Various caches for incremental compilation.

dart/sdk/lib/_internal/compiler/implementation/enqueue.dart

Index: dart/sdk/lib/_internal/compiler/implementation/enqueue.dart
diff --git a/dart/sdk/lib/_internal/compiler/implementation/enqueue.dart b/dart/sdk/lib/_internal/compiler/implementation/enqueue.dart
index 3e9921a03a4f18b13a86cacabcb572c90a119463..e0ac24b688d5645496a2d4a2cb82062c0aa27051 100644
--- a/dart/sdk/lib/_internal/compiler/implementation/enqueue.dart
+++ b/dart/sdk/lib/_internal/compiler/implementation/enqueue.dart
@@ -721,6 +721,8 @@ class CodegenEnqueuer extends Enqueuer {
   final Map<Element, js.Expression> generatedCode =
       new Map<Element, js.Expression>();
 
+  final Set<Element> newlyEnqueuedElements = new HashSet<Element>.identity();

[Johnni Winther, 2014/06/19 09:22:32]

Element equality is object identity so why do you need HashSet.identity ? 

[ahe, 2014/06/19 09:36:19]

Good point. I'll investigate if it matters. I doubt it will for elements.

[ahe, 2014/06/19 13:50:10]

I'm not sure I have specific evidence for this particular place, but in other
places, identity sets and maps had superior performance.

This is now encapsulated in a strategy.

+
   CodegenEnqueuer(Compiler compiler,
                   ItemCompilationContext itemCompilationContextCreator())
       : super('codegen enqueuer', compiler, itemCompilationContextCreator),
@@ -730,6 +732,9 @@ class CodegenEnqueuer extends Enqueuer {
       member.isAbstract || generatedCode.containsKey(member);
 
   void internalAddToWorkList(Element element) {
+    if (compiler.hasIncrementalSupport) {
+      newlyEnqueuedElements.add(element);
+    }
     // Don't generate code for foreign elements.
     if (element.isForeign(compiler)) return;