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

// Copyright (c) 2018, 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.DexClassAndMethod;
import com.android.tools.r8.graph.DexItemFactory;
import com.android.tools.r8.graph.DexMethod;
import com.android.tools.r8.graph.DexReference;
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.graph.UseRegistry;
import com.android.tools.r8.ir.conversion.CfSourceCode;
import com.android.tools.r8.ir.conversion.CfState;
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.naming.dexitembasedstring.NameComputationInfo;
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 java.util.ListIterator;
import org.objectweb.asm.MethodVisitor;

public class CfDexItemBasedConstString extends CfInstruction {

  private final DexReference item;
  private final NameComputationInfo<?> nameComputationInfo;

  public CfDexItemBasedConstString(DexReference item, NameComputationInfo<?> nameComputationInfo) {
    this.item = item;
    this.nameComputationInfo = nameComputationInfo;
  }

  @Override
  public int getCompareToId() {
    return CfCompareHelper.CONST_STRING_DEX_ITEM_COMPARE_ID;
  }

  @Override
  public int internalAcceptCompareTo(
      CfInstruction other, CompareToVisitor visitor, CfCompareHelper helper) {
    return visitor.visitDexReference(item, ((CfDexItemBasedConstString) other).item);
  }

  public DexReference getItem() {
    return item;
  }

  public NameComputationInfo<?> getNameComputationInfo() {
    return nameComputationInfo;
  }

  @Override
  public CfDexItemBasedConstString asDexItemBasedConstString() {
    return this;
  }

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

  @Override
  public void write(
      AppView<?> appView,
      ProgramMethod context,
      DexItemFactory dexItemFactory,
      GraphLens graphLens,
      InitClassLens initClassLens,
      NamingLens namingLens,
      LensCodeRewriterUtils rewriter,
      MethodVisitor visitor) {
    throw new Unreachable(
        "CfDexItemBasedConstString instructions should always be rewritten into CfConstString");
  }

  @Override
  public int bytecodeSizeUpperBound() {
    // ldc or ldc_w
    return 3;
  }

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

  @Override
  public boolean canThrow() {
    // const-string* may throw in dex. (Not in CF, see CfSourceCode.canThrowHelper)
    return true;
  }

  @Override
  void internalRegisterUse(
      UseRegistry<?> registry, DexClassAndMethod context, ListIterator<CfInstruction> iterator) {
    if (nameComputationInfo.needsToRegisterReference()) {
      assert item.isDexType();
      registry.registerTypeReference(item.asDexType());
    }
  }

  @Override
  public void buildIR(IRBuilder builder, CfState state, CfSourceCode code) {
    builder.addDexItemBasedConstString(
        state.push(builder.appView.dexItemFactory().stringType).register,
        item,
        nameComputationInfo);
  }

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

  @Override
  public void evaluate(
      CfFrameVerificationHelper frameBuilder,
      DexMethod context,
      AppView<?> appView,
      DexItemFactory dexItemFactory) {
    // ... →
    // ..., value
    frameBuilder.push(dexItemFactory.stringType);
  }

  @Override
  public CfFrameState evaluate(
      CfFrameState frame,
      AppView<?> appView,
      CfAnalysisConfig config,
      DexItemFactory dexItemFactory) {
    // ... →
    // ..., value
    return frame.push(config, dexItemFactory.stringType);
  }
}