Retain fewer names for reflection.

dart/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart

Index: dart/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
diff --git a/dart/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart b/dart/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
index b2175c53090a95f4f25ac2adb7729698fd04cc82..5084f28b8404e1f8e397d74fa90f1d0e75dd90a8 100644
--- a/dart/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
+++ b/dart/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
@@ -1395,17 +1395,21 @@ class JavaScriptBackend extends Backend {
 
   /// Called when [:const Symbol(name):] is seen.
   void registerConstSymbol(String name, TreeElements elements) {
+    symbolsUsed.add(name);
   }
 
   /// Called when [:new Symbol(...):] is seen.
   void registerNewSymbol(TreeElements elements) {
   }
 
-  bool retainGetter(Element element) => isTreeShakingDisabled;
+  bool retainGetter(Element element) => isNeededForReflection(element);

[Johnni Winther, 2013/08/07 10:47:34]

Rename these three to shouldRetainX, isXRetained or similar to indicate that
they are lookups and not registrations. And add documentation (if not already
present in Backend).

[ahe, 2013/08/07 14:03:17]

Done.

 
-  bool retainSetter(Element element) => isTreeShakingDisabled;
+  bool retainSetter(Element element) => isNeededForReflection(element);
 
-  bool retainName(SourceString name) => mustPreserveNames;
+  bool retainName(SourceString name) {
+    if (name == const SourceString('')) return false;
+    return symbolsUsed.contains(name.slowToString());
+  }
 
   bool get rememberLazies => isTreeShakingDisabled;
 
@@ -1475,12 +1479,20 @@ class JavaScriptBackend extends Backend {
     if (metaTargets != null) metaTargetsUsed.addAll(metaTargets);
   }
 
+  bool rememberNameOf(Element element) {

[Johnni Winther, 2013/08/07 10:47:34]

Ditto.

[ahe, 2013/08/07 14:03:17]

Done.

+    symbolsUsed.add(element.name.slowToString());
+    if (element.isConstructor()) {
+      symbolsUsed.add(element.getEnclosingClass().name.slowToString());
+    }
+    return true;
+  }
+
   bool isNeededForReflection(Element element) {
     // TODO(ahe): Implement this.
-    if (!metaTargetsUsed.isEmpty) return true;
+    if (!metaTargetsUsed.isEmpty) return rememberNameOf(element);
     if (!targetsUsed.isEmpty) {
       for (Element e = element; e != null; e = e.enclosingElement) {
-        if (targetsUsed.contains(e)) return true;
+        if (targetsUsed.contains(e)) return rememberNameOf(element);
       }
     }
     return false;