test/496-checker-inlining-class-loader/src/Main.java

/*
 * Copyright (C) 2015 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.
 */

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;

class MyClassLoader extends ClassLoader {
    MyClassLoader() throws Exception {
        super(MyClassLoader.class.getClassLoader());

        // Some magic to get access to the pathList field of BaseDexClassLoader.
        ClassLoader loader = getClass().getClassLoader();
        Class<?> baseDexClassLoader = loader.getClass().getSuperclass();
        Field f = baseDexClassLoader.getDeclaredField("pathList");
        f.setAccessible(true);
        Object pathList = f.get(loader);

        // Some magic to get access to the dexField field of pathList.
        // Need to make a copy of the dex elements since we don't want an app image
        // with pre-resolved things.
        f = pathList.getClass().getDeclaredField("dexElements");
        f.setAccessible(true);
        Object[] dexElements = (Object[]) f.get(pathList);
        f = dexElements[0].getClass().getDeclaredField("dexFile");
        f.setAccessible(true);
        for (Object element : dexElements) {
            Object dexFile = f.get(element);
            // Make copy.
            Field fileNameField = dexFile.getClass().getDeclaredField("mFileName");
            fileNameField.setAccessible(true);
            dexFiles.add(dexFile.getClass().getDeclaredConstructor(String.class).newInstance(
                fileNameField.get(dexFile)));
        }
    }

    ArrayList<Object> dexFiles = new ArrayList<Object>();
    Field dexFileField;

    protected Class<?> loadClass(String className, boolean resolve) throws ClassNotFoundException {
        // Other classes may also get loaded, ignore those.
        if (className.equals("LoadedByMyClassLoader")
                || className.equals("FirstSeenByMyClassLoader")) {
            System.out.println("Request for " + className);
        }

        // We're only going to handle LoadedByMyClassLoader.
        if (className != "LoadedByMyClassLoader") {
            return getParent().loadClass(className);
        }

        // Mimic what DexPathList.findClass is doing.
        try {
            for (Object dexFile : dexFiles) {
                Method method = dexFile.getClass().getDeclaredMethod(
                        "loadClassBinaryName", String.class, ClassLoader.class, List.class);

                if (dexFile != null) {
                    Class<?> clazz = (Class<?>) method.invoke(dexFile, className, this, null);
                    if (clazz != null) {
                        return clazz;
                    }
                }
            }
        } catch (Exception e) { /* Ignore */ }
        return null;
    }
}

class LoadedByMyClassLoader {
    /// CHECK-START: void LoadedByMyClassLoader.bar() inliner (before)
    /// CHECK:      LoadClass class_name:FirstSeenByMyClassLoader
    /// CHECK-NEXT: ClinitCheck
    /// CHECK-NEXT: InvokeStaticOrDirect
    /// CHECK-NEXT: LoadClass class_name:java.lang.System
    /// CHECK-NEXT: ClinitCheck
    /// CHECK-NEXT: StaticFieldGet
    /// CHECK-NEXT: LoadString
    /// CHECK-NEXT: NullCheck
    /// CHECK-NEXT: InvokeVirtual

    /// CHECK-START: void LoadedByMyClassLoader.bar() inliner (after)
    /// CHECK:      LoadClass class_name:FirstSeenByMyClassLoader
    /// CHECK-NEXT: ClinitCheck
                  /* We inlined FirstSeenByMyClassLoader.$inline$bar */
    /// CHECK-NEXT: LoadClass class_name:java.lang.System
    /// CHECK-NEXT: ClinitCheck
    /// CHECK-NEXT: StaticFieldGet
    /// CHECK-NEXT: LoadString
    /// CHECK-NEXT: NullCheck
    /// CHECK-NEXT: InvokeVirtual

    /// CHECK-START: void LoadedByMyClassLoader.bar() register (before)
                   /* Load and initialize FirstSeenByMyClassLoader */
    /// CHECK:      LoadClass class_name:FirstSeenByMyClassLoader gen_clinit_check:true
                   /* Load and initialize System */
    // There may be HX86ComputeBaseMethodAddress here.
    /// CHECK:      LoadClass class_name:java.lang.System
    // The ClinitCheck may (PIC) or may not (non-PIC) be merged into the LoadClass.
    // (The merging checks for environment match but HLoadClass/kBootImageAddress
    // used for non-PIC mode does not have an environment at all.)
    /// CHECK:      StaticFieldGet
    // There may be HX86ComputeBaseMethodAddress here.
    /// CHECK:      LoadString
    /// CHECK-NEXT: NullCheck
    /// CHECK-NEXT: InvokeVirtual
    public static void bar() {
        FirstSeenByMyClassLoader.$inline$bar();
        System.out.println("In between the two calls.");
        FirstSeenByMyClassLoader.$noinline$bar();
    }
}

public class Main {
    public static void main(String[] args) throws Exception {
        MyClassLoader o = new MyClassLoader();
        Class<?> foo = o.loadClass("LoadedByMyClassLoader");
        Method m = foo.getDeclaredMethod("bar");
        m.invoke(null);
    }
}