Add and use loaded class profiling

Class profiling is a way to keep track of which classes are resolved.
From here the compiler can use this information to generate a smaller
app image.

TODO: Add tests for profile stuff.

Bug: 22858531

Change-Id: I91ccd686394cc2517512f66abb0e277f3d26d4da
diff --git a/runtime/dex_cache_resolved_classes.h b/runtime/dex_cache_resolved_classes.h
new file mode 100644
index 0000000..80c12cb
--- /dev/null
+++ b/runtime/dex_cache_resolved_classes.h
@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_RUNTIME_DEX_CACHE_RESOLVED_CLASSES_H_
+#define ART_RUNTIME_DEX_CACHE_RESOLVED_CLASSES_H_
+
+#include <string>
+#include <unordered_set>
+#include <vector>
+
+namespace art {
+
+// Data structure for passing around which classes belonging to a dex cache / dex file are resolved.
+class DexCacheResolvedClasses {
+ public:
+  DexCacheResolvedClasses(const std::string& dex_location, uint32_t location_checksum)
+      : dex_location_(dex_location),
+        location_checksum_(location_checksum) {}
+
+  // Only compare the key elements, ignore the resolved classes.
+  int Compare(const DexCacheResolvedClasses& other) const {
+    if (location_checksum_ != other.location_checksum_) {
+      return static_cast<int>(location_checksum_ - other.location_checksum_);
+    }
+    return dex_location_.compare(other.dex_location_);
+  }
+
+  template <class InputIt>
+  void AddClasses(InputIt begin, InputIt end) const {
+    classes_.insert(begin, end);
+  }
+
+  const std::string& GetDexLocation() const {
+    return dex_location_;
+  }
+
+  uint32_t GetLocationChecksum() const {
+    return location_checksum_;
+  }
+
+  const std::unordered_set<uint16_t>& GetClasses() const {
+    return classes_;
+  }
+
+ private:
+  const std::string dex_location_;
+  const uint32_t location_checksum_;
+  // Array of resolved class def indexes.
+  mutable std::unordered_set<uint16_t> classes_;
+};
+
+inline bool operator<(const DexCacheResolvedClasses& a, const DexCacheResolvedClasses& b) {
+  return a.Compare(b) < 0;
+}
+
+}  // namespace art
+
+#endif  // ART_RUNTIME_DEX_CACHE_RESOLVED_CLASSES_H_