Revert "Revert "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
new file mode 100644
index 0000000000000000000000000000000000000000..f76d0623b13a73f3bdb49ca672fa3d9303ca7be3
--- /dev/null
+++ b/sdk/lib/_internal/compiler/implementation/inferrer/ir_type_inferrer.dart
@@ -0,0 +1,86 @@
+// 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 dart2js.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, FunctionElement, FunctionSignature;
+import '../dart2jslib.dart' show Compiler, Constant, ConstantSystem;
+import 'type_graph_inferrer.dart' show TypeInformation;
+
+class IrTypeInferrerVisitor extends IrNodesVisitor {
+  final Compiler compiler;
+  final Element analyzedElement;
+  final TypeSystem<TypeInformation> types;
+  final InferrerEngine<TypeInformation, TypeSystem<TypeInformation>> inferrer;
+
+  IrTypeInferrerVisitor(this.compiler,
+                        this.analyzedElement,
+                        InferrerEngine<TypeInformation,
+                        TypeSystem<TypeInformation>> inferrer)
+    : inferrer = inferrer,
+      types = inferrer.types;
+
+  final Map<IrNode, TypeInformation> analyzed = <IrNode, TypeInformation>{};
+
+  TypeInformation returnType;
+
+  TypeInformation run() {
+    if (analyzedElement.isField()) {
+      // TODO(lry): handle fields.
+      throw "Type infer from IR for field $analyzedElement";
+    }
+    FunctionElement function = analyzedElement;
+    FunctionSignature signature = function.computeSignature(compiler);
+    IrFunction node = compiler.irBuilder.getIr(function);
+    // TODO(lry): handle parameters.
+
+    if (function.isNative()) {
+      // TODO(lry): handle native.
+      throw "Type infer from IR for native $analyzedElement";
+    }
+
+    if (analyzedElement.isGenerativeConstructor()) {
+      // TODO(lry): handle constructors.
+      throw "Type infer from IR for constructor $analyzedElement";
+    }
+
+    if (analyzedElement.isSynthesized) {
+      // TODO(lry): handle synthethics.
+      throw "Type infer from IR for synthetic $analyzedElement";
+    }
+
+    visitAll(node.statements);
+    return returnType;
+  }
+
+  TypeInformation 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");
+  }
+
+  void visitIrConstant(IrConstant node) {
+    analyzed[node] = typeOfConstant(node.value);
+  }
+
+  void visitIrReturn(IrReturn node) {
+    TypeInformation type = analyzed[node.value];
+    returnType = inferrer.addReturnTypeFor(analyzedElement, returnType, type);
+  }
+
+  void visitNode(IrNode node) {
+    compiler.internalError('Unexpected IrNode $node');
+  }
+}