(
                    f"match 出现重名 case：标签 '{Key}' 已在第 {SeenLabels[Key]} 个 case 使用，"
                    f"第 {ci} 个 case 重复（C switch 不允许重复 case 标签）")
            SeenLabels[Key] = ci
        if DefaultCount > 1:
            from lib.core.LLVMCG.FuncGen import FailFastError
            raise FailFastError(
                f"match 出现 {DefaultCount} 个 `case _`（default 只允许一个）")
        SubjectVal: ir.Value | None = self.HandleExprLlvm(Node.subject)
        if not SubjectVal:
            return

        IsRenumMatch: bool = False
        RenumName: str | None = None
        SubjectPtr: ir.Value | None = None
        if isinstance(Node.subject, ast.Name):
            VarName: str = Node.subject.id
            TypeInfo: "SymbolTable.SymbolInfo | None" = self.Trans.SymbolTable.lookup(VarName)
            if TypeInfo and TypeInfo.IsRenum:
                    IsRenumMatch = True
                    RenumName = TypeInfo.Name
                    SubjectPtr = Gen._Load_var(VarName)

        if not IsRenumMatch:
            for case in Node.cases:
                if isinstance(case.pattern, ast.MatchClass):
                    cls_node: ast.expr = case.pattern.cls
                    VariantName: str | None = None
                    QualifiedName: str | None = None
                    if isinstance(cls_node, ast.Name):
                        VariantName = cls_node.id
                    elif isinstance(cls_node, ast.Attribute):
                        VariantName = cls_node.attr
                        # Extract enum name for qualified lookup to avoid collision
                        # with same-name factory functions (e.g. def Ptr vs LLVMType.Ptr)
                        if isinstance(cls_node.value, ast.Attribute):
                            QualifiedName = f"{cls_node.value.attr}.{VariantName}"
                        elif isinstance(cls_node.value, ast.Name):
                            QualifiedName = f"{cls_node.value.id}.{VariantName}"
                    if VariantName:
                        # Try qualified name first (e.g., "LLVMType.Ptr") to avoid
                        # collision with same-name functions (e.g., def Ptr(...))
                        SymInfo: "SymbolTable.SymbolInfo" = None
                        if QualifiedName:
                            SymInfo = self.Trans.SymbolTable.lookup(QualifiedName)
                        if not (SymInfo and SymInfo.IsEnumMember):
                            SymInfo = self.Trans.SymbolTable.lookup(VariantName)
                        if SymInfo and SymInfo.IsEnumMember and SymInfo.EnumName:
                            EnumName: str = SymInfo.EnumName
                            EnumInfo: "SymbolTable.SymbolInfo" = self.Trans.SymbolTable.lookup(EnumName)
                            if EnumInfo and EnumInfo.IsRenum:
                                IsRenumMatch = True
                                RenumName = EnumName
                                if SubjectPtr is None:
                                    SubjectPtr = self.HandleExprLlvm(Node.subject)
                                break

        if IsRenumMatch and SubjectPtr:
            self._HandleRenumMatchLlvm(Node, RenumName, SubjectPtr)
            return

        if not isinstance(SubjectVal.type, ir.IntType):
            try:
                SubjectVal = Gen.builder.ptrtoint(SubjectVal, ir.IntType(64), name="match_subj")
                SubjectVal = Gen.builder.trunc(SubjectVal, ir.IntType(32), name="match_subj_i32")
            except Exception:  # 回退：ptrtoint 失败时直接返回
                return
        SwitchIntType: ir.IntType = SubjectVal.type
        DefaultBB: ir.Block = Gen.func.append_basic_block(name="match.default")
        AfterBB: ir.Block = Gen.func.append_basic_block(name="match.end")
