top-level-await support - follow the spec in the implementation of the module linking and evaluation to avoid errors with cycling module dependencies

1 files changed, 625 insertions, 87 deletions

diff --git a/lib/quickjs/quickjs.c b/lib/quickjs/quickjs.c
index ef71029a..258807e4 100644
--- a/lib/quickjs/quickjs.c
+++ b/lib/quickjs/quickjs.c
@@ -285,7 +285,9 @@ struct JSRuntime {
     JSModuleNormalizeFunc *module_normalize_func;
     JSModuleLoaderFunc *module_loader_func;
     void *module_loader_opaque;
-
+    /* timestamp for internal use in module evaluation */
+    int64_t module_async_evaluation_next_timestamp;
+    
     BOOL can_block : 8; /* TRUE if Atomics.wait can block */
     /* used to allocate, free and clone SharedArrayBuffers */
     JSSharedArrayBufferFunctions sab_funcs;
@@ -769,6 +771,15 @@ typedef struct JSImportEntry {
     int req_module_idx; /* in req_module_entries */
 } JSImportEntry;
 
+typedef enum {
+    JS_MODULE_STATUS_UNLINKED,
+    JS_MODULE_STATUS_LINKING,
+    JS_MODULE_STATUS_LINKED,
+    JS_MODULE_STATUS_EVALUATING,
+    JS_MODULE_STATUS_EVALUATING_ASYNC,
+    JS_MODULE_STATUS_EVALUATED,
+} JSModuleStatus;
+
 struct JSModuleDef {
     JSRefCountHeader header; /* must come first, 32-bit */
     JSAtom module_name;
@@ -793,11 +804,24 @@ struct JSModuleDef {
     JSValue module_ns;
     JSValue func_obj; /* only used for JS modules */
     JSModuleInitFunc *init_func; /* only used for C modules */
+    BOOL has_tla : 8; /* true if func_obj contains await */
     BOOL resolved : 8;
     BOOL func_created : 8;
-    BOOL instantiated : 8;
-    BOOL evaluated : 8;
-    BOOL eval_mark : 8; /* temporary use during js_evaluate_module() */
+    JSModuleStatus status : 8;
+    /* temp use during js_module_link() & js_module_evaluate() */
+    int dfs_index, dfs_ancestor_index;
+    JSModuleDef *stack_prev;
+    /* temp use during js_module_evaluate() */
+    JSModuleDef **async_parent_modules;
+    int async_parent_modules_count;
+    int async_parent_modules_size;
+    int pending_async_dependencies;
+    BOOL async_evaluation;
+    int64_t async_evaluation_timestamp;
+    JSModuleDef *cycle_root;
+    JSValue promise; /* corresponds to spec field: capability */
+    JSValue resolving_funcs[2]; /* corresponds to spec field: capability */
+    
     /* true if evaluation yielded an exception. It is saved in
        eval_exception */
     BOOL eval_has_exception : 8; 
@@ -1202,6 +1226,8 @@ static __exception int perform_promise_then(JSContext *ctx,
                                             JSValueConst *cap_resolving_funcs);
 static JSValue js_promise_resolve(JSContext *ctx, JSValueConst this_val,
                                   int argc, JSValueConst *argv, int magic);
+static JSValue js_promise_then(JSContext *ctx, JSValueConst this_val,
+                               int argc, JSValueConst *argv);
 static int js_string_compare(JSContext *ctx,
                              const JSString *p1, const JSString *p2);
 static JSValue JS_ToNumber(JSContext *ctx, JSValueConst val);
@@ -2200,7 +2226,6 @@ JSValue JS_GetClassProto(JSContext *ctx, JSClassID class_id)
 typedef enum JSFreeModuleEnum {
     JS_FREE_MODULE_ALL,
     JS_FREE_MODULE_NOT_RESOLVED,
-    JS_FREE_MODULE_NOT_EVALUATED,
 } JSFreeModuleEnum;
 
 /* XXX: would be more efficient with separate module lists */
@@ -2210,8 +2235,7 @@ static void js_free_modules(JSContext *ctx, JSFreeModuleEnum flag)
     list_for_each_safe(el, el1, &ctx->loaded_modules) {
         JSModuleDef *m = list_entry(el, JSModuleDef, link);
         if (flag == JS_FREE_MODULE_ALL ||
-            (flag == JS_FREE_MODULE_NOT_RESOLVED && !m->resolved) ||
-            (flag == JS_FREE_MODULE_NOT_EVALUATED && !m->evaluated)) {
+            (flag == JS_FREE_MODULE_NOT_RESOLVED && !m->resolved)) {
             js_free_module_def(ctx, m);
         }
     }
@@ -19836,6 +19860,7 @@ typedef struct JSFunctionDef {
     int source_len;
 
