dart2js cps: Support --trust-primitives and --trust-type-annotations.

pkg/compiler/lib/src/cps_ir/insert_refinements.dart

Index: pkg/compiler/lib/src/cps_ir/insert_refinements.dart
diff --git a/pkg/compiler/lib/src/cps_ir/insert_refinements.dart b/pkg/compiler/lib/src/cps_ir/insert_refinements.dart
index 3b545c6968d1305afc378107e211f3efd92ee109..6c5ec7014720e6f5417b1d4887f9ed15070c3df8 100644
--- a/pkg/compiler/lib/src/cps_ir/insert_refinements.dart
+++ b/pkg/compiler/lib/src/cps_ir/insert_refinements.dart
@@ -9,6 +9,7 @@ import 'cps_ir_nodes.dart';
 import '../common/names.dart';
 import '../types/types.dart' show TypeMask;
 import 'type_mask_system.dart';
+import 'cps_fragment.dart';
 
 /// Inserts [Refinement] nodes in the IR to allow for sparse path-sensitive
 /// type analysis in the [TypePropagator] pass.
@@ -34,9 +35,13 @@ class InsertRefinements extends TrampolineRecursiveVisitor implements Pass {
 
   /// Updates references to refer to the refinement currently in scope.
   void processReference(Reference node) {
-    Refinement refined = refinementFor[node.definition];
-    if (refined != null) {
-      node.changeTo(refined);
+    Definition definition = node.definition;
+    if (definition is Primitive) {
+      Primitive prim = definition.effectiveDefinition;
+      Refinement refined = refinementFor[prim];
+      if (refined != null && refined != definition) {
+        node.changeTo(refined);
+      }
     }
   }
 
@@ -118,6 +123,34 @@ class InsertRefinements extends TrampolineRecursiveVisitor implements Pass {
     }
   }
 
+  void visitTypeCast(TypeCast node) {
+    Continuation cont = node.continuation.definition;
+    Primitive value = node.value.definition;
+
+    processReference(node.value);
+    node.typeArguments.forEach(processReference);
+
+    // Refine the type of the input.
+    sinkContinuationToUse(cont, node);
+    TypeMask type = types.subtypesOf(node.dartType).nullable();
+    Refinement refinement = new Refinement(value, type);
+    pushRefinement(cont, refinement);
+  }
+
+  void visitRefinement(Refinement node) {
+    // We found a pre-existing refinement node. These are generated by the
+    // IR builder to hold information from --trust-type-annotations.
+    // Update its input to use our own current refinement, then update the
+    // environment to use this refinement.
+    processReference(node.value);
+    Primitive value = node.value.definition.effectiveDefinition;
+    Primitive oldRefinement = refinementFor[value];
+    refinementFor[value] = node;
+    pushAction(() {
+      refinementFor[value] = oldRefinement;
+    });
+  }
+
   CallExpression getCallWithResult(Primitive prim) {
     if (prim is Parameter && prim.parent is Continuation) {
       Continuation cont = prim.parent;
@@ -205,9 +238,10 @@ class InsertRefinements extends TrampolineRecursiveVisitor implements Pass {
     for (Continuation cont in node.continuations) {
       if (cont.hasExactlyOneUse &&
           (cont.firstRef.parent is InvokeMethod ||
+           cont.firstRef.parent is TypeCast ||
            cont.firstRef.parent is Branch)) {
         // Do not push the continuation here.
-        // visitInvokeMethod and visitBranch will do that.
+        // visitInvokeMethod, visitBranch, and visitTypeCast will do that.
       } else {
         push(cont);
       }