Build new IR for functions returning a constant

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

Index: sdk/lib/_internal/compiler/implementation/inferrer/ir_type_inferrer.dart
diff --git a/sdk/lib/_internal/compiler/implementation/inferrer/ir_type_inferrer.dart b/sdk/lib/_internal/compiler/implementation/inferrer/ir_type_inferrer.dart
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+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library ir_type_inferrer;
+
+import '../ir/ir_nodes.dart';
+import 'inferrer_visitor.dart' show
+    TypeSystem;
+import 'simple_types_inferrer.dart' show
+    InferrerEngine;
+import '../elements/elements.dart' show
+    Element;
+import '../dart2jslib.dart' show
+    Compiler, Constant, ConstantSystem;
+
+class IrTypeInferrerVisitor<T> extends IrNodesVisitor<T> {
+  final Compiler compiler;
+  final Element analyzedElement;
+  final TypeSystem<T> types;
+  final InferrerEngine<T, TypeSystem<T>> inferrer;
+
+  IrTypeInferrerVisitor(
+      this.compiler, this.analyzedElement, this.types, this.inferrer);
+
+  T typeOfConstant(Constant constant) {
+    if (constant.isBool()) return types.boolType;
+    if (constant.isNum()) {
+      ConstantSystem constantSystem = compiler.backend.constantSystem;
+      // The JavaScript backend may turn this literal into a double at runtime.
+      if (constantSystem.isDouble(constant)) return types.doubleType;
+      return types.intType;
+    }
+    if (constant.isString()) return types.stringType;
+    if (constant.isNull()) return types.nullType;
+    compiler.internalError("Unexpected constant: $constant");
+  }
+
+  T visitIrConstant(IrConstant node) {
+    return typeOfConstant(node.value);
+  }
+
+  T visitIrFunction(IrFunction node) {
+    // TODO implement this method
+  }
+
+  T visitIrReturn(IrReturn node) {
+    inferrer.addReturnTypeFor(analyzedElement, null, node.value.accept(this));
+  }
+}