        CaseBBs: list[ir.Block] = []
        CaseValues: list[ir.Value] = []
        HasDefault: bool = False
        HasNoBreak: list[bool] = []
        for i, case in enumerate(Node.cases):
            pattern: ast.pattern = case.pattern
            if isinstance(pattern, ast.MatchValue):
                Val: ir.Value | None = self.HandleExprLlvm(pattern.value)
                if Val:
                    CaseVal: ir.Value
                    if isinstance(Val.type, ir.IntType):
                        if Val.type != SwitchIntType:
                            if Val.type.width > SwitchIntType.width:
                                CaseVal = ir.Constant(SwitchIntType, Val.constant & ((1 << SwitchIntType.width) - 1))
                            else:
                                CaseVal = ir.Constant(SwitchIntType, Val.constant)
                        else:
                            CaseVal = Val
                    else:
                        try:
                            CaseVal = Gen.builder.ptrtoint(Val, SwitchIntType, name=f"case_val_{i}")
                        except Exception:  # 回退：ptrtoint 失败时设默认值 0
                            CaseVal = ir.Constant(SwitchIntType, 0)
                    CaseValues.append(CaseVal)
                    CaseBBs.append(Gen.func.append_basic_block(name=f"match.case_{i}"))
            elif isinstance(pattern, ast.MatchOr):
                for j, SubPattern in enumerate(pattern.patterns):
                    if isinstance(SubPattern, ast.MatchValue):
                        Val: ir.Value | None = self.HandleExprLlvm(SubPattern.value)
                        if Val:
                            CaseVal: ir.Value
                            if isinstance(Val.type, ir.IntType):
                                if Val.type != SwitchIntType:
                                    if Val.type.width > SwitchIntType.width:
                                        CaseVal = ir.Constant(SwitchIntType, Val.constant & ((1 << SwitchIntType.width) - 1))
                                    else:
                                        CaseVal = ir.Constant(SwitchIntType, Val.constant)
                                else:
                                    CaseVal = Val
                            else:
                                try:
                                    CaseVal = Gen.builder.ptrtoint(Val, SwitchIntType, name=f"case_val_{i}_{j}")
                                except Exception:  # 回退：ptrtoint 失败时设默认值 0
                                    CaseVal = ir.Constant(SwitchIntType, 0)
                            CaseValues.append(CaseVal)
                            CaseBBs.append(Gen.func.append_basic_block(name=f"match.case_{i}_{j}"))
            elif isinstance(pattern, ast.MatchSingleton):
                if pattern.value is None:
                    CaseValues.append(ir.Constant(SwitchIntType, 0))
                    CaseBBs.append(Gen.func.append_basic_block(name=f"match.case_{i}"))
            elif isinstance(pattern, ast.MatchAs):
                if pattern.pattern is None:
                    HasDefault = True
                    CaseBBs.append(DefaultBB)
            elif isinstance(pattern, ast.MatchSequence):
                HasDefault = True
                CaseBBs.append(DefaultBB)
            elif isinstance(pattern, ast.MatchClass):
                # 兜底处理：REnum 检测失败但 case 是 MatchClass（REnum 变体模式）
                # 尝试从变体名查找 tag 值，按整数值处理
                cls_node_mc: ast.expr = pattern.cls
                VariantName_mc: str | None = None
                QualifiedName_mc: str | None = None
                if isinstance(cls_node_mc, ast.Name):
                    VariantName_mc = cls_node_mc.id
                elif isinstance(cls_node_mc, ast.Attribute):
                    VariantName_mc = cls_node_mc.attr