     JSModuleDef *module; /* != NULL when parsing a module */
+    BOOL has_await; /* TRUE if await is used (used in module eval) */
 } JSFunctionDef;
 
 typedef struct JSToken {
@@ -24894,6 +24919,7 @@ static __exception int js_parse_unary(JSParseState *s, int parse_flags)
             return -1;
         if (js_parse_unary(s, PF_POW_FORBIDDEN))
             return -1;
+        s->cur_func->has_await = TRUE;
         emit_op(s, OP_await);
         parse_flags = 0;
         break;
@@ -26293,6 +26319,7 @@ static __exception int js_parse_statement_or_decl(JSParseState *s,
                 is_async = TRUE;
                 if (next_token(s))
                     goto fail;
+                s->cur_func->has_await = TRUE;
             }
             if (js_parse_expect(s, '('))
                 goto fail;
@@ -26823,6 +26850,9 @@ static JSModuleDef *js_new_module_def(JSContext *ctx, JSAtom name)
     m->func_obj = JS_UNDEFINED;
     m->eval_exception = JS_UNDEFINED;
     m->meta_obj = JS_UNDEFINED;
+    m->promise = JS_UNDEFINED;
+    m->resolving_funcs[0] = JS_UNDEFINED;
+    m->resolving_funcs[1] = JS_UNDEFINED;
     list_add_tail(&m->link, &ctx->loaded_modules);
     return m;
 }
@@ -26844,6 +26874,9 @@ static void js_mark_module_def(JSRuntime *rt, JSModuleDef *m,
     JS_MarkValue(rt, m->func_obj, mark_func);
     JS_MarkValue(rt, m->eval_exception, mark_func);
     JS_MarkValue(rt, m->meta_obj, mark_func);
+    JS_MarkValue(rt, m->promise, mark_func);
+    JS_MarkValue(rt, m->resolving_funcs[0], mark_func);
+    JS_MarkValue(rt, m->resolving_funcs[1], mark_func);
 }
 
 static void js_free_module_def(JSContext *ctx, JSModuleDef *m)
@@ -26874,11 +26907,15 @@ static void js_free_module_def(JSContext *ctx, JSModuleDef *m)
         JS_FreeAtom(ctx, mi->import_name);
     }
     js_free(ctx, m->import_entries);
+    js_free(ctx, m->async_parent_modules);
 
     JS_FreeValue(ctx, m->module_ns);
     JS_FreeValue(ctx, m->func_obj);
     JS_FreeValue(ctx, m->eval_exception);
     JS_FreeValue(ctx, m->meta_obj);
+    JS_FreeValue(ctx, m->promise);
+    JS_FreeValue(ctx, m->resolving_funcs[0]);
+    JS_FreeValue(ctx, m->resolving_funcs[1]);
     list_del(&m->link);
     js_free(ctx, m);
 }
@@ -27734,7 +27771,8 @@ static int js_create_module_function(JSContext *ctx, JSModuleDef *m)
     
 /* Prepare a module to be executed by resolving all the imported
    variables. */
-static int js_link_module(JSContext *ctx, JSModuleDef *m)
+static int js_inner_module_linking(JSContext *ctx, JSModuleDef *m,
+                                   JSModuleDef **pstack_top, int index)
 {
     int i;
     JSImportEntry *mi;
@@ -27744,21 +27782,47 @@ static int js_link_module(JSContext *ctx, JSModuleDef *m)
     BOOL is_c_module;
     JSValue ret_val;
     
-    if (m->instantiated)
-        return 0;
-    m->instantiated = TRUE;
-
+    if (js_check_stack_overflow(ctx->rt, 0)) {
+        JS_ThrowStackOverflow(ctx);
+        return -1;
+    }
+    
 #ifdef DUMP_MODULE_RESOLVE
     {
         char buf1[ATOM_GET_STR_BUF_SIZE];
-        printf("start instantiating module '%s':\n", JS_AtomGetStr(ctx, buf1, sizeof(buf1), m->module_name));
+        printf("js_inner_module_linking '%s':\n", JS_AtomGetStr(ctx, buf1, sizeof(buf1), m->module_name));
     }
 #endif
 
+    if (m->status == JS_MODULE_STATUS_LINKING ||
+        m->status == JS_MODULE_STATUS_LINKED ||
+        m->status == JS_MODULE_STATUS_EVALUATING_ASYNC ||
+        m->status == JS_MODULE_STATUS_EVALUATED)
+        return index;
+
+    assert(m->status == JS_MODULE_STATUS_UNLINKED);
+    m->status = JS_MODULE_STATUS_LINKING;
+    m->dfs_index = index;
+    m->dfs_ancestor_index = index;
+    index++;
+    /* push 'm' on stack */
+    m->stack_prev = *pstack_top;
+    *pstack_top = m;
+
     for(i = 0; i < m->req_module_entries_count; i++) {
         JSReqModuleEntry *rme = &m->req_module_entries[i];
-        if (js_link_module(ctx, rme->module) < 0)
+        m1 = rme->module;
+        index = js_inner_module_linking(ctx, m1, pstack_top, index);
+        if (index < 0)
             goto fail;
+        assert(m1->status == JS_MODULE_STATUS_LINKING ||
+               m1->status == JS_MODULE_STATUS_LINKED ||
+               m1->status == JS_MODULE_STATUS_EVALUATING_ASYNC ||
+               m1->status == JS_MODULE_STATUS_EVALUATED);
+        if (m1->status == JS_MODULE_STATUS_LINKING) {
+            m->dfs_ancestor_index = min_int(m->dfs_ancestor_index,
+                                            m1->dfs_ancestor_index);
+        }
     }
 
 #ifdef DUMP_MODULE_RESOLVE
@@ -27884,14 +27948,59 @@ static int js_link_module(JSContext *ctx, JSModuleDef *m)
         JS_FreeValue(ctx, ret_val);
     }
 
