Add regression tests for imprecise value propagation

Bug: b/296030319
Change-Id: If699d825bc775d487e2641e67a10b889cd89c9bc
diff --git a/src/test/java/com/android/tools/r8/ir/optimize/callsites/ArgumentPropagationWithInexactUpperBoundTest.java b/src/test/java/com/android/tools/r8/ir/optimize/callsites/ArgumentPropagationWithInexactUpperBoundTest.java
new file mode 100644
index 0000000..71acba4
--- /dev/null
+++ b/src/test/java/com/android/tools/r8/ir/optimize/callsites/ArgumentPropagationWithInexactUpperBoundTest.java
@@ -0,0 +1,168 @@
+// Copyright (c) 2024, 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.callsites;
+
+import static com.android.tools.r8.utils.codeinspector.CodeMatchers.invokesMethod;
+import static com.android.tools.r8.utils.codeinspector.Matchers.isPresent;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import com.android.tools.r8.NeverClassInline;
+import com.android.tools.r8.NeverInline;
+import com.android.tools.r8.NoHorizontalClassMerging;
+import com.android.tools.r8.NoUnusedInterfaceRemoval;
+import com.android.tools.r8.TestBase;
+import com.android.tools.r8.TestParameters;
+import com.android.tools.r8.utils.BooleanUtils;
+import com.android.tools.r8.utils.codeinspector.ClassSubject;
+import com.android.tools.r8.utils.codeinspector.MethodSubject;
+import java.util.List;
+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 ArgumentPropagationWithInexactUpperBoundTest extends TestBase {
+
+  @Parameter(0)
+  public boolean enableDevirtualization;
+
+  @Parameter(1)
+  public TestParameters parameters;
+
+  @Parameters(name = "{1}, devirtualize: {0}")
+  public static List<Object[]> data() {
+    return buildParameters(
+        BooleanUtils.values(), getTestParameters().withAllRuntimesAndApiLevels().build());
+  }
+
+  @Test
+  public void test() throws Exception {
+    testForR8(parameters.getBackend())
+        .addInnerClasses(getClass())
+        .addKeepMainRule(Main.class)
+        .addOptionsModification(options -> options.enableDevirtualization = enableDevirtualization)
+        .enableInliningAnnotations()
+        .enableNeverClassInliningAnnotations()
+        .enableNoHorizontalClassMergingAnnotations()
+        .enableNoUnusedInterfaceRemovalAnnotations()
+        .setMinApi(parameters)
+        .compile()
+        .inspect(
+            inspector -> {
+              ClassSubject iClassSubject = inspector.clazz(I.class);
+              assertThat(iClassSubject, isPresent());
+
+              MethodSubject iMethodSubject = iClassSubject.uniqueMethodWithOriginalName("m");
+              assertThat(iMethodSubject, isPresent());
+
+              ClassSubject aClassSubject = inspector.clazz(A.class);
+              assertThat(aClassSubject, isPresent());
+
+              MethodSubject aMethodSubject = aClassSubject.uniqueMethodWithOriginalName("m");
+              assertThat(aMethodSubject, isPresent());
+              // TODO(b/296030319): Should be true.
+              assertFalse(aMethodSubject.streamInstructions().anyMatch(i -> i.isConstNumber(0)));
+
+              ClassSubject cClassSubject = inspector.clazz(C.class);
+              assertThat(cClassSubject, isPresent());
+
+              MethodSubject cMethodSubject = cClassSubject.uniqueMethodWithOriginalName("m");
+              assertThat(cMethodSubject, isPresent());
+              assertTrue(cMethodSubject.streamInstructions().anyMatch(i -> i.isConstNumber(0)));
+
+              ClassSubject dClassSubject = inspector.clazz(D.class);
+              assertThat(dClassSubject, isPresent());
+
+              MethodSubject dMethodSubject = dClassSubject.uniqueMethodWithOriginalName("m");
+              assertThat(dMethodSubject, isPresent());
+              assertTrue(dMethodSubject.streamInstructions().anyMatch(i -> i.isConstNumber(1)));
+
+              ClassSubject eClassSubject = inspector.clazz(E.class);
+              assertThat(eClassSubject, isPresent());
+
+              MethodSubject eMethodSubject = eClassSubject.uniqueMethodWithOriginalName("m");
+              assertThat(eMethodSubject, isPresent());
+              assertTrue(eMethodSubject.streamInstructions().anyMatch(i -> i.isConstNumber(2)));
+
+              ClassSubject mainClassSubject = inspector.clazz(Main.class);
+              assertThat(mainClassSubject, isPresent());
+
+              // When devirtualization is enabled we could in principle rewrite the call to I.m() to
+              // have symbolic reference A.m.
