spl/stage1/spl_ast2ir.c

/* spl_ast2ir.c AST IR lowering
 *
 * 设计要点 *  - 名称解析自包含：局部变类型用自身环境栈；顶层类函数sema root scope 与聚合成员表 *  -
 * 变量落在内存槽（@mem.alloca），写走 @mem.load/store；表达式临时值为 SSA *  - 控制流用"块表 +
 * fixup 补丁"：分跳转目标在函数末尾回填为块首指令node ref *  -
 * 聚合字段访问：读@agg.extract，写字节地址直写"（@mem.offset + @mem.store<72>?*  - 枚举=
 * agg.construct(enum)([tag, payload?])；match tag 分发 *  - defer 按作用域逆序执行（正常退/ ret /
 * break / continue 全覆盖） */

#include "spl_ast2ir.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* ================================================================
 * 基础访问
 * ================================================================ */

static spl_ast_node_t *node_at(const spl_sema_t *sema, spl_ast_node_ref_t ref) {
    if (!ref || ref >= sema->ast->buckets.size)
        return NULL;
    return &sema->ast->buckets.data[ref];
}

static spl_type_node_t *tn(const spl_sema_t *sema, spl_type_id_t tid) {
    return spl_type_node((spl_type_t *)&sema->type, tid);
}

static spl_def_node_t *def_at(const spl_sema_t *sema, spl_def_id_t id) {
    return spl_type_def((spl_type_t *)&sema->type, id);
}

static spl_type_id_t underlying(const spl_sema_t *sema, spl_type_id_t tid) {
    spl_type_node_t *t = tn(sema, tid);
    return (t && t->kind == SPL_TYPE_ID) ? t->type_id : tid;
}

static int type_same(const spl_sema_t *sema, spl_type_id_t a, spl_type_id_t b) {
    if (a == b)
        return 1;
    a = underlying(sema, a);
    b = underlying(sema, b);
    if (a == b)
        return 1;
    spl_type_node_t *na = tn(sema, a);
    spl_type_node_t *nb = tn(sema, b);
    if (!na || !nb || na->kind != nb->kind)
        return 0;
    switch (na->kind) {
    case SPL_TYPE_INT:
        return na->int_type.bits == nb->int_type.bits &&
               na->int_type.is_signed == nb->int_type.is_signed;
    case SPL_TYPE_FLOAT:
        return na->float_type.bits == nb->float_type.bits;
    case SPL_TYPE_PTR:
        return type_same(sema, na->ptr_pointee, nb->ptr_pointee);
    case SPL_TYPE_SLICE:
        return type_same(sema, na->slice_element, nb->slice_element);
    case SPL_TYPE_RANGE:
        return type_same(sema, na->range_element, nb->range_element);
    case SPL_TYPE_ARRAY:
        return na->array_type.len == nb->array_type.len &&
               type_same(sema, na->array_type.element, nb->array_type.element);
    case SPL_TYPE_FN: {
        if (na->fn_type.params.size != nb->fn_type.params.size)
            return 0;
        for (usize i = 0; i < na->fn_type.params.size; i++)
            if (!type_same(sema, na->fn_type.params.data[i], nb->fn_type.params.data[i]))
                return 0;
        return type_same(sema, na->fn_type.ret, nb->fn_type.ret);
    }
    default:
        return 0;
    }
}

static int is_int_type(const spl_sema_t *sema, spl_type_id_t tid) {
    spl_type_node_t *t = tn(sema, underlying(sema, tid));
    return t && t->kind == SPL_TYPE_INT;
}
static int is_float_type(const spl_sema_t *sema, spl_type_id_t tid) {
    spl_type_node_t *t = tn(sema, underlying(sema, tid));
    return t && t->kind == SPL_TYPE_FLOAT;
}
static int is_num_type(const spl_sema_t *sema, spl_type_id_t tid) {
    spl_type_node_t *t = tn(sema, underlying(sema, tid));
    return t && (t->kind == SPL_TYPE_INT || t->kind == SPL_TYPE_FLOAT);
}
static int is_ptr_type(const spl_sema_t *sema, spl_type_id_t tid) {
    spl_type_node_t *t = tn(sema, underlying(sema, tid));
    return t && t->kind == SPL_TYPE_PTR;
}

/* ---- 符号解析 ---- */

static spl_type_id_t agg_field_tid_at(spl_ast2ir_t *a, spl_type_id_t agg_tid, isize idx);
static isize gdata_index_by_def(spl_ast2ir_t *a, spl_def_id_t def_id);

static spl_type_id_t kw_type(spl_ast2ir_t *a, const char *name) {
    spl_def_id_t def = 0;
    if (map_get(a->sema->scopes.data[a->sema->root_scope].symbols, name, &def)) {
        spl_def_node_t *d = def_at(a->sema, def);
        if (d)
            return d->type_id;
    }
    return 0;
}

static spl_def_id_t root_lookup(spl_ast2ir_t *a, const char *name) {
    spl_def_id_t def = 0;
    if (map_get(a->sema->scopes.data[a->sema->root_scope].symbols, name, &def))
        return def;
    return 0;
}

/* 匿名类型 id 拥有它的 def（聚合优先，别名/distinct 兜底*/
static spl_def_id_t def_for_type(spl_ast2ir_t *a, spl_type_id_t tid) {
    if (!tid)
        return 0;
    tid = underlying(a->sema, tid);
    spl_def_id_t fallback = 0;
    for (usize i = 1; i < a->sema->type.def_table.size; i++) {
        spl_def_node_t *d = &a->sema->type.def_table.data[i];
        spl_type_id_t dt = underlying(a->sema, d->type_id);
        if (dt == tid) {
            if (d->kind == SPL_DEF_AGG)
                return i;
            if (!fallback && (d->kind == SPL_DEF_ALIAS || d->kind == SPL_DEF_DISTINCT))
                fallback = i;
        }
    }
    return fallback;
}

/* 判断 agg_def 条目是否为结构字段（SPL_DEF_MEMBER<45>?*/
static int agg_entry_is_field(spl_ast2ir_t *a, const spl_var_def_t *e) {
    if (!e->def_id)
        return 0;
    spl_def_node_t *ed = def_at(a->sema, e->def_id);
    return ed && ed->kind == SPL_DEF_MEMBER;
}

/* 命名空间成员类型（方<EFBC88>?嵌套类型/static var）：按名任意 kind */
static spl_type_id_t agg_member_type(spl_ast2ir_t *a, spl_type_id_t agg_tid, const char *name) {
    agg_tid = underlying(a->sema, agg_tid);
    spl_def_id_t d = def_for_type(a, agg_tid);
    if (!d)
        return 0;
    spl_def_node_t *def = def_at(a->sema, d);
    for (usize i = 0; i < def->agg_def.size; i++) {
        if (def->agg_def.data[i].name && strcmp(def->agg_def.data[i].name, name) == 0)
            return def->agg_def.data[i].type_id;
    }
    return 0;
}

/* 结构字段序号 = 相对 SPL_DEF_MEMBER 的位置（<E7BDAE>?type.agg_field_types 按序对齐<E5AFB9>?*/
static isize agg_member_index(spl_ast2ir_t *a, spl_type_id_t agg_tid, const char *name) {
    agg_tid = underlying(a->sema, agg_tid);
    spl_def_id_t d = def_for_type(a, agg_tid);
    if (!d)
        return -1;
    spl_def_node_t *def = def_at(a->sema, d);
    isize fidx = 0;
    for (usize i = 0; i < def->agg_def.size; i++) {
        spl_var_def_t *e = &def->agg_def.data[i];
        int is_field = agg_entry_is_field(a, e);
        if (is_field && e->name && strcmp(e->name, name) == 0)
            return fidx;
        if (is_field)
            fidx++;
    }
    /* 字段访问只认结构字段（MEMBER_DECL）；var/fn/type 成员是命名空间实体，不在此列 */
    return -1;
}

static spl_type_id_t agg_field_tid_at(spl_ast2ir_t *a, spl_type_id_t agg_tid, isize idx) {
    spl_type_node_t *t = tn(a->sema, underlying(a->sema, agg_tid));
    if (!t || (t->kind != SPL_TYPE_STRUCT && t->kind != SPL_TYPE_UNION && t->kind != SPL_TYPE_ENUM))
        return 0;
    if (idx >= 0 && (usize)idx < t->agg_field_types.size)
        return t->agg_field_types.data[idx];
    if (t->kind == SPL_TYPE_ENUM && idx >= 0 && (usize)idx < t->enum_type.variants.size) {
        spl_type_id_t v = underlying(a->sema, t->enum_type.variants.data[idx]);
        return (v == underlying(a->sema, agg_tid)) ? 0 : v;
    }
    return 0;
}

/* 按字段序号查成员名（agg_def 中第 idx <20>?SPL_DEF_MEMBER 条目<E69DA1>?*/
static const char *agg_field_name_at(spl_ast2ir_t *a, spl_type_id_t agg_tid, isize idx) {
    agg_tid = underlying(a->sema, agg_tid);
    spl_def_id_t d = def_for_type(a, agg_tid);
    if (!d)
        return NULL;
    spl_def_node_t *def = def_at(a->sema, d);
    isize fidx = 0;
    for (usize i = 0; i < def->agg_def.size; i++) {
        spl_var_def_t *e = &def->agg_def.data[i];
        if (agg_entry_is_field(a, e)) {
            if (fidx == idx)
                return e->name;
            fidx++;
        }
    }
    return NULL;
}

/* 切片/区间内置字段（ptr/len/begin/end）并入成员查*/
static isize agg_index_or_builtin(spl_ast2ir_t *a, spl_type_id_t agg_tid, const char *name) {
    spl_type_node_t *t = tn(a->sema, underlying(a->sema, agg_tid));
    if (t && t->kind == SPL_TYPE_SLICE) {
        if (strcmp(name, "ptr") == 0)
            return 0;
        if (strcmp(name, "len") == 0)
            return 1;
    }
    if (t && t->kind == SPL_TYPE_RANGE) {
        if (strcmp(name, "begin") == 0)
            return 0;
        if (strcmp(name, "end") == 0)
            return 1;
    }
    return agg_member_index(a, agg_tid, name);
}

static spl_type_id_t agg_field_tid_or_builtin(spl_ast2ir_t *a, spl_type_id_t agg_tid, isize idx) {
    spl_type_node_t *t = tn(a->sema, underlying(a->sema, agg_tid));
    if (t && t->kind == SPL_TYPE_SLICE) {
        if (idx == 0)
            return spl_type_ptr((spl_type_t *)&a->sema->type, t->slice_element);
        if (idx == 1)
            return kw_type(a, "usize");
    }
    if (t && t->kind == SPL_TYPE_RANGE)
        return t->range_element;
    return agg_field_tid_at(a, agg_tid, idx);
}

/* ================================================================
 * IR 发射（per-function 上下文）
 * ================================================================ */

typedef struct {
    const char *name;
    spl_def_id_t def_id; /* 0 = 未知（名字兜底） */
    spl_type_id_t tid;
    spl_ir_node_ref_t slot;  /* 0 = 非内存绑*/
    spl_ir_node_ref_t value; /* SSA 值绑*/
    int is_type;
    int mut;
} ir_env_t;
typedef struct {
    VEC(ir_env_t) syms;
    VEC(spl_ast_node_ref_t) defers; /* 本作用域defer */
} ir_env_scope_t;
typedef VEC(ir_env_scope_t) ir_env_stack_t;

typedef struct {
    spl_ir_node_ref_t first;
} ir_block_t;
typedef VEC(ir_block_t) ir_block_vec_t;

typedef struct {
    spl_ir_node_ref_t node;
    int slot; /* 0=true_label 1=false_label 2=jmp.label */
    usize block;
} ir_fix_t;
typedef VEC(ir_fix_t) ir_fix_vec_t;

typedef struct {
    usize brk;
    usize cont;
    usize env_mark; /* 循环体作用域起始下标（defer 边界*/
} ir_loop_t;
typedef VEC(ir_loop_t) ir_loop_vec_t;

typedef struct {
    spl_ir_func_ref_t fn;
    spl_ast2ir_t *a;
    spl_type_id_t ret_tid;
    spl_type_id_t ns_tid; /* 所在聚合类型（方法命名空间）；顶层0 */
    ir_env_stack_t env;
    ir_block_vec_t blocks;
    usize cur_block;
    ir_fix_vec_t fixups;
    ir_loop_vec_t loops;
    VEC(spl_type_id_t) types; /* nodes 平行的结果类型表 */
    int terminated;
    spl_type_id_t hint;
    int err;
} fnctx_t;

static void fc_init(fnctx_t *fc, spl_ast2ir_t *a, spl_ir_func_ref_t fn, spl_type_id_t ret) {
    memset(fc, 0, sizeof *fc);
    fc->a = a;
    fc->fn = fn;
    fc->ret_tid = ret;
    vec_init(fc->env);
    vec_init(fc->blocks);
    vec_init(fc->fixups);
    vec_init(fc->loops);
    vec_init(fc->types);
}

static void fc_init_ns(fnctx_t *fc, spl_ast2ir_t *a, spl_ir_func_ref_t fn, spl_type_id_t ret,
                       spl_type_id_t ns) {
    fc_init(fc, a, fn, ret);
    fc->ns_tid = ns;
}

static void fc_drop(fnctx_t *fc) {
    for (usize i = 0; i < fc->env.size; i++) {
        vec_free(fc->env.data[i].syms);
        vec_free(fc->env.data[i].defers);
    }
    vec_free(fc->env);
    vec_free(fc->blocks);
    vec_free(fc->fixups);
    vec_free(fc->loops);
    vec_free(fc->types);
}

static void diag(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_t ref, const char *msg) {
    spl_ast_node_t *n = node_at(a->sema, ref);
    fc->err++;
    if (n)
        LOG_WARN("ast2ir: %s (%s:%d:%d)", msg, n->loc.fname ? n->loc.fname : "?", n->loc.line,
                 n->loc.col);
    else
        LOG_WARN("ast2ir: %s [fn=%s]", msg,
                 spl_ir_func(&a->ir, fc->fn)->name ? spl_ir_func(&a->ir, fc->fn)->name : "?");
}

static spl_ir_node_ref_t emit_node(spl_ast2ir_t *a, fnctx_t *fc) {
    if (fc->terminated) {
        ir_block_t b;
        memset(&b, 0, sizeof b);
        vec_push(fc->blocks, b);
        fc->cur_block = fc->blocks.size - 1;
        fc->terminated = 0;
    }
    spl_ir_node_ref_t r = spl_ir_alloc_node(&a->ir, fc->fn);
    if (fc->cur_block < fc->blocks.size && !fc->blocks.data[fc->cur_block].first)
        fc->blocks.data[fc->cur_block].first = r;
    if (fc->types.size == 0) {
        spl_type_id_t t0 = 0;
        vec_push(fc->types, t0);
    }
    spl_type_id_t t1 = 0;
    vec_push(fc->types, t1);
    return r;
}

static spl_ir_node_t *enode(spl_ast2ir_t *a, fnctx_t *fc, spl_ir_node_ref_t r) {
    return spl_ir_node(&a->ir, fc->fn, r);
}

static void set_ntype(fnctx_t *fc, spl_ir_node_ref_t r, spl_type_id_t tid) {
    if (r && r < fc->types.size)
        fc->types.data[r] = tid;
}

static spl_type_id_t node_type(fnctx_t *fc, spl_ir_node_ref_t r) {
    if (!r || r >= fc->types.size)
        return 0;
    return fc->types.data[r];
}

static usize new_block(fnctx_t *fc) {
    ir_block_t b;
    memset(&b, 0, sizeof b);
    vec_push(fc->blocks, b);
    return fc->blocks.size - 1;
}

static void begin_block(fnctx_t *fc, usize id) {
    fc->cur_block = id;
    fc->terminated = 0;
}

static void emit_jmp(spl_ast2ir_t *a, fnctx_t *fc, usize target) {
    spl_ir_node_ref_t r = emit_node(a, fc);
    spl_ir_node_t *n = enode(a, fc, r);
    n->kind = SPL_IR_CONTROL_JMP;
    n->control_jmp.label = 0;
    ir_fix_t f = {r, 2, target};
    vec_push(fc->fixups, f);
    fc->terminated = 1;
}

static void emit_br(spl_ast2ir_t *a, fnctx_t *fc, spl_ir_node_ref_t cond, usize t, usize f) {
    spl_ir_node_ref_t r = emit_node(a, fc);
    spl_ir_node_t *n = enode(a, fc, r);
    n->kind = SPL_IR_CONTROL_BR;
    n->control_br.cond = cond;
    n->control_br.true_label = 0;
    n->control_br.false_label = 0;
    ir_fix_t a1 = {r, 0, t};
    ir_fix_t a2 = {r, 1, f};
    vec_push(fc->fixups, a1);
    vec_push(fc->fixups, a2);
    fc->terminated = 1;
}

static void emit_ret(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t tid, spl_ir_node_ref_t val) {
    spl_ir_node_ref_t r = emit_node(a, fc);
    spl_ir_node_t *n = enode(a, fc, r);
    n->kind = SPL_IR_CONTROL_RET;
    n->control_ret.tid = tid;
    n->control_ret.val = val;
    fc->terminated = 1;
}

static spl_ir_node_ref_t emit_const(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t tid) {
    spl_ir_node_ref_t r = emit_node(a, fc);
    spl_ir_node_t *n = enode(a, fc, r);
    n->kind = SPL_IR_TYPE_CONST;
    n->type_const.tid = tid;
    set_ntype(fc, r, tid);
    return r;
}

static spl_ir_node_ref_t const_int(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t tid, usize v) {
    spl_ir_node_ref_t r = emit_const(a, fc, tid);
    enode(a, fc, r)->type_const.int_lit = v;
    return r;
}