                    if isinstance(cls_node_mc.value, ast.Attribute):
                        QualifiedName_mc = f"{cls_node_mc.value.attr}.{VariantName_mc}"
                    elif isinstance(cls_node_mc.value, ast.Name):
                        QualifiedName_mc = f"{cls_node_mc.value.id}.{VariantName_mc}"
                TagValue_mc: int | None = None
                SymInfo_mc: "SymbolTable.SymbolInfo" = None
                if QualifiedName_mc:
                    SymInfo_mc = self.Trans.SymbolTable.lookup(QualifiedName_mc)
                if not (SymInfo_mc and SymInfo_mc.IsEnumMember):
                    SymInfo_mc = self.Trans.SymbolTable.lookup(VariantName_mc)
                if SymInfo_mc and SymInfo_mc.IsEnumMember:
                    TagValue_mc = SymInfo_mc.value
                if TagValue_mc is not None:
                    # 兜底分支**不登记捕获绑定**（它按整数 tag 处理，无变体载荷可 GEP）。
                    # 因此只要该 case 有捕获，就必须在此 fail-fast —— 否则 case body 里的
                    # 绑定名随后变成"未定义名称"（现场 VpiReader.vp:1521 pointee_cs），
                    # 真因（外层 REnum 判定未成立）被掩盖。报文直接列出判据供定位。
                    _caps_mc: list[str] = self._PatternCaptureNames(pattern)
                    if _caps_mc:
                        from lib.core.LLVMCG.FuncGen import FailFastError
                        _en_mc: str | None = getattr(SymInfo_mc, 'EnumName', None)
                        _sym_en: "SymbolTable.SymbolInfo" = (
                            self.Trans.SymbolTable.lookup(_en_mc) if _en_mc else None)
                        _sym_v: "SymbolTable.SymbolInfo" = (
                            self.Trans.SymbolTable.lookup(VariantName_mc) if VariantName_mc else None)
                        raise FailFastError(
                            f"REnum 变体模式 '{QualifiedName_mc or VariantName_mc}' 含捕获 {_caps_mc}，"
                            f"但外层 REnum 匹配判定未成立（IsRenumMatch=False）⇒ 兜底分支不登记捕获绑定，"
                            f"case body 里这些名字必然成为'未定义名称'。判据："
                            f"符号表['{QualifiedName_mc}'] => "
                            f"IsEnumMember={getattr(SymInfo_mc, 'IsEnumMember', None)} "
                            f"value={getattr(SymInfo_mc, 'value', None)} EnumName={_en_mc!r}；"
                            f"符号表['{_en_mc}'] => IsRenum={getattr(_sym_en, 'IsRenum', None)} "
                            f"IsStruct={getattr(_sym_en, 'IsStruct', None)} "
                            f"IsEnum={getattr(_sym_en, 'IsEnum', None)}；"
                            f"符号表['{VariantName_mc}'] => "
                            f"IsEnumMember={getattr(_sym_v, 'IsEnumMember', None)} "
                            f"EnumName={getattr(_sym_v, 'EnumName', None)!r}"
                        )
                    CaseValues.append(ir.Constant(SwitchIntType, TagValue_mc))
                    CaseBBs.append(Gen.func.append_basic_block(name=f"match.case_{VariantName_mc}"))
                else:
                    # 变体名未找到，跳过此 case（fast-fail 已在外层处理）
                    pass
            def _HasNoBreak(stmts: list[ast.stmt]) -> bool:
                for stmt in stmts:
                    if isinstance(stmt, ast.Expr) and isinstance(stmt.value, ast.Call):
                        if isinstance(stmt.value.func, ast.Attribute):
                            if (isinstance(stmt.value.func.value, ast.Name) and
                                stmt.value.func.value.id == 'c' and
                                stmt.value.func.attr == 'NoBreak'):
                                return True
                    if getattr(stmt, 'body', None) and isinstance(stmt.body, list):
                        if _HasNoBreak(stmt.body):
                            return True
                    if getattr(stmt, 'orelse', None):