+              MethodSubject mainMethodSubject = mainClassSubject.mainMethod();
+              assertThat(mainMethodSubject, isPresent());
+              assertThat(mainMethodSubject, invokesMethod(iMethodSubject));
+            })
+        .run(parameters.getRuntime(), Main.class)
+        .assertSuccessWithOutputLines("0", "1", "2");
+  }
+
+  static class Main {
+
+    public static void main(String[] args) {
+      // Call I.m() with upper bound "A{I}".
+      I i = System.currentTimeMillis() > 0 ? new B() : new C();
+      i.m(0);
+
+      // Since D does not implement I, the argument 0 should not be propagated to D.m.
+      new D().m(1);
+
+      // Since E does not extend A, the argument 0 should not be propagated to E.m.
+      new E().m(2);
+    }
+  }
+
+  @NoUnusedInterfaceRemoval
+  interface I {
+
+    void m(int i);
+  }
+
+  abstract static class A {
+
+    public void m(int i) {
+      System.out.println(i);
+    }
+  }
+
+  @NoHorizontalClassMerging
+  static class B extends A implements I {}
+
+  @NoHorizontalClassMerging
+  static class C extends A implements I {
+
+    @Override
+    public void m(int i) {
+      System.out.println(i);
+    }
+  }
+
+  // So that calls to A.m() do not have a single target.
+  @NeverClassInline
+  @NoHorizontalClassMerging
+  static class D extends A {
+
+    @NeverInline
+    @Override
+    public void m(int i) {
+      System.out.println(i);
+    }
+  }
+
+  // So that calls to I.m() do not have a single target.
+  @NeverClassInline
+  @NoHorizontalClassMerging
+  static class E implements I {
+
+    @NeverInline
+    @Override
+    public void m(int i) {
+      System.out.println(i);
+    }
+  }
+}
diff --git a/src/test/java/com/android/tools/r8/ir/optimize/callsites/SiblingInterfaceMethodPropagationWithLowerBoundTest.java b/src/test/java/com/android/tools/r8/ir/optimize/callsites/SiblingInterfaceMethodPropagationWithLowerBoundTest.java
new file mode 100644
index 0000000..2996f59
--- /dev/null
+++ b/src/test/java/com/android/tools/r8/ir/optimize/callsites/SiblingInterfaceMethodPropagationWithLowerBoundTest.java
@@ -0,0 +1,141 @@
+// Copyright (c) 2024, 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.callsites;
+
+import static com.android.tools.r8.utils.codeinspector.Matchers.isPresent;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.Assert.assertFalse;
+
+import com.android.tools.r8.NeverClassInline;
+import com.android.tools.r8.NeverInline;
+import com.android.tools.r8.NoHorizontalClassMerging;
+import com.android.tools.r8.NoUnusedInterfaceRemoval;
+import com.android.tools.r8.NoVerticalClassMerging;
+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.ClassSubject;
+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;
+
+/**
+ * Reproduction of issue found in fastutil where argument information qualified by lower bound type
+ * information is incorrectly propagated to classes below the lower bound in the interface method
+ * argument propagator.
