Refactor types in ssa nodes.

lib/compiler/implementation/ssa/optimize.dart

 // Copyright (c) 2011, 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.
 
 interface OptimizationPhase {
   String get name();
   void visitGraph(HGraph graph);
 }
 
 class SsaOptimizerTask extends CompilerTask {
@@ skipping 323 matching lines @@
         return new HEquals(target, node.left, node.right);
       }
     }
 
     // All other cases are dealt with by the [visitInvokeBinary].
     return visitInvokeBinary(node);
   }
 
   HInstruction visitTypeGuard(HTypeGuard node) {
     HInstruction value = node.guarded;
-    HType combinedType = value.propagatedType.combine(node.guardedType);
+    // If the union of the types is still the guarded type than the incoming
+    // type was a subtype of the guarded type, and no check is required.
+    HType combinedType = value.propagatedType.union(node.guardedType);
     return (combinedType == value.propagatedType) ? value : node;
   }
 
   HInstruction visitIs(HIs node) {
     Type type = node.typeName;
     Element element = type.element;
     if (element.kind === ElementKind.TYPE_VARIABLE) {
       compiler.unimplemented("visitIs for type variables");
     }
 
@@ skipping 88 matching lines @@
     return check;
   }
 
   HIntegerCheck insertIntegerCheck(HInstruction node, HInstruction value) {
     HIntegerCheck check = new HIntegerCheck(value);
     node.block.addBefore(node, check);
     return check;
   }
 
   void visitIndex(HIndex node) {
-    if (!node.receiver.isStringOrArray()) return;
+    if (!node.receiver.isIndexablePrimitive()) return;
     HInstruction index = node.index;
     if (index is HBoundsCheck) return;
     if (!node.index.isInteger()) {
       index = insertIntegerCheck(node, index);
     }
     index = insertBoundsCheck(node, node.receiver, index);
     HIndex newInstruction = new HIndex(node.target, node.receiver, index);
     node.block.addBefore(node, newInstruction);
     node.block.rewrite(node, newInstruction);
     node.block.remove(node);
@@ skipping 399 matching lines @@
         }
       }
       if (!canBeMoved) continue;
 
       // This is safe because we are running after GVN.
       // TODO(ngeoffray): ensure GVN has been run.
       set_.add(current);
     }
   }
 }