12.8 切片 2：全局数据区与 I/Q/M（LOAD/STORE 指令）。

- 数据区布局：声明序 + 对齐（BOOL 1B/INT 2B/TIME 8B），初值入数据段
- 读全局 LOAD_GLOBAL / io.input 绑定用 LOAD_I；写 STORE_GLOBAL / io.output 用 STORE_Q；写 io.input 拒绝
- 临时寄存器分配：语句内递增、语句结束复用基址
- codegen_test：51 断言（用例 09 初值+LOAD_GLOBAL、io 绑定 LOAD_I/STORE_Q、混合布局偏移、写输入负例），ctest 9/9

tests/src/codegen_test.cpp

@@ -7,6 +7,7 @@
 
 #include <cstdio>
 #include <cstring>
+#include <filesystem>
 #include <string>
 #include <vector>
 
@@ -58,6 +59,50 @@ static bool compile_case(const char* dir, std::vector<uint8_t>* image, std::stri
     return codegen_project(p, units, link, image, err);
 }
 
+// 从临时工程（globals.st + main.st + 可含 io 绑定）走完整管线
+static bool compile_src(const char* name, const char* io_extra, const char* globals_st,
+                        const char* main_st, std::vector<uint8_t>* image,
+                        std::string* err) {
+    using namespace compiler;
+    const std::string dir = std::string(REPO_ROOT) + "/build/cg_tmp_" + name;
+    std::filesystem::remove_all(dir);
+    std::filesystem::create_directories(dir);
+    const std::string toml_path = dir + "/project.toml";
+    std::FILE* f = std::fopen(toml_path.c_str(), "w");
+    std::fprintf(f, "[project]\nname = \"cg\"\nentry = \"program MAIN\"\n"
+                    "cycle_limit = 1000\ndt_ms = 10\n"
+                    "[files]\nst = [\"globals.st\", \"main.st\"]\n"
+                    "[gvl]\nfile = \"globals.st\"\n%s", io_extra);
+    std::fclose(f);
+    f = std::fopen((dir + "/globals.st").c_str(), "w");
+    std::fputs(globals_st, f);
+    std::fclose(f);
+    f = std::fopen((dir + "/main.st").c_str(), "w");
+    std::fputs(main_st, f);
+    std::fclose(f);
+
+    Project p;
+    if (!parse_project(toml_path, &p, err)) {
+        return false;
+    }
+    std::vector<SourceUnit> units;
+    for (const std::string& file : compile_files(p)) {
+        SourceUnit u;
+        if (!load_unit(p.base_dir + "/" + file, &u, err)) {
+            return false;
+        }
+        units.push_back(std::move(u));
+    }
+    LinkResult link;
+    if (!link_project(p, units, &link, err)) {
+        return false;
+    }
+    if (!check_project(p, units, link, err)) {
+        return false;
+    }
+    return codegen_project(p, units, link, image, err);
+}
+
 // ---- 1. 用例 01：空 MAIN + RET ----
 
 static bool test_case01() {
@@ -119,9 +164,128 @@ static bool test_case02() {
     return true;
 }
 