static spl_ir_node_ref_t const_bool(spl_ast2ir_t *a, fnctx_t *fc, int v) {
    return const_int(a, fc, kw_type(a, "bool"), (usize)(v ? 1 : 0));
}

static spl_ir_node_ref_t const_float(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t tid, double v) {
    spl_ir_node_ref_t r = emit_const(a, fc, tid);
    enode(a, fc, r)->type_const.float_lit = v;
    return r;
}

static spl_ir_node_ref_t const_str(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t tid, const char *s) {
    spl_ir_node_ref_t r = emit_const(a, fc, tid);
    enode(a, fc, r)->type_const.cstr_lit = s;
    return r;
}

static spl_ir_node_ref_t const_fnref(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t fn_tid,
                                     spl_ir_func_ref_t fid) {
    spl_ir_node_ref_t r = emit_const(a, fc, fn_tid);
    enode(a, fc, r)->type_const.fn = fid;
    return r;
}

static spl_ir_node_ref_t emit_arith(spl_ast2ir_t *a, fnctx_t *fc, spl_ir_kind_t k,
                                    spl_type_id_t tid, spl_ir_node_ref_t l, spl_ir_node_ref_t r) {
    spl_ir_node_ref_t n = emit_node(a, fc);
    spl_ir_node_t *e = enode(a, fc, n);
    e->kind = k;
    e->arith.tid = tid;
    e->arith.left = l;
    e->arith.right = r;
    set_ntype(fc, n, tid);
    return n;
}

static spl_ir_node_ref_t emit_cmp(spl_ast2ir_t *a, fnctx_t *fc, spl_ir_kind_t k, spl_type_id_t tid,
                                  spl_ir_node_ref_t x, spl_ir_node_ref_t y) {
    spl_ir_node_ref_t n = emit_node(a, fc);
    spl_ir_node_t *e = enode(a, fc, n);
    e->kind = k;
    e->cmp.tid = tid;
    e->cmp.a = x;
    e->cmp.b = y;
    set_ntype(fc, n, kw_type(a, "bool"));
    return n;
}

static spl_ir_node_ref_t emit_cast(spl_ast2ir_t *a, fnctx_t *fc, spl_ir_kind_t k,
                                   spl_type_id_t from, spl_type_id_t to, spl_ir_node_ref_t v) {
    spl_ir_node_ref_t n = emit_node(a, fc);
    spl_ir_node_t *e = enode(a, fc, n);
    e->kind = k;
    e->cast.from_tid = from;
    e->cast.to_tid = to;
    e->cast.val = v;
    set_ntype(fc, n, to);
    return n;
}

static spl_ir_node_ref_t emit_alloca(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t tid) {
    spl_ir_node_ref_t cnt = const_int(a, fc, kw_type(a, "usize"), 1);
    spl_ir_node_ref_t n = emit_node(a, fc);
    spl_ir_node_t *e = enode(a, fc, n);
    e->kind = SPL_IR_MEM_ALLOCA;
    e->mem_alloc.tid = tid;
    e->mem_alloc.count = cnt;
    spl_type_id_t pt = spl_type_ptr((spl_type_t *)&a->sema->type, tid);
    set_ntype(fc, n, pt);
    return n;
}

static void emit_store(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t tid, spl_ir_node_ref_t ptr,
                       spl_ir_node_ref_t val) {
    spl_ir_node_ref_t n = emit_node(a, fc);
    spl_ir_node_t *e = enode(a, fc, n);
    e->kind = SPL_IR_MEM_STORE;
    e->mem_store.tid = tid;
    e->mem_store.ptr = ptr;
    e->mem_store.val = val;
}

static spl_ir_node_ref_t emit_load(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t tid,
                                   spl_ir_node_ref_t ptr) {
    spl_ir_node_ref_t n = emit_node(a, fc);
    spl_ir_node_t *e = enode(a, fc, n);
    e->kind = SPL_IR_MEM_LOAD;
    e->mem_load.tid = tid;
    e->mem_load.ptr = ptr;
    set_ntype(fc, n, tid);
    return n;
}

static spl_ir_node_ref_t emit_offset(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t tid,
                                     spl_ir_node_ref_t ptr, spl_ir_node_ref_t off) {
    spl_ir_node_ref_t n = emit_node(a, fc);
    spl_ir_node_t *e = enode(a, fc, n);
    e->kind = SPL_IR_MEM_OFFSET;
    e->mem_offset.tid = tid;
    e->mem_offset.ptr = ptr;
    e->mem_offset.offset = off;
    spl_type_id_t pt = spl_type_ptr((spl_type_t *)&a->sema->type, tid);
    set_ntype(fc, n, pt);
    return n;
}

/* 字段地址：mem.field_ptr(agg_tid, agg, idx) → *field_type。布局偏移由 ir2vm 算，ast2ir 不算。 */
static spl_ir_node_ref_t emit_field(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t agg_tid,
                                    spl_ir_node_ref_t ptr, isize fidx) {
    spl_type_id_t fty = agg_field_tid_or_builtin(a, agg_tid, fidx);
    spl_ir_node_ref_t n = emit_node(a, fc);
    spl_ir_node_t *e = enode(a, fc, n);
    e->kind = SPL_IR_MEM_FIELD_PTR;
    e->mem_field_ptr.tid = underlying(a->sema, agg_tid);
    e->mem_field_ptr.agg = ptr;
    e->mem_field_ptr.field_idx = (usize)fidx;
    spl_type_id_t pt = spl_type_ptr((spl_type_t *)&a->sema->type, fty);
    set_ntype(fc, n, pt);
    return n;
}

/* 全局静态数据地址：mem.global_alloc(tid, gdata_idx) <20>?*tid */
static spl_ir_node_ref_t emit_global_alloc(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t tid,
                                           usize gdata_idx) {
    spl_ir_node_ref_t n = emit_node(a, fc);
    spl_ir_node_t *e = enode(a, fc, n);
    e->kind = SPL_IR_MEM_GLOBAL_ALLOC;
    e->mem_global_alloc.tid = tid;
    e->mem_global_alloc.const_node = gdata_idx;
    spl_type_id_t pt = spl_type_ptr((spl_type_t *)&a->sema->type, tid);
    set_ntype(fc, n, pt);
    return n;
}

static spl_ir_node_ref_t emit_agg_construct(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t tid) {
    spl_ir_node_ref_t n = emit_node(a, fc);
    spl_ir_node_t *e = enode(a, fc, n);
    e->kind = SPL_IR_AGG_CONSTRUCT;
    e->agg_construct.tid = tid;
    vec_init(e->agg_construct.fields);
    set_ntype(fc, n, tid);
    return n;
}

static void agg_construct_add(spl_ast2ir_t *a, fnctx_t *fc, spl_ir_node_ref_t agg,
                              spl_ir_node_ref_t field) {
    spl_ir_node_t *e = enode(a, fc, agg);
    vec_push(e->agg_construct.fields, field);
}

static spl_ir_node_ref_t emit_agg_extract(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t tid,
                                          spl_type_id_t field_tid, isize fidx,
                                          spl_ir_node_ref_t val) {
    spl_ir_node_ref_t n = emit_node(a, fc);
    spl_ir_node_t *e = enode(a, fc, n);
    e->kind = SPL_IR_AGG_EXTRACT;
    e->agg_extract.tid = tid;
    e->agg_extract.field_tid = field_tid;
    e->agg_extract.field_idx = fidx;
    e->agg_extract.val = val;
    set_ntype(fc, n, field_tid);
    return n;
}

static spl_ir_node_ref_t emit_agg_insert(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t tid,
                                         isize fidx, spl_ir_node_ref_t agg,
                                         spl_ir_node_ref_t field) {
    spl_ir_node_ref_t n = emit_node(a, fc);
    spl_ir_node_t *e = enode(a, fc, n);
    e->kind = SPL_IR_AGG_INSERT;
    e->agg_insert.tid = tid;
    e->agg_insert.field_idx = fidx;
    e->agg_insert.agg = agg;
    e->agg_insert.field = field;
    set_ntype(fc, n, tid);
    return n;
}

static spl_ir_node_ref_t emit_call(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t fn_tid,
                                   spl_ir_node_ref_t callee, spl_ir_node_ref_t *args, usize nargs) {
    spl_ir_node_ref_t n = emit_node(a, fc);
    spl_ir_node_t *e = enode(a, fc, n);
    e->kind = SPL_IR_CONTROL_CALL;
    e->control_call.tid = fn_tid;
    e->control_call.func = callee;
    vec_init(e->control_call.params);
    for (usize i = 0; i < nargs; i++)
        vec_push(e->control_call.params, args[i]);
    spl_type_node_t *ft = tn(a->sema, fn_tid);
    spl_type_id_t ret = (ft && ft->kind == SPL_TYPE_FN) ? ft->fn_type.ret : 0;
    set_ntype(fc, n, ret);
    return n;
}

static spl_ir_node_ref_t emit_select(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t tid,
                                     spl_ir_node_ref_t c, spl_ir_node_ref_t t,
                                     spl_ir_node_ref_t f) {
    spl_ir_node_ref_t n = emit_node(a, fc);
    spl_ir_node_t *e = enode(a, fc, n);
    e->kind = SPL_IR_CONTROL_SELECT;
    e->control_select.tid = tid;
    e->control_select.cond = c;
    e->control_select.true_val = t;
    e->control_select.false_val = f;
    set_ntype(fc, n, tid);
    return n;
}

/* ================================================================
 * 环境（变类型绑定 * ================================================================ */

static void env_push(fnctx_t *fc) {
    ir_env_scope_t s;
    memset(&s, 0, sizeof s);
    vec_init(s.syms);
    vec_init(s.defers);
    vec_push(fc->env, s);
}

static void env_pop(fnctx_t *fc) {
    if (!fc->env.size)
        return;
    vec_free(fc->env.data[fc->env.size - 1].syms);
    vec_free(fc->env.data[fc->env.size - 1].defers);
    vec_pop(fc->env);
}

static ir_env_t *env_find(fnctx_t *fc, const char *name) {
    for (usize i = fc->env.size; i > 0; i--) {
        ir_env_scope_t *s = &fc->env.data[i - 1];
        for (usize j = 0; j < s->syms.size; j++) {
            if (s->syms.data[j].name && strcmp(s->syms.data[j].name, name) == 0)
                return &s->syms.data[j];
        }
    }
    return NULL;
}

/* def_id 优先定位（sema 已作用域解析，绕开同名遮蔽歧义）；<EFBC89>?def_id 时兜底名<E5BA95>?*/
static ir_env_t *env_find_def(fnctx_t *fc, spl_def_id_t def_id, const char *name) {
    if (def_id) {
        for (usize i = fc->env.size; i > 0; i--) {
            ir_env_scope_t *s = &fc->env.data[i - 1];
            for (usize j = 0; j < s->syms.size; j++) {
                if (s->syms.data[j].def_id == def_id)
                    return &s->syms.data[j];
            }
        }
    }
    return name ? env_find(fc, name) : NULL;
}

static void env_add(fnctx_t *fc, const char *name, spl_def_id_t def_id, spl_type_id_t tid,
                    spl_ir_node_ref_t slot, spl_ir_node_ref_t value, int is_type, int mut) {
    if (!fc->env.size)
        env_push(fc);
    ir_env_t it;
    memset(&it, 0, sizeof it);
    it.name = name;
    it.def_id = def_id;
    it.tid = tid;
    it.slot = slot;
    it.value = value;
    it.is_type = is_type;
    it.mut = mut;
    vec_push(fc->env.data[fc->env.size - 1].syms, it);
}

/* ================================================================
 * 枚举
 * ================================================================ */

static spl_type_id_t enum_tag_tid(spl_ast2ir_t *a) { return kw_type(a, "usize"); }

static isize enum_variant_index(spl_ast2ir_t *a, spl_type_id_t enum_tid, const char *name) {
    enum_tid = underlying(a->sema, enum_tid);
    spl_def_id_t d = def_for_type(a, enum_tid);
    if (!d)
        return -1;
    spl_def_node_t *def = def_at(a->sema, d);
    isize vidx = 0;
    for (usize i = 0; i < def->agg_def.size; i++) {
        spl_var_def_t *e = &def->agg_def.data[i];
        if (agg_entry_is_field(a, e)) {
            if (e->name && strcmp(e->name, name) == 0)
                return vidx;
            vidx++;
        }
    }
    return -1;
}

static spl_type_id_t enum_payload_tid(spl_ast2ir_t *a, spl_type_id_t enum_tid, isize idx) {
    enum_tid = underlying(a->sema, enum_tid);
    spl_type_node_t *t = tn(a->sema, enum_tid);
    if (!t || t->kind != SPL_TYPE_ENUM || idx < 0 || (usize)idx >= t->enum_type.variants.size)
        return 0;
    spl_type_id_t v = underlying(a->sema, t->enum_type.variants.data[idx]);
    return (v == enum_tid) ? 0 : v;
}

static spl_ir_node_ref_t enum_variant_value(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t enum_tid,
                                            isize idx) {
    spl_ir_node_ref_t agg = emit_agg_construct(a, fc, enum_tid);
    agg_construct_add(a, fc, agg, const_int(a, fc, enum_tag_tid(a), (usize)idx));
    return agg;
}

static spl_ir_node_ref_t enum_tag_of(spl_ast2ir_t *a, fnctx_t *fc, spl_type_id_t enum_tid,
                                     spl_ir_node_ref_t val) {
    return emit_agg_extract(a, fc, enum_tid, enum_tag_tid(a), 0, val);
}

/* tid 是否<E698AF>?enum */
static int is_enum_expand(spl_ast2ir_t *a, spl_type_id_t tid, spl_type_id_t *out_enum) {
    spl_type_node_t *t = tn(a->sema, underlying(a->sema, tid));
    if (t && t->kind == SPL_TYPE_ENUM) {
        if (out_enum)
            *out_enum = underlying(a->sema, tid);
        return 1;
    }
    return 0;
}

/* 表达式当作类型引用解析（a / a.b.c，用于枚举变嵌套类型路径*/
static spl_type_id_t type_of_type_ref(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_t bref) {
    spl_ast_node_t *n = node_at(a->sema, bref);
    if (!n || n->kind != SPL_AST_EXPR)
        return 0;
    if (n->expr.op == SPL_AST_PRIMARY_EXPR) {
        spl_ast_node_t *pn = node_at(a->sema, n->expr.op_expr.left);
        if (pn && pn->primary_expr.kind == SPL_AST_IDENT) {
            ir_env_t *it = env_find_def(fc, pn->resolved_def_id, pn->primary_expr.ident);
            if (it && it->is_type)
                return underlying(a->sema, it->tid);
            spl_def_id_t def = root_lookup(a, pn->primary_expr.ident);
            if (def) {
                spl_def_node_t *d = def_at(a->sema, def);
                if (d && d->type_id)
                    return underlying(a->sema, d->type_id);
            }
        }
        return 0;
    }
    if (n->expr.op == SPL_AST_POSTFIX_EXPR) {
        spl_ast_node_t *pf = node_at(a->sema, n->expr.op_expr.left);
        if (pf && pf->postfix_expr.kind == SPL_AST_FIELD_EXPR) {
            spl_type_id_t bt = type_of_type_ref(a, fc, pf->postfix_expr.primary_expr);
            if (bt) {
                spl_type_id_t mt = agg_member_type(a, bt, pf->postfix_expr.field_expr);
                return underlying(a->sema, mt);
            }
        }
        return 0;
    }
    return 0;
}

