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// Copyright (c) 2017, the R8 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.
package com.debughelper.tools.r8.shaking;
import com.debughelper.tools.r8.graph.AppInfoWithSubtyping;
import com.debughelper.tools.r8.graph.DexClass;
import com.debughelper.tools.r8.graph.DexEncodedMethod;
import com.debughelper.tools.r8.graph.DexType;
import com.debughelper.tools.r8.logging.Log;
import java.util.ArrayList;
import java.util.List;
/**
* Removes abstract methods if they only shadow methods of the same signature in a superclass.
*
* We do not consider classes from the library for this optimization, as the program might run
* against a different version of the library where methods are missing.
*
* This optimization is beneficial mostly as it removes superfluous abstract methods that are
* created by the {@link TreePruner}.
*/
public class AbstractMethodRemover {
private final AppInfoWithSubtyping appInfo;
private ScopedDexMethodSet scope = new ScopedDexMethodSet();
public AbstractMethodRemover(AppInfoWithSubtyping appInfo) {
this.appInfo = appInfo;
}
public void run() {
assert scope.getParent() == null;
processClass(appInfo.dexItemFactory.objectType);
}
private void processClass(DexType type) {
DexClass holder = appInfo.definitionFor(type);
scope = scope.newNestedScope();
if (holder != null && !holder.isLibraryClass()) {
holder.setVirtualMethods(processMethods(holder.virtualMethods()));
}
type.forAllExtendsSubtypes(this::processClass);
scope = scope.getParent();
}
private DexEncodedMethod[] processMethods(DexEncodedMethod[] virtualMethods) {
if (virtualMethods == null) {
return null;
}
// Removal of abstract methods is rare, so avoid copying the array until we find one.
List methods = null;
for (int i = 0; i < virtualMethods.length; i++) {
DexEncodedMethod method = virtualMethods[i];
if (scope.addMethodIfMoreVisible(method) || !method.accessFlags.isAbstract()) {
if (methods != null) {
methods.add(method);
}
} else {
if (methods == null) {
methods = new ArrayList<>(virtualMethods.length - 1);
for (int j = 0; j < i; j++) {
methods.add(virtualMethods[j]);
}
}
if (Log.ENABLED) {
Log.debug(getClass(), "Removing abstract method %s.", method.method);
}
}
}
return methods == null ? virtualMethods : methods.toArray(new DexEncodedMethod[methods.size()]);
}
}