+    assert(m->dfs_ancestor_index <= m->dfs_index);
+    if (m->dfs_index == m->dfs_ancestor_index) {
+        for(;;) {
+            /* pop m1 from stack */
+            m1 = *pstack_top;
+            *pstack_top = m1->stack_prev;
+            m1->status = JS_MODULE_STATUS_LINKED;
+            if (m1 == m)
+                break;
+        }
+    }
+
 #ifdef DUMP_MODULE_RESOLVE
-    printf("done instantiate\n");
+    printf("js_inner_module_linking done\n");
 #endif
-    return 0;
+    return index;
  fail:
     return -1;
 }
 
+/* Prepare a module to be executed by resolving all the imported
+   variables. */
+static int js_link_module(JSContext *ctx, JSModuleDef *m)
+{
+    JSModuleDef *stack_top, *m1;
+
+#ifdef DUMP_MODULE_RESOLVE
+    {
+        char buf1[ATOM_GET_STR_BUF_SIZE];
+        printf("js_link_module '%s':\n", JS_AtomGetStr(ctx, buf1, sizeof(buf1), m->module_name));
+    }
+#endif
+    assert(m->status == JS_MODULE_STATUS_UNLINKED ||
+           m->status == JS_MODULE_STATUS_LINKED ||
+           m->status == JS_MODULE_STATUS_EVALUATING_ASYNC ||
+           m->status == JS_MODULE_STATUS_EVALUATED);
+    stack_top = NULL;
+    if (js_inner_module_linking(ctx, m, &stack_top, 0) < 0) {
+        while (stack_top != NULL) {
+            m1 = stack_top;
+            assert(m1->status == JS_MODULE_STATUS_LINKING);
+            m1->status = JS_MODULE_STATUS_UNLINKED;
+            stack_top = m1->stack_prev;
+        }
+        return -1;
+    }
+    assert(stack_top == NULL);
+    assert(m->status == JS_MODULE_STATUS_LINKED ||
+           m->status == JS_MODULE_STATUS_EVALUATING_ASYNC ||
+           m->status == JS_MODULE_STATUS_EVALUATED);
+    return 0;
+}
+
 /* return JS_ATOM_NULL if the name cannot be found. Only works with
    not striped bytecode functions. */
 JSAtom JS_GetScriptOrModuleName(JSContext *ctx, int n_stack_levels)
@@ -27961,29 +28070,110 @@ static JSValue js_import_meta(JSContext *ctx)
     return JS_GetImportMeta(ctx, m);
 }
 
-/* used by os.Worker() and import() */
-JSModuleDef *JS_RunModule(JSContext *ctx, const char *basename,
-                          const char *filename)
+static JSValue JS_NewModuleValue(JSContext *ctx, JSModuleDef *m)
+{
+    return JS_DupValue(ctx, JS_MKPTR(JS_TAG_MODULE, m));
+}
+
+static JSValue js_load_module_rejected(JSContext *ctx, JSValueConst this_val,
+                                       int argc, JSValueConst *argv, int magic, JSValue *func_data)
 {
+    JSValueConst *resolving_funcs = (JSValueConst *)func_data;
+    JSValueConst error;
+    JSValue ret;
+    
+    /* XXX: check if the test is necessary */
+    if (argc >= 1)
+        error = argv[0];
+    else
+        error = JS_UNDEFINED;
+    ret = JS_Call(ctx, resolving_funcs[1], JS_UNDEFINED,
+                  1, &error);
+    JS_FreeValue(ctx, ret);
+    return JS_UNDEFINED;
+}
+
+static JSValue js_load_module_fulfilled(JSContext *ctx, JSValueConst this_val,
+                                        int argc, JSValueConst *argv, int magic, JSValue *func_data)
+{
+    JSValueConst *resolving_funcs = (JSValueConst *)func_data;
+    JSModuleDef *m = JS_VALUE_GET_PTR(func_data[2]);
+    JSValue ret, ns;
+    
+    /* return the module namespace */
+    ns = js_get_module_ns(ctx, m);
+    if (JS_IsException(ns)) {
+        JSValue err = JS_GetException(ctx);
+        js_load_module_rejected(ctx, JS_UNDEFINED, 1, (JSValueConst *)&err, 0, func_data);
+        return JS_UNDEFINED;
+    }
+    ret = JS_Call(ctx, resolving_funcs[0], JS_UNDEFINED,
+                   1, (JSValueConst *)&ns);
+    JS_FreeValue(ctx, ret);
+    JS_FreeValue(ctx, ns);
+    return JS_UNDEFINED;
+}
+
+static void JS_LoadModuleInternal(JSContext *ctx, const char *basename,
+                                  const char *filename,
+                                  JSValueConst *resolving_funcs)
+{
+    JSValue evaluate_promise;
     JSModuleDef *m;
-    JSValue ret, func_obj;
+    JSValue ret, err, func_obj, evaluate_resolving_funcs[2];
+    JSValueConst func_data[3];
     
     m = js_host_resolve_imported_module(ctx, basename, filename);
     if (!m)
-        return NULL;
+        goto fail;
     
     if (js_resolve_module(ctx, m) < 0) {
         js_free_modules(ctx, JS_FREE_MODULE_NOT_RESOLVED);
-        return NULL;
+        goto fail;
     }
 
