Inline create parameter mirror list functionality.

runtime/lib/mirrors.cc

Index: runtime/lib/mirrors.cc
diff --git a/runtime/lib/mirrors.cc b/runtime/lib/mirrors.cc
index 790705a11158304af0057734caf38f472c3b9573..b0613bd40ddaead79ebce0d503193ef2d5b0257c 100644
--- a/runtime/lib/mirrors.cc
+++ b/runtime/lib/mirrors.cc
@@ -235,47 +235,39 @@ static Dart_Handle UnwrapMirror(Dart_Handle mirror) {
 static Dart_Handle CreateLazyMirror(Dart_Handle target);
 
 
-static Dart_Handle CreateParameterMirrorList(Dart_Handle func) {
+static RawInstance* CreateParameterMirrorList(const Function& func) {
+  const intptr_t param_cnt = func.num_fixed_parameters() -

[Michael Lippautz (Google), 2013/07/23 18:41:46]

num_fixed_parameters() includes the implicit ones (which we don't want).

+                             func.NumImplicitParameters() +
+                             func.NumOptionalParameters();
+  const Array& results = Array::Handle(Array::New(param_cnt));
+  const Array& args = Array::Handle(Array::New(3));
+  const MirrorReference& reflectee = MirrorReference::Handle(
+      MirrorReference::New(func));
+  Smi& pos = Smi::Handle();
+  Instance& param = Instance::Handle();
+  for (intptr_t i = 0; i < param_cnt; ++i) {
+    pos ^= Smi::New(i);
+    args.SetAt(0, reflectee);

[siva, 2013/07/23 21:44:58]

This line can be hoisted out of the loop.

[Michael Lippautz (Google), 2013/07/23 23:18:13]

Done.

+    args.SetAt(1, pos);
+    args.SetAt(2, (i >= func.num_fixed_parameters()) ?
+        Bool::True() : Bool::False());
+    param ^= CreateMirror(Symbols::_LocalParameterMirrorImpl(), args);

[Michael Lippautz (Google), 2013/07/23 18:41:46]

This looks up the class each time it is invoked (library is cached). For now we
consider this as acceptable.

+    results.SetAt(i, param);
+  }
+  results.MakeImmutable();
+  return results.raw();
+}
+
+
+static Dart_Handle CreateParameterMirrorListUsingApi(Dart_Handle func) {
   ASSERT(Dart_IsFunction(func));
-  int64_t fixed_param_count;
-  int64_t opt_param_count;
-  Dart_Handle result = Dart_FunctionParameterCounts(func,
-                                                    &fixed_param_count,
-                                                    &opt_param_count);
-  if (Dart_IsError(result)) {
-    return result;
-  }
-
-  int64_t param_count = fixed_param_count + opt_param_count;
-  Dart_Handle parameter_list = Dart_NewList(param_count);
-  if (Dart_IsError(parameter_list)) {
-    return result;
-  }
-
-  Dart_Handle param_cls_name = NewString("_LocalParameterMirrorImpl");
-  Dart_Handle param_type = Dart_GetType(MirrorLib(), param_cls_name, 0, NULL);
-  if (Dart_IsError(param_type)) {
-    return param_type;
-  }
-
-  Dart_Handle reflectee = CreateMirrorReference(func);
-  for (int64_t i = 0; i < param_count; i++) {
-    Dart_Handle args[] = {
-      reflectee,
-      Dart_NewInteger(i),
-      (i >= fixed_param_count) ? Api::True() : Api::False(),
-    };
-    Dart_Handle param =
-        Dart_New(param_type, Dart_Null(), ARRAY_SIZE(args), args);
-    if (Dart_IsError(param)) {
-      return param;
-    }
-    result = Dart_ListSetAt(parameter_list, i, param);
-    if (Dart_IsError(result)) {
-      return result;
-    }
-  }
-  return parameter_list;
+  Isolate* isolate = Isolate::Current();
+  Instance& retvalue = Instance::Handle();
+  Dart_EnterScope();

[Michael Lippautz (Google), 2013/07/23 18:41:46]

Right now the parameter list is created eagerly when a method mirror is created
(changing soon). Since method mirrors might be populated from creating a mirror
system, we avoid producing too much garbage by entering a temporary scope.

+  const Function& func_obj = Api::UnwrapFunctionHandle(isolate, func);
+  retvalue ^= CreateParameterMirrorList(func_obj);
+  Dart_ExitScope();

[siva, 2013/07/23 21:44:58]

why do you need a Dart_EnterScope() / Dart_ExitScope() here?

[Michael Lippautz (Google), 2013/07/23 23:18:13]

As discussed offline, we rather use a HANDLESCOPE in the native method isntead.

+  return Api::NewHandle(isolate, retvalue.raw());
 }
 
 
@@ -304,7 +296,7 @@ static Dart_Handle CreateLazyMirror(Dart_Handle target) {
 
       Dart_Handle args[] = {
         CreateLazyMirror(return_type),
-        CreateParameterMirrorList(sig),
+        CreateParameterMirrorListUsingApi(sig),
       };
       return Dart_New(type, Dart_Null(), ARRAY_SIZE(args), args);
     } else {
@@ -583,7 +575,7 @@ static Dart_Handle CreateMethodMirrorUsingApi(Dart_Handle func,
   Dart_Handle args[] = {
     CreateMirrorReference(func),
     owner_mirror,
-    CreateParameterMirrorList(func),
+    CreateParameterMirrorListUsingApi(func),
     func_obj.is_static() ? Api::True() : Api::False(),
     func_obj.is_abstract() ? Api::True() : Api::False(),
     func_obj.IsGetterFunction() ? Api::True() : Api::False(),