Compute frontend/backend specific constants.

sdk/lib/_internal/compiler/implementation/compiler.dart

Index: sdk/lib/_internal/compiler/implementation/compiler.dart
diff --git a/sdk/lib/_internal/compiler/implementation/compiler.dart b/sdk/lib/_internal/compiler/implementation/compiler.dart
index c756277a8f02eea7e5c69bfaf008adcc7d05496b..ac1d6053d7dfeb1a79424b2d6ad36a83f087ed88 100644
--- a/sdk/lib/_internal/compiler/implementation/compiler.dart
+++ b/sdk/lib/_internal/compiler/implementation/compiler.dart
@@ -74,11 +74,14 @@ class DeferredTask {
 
 abstract class Backend {
   final Compiler compiler;
-  final ConstantSystem constantSystem;
 
-  Backend(this.compiler,
-          [ConstantSystem constantSystem = DART_CONSTANT_SYSTEM])
-      : this.constantSystem = constantSystem;
+  Backend(this.compiler);

[floitsch, 2014/04/02 16:50:02]

Add comments what and when they are used.
Are they always doing backend-constant handling?
Do they also do Dart-handling?
May they ever expose non-Dart handling?

[Johnni Winther, 2014/04/07 11:42:27]

Done.

+
+  ConstantSystem get constantSystem;
+
+  BackendConstantHandler get constantHandler;
+
+  ConstantCompiler get constantCompiler;
 
   // Given a [FunctionElement], return a buffer with the code generated for it
   // or null if no code was generated.
@@ -669,12 +672,12 @@ abstract class Compiler implements DiagnosticListener {
       dietParser = new DietParserTask(this),
       parser = new ParserTask(this),
       patchParser = new PatchParserTask(this),
-      resolver = new ResolverTask(this),
+      resolver = new ResolverTask(this, backend.constantCompiler),
       closureToClassMapper = new closureMapping.ClosureTask(this, closureNamer),
       checker = new TypeCheckerTask(this),
       irBuilder = new IrBuilderTask(this),
       typesTask = new ti.TypesTask(this),
-      constantHandler = new ConstantHandler(this, backend.constantSystem),
+      constantHandler = backend.constantCompiler,

[floitsch, 2014/04/02 16:50:02]

It feels wrong (when reading) to assign a compiler to a handler. Especially when
the backend also has a constantHandler.

[Johnni Winther, 2014/04/07 11:42:27]

Done.

       deferredLoadTask = new DeferredLoadTask(this),
       mirrorUsageAnalyzerTask = new MirrorUsageAnalyzerTask(this),
       enqueuer = new EnqueueTask(this),
@@ -933,8 +936,8 @@ abstract class Compiler implements DiagnosticListener {
 
     dynamicClass.ensureResolved(this);
 
-    proxyConstant = constantHandler.compileVariable(
-        coreLibrary.find('proxy'), isConst: true);
+    proxyConstant =
+        resolver.constantCompiler.compileConstant(coreLibrary.find('proxy'));

[floitsch, 2014/04/02 16:50:02]

Why go through the resolver?

[Johnni Winther, 2014/04/07 11:42:27]

We need the frontend interpretation. Putting the constant compiler on the
resolver instead of on the Compiler itself is deliberate, to show that
compilation of compile-time constants is part of the resolution phase.

   }
 
   Element _unnamedListConstructor;