     /* Evaluate the module code */
-    func_obj = JS_DupValue(ctx, JS_MKPTR(JS_TAG_MODULE, m));
-    ret = JS_EvalFunction(ctx, func_obj);
-    if (JS_IsException(ret))
-        return NULL;
+    func_obj = JS_NewModuleValue(ctx, m);
+    evaluate_promise = JS_EvalFunction(ctx, func_obj);
+    if (JS_IsException(evaluate_promise)) {
+    fail:
+        err = JS_GetException(ctx);
+        ret = JS_Call(ctx, resolving_funcs[1], JS_UNDEFINED,
+                      1, (JSValueConst *)&err);
+        JS_FreeValue(ctx, ret); /* XXX: what to do if exception ? */
+        JS_FreeValue(ctx, err);
+        return;
+    }
+
+    func_obj = JS_NewModuleValue(ctx, m);
+    func_data[0] = resolving_funcs[0];
+    func_data[1] = resolving_funcs[1];
+    func_data[2] = func_obj;
+    evaluate_resolving_funcs[0] = JS_NewCFunctionData(ctx, js_load_module_fulfilled, 0, 0, 3, func_data);
+    evaluate_resolving_funcs[1] = JS_NewCFunctionData(ctx, js_load_module_rejected, 0, 0, 3, func_data);
+    JS_FreeValue(ctx, func_obj);
+    ret = js_promise_then(ctx, evaluate_promise, 2, (JSValueConst *)evaluate_resolving_funcs);
     JS_FreeValue(ctx, ret);
-    return m;
+    JS_FreeValue(ctx, evaluate_resolving_funcs[0]);
+    JS_FreeValue(ctx, evaluate_resolving_funcs[1]);
+    JS_FreeValue(ctx, evaluate_promise);
+}
+
+/* Return a promise or an exception in case of memory error. Used by
+   os.Worker() */
+JSValue JS_LoadModule(JSContext *ctx, const char *basename,
+                      const char *filename)
+{
+    JSValue promise, resolving_funcs[2];
+    
+    promise = JS_NewPromiseCapability(ctx, resolving_funcs);
+    if (JS_IsException(promise))
+        return JS_EXCEPTION;
+    JS_LoadModuleInternal(ctx, basename, filename,
+                          (JSValueConst *)resolving_funcs);
+    JS_FreeValue(ctx, resolving_funcs[0]);
+    JS_FreeValue(ctx, resolving_funcs[1]);
+    return promise;
 }
 
 static JSValue js_dynamic_import_job(JSContext *ctx,
@@ -27992,9 +28182,8 @@ static JSValue js_dynamic_import_job(JSContext *ctx,
     JSValueConst *resolving_funcs = argv;
     JSValueConst basename_val = argv[2];
     JSValueConst specifier = argv[3];
-    JSModuleDef *m;
     const char *basename = NULL, *filename;
-    JSValue ret, err, ns;
+    JSValue ret, err;
 
     if (!JS_IsString(basename_val)) {
         JS_ThrowTypeError(ctx, "no function filename for import()");
@@ -28008,24 +28197,12 @@ static JSValue js_dynamic_import_job(JSContext *ctx,
     if (!filename)
         goto exception;
                      
-    m = JS_RunModule(ctx, basename, filename);
+    JS_LoadModuleInternal(ctx, basename, filename,
+                          resolving_funcs);
     JS_FreeCString(ctx, filename);
-    if (!m)
-        goto exception;
-
-    /* return the module namespace */
-    ns = js_get_module_ns(ctx, m);
-    if (JS_IsException(ns))
-        goto exception;
-
-    ret = JS_Call(ctx, resolving_funcs[0], JS_UNDEFINED,
-                   1, (JSValueConst *)&ns);
-    JS_FreeValue(ctx, ret); /* XXX: what to do if exception ? */
-    JS_FreeValue(ctx, ns);
     JS_FreeCString(ctx, basename);
     return JS_UNDEFINED;
  exception:
-
     err = JS_GetException(ctx);
     ret = JS_Call(ctx, resolving_funcs[1], JS_UNDEFINED,
                    1, (JSValueConst *)&err);
@@ -28061,6 +28238,8 @@ static JSValue js_dynamic_import(JSContext *ctx, JSValueConst specifier)
     args[2] = basename_val;
     args[3] = specifier;
     
+    /* cannot run JS_LoadModuleInternal synchronously because it would
+       cause an unexpected recursion in js_evaluate_module() */
     JS_EnqueueJob(ctx, js_dynamic_import_job, 4, args);
 
     JS_FreeValue(ctx, basename_val);
@@ -28069,60 +28248,397 @@ static JSValue js_dynamic_import(JSContext *ctx, JSValueConst specifier)
     return promise;
 }
 
