Retain fewer names for reflection.

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

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of js_backend;
 
 class JavaScriptItemCompilationContext extends ItemCompilationContext {
   final Set<HInstruction> boundsChecked;
 
   JavaScriptItemCompilationContext()
@@ skipping 1377 matching lines @@
       metadataStaticUse.clear();
       for (Element e in metadataGetOfStaticFunction) {
         registerMetadataGetOfStaticFunction(e);
       }
       metadataGetOfStaticFunction.clear();
     }
   }
 
   /// 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;
 
   bool retainMetadataOf(Element element) {
     if (mustRetainMetadata) {
       // TODO(ahe): This is a little hacky, but I'll have to rewrite this when
       // implementing @MirrorsUsed anyways.
       compiler.constantHandler.compiledConstants.addAll(
           compiler.metadataHandler.compiledConstants);
       compiler.metadataHandler.compiledConstants.clear();
@@ skipping 49 matching lines @@
           targetsUsed.add(field.getter);
           targetsUsed.add(field.setter);
         } else {
           targetsUsed.add(target);
         }
       }
     }
     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;
   }
 }
 
 /// Records that [type] is used by [user.element].
 class Dependency {
   final DartType type;
   final TreeElements user;
 
   const Dependency(this.type, this.user);
 }