src/main/java/com/android/tools/r8/ir/code/ArrayGet.java

// 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.code.Aget;
import com.android.tools.r8.code.AgetBoolean;
import com.android.tools.r8.code.AgetByte;
import com.android.tools.r8.code.AgetChar;
import com.android.tools.r8.code.AgetObject;
import com.android.tools.r8.code.AgetShort;
import com.android.tools.r8.code.AgetWide;
import com.android.tools.r8.dex.Constants;
import com.android.tools.r8.errors.Unreachable;
import com.android.tools.r8.graph.AppInfoWithSubtyping;
import com.android.tools.r8.graph.DexType;
import com.android.tools.r8.ir.conversion.DexBuilder;
import com.android.tools.r8.ir.optimize.Inliner.Constraint;
import com.android.tools.r8.ir.regalloc.RegisterAllocator;
import java.util.Arrays;

public class ArrayGet extends Instruction {

  private final MemberType type;

  public ArrayGet(MemberType type, Value dest, Value array, Value index) {
    super(dest, Arrays.asList(array, index));
    this.type = type;
  }

  public Value dest() {
    return outValue;
  }

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

  public Value index() {
    return inValues.get(1);
  }

  @Override
  public void buildDex(DexBuilder builder) {
    int dest = builder.allocatedRegister(dest(), getNumber());
    int array = builder.allocatedRegister(array(), getNumber());
    int index = builder.allocatedRegister(index(), getNumber());
    com.android.tools.r8.code.Instruction instruction;
    switch (type) {
      case SINGLE:
        instruction = new Aget(dest, array, index);
        break;
      case WIDE:
        instruction = new AgetWide(dest, array, index);
        break;
      case OBJECT:
        instruction = new AgetObject(dest, array, index);
        break;
      case BOOLEAN:
        instruction = new AgetBoolean(dest, array, index);
        break;
      case BYTE:
        instruction = new AgetByte(dest, array, index);
        break;
      case CHAR:
        instruction = new AgetChar(dest, array, index);
        break;
      case SHORT:
        instruction = new AgetShort(dest, array, index);
        break;
      default:
        throw new Unreachable("Unexpected type " + type);
    }
    builder.add(this, instruction);
  }

  @Override
  public boolean identicalAfterRegisterAllocation(Instruction other, RegisterAllocator allocator) {
    // We cannot share ArrayGet instructions without knowledge of the type of the array input.
    // If multiple primitive array types flow to the same ArrayGet instruction the art verifier
    // gets confused.
    return false;
  }

  @Override
  public boolean identicalNonValueParts(Instruction other) {
    return other.asArrayGet().type == type;
  }

  @Override
  public int compareNonValueParts(Instruction other) {
    return type.ordinal() - other.asArrayGet().type.ordinal();
  }

  @Override
  public int maxInValueRegister() {
    return Constants.U8BIT_MAX;
  }

  @Override
  public int maxOutValueRegister() {
    return Constants.U8BIT_MAX;
  }

  @Override
  public boolean instructionTypeCanThrow() {
    // TODO: Determine if the array index out-of-bounds exception cannot happen.
    return true;
  }

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

  @Override
  public ArrayGet asArrayGet() {
    return this;
  }

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