                        if isinstance(stmt.orelse, list) and _HasNoBreak(stmt.orelse):
                            return True
                return False
            HasNoBreak.append(_HasNoBreak(case.body) if case.body else False)
        if not HasDefault:
            CaseBBs.append(DefaultBB)
        SwitchCases: list[tuple[ir.Value, ir.Block]] = [(val, bb) for val, bb in zip(CaseValues, CaseBBs) if bb != DefaultBB]
        switch_instr: ir.SwitchInstr = Gen.builder.switch(SubjectVal, DefaultBB)
        for val, bb in SwitchCases:
            switch_instr.add_case(val, bb)
        CaseIdx: int = 0
        for i, case in enumerate(Node.cases):
            pattern: ast.pattern = case.pattern
            if isinstance(pattern, ast.MatchOr):
                NumSubCases: int = len(pattern.patterns)
                for j in range(NumSubCases):
                    if CaseIdx < len(CaseBBs) and CaseBBs[CaseIdx] != DefaultBB:
                        Gen.builder.position_at_start(CaseBBs[CaseIdx])
                        self._HandleMatchCaseBody(Gen, case.body, AfterBB)
                        if not Gen.builder.block.is_terminated:
                            if not HasNoBreak[i]:
                                Gen.builder.branch(AfterBB)
                            else:
                                Gen.builder.branch(self._FallThroughTarget(CaseBBs, CaseIdx, AfterBB))
                        CaseIdx += 1
            elif isinstance(pattern, (ast.MatchValue, ast.MatchSingleton)):
                if CaseIdx < len(CaseBBs) and CaseBBs[CaseIdx] != DefaultBB:
                    Gen.builder.position_at_start(CaseBBs[CaseIdx])
                    self._HandleMatchCaseBody(Gen, case.body, AfterBB)
                    if not Gen.builder.block.is_terminated:
                        if not HasNoBreak[i]:
                            Gen.builder.branch(AfterBB)
                        else:
                            Gen.builder.branch(self._FallThroughTarget(CaseBBs, CaseIdx, AfterBB))
                    CaseIdx += 1
            elif isinstance(pattern, ast.MatchAs):
                if pattern.pattern is None:
                    Gen.builder.position_at_start(DefaultBB)
                    self._HandleMatchCaseBody(Gen, case.body, AfterBB)
                    if not Gen.builder.block.is_terminated:
                        if not HasNoBreak[i]:
                            Gen.builder.branch(AfterBB)
                        else:
                            Gen.builder.branch(self._FallThroughTarget(CaseBBs, CaseIdx, AfterBB))
                    CaseIdx += 1
            elif isinstance(pattern, ast.MatchSequence):
                Gen.builder.position_at_start(DefaultBB)
                self._HandleMatchCaseBody(Gen, case.body, AfterBB)
                if not Gen.builder.block.is_terminated:
                    if not HasNoBreak[i]:
                        Gen.builder.branch(AfterBB)
                    else:
                        Gen.builder.branch(self._FallThroughTarget(CaseBBs, CaseIdx, AfterBB))
                CaseIdx += 1
            elif isinstance(pattern, ast.MatchClass):
                # 兜底处理：MatchClass 在非 REnum 路径的 case body 生成
                # case 收集阶段已创建 CaseBB，此处生成 body
                if CaseIdx < len(CaseBBs) and CaseBBs[CaseIdx] != DefaultBB:
                    Gen.builder.position_at_start(CaseBBs[CaseIdx])
                    self._HandleMatchCaseBody(Gen, case.body, AfterBB)
                    if not Gen.builder.block.is_terminated:
                        if not HasNoBreak[i]:
                            Gen.builder.branch(AfterBB)
                        else:
                            Gen.builder.branch(self._FallThroughTarget(CaseBBs, CaseIdx, AfterBB))
                    CaseIdx += 1
        if not HasDefault:
            Gen.builder.position_at_start(DefaultBB)
