src/main/java/com/android/tools/r8/optimize/MemberRebindingLens.java

// Copyright (c) 2018, 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.optimize;

import static com.android.tools.r8.graph.lens.NestedGraphLens.mapVirtualInterfaceInvocationTypes;

import com.android.tools.r8.graph.AppInfoWithClassHierarchy;
import com.android.tools.r8.graph.AppView;
import com.android.tools.r8.graph.DexField;
import com.android.tools.r8.graph.DexItemFactory;
import com.android.tools.r8.graph.DexMethod;
import com.android.tools.r8.graph.FieldAccessInfo;
import com.android.tools.r8.graph.lens.DefaultNonIdentityGraphLens;
import com.android.tools.r8.graph.lens.FieldLookupResult;
import com.android.tools.r8.graph.lens.GraphLens;
import com.android.tools.r8.graph.lens.MethodLookupResult;
import com.android.tools.r8.graph.lens.NonIdentityGraphLens;
import com.android.tools.r8.ir.code.InvokeType;
import com.android.tools.r8.shaking.AppInfoWithLiveness;
import java.util.Collections;
import java.util.IdentityHashMap;
import java.util.Map;

public class MemberRebindingLens extends DefaultNonIdentityGraphLens {

  private final AppView<AppInfoWithLiveness> appView;
  private final Map<InvokeType, Map<DexMethod, DexMethod>> methodMaps;
  private final Map<DexField, DexField> nonReboundFieldReferenceToDefinitionMap;

  public MemberRebindingLens(
      AppView<AppInfoWithLiveness> appView,
      Map<InvokeType, Map<DexMethod, DexMethod>> methodMaps,
      Map<DexField, DexField> nonReboundFieldReferenceToDefinitionMap) {
    super(appView.dexItemFactory(), appView.graphLens());
    this.appView = appView;
    this.methodMaps = methodMaps;
    this.nonReboundFieldReferenceToDefinitionMap = nonReboundFieldReferenceToDefinitionMap;
  }

  public static Builder builder(AppView<AppInfoWithLiveness> appView) {
    return new Builder(appView);
  }

  @Override
  public boolean isMemberRebindingLens() {
    return true;
  }

  @Override
  public MemberRebindingLens asMemberRebindingLens() {
    return this;
  }

  @Override
  protected FieldLookupResult internalDescribeLookupField(FieldLookupResult previous) {
    assert !previous.hasReadCastType();
    assert !previous.hasReboundReference();
    return FieldLookupResult.builder(this)
        .setReference(previous.getReference())
        .setReboundReference(getReboundFieldReference(previous.getReference()))
        .build();
  }

  private DexField getReboundFieldReference(DexField field) {
    return nonReboundFieldReferenceToDefinitionMap.getOrDefault(field, field);
  }

  @Override
  public MethodLookupResult internalDescribeLookupMethod(
      MethodLookupResult previous, DexMethod context, GraphLens codeLens) {
    Map<DexMethod, DexMethod> methodMap =
        methodMaps.getOrDefault(previous.getType(), Collections.emptyMap());
    DexMethod newMethod = methodMap.get(previous.getReference());
    if (newMethod == null) {
      return previous;
    }
    return MethodLookupResult.builder(this)
        .setReference(newMethod)
        .setPrototypeChanges(previous.getPrototypeChanges())
        .setType(
            mapVirtualInterfaceInvocationTypes(
                appView, newMethod, previous.getReference(), previous.getType()))
        .build();
  }

  public FieldRebindingIdentityLens toRewrittenFieldRebindingLens(
      AppView<? extends AppInfoWithClassHierarchy> appView,
      GraphLens lens,
      NonIdentityGraphLens appliedMemberRebindingLens) {
    DexItemFactory dexItemFactory = appView.dexItemFactory();
    FieldRebindingIdentityLens.Builder builder = FieldRebindingIdentityLens.builder();
    nonReboundFieldReferenceToDefinitionMap.forEach(
        (nonReboundFieldReference, reboundFieldReference) -> {
          DexField rewrittenReboundFieldReference =
              lens.getRenamedFieldSignature(reboundFieldReference, appliedMemberRebindingLens);
          DexField rewrittenNonReboundFieldReference =
              rewrittenReboundFieldReference.withHolder(
                  lens.lookupType(
                      nonReboundFieldReference.getHolderType(), appliedMemberRebindingLens),
                  dexItemFactory);
          builder.recordDefinitionForNonReboundFieldReference(
              rewrittenNonReboundFieldReference, rewrittenReboundFieldReference);
        });
    return builder.build(dexItemFactory);
  }

  public static class Builder {

    private final AppView<AppInfoWithLiveness> appView;
    private final Map<InvokeType, Map<DexMethod, DexMethod>> methodMaps = new IdentityHashMap<>();
    private final Map<DexField, DexField> nonReboundFieldReferenceToDefinitionMap =
        new IdentityHashMap<>();

    private Builder(AppView<AppInfoWithLiveness> appView) {
      this.appView = appView;
    }

    public void map(DexMethod from, DexMethod to, InvokeType type) {
      if (from == to) {
        assert !methodMaps.containsKey(type) || methodMaps.get(type).getOrDefault(from, to) == to;
        return;
      }
      Map<DexMethod, DexMethod> methodMap =
          methodMaps.computeIfAbsent(type, ignore -> new IdentityHashMap<>());
      assert methodMap.getOrDefault(from, to) == to;
      methodMap.put(from, to);
    }

    void recordNonReboundFieldAccesses(FieldAccessInfo info) {
      DexField reboundFieldReference = info.getField();
      info.forEachIndirectAccess(
          nonReboundFieldReference ->
              recordNonReboundFieldAccess(nonReboundFieldReference, reboundFieldReference));
    }

    private void recordNonReboundFieldAccess(
        DexField nonReboundFieldReference, DexField reboundFieldReference) {
      nonReboundFieldReferenceToDefinitionMap.put(nonReboundFieldReference, reboundFieldReference);
    }

    public MemberRebindingLens build() {
      return new MemberRebindingLens(appView, methodMaps, nonReboundFieldReferenceToDefinitionMap);
    }
  }
}