-/* Run the <eval> function of the module and of all its requested
-   modules. */
-static JSValue js_evaluate_module(JSContext *ctx, JSModuleDef *m)
+static void js_set_module_evaluated(JSContext *ctx, JSModuleDef *m)
+{
+    m->status = JS_MODULE_STATUS_EVALUATED;
+    if (!JS_IsUndefined(m->promise)) {
+        JSValue value, ret_val;
+        assert(m->cycle_root == m);
+        value = JS_UNDEFINED;
+        ret_val = JS_Call(ctx, m->resolving_funcs[0], JS_UNDEFINED,
+                          1, (JSValueConst *)&value);
+        JS_FreeValue(ctx, ret_val);
+    }
+}
+
+typedef struct {
+    JSModuleDef **tab;
+    int count;
+    int size;
+} ExecModuleList;
+
+/* XXX: slow. Could use a linked list instead of ExecModuleList */
+static BOOL find_in_exec_module_list(ExecModuleList *exec_list, JSModuleDef *m)
+{
+    int i;
+    for(i = 0; i < exec_list->count; i++) {
+        if (exec_list->tab[i] == m)
+            return TRUE;
+    }
+    return FALSE;
+}
+
+static int gather_available_ancestors(JSContext *ctx, JSModuleDef *module,
+                                      ExecModuleList *exec_list)
+{
+    int i;
+
+    if (js_check_stack_overflow(ctx->rt, 0)) {
+        JS_ThrowStackOverflow(ctx);
+        return -1;
+    }
+    for(i = 0; i < module->async_parent_modules_count; i++) {
+        JSModuleDef *m = module->async_parent_modules[i];
+        if (!find_in_exec_module_list(exec_list, m) &&
+            !m->cycle_root->eval_has_exception) {
+            assert(m->status == JS_MODULE_STATUS_EVALUATING_ASYNC);
+            assert(!m->eval_has_exception);
+            assert(m->async_evaluation);
+            assert(m->pending_async_dependencies > 0);
+            m->pending_async_dependencies--;
+            if (m->pending_async_dependencies == 0) {
+                if (js_resize_array(ctx, (void **)&exec_list->tab, sizeof(exec_list->tab[0]), &exec_list->size, exec_list->count + 1)) {
+                    return -1;
+                }
+                exec_list->tab[exec_list->count++] = m;
+                if (!m->has_tla) {
+                    if (gather_available_ancestors(ctx, m, exec_list))
+                        return -1;
+                }
+            }
+        }
+    }
+    return 0;
+}
+
+static int exec_module_list_cmp(const void *p1, const void *p2, void *opaque)
+{
+    JSModuleDef *m1 = *(JSModuleDef **)p1;
+    JSModuleDef *m2 = *(JSModuleDef **)p2;
+    return (m1->async_evaluation_timestamp > m2->async_evaluation_timestamp) -
+        (m1->async_evaluation_timestamp < m2->async_evaluation_timestamp);
+}
+
+static int js_execute_async_module(JSContext *ctx, JSModuleDef *m);
+static int js_execute_sync_module(JSContext *ctx, JSModuleDef *m,
+                                  JSValue *pvalue);
+
+static JSValue js_async_module_execution_rejected(JSContext *ctx, JSValueConst this_val,
+                                                  int argc, JSValueConst *argv, int magic, JSValue *func_data)
+{
+    JSModuleDef *module = JS_VALUE_GET_PTR(func_data[0]);
+    JSValueConst error = argv[0];
+    int i;
+    
+    if (js_check_stack_overflow(ctx->rt, 0))
+        return JS_ThrowStackOverflow(ctx);
+
+    if (module->status == JS_MODULE_STATUS_EVALUATED) {
+        assert(module->eval_has_exception);
+        return JS_UNDEFINED;
+    }
+
+    assert(module->status == JS_MODULE_STATUS_EVALUATING_ASYNC);
+    assert(!module->eval_has_exception);
+    assert(module->async_evaluation);
+
+    module->eval_has_exception = TRUE;
+    module->eval_exception = JS_DupValue(ctx, error);
+    module->status = JS_MODULE_STATUS_EVALUATED;
+
+    for(i = 0; i < module->async_parent_modules_count; i++) {
+        JSModuleDef *m = module->async_parent_modules[i];
+        JSValue m_obj = JS_NewModuleValue(ctx, m);
+        js_async_module_execution_rejected(ctx, JS_UNDEFINED, 1, &error, 0,
+                                           &m_obj);
+        JS_FreeValue(ctx, m_obj);
+    }
+
+    if (!JS_IsUndefined(module->promise)) {
+        JSValue ret_val;
+        assert(module->cycle_root == module);
+        ret_val = JS_Call(ctx, module->resolving_funcs[1], JS_UNDEFINED,
+                          1, &error);
+        JS_FreeValue(ctx, ret_val);
+    }
+    return JS_UNDEFINED;
+}
+
+static JSValue js_async_module_execution_fulfilled(JSContext *ctx, JSValueConst this_val,
+                                                   int argc, JSValueConst *argv, int magic, JSValue *func_data)
+{
+    JSModuleDef *module = JS_VALUE_GET_PTR(func_data[0]);
+    ExecModuleList exec_list_s, *exec_list = &exec_list_s;
+    int i;
+    
+    if (module->status == JS_MODULE_STATUS_EVALUATED) {
+        assert(module->eval_has_exception);
+        return JS_UNDEFINED;
+    }
+    assert(module->status == JS_MODULE_STATUS_EVALUATING_ASYNC);
+    assert(!module->eval_has_exception);
+    assert(module->async_evaluation);
+    module->async_evaluation = FALSE;
+    js_set_module_evaluated(ctx, module);
+
+    exec_list->tab = NULL;
+    exec_list->count = 0;
+    exec_list->size = 0;
+
+    if (gather_available_ancestors(ctx, module, exec_list) < 0) {
+        js_free(ctx, exec_list->tab);
+        return JS_EXCEPTION;
+    }
+
+    /* sort by increasing async_evaluation timestamp */
+    rqsort(exec_list->tab, exec_list->count, sizeof(exec_list->tab[0]),
+           exec_module_list_cmp, NULL);
+    
+    for(i = 0; i < exec_list->count; i++) {
+        JSModuleDef *m = exec_list->tab[i];
+        if (m->status == JS_MODULE_STATUS_EVALUATED) {
+            assert(m->eval_has_exception);
+        } else if (m->has_tla) {
+            js_execute_async_module(ctx, m);
+        } else {
+            JSValue error;
+            if (js_execute_sync_module(ctx, m, &error) < 0) {
+                JSValue m_obj = JS_NewModuleValue(ctx, m);
+                js_async_module_execution_rejected(ctx, JS_UNDEFINED,
+                                                   1, (JSValueConst *)&error, 0,
+                                                   &m_obj);
+                JS_FreeValue(ctx, m_obj);
+                JS_FreeValue(ctx, error);
+            } else {
+                js_set_module_evaluated(ctx, m);
+            }
+        }
+    }
+    js_free(ctx, exec_list->tab);
+    return JS_UNDEFINED;
+}
+
+static int js_execute_async_module(JSContext *ctx, JSModuleDef *m)
+{
+    JSValue promise, m_obj;
+    JSValue resolve_funcs[2], ret_val;
+    promise = js_async_function_call(ctx, m->func_obj, JS_UNDEFINED, 0, NULL, 0);
+    if (JS_IsException(promise))
+        return -1;
+    m_obj = JS_NewModuleValue(ctx, m);
+    resolve_funcs[0] = JS_NewCFunctionData(ctx, js_async_module_execution_fulfilled, 0, 0, 1, (JSValueConst *)&m_obj);
+    resolve_funcs[1] = JS_NewCFunctionData(ctx, js_async_module_execution_rejected, 0, 0, 1, (JSValueConst *)&m_obj);
+    ret_val = js_promise_then(ctx, promise, 2, (JSValueConst *)resolve_funcs);
+    JS_FreeValue(ctx, ret_val);
+    JS_FreeValue(ctx, m_obj);
+    JS_FreeValue(ctx, resolve_funcs[0]);
+    JS_FreeValue(ctx, resolve_funcs[1]);
+    JS_FreeValue(ctx, promise);
+    return 0;
+}
+
+/* return < 0 in case of exception. *pvalue contains the exception. */
+static int js_execute_sync_module(JSContext *ctx, JSModuleDef *m,
+                                  JSValue *pvalue)
+{
+    if (m->init_func) {
+        /* C module init : no asynchronous execution */
+        if (m->init_func(ctx, m) < 0)
+            goto fail;
+    } else {
+        JSValue promise;
+        JSPromiseStateEnum state;
+
+        promise = js_async_function_call(ctx, m->func_obj, JS_UNDEFINED, 0, NULL, 0);
+        if (JS_IsException(promise))
+            goto fail;
+        state = JS_PromiseState(ctx, promise);
+        if (state == JS_PROMISE_FULFILLED) {
+            JS_FreeValue(ctx, promise);
+        } else if (state == JS_PROMISE_REJECTED) {
+            *pvalue = JS_PromiseResult(ctx, promise);
+            JS_FreeValue(ctx, promise);
+            return -1;
+        } else {
+            JS_FreeValue(ctx, promise);
+            JS_ThrowTypeError(ctx, "promise is pending");
+        fail:
+            *pvalue = JS_GetException(ctx);
+            return -1;
+        }
+    }
+    *pvalue = JS_UNDEFINED;
+    return 0;
+}
+
+/* spec: InnerModuleEvaluation. Return (index, JS_UNDEFINED) or (-1,
+   exception) */
+static int js_inner_module_evaluation(JSContext *ctx, JSModuleDef *m,
+                                      int index, JSModuleDef **pstack_top,
+                                      JSValue *pvalue)
 {
     JSModuleDef *m1;
     int i;
-    JSValue ret_val;
 
