Default value constants are created only call uses them

pkg/compiler/lib/src/ssa/builder_kernel.dart

Index: pkg/compiler/lib/src/ssa/builder_kernel.dart
diff --git a/pkg/compiler/lib/src/ssa/builder_kernel.dart b/pkg/compiler/lib/src/ssa/builder_kernel.dart
index 597d6fa9a55ef78c336b36dad2bf14199f7a9a31..60fda9d01b2ad6d19493b83e39f353a42f8f884e 100644
--- a/pkg/compiler/lib/src/ssa/builder_kernel.dart
+++ b/pkg/compiler/lib/src/ssa/builder_kernel.dart
@@ -32,7 +32,7 @@ import '../tree/nodes.dart' show Node;
 import '../types/masks.dart';
 import '../universe/selector.dart';
 import '../universe/side_effects.dart' show SideEffects;
-import '../universe/use.dart' show DynamicUse;
+import '../universe/use.dart' show ConstantUse, DynamicUse;
 import '../universe/world_builder.dart' show CodegenWorldBuilder;
 import '../world.dart';
 import 'graph_builder.dart';
@@ -145,6 +145,7 @@ class KernelSsaGraphBuilder extends ir.Visitor
         }
         buildField(target);
       } else if (target is ir.Constructor) {
+        _targetFunction = (target as ir.Constructor).function;
         if (targetElement is ConstructorBodyEntity) {
           buildConstructorBody(target);
         } else {
@@ -161,10 +162,43 @@ class KernelSsaGraphBuilder extends ir.Visitor
             '$target for $targetElement';
       }
       assert(graph.isValid());
+      if (_targetFunction != null) {
+        _ensureDefaultArgumentValues(_targetFunction);
+      }
       return graph;
     });
   }
 
+  void _ensureDefaultArgumentValues(ir.FunctionNode function) {
+    // Register all [function]'s default argument values.
+    //
+    // Default values might be (or contain) functions that are not referenced
+    // from anywhere else so we need to ensure these are enqueued.  Stubs and
+    // `Function.apply` data are created after the codegen queue is closed, so
+    // we force these functions into the queue by registering the constants as
+    // used in advance. See language/cyclic_default_values_test.dart for an
+    // example.
+    //
+    // TODO(sra): We could be more precise if stubs and `Function.apply` data
+    // were generated by the codegen enqueuer. In practice even in huge programs
+    // there are only very small number of constants created here that are not
+    // actually used.
+    void registerDefaultValue(ir.VariableDeclaration node) {
+      ConstantValue constantValue =
+          _elementMap.getConstantValue(node.initializer, implicitNull: true);
+      assert(
+          constantValue != null,
+          failedAt(_elementMap.getMethod(function.parent),
+              'No constant computed for $node'));
+      registry?.registerConstantUse(new ConstantUse.init(constantValue));
+    }
+
+    function.positionalParameters
+        .skip(function.requiredParameterCount)
+        .forEach(registerDefaultValue);
+    function.namedParameters.forEach(registerDefaultValue);
+  }
+
   @override
   ConstantValue getFieldInitialConstantValue(FieldEntity field) {
     assert(field == targetElement);