            Gen.builder.branch(AfterBB)
        elif not any(isinstance(c.pattern, ast.MatchAs) and c.pattern.pattern is None for c in Node.cases) and not any(isinstance(c.pattern, ast.MatchSequence) for c in Node.cases):
            Gen.builder.position_at_start(DefaultBB)
            Gen.builder.branch(AfterBB)
        Gen.builder.position_at_start(AfterBB)

    def _HandleMatchCaseBody(self, Gen: "Translator.LlvmGen",
                             Body: list[ast.stmt], AfterBB: ir.Block) -> None:
        """翻译 match case 体：case 体内的 break 目标是 match 的 AfterBB

        C switch 语义——case 内 break 跳出 **match**（而非外层循环）。故翻译前把
        AfterBB 压入 loop_break_targets，翻译完弹出（外层循环目标不受影响）。
        """
        Targets: list = Gen.loop_break_targets
        Targets.append(AfterBB)
        try:
            self.HandleBodyLlvm(Body)
        finally:
            Targets.pop()

    @staticmethod
    def _FallThroughTarget(CaseBBs: list[ir.Block], CaseIdx: int, AfterBB: ir.Block) -> ir.Block:
        """fallthrough 的落点：下一个 case 的 body（无后继槽位时落到 AfterBB）

        `fallthrough`（vast 软关键字，脱糖为 c.NoBreak()）表示"本 case 不自动
        break"，直接落到下一个 case 的 body（对齐 C 的 [[fallthrough]]）。
        """
        NextIdx: int = CaseIdx + 1
        if 0 <= NextIdx < len(CaseBBs):
            return CaseBBs[NextIdx]
        return AfterBB

    def _HandleRenumMatchLlvm(self, Node: ast.Match, RenumName: str, SubjectPtr: ir.Value) -> None:
        Gen: "Translator.LlvmGen" = self.Trans.LlvmGen
        if isinstance(SubjectPtr.type, ir.PointerType) and isinstance(SubjectPtr.type.pointee, ir.PointerType):
            SubjectPtr = Gen._load(SubjectPtr, name="Load_match_subj")
        # Bug fix: HandleExprLlvm 可能对 REnum 字段执行了 load，返回值而非指针。
        # 情况1: SubjectPtr 不是指针类型（如 IntType）→ alloca REnum 结构体 + store
        # 情况2: SubjectPtr 是指针但 pointee 不是结构体（如 i32* 指向 __tag）→ bitcast
        NeedAlloca: bool = not isinstance(SubjectPtr.type, ir.PointerType)
        NeedBitcast: bool = (isinstance(SubjectPtr.type, ir.PointerType) and
                             not isinstance(SubjectPtr.type.pointee, (ir.IdentifiedStructType, ir.LiteralStructType)))
        if NeedAlloca or NeedBitcast:
            RenumStructType: Any = Gen.structs.get(RenumName)
            if RenumStructType is None:
                # 跨模块编译时 REnum 结构体可能尚未在 Gen.structs 中注册
                # （如 import llvmlite 后 LLVMType 仅在符号表，Gen.structs 无条目）。
                # 使用 _get_or_create_struct 按需创建（可能为 opaque）。
                RenumStructType = Gen._get_or_create_struct(RenumName)
            if NeedAlloca:
                AllocaPtr: ir.Value = Gen._allocaEntry(RenumStructType, name="match_subj_alloca")
                CastedPtr: ir.Value = Gen.builder.bitcast(AllocaPtr, ir.PointerType(SubjectPtr.type), name="match_subj_cast")
                Gen._store(SubjectPtr, CastedPtr)
                SubjectPtr = AllocaPtr
            else:
                SubjectPtr = Gen.builder.bitcast(SubjectPtr, ir.PointerType(RenumStructType), name="match_subj_recast")
        # REnum 布局为 { i32 __tag, <payload> }，tag 在偏移 0。
        # 使用 bitcast 到 i32* 替代 gep [0,0]，兼容 opaque 结构体
        # （跨模块编译时 REnum 结构体可能未 set_body，gep 会失败）。
        tag_ptr: ir.Value = Gen.builder.bitcast(SubjectPtr, ir.PointerType(ir.IntType(32)), name="match_tag_ptr")
        TagVal: ir.Value = Gen._load(tag_ptr, name="match_tag_val")
        DefaultBB: ir.Block = Gen.func.append_basic_block(name="match.default")
        AfterBB: ir.Block = Gen.func.append_basic_block(name="match.end")
        CaseBBs: list[ir.Block] = []
        CaseValues: list[ir.Value] = []
        CaseBindings: list[list[tuple[str, str, ir.Type, int]]] = []
        HasDefault: bool = False
        HasNoBreak: list[bool] = []
        for i, case in enumerate(Node.cases):
