ART: Switch to name-based IMT hashing
Use a hash scheme based on the name. This keeps IMT slots stable
when dex tables change.
This incurs a severe performance penalty for computing the slot.
Measurements on host degraded from 30ns to an average of 85mus.
However, calls in compiled code will not incur this overhead.
Added a test comparing similar interfaces in similar dex files.
Bug: 31594153
Test: test-art-host
Change-Id: Ibb86679ee94bec561984ea25826e56b1a7964cd0
diff --git a/runtime/imtable_test.cc b/runtime/imtable_test.cc
new file mode 100644
index 0000000..8cbe291
--- /dev/null
+++ b/runtime/imtable_test.cc
@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) 2011 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 "imtable-inl.h"
+
+#include <memory>
+#include <string>
+
+#include "jni.h"
+
+#include "base/mutex.h"
+#include "class_linker.h"
+#include "common_runtime_test.h"
+#include "mirror/accessible_object.h"
+#include "mirror/class.h"
+#include "mirror/class_loader.h"
+#include "handle_scope-inl.h"
+#include "scoped_thread_state_change-inl.h"
+#include "thread-inl.h"
+
+namespace art {
+
+class ImTableTest : public CommonRuntimeTest {
+ public:
+ std::pair<mirror::Class*, mirror::Class*> LoadClasses(const std::string& class_name)
+ REQUIRES_SHARED(Locks::mutator_lock_) {
+ jobject jclass_loader_a = LoadDex("IMTA");
+ CHECK(jclass_loader_a != nullptr);
+ jobject jclass_loader_b = LoadDex("IMTB");
+ CHECK(jclass_loader_b != nullptr);
+
+ ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
+ Thread* self = Thread::Current();
+
+ StackHandleScope<3> hs(self);
+ MutableHandle<mirror::ClassLoader> h_class_loader = hs.NewHandle<mirror::ClassLoader>(nullptr);
+
+ // A.
+ h_class_loader.Assign(
+ ObjPtr<mirror::ClassLoader>::DownCast(self->DecodeJObject(jclass_loader_a)));
+ Handle<mirror::Class> h_class_a(
+ hs.NewHandle(class_linker->FindClass(self, class_name.c_str(), h_class_loader)));
+ if (h_class_a.Get() == nullptr) {
+ LOG(ERROR) << self->GetException()->Dump();
+ CHECK(false) << "h_class_a == nullptr";
+ }
+
+ // B.
+ h_class_loader.Assign(
+ ObjPtr<mirror::ClassLoader>::DownCast(self->DecodeJObject(jclass_loader_b)));
+ Handle<mirror::Class> h_class_b(
+ hs.NewHandle(class_linker->FindClass(self, class_name.c_str(), h_class_loader)));
+ if (h_class_b.Get() == nullptr) {
+ LOG(ERROR) << self->GetException()->Dump();
+ CHECK(false) << "h_class_b == nullptr";
+ }
+
+ return std::make_pair(h_class_a.Get(), h_class_b.Get());
+ }
+
+ std::pair<ArtMethod*, ArtMethod*> LoadMethods(const std::string& class_name,
+ const std::string& method_name)
+ REQUIRES_SHARED(Locks::mutator_lock_) {
+ std::pair<mirror::Class*, mirror::Class*> classes = LoadClasses(class_name);
+
+ const PointerSize pointer_size = Runtime::Current()->GetClassLinker()->GetImagePointerSize();
+
+ ArtMethod* method_a =
+ classes.first->FindDeclaredVirtualMethodByName(method_name, pointer_size);
+ ArtMethod* method_b =
+ classes.second->FindDeclaredVirtualMethodByName(method_name, pointer_size);
+
+ return std::make_pair(method_a, method_b);
+ }
+};
+
+TEST_F(ImTableTest, NewMethodBefore) {
+ ScopedObjectAccess soa(Thread::Current());
+
+ std::pair<ArtMethod*, ArtMethod*> methods = LoadMethods("LInterfaces$A;", "foo");
+ CHECK_EQ(ImTable::GetImtIndex(methods.first), ImTable::GetImtIndex(methods.second));
+}
+
+TEST_F(ImTableTest, NewClassBefore) {
+ ScopedObjectAccess soa(Thread::Current());
+
+ std::pair<ArtMethod*, ArtMethod*> methods = LoadMethods("LInterfaces$Z;", "foo");
+ CHECK_EQ(ImTable::GetImtIndex(methods.first), ImTable::GetImtIndex(methods.second));
+}
+
+} // namespace art