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feat: 列表推导式 [for x in arr: expr] — parser+sema+codegen

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AST(29): +AST_LIST_COMP, parser 解析 [for var in expr: body]
sema: 创建子作用域注册循环变量, codegen: for 循环绑定+填充结果数组
已知限制: 仅支持 2 元素及以下数组 (大数组 alloca 对齐问题待修)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
This commit is contained in:
刘航宇
2026-06-07 13:58:54 +08:00
parent 0088347576
commit 443b22bdf1
6 changed files with 128 additions and 0 deletions
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src/codegen/cg_expr.c
+69
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@@ -403,6 +403,74 @@ CG_HANDLER(cg_if_expr)
// === Visitor Dispatch 表 ===
static AstDispatch cg_dispatch;
static LLVMValueRef cg_list_comp_impl(CgCtx* ctx, AstNode* node) {
TypeInfo* ti = &node->type;
LLVMTypeRef elem_ty = type_info_to_llvm(ctx, ti);
LLVMTypeRef arr_ty = LLVMArrayType(elem_ty, (unsigned)ti->array_size);
LLVMValueRef result = LLVMBuildAlloca(ctx->builder, arr_ty, "list");
// 初始化为零
LLVMBuildStore(ctx->builder, LLVMConstNull(arr_ty), result);
// 获取源数组指针 (需要 alloca 做 GEP, 不能用 load 后的值)
LLVMValueRef src_ptr = NULL;
if (node->as.list_comp.array->kind == AST_IDENT_EXPR) {
src_ptr = find_var(ctx, node->as.list_comp.array->as.ident.name);
}
if (!src_ptr) return NULL;
// for i in 0 to N
LLVMValueRef func = LLVMGetBasicBlockParent(LLVMGetInsertBlock(ctx->builder));
LLVMBasicBlockRef cond_bb = LLVMAppendBasicBlockInContext(ctx->context, func, "lc_cond");
LLVMBasicBlockRef body_bb = LLVMAppendBasicBlockInContext(ctx->context, func, "lc_body");
LLVMBasicBlockRef exit_bb = LLVMAppendBasicBlockInContext(ctx->context, func, "lc_exit");
// 循环变量 i
LLVMValueRef i_alloca = LLVMBuildAlloca(ctx->builder,
LLVMInt64TypeInContext(ctx->context), "lc_i");
LLVMBuildStore(ctx->builder,
LLVMConstInt(LLVMInt64TypeInContext(ctx->context), 0, false), i_alloca);
LLVMBuildBr(ctx->builder, cond_bb);
// 条件块
LLVMPositionBuilderAtEnd(ctx->builder, cond_bb);
LLVMValueRef i_val = LLVMBuildLoad2(ctx->builder,
LLVMInt64TypeInContext(ctx->context), i_alloca, "i");
LLVMValueRef end_val = LLVMConstInt(LLVMInt64TypeInContext(ctx->context),
(unsigned long long)ti->array_size, false);
LLVMValueRef cond = LLVMBuildICmp(ctx->builder, LLVMIntSLT, i_val, end_val, "lc_cond");
LLVMBuildCondBr(ctx->builder, cond, body_bb, exit_bb);
// 循环体
LLVMPositionBuilderAtEnd(ctx->builder, body_bb);
LLVMValueRef i32_trunc = LLVMBuildTrunc(ctx->builder, i_val,
LLVMInt32TypeInContext(ctx->context), "i32");
// 绑定循环变量: var x = arr[i]
LLVMValueRef src_indices[] = {
LLVMConstInt(LLVMInt32TypeInContext(ctx->context), 0, false), i32_trunc
};
LLVMValueRef src_gep = LLVMBuildGEP2(ctx->builder, arr_ty, src_ptr, src_indices, 2, "src_gep");
LLVMValueRef var_alloca = LLVMBuildAlloca(ctx->builder, elem_ty,
node->as.list_comp.var_name);
LLVMBuildStore(ctx->builder,
LLVMBuildLoad2(ctx->builder, elem_ty, src_gep, "src_val"), var_alloca);
add_var(ctx, node->as.list_comp.var_name, var_alloca, elem_ty);
// map 表达式（可引用循环变量）
LLVMValueRef map_val = codegen_expr(ctx, node->as.list_comp.map_expr);
if (!map_val) return NULL;
// 结果数组: GEP + store
LLVMValueRef dst_indices[] = {
LLVMConstInt(LLVMInt32TypeInContext(ctx->context), 0, false),
LLVMBuildTrunc(ctx->builder, i_val,
LLVMInt32TypeInContext(ctx->context), "i32")
};
LLVMBuildStore(ctx->builder, map_val,
LLVMBuildGEP2(ctx->builder, arr_ty, result, dst_indices, 2, "dst_ptr"));
// i = i + 1
LLVMValueRef next_i = LLVMBuildAdd(ctx->builder, i_val,
LLVMConstInt(LLVMInt64TypeInContext(ctx->context), 1, false), "i_inc");
LLVMBuildStore(ctx->builder, next_i, i_alloca);
LLVMBuildBr(ctx->builder, cond_bb);
// 出口
LLVMPositionBuilderAtEnd(ctx->builder, exit_bb);
return LLVMBuildLoad2(ctx->builder, arr_ty, result, "list_val");
}
CG_HANDLER(cg_list_comp)
void codegen_expr_init(void) {
ast_dispatch_set(&cg_dispatch, AST_LITERAL_EXPR, cg_literal);
ast_dispatch_set(&cg_dispatch, AST_IDENT_EXPR, cg_ident);
@@ -416,6 +484,7 @@ void codegen_expr_init(void) {
ast_dispatch_set(&cg_dispatch, AST_INDEX_EXPR, cg_index);
ast_dispatch_set(&cg_dispatch, AST_BLOCK, cg_block);
ast_dispatch_set(&cg_dispatch, AST_IF_STMT, cg_if_expr);
ast_dispatch_set(&cg_dispatch, AST_LIST_COMP, cg_list_comp);
}
// === 统一入口 ===