/* ================================================================
 * 类型解析（自包含 * ================================================================ */

static spl_type_id_t resolve_type_expr(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_t ref);

static spl_type_id_t resolve_type_atom(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_t ref) {
    spl_ast_node_t *n = node_at(a->sema, ref);
    if (!n)
        return 0;
    switch (n->type_atom.kind) {
    case SPL_AST_TYPE_VOID:
        return kw_type(a, "void");
    case SPL_AST_TYPE_BOOL:
        return kw_type(a, "bool");
    case SPL_AST_TYPE_I8:
        return kw_type(a, "i8");
    case SPL_AST_TYPE_U8:
        return kw_type(a, "u8");
    case SPL_AST_TYPE_I16:
        return kw_type(a, "i16");
    case SPL_AST_TYPE_U16:
        return kw_type(a, "u16");
    case SPL_AST_TYPE_I32:
        return kw_type(a, "i32");
    case SPL_AST_TYPE_U32:
        return kw_type(a, "u32");
    case SPL_AST_TYPE_I64:
        return kw_type(a, "i64");
    case SPL_AST_TYPE_U64:
        return kw_type(a, "u64");
    case SPL_AST_TYPE_ISIZE:
        return kw_type(a, "isize");
    case SPL_AST_TYPE_USIZE:
        return kw_type(a, "usize");
    case SPL_AST_TYPE__F32:
        return kw_type(a, "f32");
    case SPL_AST_TYPE__F64:
        return kw_type(a, "f64");
    case SPL_AST_TYPE_PTR:
    case SPL_AST_TYPE_ANY:
        return kw_type(a, "void");
    case SPL_AST_TYPE_IDENT: {
        const char *name = n->type_atom.ident;
        ir_env_t *it = env_find(fc, name);
        if (it && it->is_type)
            return it->tid;
        spl_def_id_t def = root_lookup(a, name);
        if (def) {
            spl_def_node_t *d = def_at(a->sema, def);
            if (d && d->type_id)
                return d->type_id;
        }
        return 0;
    }
    }
    return 0;
}

static spl_type_id_t resolve_type_path(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_vec_t *path) {
    if (!path->size)
        return 0;
    spl_type_id_t tid = resolve_type_atom(a, fc, path->data[0]);
    if (!tid)
        return 0;
    for (usize i = 1; i < path->size; i++) {
        spl_ast_node_t *atom = node_at(a->sema, path->data[i]);
        if (!atom)
            return 0;
        spl_type_id_t mt = agg_member_type(a, tid, atom->type_atom.ident);
        if (!mt)
            return 0;
        tid = mt;
    }
    return tid;
}

static spl_type_id_t resolve_type_expr(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_t ref) {
    spl_ast_node_t *n = node_at(a->sema, ref);
    if (!n)
        return 0;
    /* 首<>?sema 注解：resolved_def_id <20>?def <20>?类型（聚<EFBC88>?别名/命名类型<E7B1BB>?*/
    if (n->resolved_def_id) {
        spl_def_node_t *d = def_at(a->sema, n->resolved_def_id);
        if (d && d->type_id)
            return d->type_id;
    }
    /* 兜底：组<EFBC9A>?内置类型（sema 不为其建 def <20>?*T、[]T、fn(...)、关键字、别名到组合<E7BB84>?*/
    spl_type_id_t base = 0;
    switch (n->type_expr.kind) {
    case SPL_AST_BASE_TYPE_PATH:
        base = resolve_type_path(a, fc, &n->type_expr.type_path);
        break;
    case SPL_AST_BASE_TYPE_FN: {
        spl_type_id_vec_t params;
        vec_init(params);
        for (usize i = 0; i < n->type_expr.fn_type.param_list.size; i++) {
            spl_ast_node_t *pd = node_at(a->sema, n->type_expr.fn_type.param_list.data[i]);
            spl_type_id_t pt = 0;
            if (pd && pd->param_decl.type_expr)
                pt = resolve_type_expr(a, fc, pd->param_decl.type_expr);
            vec_push(params, pt);
        }
        spl_type_id_t ret = 0;
        if (n->type_expr.fn_type.type_expr)
            ret = resolve_type_expr(a, fc, n->type_expr.fn_type.type_expr);
        else
            ret = kw_type(a, "void");
        base = spl_type_fn((spl_type_t *)&a->sema->type, params, ret);
        break;
    }
    case SPL_AST_TYPE_STRUCT:
    case SPL_AST_TYPE_UNION:
    case SPL_AST_TYPE_ENUM:
        /* 内联聚合不应走到这里（sema 已注解其 def）；防御性报<E680A7>?*/
        diag(a, fc, ref, "inline aggregate not annotated by sema");
        return 0;
    default:
        return 0;
    }
    for (usize i = n->type_expr.type_prefixs.size; i > 0; i--) {
        spl_ast_node_t *pf = node_at(a->sema, n->type_expr.type_prefixs.data[i - 1]);
        if (!pf)
            continue;
        if (pf->prefix_type.pointer == 1)
            base = spl_type_ptr((spl_type_t *)&a->sema->type, base);
        else if (pf->prefix_type.pointer == 2) {
            if (pf->prefix_type.array_size > 0)
                base = spl_type_array((spl_type_t *)&a->sema->type, base,
                                      (usize)pf->prefix_type.array_size);
            else
                base = spl_type_slice((spl_type_t *)&a->sema->type, base);
        }
    }
    return base;
}

/* ================================================================
 * 表达 * ================================================================ */

static spl_ir_node_ref_t lower_expr(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_t ref);
static void lower_stmt(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_t ref);
static void emit_scope_defers(spl_ast2ir_t *a, fnctx_t *fc, usize scope_idx);
static void emit_defers_from(spl_ast2ir_t *a, fnctx_t *fc, usize mark);
static spl_ir_func_ref_t a2ir_fn_of(spl_ast2ir_t *a, spl_type_id_t fn_tid);
static spl_ir_node_ref_t lower_compound_op(spl_ast2ir_t *a, fnctx_t *fc, int op, spl_type_id_t tid,
                                           spl_ir_node_ref_t cur, spl_ir_node_ref_t rhs);

static int expr_is_int_literal(spl_ast2ir_t *a, spl_ast_node_ref_t ref) {
    spl_ast_node_t *n = node_at(a->sema, ref);
    if (!n || n->kind != SPL_AST_EXPR)
        return 0;
    switch (n->expr.op) {
    case SPL_AST_PRIMARY_EXPR: {
        spl_ast_node_t *pn = node_at(a->sema, n->expr.op_expr.left);
        return pn && pn->primary_expr.kind == SPL_AST_INTEGER;
    }
    case SPL_AST_PREFIX_EXPR: {
        spl_ast_node_t *pf = node_at(a->sema, n->expr.op_expr.left);
        if (pf && pf->prefix_expr.kind == SPL_AST_MINUS_EXPR)
            return expr_is_int_literal(a, pf->prefix_expr.postfix_expr);
        return 0;
    }
    default:
        return 0;
    }
}

static spl_ir_node_ref_t coerce_to(spl_ast2ir_t *a, fnctx_t *fc, spl_ir_node_ref_t v,
                                   spl_type_id_t from, spl_type_id_t to) {
    if (!v || !from || !to)
        return v;
    if (type_same(a->sema, from, to))
        return v;
    spl_type_id_t f = underlying(a->sema, from);
    spl_type_id_t t = underlying(a->sema, to);
    spl_type_node_t *ft = tn(a->sema, f);
    spl_type_node_t *tt = tn(a->sema, t);
    if (!ft || !tt)
        return v;
    if (ft->kind == SPL_TYPE_INT && tt->kind == SPL_TYPE_INT) {
        if (ft->int_type.bits == tt->int_type.bits)
            return v;
        if (tt->int_type.bits > ft->int_type.bits)
            return emit_cast(a, fc, ft->int_type.is_signed ? SPL_IR_CAST_SEXT : SPL_IR_CAST_ZEXT,
                             from, to, v);
        return emit_cast(a, fc, SPL_IR_CAST_TRUNC, from, to, v);
    }
    if (ft->kind == SPL_TYPE_INT && tt->kind == SPL_TYPE_FLOAT)
        return emit_cast(a, fc, SPL_IR_CASE_INT2FLOAT, from, to, v);
    if (ft->kind == SPL_TYPE_FLOAT && tt->kind == SPL_TYPE_INT)
        return emit_cast(a, fc, SPL_IR_CASE_FLOAT2INT, from, to, v);
    if (ft->kind == SPL_TYPE_FLOAT && tt->kind == SPL_TYPE_FLOAT)
        return emit_cast(a, fc,
                         tt->float_type.bits > ft->float_type.bits ? SPL_IR_CAST_FEXT
                                                                   : SPL_IR_CAST_FTRUNC,
                         from, to, v);
    if (ft->kind == SPL_TYPE_PTR && tt->kind == SPL_TYPE_PTR)
        return emit_cast(a, fc, SPL_IR_CAST_BITCAST, from, to, v);
    if (ft->kind == SPL_TYPE_PTR && tt->kind == SPL_TYPE_INT)
        return emit_cast(a, fc, SPL_IR_CAST_PTR2INT, from, to, v);
    if (ft->kind == SPL_TYPE_INT && tt->kind == SPL_TYPE_PTR)
        return emit_cast(a, fc, SPL_IR_CAST_INT2PTR, from, to, v);
    if (ft->kind == SPL_TYPE_BOOL && tt->kind == SPL_TYPE_INT)
        return emit_cast(a, fc, SPL_IR_CAST_BOOL2INT, from, to, v);
    return v;
}

/* ---- 左值地址 ---- */

#define MAX_FIELD_CHAIN 16

static spl_ir_node_ref_t lower_lvalue(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_t ref,
                                      spl_type_id_t *out_tid);

/* 收集字段链（叶子在前）：返回EXPR ref */
static spl_ast_node_ref_t field_chain_base(spl_ast2ir_t *a, spl_ast_node_t *pf, const char **names,
                                           int *n) {
    *n = 0;
    names[(*n)++] = pf->postfix_expr.field_expr;
    spl_ast_node_ref_t bref = pf->postfix_expr.primary_expr;
    spl_ast_node_t *base = node_at(a->sema, bref);
    while (base && base->kind == SPL_AST_EXPR && base->expr.op == SPL_AST_POSTFIX_EXPR) {
        spl_ast_node_t *bpf = node_at(a->sema, base->expr.op_expr.left);
        if (!bpf || bpf->postfix_expr.kind != SPL_AST_FIELD_EXPR)
            break;
        if (*n >= MAX_FIELD_CHAIN)
            break;
        names[(*n)++] = bpf->postfix_expr.field_expr;
        bref = bpf->postfix_expr.primary_expr;
        base = node_at(a->sema, bref);
    }
    return bref;
}

/* 字段链的存储地址（root.a.b 地址 + 字段类型<E7B1BB>?*/
static spl_ir_node_ref_t lower_field_address(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_t bref,
                                             spl_type_id_t *out_tid) {
    spl_ast_node_t *n = node_at(a->sema, bref);
    if (!n || n->kind != SPL_AST_EXPR || n->expr.op != SPL_AST_POSTFIX_EXPR)
        return 0;
    spl_ast_node_t *pf = node_at(a->sema, n->expr.op_expr.left);
    if (!pf || pf->postfix_expr.kind != SPL_AST_FIELD_EXPR)
        return 0;
    const char *names[MAX_FIELD_CHAIN];
    int nf = 0;
    spl_ast_node_ref_t root_ref = field_chain_base(a, pf, names, &nf);
    /* 类型命名空间基址：Foo.counter（全局 var/const <20>?lvalue = <20>?gdata 地址<E59CB0>?*/
    spl_type_id_t ns = type_of_type_ref(a, fc, root_ref);
    if (ns && nf == 1) {
        spl_def_id_t gdef = def_for_type(a, ns);
        spl_def_node_t *gd = gdef ? def_at(a->sema, gdef) : NULL;
        for (usize i = 0; gd && i < gd->agg_def.size; i++) {
            spl_var_def_t *e = &gd->agg_def.data[i];
            if (e->name && strcmp(e->name, names[0]) == 0 && e->def_id) {
                spl_def_node_t *ed = def_at(a->sema, e->def_id);
                if (ed && ed->kind == SPL_DEF_VAR) {
                    isize gi = gdata_index_by_def(a, e->def_id);
                    if (gi >= 0) {
                        *out_tid = e->type_id;
                        return emit_global_alloc(a, fc, e->type_id, (usize)gi);
                    }
                }
                break;
            }
        }
        return 0;
    }
    spl_type_id_t cur_tid = 0;
    spl_ir_node_ref_t addr = lower_lvalue(a, fc, root_ref, &cur_tid);
    spl_type_node_t *curt = tn(a->sema, underlying(a->sema, cur_tid));
    if (curt && curt->kind == SPL_TYPE_PTR) {
        cur_tid = underlying(a->sema, curt->ptr_pointee);
        spl_type_id_t pty = spl_type_ptr((spl_type_t *)&a->sema->type, cur_tid);
        addr = emit_load(a, fc, pty, addr);
    }
    if (!addr || !cur_tid)
        return 0;
    for (int i = nf - 1; i >= 0; i--) {
        spl_type_node_t *ct = tn(a->sema, underlying(a->sema, cur_tid));
        if (!ct || (ct->kind != SPL_TYPE_STRUCT && ct->kind != SPL_TYPE_UNION &&
                    ct->kind != SPL_TYPE_SLICE && ct->kind != SPL_TYPE_RANGE))
            return 0;
        isize idx = agg_index_or_builtin(a, cur_tid, names[i]);
        if (idx < 0)
            return 0;
        spl_type_id_t ft = agg_field_tid_or_builtin(a, cur_tid, idx);
        addr = emit_field(a, fc, cur_tid, addr, idx);
        cur_tid = ft;
        if (i > 0) {
            spl_type_node_t *ftt = tn(a->sema, underlying(a->sema, cur_tid));
            if (ftt && ftt->kind == SPL_TYPE_PTR) {
                cur_tid = underlying(a->sema, ftt->ptr_pointee);
                spl_type_id_t pty = spl_type_ptr((spl_type_t *)&a->sema->type, cur_tid);
                addr = emit_load(a, fc, pty, addr);
            }
        }
    }
    *out_tid = cur_tid;
    return addr;
}

/* a[i] 内联 postfix 节点 元素地址 */
static spl_ir_node_ref_t index_addr(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_t *pf,
                                    spl_type_id_t *elem) {
    spl_ir_node_ref_t idx = lower_expr(a, fc, pf->postfix_expr.index_expr);
    spl_ast_node_ref_t bref = pf->postfix_expr.primary_expr;
    spl_type_id_t base_t = 0;
    spl_ir_node_ref_t base_lv = lower_lvalue(a, fc, bref, &base_t);
    spl_ir_node_ref_t base_addr = 0;
    spl_type_id_t elem_t = 0;
    spl_type_node_t *bt = NULL;
    if (base_lv) {
        bt = tn(a->sema, underlying(a->sema, base_t));
    } else {
        spl_ir_node_ref_t v = lower_expr(a, fc, bref);
        spl_type_id_t vt = underlying(a->sema, node_type(fc, v));
        spl_type_node_t *vtt = vt ? tn(a->sema, vt) : NULL;
        if (vtt && vtt->kind == SPL_TYPE_PTR) {
            base_addr = v;
            base_t = vt;
            bt = vtt;
        } else if (vtt && vtt->kind == SPL_TYPE_SLICE) {
            spl_type_id_t ep = spl_type_ptr((spl_type_t *)&a->sema->type, vtt->slice_element);
            base_addr = emit_agg_extract(a, fc, vt, ep, 0, v);
            base_t = vt;
            bt = vtt;
        } else if (vtt && vtt->kind == SPL_TYPE_ARRAY) {
            spl_type_id_t fat = 0;
            spl_ir_node_ref_t faddr = lower_field_address(a, fc, bref, &fat);
            if (faddr) {
                base_addr = faddr;
                base_t = fat;
                bt = tn(a->sema, underlying(a->sema, fat));
            } else {
                diag(a, fc, 0, "index on non-addressable array value");
                return 0;
            }
        } else {
            diag(a, fc, 0, "index requires array/slice/pointer");
            return 0;
        }
    }
    if (bt && bt->kind == SPL_TYPE_ARRAY) {
        base_addr = base_lv ? base_lv : base_addr;
        elem_t = bt->array_type.element;
    } else if (bt && bt->kind == SPL_TYPE_PTR) {
        base_addr = base_lv ? emit_load(a, fc, base_t, base_lv) : base_addr;
        elem_t = underlying(a->sema, bt->ptr_pointee);
    } else if (bt && bt->kind == SPL_TYPE_SLICE) {
        spl_ir_node_ref_t slv = base_lv ? emit_load(a, fc, base_t, base_lv) : base_addr;
        elem_t = bt->slice_element;
        spl_type_id_t ep = spl_type_ptr((spl_type_t *)&a->sema->type, elem_t);
        base_addr = emit_agg_extract(a, fc, base_t, ep, 0, slv);
    } else {
        diag(a, fc, 0, "index requires array/slice/pointer");
        return 0;
    }
    if (!elem_t) {
        diag(a, fc, 0, "index requires array/slice/pointer");
        return 0;
    }
    spl_ir_node_ref_t o = coerce_to(a, fc, idx, node_type(fc, idx), kw_type(a, "isize"));
    spl_ir_node_ref_t addr = emit_offset(a, fc, elem_t, base_addr, o);
    *elem = elem_t;
    return addr;
}

static spl_ir_node_ref_t lower_lvalue(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_t ref,
                                      spl_type_id_t *out_tid) {
    spl_ast_node_t *n = node_at(a->sema, ref);
    if (!n || n->kind != SPL_AST_EXPR)
        return 0;
    if (n->expr.op == SPL_AST_PRIMARY_EXPR) {
        spl_ast_node_t *pn = node_at(a->sema, n->expr.op_expr.left);
        if (pn && pn->primary_expr.kind == SPL_AST_IDENT) {
            ir_env_t *it = env_find_def(fc, pn->resolved_def_id, pn->primary_expr.ident);
            if (it && it->slot) {
                *out_tid = it->tid;
                return it->slot;
            }
            if (it) {
                diag(a, fc, ref, "not an addressable variable");
                return 0;
            }
            /* 顶层 / 命名空间全局 var：lvalue = 全局分配地址 */
            spl_def_id_t def = pn->resolved_def_id;
            if (!def)
                def = root_lookup(a, pn->primary_expr.ident);
            if (def) {
                spl_def_node_t *d = def_at(a->sema, def);
                if (d && d->kind == SPL_DEF_VAR) {
                    isize gi = gdata_index_by_def(a, def);
                    if (gi >= 0) {
                        *out_tid = d->type_id;
                        return emit_global_alloc(a, fc, *out_tid, (usize)gi);
                    }
                }
                if (fc->ns_tid) {
                    spl_def_id_t gdef = def_for_type(a, fc->ns_tid);
                    spl_def_node_t *gd = gdef ? def_at(a->sema, gdef) : NULL;
                    for (usize i = 0; gd && i < gd->agg_def.size; i++) {
                        spl_var_def_t *e = &gd->agg_def.data[i];
                        if (e->name && strcmp(e->name, pn->primary_expr.ident) == 0 && e->def_id) {
                            spl_def_node_t *ed = def_at(a->sema, e->def_id);
                            if (ed && ed->kind == SPL_DEF_VAR) {
                                isize gi = gdata_index_by_def(a, e->def_id);
                                if (gi >= 0) {
                                    *out_tid = e->type_id;
                                    return emit_global_alloc(a, fc, e->type_id, (usize)gi);
                                }
                            }
                            break;
                        }
                    }
                }
            }
            return 0;
        }
        if (pn && pn->primary_expr.kind == SPL_AST_EXPR_EXPR)
            return lower_lvalue(a, fc, pn->primary_expr.expr, out_tid);
        return 0;
    }
    if (n->expr.op == SPL_AST_POSTFIX_EXPR) {
        spl_ast_node_t *pf = node_at(a->sema, n->expr.op_expr.left);
        if (!pf)
            return 0;
        if (pf->postfix_expr.kind == SPL_AST_DEREF_EXPR) {
            spl_ir_node_ref_t p = lower_expr(a, fc, pf->postfix_expr.primary_expr);
            spl_type_id_t pt = underlying(a->sema, node_type(fc, p));
            spl_type_node_t *tt = tn(a->sema, pt);
            if (!tt || tt->kind != SPL_TYPE_PTR) {
                diag(a, fc, ref, ".* requires pointer");
                return 0;
            }
            *out_tid = underlying(a->sema, tt->ptr_pointee);
            return p;
        }
        if (pf->postfix_expr.kind == SPL_AST_INDEX_EXPR)
            return index_addr(a, fc, pf, out_tid);
        if (pf->postfix_expr.kind == SPL_AST_FIELD_EXPR)
            return lower_field_address(a, fc, ref, out_tid);
        return 0;
    }
    if (n->expr.op == SPL_AST_PREFIX_EXPR) {
        spl_ast_node_t *pp = node_at(a->sema, n->expr.op_expr.left);
        if (pp && pp->prefix_expr.kind == SPL_AST_ASTERISK_EXPR) {
            spl_ir_node_ref_t p = lower_expr(a, fc, pp->prefix_expr.postfix_expr);
            spl_type_id_t pt = underlying(a->sema, node_type(fc, p));
            spl_type_node_t *tt = tn(a->sema, pt);
            if (!tt || tt->kind != SPL_TYPE_PTR) {
                diag(a, fc, ref, "prefix * requires pointer");
                return 0;
            }
            *out_tid = underlying(a->sema, tt->ptr_pointee);
            return p;
        }
        return 0;
    }
    return 0;
}

