[turbofan] Model arguments object materialization in graph.

test/cctest/compiler/test-run-jsobjects.cc

+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "test/cctest/compiler/function-tester.h"
+
+using namespace v8::internal;
+using namespace v8::internal::compiler;
+
+TEST(ArgumentsMapped) {
+  FunctionTester T("(function(a) { return arguments; })");
+
+  Handle<Object> arguments;
+  T.Call(T.Val(19), T.Val(23), T.Val(42), T.Val(65)).ToHandle(&arguments);
+  CHECK(arguments->IsJSObject() && !arguments->IsJSArray());
+  CHECK(JSObject::cast(*arguments)->HasSloppyArgumentsElements());
+  Handle<String> l = T.isolate->factory()->length_string();
+  Handle<Object> length = JSObject::GetProperty(arguments, l).ToHandleChecked();
+  CHECK_EQ(4, length->Number());
+}
+
+
+TEST(ArgumentsUnmapped) {
+  FunctionTester T("(function(a) { 'use strict'; return arguments; })");
+
+  Handle<Object> arguments;
+  T.Call(T.Val(19), T.Val(23), T.Val(42), T.Val(65)).ToHandle(&arguments);
+  CHECK(arguments->IsJSObject() && !arguments->IsJSArray());
+  CHECK(!JSObject::cast(*arguments)->HasSloppyArgumentsElements());
+  Handle<String> l = T.isolate->factory()->length_string();
+  Handle<Object> length = JSObject::GetProperty(arguments, l).ToHandleChecked();
+  CHECK_EQ(4, length->Number());
+}
+
+
+TEST(ArgumentsRest) {
+  FLAG_harmony_rest_parameters = true;
+  FunctionTester T("(function(a, ...args) { return args; })");
+
+  Handle<Object> arguments;
+  T.Call(T.Val(19), T.Val(23), T.Val(42), T.Val(65)).ToHandle(&arguments);
+  CHECK(arguments->IsJSObject() && arguments->IsJSArray());
+  CHECK(!JSObject::cast(*arguments)->HasSloppyArgumentsElements());
+  Handle<String> l = T.isolate->factory()->length_string();
+  Handle<Object> length = JSObject::GetProperty(arguments, l).ToHandleChecked();
+  CHECK_EQ(3, length->Number());
+}