Clean up deferred checks in Kernel.

pkg/compiler/lib/src/kernel/kernel_visitor.dart

Index: pkg/compiler/lib/src/kernel/kernel_visitor.dart
diff --git a/pkg/compiler/lib/src/kernel/kernel_visitor.dart b/pkg/compiler/lib/src/kernel/kernel_visitor.dart
index 151247aad0e40209d19d1c52a5e4135da0755254..e7e642e5965e15f86fed9379b15c209d274932d9 100644
--- a/pkg/compiler/lib/src/kernel/kernel_visitor.dart
+++ b/pkg/compiler/lib/src/kernel/kernel_visitor.dart
@@ -1224,9 +1224,9 @@ class KernelVisitor extends Object
   }
 
   @override
-  ir.TypeLiteral visitClassTypeLiteralGet(
+  ir.Expression visitClassTypeLiteralGet(
       Send node, ConstantExpression constant, _) {
-    return buildTypeLiteral(constant);
+    return _addCheckLibraryLoadedIfNeeded(buildTypeLiteral(constant));
   }
 
   @override
@@ -2014,14 +2014,8 @@ class KernelVisitor extends Object
   }
 
   ir.Expression buildStaticGet(Element element) {
-    var expression = buildStaticAccessor(element).buildSimpleRead();
-    if (_deferredLibrary != null) {
-      ir.Let let = new ir.Let(
-          makeOrReuseVariable(new ir.CheckLibraryIsLoaded(_deferredLibrary)),
-          expression);
-      return let;
-    }
-    return expression;
+    return _addCheckLibraryLoadedIfNeeded(
+        buildStaticAccessor(element).buildSimpleRead());
   }
 
   @override
@@ -2714,10 +2708,23 @@ class KernelVisitor extends Object
     return buildIrFunction(ir.ProcedureKind.Setter, setter, body);
   }
 
+  ir.Expression _addCheckLibraryLoadedIfNeeded(ir.Expression inputExpression) {
+    if (_deferredLibrary != null) {
+      ir.Let let = new ir.Let(
+          makeOrReuseVariable(new ir.CheckLibraryIsLoaded(_deferredLibrary)),
+          inputExpression);
+      // Only need to add this check once per statement, regardless of the
+      // number of expressions that access a deferred member.

[sra1, 2017/02/15 23:55:31]

consider:

  prefix1.foo(prefix2.a, prefix3.b)

does this check the prefixes in the right order?

[Emily Fortuna, 2017/02/16 02:21:56]

yes.

+      _deferredLibrary = null;
+      return let;
+    }
+    return inputExpression;
+  }
+
   @override
-  ir.TypeLiteral visitTypeVariableTypeLiteralGet(
+  ir.Expression visitTypeVariableTypeLiteralGet(
       Send node, TypeVariableElement element, _) {
-    return buildTypeVariable(element);
+    return _addCheckLibraryLoadedIfNeeded(buildTypeVariable(element));
   }
 
   @override
@@ -2746,9 +2753,9 @@ class KernelVisitor extends Object
   }
 
   @override
-  ir.TypeLiteral visitTypedefTypeLiteralGet(
+  ir.Expression visitTypedefTypeLiteralGet(
       Send node, ConstantExpression constant, _) {
-    return buildTypeLiteral(constant);
+    return _addCheckLibraryLoadedIfNeeded(buildTypeLiteral(constant));
   }
 
   @override