src/main/java/com/android/tools/r8/optimize/argumentpropagation/codescanner/AbstractFunction.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.optimize.argumentpropagation.codescanner;

import com.android.tools.r8.graph.AppView;
import com.android.tools.r8.shaking.AppInfoWithLiveness;

public interface AbstractFunction extends InFlow {

  static IdentityAbstractFunction identity() {
    return IdentityAbstractFunction.get();
  }

  static UnknownAbstractFunction unknown() {
    return UnknownAbstractFunction.get();
  }

  /**
   * Applies the current abstract function to its declared inputs (in {@link #getBaseInFlow()}).
   *
   * <p>It is guaranteed by the caller that the given {@param state} is the abstract state for the
   * field or parameter that caused this function to be reevaluated. If this abstract function takes
   * a single input, then {@param state} is guaranteed to be the state for the node returned by
   * {@link #getBaseInFlow()}, and {@param flowGraphStateProvider} should never be used.
   *
   * <p>Abstract functions that depend on multiple inputs can lookup the state for each input in
   * {@param flowGraphStateProvider}. Attempting to lookup the state of a non-declared input is an
   * error.
   */
  ValueState apply(
      AppView<AppInfoWithLiveness> appView,
      FlowGraphStateProvider flowGraphStateProvider,
      ConcreteValueState inState);

  /** Returns true if the given {@param inFlow} is a declared input of this abstract function. */
  boolean containsBaseInFlow(BaseInFlow inFlow);

  /**
   * Returns the program field or parameter graph nodes that this function depends on. Upon any
   * change to the abstract state of any of these nodes this abstract function must be re-evaluated.
   */
  Iterable<BaseInFlow> getBaseInFlow();

  @Override
  default boolean isAbstractFunction() {
    return true;
  }

  @Override
  default AbstractFunction asAbstractFunction() {
    return this;
  }

  default boolean isIdentity() {
    return false;
  }
}