-    if (m->eval_mark)
-        return JS_UNDEFINED; /* avoid cycles */
+    if (js_check_stack_overflow(ctx->rt, 0)) {
+        JS_ThrowStackOverflow(ctx);
+        *pvalue = JS_GetException(ctx);
+        return -1;
+    }
+    
+#ifdef DUMP_MODULE_RESOLVE
+    {
+        char buf1[ATOM_GET_STR_BUF_SIZE];
+        printf("js_inner_module_evaluation '%s':\n", JS_AtomGetStr(ctx, buf1, sizeof(buf1), m->module_name));
+    }
+#endif
 
-    if (m->evaluated) {
-        /* if the module was already evaluated, rethrow the exception
-           it raised */
+    if (m->status == JS_MODULE_STATUS_EVALUATING_ASYNC ||
+        m->status == JS_MODULE_STATUS_EVALUATED) {
         if (m->eval_has_exception) {
-            return JS_Throw(ctx, JS_DupValue(ctx, m->eval_exception));
+            *pvalue = JS_DupValue(ctx, m->eval_exception);
+            return -1;
         } else {
-            return JS_UNDEFINED;
+            *pvalue = JS_UNDEFINED;
+            return index;
         }
     }
+    if (m->status == JS_MODULE_STATUS_EVALUATING) {
+        *pvalue = JS_UNDEFINED;
+        return index;
+    }
+    assert(m->status == JS_MODULE_STATUS_LINKED);
 
