src/main/java/com/android/tools/r8/ir/analysis/inlining/NullSimpleInliningConstraint.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.analysis.inlining;

import com.android.tools.r8.ir.code.InvokeMethod;
import com.android.tools.r8.ir.code.Value;
import it.unimi.dsi.fastutil.ints.IntList;

/** Constraint that is satisfied if a specific argument is always null. */
public class NullSimpleInliningConstraint extends SimpleInliningArgumentConstraint {

  private NullSimpleInliningConstraint(int argumentIndex) {
    super(argumentIndex);
  }

  static NullSimpleInliningConstraint create(
      int argumentIndex, SimpleInliningConstraintFactory witness) {
    assert witness != null;
    return new NullSimpleInliningConstraint(argumentIndex);
  }

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

  @Override
  public boolean isSatisfied(InvokeMethod invoke) {
    // Take the root value to also deal with the following case, which may happen in dead code,
    // where v1 is actually guaranteed to be null, despite the value's type being non-null:
    //   v0 <- ConstNumber 0
    //   v1 <- AssumeNotNull v0
    Value argumentRoot = getArgument(invoke).getAliasedValue();
    assert argumentRoot.getType().isReferenceType();
    return argumentRoot.getType().isDefinitelyNull();
  }

  @Override
  public SimpleInliningConstraint fixupAfterRemovingThisParameter(
      SimpleInliningConstraintFactory factory) {
    assert getArgumentIndex() > 0;
    return factory.createNullConstraint(getArgumentIndex() - 1);
  }

  @Override
  public SimpleInliningConstraint rewrittenWithUnboxedArguments(
      IntList unboxedArgumentIndices, SimpleInliningConstraintFactory factory) {
    if (unboxedArgumentIndices.contains(getArgumentIndex())) {
      return factory.createNumberConstraint(getArgumentIndex(), 0);
    }
    return this;
  }
}