Implement class id checks as a separate instruction and add a local CSE optimization pass.

runtime/vm/hash_map_test.cc

+// Copyright (c) 2012, 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.
+
+#include "platform/assert.h"
+#include "vm/unit_test.h"
+#include "vm/hash_map.h"
+
+namespace dart {
+
+class TestValue {
+ public:
+  explicit TestValue(intptr_t x) : x_(x) { }
+  intptr_t Hashcode() const { return x_ & 1; }
+  bool Equals(TestValue* other) { return x_ == other->x_; }
+ private:
+  intptr_t x_;
+};
+
+
+TEST_CASE(DirectChainedHashMap) {
+  DirectChainedHashMap<TestValue*> map;
+  EXPECT(map.IsEmpty());
+  TestValue v1(0);
+  TestValue v2(1);
+  TestValue v3(0);
+  map.Insert(&v1);
+  EXPECT(map.Lookup(&v1) == &v1);
+  map.Insert(&v2);
+  EXPECT(map.Lookup(&v1) == &v1);
+  EXPECT(map.Lookup(&v2) == &v2);
+  EXPECT(map.Lookup(&v3) == &v1);
+}
+
+}  // namespace dart