+// ---- 3. 用例 09：GVL + VAR_EXTERNAL（全局读取 LOAD_GLOBAL + 初值数据段）----
+
+static bool test_case09() {
+    std::vector<uint8_t> img;
+    std::string err;
+    CHECK(compile_case("09_gvl_external", &img, &err));
+
+    const isa::ImageView v = isa::ImageView::from(img);
+    CHECK(v.ok());
+    CHECK(v.header().n_globals == 1);
+    CHECK(v.data_len() == 2);                       // INT 2 字节
+    CHECK(v.data_bytes()[0] == 5);                  // G1 初值 5（小端低位）
+    CHECK(v.data_bytes()[1] == 0);
+
+    const isa::FuncRow r = v.func_row(0);
+    CHECK(r.nregs == 1);                            // 仅局部 x
+    CHECK(r.code_len == 2);
+
+    char buf[64];
+    const uint8_t* base = v.code_bytes();
+    isa::disasm(reinterpret_cast<const uint32_t*>(base)[0], buf, sizeof buf);
+    CHECK(std::strcmp(buf, "LOAD_GLOBAL r0, 0") == 0);  // x := G1（槽 0 偏移 0）
+    isa::disasm(reinterpret_cast<const uint32_t*>(base)[1], buf, sizeof buf);
+    CHECK(std::strcmp(buf, "RET") == 0);
+    return true;
+}
+
+// ---- 4. io 绑定：LOAD_I / STORE_Q ----
+
+static bool test_io_ops() {
+    std::vector<uint8_t> img;
+    std::string err;
+    const char* io_extra =
+        "[[io.input]]\nvar = \"I0_0\"\nchannel = 0\nbit = 0\n"
+        "[[io.output]]\nvar = \"Q0_0\"\nchannel = 0\nbit = 0\n";
+    const char* globals_st =
+        "VAR_GLOBAL\n    I0_0 : BOOL;\n    Q0_0 : BOOL;\nEND_VAR\n";
+    const char* main_st =
+        "PROGRAM MAIN\nVAR\n    q : BOOL;\nEND_VAR\n"
+        "    q := I0_0;\n"
+        "    Q0_0 := q;\n"
+        "END_PROGRAM\n";
+    CHECK(compile_src("io", io_extra, globals_st, main_st, &img, &err));
+
+    const isa::ImageView v = isa::ImageView::from(img);
+    CHECK(v.ok());
+    CHECK(v.header().n_globals == 2);
+
+    const isa::FuncRow r = v.func_row(0);
+    CHECK(r.nregs == 2);                            // q + 1 临时
+
+    char buf[64];
+    const uint8_t* base = v.code_bytes();
+    isa::disasm(reinterpret_cast<const uint32_t*>(base)[0], buf, sizeof buf);
+    CHECK(std::strcmp(buf, "LOAD_I r0, 0") == 0);   // q := I0_0（io.input → LOAD_I）
+    isa::disasm(reinterpret_cast<const uint32_t*>(base)[1], buf, sizeof buf);
+    CHECK(std::strcmp(buf, "MOVE r1, r0") == 0);    // 临时 ← q
+    isa::disasm(reinterpret_cast<const uint32_t*>(base)[2], buf, sizeof buf);
+    CHECK(std::strcmp(buf, "STORE_Q r1, 1") == 0);  // Q0_0 := 临时（io.output → STORE_Q）
+    isa::disasm(reinterpret_cast<const uint32_t*>(base)[3], buf, sizeof buf);
+    CHECK(std::strcmp(buf, "RET") == 0);
+    return true;
+}
+
+// ---- 5. 混合类型布局：BOOL@0 INT@2 TIME@8，初值入数据段 ----
+
+static bool test_layout() {
+    std::vector<uint8_t> img;
+    std::string err;
+    const char* globals_st =
+        "VAR_GLOBAL\n"
+        "    B : BOOL;\n"
+        "    I : INT := 300;\n"
+        "    T : TIME := T#10ms;\n"
+        "END_VAR\n";
+    const char* main_st =
+        "PROGRAM MAIN\nVAR\n    x : INT;\nEND_VAR\n"
+        "    x := I;\n"
+        "END_PROGRAM\n";
+    CHECK(compile_src("layout", "", globals_st, main_st, &img, &err));
+
+    const isa::ImageView v = isa::ImageView::from(img);
+    CHECK(v.ok());
+    CHECK(v.header().n_globals == 3);
+    CHECK(v.data_len() == 16);                      // 0 + 2 + 8（对齐）= 16
+    CHECK(v.data_bytes()[0] == 0);                  // B 无初值
+    CHECK(v.data_bytes()[2] == 0x2C && v.data_bytes()[3] == 0x01);  // I = 300
+    CHECK(v.data_bytes()[8] == 10);                 // T = 10ms
+
+    char buf[64];
+    isa::disasm(reinterpret_cast<const uint32_t*>(v.code_bytes())[0], buf, sizeof buf);
+    CHECK(std::strcmp(buf, "LOAD_GLOBAL r0, 2") == 0);  // x := I（INT 偏移 2）
+    return true;
+}
+
+// ---- 6. 写 io.input → codegen error ----
+
+static bool test_write_input() {
+    std::vector<uint8_t> img;
+    std::string err;
+    const char* io_extra =
+        "[[io.input]]\nvar = \"I0_0\"\nchannel = 0\nbit = 0\n";
+    const char* globals_st =
+        "VAR_GLOBAL\n    I0_0 : BOOL;\nEND_VAR\n";
+    const char* main_st =
+        "PROGRAM MAIN\n    I0_0 := TRUE;\nEND_PROGRAM\n";
+    if (compile_src("winput", io_extra, globals_st, main_st, &img, &err)) {
+        std::printf("FAIL write_input: codegen passed\n");
+        return false;
+    }
+    CHECK(err.find("codegen error") == 0);
+    CHECK(err.find("cannot write to input") != std::string::npos);
+    return true;
+}
+
 int main() {
     if (!test_case01()) return 1;
     if (!test_case02()) return 1;
+    if (!test_case09()) return 1;
+    if (!test_io_ops()) return 1;
+    if (!test_layout()) return 1;
+    if (!test_write_input()) return 1;
     std::printf("codegen_test: %d checks passed\n", g_checks);
     return 0;
 }