            pattern: ast.pattern = case.pattern
            bindings: list[tuple[str, str, ir.Type, int]] = []
            if isinstance(pattern, ast.MatchClass):
                cls_node: ast.expr = pattern.cls
                VariantName: str | None = None
                QualifiedName: str | None = None
                if isinstance(cls_node, ast.Name):
                    VariantName = cls_node.id
                elif isinstance(cls_node, ast.Attribute):
                    VariantName = cls_node.attr
                    if isinstance(cls_node.value, ast.Attribute):
                        QualifiedName = f"{cls_node.value.attr}.{VariantName}"
                    elif isinstance(cls_node.value, ast.Name):
                        QualifiedName = f"{cls_node.value.id}.{VariantName}"
                if VariantName:
                    TagValue: int | None = None
                    SymInfo: "SymbolTable.SymbolInfo" = None
                    if QualifiedName:
                        SymInfo = self.Trans.SymbolTable.lookup(QualifiedName)
                    if not (SymInfo and SymInfo.IsEnumMember):
                        SymInfo = self.Trans.SymbolTable.lookup(VariantName)
                    if SymInfo and SymInfo.IsEnumMember:
                        TagValue = SymInfo.value
                    if TagValue is not None:
                        CaseValues.append(ir.Constant(ir.IntType(32), TagValue))
                        CaseBB: ir.Block = Gen.func.append_basic_block(name=f"match.case_{VariantName}")
                        CaseBBs.append(CaseBB)
                        # 变体嵌套结构体按需补发：导入模块侧 stub 只声明主 REnum，
                        # 不含 `<REnum>_<Variant>` 声明（见 _EnsureRenumVariantStruct）。
                        NestedStructName: str = self._EnsureRenumVariantStruct(Gen, RenumName, VariantName)
                        members: list[tuple[str, ir.Type]] = Gen.class_members.get(NestedStructName, [])
                        payLoad_members: list[tuple[str, ir.Type]] = [(n, t) for n, t in members if n != '__tag']
                        # 模式捕获必须能全部绑定：绑不上就在此 fail-fast，绝不让 case body
                        # 里的绑定名留到后面变成"未定义名称"（现场 VpiReader.vp:1521 pointee_cs）。
                        _captures: list[str] = [p.name for p in pattern.patterns
                                                if isinstance(p, ast.MatchAs) and p.name]
                        if _captures and len(payLoad_members) < len(_captures):
                            from lib.core.LLVMCG.FuncGen import FailFastError
                            raise FailFastError(
                                f"REnum 变体模式 '{RenumName}.{VariantName}' 的载荷成员不足，"
                                f"无法绑定模式捕获 {_captures}："
                                f"class_members['{NestedStructName}']={len(members)} 项"
                                f"（去 __tag 后载荷 {len(payLoad_members)} 项）；"
                                f"structs 命中={'有' if NestedStructName in Gen.structs else '无'}；"
                                f"同前缀 structs 键="
                                f"{[k for k in Gen.structs if k.startswith(RenumName + '_')][:8]}"
                            )
                        for j, sub_pat in enumerate(pattern.patterns):
                            if isinstance(sub_pat, ast.MatchAs) and sub_pat.name and j < len(payLoad_members):
                                bindings.append((sub_pat.name, payLoad_members[j][0], payLoad_members[j][1], j))
                        CaseBindings.append(bindings)
                    else:
                        CaseValues.append(ir.Constant(ir.IntType(32), 0))
                        CaseBBs.append(Gen.func.append_basic_block(name=f"match.case_{i}"))
                        CaseBindings.append([])
            elif isinstance(pattern, ast.MatchValue):
