[gjs/wip/gcampax/70-arg-cache: 3/5] function: don't root the out argument locations

[Philip Chimento <pchimento src gnome org>]

commit 55305508ed9726f7d5a5d594433ef3537cdf52f1
Author: Giovanni Campagna <gcampagna src gnome org>
Date:   Sun Apr 21 20:21:40 2013 +0200

    function: don't root the out argument locations
    
    Instead, build the array object eagerly if it's know that it will
    be needed, and rely on the stack scanner to find the array itself.

 gi/function.cpp | 46 +++++++++++++---------------------------------
 1 file changed, 13 insertions(+), 33 deletions(-)
---
diff --git a/gi/function.cpp b/gi/function.cpp
index 5722850..585bed7 100644
--- a/gi/function.cpp
+++ b/gi/function.cpp
@@ -723,7 +723,6 @@ gjs_invoke_c_function(JSContext                             *context,
     bool is_method;
     bool is_object_method = FALSE;
     GITypeTag return_tag;
-    JS::AutoValueVector return_values(context);
     GSList *iter;
 
     /* Because we can't free a closure while we're in it, we defer
@@ -887,11 +886,8 @@ gjs_invoke_c_function(JSContext                             *context,
                                               &state.out_cvalues[-1]);
     }
 
-    if (function->js_out_argc > 0) {
-        for (size_t i = 0; i < function->js_out_argc; i++)
-            if (!return_values.append(JS::UndefinedValue()))
-                g_error("Unable to append to vector");
-    }
+    if (function->js_out_argc > 1)
+        js_rval->setObject(*JS_NewArrayObject(context, 0));
 
     /* Process out arguments and return values. This loop is skipped if we fail
      * the type conversion above, or if did_throw_gerror is true. */
@@ -901,14 +897,22 @@ gjs_invoke_c_function(JSContext                             *context,
         GjsArgumentCache *cache = &function->arguments[gi_arg_pos];
         GIArgument *out_value = &state.out_cvalues[gi_arg_pos];
 
-        if (!cache->marshal_out(context, cache, &state, out_value,
-                                return_values[js_arg_pos])) {
+        JS::RootedValue value(context);
+        if (!cache->marshal_out(context, cache, &state, out_value, &value)) {
             failed = true;
             break;
         }
 
-        if (!gjs_arg_cache_is_skip_out(cache))
+        if (!gjs_arg_cache_is_skip_out(cache)) {
+            if (function->js_out_argc == 1) {
+                js_rval->set(value);
+            } else {
+                JS::RootedObject js_rval_array(context, &js_rval->toObject());
+                JS_SetElement(context, js_rval_array, js_arg_pos, value);
+            }
+
             js_arg_pos++;
+        }
     }
 
     g_assert(failed || did_throw_gerror || js_arg_pos == uint8_t(function->js_out_argc));
@@ -940,30 +944,6 @@ release:
 
     g_assert_cmpuint(ffi_arg_pos, ==, processed_c_args + 1);
 
-    if (function->js_out_argc > 0 && (!failed && !did_throw_gerror)) {
-        /* if we have 1 return value or out arg, return that item
-         * on its own, otherwise return a JavaScript array with
-         * [return value, out arg 1, out arg 2, ...]
-         */
-        if (js_rval) {
-            if (function->js_out_argc == 1) {
-                js_rval.ref().set(return_values[0]);
-            } else {
-                JSObject *array;
-                array = JS_NewArrayObject(context, return_values);
-                if (array == NULL) {
-                    failed = true;
-                } else {
-                    js_rval.ref().setObject(*array);
-                }
-            }
-        }
-
-        if (r_value) {
-            *r_value = state.out_cvalues[-1];
-        }
-    }
-
     if (!failed && did_throw_gerror) {
         gjs_throw_g_error(context, local_error);
         return false;