static spl_ir_node_ref_t lower_ident(spl_ast2ir_t *a, fnctx_t *fc, const char *name,
                                     spl_def_id_t def_id, spl_ast_node_ref_t ref) {
    ir_env_t *it = env_find_def(fc, def_id, name);
    if (it) {
        if (it->is_type) {
            diag(a, fc, ref, "type used as value");
            return 0;
        }
        if (it->slot)
            return emit_load(a, fc, it->tid, it->slot);
        return it->value;
    }
    spl_def_id_t def = root_lookup(a, name);
    if (def) {
        spl_def_node_t *d = def_at(a->sema, def);
        if (d &&
            (d->kind == SPL_DEF_AGG || d->kind == SPL_DEF_ALIAS || d->kind == SPL_DEF_DISTINCT)) {
            diag(a, fc, ref, "type name used as value");
            return 0;
        }
        if (d && d->kind == SPL_DEF_VAR) {
            isize gi = gdata_index_by_def(a, def);
            if (gi >= 0)
                return emit_load(a, fc, d->type_id,
                                 emit_global_alloc(a, fc, d->type_id, (usize)gi));
        }
        diag(a, fc, ref, "undefined identifier");
    } else {
        /* 命名空间内裸名：fc->ns_tid 聚合成员 static var/const */
        if (fc->ns_tid) {
            spl_def_id_t gdef = def_for_type(a, fc->ns_tid);
            spl_def_node_t *gd = gdef ? def_at(a->sema, gdef) : NULL;
            for (usize i = 0; gd && i < gd->agg_def.size; i++) {
                spl_var_def_t *e = &gd->agg_def.data[i];
                if (e->name && strcmp(e->name, name) == 0 && e->def_id) {
                    spl_def_node_t *ed = def_at(a->sema, e->def_id);
                    if (ed && ed->kind == SPL_DEF_VAR) {
                        isize gi = gdata_index_by_def(a, e->def_id);
                        if (gi >= 0)
                            return emit_load(a, fc, e->type_id,
                                             emit_global_alloc(a, fc, e->type_id, (usize)gi));
                    }
                    break;
                }
            }
        }
        diag(a, fc, ref, "undefined identifier");
    }
    return 0;
}

static spl_type_id_t type_from_type_like(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_t ref) {
    spl_ast_node_t *n = node_at(a->sema, ref);
    if (!n || n->kind != SPL_AST_EXPR)
        return 0;
    if (n->expr.op != SPL_AST_PRIMARY_EXPR)
        return 0;
    spl_ast_node_t *pn = node_at(a->sema, n->expr.op_expr.left);
    if (!pn || pn->primary_expr.kind != SPL_AST_IDENT)
        return 0;
    ir_env_t *it = env_find_def(fc, pn->resolved_def_id, pn->primary_expr.ident);
    if (it && it->is_type)
        return it->tid;
    spl_def_id_t def = root_lookup(a, pn->primary_expr.ident);
    if (def) {
        spl_def_node_t *d = def_at(a->sema, def);
        if (d && d->type_id)
            return d->type_id;
    }
    return 0;
}

static spl_ir_node_ref_t lower_block_expr(spl_ast2ir_t *a, fnctx_t *fc,
                                          spl_ast_node_ref_vec_t *items) {
    env_push(fc);
    spl_ir_node_ref_t result = 0;
    for (usize i = 0; i < items->size; i++) {
        spl_ast_node_t *b = node_at(a->sema, items->data[i]);
        if (i + 1 == items->size && b && b->kind == SPL_AST_EXPR) {
            spl_ir_node_ref_t v = lower_expr(a, fc, items->data[i]);
            if (v && !fc->terminated)
                result = v;
            break;
        }
        lower_stmt(a, fc, items->data[i]);
    }
    if (!fc->terminated)
        emit_scope_defers(a, fc, fc->env.size - 1);
    env_pop(fc);
    return result;
}

static spl_ir_node_ref_t lower_primary(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_t *pn) {
    switch (pn->primary_expr.kind) {
    case SPL_AST_INTEGER: {
        spl_type_id_t t = kw_type(a, "i32");
        if (fc->hint && is_int_type(a->sema, fc->hint))
            t = underlying(a->sema, fc->hint);
        return const_int(a, fc, t, (usize)pn->primary_expr.integer_expr);
    }
    case SPL_AST_FLOAT: {
        spl_type_id_t t = kw_type(a, "f64");
        if (fc->hint && is_float_type(a->sema, fc->hint))
            t = underlying(a->sema, fc->hint);
        return const_float(a, fc, t, pn->primary_expr.float_expr);
    }
    case SPL_AST_CHAR_LIT: {
        spl_type_id_t t = kw_type(a, "u8");
        if (fc->hint && is_int_type(a->sema, fc->hint))
            t = underlying(a->sema, fc->hint);
        return const_int(a, fc, t, (usize)(unsigned char)pn->primary_expr.char_lit_expr);
    }
    case SPL_AST_STRING_LIT: {
        spl_type_id_t u8 = kw_type(a, "u8");
        spl_type_id_t t = spl_type_ptr((spl_type_t *)&a->sema->type, u8);
        return const_str(a, fc, t, pn->primary_expr.string_lit_expr);
    }
    case SPL_AST_TRUE:
    case SPL_AST_FALSE:
        return const_bool(a, fc, pn->primary_expr.kind == SPL_AST_TRUE);
    case SPL_AST_NULL: {
        spl_type_id_t ht = underlying(a->sema, fc->hint);
        spl_type_node_t *htt = ht ? tn(a->sema, ht) : NULL;
        if (htt && htt->kind == SPL_TYPE_SLICE) {
            spl_ir_node_ref_t sl = emit_agg_construct(a, fc, ht);
            spl_type_id_t ep = spl_type_ptr((spl_type_t *)&a->sema->type, htt->slice_element);
            agg_construct_add(a, fc, sl, const_int(a, fc, ep, 0));
            agg_construct_add(a, fc, sl, const_int(a, fc, kw_type(a, "usize"), 0));
            return sl;
        }
        spl_type_id_t t = htt && htt->kind == SPL_TYPE_PTR
                              ? ht
                              : spl_type_ptr((spl_type_t *)&a->sema->type, kw_type(a, "void"));
        return const_int(a, fc, t, 0);
    }
    case SPL_AST_IDENT:
        return lower_ident(a, fc, pn->primary_expr.ident, pn->resolved_def_id, 0);
    case SPL_AST_EXPR_EXPR:
        return lower_expr(a, fc, pn->primary_expr.expr);
    case SPL_AST_BLOCK_EXPR:
        return lower_block_expr(a, fc, &pn->primary_expr.block_expr);
    case SPL_AST_ARRAY_LIT: {
        spl_type_id_t elem = resolve_type_expr(a, fc, pn->primary_expr.array_lit_expr.type_expr);
        if (!elem)
            elem = kw_type(a, "i32");
        spl_type_id_t arr = spl_type_array((spl_type_t *)&a->sema->type, elem,
                                           (usize)pn->primary_expr.array_lit_expr.integer);
        VEC(spl_ir_node_ref_t) vals;
        vec_init(vals);
        for (usize i = 0; i < pn->primary_expr.array_lit_expr.expr_list.size; i++) {
            fc->hint = elem;
            spl_ir_node_ref_t v =
                lower_expr(a, fc, pn->primary_expr.array_lit_expr.expr_list.data[i]);
            fc->hint = 0;
            v = coerce_to(a, fc, v, node_type(fc, v), elem);
            vec_push(vals, v);
        }
        spl_ir_node_ref_t agg = emit_agg_construct(a, fc, arr);
        for (usize i = 0; i < vals.size; i++)
            agg_construct_add(a, fc, agg, vals.data[i]);
        vec_free(vals);
        return agg;
    }
    case SPL_AST_ARGGREGATE_INIT: {
        spl_type_id_t tid = 0;
        if (pn->primary_expr.aggregate_init.name) {
            spl_def_id_t def = root_lookup(a, pn->primary_expr.aggregate_init.name);
            if (def)
                tid = underlying(a->sema, def_at(a->sema, def)->type_id);
            else {
                ir_env_t *it = env_find(fc, pn->primary_expr.aggregate_init.name);
                if (it && it->is_type)
                    tid = underlying(a->sema, it->tid);
            }
        } else {
            spl_type_id_t hint_t = underlying(a->sema, fc->hint);
            spl_type_node_t *htt = hint_t ? tn(a->sema, hint_t) : NULL;
            if (!htt || (htt->kind != SPL_TYPE_STRUCT && htt->kind != SPL_TYPE_UNION &&
                         htt->kind != SPL_TYPE_SLICE && htt->kind != SPL_TYPE_RANGE)) {
                diag(a, fc, 0, "anonymous aggregate literal without context type");
                return 0;
            }
            VEC(spl_ir_node_ref_t) vals;
            vec_init(vals);
            for (usize j = 0; j < pn->primary_expr.aggregate_init.expr.size; j++) {
                spl_ast_node_t *item =
                    node_at(a->sema, pn->primary_expr.aggregate_init.expr.data[j]);
                if (!item || !item->aggregate_init_item.ident)
                    continue;
                isize fidx = agg_index_or_builtin(a, hint_t, item->aggregate_init_item.ident);
                if (fidx < 0) {
                    diag(a, fc, 0, "unknown field in aggregate literal");
                    continue;
                }
                spl_type_id_t ft = agg_field_tid_or_builtin(a, hint_t, fidx);
                spl_ir_node_ref_t v = lower_expr(a, fc, item->aggregate_init_item.expr);
                /* 字段是指针、值是聚合 lvalue：自动取地址<E59CB0>?left = expr 语义<E8AFAD>?*/
                spl_type_node_t *fld_t = ft ? tn(a->sema, ft) : NULL;
                spl_type_node_t *v_t = tn(a->sema, underlying(a->sema, node_type(fc, v)));
                if (fld_t && fld_t->kind == SPL_TYPE_PTR && v_t &&
                    (v_t->kind == SPL_TYPE_STRUCT || v_t->kind == SPL_TYPE_UNION ||
                     v_t->kind == SPL_TYPE_ENUM)) {
                    spl_type_id_t lt = 0;
                    spl_ir_node_ref_t addr =
                        lower_lvalue(a, fc, item->aggregate_init_item.expr, &lt);
                    if (addr)
                        v = addr;
                }
                if (ft)
                    v = coerce_to(a, fc, v, node_type(fc, v), ft);
                vec_push(vals, v);
            }
            spl_ir_node_ref_t agg = emit_agg_construct(a, fc, hint_t);
            for (usize i = 0; i < vals.size; i++)
                agg_construct_add(a, fc, agg, vals.data[i]);
            vec_free(vals);
            return agg;
        }
        spl_type_node_t *tt = tn(a->sema, tid);
        if (!tt)
            return 0;
        if (tt->kind == SPL_TYPE_ENUM) {
            VEC(spl_ir_node_ref_t) vals;
            vec_init(vals);
            for (usize j = 0; j < pn->primary_expr.aggregate_init.expr.size; j++) {
                spl_ast_node_t *item =
                    node_at(a->sema, pn->primary_expr.aggregate_init.expr.data[j]);
                if (!item || !item->aggregate_init_item.ident)
                    continue;
                isize vidx = enum_variant_index(a, tid, item->aggregate_init_item.ident);
                if (vidx < 0) {
                    diag(a, fc, 0, "unknown enum variant");
                    continue;
                }
                vec_push(vals, const_int(a, fc, enum_tag_tid(a), (usize)vidx));
                if (item->aggregate_init_item.expr) {
                    spl_type_id_t pt = enum_payload_tid(a, tid, vidx);
                    fc->hint = pt;
                    spl_ir_node_ref_t pv = lower_expr(a, fc, item->aggregate_init_item.expr);
                    fc->hint = 0;
                    if (pt)
                        pv = coerce_to(a, fc, pv, node_type(fc, pv), pt);
                    vec_push(vals, pv);
                }
            }
            spl_ir_node_ref_t agg = emit_agg_construct(a, fc, tid);
            for (usize i = 0; i < vals.size; i++)
                agg_construct_add(a, fc, agg, vals.data[i]);
            vec_free(vals);
            return agg;
        }
        if (tt->kind != SPL_TYPE_STRUCT) {
            diag(a, fc, 0, "aggregate literal target is not a struct");
            return 0;
        }
        spl_ir_node_ref_t agg = 0;
        usize nfields = tt->agg_field_types.size;
        VEC(spl_ir_node_ref_t) vals;
        vec_init(vals);
        for (usize i = 0; i < nfields; i++) {
            const char *fname = agg_field_name_at(a, tid, (isize)i);
            spl_ast_node_ref_t found = 0;
            for (usize j = 0; j < pn->primary_expr.aggregate_init.expr.size; j++) {
                spl_ast_node_t *item =
                    node_at(a->sema, pn->primary_expr.aggregate_init.expr.data[j]);
                if (item && fname && item->aggregate_init_item.ident &&
                    strcmp(item->aggregate_init_item.ident, fname) == 0) {
                    found = pn->primary_expr.aggregate_init.expr.data[j];
                    break;
                }
            }
            if (!found) {
                vec_push(vals, const_int(a, fc, tt->agg_field_types.data[i], 0));
                continue;
            }
            spl_ast_node_t *item = node_at(a->sema, found);
            fc->hint = tt->agg_field_types.data[i];
            spl_ir_node_ref_t v = lower_expr(a, fc, item->aggregate_init_item.expr);
            fc->hint = 0;
            /* 字段是指针、值是聚合 lvalue：自动取地址<E59CB0>?left = expr 语义<E8AFAD>?*/
            spl_type_node_t *fld_t = tn(a->sema, tt->agg_field_types.data[i]);
            spl_type_node_t *v_t = tn(a->sema, underlying(a->sema, node_type(fc, v)));
            if (fld_t && fld_t->kind == SPL_TYPE_PTR && v_t &&
                (v_t->kind == SPL_TYPE_STRUCT || v_t->kind == SPL_TYPE_UNION ||
                 v_t->kind == SPL_TYPE_ENUM)) {
                spl_type_id_t lt = 0;
                spl_ir_node_ref_t addr = lower_lvalue(a, fc, item->aggregate_init_item.expr, &lt);
                if (addr)
                    v = addr;
            }
            v = coerce_to(a, fc, v, node_type(fc, v), tt->agg_field_types.data[i]);
            vec_push(vals, v);
        }
        agg = emit_agg_construct(a, fc, tid);
        for (usize i = 0; i < vals.size; i++)
            agg_construct_add(a, fc, agg, vals.data[i]);
        vec_free(vals);
        return agg;
    }
    case SPL_AST_BUILTIN_EXPR: {
        const char *id = pn->primary_expr.builtin_expr.ident;
        if (strcmp(id, "sizeof") == 0 && pn->primary_expr.builtin_expr.expr_list.size) {
            spl_type_id_t t =
                type_from_type_like(a, fc, pn->primary_expr.builtin_expr.expr_list.data[0]);
            if (!t) {
                diag(a, fc, 0, "sizeof: cannot resolve type");
                return 0;
            }
            spl_ir_node_ref_t n = emit_node(a, fc);
            spl_ir_node_t *e = enode(a, fc, n);
            e->kind = SPL_IR_TYPE_SIZEOF;
            e->ir_sizeof.tid = t;
            set_ntype(fc, n, kw_type(a, "usize"));
            return n;
        }
        if (strcmp(id, "dbg") == 0) {
            for (usize i = 0; i < pn->primary_expr.builtin_expr.expr_list.size; i++)
                lower_expr(a, fc, pn->primary_expr.builtin_expr.expr_list.data[i]);
            spl_ir_node_ref_t n = emit_node(a, fc);
            spl_ir_node_t *e = enode(a, fc, n);
            e->kind = SPL_IR_DBG_BREAKPOINT;
            set_ntype(fc, n, kw_type(a, "void"));
            return n;
        }
        diag(a, fc, 0, "unsupported builtin call");
        return 0;
    }
    default:
        return 0;
    }
}