+ */
+@RunWith(Parameterized.class)
+public class SiblingInterfaceMethodPropagationWithLowerBoundTest 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)
+        .enableInliningAnnotations()
+        .enableNeverClassInliningAnnotations()
+        .enableNoHorizontalClassMergingAnnotations()
+        .enableNoUnusedInterfaceRemovalAnnotations()
+        .enableNoVerticalClassMergingAnnotations()
+        .setMinApi(parameters)
+        .compile()
+        .inspect(
+            inspector -> {
+              ClassSubject bClassSubject = inspector.clazz(B.class);
+              assertThat(bClassSubject, isPresent());
+
+              MethodSubject bMethodSubject = bClassSubject.uniqueMethodWithOriginalName("m");
+              assertThat(bMethodSubject, isPresent());
+              // TODO(b/296030319): Should be true.
+              assertFalse(bMethodSubject.streamInstructions().anyMatch(i -> i.isConstNumber(2)));
+            })
+        .run(parameters.getRuntime(), Main.class)
+        .assertSuccess();
+  }
+
+  static class Main {
+
+    public static void main(String[] args) {
+      // To prevent I.m() from being removed by tree shaking.
+      I i = System.currentTimeMillis() > 0 ? new E() : new F();
+      i.m(2);
+      new A().m(1);
+      new C().m(2);
+    }
+  }
+
+  @NoHorizontalClassMerging
+  @NoUnusedInterfaceRemoval
+  @NoVerticalClassMerging
+  interface I {
+
+    void m(int i);
+  }
+
+  @NoHorizontalClassMerging
+  @NoUnusedInterfaceRemoval
+  @NoVerticalClassMerging
+  interface J extends I {}
+
+  @NeverClassInline
+  @NoHorizontalClassMerging
+  @NoVerticalClassMerging
+  static class A implements I {
+
+    @NeverInline
+    @Override
+    public void m(int i) {
+      System.out.println(i);
+    }
+  }
+
+  @NeverClassInline
+  @NoHorizontalClassMerging
+  @NoVerticalClassMerging
+  static class B extends A {
+
+    @NeverInline
+    @Override
+    public void m(int i) {
+      System.out.println(i);
+    }
+  }
+
+  @NeverClassInline
+  @NoVerticalClassMerging
+  static class C extends B implements J {}
+
+  @NeverClassInline
+  @NoHorizontalClassMerging
+  @NoVerticalClassMerging
+  static class E implements I {
+
+    @Override
+    public void m(int i) {
+      System.out.println(i);
+    }
+  }
+
+  @NeverClassInline
+  @NoHorizontalClassMerging
+  @NoVerticalClassMerging
+  static class F implements I {
+
+    @Override
+    public void m(int i) {
+      System.out.println(i);
+    }
+  }
+}
diff --git a/src/test/java/com/android/tools/r8/optimize/argumentpropagation/FieldStateWithCastArgumentPropagationTest.java b/src/test/java/com/android/tools/r8/optimize/argumentpropagation/FieldStateWithCastArgumentPropagationTest.java
new file mode 100644
index 0000000..26f4467
--- /dev/null
+++ b/src/test/java/com/android/tools/r8/optimize/argumentpropagation/FieldStateWithCastArgumentPropagationTest.java
@@ -0,0 +1,85 @@
+// Copyright (c) 2024, 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.optimize.argumentpropagation;
+
+import static com.android.tools.r8.utils.codeinspector.Matchers.isPresent;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.Assert.assertNotEquals;
+
+import com.android.tools.r8.NeverClassInline;
+import com.android.tools.r8.NeverInline;
+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.ClassSubject;
+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 FieldStateWithCastArgumentPropagationTest 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)
+        .enableInliningAnnotations()
+        .enableNeverClassInliningAnnotations()
+        .setMinApi(parameters)
+        .compile()
+        .inspect(
+            inspector -> {
+              ClassSubject mainClassSubject = inspector.clazz(Main.class);
+              assertThat(mainClassSubject, isPresent());
+
+              MethodSubject printMethodSubject =
+                  mainClassSubject.uniqueMethodWithOriginalName("print");
+              assertThat(printMethodSubject, isPresent());
+              // TODO(b/296030319): Should be equals.
