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 077728977bfaf55e1091c1fb3140c7e4f0d21939..63100c9a549f3a501caad2eae838d8d8506fe74c 100644
--- a/lib/compiler/implementation/compiler.dart
+++ b/lib/compiler/implementation/compiler.dart
@@ -111,6 +111,8 @@ class Compiler implements DiagnosticListener {
       return f();
     } catch (CompilerCancelledException ex) {
       throw;
+    } catch (Pass2BailoutException ex) {
+      throw;
     } catch (var ex) {
       unhandledExceptionOnElement(element);
       throw;
@@ -130,6 +132,7 @@ 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');
@@ -381,6 +384,25 @@ class Compiler implements DiagnosticListener {
       withCurrentElement(work.element, () => work.run(this, world));
     }
     world.queueIsClosed = true;
+    log("Recompilation candidates queue length: "
+        "${world.recompilationCandidates.length}");
+    pass = 2;
+    while (!world.recompilationCandidates.isEmpty()) {
+      WorkItem work = world.recompilationCandidates.next();
+      var oldCode = world.universe.generatedCode[work.element];
+      world.universe.generatedCode.remove(work.element);
+      try {
+        withCurrentElement(work.element, () => work.run(this, world));
+      } catch (Pass2BailoutException ex) {
+        world.universe.generatedCode[work.element] = oldCode;
+      }
+      var newCode = world.universe.generatedCode[work.element];
+      if (newCode != oldCode) {
+        log("PASS 2 OPTIMIZATION:");
+        log("Before: $oldCode");
+        log("After: $newCode");
+      }
+    }
     assert(world.checkNoEnqueuedInvokedInstanceMethods());
     world.registerFieldClosureInvocations();
   }
@@ -463,6 +485,7 @@ class Compiler implements DiagnosticListener {
       if (message.message.kind === MessageKind.METHOD_NOT_FOUND) return;
     }
     SourceSpan span = spanFromNode(node);
+
     reportDiagnostic(span, "${magenta('warning:')} $message", false);
   }
 
@@ -560,6 +583,15 @@ class CompilerCancelledException implements Exception {
   }
 }
 
+class Pass2BailoutException implements Exception {
+  final String reason;
+  Pass2BailoutException(this.reason);
+
+  String toString() {
+    return 'Pass 2 not supported: $reason';
+  }
+}
+
 class Tracer {
   final bool enabled = false;