static spl_ir_node_ref_t lower_prefix(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_t *pf) {
    switch (pf->prefix_expr.kind) {
    case SPL_AST_MINUS_EXPR: {
        spl_ir_node_ref_t v = lower_expr(a, fc, pf->prefix_expr.postfix_expr);
        spl_type_id_t t = underlying(a->sema, node_type(fc, v));
        if (!is_num_type(a->sema, t)) {
            diag(a, fc, 0, "unary minus requires numeric");
            return 0;
        }
        return emit_arith(a, fc, SPL_IR_ARITH_NEG, t, v, 0);
    }
    case SPL_AST_BANG_EXPR: {
        spl_ir_node_ref_t v = lower_expr(a, fc, pf->prefix_expr.postfix_expr);
        spl_ir_node_ref_t z = const_bool(a, fc, 0);
        return emit_cmp(a, fc, SPL_IR_CMP_EQ, kw_type(a, "bool"), v, z);
    }
    case SPL_AST_TILDE_EXPR: {
        spl_ir_node_ref_t v = lower_expr(a, fc, pf->prefix_expr.postfix_expr);
        spl_type_id_t t = underlying(a->sema, node_type(fc, v));
        if (!is_int_type(a->sema, t)) {
            diag(a, fc, 0, "~ requires integer");
            return 0;
        }
        return emit_arith(a, fc, SPL_IR_ARITH_NOT, t, v, 0);
    }
    case SPL_AST_AMPERSAND_EXPR: {
        spl_type_id_t t = 0;
        spl_ir_node_ref_t addr = lower_lvalue(a, fc, pf->prefix_expr.postfix_expr, &t);
        if (addr) {
            spl_type_id_t pt = spl_type_ptr((spl_type_t *)&a->sema->type, t);
            set_ntype(fc, addr, pt);
            return addr;
        }
        spl_ast_node_t *operand = node_at(a->sema, pf->prefix_expr.postfix_expr);
        if (operand && operand->kind == SPL_AST_EXPR && operand->expr.op == SPL_AST_PRIMARY_EXPR) {
            spl_ast_node_t *pn = node_at(a->sema, operand->expr.op_expr.left);
            if (pn && pn->primary_expr.kind == SPL_AST_IDENT) {
                spl_def_id_t def = root_lookup(a, pn->primary_expr.ident);
                if (def) {
                    spl_def_node_t *d = def_at(a->sema, def);
                    if (d && d->kind == SPL_DEF_FN_PARAMS && d->type_id) {
                        spl_ir_func_ref_t fid = a2ir_fn_of(a, d->type_id);
                        if (fid)
                            return const_fnref(a, fc, d->type_id, fid);
                    }
                }
            }
        }
        diag(a, fc, 0, "& requires addressable operand");
        return 0;
    }
    case SPL_AST_ASTERISK_EXPR: {
        spl_ir_node_ref_t v = lower_expr(a, fc, pf->prefix_expr.postfix_expr);
        spl_type_id_t t = underlying(a->sema, node_type(fc, v));
        spl_type_node_t *tt = tn(a->sema, t);
        if (tt && tt->kind == SPL_TYPE_PTR) {
            spl_type_id_t pointee = underlying(a->sema, tt->ptr_pointee);
            return emit_load(a, fc, pointee, v);
        }
        return v;
    }
    default:
        return 0;
    }
}

/* ---- 调用目标 ---- */

typedef struct {
    spl_type_id_t fn_tid;
    spl_ir_node_ref_t callee;
} callee_t;

static int resolve_callee(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_t base, callee_t *out) {
    memset(out, 0, sizeof *out);
    spl_ast_node_t *n = node_at(a->sema, base);
    if (!n || n->kind != SPL_AST_EXPR)
        return 0;
    if (n->expr.op == SPL_AST_PRIMARY_EXPR) {
        spl_ast_node_t *pn = node_at(a->sema, n->expr.op_expr.left);
        if (pn && pn->primary_expr.kind == SPL_AST_IDENT) {
            const char *name = pn->primary_expr.ident;
            ir_env_t *it = env_find_def(fc, pn->resolved_def_id, name);
            if (it && it->is_type) {
                diag(a, fc, base, "type is not callable");
                return 0;
            }
            spl_def_id_t def = root_lookup(a, name);
            if (def) {
                spl_def_node_t *d = def_at(a->sema, def);
                if (d && d->kind == SPL_DEF_FN_PARAMS && d->type_id) {
                    out->fn_tid = d->type_id;
                    spl_ir_func_ref_t fid = a2ir_fn_of(a, d->type_id);
                    if (fid) {
                        out->callee = const_fnref(a, fc, d->type_id, fid);
                        return 1;
                    }
                    diag(a, fc, base, "function has no IR function");
                    return 0;
                }
            }
            /* 命名空间内裸名互调：Str.from_cstr 中调cstrlen(...) */
            if (fc->ns_tid) {
                spl_type_id_t mt = agg_member_type(a, fc->ns_tid, name);
                spl_type_node_t *mtn = mt ? tn(a->sema, mt) : NULL;
                if (mt && mtn && mtn->kind == SPL_TYPE_FN) {
                    out->fn_tid = mt;
                    spl_ir_func_ref_t fid = a2ir_fn_of(a, mt);
                    if (fid) {
                        out->callee = const_fnref(a, fc, mt, fid);
                        return 1;
                    }
                }
            }
        }
    }
    if (n->expr.op == SPL_AST_POSTFIX_EXPR) {
        spl_ast_node_t *pf = node_at(a->sema, n->expr.op_expr.left);
        if (pf && pf->postfix_expr.kind == SPL_AST_FIELD_EXPR) {
            const char *fname = pf->postfix_expr.field_expr;
            spl_ast_node_ref_t bref = pf->postfix_expr.primary_expr;
            spl_type_id_t ttr = type_of_type_ref(a, fc, bref);
            if (ttr) {
                spl_type_id_t mt = agg_member_type(a, ttr, fname);
                spl_type_node_t *mtn = tn(a->sema, mt);
                if (mt && mtn && mtn->kind == SPL_TYPE_FN) {
                    out->fn_tid = mt;
                    spl_ir_func_ref_t fid = a2ir_fn_of(a, mt);
                    if (fid) {
                        out->callee = const_fnref(a, fc, mt, fid);
                        return 1;
                    }
                }
            }
            spl_ir_node_ref_t bv = lower_expr(a, fc, bref);
            spl_type_id_t vt = underlying(a->sema, node_type(fc, bv));
            spl_type_node_t *vtt = vt ? tn(a->sema, vt) : NULL;
            if (vtt && vtt->kind == SPL_TYPE_PTR) {
                vt = underlying(a->sema, vtt->ptr_pointee);
                vtt = tn(a->sema, vt);
            }
            /* enum 方法：在原 enum def 上查找 */
            spl_type_id_t lookup = vt;
            spl_type_id_t e0 = 0;
            if (vtt && is_enum_expand(a, vt, &e0))
                lookup = e0;
            spl_type_id_t mt = vtt ? agg_member_type(a, lookup, fname) : 0;
            spl_type_node_t *mtn = mt ? tn(a->sema, mt) : NULL;
            if (mt && mtn && mtn->kind == SPL_TYPE_FN) {
                out->fn_tid = mt;
                spl_ir_func_ref_t fid = a2ir_fn_of(a, mt);
                if (fid) {
                    out->callee = const_fnref(a, fc, mt, fid);
                    return 1;
                }
            }
        }
    }
    out->callee = lower_expr(a, fc, base);
    out->fn_tid = node_type(fc, out->callee);
    if (out->fn_tid) {
        spl_type_node_t *ft = tn(a->sema, underlying(a->sema, out->fn_tid));
        if (ft && ft->kind != SPL_TYPE_FN) {
            diag(a, fc, base, "call requires function type");
            return 0;
        }
        return 1;
    }
    return 0;
}

static spl_ir_node_ref_t lower_field(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_t *pf) {
    const char *fname = pf->postfix_expr.field_expr;
    spl_type_id_t ttr = type_of_type_ref(a, fc, pf->postfix_expr.primary_expr);
    if (ttr) {
        spl_type_node_t *ttr_t = tn(a->sema, ttr);
        if (ttr_t && ttr_t->kind == SPL_TYPE_ENUM) {
            isize vidx = enum_variant_index(a, ttr, fname);
            if (vidx >= 0)
                return enum_variant_value(a, fc, ttr, vidx);
        }
        /* 聚合命名空间成员：static var/const <20>?全局数据 */
        spl_def_id_t gdef = def_for_type(a, ttr);
        spl_def_node_t *gd = gdef ? def_at(a->sema, gdef) : NULL;
        for (usize i = 0; gd && i < gd->agg_def.size; i++) {
            spl_var_def_t *e = &gd->agg_def.data[i];
            if (e->name && strcmp(e->name, fname) == 0 && e->def_id) {
                spl_def_node_t *ed = def_at(a->sema, e->def_id);
                if (ed && ed->kind == SPL_DEF_VAR) {
                    isize gi = gdata_index_by_def(a, e->def_id);
                    if (gi >= 0)
                        return emit_load(a, fc, e->type_id,
                                         emit_global_alloc(a, fc, e->type_id, (usize)gi));
                }
                break;
            }
        }
        diag(a, fc, 0, "aggregate member is not a value");
        return 0;
    }
    spl_ir_node_ref_t base = lower_expr(a, fc, pf->postfix_expr.primary_expr);
    if (!base)
        return 0;
    spl_type_id_t bt = underlying(a->sema, node_type(fc, base));
    spl_type_node_t *tt = tn(a->sema, bt);
    if (!tt)
        return 0;
    spl_type_id_t agg_tid = bt;
    spl_ir_node_ref_t agg_val = base;
    if (tt->kind == SPL_TYPE_PTR) {
        agg_tid = underlying(a->sema, tt->ptr_pointee);
        tt = tn(a->sema, agg_tid);
        agg_val = emit_load(a, fc, agg_tid, base);
    }
    if (!tt)
        return 0;
    if (tt->kind == SPL_TYPE_SLICE) {
        if (strcmp(fname, "ptr") == 0) {
            spl_type_id_t ft = spl_type_ptr((spl_type_t *)&a->sema->type, tt->slice_element);
            return emit_agg_extract(a, fc, agg_tid, ft, 0, agg_val);
        }
        if (strcmp(fname, "len") == 0)
            return emit_agg_extract(a, fc, agg_tid, kw_type(a, "usize"), 1, agg_val);
        diag(a, fc, 0, "unknown slice field");
        return 0;
    }
    if (tt->kind == SPL_TYPE_RANGE) {
        if (strcmp(fname, "begin") == 0)
            return emit_agg_extract(a, fc, agg_tid, tt->range_element, 0, agg_val);
        if (strcmp(fname, "end") == 0)
            return emit_agg_extract(a, fc, agg_tid, tt->range_element, 1, agg_val);
        diag(a, fc, 0, "unknown range field");
        return 0;
    }
    isize fidx = agg_member_index(a, agg_tid, fname);
    if (fidx < 0) {
        diag(a, fc, 0, "unknown field");
        return 0;
    }
    spl_type_id_t ft = agg_field_tid_at(a, agg_tid, fidx);
    return emit_agg_extract(a, fc, agg_tid, ft, fidx, agg_val);
}

static spl_ir_node_ref_t lower_postfix(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_t *pf) {
    switch (pf->postfix_expr.kind) {
    case SPL_AST_CALL_EXPR: {
        callee_t cal;
        if (!resolve_callee(a, fc, pf->postfix_expr.primary_expr, &cal))
            return 0;
        spl_type_node_t *ft = tn(a->sema, underlying(a->sema, cal.fn_tid));
        usize nparams = (ft && ft->kind == SPL_TYPE_FN) ? ft->fn_type.params.size : 0;
        spl_ast_node_ref_vec_t *args = &pf->postfix_expr.call_expr;
        spl_ir_node_ref_t av[64];
        usize na = args->size < 64 ? args->size : 64;
        for (usize i = 0; i < na; i++) {
            spl_type_id_t pt = 0;
            if (i < nparams && ft && ft->kind == SPL_TYPE_FN)
                pt = ft->fn_type.params.data[i];
            fc->hint = pt;
            spl_ir_node_ref_t v = lower_expr(a, fc, args->data[i]);
            fc->hint = 0;
            if (pt)
                v = coerce_to(a, fc, v, node_type(fc, v), pt);
            av[i] = v;
        }
        return emit_call(a, fc, cal.fn_tid, cal.callee, av, na);
    }
    case SPL_AST_FIELD_EXPR:
        return lower_field(a, fc, pf);
    case SPL_AST_DEREF_EXPR: {
        spl_ir_node_ref_t p = lower_expr(a, fc, pf->postfix_expr.primary_expr);
        spl_type_id_t pt = underlying(a->sema, node_type(fc, p));
        spl_type_node_t *tt = tn(a->sema, pt);
        if (!tt || tt->kind != SPL_TYPE_PTR) {
            diag(a, fc, 0, ".* requires pointer");
            return 0;
        }
        spl_type_id_t pointee = underlying(a->sema, tt->ptr_pointee);
        return emit_load(a, fc, pointee, p);
    }
    case SPL_AST_INDEX_EXPR: {
        spl_type_id_t elem = 0;
        spl_ir_node_ref_t addr = index_addr(a, fc, pf, &elem);
        if (!addr)
            return 0;
        return emit_load(a, fc, elem, addr);
    }
    case SPL_AST_SLICE_EXPR: {
        spl_type_id_t bt = 0;
        spl_ir_node_ref_t base_lv = lower_lvalue(a, fc, pf->postfix_expr.primary_expr, &bt);
        spl_type_node_t *tt = tn(a->sema, underlying(a->sema, bt));
        if (!tt || (tt->kind != SPL_TYPE_ARRAY && tt->kind != SPL_TYPE_SLICE)) {
            diag(a, fc, 0, "slice requires array/slice");
            return 0;
        }
        spl_type_id_t elem =
            tt->kind == SPL_TYPE_ARRAY ? tt->array_type.element : tt->slice_element;
        spl_type_id_t slice_t = spl_type_slice((spl_type_t *)&a->sema->type, elem);
        spl_ir_node_ref_t base_ptr = 0;
        spl_ir_node_ref_t total_len = 0;
        if (tt->kind == SPL_TYPE_ARRAY) {
            base_ptr = base_lv;
            total_len = const_int(a, fc, kw_type(a, "usize"), tt->array_type.len);
        } else {
            spl_ir_node_ref_t slv = emit_load(a, fc, bt, base_lv);
            spl_type_id_t ep = spl_type_ptr((spl_type_t *)&a->sema->type, elem);
            base_ptr = emit_agg_extract(a, fc, bt, ep, 0, slv);
            total_len = emit_agg_extract(a, fc, bt, kw_type(a, "usize"), 1, slv);
        }
        spl_ir_node_ref_t beg = 0, end = 0;
        if (pf->postfix_expr.slice_expr.begin)
            beg = lower_expr(a, fc, pf->postfix_expr.slice_expr.begin);
        else
            beg = const_int(a, fc, kw_type(a, "usize"), 0);
        if (pf->postfix_expr.slice_expr.end)
            end = lower_expr(a, fc, pf->postfix_expr.slice_expr.end);
        spl_type_id_t iszt = kw_type(a, "isize");
        spl_ir_node_ref_t ptr =
            emit_offset(a, fc, elem, base_ptr, coerce_to(a, fc, beg, node_type(fc, beg), iszt));
        spl_ir_node_ref_t len = 0;
        spl_ir_node_ref_t begu = coerce_to(a, fc, beg, node_type(fc, beg), kw_type(a, "usize"));
        if (end) {
            len = emit_arith(a, fc, SPL_IR_ARITH_SUB, kw_type(a, "usize"),
                             coerce_to(a, fc, end, node_type(fc, end), kw_type(a, "usize")), begu);
        } else {
            len = emit_arith(a, fc, SPL_IR_ARITH_SUB, kw_type(a, "usize"), total_len, begu);
        }
        spl_ir_node_ref_t sl = emit_agg_construct(a, fc, slice_t);
        agg_construct_add(a, fc, sl, ptr);
        agg_construct_add(a, fc, sl, len);
        return sl;
    }
    case SPL_AST_AS_EXPR: {
        spl_ir_node_ref_t v = lower_expr(a, fc, pf->postfix_expr.primary_expr);
        spl_type_id_t dt = resolve_type_expr(a, fc, pf->postfix_expr.type_expr);
        if (!dt)
            return v;
        return coerce_to(a, fc, v, node_type(fc, v), dt);
    }
    default:
        return 0;
    }
}

