Prototype re-compiling methods in dart2js

lib/compiler/implementation/compiler.dart

Index: lib/compiler/implementation/compiler.dart
diff --git a/lib/compiler/implementation/compiler.dart b/lib/compiler/implementation/compiler.dart
index b3f16992d4ebd9665157b472f113375c047ec38c..582d15d6b61e6372c04134fc1e7a6055371d5f74 100644
--- a/lib/compiler/implementation/compiler.dart
+++ b/lib/compiler/implementation/compiler.dart
@@ -9,6 +9,11 @@
  */
 final bool REPORT_EXCESS_RESOLUTION = false;
 
+/**
+ * If true, trace information on pass2 optimizations.
+ */
+final bool REPORT_PASS2_OPTIMIZATIONS = false;
+
 class WorkItem {
   final Element element;
   TreeElements resolutionTree;
@@ -157,6 +162,7 @@ class Compiler implements DiagnosticListener {
   Backend backend;
   ConstantHandler constantHandler;
   EnqueueTask enqueuer;
+  int pass = 1;
 
   static final SourceString MAIN = const SourceString('main');
   static final SourceString NO_SUCH_METHOD = const SourceString('noSuchMethod');
@@ -410,6 +416,9 @@ class Compiler implements DiagnosticListener {
 
     log('Compiling...');
     processQueue(enqueuer.codegen, main);
+    log("Recompiling ${enqueuer.codegen.recompilationCandidates.length} "
+        "methods...");
+    processRecompilationQueue(enqueuer.codegen);
     log('Compiled ${codegenWorld.generatedCode.length} methods.');
 
     backend.assembleProgram();
@@ -429,6 +438,22 @@ class Compiler implements DiagnosticListener {
     world.registerFieldClosureInvocations();
   }
 
+  processRecompilationQueue(Enqueuer world) {
+    pass = 2;
+    while (!world.recompilationCandidates.isEmpty()) {
+      WorkItem work = world.recompilationCandidates.next();
+      var oldCode = world.universe.generatedCode[work.element];
+      world.universe.generatedCode.remove(work.element);
+      withCurrentElement(work.element, () => work.run(this, world));
+      var newCode = world.universe.generatedCode[work.element];
+      if (REPORT_PASS2_OPTIMIZATIONS && newCode != oldCode) {
+        log("Pass 2 optimization:");
+        log("Before:\n$oldCode");
+        log("After:\n$newCode");
+      }
+    }
+  }
+
   /**
    * Perform various checks of the queues. This includes checking that
    * the queues are empty (nothing was added after we stopped
@@ -573,6 +598,7 @@ class Compiler implements DiagnosticListener {
       if (message.message.kind === MessageKind.METHOD_NOT_FOUND) return;
     }
     SourceSpan span = spanFromNode(node);
+
     reportDiagnostic(span, "${magenta('warning:')} $message", false);
   }