test: 新增 codegen 层单元测试 (7 tests)

- test_codegen.c: 构造 AST → codegen_module → LLVMVerifyModule
- 覆盖: 函数+返回字面量, if/else 分支, 二元运算(1+2*3)
- 总单元测试: 41+15+9+7 = 72
- 基于 Codex 分析报告 §5-4 技术债务补偿

CMakeLists.txt

@@ -92,3 +92,13 @@ target_include_directories(l_lang_sema_test PRIVATE
     src/util src/lexer src/ast src/parser src/sema src/codegen src/driver
     test
 )
+
+# Codegen 测试
+add_executable(l_lang_codegen_test test/test_codegen.c)
+target_link_libraries(l_lang_codegen_test PRIVATE l_lang_lib)
+target_include_directories(l_lang_codegen_test PRIVATE
+    ${CMAKE_SOURCE_DIR}/include
+    ${LLVM_INCLUDE_DIRS}
+    src/util src/lexer src/ast src/parser src/sema src/codegen src/driver
+    test
+)

test/test_codegen.c

@@ -0,0 +1,96 @@
+#include "test_utils.h"
+#include "codegen.h"
+#include "ast.h"
+#include "arena.h"
+#include <llvm-c/Analysis.h>
+
+void test_codegen_simple_function() {
+    Arena a = arena_create(1);
+
+    // 构造 AST: fn main() -> i64 { return 42; }
+    AstNode* ret = ast_make_return(&a, ast_make_literal_i64(&a, 42, 1, 1), 1, 1);
+    AstNode* stmts[] = { ret };
+    AstNode* body = ast_make_block(&a, stmts, 1, 1, 1);
+    AstNode* fn = ast_make_function(&a, "main", NULL, 0, TYPE_I64, body, 1, 1);
+    AstNode* fns[] = { fn };
+    AstNode* prog = ast_make_program(&a, fns, 1, 1, 1);
+
+    const char* err = NULL;
+    LLVMModuleRef mod = codegen_module(prog, &a, "test_mod", &err);
+    ASSERT(mod != NULL);
+    ASSERT(err == NULL);
+
+    // 验证模块
+    char* verify_err = NULL;
+    int failed = LLVMVerifyModule(mod, LLVMReturnStatusAction, &verify_err);
+    ASSERT(!failed);
+
+    LLVMDisposeModule(mod);
+    arena_destroy(&a);
+}
+
+void test_codegen_if_else() {
+    Arena a = arena_create(1);
+
+    // fn main() -> i64 { if true { return 1; } else { return 0; } }
+    AstNode* then_ret = ast_make_return(&a, ast_make_literal_i64(&a, 1, 1, 1), 1, 1);
+    AstNode* then_stmts[] = { then_ret };
+    AstNode* then_block = ast_make_block(&a, then_stmts, 1, 1, 1);
+    AstNode* else_ret = ast_make_return(&a, ast_make_literal_i64(&a, 0, 1, 1), 1, 1);
+    AstNode* else_stmts[] = { else_ret };
+    AstNode* else_block = ast_make_block(&a, else_stmts, 1, 1, 1);
+    AstNode* if_stmt = ast_make_if(&a,
+        ast_make_literal_bool(&a, true, 1, 1), then_block, else_block, 1, 1);
+    AstNode* stmts[] = { if_stmt };
+    AstNode* body = ast_make_block(&a, stmts, 1, 1, 1);
+    AstNode* fn = ast_make_function(&a, "main", NULL, 0, TYPE_I64, body, 1, 1);
+    AstNode* fns[] = { fn };
+    AstNode* prog = ast_make_program(&a, fns, 1, 1, 1);
+
+    const char* err = NULL;
+    LLVMModuleRef mod = codegen_module(prog, &a, "test_mod2", &err);
+    ASSERT(mod != NULL);
+
+    char* verify_err = NULL;
+    int failed = LLVMVerifyModule(mod, LLVMReturnStatusAction, &verify_err);
+    ASSERT(!failed);
+
+    LLVMDisposeModule(mod);
+    arena_destroy(&a);
+}
+
+void test_codegen_binary_ops() {
+    Arena a = arena_create(1);
+
+    // fn main() -> i64 { return 1 + 2 * 3; }
+    AstNode* expr = ast_make_binary(&a, OP_ADD,
+        ast_make_literal_i64(&a, 1, 1, 1),
+        ast_make_binary(&a, OP_MUL,
+            ast_make_literal_i64(&a, 2, 1, 1),
+            ast_make_literal_i64(&a, 3, 1, 1), 1, 1),
+        1, 1);
+    AstNode* ret = ast_make_return(&a, expr, 1, 1);
+    AstNode* stmts[] = { ret };
+    AstNode* body = ast_make_block(&a, stmts, 1, 1, 1);
+    AstNode* fn = ast_make_function(&a, "main", NULL, 0, TYPE_I64, body, 1, 1);
+    AstNode* fns[] = { fn };
+    AstNode* prog = ast_make_program(&a, fns, 1, 1, 1);
+
+    const char* err = NULL;
+    LLVMModuleRef mod = codegen_module(prog, &a, "test_mod3", &err);
+    ASSERT(mod != NULL);
+
+    char* verify_err = NULL;
+    int failed = LLVMVerifyModule(mod, LLVMReturnStatusAction, &verify_err);
+    ASSERT(!failed);
+
+    LLVMDisposeModule(mod);
+    arena_destroy(&a);
+}
+
+int main(void) {
+    TEST_RUN(test_codegen_simple_function);
+    TEST_RUN(test_codegen_if_else);
+    TEST_RUN(test_codegen_binary_ops);
+    return test_summary();
+}