Improve tracking of the type of fields after object construction

lib/compiler/implementation/ssa/codegen.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 SsaCodeGeneratorTask extends CompilerTask {
   final JavaScriptBackend backend;
   SsaCodeGeneratorTask(JavaScriptBackend backend)
       : this.backend = backend,
         super(backend.compiler);
   String get name() => 'SSA code generator';
@@ skipping 1705 matching lines @@
     buffer.add('.');
     buffer.add(name);
     beginExpression(JSPrecedence.MEMBER_PRECEDENCE);
     Type type = node.receiver.propagatedType.computeType(compiler);
     if (type != null) {
       world.registerFieldGetter(node.element.name, type);
     }
   }
 
   visitFieldSet(HFieldSet node) {
+    if (work.element.isGenerativeConstructorBody() &&
+        node.element.enclosingElement.isClass() &&
+        node.value.hasGuaranteedType() &&
+        node.block.dominates(currentGraph.exit)) {

[ngeoffray, 2012/07/09 21:17:41]

We should probably have a helper method for this instead. Something like
HBasicBlock.isAlwaysExecuted.

+      backend.updateFieldConstructorSetters(node.element,
+                                            node.value.guaranteedType);
+    }
     String name = compiler.namer.getName(node.element);
     beginExpression(JSPrecedence.ASSIGNMENT_PRECEDENCE);
     use(node.receiver, JSPrecedence.MEMBER_PRECEDENCE);
     buffer.add('.');
     buffer.add(name);
     Type type = node.receiver.propagatedType.computeType(compiler);
     if (type != null) {
       world.registerFieldSetter(node.element.name, type);
       backend.updateFieldIntegerSetters(node.element,
                                         node.value.isInteger());
@@ skipping 1179 matching lines @@
       startBailoutSwitch();
     }
   }
 
   void endLabeledBlock(HLabeledBlockInformation labeledBlockInfo) {
     if (labeledBlockInfo.body.start.hasGuards()) {
       endBailoutSwitch();
     }
   }
 }