[dart2js] new-rti: Remove no-op evals.

rakudrama · commit-bot@chromium.org · commit 4cba23496acb · 2019-07-25T03:25:23.000Z
$T.eval$1("0") --> $T Change-Id: Ifb544563f963af5ac6005d6719aaeb45d4e393ec Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/110349 Commit-Queue: Stephen Adams <sra@google.com> Reviewed-by: Mayank Patke <fishythefish@google.com>
diff --git a/pkg/compiler/lib/src/js_model/type_recipe.dart b/pkg/compiler/lib/src/js_model/type_recipe.dart
@@ -79,6 +79,17 @@ abstract class TypeRecipe {
     // yield the same type, e.g. `List<X> @X` and `List<Y> @Y`.
     return false;
   }
+
+  /// Returns `true` if [recipe] evaluates in an environment with [structure] to
+  /// the environment.
+  static bool isIdentity(
+      TypeRecipe recipe, TypeEnvironmentStructure structure) {
+    if (structure is SingletonTypeEnvironmentStructure &&
+        recipe is TypeExpressionRecipe) {
+      if (structure.variable == recipe.type) return true;
+    }
+    return false;
+  }
 }
 
 /// A recipe that yields a reified type.
diff --git a/pkg/compiler/lib/src/ssa/optimize.dart b/pkg/compiler/lib/src/ssa/optimize.dart
@@ -18,6 +18,7 @@ import '../js_backend/field_analysis.dart'
 import '../js_backend/backend.dart' show CodegenInputs;
 import '../js_backend/native_data.dart' show NativeData;
 import '../js_backend/runtime_types_codegen.dart';
+import '../js_model/type_recipe.dart' show TypeRecipe;
 import '../native/behavior.dart';
 import '../options.dart';
 import '../universe/selector.dart' show Selector;
@@ -1846,6 +1847,14 @@ class SsaInstructionSimplifier extends HBaseVisitor
 
     return node;
   }
+
+  @override
+  HInstruction visitTypeEval(HTypeEval node) {
+    if (TypeRecipe.isIdentity(node.typeExpression, node.envStructure)) {
+      return node.inputs.single;
+    }
+    return node;
+  }
 }
 
 class SsaCheckInserter extends HBaseVisitor implements OptimizationPhase {
