src/main/java/com/android/tools/r8/verticalclassmerging/IncompleteVerticalClassMergerBridgeCode.java

// Copyright (c) 2024, 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.verticalclassmerging;

import com.android.tools.r8.errors.Unreachable;
import com.android.tools.r8.graph.AppView;
import com.android.tools.r8.graph.CfCode;
import com.android.tools.r8.graph.ClasspathMethod;
import com.android.tools.r8.graph.Code;
import com.android.tools.r8.graph.DexEncodedMethod;
import com.android.tools.r8.graph.DexItemFactory;
import com.android.tools.r8.graph.DexMethod;
import com.android.tools.r8.graph.ProgramMethod;
import com.android.tools.r8.graph.UseRegistry;
import com.android.tools.r8.ir.code.IRCode;
import com.android.tools.r8.ir.code.InvokeType;
import com.android.tools.r8.ir.conversion.MethodConversionOptions.MutableMethodConversionOptions;
import com.android.tools.r8.ir.synthetic.ForwardMethodBuilder;
import com.android.tools.r8.origin.Origin;
import com.android.tools.r8.utils.RetracerForCodePrinting;

/**
 * A short-lived piece of code that will be converted into {@link CfCode} using the method {@link
 * IncompleteVerticalClassMergerBridgeCode#toCfCode(DexItemFactory, VerticalClassMergerGraphLens)}.
 */
public class IncompleteVerticalClassMergerBridgeCode extends Code {

  private DexMethod method;
  private DexMethod invocationTarget;
  private final InvokeType type;
  private final boolean isInterface;

  public IncompleteVerticalClassMergerBridgeCode(
      DexMethod method, InvokeType type, boolean isInterface) {
    this.method = method;
    this.invocationTarget = null;
    this.type = type;
    this.isInterface = isInterface;
  }

  @Override
  public Code getCodeAsInlining(
      DexMethod caller,
      boolean isCallerD8R8Synthesized,
      DexMethod callee,
      boolean isCalleeD8R8Synthesized,
      DexItemFactory factory) {
    // This code object is synthesized so "inlining" just "strips" the callee position.
    assert isCalleeD8R8Synthesized;
    return this;
  }

  public DexMethod getMethod() {
    return method;
  }

  public DexMethod getTarget() {
    return invocationTarget;
  }

  // By the time the synthesized code object is created, vertical class merging still has not
  // finished. Therefore it is possible that the method signatures `method` and `invocationTarget`
  // will change as a result of additional class merging operations. To deal with this, the
  // vertical class merger explicitly invokes this method to update `method` and `invocation-
  // Target` when vertical class merging has finished.
  //
  // Note that, without this step, these method signatures might refer to intermediate signatures
  // that are only present in the middle of vertical class merging, which means that the graph
  // lens will not work properly (since the graph lens generated by vertical class merging only
  // expects to be applied to method signatures from *before* vertical class merging or *after*
  // vertical class merging).
  public void updateMethodSignatures(VerticalClassMergerGraphLens lens) {
    invocationTarget = lens.getNextImplementationMethodSignature(method);
    method = lens.getNextBridgeMethodSignature(method);
  }

  public CfCode toCfCode(DexItemFactory dexItemFactory, VerticalClassMergerGraphLens lens) {
    return ForwardMethodBuilder.builder(dexItemFactory)
        .applyIf(
            type.isStatic(),
            builder -> builder.setStaticTarget(invocationTarget, isInterface),
            builder -> builder.setVirtualTarget(invocationTarget, isInterface))
        .setNonStaticSource(method)
        .setCodeLens(lens)
        .build();
  }

  // Implement Code.

  @Override
  public IRCode buildIR(
      ProgramMethod method,
      AppView<?> appView,
      Origin origin,
      MutableMethodConversionOptions conversionOptions) {
    throw new Unreachable();
  }

  @Override
  protected boolean computeEquals(Object other) {
    throw new Unreachable();
  }

  @Override
  protected int computeHashCode() {
    throw new Unreachable();
  }

  @Override
  public int estimatedDexCodeSizeUpperBoundInBytes() {
    throw new Unreachable();
  }

  @Override
  public boolean isEmptyVoidMethod() {
    throw new Unreachable();
  }

  @Override
  public void registerCodeReferences(ProgramMethod method, UseRegistry registry) {
    throw new Unreachable();
  }

  @Override
  public void registerCodeReferencesForDesugaring(ClasspathMethod method, UseRegistry registry) {
    throw new Unreachable();
  }

  @Override
  public String toString() {
    return "IncompleteVerticalClassMergerBridgeCode";
  }

  @Override
  public String toString(DexEncodedMethod method, RetracerForCodePrinting retracer) {
    return toString();
  }
}