+              assertNotEquals("java.lang.String", printMethodSubject.getParameter(0).getTypeName());
+            })
+        .run(parameters.getRuntime(), Main.class)
+        .assertSuccessWithOutputLines("Hello, world!");
+  }
+
+  static class Main {
+
+    public static void main(String[] args) {
+      try {
+        new A(new Object());
+      } catch (ClassCastException e) {
+        System.out.print("Hello");
+      }
+      A a = System.currentTimeMillis() > 0 ? new A(", world!") : new A("unreachable");
+      print(a.f);
+    }
+
+    @NeverInline
+    private static void print(Object o) {
+      System.out.println(o);
+    }
+  }
+
+  @NeverClassInline
+  static class A {
+
+    private Object f;
+
+    A(Object o) {
+      f = (String) o;
+    }
+  }
+}
diff --git a/src/test/java/com/android/tools/r8/optimize/argumentpropagation/FieldWithUnknownDynamicTypeIntoParameterMaybeNullTest.java b/src/test/java/com/android/tools/r8/optimize/argumentpropagation/FieldWithUnknownDynamicTypeIntoParameterMaybeNullTest.java
new file mode 100644
index 0000000..0d4e8d2
--- /dev/null
+++ b/src/test/java/com/android/tools/r8/optimize/argumentpropagation/FieldWithUnknownDynamicTypeIntoParameterMaybeNullTest.java
@@ -0,0 +1,98 @@
+// Copyright (c) 2024, 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.optimize.argumentpropagation;
+
+import static com.android.tools.r8.utils.codeinspector.Matchers.isPresent;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.Assert.assertNotEquals;
+
+import com.android.tools.r8.NeverInline;
+import com.android.tools.r8.NoVerticalClassMerging;
+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.ClassSubject;
+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;
+
+/**
+ * Identical to FieldWithUnknownDynamicTypeIntoParameterTest except that the field {@link Main#f} is
+ * explicitly assigned a nullable value.
+ */
+@RunWith(Parameterized.class)
+public class FieldWithUnknownDynamicTypeIntoParameterMaybeNullTest 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)
+        .enableInliningAnnotations()
+        .enableNoVerticalClassMergingAnnotations()
+        .setMinApi(parameters)
+        .compile()
+        .inspect(
+            inspector -> {
+              ClassSubject aClassSubject = inspector.clazz(A.class);
+              assertThat(aClassSubject, isPresent());
+
+              ClassSubject bClassSubject = inspector.clazz(B.class);
+              assertThat(bClassSubject, isPresent());
+
+              ClassSubject mainClassSubject = inspector.clazz(Main.class);
+              assertThat(mainClassSubject, isPresent());
+
+              MethodSubject testMethodSubject =
+                  mainClassSubject.uniqueMethodWithOriginalName("test");
+              assertThat(testMethodSubject, isPresent());
+              // TODO(b/296030319): Should be equals.
+              assertNotEquals(bClassSubject.asTypeSubject(), testMethodSubject.getParameter(0));
+            })
+        .run(parameters.getRuntime(), Main.class)
+        .assertSuccessWithOutputLines("B");
+  }
+
+  static class Main {
+
+    static B f;
+
+    public static void main(String[] args) {
+      setField();
+      test(f);
+    }
+
+    @NeverInline
+    static void setField() {
+      f = System.currentTimeMillis() > 0 ? new B() : null;
+    }
+
+    @NeverInline
+    static void test(A a) {
+      System.out.println(a);
+    }
+  }
+
+  @NoVerticalClassMerging
+  static class A {}
+
+  static class B extends A {
+
+    @Override
+    public String toString() {
+      return "B";
+    }
+  }
+}
diff --git a/src/test/java/com/android/tools/r8/optimize/argumentpropagation/FieldWithUnknownDynamicTypeIntoParameterTest.java b/src/test/java/com/android/tools/r8/optimize/argumentpropagation/FieldWithUnknownDynamicTypeIntoParameterTest.java
new file mode 100644
index 0000000..0298201
--- /dev/null
+++ b/src/test/java/com/android/tools/r8/optimize/argumentpropagation/FieldWithUnknownDynamicTypeIntoParameterTest.java
@@ -0,0 +1,94 @@
+// Copyright (c) 2024, 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.optimize.argumentpropagation;
+
+import static com.android.tools.r8.utils.codeinspector.Matchers.isPresent;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.Assert.assertNotEquals;
+
+import com.android.tools.r8.NeverInline;
+import com.android.tools.r8.NoVerticalClassMerging;
+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.ClassSubject;
+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 FieldWithUnknownDynamicTypeIntoParameterTest 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)
+        .enableInliningAnnotations()
+        .enableNoVerticalClassMergingAnnotations()
+        .setMinApi(parameters)
+        .compile()
+        .inspect(
+            inspector -> {
+              ClassSubject aClassSubject = inspector.clazz(A.class);
+              assertThat(aClassSubject, isPresent());
+
+              ClassSubject bClassSubject = inspector.clazz(B.class);
+              assertThat(bClassSubject, isPresent());
+
+              ClassSubject mainClassSubject = inspector.clazz(Main.class);
+              assertThat(mainClassSubject, isPresent());
+
+              MethodSubject testMethodSubject =
+                  mainClassSubject.uniqueMethodWithOriginalName("test");
+              assertThat(testMethodSubject, isPresent());
+              // TODO(b/296030319): Should be equals.
