src/main/java/com/android/tools/r8/cf/code/CfArrayLength.java

// 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.graph.AppView;
import com.android.tools.r8.graph.CfCompareHelper;
import com.android.tools.r8.graph.DexItemFactory;
import com.android.tools.r8.graph.ProgramMethod;
import com.android.tools.r8.graph.lens.GraphLens;
import com.android.tools.r8.graph.lens.InitClassLens;
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.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.structural.CompareToVisitor;
import com.android.tools.r8.utils.structural.HashingVisitor;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;

public class CfArrayLength extends CfInstruction {

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

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

  @Override
  public int getAsmOpcode() {
    return Opcodes.ARRAYLENGTH;
  }

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

  @Override
  public void internalAcceptHashing(HashingVisitor visitor) {
    // Nothing to add.
  }

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

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

  @Override
  public void buildIR(IRBuilder builder, CfState state, CfSourceCode code) {
    Slot array = state.pop();
    assert array.type.isObject();
    builder.addArrayLength(
        state.push(builder.appView.dexItemFactory().intType).register, array.register);
  }

  @Override
  public CfFrameState evaluate(CfFrameState frame, AppView<?> appView, CfAnalysisConfig config) {
    // ..., arrayref →
    // ..., length
    return frame.popArray(appView).push(config, appView.dexItemFactory().intType);
  }
}