Add atomic method reference map

Less RAM usage and faster than using a normal map with
MethodReference. Speed is faster by avoiding locking and tree
traversal. RAM usage is lower since the map usually had a value
for most method references.

Plan on using for marking methods for dex2dex, storing compiled
methods. Also use the new map for VerifiedMethods (refactoring).

Added test.

Bug: 32641252

Test: test-art-host-run-test

Change-Id: I46268031b8e0daf9be3597145cf6ecf579a039e2
diff --git a/compiler/utils/atomic_method_ref_map-inl.h b/compiler/utils/atomic_method_ref_map-inl.h
new file mode 100644
index 0000000..70ea028
--- /dev/null
+++ b/compiler/utils/atomic_method_ref_map-inl.h
@@ -0,0 +1,83 @@
+/*
+ * 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_COMPILER_UTILS_ATOMIC_METHOD_REF_MAP_INL_H_
+#define ART_COMPILER_UTILS_ATOMIC_METHOD_REF_MAP_INL_H_
+
+#include "atomic_method_ref_map.h"
+
+#include "dex_file-inl.h"
+
+namespace art {
+
+template <typename T>
+inline typename AtomicMethodRefMap<T>::InsertResult AtomicMethodRefMap<T>::Insert(
+    MethodReference ref,
+    const T& expected,
+    const T& desired) {
+  ElementArray* const array = GetArray(ref.dex_file);
+  if (array == nullptr) {
+    return kInsertResultInvalidDexFile;
+  }
+  return (*array)[ref.dex_method_index].CompareExchangeStrongSequentiallyConsistent(
+      expected, desired)
+      ? kInsertResultSuccess
+      : kInsertResultCASFailure;
+}
+
+template <typename T>
+inline bool AtomicMethodRefMap<T>::Get(MethodReference ref, T* out) const {
+  const ElementArray* const array = GetArray(ref.dex_file);
+  if (array == nullptr) {
+    return kInsertResultInvalidDexFile;
+  }
+  *out = (*array)[ref.dex_method_index].LoadRelaxed();
+  return true;
+}
+
+template <typename T>
+inline void AtomicMethodRefMap<T>::AddDexFile(const DexFile* dex_file) {
+  arrays_.Put(dex_file, std::move(ElementArray(dex_file->NumMethodIds())));
+}
+
+template <typename T>
+inline typename AtomicMethodRefMap<T>::ElementArray* AtomicMethodRefMap<T>::GetArray(
+    const DexFile* dex_file) {
+  auto it = arrays_.find(dex_file);
+  return (it != arrays_.end()) ? &it->second : nullptr;
+}
+
+template <typename T>
+inline const typename AtomicMethodRefMap<T>::ElementArray* AtomicMethodRefMap<T>::GetArray(
+    const DexFile* dex_file) const {
+  auto it = arrays_.find(dex_file);
+  return (it != arrays_.end()) ? &it->second : nullptr;
+}
+
+template <typename T> template <typename Visitor>
+inline void AtomicMethodRefMap<T>::Visit(const Visitor& visitor) {
+  for (auto& pair : arrays_) {
+    const DexFile* dex_file = pair.first;
+    const ElementArray& elements = pair.second;
+    for (size_t i = 0; i < elements.size(); ++i) {
+      visitor(MethodReference(dex_file, i), elements[i].LoadRelaxed());
+    }
+  }
+}
+
+}  // namespace art
+
+#endif  // ART_COMPILER_UTILS_ATOMIC_METHOD_REF_MAP_INL_H_
diff --git a/compiler/utils/atomic_method_ref_map.h b/compiler/utils/atomic_method_ref_map.h
new file mode 100644
index 0000000..f0db231
--- /dev/null
+++ b/compiler/utils/atomic_method_ref_map.h
@@ -0,0 +1,67 @@
+/*
+ * 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_COMPILER_UTILS_ATOMIC_METHOD_REF_MAP_H_
+#define ART_COMPILER_UTILS_ATOMIC_METHOD_REF_MAP_H_
+
+#include "base/dchecked_vector.h"
+#include "method_reference.h"
+#include "safe_map.h"
+
+namespace art {
+
+class DexFile;
+
+// Used by CompilerCallbacks to track verification information from the Runtime.
+template <typename T>
+class AtomicMethodRefMap {
+ public:
+  explicit AtomicMethodRefMap() {}
+  ~AtomicMethodRefMap() {}
+
