Fix performance regression after adding inlining support for operators, [], and []=.

sdk/lib/_internal/compiler/implementation/ssa/builder.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 ssa;
 
 /**
  * A special element for the extra parameter taken by intercepted
  * methods. We need to override [Element.computeType] because our
  * optimizers may look at its declared type.
@@ skipping 3634 matching lines @@
         return type.isIndexable(compiler);
       } else if (selector.isIndexSet()) {
         DartType classType = element.getEnclosingClass().computeType(compiler);
         HType type = new HType.nonNullExact(classType, compiler);
         return type.isMutableIndexable(compiler);
       } else {
         return false;
       }
     }
 
-    bool isThisSend(Send send) {
-      if (send.isPrefix || send.isPostfix) return false;
-      Node receiver = send.receiver;
-      if (receiver == null) return true;
-      Identifier identifier = receiver.asIdentifier();
-      return identifier != null && identifier.isThis();
+    bool isOptimizableOperation(Send node, Selector selector, Element element) {
+      ClassElement cls = element.getEnclosingClass();
+      if (isOptimizableOperationOnIndexable(selector, element)) return true;
+      if (!backend.interceptedClasses.contains(cls)) return false;
+      if (selector.isOperator()) return true;
+      if (selector.isSetter()) return true;
+      if (selector.isIndex()) return true;
+      if (selector.isIndexSet()) return true;
+      if (element == backend.jsArrayAdd
+          || element == backend.jsArrayRemoveLast
+          || element == backend.jsStringSplit) {
+        return true;
+      }
+      return false;
     }
 
     Element element = compiler.world.locateSingleElement(selector);
     if (element != null
         // TODO(ngeoffray): Handle non-send nodes.
         && (node.asSend() != null)
         && !(element.isGetter() && selector.isCall())
         && !(element.isFunction() && selector.isGetter())
-        // This check is to ensure we don't regress compared to our
-        // previous limited inlining. We currently don't want to
-        // inline methods on intercepted classes because the
-        // optimizers apply their own optimizations on these methods.
-        && (!backend.interceptedClasses.contains(element.getEnclosingClass())
-            || isThisSend(node))
-        // Avoid inlining optimizable operations on indexables.
-        && !isOptimizableOperationOnIndexable(selector, element)) {
+        && !isOptimizableOperation(node, selector, element)) {
       Send send = node.asSend();
       Link<Node> nodes = send.isPropertyAccess ? null : send.arguments;
       if (tryInlineMethod(element, selector, nodes, arguments, node)) {
         return;
       }
     }
 
     HInstruction receiver = arguments[0];
     Set<ClassElement> interceptedClasses =
         backend.getInterceptedClassesOn(selector.name);
@@ skipping 1581 matching lines @@
           new HSubGraphBlockInformation(elseBranch.graph));
 
     HBasicBlock conditionStartBlock = conditionBranch.block;
     conditionStartBlock.setBlockFlow(info, joinBlock);
     SubGraph conditionGraph = conditionBranch.graph;
     HIf branch = conditionGraph.end.last;
     assert(branch is HIf);
     branch.blockInformation = conditionStartBlock.blockFlow;
   }
 }