// Copyright (c) 2016, 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.code;

import com.android.tools.r8.cf.LoadStoreHelper;
import com.android.tools.r8.dex.Constants;
import com.android.tools.r8.errors.Unreachable;
import com.android.tools.r8.graph.AppInfo;
import com.android.tools.r8.graph.DexType;
import com.android.tools.r8.ir.analysis.type.TypeLatticeElement;
import com.android.tools.r8.ir.conversion.CfBuilder;
import com.android.tools.r8.ir.conversion.DexBuilder;
import com.android.tools.r8.ir.optimize.Inliner.Constraint;
import com.android.tools.r8.shaking.Enqueuer.AppInfoWithLiveness;
import java.util.function.Function;

public class Move extends Instruction {
  private static final String ERROR_MESSAGE =
      "This DEX-specific instruction should not be seen in the CF backend";

  public Move(Value dest, Value src) {
    super(dest, src);
    // CodeRewriter.removeOrReplaceByDebugLocalWrite() might add a Move to a dest that is already
    // marked never-null. Avoid tripping assertion in markNeverNull() in that case.
    if (src.isNeverNull() && dest.canBeNull()) {
      dest.markNeverNull();
    }
  }

  @Override
  boolean computeNeverNull() {
    return src().isNeverNull();
  }

  public Value dest() {
    return outValue;
  }

  public Value src() {
    return inValues.get(0);
  }

  @Override
  public void buildDex(DexBuilder builder) {
    builder.addMove(this);
  }

  @Override
  public void buildCf(CfBuilder builder) {
    throw new Unreachable(ERROR_MESSAGE);
  }

  @Override
  public int maxInValueRegister() {
    return Constants.U16BIT_MAX;
  }

  @Override
  public int maxOutValueRegister() {
    return Constants.U16BIT_MAX;
  }

  @Override
  public boolean identicalNonValueNonPositionParts(Instruction other) {
    return other.isMove();
  }

  @Override
  public int compareNonValueParts(Instruction other) {
    assert other.isMove();
    return 0;
  }

  @Override
  public String toString() {
    return super.toString() + " (" + outType() + ")";
  }

  @Override
  public boolean isOutConstant() {
    return src().isConstant();
  }

  @Override
  public ConstInstruction getOutConstantConstInstruction() {
    assert isOutConstant();
    return src().definition.getOutConstantConstInstruction();
  }

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

  @Override
  public Move asMove() {
    return this;
  }

  @Override
  public Constraint inliningConstraint(AppInfoWithLiveness info, DexType invocationContext) {
    return Constraint.ALWAYS;
  }

  @Override
  public TypeLatticeElement evaluate(
      AppInfo appInfo, Function<Value, TypeLatticeElement> getLatticeElement) {
    return getLatticeElement.apply(src());
  }

  @Override
  public void insertLoadAndStores(InstructionListIterator it, LoadStoreHelper helper) {
    throw new Unreachable(ERROR_MESSAGE);
  }
}