src/main/java/com/android/tools/r8/ir/optimize/library/LibraryFieldSynthesis.java

// Copyright (c) 2020, 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.android.tools.r8.ir.optimize.library;

import static com.android.tools.r8.graph.DexLibraryClass.asLibraryClassOrNull;

import com.android.tools.r8.dex.Constants;
import com.android.tools.r8.graph.AppView;
import com.android.tools.r8.graph.DexAnnotationSet;
import com.android.tools.r8.graph.DexEncodedField;
import com.android.tools.r8.graph.DexItemFactory;
import com.android.tools.r8.graph.DexLibraryClass;
import com.android.tools.r8.graph.FieldAccessFlags;
import com.android.tools.r8.graph.GenericSignature.FieldTypeSignature;

/**
 * This class synthesizes library fields that we rely on for modeling.
 *
 * <p>For example, we synthesize the field `java.lang.String java.lang.Enum.name` if it is not
 * present. We use this to model that the constructor `void java.lang.Enum.<init>(java.lang.String,
 * int)` initializes `java.lang.String java.lang.Enum.name` to the first argument of the
 * constructor.
 */
public class LibraryFieldSynthesis {

  public static void synthesizeEnumFields(AppView<?> appView) {
    DexItemFactory dexItemFactory = appView.dexItemFactory();
    DexLibraryClass enumClass =
        asLibraryClassOrNull(appView.definitionFor(dexItemFactory.enumType));
    if (enumClass != null) {
      dexItemFactory.enumMembers.forEachField(
          field -> {
            DexEncodedField definition = enumClass.lookupField(field);
            if (definition == null) {
              enumClass.appendInstanceField(
                  new DexEncodedField(
                      field,
                      FieldAccessFlags.fromCfAccessFlags(
                          Constants.ACC_PRIVATE | Constants.ACC_FINAL),
                      FieldTypeSignature.noSignature(),
                      DexAnnotationSet.empty(),
                      null));
            }
          });
    }
  }
}