src/test/java/com/android/tools/r8/ir/optimize/string/StringBuilderWithIndirectMutationThroughNewInstanceTest.java

// Copyright (c) 2022, 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.optimize.string;

import static com.android.tools.r8.ir.optimize.string.utils.StringBuilderCodeMatchers.isInvokeStringBuilderAppendWithString;
import static org.junit.Assert.assertEquals;

import com.android.tools.r8.ReprocessMethod;
import com.android.tools.r8.TestBase;
import com.android.tools.r8.TestParameters;
import com.android.tools.r8.TestParametersCollection;
import com.android.tools.r8.utils.codeinspector.MethodSubject;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameter;
import org.junit.runners.Parameterized.Parameters;

@RunWith(Parameterized.class)
public class StringBuilderWithIndirectMutationThroughNewInstanceTest extends TestBase {

  @Parameter(0)
  public TestParameters parameters;

  @Parameters(name = "{0}")
  public static TestParametersCollection data() {
    return getTestParameters().withAllRuntimesAndApiLevels().build();
  }

  @Test
  public void test() throws Exception {
    testForR8(parameters.getBackend())
        .addInnerClasses(getClass())
        .addKeepMainRule(Main.class)
        .enableReprocessMethodAnnotations()
        .setMinApi(parameters.getApiLevel())
        .compile()
        .inspect(
            inspector -> {
              MethodSubject mainMethodSubject = inspector.clazz(Main.class).mainMethod();
              assertEquals(
                  2,
                  mainMethodSubject
                      .streamInstructions()
                      .filter(isInvokeStringBuilderAppendWithString())
                      .count());
            })
        .run(parameters.getRuntime(), Main.class)
        .assertSuccessWithOutputLines("foobarbaz");
  }

  static class Main {

    static StringBuilder escape;

    // Reprocess method to ensure call to A.<init> is removed by dead code elimination before
    // running StringBuilder optimization.
    @ReprocessMethod
    public static void main(String[] args) {
      StringBuilder sb = new StringBuilder();
      escape = sb;
      sb.append("foo");
      new A();
      sb.append("baz");
      System.out.println(sb.toString());
    }
  }

  static class A {

    static {
      Main.escape.append("bar");
    }
  }
}