Indexer one-shot fast path adjustment

pkg/compiler/lib/src/js_emitter/interceptor_stub_generator.dart

 // Copyright (c) 2014, 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 dart2js.js_emitter;
 
 class InterceptorStubGenerator {
   final Compiler compiler;
   final Namer namer;
   final JavaScriptBackend backend;
@@ skipping 199 matching lines @@
       } else {
         assert(name == '~');
         return js.statement('''
           if (typeof receiver == "number" && Math.floor(receiver) == receiver)
             return (~receiver) >>> 0;
           ''');
       }
     } else if (selector.isIndex || selector.isIndexSet) {
       // For an index operation, this code generates:
       //
-      //    if (receiver.constructor == Array || typeof receiver == "string") {
-      //      if (a0 >>> 0 === a0 && a0 < receiver.length) {
-      //        return receiver[a0];
+      //    if (typeof a0 === "number") {
+      //      if (receiver.constructor == Array ||
+      //          typeof receiver == "string") {
+      //        if (a0 >>> 0 === a0 && a0 < receiver.length) {
+      //          return receiver[a0];
+      //        }
       //      }
       //    }
       //
       // For an index set operation, this code generates:
       //
-      //    if (receiver.constructor == Array && !receiver.immutable$list) {
-      //      if (a0 >>> 0 === a0 && a0 < receiver.length) {
-      //        return receiver[a0] = a1;
+      //    if (typeof a0 === "number") {
+      //      if (receiver.constructor == Array && !receiver.immutable$list) {
+      //        if (a0 >>> 0 === a0 && a0 < receiver.length) {
+      //          return receiver[a0] = a1;
+      //        }
       //      }
       //    }
       bool containsArray = classes.contains(helpers.jsArrayClass);
       bool containsString = classes.contains(helpers.jsStringClass);
       bool containsJsIndexable =
           helpers.jsIndexingBehaviorInterface.isResolved && classes.any((cls) {
         return compiler.world.isSubtypeOf(cls,
             helpers.jsIndexingBehaviorInterface);
       });
       // The index set operator requires a check on its set value in
@@ skipping 22 matching lines @@
 
         if (containsString) {
           typeCheck = orExp(typeCheck, js('typeof receiver == "string"'));
         }
 
         if (containsJsIndexable) {
           typeCheck = orExp(typeCheck, indexableCheck);
         }
 
         return js.statement('''
-          if (#)
-            if ((a0 >>> 0) === a0 && a0 < receiver.length)
-              return receiver[a0];
+          if (typeof a0 === "number")
+            if (#)
+              if ((a0 >>> 0) === a0 && a0 < receiver.length)
+                return receiver[a0];
           ''', typeCheck);
       } else {
         jsAst.Expression typeCheck;
         if (containsArray) {
           typeCheck = arrayCheck;
         }
 
         if (containsJsIndexable) {
           typeCheck = orExp(typeCheck, indexableCheck);
         }
 
         return js.statement(r'''
-          if (# && !receiver.immutable$list &&
-              (a0 >>> 0) === a0 && a0 < receiver.length)
-            return receiver[a0] = a1;
+          if (typeof a0 === "number")
+            if (# && !receiver.immutable$list &&
+                (a0 >>> 0) === a0 && a0 < receiver.length)
+              return receiver[a0] = a1;
           ''', typeCheck);
       }
     }
     return null;
   }
 
   jsAst.Expression generateOneShotInterceptor(jsAst.Name name) {
     Selector selector = backend.oneShotInterceptors[name];
     Set<ClassElement> classes =
         backend.getInterceptedClassesOn(selector.name);
@@ skipping 69 matching lines @@
 
           var map = new jsAst.ObjectInitializer(properties);
           elements.add(map);
         }
       }
     }
 
     return new jsAst.ArrayInitializer(elements);
   }
 }