-    m->eval_mark = TRUE;
-
+    m->status = JS_MODULE_STATUS_EVALUATING;
+    m->dfs_index = index;
+    m->dfs_ancestor_index = index;
+    m->pending_async_dependencies = 0;
+    index++;
+    /* push 'm' on stack */
+    m->stack_prev = *pstack_top;
+    *pstack_top = m;
+    
     for(i = 0; i < m->req_module_entries_count; i++) {
         JSReqModuleEntry *rme = &m->req_module_entries[i];
         m1 = rme->module;
-        if (!m1->eval_mark) {
-            ret_val = js_evaluate_module(ctx, m1);
-            if (JS_IsException(ret_val)) {
-                m->eval_mark = FALSE;
-                return ret_val;
+        index = js_inner_module_evaluation(ctx, m1, index, pstack_top, pvalue);
+        if (index < 0) 
+            return -1;
+        assert(m1->status == JS_MODULE_STATUS_EVALUATING ||
+               m1->status == JS_MODULE_STATUS_EVALUATING_ASYNC ||
+               m1->status == JS_MODULE_STATUS_EVALUATED);
+        if (m1->status == JS_MODULE_STATUS_EVALUATING) {
+            m->dfs_ancestor_index = min_int(m->dfs_ancestor_index,
+                                            m1->dfs_ancestor_index);
+        } else {
+            m1 = m1->cycle_root;
+            assert(m1->status == JS_MODULE_STATUS_EVALUATING_ASYNC ||
+                   m1->status == JS_MODULE_STATUS_EVALUATED);
+            if (m1->eval_has_exception) {
+                *pvalue = JS_DupValue(ctx, m1->eval_exception);
+                return -1;
             }
-            JS_FreeValue(ctx, ret_val);
+        }
+        if (m1->async_evaluation) {
+            m->pending_async_dependencies++;
+            if (js_resize_array(ctx, (void **)&m1->async_parent_modules, sizeof(m1->async_parent_modules[0]), &m1->async_parent_modules_size, m1->async_parent_modules_count + 1)) {
+                *pvalue = JS_GetException(ctx);
+                return -1;
+            }
+            m1->async_parent_modules[m1->async_parent_modules_count++] = m;
         }
     }
 
-    if (m->init_func) {
-        /* C module init */
-        if (m->init_func(ctx, m) < 0)
-            ret_val = JS_EXCEPTION;
-        else
-            ret_val = JS_UNDEFINED;
+    if (m->pending_async_dependencies > 0) {
+        assert(!m->async_evaluation);
+        m->async_evaluation = TRUE;
+        m->async_evaluation_timestamp =
+            ctx->rt->module_async_evaluation_next_timestamp++;
+    } else if (m->has_tla) {
+        assert(!m->async_evaluation);
+        m->async_evaluation = TRUE;
+        m->async_evaluation_timestamp =
+            ctx->rt->module_async_evaluation_next_timestamp++;
+        js_execute_async_module(ctx, m);
     } else {
-        ret_val = JS_CallFree(ctx, m->func_obj, JS_UNDEFINED, 0, NULL);
-        m->func_obj = JS_UNDEFINED;
+        if (js_execute_sync_module(ctx, m, pvalue) < 0)
+            return -1;
     }
-    if (JS_IsException(ret_val)) {
-        /* save the thrown exception value */
-        m->eval_has_exception = TRUE;
-        m->eval_exception = JS_DupValue(ctx, ctx->rt->current_exception);
+
+    assert(m->dfs_ancestor_index <= m->dfs_index);
+    if (m->dfs_index == m->dfs_ancestor_index) {
+        for(;;) {
+            /* pop m1 from stack */
+            m1 = *pstack_top;
+            *pstack_top = m1->stack_prev;
+            if (!m1->async_evaluation) {
+                m1->status = JS_MODULE_STATUS_EVALUATED;
+            } else {
+                m1->status = JS_MODULE_STATUS_EVALUATING_ASYNC;
+            }
+            /* spec bug: cycle_root must be assigned before the test */
+            m1->cycle_root = m;
+            if (m1 == m)
+                break;
+        }
     }
-    m->eval_mark = FALSE;
-    m->evaluated = TRUE;
-    return ret_val;
+    *pvalue = JS_UNDEFINED;
+    return index;
+}
+
+/* Run the <eval> function of the module and of all its requested
+   modules. Return a promise or an exception. */
+static JSValue js_evaluate_module(JSContext *ctx, JSModuleDef *m)
+{
+    JSModuleDef *m1, *stack_top;
+    JSValue ret_val, result;
+
+    assert(m->status == JS_MODULE_STATUS_LINKED ||
+           m->status == JS_MODULE_STATUS_EVALUATING_ASYNC ||
+           m->status == JS_MODULE_STATUS_EVALUATED);
+    if (m->status == JS_MODULE_STATUS_EVALUATING_ASYNC ||
+        m->status == JS_MODULE_STATUS_EVALUATED) {
+        m = m->cycle_root;
+    }
+    /* a promise may be created only on the cycle_root of a cycle */
+    if (!JS_IsUndefined(m->promise))
+        return JS_DupValue(ctx, m->promise);
+    m->promise = JS_NewPromiseCapability(ctx, m->resolving_funcs);
+    if (JS_IsException(m->promise))
+        return JS_EXCEPTION;
+
+    stack_top = NULL;
+    if (js_inner_module_evaluation(ctx, m, 0, &stack_top, &result) < 0) {
+        while (stack_top != NULL) {
+            m1 = stack_top;
+            assert(m1->status == JS_MODULE_STATUS_EVALUATING);
+            m1->status = JS_MODULE_STATUS_EVALUATED;
+            m1->eval_has_exception = TRUE;
+            m1->eval_exception = JS_DupValue(ctx, result);
+            m1->cycle_root = m; /* spec bug: should be present */
+            stack_top = m1->stack_prev;
+        }
+        JS_FreeValue(ctx, result);
+        assert(m->status == JS_MODULE_STATUS_EVALUATED);
+        assert(m->eval_has_exception);
+        ret_val = JS_Call(ctx, m->resolving_funcs[1], JS_UNDEFINED,
+                          1, (JSValueConst *)&m->eval_exception);
+        JS_FreeValue(ctx, ret_val);
+    } else {
+        assert(m->status == JS_MODULE_STATUS_EVALUATING_ASYNC ||
+               m->status == JS_MODULE_STATUS_EVALUATED);
+        assert(!m->eval_has_exception);
+        if (!m->async_evaluation) {
+            JSValue value;
+            assert(m->status == JS_MODULE_STATUS_EVALUATED);
+            value = JS_UNDEFINED;
+            ret_val = JS_Call(ctx, m->resolving_funcs[0], JS_UNDEFINED,
+                              1, (JSValueConst *)&value);
+            JS_FreeValue(ctx, ret_val);
+        }
+        assert(stack_top == NULL);
+    }
+    return JS_DupValue(ctx, m->promise);
 }
 