+              assertNotEquals(bClassSubject.asTypeSubject(), testMethodSubject.getParameter(0));
+            })
+        .run(parameters.getRuntime(), Main.class)
+        .assertSuccessWithOutputLines("B");
+  }
+
+  static class Main {
+
+    static B f;
+
+    public static void main(String[] args) {
+      setField();
+      test(f);
+    }
+
+    @NeverInline
+    static void setField() {
+      f = new B();
+    }
+
+    @NeverInline
+    static void test(A a) {
+      System.out.println(a);
+    }
+  }
+
+  @NoVerticalClassMerging
+  static class A {}
+
+  static class B extends A {
+
+    @Override
+    public String toString() {
+      return "B";
+    }
+  }
+}
diff --git a/src/test/java/com/android/tools/r8/optimize/argumentpropagation/ParameterWithUnknownDynamicTypeIntoFieldTest.java b/src/test/java/com/android/tools/r8/optimize/argumentpropagation/ParameterWithUnknownDynamicTypeIntoFieldTest.java
new file mode 100644
index 0000000..eb9e6ad
--- /dev/null
+++ b/src/test/java/com/android/tools/r8/optimize/argumentpropagation/ParameterWithUnknownDynamicTypeIntoFieldTest.java
@@ -0,0 +1,130 @@
+// Copyright (c) 2024, 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.optimize.argumentpropagation;
+
+import static com.android.tools.r8.utils.codeinspector.Matchers.isPresent;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+
+import com.android.tools.r8.NeverInline;
+import com.android.tools.r8.NoVerticalClassMerging;
+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.ClassSubject;
+import com.android.tools.r8.utils.codeinspector.FieldSubject;
+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 ParameterWithUnknownDynamicTypeIntoFieldTest 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)
+        .enableInliningAnnotations()
+        .enableNoVerticalClassMergingAnnotations()
+        .setMinApi(parameters)
+        .compile()
+        .inspect(
+            inspector -> {
+              ClassSubject aClassSubject = inspector.clazz(A.class);
+              assertThat(aClassSubject, isPresent());
+
+              ClassSubject bClassSubject = inspector.clazz(B.class);
+              assertThat(bClassSubject, isPresent());
+
+              ClassSubject cClassSubject = inspector.clazz(C.class);
+              assertThat(cClassSubject, isPresent());
+
+              ClassSubject mainClassSubject = inspector.clazz(Main.class);
+              assertThat(mainClassSubject, isPresent());
+
+              // Verify that we have strengthened the type of field fieldWithNullableB to type B.
+              FieldSubject fieldWithNullableBSubject =
+                  mainClassSubject.uniqueFieldWithOriginalName("fieldWithNullableB");
+              assertThat(fieldWithNullableBSubject, isPresent());
+              assertEquals(bClassSubject.asTypeSubject(), fieldWithNullableBSubject.getType());
+
+              // Verify that we have strengthened the type of field fieldWithNullableC to type C.
