Improve performance of addAll for internallt known lists.

runtime/lib/growable_array.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.
 
 class _GrowableList<T> extends ListBase<T> {
 
   void insert(int index, T element) {
     if ((index < 0) || (index > length)) {
       throw new RangeError.range(index, 0, length);
     }
@@ skipping 134 matching lines @@
     var len = length;
     if (len == _capacity) {
       _grow(len * 2);
     }
     _setLength(len + 1);
     this[len] = value;
   }
 
   void addAll(Iterable<T> iterable) {
     var len = length;
-    if (iterable is EfficientLength) {
+    final cid = ClassID.getID(iterable);
+    final isList =

[Cutch, 2015/01/26 20:56:38]

maybe rename isBuiltinList, isVMList?

[srdjan, 2015/01/26 21:34:09]

isVMList.

+        (cid == ClassID.cidArray) ||
+        (cid == ClassID.cidGrowableObjectArray) ||
+        (cid == ClassID.cidImmutableArray);
+    if (isList || iterable is EfficientLength) {
       var cap = _capacity;
       // Pregrow if we know iterable.length.
       var iterLen = iterable.length;
       var newLen = len + iterLen;
       if (newLen > cap) {
         do {
           cap *= 2;
         } while (newLen > cap);
         _grow(cap);
       }
+      if (isList) {

[Cutch, 2015/01/26 20:56:38]

Should this block (171-180) be moved down to 182?

[srdjan, 2015/01/26 21:34:09]

This code can be executed only if isVMList is true (if (isVMList || iterable is
EfficientLength). If I move it out I would need to recompute 'newLen' and
'iterLen',  and would not change the behavior. 

+        if (identical(iterable, this)) {
+          throw new ConcurrentModificationError(this);
+        }
+        this._setLength(newLen);
+        for (int i = 0; i < iterLen; i++) {
+          this[len++] = iterable[i];
+        }
+        return;
+      }
     }
     Iterator it = iterable.iterator;
     if (!it.moveNext()) return;
     do {
       while (len < _capacity) {
         int newLen = len + 1;
         this._setLength(newLen);
         this[len] = it.current;
         if (!it.moveNext()) return;
         if (this.length != newLen) throw new ConcurrentModificationError(this);
@@ skipping 145 matching lines @@
       result._setLength(length);
       return result;
     }
     return growable ? <T>[] : new List<T>(0);
   }
 
   Set<T> toSet() {
     return new Set<T>.from(this);
   }
 }