                Val: ir.Value | None = self.HandleExprLlvm(pattern.value)
                if Val:
                    CaseVal: ir.Value
                    if isinstance(Val.type, ir.IntType):
                        CaseVal = Val
                    else:
                        try:
                            CaseVal = Gen.builder.ptrtoint(Val, ir.IntType(32), name=f"case_val_{i}")
                        except Exception:  # 回退：ptrtoint 失败时设默认值 0
                            CaseVal = ir.Constant(ir.IntType(32), 0)
                    CaseValues.append(CaseVal)
                    CaseBBs.append(Gen.func.append_basic_block(name=f"match.case_{i}"))
                    CaseBindings.append([])
            elif isinstance(pattern, ast.MatchAs):
                if pattern.pattern is None:
                    HasDefault = True
                    CaseBBs.append(DefaultBB)
                    CaseBindings.append([])
            elif isinstance(pattern, ast.MatchSequence):
                HasDefault = True
                CaseBBs.append(DefaultBB)
                CaseBindings.append([])
            def _HasNoBreak(stmts: list[ast.stmt]) -> bool:
                for stmt in stmts:
                    if isinstance(stmt, ast.Expr) and isinstance(stmt.value, ast.Call):
                        if isinstance(stmt.value.func, ast.Attribute):
                            if (isinstance(stmt.value.func.value, ast.Name) and
                                stmt.value.func.value.id == 'c' and
                                stmt.value.func.attr == 'NoBreak'):
                                return True
                    if getattr(stmt, 'body', None) and isinstance(stmt.body, list):
                        if _HasNoBreak(stmt.body):
                            return True
                    if getattr(stmt, 'orelse', None):
                        if isinstance(stmt.orelse, list) and _HasNoBreak(stmt.orelse):
                            return True
                return False
            HasNoBreak.append(_HasNoBreak(case.body) if case.body else False)
        if not HasDefault:
            CaseBBs.append(DefaultBB)
        SwitchCases: list[tuple[ir.Value, ir.Block]] = [(val, bb) for val, bb in zip(CaseValues, CaseBBs) if bb != DefaultBB]
        switch_instr: ir.SwitchInstr = Gen.builder.switch(TagVal, DefaultBB)
        for val, bb in SwitchCases:
            switch_instr.add_case(val, bb)
        CaseIdx: int = 0
        for i, case in enumerate(Node.cases):
            pattern: ast.pattern = case.pattern
            if isinstance(pattern, ast.MatchClass):
                if CaseIdx < len(CaseBBs) and CaseBBs[CaseIdx] != DefaultBB:
                    Gen.builder.position_at_start(CaseBBs[CaseIdx])
                    bindings: list[tuple[str, str, ir.Type, int]] = CaseBindings[CaseIdx] if CaseIdx < len(CaseBindings) else []
                    cls_node: ast.expr = pattern.cls
                    VariantName: str | None = None
                    if isinstance(cls_node, ast.Name):
                        VariantName = cls_node.id
                    elif isinstance(cls_node, ast.Attribute):
                        VariantName = cls_node.attr
                    if VariantName:
                        NestedStructName: str = f"{RenumName}_{VariantName}"
                        if NestedStructName in Gen.structs:
                            NestedStructType: ir.Type = Gen.structs[NestedStructName]
                            # 变体 struct 可能仍是 opaque（body 未 set_body / 同名两份实例）
                            # ⇒ 先取已具化实例，否则 GEP 在编译期算不出元素类型（判据见
                            # ExprAttrHandle._ConcretePointeeFor）。
                            _TwV: Any = self.Trans.ExprAttrHandle._ConcretePointeeFor(
                                Gen, NestedStructName, NestedStructType)
