Improve optimization of operations on indexables by using more inferred type information and by dis…

sdk/lib/_internal/compiler/implementation/ssa/optimize.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;
 
 abstract class OptimizationPhase {
   String get name;
   void visitGraph(HGraph graph);
 }
@@ skipping 964 matching lines @@
     if (boundsChecked.contains(node)) return;
     HInstruction index = node.index;
     if (!node.index.isInteger()) {
       index = insertIntegerCheck(node, index);
     }
     index = insertBoundsCheck(node, node.receiver, index);
     node.changeUse(node.index, index);
   }
 
   void visitIndexAssign(HIndexAssign node) {
-    if (!node.receiver.isMutableArray()) return;
     if (boundsChecked.contains(node)) return;
     HInstruction index = node.index;
     if (!node.index.isInteger()) {
       index = insertIntegerCheck(node, index);
     }
     index = insertBoundsCheck(node, node.receiver, index);
     node.changeUse(node.index, index);
   }
 
   void visitInvokeDynamicMethod(HInvokeDynamicMethod node) {
@@ skipping 715 matching lines @@
     HBasicBlock block = user.block;
     block.addAfter(user, interceptor);
     block.rewrite(user, interceptor);
     block.remove(user);
 
     // The interceptor will be removed in the dead code elimination
     // phase. Note that removing it here would not work because of how
     // the [visitBasicBlock] is implemented.
   }
 }