+              FieldSubject fieldWithNullableCSubject =
+                  mainClassSubject.uniqueFieldWithOriginalName("fieldWithNullableC");
+              assertThat(fieldWithNullableCSubject, isPresent());
+              // TODO(b/296030319): Should be C.
+              assertNotEquals(aClassSubject.asTypeSubject(), fieldWithNullableCSubject.getType());
+            })
+        .run(parameters.getRuntime(), Main.class)
+        .assertSuccessWithOutputLines("B", "C");
+  }
+
+  static class Main {
+
+    static A fieldWithNullableB;
+    static A fieldWithNullableC;
+
+    public static void main(String[] args) {
+      B nullableB = System.currentTimeMillis() > 0 ? new B() : null;
+      setFieldWithNullableB(nullableB);
+      getFieldWithNullableB();
+
+      B nullableC = System.currentTimeMillis() > 0 ? new C() : null;
+      setFieldWithNullableC(nullableC);
+      getFieldWithNullableC();
+    }
+
+    @NeverInline
+    static void setFieldWithNullableB(B b) {
+      fieldWithNullableB = b;
+    }
+
+    @NeverInline
+    static void setFieldWithNullableC(B b) {
+      fieldWithNullableC = b;
+    }
+
+    @NeverInline
+    static void getFieldWithNullableB() {
+      System.out.println(fieldWithNullableB);
+    }
+
+    @NeverInline
+    static void getFieldWithNullableC() {
+      System.out.println(fieldWithNullableC);
+    }
+  }
+
+  @NoVerticalClassMerging
+  static class A {}
+
+  @NoVerticalClassMerging
+  static class B extends A {
+
+    @Override
+    public String toString() {
+      return "B";
+    }
+  }
+
+  static class C extends B {
+
+    @Override
+    public String toString() {
+      return "C";
+    }
+  }
+}
diff --git a/src/test/testbase/java/com/android/tools/r8/utils/codeinspector/AbsentFieldSubject.java b/src/test/testbase/java/com/android/tools/r8/utils/codeinspector/AbsentFieldSubject.java
index 6eeab19..616e4d5 100644
--- a/src/test/testbase/java/com/android/tools/r8/utils/codeinspector/AbsentFieldSubject.java
+++ b/src/test/testbase/java/com/android/tools/r8/utils/codeinspector/AbsentFieldSubject.java
@@ -50,6 +50,11 @@
   }
 
   @Override
+  public TypeSubject getType() {
+    throw new Unreachable("Cannot get the type of an absent field");
+  }
+
+  @Override
   public String getOriginalSignatureAttribute() {
     return null;
   }
diff --git a/src/test/testbase/java/com/android/tools/r8/utils/codeinspector/FieldSubject.java b/src/test/testbase/java/com/android/tools/r8/utils/codeinspector/FieldSubject.java
index 04a5c9c..3c3f9b7 100644
--- a/src/test/testbase/java/com/android/tools/r8/utils/codeinspector/FieldSubject.java
+++ b/src/test/testbase/java/com/android/tools/r8/utils/codeinspector/FieldSubject.java
@@ -19,6 +19,8 @@
     return getField().getReference();
   }
 
+  public abstract TypeSubject getType();
+
   public abstract DexValue getStaticValue();
 
   @Override
diff --git a/src/test/testbase/java/com/android/tools/r8/utils/codeinspector/FoundFieldSubject.java b/src/test/testbase/java/com/android/tools/r8/utils/codeinspector/FoundFieldSubject.java
index 45944b2..70646cd 100644
--- a/src/test/testbase/java/com/android/tools/r8/utils/codeinspector/FoundFieldSubject.java
+++ b/src/test/testbase/java/com/android/tools/r8/utils/codeinspector/FoundFieldSubject.java
@@ -109,6 +109,11 @@
   }
 
   @Override
+  public TypeSubject getType() {
+    return new TypeSubject(codeInspector, dexField.getType());
+  }
+
+  @Override
   public String getOriginalSignatureAttribute() {
     return codeInspector.getOriginalSignatureAttribute(
         getFinalSignatureAttribute(), GenericSignatureParser::parseFieldSignature);