src/main/java/com/android/tools/r8/ir/optimize/info/initializer/NonTrivialInstanceInitializerInfo.java

// Copyright (c) 2019, 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.info.initializer;

import com.android.tools.r8.graph.DexEncodedField;
import com.android.tools.r8.ir.analysis.fieldvalueanalysis.AbstractFieldSet;
import com.android.tools.r8.ir.analysis.fieldvalueanalysis.ConcreteMutableFieldSet;
import com.android.tools.r8.ir.analysis.fieldvalueanalysis.EmptyFieldSet;
import com.android.tools.r8.ir.analysis.fieldvalueanalysis.UnknownFieldSet;

public final class NonTrivialInstanceInitializerInfo extends InstanceInitializerInfo {

  private static final int INSTANCE_FIELD_INITIALIZATION_INDEPENDENT_OF_ENVIRONMENT = 1 << 0;
  private static final int NO_OTHER_SIDE_EFFECTS_THAN_INSTANCE_FIELD_ASSIGNMENTS = 1 << 1;
  private static final int RECEIVER_NEVER_ESCAPE_OUTSIDE_CONSTRUCTOR_CHAIN = 1 << 2;

  private final int data;
  private final AbstractFieldSet readSet;

  private NonTrivialInstanceInitializerInfo(int data, AbstractFieldSet readSet) {
    assert verifyNoUnknownBits(data);
    this.data = data;
    this.readSet = readSet;
  }

  private static boolean verifyNoUnknownBits(int data) {
    int knownBits =
        INSTANCE_FIELD_INITIALIZATION_INDEPENDENT_OF_ENVIRONMENT
            | NO_OTHER_SIDE_EFFECTS_THAN_INSTANCE_FIELD_ASSIGNMENTS
            | RECEIVER_NEVER_ESCAPE_OUTSIDE_CONSTRUCTOR_CHAIN;
    assert (data & ~knownBits) == 0;
    return true;
  }

  public static Builder builder() {
    return new Builder();
  }

  @Override
  public AbstractFieldSet readSet() {
    return readSet;
  }

  @Override
  public boolean instanceFieldInitializationMayDependOnEnvironment() {
    return (data & INSTANCE_FIELD_INITIALIZATION_INDEPENDENT_OF_ENVIRONMENT) == 0;
  }

  @Override
  public boolean mayHaveOtherSideEffectsThanInstanceFieldAssignments() {
    return (data & NO_OTHER_SIDE_EFFECTS_THAN_INSTANCE_FIELD_ASSIGNMENTS) == 0;
  }

  @Override
  public boolean receiverNeverEscapesOutsideConstructorChain() {
    return (data & RECEIVER_NEVER_ESCAPE_OUTSIDE_CONSTRUCTOR_CHAIN) != 0;
  }

  public static class Builder {

    private int data =
        INSTANCE_FIELD_INITIALIZATION_INDEPENDENT_OF_ENVIRONMENT
            | NO_OTHER_SIDE_EFFECTS_THAN_INSTANCE_FIELD_ASSIGNMENTS
            | RECEIVER_NEVER_ESCAPE_OUTSIDE_CONSTRUCTOR_CHAIN;
    private AbstractFieldSet readSet = EmptyFieldSet.getInstance();

    private boolean isTrivial() {
      return data == 0 && readSet.isTop();
    }

    public Builder markFieldAsRead(DexEncodedField field) {
      if (readSet.isKnownFieldSet()) {
        if (readSet.isBottom()) {
          readSet = new ConcreteMutableFieldSet(field);
        } else {
          readSet.asConcreteFieldSet().add(field);
        }
      }
      assert readSet.contains(field);
      return this;
    }

    public Builder markAllFieldsAsRead() {
      readSet = UnknownFieldSet.getInstance();
      return this;
    }

    public Builder setInstanceFieldInitializationMayDependOnEnvironment() {
      data &= ~INSTANCE_FIELD_INITIALIZATION_INDEPENDENT_OF_ENVIRONMENT;
      return this;
    }

    public Builder setMayHaveOtherSideEffectsThanInstanceFieldAssignments() {
      data &= ~NO_OTHER_SIDE_EFFECTS_THAN_INSTANCE_FIELD_ASSIGNMENTS;
      return this;
    }

    public Builder setReceiverMayEscapeOutsideConstructorChain() {
      data &= ~RECEIVER_NEVER_ESCAPE_OUTSIDE_CONSTRUCTOR_CHAIN;
      return this;
    }

    public InstanceInitializerInfo build() {
      return isTrivial()
          ? DefaultInstanceInitializerInfo.getInstance()
          : new NonTrivialInstanceInitializerInfo(data, readSet);
    }
  }
}