// Copyright (c) 2017, 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.cf.code;

import com.android.tools.r8.cf.CfPrinter;
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.CfCompareHelper;
import com.android.tools.r8.graph.DexItemFactory;
import com.android.tools.r8.graph.GraphLens;
import com.android.tools.r8.graph.InitClassLens;
import com.android.tools.r8.graph.ProgramMethod;
import com.android.tools.r8.ir.code.ValueType;
import com.android.tools.r8.ir.conversion.CfSourceCode;
import com.android.tools.r8.ir.conversion.CfState;
import com.android.tools.r8.ir.conversion.CfState.Slot;
import com.android.tools.r8.ir.conversion.IRBuilder;
import com.android.tools.r8.ir.conversion.LensCodeRewriterUtils;
import com.android.tools.r8.ir.optimize.Inliner.ConstraintWithTarget;
import com.android.tools.r8.ir.optimize.InliningConstraints;
import com.android.tools.r8.naming.NamingLens;
import com.android.tools.r8.optimize.interfaces.analysis.CfAnalysisConfig;
import com.android.tools.r8.optimize.interfaces.analysis.CfFrameState;
import com.android.tools.r8.utils.TraversalContinuation;
import com.android.tools.r8.utils.structural.CompareToVisitor;
import java.util.function.BiFunction;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;

public class CfReturn extends CfJumpInstruction {

  private final ValueType type;

  public CfReturn(ValueType type) {
    this.type = type;
  }

  public ValueType getType() {
    return type;
  }

  @Override
  public int getCompareToId() {
    return getOpcode();
  }

  @Override
  public int internalAcceptCompareTo(
      CfInstruction other, CompareToVisitor visitor, CfCompareHelper helper) {
    return CfCompareHelper.compareIdUniquelyDeterminesEquality(this, other);
  }

  private int getOpcode() {
    switch (type) {
      case INT:
        return Opcodes.IRETURN;
      case FLOAT:
        return Opcodes.FRETURN;
      case LONG:
        return Opcodes.LRETURN;
      case DOUBLE:
        return Opcodes.DRETURN;
      case OBJECT:
        return Opcodes.ARETURN;
      default:
        throw new Unreachable("Unexpected return type: " + type);
    }
  }

  @Override
  public int bytecodeSizeUpperBound() {
    return 1;
  }

  @Override
  public <BT, CT> TraversalContinuation<BT, CT> traverseNormalTargets(
      BiFunction<? super CfInstruction, ? super CT, TraversalContinuation<BT, CT>> fn,
      CfInstruction fallthroughInstruction,
      CT initialValue) {
    return TraversalContinuation.doContinue(initialValue);
  }

  @Override
  public void write(
      AppView<?> appView,
      ProgramMethod context,
      DexItemFactory dexItemFactory,
      GraphLens graphLens,
      InitClassLens initClassLens,
      NamingLens namingLens,
      LensCodeRewriterUtils rewriter,
      MethodVisitor visitor) {
    visitor.visitInsn(getOpcode());
  }

  @Override
  public void print(CfPrinter printer) {
    printer.print(this);
  }

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

  @Override
  public CfReturn asReturn() {
    return this;
  }

  @Override
  public void buildIR(IRBuilder builder, CfState state, CfSourceCode code) {
    Slot pop = state.pop();
    builder.addReturn(pop.register);
  }

  @Override
  public ConstraintWithTarget inliningConstraint(
      InliningConstraints inliningConstraints, CfCode code, ProgramMethod context) {
    return inliningConstraints.forReturn();
  }

  @Override
  public CfFrameState evaluate(CfFrameState frame, AppView<?> appView, CfAnalysisConfig config) {
    assert !config.getCurrentContext().getReturnType().isVoidType();
    return frame
        .popInitialized(appView, config, config.getCurrentContext().getReturnType())
        .clear();
  }
}