static spl_ir_node_ref_t lower_binary(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_t *n) {
    spl_ast_node_ref_t lr = n->expr.op_expr.left;
    spl_ast_node_ref_t rr = n->expr.op_expr.right;
    switch (n->expr.op) {
    case SPL_AST_ADD_EXPR:
    case SPL_AST_SUB_EXPR:
    case SPL_AST_MUL_EXPR:
    case SPL_AST_DIV_EXPR:
    case SPL_AST_MOD_EXPR:
    case SPL_AST_BITOR_EXPR:
    case SPL_AST_BITXOR_EXPR:
    case SPL_AST_BITAND_EXPR:
    case SPL_AST_LSHIFT_EXPR:
    case SPL_AST_RSHIFT_EXPR: {
        spl_ir_node_ref_t l = lower_expr(a, fc, lr);
        spl_ir_node_ref_t r = lower_expr(a, fc, rr);
        spl_type_id_t lt = underlying(a->sema, node_type(fc, l));
        spl_type_id_t rt = underlying(a->sema, node_type(fc, r));
        if ((n->expr.op == SPL_AST_ADD_EXPR || n->expr.op == SPL_AST_SUB_EXPR) &&
            is_ptr_type(a->sema, lt) && is_int_type(a->sema, rt)) {
            spl_type_node_t *ltt = tn(a->sema, lt);
            spl_type_id_t elem = underlying(a->sema, ltt->ptr_pointee);
            spl_ir_node_ref_t off = coerce_to(a, fc, r, rt, kw_type(a, "isize"));
            if (n->expr.op == SPL_AST_SUB_EXPR) {
                spl_ir_node_ref_t zero = const_int(a, fc, kw_type(a, "isize"), 0);
                off = emit_arith(a, fc, SPL_IR_ARITH_SUB, kw_type(a, "isize"), zero, off);
            }
            return emit_offset(a, fc, elem, l, off);
        }
        spl_type_id_t res = lt;
        if (!type_same(a->sema, lt, rt)) {
            if (expr_is_int_literal(a, lr) && is_int_type(a->sema, rt))
                res = rt;
            else if (expr_is_int_literal(a, rr) && is_int_type(a->sema, lt))
                res = lt;
            else
                res = lt;
        }
        spl_ir_kind_t k;
        switch (n->expr.op) {
        case SPL_AST_ADD_EXPR:
            k = SPL_IR_ARITH_ADD;
            break;
        case SPL_AST_SUB_EXPR:
            k = SPL_IR_ARITH_SUB;
            break;
        case SPL_AST_MUL_EXPR:
            k = SPL_IR_ARITH_MUL;
            break;
        case SPL_AST_DIV_EXPR:
            k = SPL_IR_ARITH_DIV;
            break;
        case SPL_AST_MOD_EXPR:
            k = SPL_IR_ARITH_REM;
            break;
        case SPL_AST_BITOR_EXPR:
            k = SPL_IR_ARITH_OR;
            break;
        case SPL_AST_BITXOR_EXPR:
            k = SPL_IR_ARITH_XOR;
            break;
        case SPL_AST_BITAND_EXPR:
            k = SPL_IR_ARITH_AND;
            break;
        case SPL_AST_LSHIFT_EXPR:
            k = SPL_IR_ARITH_SHL;
            break;
        default:
            k = SPL_IR_ARITH_SHR;
            break;
        }
        spl_ir_node_ref_t l2 = coerce_to(a, fc, l, lt, res);
        spl_ir_node_ref_t r2 = coerce_to(a, fc, r, rt, res);
        return emit_arith(a, fc, k, res, l2, r2);
    }
    case SPL_AST_CMPEQ_EXPR:
    case SPL_AST_CMPNE_EXPR:
    case SPL_AST_CMP_LE_EXPR:
    case SPL_AST_CMP_GE_EXPR:
    case SPL_AST_CMP_LT_EXPR:
    case SPL_AST_CMP_GT_EXPR: {
        spl_ir_node_ref_t l = lower_expr(a, fc, lr);
        spl_ir_node_ref_t r = lower_expr(a, fc, rr);
        spl_type_id_t lt = underlying(a->sema, node_type(fc, l));
        spl_type_id_t rt = underlying(a->sema, node_type(fc, r));
        spl_type_id_t le = 0, re = 0;
        int is_l_enum = is_enum_expand(a, lt, &le);
        int is_r_enum = is_enum_expand(a, rt, &re);
        if (is_l_enum && is_r_enum) {
            spl_type_id_t tag_t = enum_tag_tid(a);
            l = enum_tag_of(a, fc, le, l);
            r = enum_tag_of(a, fc, re, r);
            lt = tag_t;
            rt = tag_t;
        }
        spl_type_id_t res = lt;
        if (!type_same(a->sema, lt, rt)) {
            if (is_int_type(a->sema, lt) && is_int_type(a->sema, rt))
                res = expr_is_int_literal(a, lr) ? rt : lt;
            else
                res = lt;
        }
        l = coerce_to(a, fc, l, node_type(fc, l), res);
        r = coerce_to(a, fc, r, node_type(fc, r), res);
        spl_ir_kind_t k;
        switch (n->expr.op) {
        case SPL_AST_CMPEQ_EXPR:
            k = SPL_IR_CMP_EQ;
            break;
        case SPL_AST_CMPNE_EXPR:
            k = SPL_IR_CMP_NE;
            break;
        case SPL_AST_CMP_LE_EXPR:
            k = SPL_IR_CMP_LE;
            break;
        case SPL_AST_CMP_GE_EXPR:
            k = SPL_IR_CMP_GE;
            break;
        case SPL_AST_CMP_LT_EXPR:
            k = SPL_IR_CMP_LT;
            break;
        default:
            k = SPL_IR_CMP_GT;
            break;
        }
        return emit_cmp(a, fc, k, res, l, r);
    }
    case SPL_AST_BOOLAND_EXPR:
    case SPL_AST_BOOLOR_EXPR: {
        spl_type_id_t bt = kw_type(a, "bool");
        spl_ir_node_ref_t l = lower_expr(a, fc, lr);
        usize t = new_block(fc), f = new_block(fc), join = new_block(fc);
        spl_ir_node_ref_t slot = emit_alloca(a, fc, bt);
        emit_br(a, fc, l, t, f);
        begin_block(fc, t);
        if (n->expr.op == SPL_AST_BOOLAND_EXPR) {
            spl_ir_node_ref_t r = lower_expr(a, fc, rr);
            emit_store(a, fc, bt, slot, r);
        } else {
            emit_store(a, fc, bt, slot, const_bool(a, fc, 1));
        }
        emit_jmp(a, fc, join);
        begin_block(fc, f);
        if (n->expr.op == SPL_AST_BOOLAND_EXPR) {
            emit_store(a, fc, bt, slot, const_bool(a, fc, 0));
        } else {
            spl_ir_node_ref_t r = lower_expr(a, fc, rr);
            emit_store(a, fc, bt, slot, r);
        }
        emit_jmp(a, fc, join);
        begin_block(fc, join);
        return emit_load(a, fc, bt, slot);
    }
    default:
        return 0;
    }
}

static spl_ir_node_ref_t lower_range_value(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_t *n) {
    spl_ir_node_ref_t b = lower_expr(a, fc, n->expr.op_expr.left);
    spl_type_id_t et = underlying(a->sema, node_type(fc, b));
    spl_type_id_t range_t = spl_type_range((spl_type_t *)&a->sema->type, et);
    spl_ir_node_ref_t e =
        n->expr.op_expr.right ? lower_expr(a, fc, n->expr.op_expr.right) : const_int(a, fc, et, 0);
    spl_ir_node_ref_t r = emit_agg_construct(a, fc, range_t);
    agg_construct_add(a, fc, r, b);
    agg_construct_add(a, fc, r, e);
    return r;
}

static spl_ir_node_ref_t lower_compound_op(spl_ast2ir_t *a, fnctx_t *fc, int op, spl_type_id_t tid,
                                           spl_ir_node_ref_t cur, spl_ir_node_ref_t rhs) {
    spl_ir_kind_t k;
    switch (op) {
    case SPL_AST_ASSIGN_ADD_EXPR:
        k = SPL_IR_ARITH_ADD;
        break;
    case SPL_AST_ASSIGN_sUB_EXPR:
        k = SPL_IR_ARITH_SUB;
        break;
    case SPL_AST_ASSIGN_MUL_EXPR:
        k = SPL_IR_ARITH_MUL;
        break;
    case SPL_AST_ASSIGN_DIV_EXPR:
        k = SPL_IR_ARITH_DIV;
        break;
    case SPL_AST_ASSIGN_MOD_EXPR:
        k = SPL_IR_ARITH_REM;
        break;
    case SPL_AST_ASSIGN_AND_EXPR:
        k = SPL_IR_ARITH_AND;
        break;
    case SPL_AST_ASSIGN_OR_EXPR:
        k = SPL_IR_ARITH_OR;
        break;
    case SPL_AST_ASSIGN_XOR_EXPR:
        k = SPL_IR_ARITH_XOR;
        break;
    case SPL_AST_ASSIGN_LSHIFT_EXPR:
        k = SPL_IR_ARITH_SHL;
        break;
    case SPL_AST_ASSIGN_USHIFT_EXPR:
        k = SPL_IR_ARITH_SHR;
        break;
    default:
        return rhs;
    }
    spl_ir_node_ref_t r = coerce_to(a, fc, rhs, node_type(fc, rhs), tid);
    return emit_arith(a, fc, k, tid, cur, r);
}

/* 字段链赋o.a.b = rhs：直接按字节地址写回（含指针中间字段*/
static void field_assign(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_t target,
                         spl_ir_node_ref_t rhs) {
    spl_type_id_t ft = 0;
    spl_ir_node_ref_t addr = lower_field_address(a, fc, target, &ft);
    if (!addr || !ft) {
        diag(a, fc, target, "field assignment: unsupported base");
        return;
    }
    rhs = coerce_to(a, fc, rhs, node_type(fc, rhs), ft);
    emit_store(a, fc, ft, addr, rhs);
}

static spl_ir_node_ref_t lower_assign(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_t *n) {
    spl_ast_node_ref_t lr = n->expr.op_expr.left;
    spl_ast_node_ref_t rr = n->expr.op_expr.right;
    spl_ast_node_t *ln = node_at(a->sema, lr);
    if (!ln || ln->kind != SPL_AST_EXPR)
        return 0;
    int compound = n->expr.op != SPL_AST_ASSIGN_EXPR;
    spl_ast_node_t *pf = NULL;
    if (ln->expr.op == SPL_AST_POSTFIX_EXPR)
        pf = node_at(a->sema, ln->expr.op_expr.left);

    if (ln->expr.op == SPL_AST_PRIMARY_EXPR) {
        spl_ast_node_t *pn = node_at(a->sema, ln->expr.op_expr.left);
        if (pn && pn->primary_expr.kind == SPL_AST_IDENT) {
            ir_env_t *it = env_find_def(fc, pn->resolved_def_id, pn->primary_expr.ident);
            spl_type_id_t lt = 0;
            spl_ir_node_ref_t target = 0;
            if (it && it->slot) {
                lt = it->tid;
                target = it->slot;
            } else {
                /* 全局 var（顶<EFBC88>?/ 命名空间裸名<E8A3B8>?*/
                spl_def_id_t def = pn->resolved_def_id;
                if (!def)
                    def = root_lookup(a, pn->primary_expr.ident);
                if (def) {
                    spl_def_node_t *d = def_at(a->sema, def);
                    isize gi0 = (d && d->kind == SPL_DEF_VAR) ? gdata_index_by_def(a, def) : -1;
                    if (gi0 >= 0) {
                        lt = d->type_id;
                        target = emit_global_alloc(a, fc, lt, (usize)gi0);
                    } else if (fc->ns_tid) {
                        spl_def_id_t gdef = def_for_type(a, fc->ns_tid);
                        spl_def_node_t *gd = gdef ? def_at(a->sema, gdef) : NULL;
                        for (usize i = 0; gd && i < gd->agg_def.size; i++) {
                            spl_var_def_t *e = &gd->agg_def.data[i];
                            if (e->name && strcmp(e->name, pn->primary_expr.ident) == 0 &&
                                e->def_id) {
                                spl_def_node_t *ed = def_at(a->sema, e->def_id);
                                if (ed && ed->kind == SPL_DEF_VAR) {
                                    isize gi = gdata_index_by_def(a, e->def_id);
                                    if (gi >= 0) {
                                        lt = e->type_id;
                                        target = emit_global_alloc(a, fc, e->type_id, (usize)gi);
                                    }
                                }
                                break;
                            }
                        }
                    }
                }
            }
            if (!target || !lt) {
                diag(a, fc, lr, "assignment target not writable");
                return 0;
            }
            spl_ir_node_ref_t cur = compound ? emit_load(a, fc, lt, target) : 0;
            spl_ir_node_ref_t v = lower_expr(a, fc, rr);
            if (compound)
                v = lower_compound_op(a, fc, n->expr.op, lt, cur, v);
            v = coerce_to(a, fc, v, node_type(fc, v), lt);
            emit_store(a, fc, lt, target, v);
            return v;
        }
    }
    if (ln->expr.op == SPL_AST_PREFIX_EXPR) {
        spl_ast_node_t *pp = node_at(a->sema, ln->expr.op_expr.left);
        if (pp && pp->prefix_expr.kind == SPL_AST_ASTERISK_EXPR) {
            spl_ir_node_ref_t p = lower_expr(a, fc, pp->prefix_expr.postfix_expr);
            spl_type_id_t pt = underlying(a->sema, node_type(fc, p));
            spl_type_node_t *tt = tn(a->sema, pt);
            if (tt && tt->kind == SPL_TYPE_PTR) {
                spl_type_id_t pointee = underlying(a->sema, tt->ptr_pointee);
                spl_ir_node_ref_t cur = compound ? emit_load(a, fc, pointee, p) : 0;
                spl_ir_node_ref_t v = lower_expr(a, fc, rr);
                if (compound)
                    v = lower_compound_op(a, fc, n->expr.op, pointee, cur, v);
                v = coerce_to(a, fc, v, node_type(fc, v), pointee);
                emit_store(a, fc, pointee, p, v);
                return v;
            }
        }
    }
    if (pf && pf->postfix_expr.kind == SPL_AST_DEREF_EXPR) {
        spl_ir_node_ref_t p = lower_expr(a, fc, pf->postfix_expr.primary_expr);
        spl_type_id_t pt = underlying(a->sema, node_type(fc, p));
        spl_type_node_t *tt = tn(a->sema, pt);
        if (!tt || tt->kind != SPL_TYPE_PTR) {
            diag(a, fc, lr, ".* requires pointer");
            return 0;
        }
        spl_type_id_t pointee = underlying(a->sema, tt->ptr_pointee);
        spl_ir_node_ref_t cur = compound ? emit_load(a, fc, pointee, p) : 0;
        spl_ir_node_ref_t v = lower_expr(a, fc, rr);
        if (compound)
            v = lower_compound_op(a, fc, n->expr.op, pointee, cur, v);
        v = coerce_to(a, fc, v, node_type(fc, v), pointee);
        emit_store(a, fc, pointee, p, v);
        return v;
    }
    if (pf && pf->postfix_expr.kind == SPL_AST_INDEX_EXPR) {
        spl_type_id_t elem = 0;
        spl_ir_node_ref_t addr = index_addr(a, fc, pf, &elem);
        if (!addr)
            return 0;
        spl_ir_node_ref_t cur = compound ? emit_load(a, fc, elem, addr) : 0;
        spl_ir_node_ref_t v = lower_expr(a, fc, rr);
        if (compound)
            v = lower_compound_op(a, fc, n->expr.op, elem, cur, v);
        v = coerce_to(a, fc, v, node_type(fc, v), elem);
        emit_store(a, fc, elem, addr, v);
        return v;
    }
    if (pf && pf->postfix_expr.kind == SPL_AST_FIELD_EXPR) {
        spl_ir_node_ref_t v = lower_expr(a, fc, rr);
        if (compound) {
            spl_ir_node_ref_t cur = lower_expr(a, fc, lr);
            v = lower_compound_op(a, fc, n->expr.op, node_type(fc, cur), cur, v);
        }
        field_assign(a, fc, lr, v);
        return v;
    }
    diag(a, fc, lr, "unsupported assignment target");
    return 0;
}

static spl_ir_node_ref_t lower_expr(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_t ref) {
    spl_ast_node_t *n = node_at(a->sema, ref);
    if (!n || n->kind != SPL_AST_EXPR)
        return 0;
    switch (n->expr.op) {
    case SPL_AST_PRIMARY_EXPR:
        return lower_primary(a, fc, node_at(a->sema, n->expr.op_expr.left));
    case SPL_AST_PREFIX_EXPR:
        return lower_prefix(a, fc, node_at(a->sema, n->expr.op_expr.left));
    case SPL_AST_POSTFIX_EXPR:
        return lower_postfix(a, fc, node_at(a->sema, n->expr.op_expr.left));
    case SPL_AST_RANGE_EXPR:
        return lower_range_value(a, fc, n);
    case SPL_AST_ASSIGN_EXPR:
    case SPL_AST_ASSIGN_ADD_EXPR:
    case SPL_AST_ASSIGN_sUB_EXPR:
    case SPL_AST_ASSIGN_MUL_EXPR:
    case SPL_AST_ASSIGN_DIV_EXPR:
    case SPL_AST_ASSIGN_MOD_EXPR:
    case SPL_AST_ASSIGN_AND_EXPR:
    case SPL_AST_ASSIGN_OR_EXPR:
    case SPL_AST_ASSIGN_XOR_EXPR:
    case SPL_AST_ASSIGN_LSHIFT_EXPR:
    case SPL_AST_ASSIGN_USHIFT_EXPR:
        return lower_assign(a, fc, n);
    default:
        return lower_binary(a, fc, n);
    }
}

/* ================================================================
 * 语句
 * ================================================================ */

static void lower_block(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_vec_t *block) {
    env_push(fc);
    for (usize i = 0; i < block->size; i++)
        lower_stmt(a, fc, block->data[i]);
    if (!fc->terminated)
        emit_scope_defers(a, fc, fc->env.size - 1);
    env_pop(fc);
}

/* 登记 defer 体到当前作用*/
static void lower_defer(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_t ref) {
    if (!fc->env.size)
        env_push(fc);
    vec_push(fc->env.data[fc->env.size - 1].defers, ref);
}

/* 逆序发射 scope_idx 作用域的 defer，并清空 */
static void emit_scope_defers(spl_ast2ir_t *a, fnctx_t *fc, usize scope_idx) {
    if (scope_idx >= fc->env.size)
        return;
    for (usize i = fc->env.data[scope_idx].defers.size; i > 0; i--) {
        spl_ast_node_t *d = node_at(a->sema, fc->env.data[scope_idx].defers.data[i - 1]);
        if (d) {
            lower_block(a, fc, &d->block_item.defer_statement.block_or_statement);
        }
    }
    vec_free(fc->env.data[scope_idx].defers);
    vec_init(fc->env.data[scope_idx].defers);
}