 static __exception JSAtom js_parse_from_clause(JSParseState *s)
@@ -33337,7 +33853,7 @@ static __exception int js_parse_program(JSParseState *s)
 
         emit_op(s, OP_return);
     } else {
-        emit_op(s, OP_return_undef);
+        emit_return(s, FALSE);
     }
 
     return 0;
@@ -33380,7 +33896,6 @@ static JSValue JS_EvalFunctionInternal(JSContext *ctx, JSValue fun_obj,
         ret_val = js_evaluate_module(ctx, m);
         if (JS_IsException(ret_val)) {
         fail:
-            js_free_modules(ctx, JS_FREE_MODULE_NOT_EVALUATED);
             return JS_EXCEPTION;
         }
     } else {
@@ -33493,6 +34008,10 @@ static JSValue __JS_EvalInternal(JSContext *ctx, JSValueConst this_obj,
             goto fail;
     }
     fd->module = m;
+    if (m != NULL) {
+        fd->in_function_body = TRUE;
+        fd->func_kind = JS_FUNC_ASYNC;
+    }
     s->is_module = (m != NULL);
     s->allow_html_comments = !s->is_module;
 
@@ -33507,6 +34026,9 @@ static JSValue __JS_EvalInternal(JSContext *ctx, JSValueConst this_obj,
         goto fail1;
     }
 
+    if (m != NULL)
+        m->has_tla = fd->has_await;
+
     /* create the function object and all the enclosed functions */
     fun_obj = js_create_function(ctx, fd);
     if (JS_IsException(fun_obj))
@@ -33516,7 +34038,7 @@ static JSValue __JS_EvalInternal(JSContext *ctx, JSValueConst this_obj,
         m->func_obj = fun_obj;
         if (js_resolve_module(ctx, m) < 0)
             goto fail1;
-        fun_obj = JS_DupValue(ctx, JS_MKPTR(JS_TAG_MODULE, m));
+        fun_obj = JS_NewModuleValue(ctx, m);
     }
     if (flags & JS_EVAL_FLAG_COMPILE_ONLY) {
         ret_val = fun_obj;
@@ -34262,6 +34784,8 @@ static int JS_WriteModule(BCWriterState *s, JSValueConst obj)
         bc_put_atom(s, mi->import_name);
         bc_put_leb128(s, mi->req_module_idx);
     }
+
+    bc_put_u8(s, m->has_tla);
     
     if (JS_WriteObjectRec(s, m->func_obj))
         goto fail;
@@ -35273,7 +35797,7 @@ static JSValue JS_ReadModule(BCReaderState *s)
     m = js_new_module_def(ctx, module_name);
     if (!m)
         goto fail;
-    obj = JS_DupValue(ctx, JS_MKPTR(JS_TAG_MODULE, m));
+    obj = JS_NewModuleValue(ctx, m);
     if (bc_get_leb128_int(s, &m->req_module_entries_count))
         goto fail;
     if (m->req_module_entries_count != 0) {
@@ -35346,6 +35870,10 @@ static JSValue JS_ReadModule(BCReaderState *s)
         }
     }
 
+    if (bc_get_u8(s, &v8))
+        goto fail;
+    m->has_tla = (v8 != 0);
+
     m->func_obj = JS_ReadObjectRec(s);
     if (JS_IsException(m->func_obj))
         goto fail;
@@ -46270,12 +46798,6 @@ static const JSCFunctionListEntry js_generator_proto_funcs[] = {
 
 /* Promise */
 
-typedef enum JSPromiseStateEnum {
-    JS_PROMISE_PENDING,
-    JS_PROMISE_FULFILLED,
-    JS_PROMISE_REJECTED,
-} JSPromiseStateEnum;
-
 typedef struct JSPromiseData {
     JSPromiseStateEnum promise_state;
     /* 0=fulfill, 1=reject, list of JSPromiseReactionData.link */
@@ -46300,6 +46822,22 @@ typedef struct JSPromiseReactionData {
     JSValue handler;
 } JSPromiseReactionData;
 
+JSPromiseStateEnum JS_PromiseState(JSContext *ctx, JSValue promise)
+{
+    JSPromiseData *s = JS_GetOpaque(promise, JS_CLASS_PROMISE);
+    if (!s)
+        return -1;
+    return s->promise_state;
+}
+
+JSValue JS_PromiseResult(JSContext *ctx, JSValue promise)
+{
+    JSPromiseData *s = JS_GetOpaque(promise, JS_CLASS_PROMISE);
+    if (!s)
+        return JS_UNDEFINED;
+    return JS_DupValue(ctx, s->promise_result);
+}
+
 static int js_create_resolving_functions(JSContext *ctx, JSValue *args,
                                          JSValueConst promise);