                            if isinstance(_TwV, ir.IdentifiedStructType):
                                NestedStructType = _TwV
                            NestedStructPtrType: ir.PointerType = ir.PointerType(NestedStructType)
                            variant_ptr: ir.Value = Gen.builder.bitcast(SubjectPtr, NestedStructPtrType, name=f"match_cast_{VariantName}")
                            for bind_name, member_name, member_type, member_idx in bindings:
                                elem_ptr: ir.Value = Gen.builder.gep(variant_ptr, [ir.Constant(ir.IntType(32), 0), ir.Constant(ir.IntType(32), member_idx + 1)], name=f"match_{bind_name}")
                                # REnum 嵌套结构体共享 max_variant_struct 布局，成员类型可能与
                                # 结构体字段类型不一致。bitcast 到成员类型以确保后续 load 得到正确类型。
                                if isinstance(elem_ptr.type, ir.PointerType) and elem_ptr.type.pointee != member_type:
                                    elem_ptr = Gen.builder.bitcast(elem_ptr, ir.PointerType(member_type), name=f"match_{bind_name}_cast")
                                Gen.variables[bind_name] = elem_ptr
                    self._HandleMatchCaseBody(Gen, case.body, AfterBB)
                    for bind_name, _, _, _ in bindings:
                        if bind_name in Gen.variables:
                            del Gen.variables[bind_name]
                    if not Gen.builder.block.is_terminated:
                        if not HasNoBreak[i]:
                            Gen.builder.branch(AfterBB)
                        else:
                            Gen.builder.branch(self._FallThroughTarget(CaseBBs, CaseIdx, AfterBB))
                    CaseIdx += 1
            elif isinstance(pattern, ast.MatchValue):
                if CaseIdx < len(CaseBBs) and CaseBBs[CaseIdx] != DefaultBB:
                    Gen.builder.position_at_start(CaseBBs[CaseIdx])
                    self._HandleMatchCaseBody(Gen, case.body, AfterBB)
                    if not Gen.builder.block.is_terminated:
                        if not HasNoBreak[i]:
                            Gen.builder.branch(AfterBB)
                        else:
                            Gen.builder.branch(self._FallThroughTarget(CaseBBs, CaseIdx, AfterBB))
                    CaseIdx += 1
            elif isinstance(pattern, ast.MatchAs):
                if pattern.pattern is None:
                    Gen.builder.position_at_start(DefaultBB)
                    self._HandleMatchCaseBody(Gen, case.body, AfterBB)
                    if not Gen.builder.block.is_terminated:
                        if not HasNoBreak[i]:
                            Gen.builder.branch(AfterBB)
                        else:
                            Gen.builder.branch(self._FallThroughTarget(CaseBBs, CaseIdx, AfterBB))
                    CaseIdx += 1
            elif isinstance(pattern, ast.MatchSequence):
                Gen.builder.position_at_start(DefaultBB)
                self._HandleMatchCaseBody(Gen, case.body, AfterBB)
                if not Gen.builder.block.is_terminated:
                    if not HasNoBreak[i]:
                        Gen.builder.branch(AfterBB)
                    else:
                        Gen.builder.branch(self._FallThroughTarget(CaseBBs, CaseIdx, AfterBB))
                CaseIdx += 1
        if not HasDefault:
            Gen.builder.position_at_start(DefaultBB)
            Gen.builder.branch(AfterBB)
        elif not any(isinstance(c.pattern, ast.MatchAs) and c.pattern.pattern is None for c in Node.cases) and not any(isinstance(c.pattern, ast.MatchSequence) for c in Node.cases):
            Gen.builder.position_at_start(DefaultBB)
            Gen.builder.branch(AfterBB)
        Gen.builder.position_at_start(AfterBB)