/* 从最内层作用域发射到 mark（含），用于 ret / break / continue */
static void emit_defers_from(spl_ast2ir_t *a, fnctx_t *fc, usize mark) {
    for (usize i = fc->env.size; i > mark; i--)
        emit_scope_defers(a, fc, i - 1);
}

static void lower_type_decl(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_t *td) {
    spl_type_id_t tid = resolve_type_expr(a, fc, td->type_decl.type_expr);
    env_add(fc, td->type_decl.name, td->resolved_def_id, tid, 0, 0, 1, 0);
}

static void lower_var_decl(spl_ast2ir_t *a, fnctx_t *fc, const char *name, spl_def_id_t def_id,
                           spl_ast_node_ref_t texpr, spl_ast_node_ref_t initexpr) {
    spl_type_id_t tid = texpr ? resolve_type_expr(a, fc, texpr) : 0;
    spl_ir_node_ref_t v = 0;
    spl_type_id_t vt = 0;
    if (initexpr) {
        fc->hint = tid;
        v = lower_expr(a, fc, initexpr);
        fc->hint = 0;
        vt = node_type(fc, v);
        if (!tid && vt)
            tid = vt;
    }
    if (!tid)
        tid = kw_type(a, "void");
    spl_ir_node_ref_t slot = emit_alloca(a, fc, tid);
    if (v && vt && tid) {
        if (!type_same(a->sema, vt, tid))
            v = coerce_to(a, fc, v, vt, tid);
        emit_store(a, fc, tid, slot, v);
    }
    env_add(fc, name, def_id, tid, slot, 0, 0, 1);
}

static void lower_if(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_t *b) {
    spl_ir_node_ref_t c = lower_expr(a, fc, b->block_item.if_statement.expr);
    int has_else = b->block_item.if_statement.else_block.size > 0;
    usize then_b = new_block(fc);
    usize else_b = has_else ? new_block(fc) : 0;
    usize exit_b = new_block(fc);
    emit_br(a, fc, c, then_b, has_else ? else_b : exit_b);
    begin_block(fc, then_b);
    lower_block(a, fc, &b->block_item.if_statement.if_block);
    emit_jmp(a, fc, exit_b);
    if (has_else) {
        begin_block(fc, else_b);
        lower_block(a, fc, &b->block_item.if_statement.else_block);
        emit_jmp(a, fc, exit_b);
    }
    begin_block(fc, exit_b);
}

static void lower_while(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_t *b) {
    usize cond_b = new_block(fc);
    usize body_b = new_block(fc);
    usize exit_b = new_block(fc);
    begin_block(fc, cond_b);
    spl_ir_node_ref_t c = lower_expr(a, fc, b->block_item.while_statement.expr);
    emit_br(a, fc, c, body_b, exit_b);
    begin_block(fc, body_b);
    ir_loop_t lp = {exit_b, cond_b, fc->env.size};
    vec_push(fc->loops, lp);
    lower_block(a, fc, &b->block_item.while_statement.while_block);
    emit_jmp(a, fc, cond_b);
    vec_pop(fc->loops);
    begin_block(fc, exit_b);
}

static void lower_loop(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_t *b) {
    usize body_b = new_block(fc);
    usize exit_b = new_block(fc);
    begin_block(fc, body_b);
    ir_loop_t lp = {exit_b, body_b, fc->env.size};
    vec_push(fc->loops, lp);
    lower_block(a, fc, &b->block_item.loop_statement.loop_block);
    emit_jmp(a, fc, body_b);
    vec_pop(fc->loops);
    begin_block(fc, exit_b);
}

enum { FOR_RANGE, FOR_ARRAY, FOR_SLICE };
typedef struct {
    int kind;
    spl_type_id_t elem_tid;
    spl_ir_node_ref_t len;        /* 长度节点 = 无界 */
    spl_ir_node_ref_t begin_slot; /* range: begin */
    spl_ir_node_ref_t base_slot;  /* array/slice: 元素基址*/
} for_seq_t;

static void for_seq_setup(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_t eref, for_seq_t *s) {
    memset(s, 0, sizeof *s);
    spl_ast_node_t *n = node_at(a->sema, eref);
    if (n && n->kind == SPL_AST_EXPR && n->expr.op == SPL_AST_RANGE_EXPR) {
        s->kind = FOR_RANGE;
        spl_ir_node_ref_t beg = lower_expr(a, fc, n->expr.op_expr.left);
        s->elem_tid = underlying(a->sema, node_type(fc, beg));
        s->begin_slot = emit_alloca(a, fc, s->elem_tid);
        emit_store(a, fc, s->elem_tid, s->begin_slot, beg);
        if (n->expr.op_expr.right) {
            spl_ir_node_ref_t end = lower_expr(a, fc, n->expr.op_expr.right);
            spl_ir_node_ref_t b = emit_load(a, fc, s->elem_tid, s->begin_slot);
            s->len = emit_arith(a, fc, SPL_IR_ARITH_SUB, s->elem_tid,
                                coerce_to(a, fc, end, node_type(fc, end), s->elem_tid), b);
        }
        return;
    }
    spl_type_id_t bt = 0;
    spl_ir_node_ref_t base_lv = lower_lvalue(a, fc, eref, &bt);
    spl_type_node_t *tt = bt ? tn(a->sema, underlying(a->sema, bt)) : NULL;
    if (base_lv && tt && tt->kind == SPL_TYPE_ARRAY) {
        s->kind = FOR_ARRAY;
        s->elem_tid = tt->array_type.element;
        s->base_slot = base_lv;
        s->len = const_int(a, fc, kw_type(a, "usize"), tt->array_type.len);
        return;
    }
    if (base_lv && tt && tt->kind == SPL_TYPE_SLICE) {
        s->kind = FOR_SLICE;
        s->elem_tid = tt->slice_element;
        spl_ir_node_ref_t slv = emit_load(a, fc, bt, base_lv);
        spl_type_id_t ep = spl_type_ptr((spl_type_t *)&a->sema->type, s->elem_tid);
        s->base_slot = emit_alloca(a, fc, ep);
        s->len = emit_alloca(a, fc, kw_type(a, "usize"));
        emit_store(a, fc, ep, s->base_slot, emit_agg_extract(a, fc, bt, ep, 0, slv));
        emit_store(a, fc, kw_type(a, "usize"), s->len,
                   emit_agg_extract(a, fc, bt, kw_type(a, "usize"), 1, slv));
        return;
    }
    spl_ir_node_ref_t v = lower_expr(a, fc, eref);
    spl_type_id_t vt = underlying(a->sema, node_type(fc, v));
    spl_type_node_t *vtt = vt ? tn(a->sema, vt) : NULL;
    if (vtt && vtt->kind == SPL_TYPE_SLICE) {
        s->kind = FOR_SLICE;
        s->elem_tid = vtt->slice_element;
        spl_type_id_t ep = spl_type_ptr((spl_type_t *)&a->sema->type, s->elem_tid);
        s->base_slot = emit_alloca(a, fc, ep);
        s->len = emit_alloca(a, fc, kw_type(a, "usize"));
        emit_store(a, fc, ep, s->base_slot, emit_agg_extract(a, fc, vt, ep, 0, v));
        emit_store(a, fc, kw_type(a, "usize"), s->len,
                   emit_agg_extract(a, fc, vt, kw_type(a, "usize"), 1, v));
        return;
    }
    if (vtt && vtt->kind == SPL_TYPE_ARRAY) {
        spl_type_id_t fat = 0;
        spl_ir_node_ref_t faddr = lower_field_address(a, fc, eref, &fat);
        if (faddr) {
            s->kind = FOR_ARRAY;
            s->elem_tid = vtt->array_type.element;
            s->base_slot = faddr;
            s->len = const_int(a, fc, kw_type(a, "usize"), vtt->array_type.len);
            return;
        }
    }
    diag(a, fc, eref, "for: sequence must be Range/[]T/[N]T");
}

static void lower_for(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_t *b) {
    spl_ast_node_ref_vec_t *expr_vec = &b->block_item.for_statement.expr_vec;
    char **id_data = b->block_item.for_statement.ident_vec.data;
    usize id_size = b->block_item.for_statement.ident_vec.size;
    usize nseq = expr_vec->size;
    if (nseq != id_size || nseq > 8) {
        diag(a, fc, 0, "for: sequence/variable count mismatch");
        return;
    }
    for_seq_t seqs[8];
    for (usize i = 0; i < nseq; i++)
        for_seq_setup(a, fc, expr_vec->data[i], &seqs[i]);
    spl_type_id_t iszt = kw_type(a, "isize");
    spl_ir_node_ref_t min_slot = 0;
    int has_finite = 0;
    for (usize i = 0; i < nseq; i++)
        if (seqs[i].len)
            has_finite = 1;
    if (has_finite) {
        spl_ir_node_ref_t m = 0;
        for (usize i = 0; i < nseq; i++) {
            if (!seqs[i].len)
                continue;
            spl_ir_node_ref_t lenv = seqs[i].len;
            if (seqs[i].kind == FOR_SLICE)
                lenv = emit_load(a, fc, kw_type(a, "usize"), seqs[i].len);
            spl_ir_node_ref_t l = coerce_to(a, fc, lenv, node_type(fc, lenv), iszt);
            if (!m) {
                m = l;
            } else {
                spl_ir_node_ref_t c = emit_cmp(a, fc, SPL_IR_CMP_LT, iszt, l, m);
                m = emit_select(a, fc, iszt, c, l, m);
            }
        }
        min_slot = emit_alloca(a, fc, iszt);
        emit_store(a, fc, iszt, min_slot, m);
    }
    spl_ir_node_ref_t ctr = emit_alloca(a, fc, iszt);
    emit_store(a, fc, iszt, ctr, const_int(a, fc, iszt, 0));
    env_push(fc);
    for (usize i = 0; i < nseq; i++)
        env_add(fc, id_data[i], 0, seqs[i].elem_tid, 0, 0, 0, 0);
    usize cond_b = new_block(fc);
    usize body_b = new_block(fc);
    usize exit_b = new_block(fc);
    begin_block(fc, cond_b);
    if (has_finite) {
        spl_ir_node_ref_t cur = emit_load(a, fc, iszt, ctr);
        spl_ir_node_ref_t ml = emit_load(a, fc, iszt, min_slot);
        spl_ir_node_ref_t c = emit_cmp(a, fc, SPL_IR_CMP_LT, iszt, cur, ml);
        emit_br(a, fc, c, body_b, exit_b);
    } else {
        emit_jmp(a, fc, body_b);
    }
    begin_block(fc, body_b);
    for (usize i = 0; i < nseq; i++) {
        for_seq_t *s = &seqs[i];
        spl_ir_node_ref_t cur = emit_load(a, fc, iszt, ctr);
        spl_ir_node_ref_t v = 0;
        if (s->kind == FOR_RANGE) {
            spl_ir_node_ref_t bg = emit_load(a, fc, s->elem_tid, s->begin_slot);
            v = emit_arith(a, fc, SPL_IR_ARITH_ADD, s->elem_tid, bg,
                           coerce_to(a, fc, cur, iszt, s->elem_tid));
        } else {
            spl_ir_node_ref_t base = s->base_slot;
            if (s->kind == FOR_SLICE) {
                spl_type_id_t ep = spl_type_ptr((spl_type_t *)&a->sema->type, s->elem_tid);
                base = emit_load(a, fc, ep, s->base_slot);
            }
            spl_ir_node_ref_t addr = emit_offset(a, fc, s->elem_tid, base, cur);
            v = emit_load(a, fc, s->elem_tid, addr);
        }
        ir_env_t *it = env_find(fc, id_data[i]);
        if (it) {
            it->tid = s->elem_tid;
            it->value = v;
        }
    }
    ir_loop_t lp = {exit_b, cond_b, fc->env.size};
    vec_push(fc->loops, lp);
    lower_block(a, fc, &b->block_item.for_statement.block);
    spl_ir_node_ref_t cur2 = emit_load(a, fc, iszt, ctr);
    spl_ir_node_ref_t one = const_int(a, fc, iszt, 1);
    spl_ir_node_ref_t nxt = emit_arith(a, fc, SPL_IR_ARITH_ADD, iszt, cur2, one);
    emit_store(a, fc, iszt, ctr, nxt);
    emit_jmp(a, fc, cond_b);
    vec_pop(fc->loops);
    env_pop(fc);
    begin_block(fc, exit_b);
}

static void lower_ret(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_t *b) {
    emit_defers_from(a, fc, 0);
    if (b->block_item.ret_statement.expr) {
        fc->hint = fc->ret_tid;
        spl_ir_node_ref_t v = lower_expr(a, fc, b->block_item.ret_statement.expr);
        fc->hint = 0;
        spl_type_id_t vt = node_type(fc, v);
        if (fc->ret_tid && vt && !type_same(a->sema, vt, fc->ret_tid))
            v = coerce_to(a, fc, v, vt, fc->ret_tid);
        emit_ret(a, fc, fc->ret_tid, v);
    } else {
        emit_ret(a, fc, fc->ret_tid, 0);
    }
}

static void lower_match(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_t *b) {
    spl_ast_node_ref_vec_t *arms = &b->block_item.match_statement.paced_exprs;
    spl_ast_node_ref_vec_t *bodies = &b->block_item.match_statement.match_block;
    if (arms->size != bodies->size) {
        diag(a, fc, 0, "match: arm pattern/body count mismatch");
        return;
    }
    spl_ir_node_ref_t subj = lower_expr(a, fc, b->block_item.match_statement.expr);
    spl_type_id_t st = underlying(a->sema, node_type(fc, subj));
    spl_type_node_t *tt = tn(a->sema, st);
    if (tt && tt->kind == SPL_TYPE_PTR) {
        st = underlying(a->sema, tt->ptr_pointee);
        tt = tn(a->sema, st);
        subj = emit_load(a, fc, st, subj);
    }
    int is_enum = tt && tt->kind == SPL_TYPE_ENUM;
    int is_int = tt && tt->kind == SPL_TYPE_INT;
    if (!is_enum && !is_int) {
        diag(a, fc, 0, "match subject must be enum/union/integer");
        return;
    }
    spl_ir_node_ref_t subj_slot = emit_alloca(a, fc, st);
    emit_store(a, fc, st, subj_slot, subj);
    spl_type_id_t tag_t = enum_tag_tid(a);
    spl_ir_node_ref_t tag_slot = 0;
    if (is_enum) {
        spl_ir_node_ref_t tagv =
            emit_agg_extract(a, fc, st, tag_t, 0, emit_load(a, fc, st, subj_slot));
        tag_slot = emit_alloca(a, fc, tag_t);
        emit_store(a, fc, tag_t, tag_slot, tagv);
    }
    usize exit_b = new_block(fc);
    for (usize i = 0; i < arms->size; i++) {
        spl_ast_node_t *pk = node_at(a->sema, arms->data[i]);
        usize body_b = new_block(fc);
        usize next_b = (i + 1 < arms->size) ? new_block(fc) : 0;
        int is_default = !pk || (!pk->packed_expr.ident && !pk->packed_expr.expr);
        if (is_default) {
            emit_jmp(a, fc, body_b);
        } else {
            spl_ir_node_ref_t cond = 0;
            if (is_enum && pk->packed_expr.ident) {
                isize vidx = enum_variant_index(a, st, pk->packed_expr.ident);
                if (vidx < 0)
                    vidx = 0;
                spl_ir_node_ref_t tv = emit_load(a, fc, tag_t, tag_slot);
                spl_ir_node_ref_t idxc = const_int(a, fc, tag_t, (usize)vidx);
                cond = emit_cmp(a, fc, SPL_IR_CMP_EQ, tag_t, tv, idxc);
            } else if (is_int && pk->packed_expr.expr) {
                spl_ir_node_ref_t sv = emit_load(a, fc, st, subj_slot);
                spl_ir_node_ref_t pv = lower_expr(a, fc, pk->packed_expr.expr);
                pv = coerce_to(a, fc, pv, node_type(fc, pv), st);
                cond = emit_cmp(a, fc, SPL_IR_CMP_EQ, st, sv, pv);
            }
            if (cond)
                emit_br(a, fc, cond, body_b, next_b ? next_b : exit_b);
            else
                emit_jmp(a, fc, body_b);
        }
        begin_block(fc, body_b);
        env_push(fc);
        if (is_enum && pk && pk->packed_expr.ident && pk->packed_expr.bind_ident) {
            isize vidx = enum_variant_index(a, st, pk->packed_expr.ident);
            spl_type_id_t pt = enum_payload_tid(a, st, vidx);
            if (pt) {
                spl_ir_node_ref_t sv = emit_load(a, fc, st, subj_slot);
                /* enum 布局 = tag(0) + payload(8)：直接提<E68EA5>?payload，field_tid = 变体具体类型 */
                spl_ir_node_ref_t pv = emit_agg_extract(a, fc, st, pt, 1, sv);
                spl_ir_node_ref_t bslot = emit_alloca(a, fc, pt);
                emit_store(a, fc, pt, bslot, pv);
                env_add(fc, pk->packed_expr.bind_ident, 0, pt, bslot, 0, 0, 0);
            }
        }
        spl_ast_node_t *body = node_at(a->sema, bodies->data[i]);
        if (body && body->kind == SPL_AST_EXPR && body->expr.op == SPL_AST_PRIMARY_EXPR) {
            spl_ast_node_t *pn = node_at(a->sema, body->expr.op_expr.left);
            if (pn && pn->primary_expr.kind == SPL_AST_BLOCK_EXPR)
                lower_block(a, fc, &pn->primary_expr.block_expr);
            else
                lower_expr(a, fc, bodies->data[i]);
        } else {
            lower_expr(a, fc, bodies->data[i]);
        }
        env_pop(fc);
        emit_jmp(a, fc, exit_b);
        if (next_b)
            begin_block(fc, next_b);
    }
    begin_block(fc, exit_b);
}