+  // Atomically swap the element in if the existing value matches expected.
+  enum InsertResult {
+    kInsertResultInvalidDexFile,
+    kInsertResultCASFailure,
+    kInsertResultSuccess,
+  };
+  InsertResult Insert(MethodReference ref, const T& expected, const T& desired);
+
+  // Retreive an item, returns false if the dex file is not added.
+  bool Get(MethodReference ref, T* out) const;
+
+  // Dex files must be added before method references belonging to them can be used as keys. Not
+  // thread safe.
+  void AddDexFile(const DexFile* dex_file);
+
+  // Visit all of the dex files and elements.
+  template <typename Visitor>
+  void Visit(const Visitor& visitor);
+
+ private:
+  // Verified methods. The method array is fixed to avoid needing a lock to extend it.
+  using ElementArray = dchecked_vector<Atomic<T>>;
+  using DexFileArrays = SafeMap<const DexFile*, ElementArray>;
+
+  const ElementArray* GetArray(const DexFile* dex_file) const;
+  ElementArray* GetArray(const DexFile* dex_file);
+
+  DexFileArrays arrays_;
+};
+
+}  // namespace art
+
+#endif  // ART_COMPILER_UTILS_ATOMIC_METHOD_REF_MAP_H_
diff --git a/compiler/utils/atomic_method_ref_map_test.cc b/compiler/utils/atomic_method_ref_map_test.cc
new file mode 100644
index 0000000..c3e48ff
--- /dev/null
+++ b/compiler/utils/atomic_method_ref_map_test.cc
@@ -0,0 +1,69 @@
+/*
+ * 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.
+ */
+
+#include "atomic_method_ref_map-inl.h"
+
+#include <memory>
+
+#include "common_runtime_test.h"
+#include "dex_file-inl.h"
+#include "method_reference.h"
+#include "scoped_thread_state_change-inl.h"
+
+namespace art {
+
+class AtomicMethodRefMapTest : public CommonRuntimeTest {};
+
+TEST_F(AtomicMethodRefMapTest, RunTests) {
+  ScopedObjectAccess soa(Thread::Current());
+  std::unique_ptr<const DexFile> dex(OpenTestDexFile("Interfaces"));
+  ASSERT_TRUE(dex != nullptr);
+  using Map = AtomicMethodRefMap<int>;
+  Map map;
+  int value = 123;
+  // Error case: Not already inserted.
+  EXPECT_FALSE(map.Get(MethodReference(dex.get(), 1), &value));
+  // Error case: Dex file not registered.
+  EXPECT_TRUE(map.Insert(MethodReference(dex.get(), 1), 0, 1) == Map::kInsertResultInvalidDexFile);
+  map.AddDexFile(dex.get());
+  EXPECT_GT(dex->NumMethodIds(), 10u);
+  // After we have added the get should succeed but return the default value.
+  EXPECT_TRUE(map.Get(MethodReference(dex.get(), 1), &value));
+  EXPECT_EQ(value, 0);
+  // Actually insert an item and make sure we can retreive it.
+  static const int kInsertValue = 44;
+  EXPECT_TRUE(map.Insert(MethodReference(dex.get(), 1), 0, kInsertValue) ==
+              Map::kInsertResultSuccess);
+  EXPECT_TRUE(map.Get(MethodReference(dex.get(), 1), &value));
+  EXPECT_EQ(value, kInsertValue);
+  static const int kInsertValue2 = 123;
+  EXPECT_TRUE(map.Insert(MethodReference(dex.get(), 2), 0, kInsertValue2) ==
+              Map::kInsertResultSuccess);
+  EXPECT_TRUE(map.Get(MethodReference(dex.get(), 1), &value));
+  EXPECT_EQ(value, kInsertValue);
+  EXPECT_TRUE(map.Get(MethodReference(dex.get(), 2), &value));
+  EXPECT_EQ(value, kInsertValue2);
+  // Error case: Incorrect expected value for CAS.
+  EXPECT_TRUE(map.Insert(MethodReference(dex.get(), 1), 0, kInsertValue + 1) ==
+      Map::kInsertResultCASFailure);
+  // Correctly overwrite the value and verify.
+  EXPECT_TRUE(map.Insert(MethodReference(dex.get(), 1), kInsertValue, kInsertValue + 1) ==
+      Map::kInsertResultSuccess);
+  EXPECT_TRUE(map.Get(MethodReference(dex.get(), 1), &value));
+  EXPECT_EQ(value, kInsertValue + 1);
+}
+
+}  // namespace art