static void lower_stmt(spl_ast2ir_t *a, fnctx_t *fc, spl_ast_node_ref_t ref) {
    spl_ast_node_t *b = node_at(a->sema, ref);
    if (!b)
        return;
    if (b->kind == SPL_AST_EXPR) {
        if (b->expr.op == SPL_AST_PRIMARY_EXPR) {
            spl_ast_node_t *pn = node_at(a->sema, b->expr.op_expr.left);
            if (pn && pn->primary_expr.kind == SPL_AST_BLOCK_EXPR) {
                lower_block_expr(a, fc, &pn->primary_expr.block_expr);
                return;
            }
        }
        lower_expr(a, fc, ref);
        return;
    }
    switch (b->block_item.kind) {
    case SPL_AST_VARDECL: {
        spl_ast_node_t *vd = node_at(a->sema, b->block_item.var_decl);
        if (vd)
            lower_var_decl(a, fc, vd->var_decl.name, vd->resolved_def_id, vd->var_decl.type_expr,
                           vd->var_decl.expr);
        break;
    }
    case SPL_AST_CONSTDECL: {
        spl_ast_node_t *cd = node_at(a->sema, b->block_item.const_decl);
        if (cd)
            lower_var_decl(a, fc, cd->const_decl.name, cd->resolved_def_id,
                           cd->const_decl.type_expr, cd->const_decl.expr);
        break;
    }
    case SPL_AST_TYPEDECL: {
        spl_ast_node_t *td = node_at(a->sema, b->block_item.type_decl);
        if (td)
            lower_type_decl(a, fc, td);
        break;
    }
    case SPL_AST_IF_STATEMENT:
        lower_if(a, fc, b);
        break;
    case SPL_AST_IFVAR_STATEMENT:
        diag(a, fc, ref, "if-var not supported");
        break;
    case SPL_AST_WHILE_STATEMENT:
        lower_while(a, fc, b);
        break;
    case SPL_AST_LOOP_STATEMENT:
        lower_loop(a, fc, b);
        break;
    case SPL_AST_FOR_STATEMENT:
        lower_for(a, fc, b);
        break;
    case SPL_AST_MATCH_STATEMENT:
        lower_match(a, fc, b);
        break;
    case SPL_AST_RET_STATEMENT:
        lower_ret(a, fc, b);
        break;
    case SPL_AST_BREAK_STATEMENT: {
        if (!fc->loops.size) {
            diag(a, fc, ref, "break outside loop");
            break;
        }
        ir_loop_t *lp = &fc->loops.data[fc->loops.size - 1];
        emit_defers_from(a, fc, lp->env_mark);
        emit_jmp(a, fc, lp->brk);
        break;
    }
    case SPL_AST_CONTINUE_STATEMENT: {
        if (!fc->loops.size) {
            diag(a, fc, ref, "continue outside loop");
            break;
        }
        ir_loop_t *lp = &fc->loops.data[fc->loops.size - 1];
        emit_defers_from(a, fc, lp->env_mark);
        emit_jmp(a, fc, lp->cont);
        break;
    }
    case SPL_AST_DEFER_STATEMENT:
        lower_defer(a, fc, ref);
        break;
    case SPL_AST_EXPR_STATEMENT:
        if (b->block_item.expr_statement)
            lower_expr(a, fc, b->block_item.expr_statement);
        break;
    default:
        break;
    }
}

/* ================================================================
 * 函数
 * ================================================================ */

static spl_ir_func_ref_t a2ir_fn_of(spl_ast2ir_t *a, spl_type_id_t fn_tid) {
    /* 懒扫描：IR func 已记<E5B7B2>?fn_tid（spl_type_fn 不去重，fn_tid 唯一<E594AF>?*/
    for (usize i = 1; i < a->ir.funcs.size; i++) {
        if (a->ir.funcs.data[i].fn_tid == fn_tid)
            return i;
    }
    return 0;
}

static void lower_func_body(spl_ast2ir_t *a, spl_ir_func_ref_t fid, spl_type_id_t fn_tid,
                            spl_ast_node_ref_t def_ref, spl_type_id_t ns_tid) {
    spl_ast_node_t *fn = node_at(a->sema, def_ref);
    if (!fn)
        return;
    spl_type_node_t *ft = tn(a->sema, fn_tid);
    spl_type_id_t ret = (ft && ft->kind == SPL_TYPE_FN) ? ft->fn_type.ret : 0;
    fnctx_t fc;
    fc_init_ns(&fc, a, fid, ret, ns_tid);
    spl_ast_node_ref_vec_t *pl = &fn->fn_decl.param_list;
    usize nparams = (ft && ft->kind == SPL_TYPE_FN) ? ft->fn_type.params.size : 0;
    env_push(&fc);
    for (usize i = 0; i < pl->size && i < nparams; i++) {
        spl_ast_node_t *pd = node_at(a->sema, pl->data[i]);
        if (!pd || !pd->param_decl.name)
            continue;
        spl_type_id_t pt = ft->fn_type.params.data[i];
        spl_ir_node_ref_t pr = emit_node(a, &fc);
        spl_ir_node_t *e = enode(a, &fc, pr);
        e->kind = SPL_IR_CONTROL_PARAM;
        e->control_param.tid = pt;
        e->control_param.idx = (usize)i;
        set_ntype(&fc, pr, pt);
        spl_ir_node_ref_t slot = emit_alloca(a, &fc, pt);
        emit_store(a, &fc, pt, slot, pr);
        env_add(&fc, pd->param_decl.name, pd->resolved_def_id, pt, slot, 0, 0, 0);
    }
    begin_block(&fc, new_block(&fc));
    lower_block(a, &fc, &fn->fn_decl.block);
    if (!fc.terminated)
        emit_ret(a, &fc, ret, 0);
    spl_ir_func_t *ff = spl_ir_func(&a->ir, fid);
    for (usize i = 0; i < fc.fixups.size; i++) {
        ir_fix_t *fx = &fc.fixups.data[i];
        spl_ir_node_t *nn = spl_ir_node(&a->ir, fid, fx->node);
        spl_ir_node_ref_t target = fc.blocks.data[fx->block].first;
        if (!target)
            target = ff->nodes.size ? ff->nodes.size - 1 : 0;
        if (fx->slot == 0)
            nn->control_br.true_label = target;
        else if (fx->slot == 1)
            nn->control_br.false_label = target;
        else
            nn->control_jmp.label = target;
    }
    for (usize i = 0; i < fc.blocks.size; i++)
        if (fc.blocks.data[i].first)
            vec_push(ff->labels, fc.blocks.data[i].first);
    for (usize i = 1; i < ff->labels.size; i++) {
        spl_ir_node_ref_t k = ff->labels.data[i];
        usize j = i;
        while (j > 0 && ff->labels.data[j - 1] > k) {
            ff->labels.data[j] = ff->labels.data[j - 1];
            j--;
        }
        ff->labels.data[j] = k;
    }
    if (fc.err)
        a->err_count += fc.err;
    fc_drop(&fc);
}

void spl_ast2ir_init(spl_ast2ir_t *ast2ir, const spl_sema_t *sema) {
    memset(ast2ir, 0, sizeof *ast2ir);
    ast2ir->sema = sema;
    spl_ir_init(&ast2ir->ir);
    vec_init(ast2ir->owned_names);
}

void spl_ast2ir_drop(spl_ast2ir_t *ast2ir) {
    for (usize i = 0; i < ast2ir->owned_names.size; i++)
        free(ast2ir->owned_names.data[i]);
    vec_free(ast2ir->owned_names);
    vec_free(ast2ir->gdata_ref);
    spl_ir_drop(&ast2ir->ir);
}

/* ================================================================
 * 全局数据（聚合类型下 / 顶层<E9A1B6>?var、const<73>?
 * ================================================================ */

/* 常量折叠：仅支持字面量（int/char/float/string/null）与一元负<E58583>?*/
typedef struct {
    int const_init;
    isize int_v;
    double float_v;
    const char *cstr_v;
} gfold_t;

static void fold_const_init(spl_ast2ir_t *a, spl_ast_node_ref_t ref, gfold_t *g) {
    spl_ast_node_t *n = node_at(a->sema, ref);
    if (!n || n->kind != SPL_AST_EXPR)
        return;
    if (n->expr.op == SPL_AST_PRIMARY_EXPR) {
        spl_ast_node_t *pn = node_at(a->sema, n->expr.op_expr.left);
        if (!pn)
            return;
        switch (pn->primary_expr.kind) {
        case SPL_AST_INTEGER:
            g->const_init = 1;
            g->int_v = pn->primary_expr.integer_expr;
            return;
        case SPL_AST_CHAR_LIT:
            g->const_init = 1;
            g->int_v = (isize)(unsigned char)pn->primary_expr.char_lit_expr;
            return;
        case SPL_AST_FLOAT:
            g->const_init = 1;
            g->float_v = pn->primary_expr.float_expr;
            return;
        case SPL_AST_NULL:
            g->const_init = 1;
            g->int_v = 0;
            return;
        case SPL_AST_STRING_LIT:
            g->const_init = 1;
            g->cstr_v = pn->primary_expr.string_lit_expr;
            return;
        default:
            return;
        }
    }
    if (n->expr.op == SPL_AST_PREFIX_EXPR) {
        spl_ast_node_t *pp = node_at(a->sema, n->expr.op_expr.left);
        if (pp && pp->prefix_expr.kind == SPL_AST_MINUS_EXPR) {
            fold_const_init(a, pp->prefix_expr.postfix_expr, g);
            if (g->const_init)
                g->int_v = -g->int_v;
        }
    }
}

static void collect_gdata_list(spl_ast2ir_t *a, spl_ast_node_ref_vec_t *members) {
    for (usize i = 0; i < members->size; i++) {
        spl_ast_node_t *m = node_at(a->sema, members->data[i]);
        if (!m)
            continue;
        const char *mname = NULL;
        spl_ast_node_ref_t iexpr = 0;
        if (m->kind == SPL_AST_VAR_DECL) {
            mname = m->var_decl.name;
            iexpr = m->var_decl.expr;
        } else if (m->kind == SPL_AST_CONST_DECL) {
            mname = m->const_decl.name;
            iexpr = m->const_decl.expr;
        } else {
            continue;
        }
        if (!mname || !m->resolved_def_id)
            continue;
        spl_def_node_t *d = def_at(a->sema, m->resolved_def_id);
        if (!d)
            continue;
        gfold_t g;
        memset(&g, 0, sizeof g);
        spl_type_id_t g_tid = d->type_id;
        if (iexpr)
            fold_const_init(a, iexpr, &g);
        /* 全局 value = type.const 节点（标量折叠值；聚合/无 init 零） */
        spl_ir_node_t v;
        memset(&v, 0, sizeof v);
        v.kind = SPL_IR_TYPE_CONST;
        v.type_const.tid = g_tid;
        spl_type_node_t *gt = tn(a->sema, underlying(a->sema, g_tid));
        if (g.const_init && gt && gt->kind == SPL_TYPE_INT)
            v.type_const.int_lit = (usize)g.int_v;
        else if (g.const_init && gt && gt->kind == SPL_TYPE_FLOAT)
            v.type_const.float_lit = g.float_v;
        else
            v.type_const.int_lit = 0;
        vec_push(a->ir.gdata, v);
        spl_ast2ir_gref_t gr = {m->resolved_def_id, a->ir.gdata.size - 1};
        vec_push(a->gdata_ref, gr);
    }
}

static void collect_gdata(spl_ast2ir_t *a) {
    spl_ast_node_t *root = node_at(a->sema, a->sema->ast->root);
    if (!root || root->kind != SPL_AST_CONTAINER_ITEM)
        return;
    collect_gdata_list(a, &root->container_item.members);
    for (usize i = 0; i < root->container_item.members.size; i++) {
        spl_ast_node_ref_t mref = root->container_item.members.data[i];
        spl_ast_node_t *m = node_at(a->sema, mref);
        if (!m || m->kind != SPL_AST_TYPE_DECL)
            continue;
        spl_ast_node_t *te = node_at(a->sema, m->type_decl.type_expr);
        if (!te ||
            (te->type_expr.kind != SPL_AST_TYPE_STRUCT &&
             te->type_expr.kind != SPL_AST_TYPE_UNION && te->type_expr.kind != SPL_AST_TYPE_ENUM))
            continue;
        collect_gdata_list(a, &te->type_expr.aggregate_list);
    }
}

/* def_id <20>?gdata value 节点索引；未命中返回 -1 */
static isize gdata_index_by_def(spl_ast2ir_t *a, spl_def_id_t def_id) {
    for (usize i = 0; i < a->gdata_ref.size; i++)
        if (a->gdata_ref.data[i].def_id == def_id)
            return (isize)a->gdata_ref.data[i].gdata_idx;
    return -1;
}

/* ================================================================
 * 预登记：为所有函数（顶层 + 聚合方法）建 IR func
 * ================================================================ */

/* 预登记：为所有函数（顶层 + 聚合方法）建 IR func */
static void register_funcs(spl_ast2ir_t *a) {
    spl_ast_node_t *root = node_at(a->sema, a->sema->ast->root);
    if (!root || root->kind != SPL_AST_CONTAINER_ITEM)
        return;
    for (usize i = 0; i < root->container_item.members.size; i++) {
        spl_ast_node_ref_t mref = root->container_item.members.data[i];
        spl_ast_node_t *m = node_at(a->sema, mref);
        if (!m || (m->kind != SPL_AST_FN_DECL && m->kind != SPL_AST_FN_DEFINE))
            continue;
        spl_def_id_t def = root_lookup(a, m->fn_decl.name);
        if (!def)
            continue;
        spl_type_id_t fn_tid = def_at(a->sema, def)->type_id;
        spl_ir_func_ref_t fid = spl_ir_alloc_fn(&a->ir);
        spl_ir_func_t *f = spl_ir_func(&a->ir, fid);
        f->name = m->fn_decl.name;
        f->fn_tid = fn_tid;
    }
    for (usize i = 0; i < root->container_item.members.size; i++) {
        spl_ast_node_ref_t mref = root->container_item.members.data[i];
        spl_ast_node_t *m = node_at(a->sema, mref);
        if (!m || m->kind != SPL_AST_TYPE_DECL)
            continue;
        spl_ast_node_t *te = node_at(a->sema, m->type_decl.type_expr);
        if (!te ||
            (te->type_expr.kind != SPL_AST_TYPE_STRUCT &&
             te->type_expr.kind != SPL_AST_TYPE_UNION && te->type_expr.kind != SPL_AST_TYPE_ENUM))
            continue;
        spl_def_id_t adef = root_lookup(a, m->type_decl.name);
        if (!adef)
            continue;
        spl_type_id_t agg_tid = underlying(a->sema, def_at(a->sema, adef)->type_id);
        for (usize j = 0; j < te->type_expr.aggregate_list.size; j++) {
            spl_ast_node_ref_t mm = te->type_expr.aggregate_list.data[j];
            spl_ast_node_t *mn = node_at(a->sema, mm);
            if (!mn || (mn->kind != SPL_AST_FN_DECL && mn->kind != SPL_AST_FN_DEFINE))
                continue;
            spl_type_id_t mt = agg_member_type(a, agg_tid, mn->fn_decl.name);
            if (!mt)
                continue;
            size_t nlen = strlen(m->type_decl.name) + 1 + strlen(mn->fn_decl.name) + 1;
            char *fname = malloc(nlen);
            snprintf(fname, nlen, "%s.%s", m->type_decl.name, mn->fn_decl.name);
            spl_ir_func_ref_t fid = spl_ir_alloc_fn(&a->ir);
            spl_ir_func_t *f = spl_ir_func(&a->ir, fid);
            f->name = fname;
            f->fn_tid = mt;
            vec_push(a->owned_names, fname);
        }
    }
}

void spl_ast2ir_run(spl_ast2ir_t *a) {
    spl_ast_node_t *root = node_at(a->sema, a->sema->ast->root);
    if (!root || root->kind != SPL_AST_CONTAINER_ITEM)
        return;
    vec_init(a->gdata_ref);
    collect_gdata(a);
    register_funcs(a);
    for (usize i = 0; i < root->container_item.members.size; i++) {
        spl_ast_node_ref_t mref = root->container_item.members.data[i];
        spl_ast_node_t *m = node_at(a->sema, mref);
        if (!m || m->kind != SPL_AST_FN_DEFINE)
            continue;
        spl_def_id_t def = root_lookup(a, m->fn_decl.name);
        if (!def)
            continue;
        spl_type_id_t fn_tid = def_at(a->sema, def)->type_id;
        spl_ir_func_ref_t fid = a2ir_fn_of(a, fn_tid);
        if (fid)
            lower_func_body(a, fid, fn_tid, mref, 0);
    }
    for (usize i = 0; i < root->container_item.members.size; i++) {
        spl_ast_node_ref_t mref = root->container_item.members.data[i];
        spl_ast_node_t *m = node_at(a->sema, mref);
        if (!m || m->kind != SPL_AST_TYPE_DECL)
            continue;
        spl_ast_node_t *te = node_at(a->sema, m->type_decl.type_expr);
        if (!te ||
            (te->type_expr.kind != SPL_AST_TYPE_STRUCT &&
             te->type_expr.kind != SPL_AST_TYPE_UNION && te->type_expr.kind != SPL_AST_TYPE_ENUM))
            continue;
        spl_def_id_t adef = root_lookup(a, m->type_decl.name);
        if (!adef)
            continue;
        spl_type_id_t agg_tid = underlying(a->sema, def_at(a->sema, adef)->type_id);
        for (usize j = 0; j < te->type_expr.aggregate_list.size; j++) {
            spl_ast_node_ref_t mm = te->type_expr.aggregate_list.data[j];
            spl_ast_node_t *mn = node_at(a->sema, mm);
            if (!mn || mn->kind != SPL_AST_FN_DEFINE)
                continue;
            spl_type_id_t mt = agg_member_type(a, agg_tid, mn->fn_decl.name);
            spl_ir_func_ref_t fid = mt ? a2ir_fn_of(a, mt) : 0;
            if (fid)
                lower_func_body(a, fid, mt, mm, agg_tid);
        }
    }
}