Add test for improved InstanceOfNode canonicalization

compiler/src/jdk.graal.compiler.test/src/jdk/graal/compiler/core/test/InstanceOfCanonicalizationTest.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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+ */
+package jdk.graal.compiler.core.test;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import jdk.graal.compiler.nodes.StructuredGraph;
+import jdk.graal.compiler.nodes.StructuredGraph.AllowAssumptions;
+import jdk.graal.compiler.nodes.calc.IsNullNode;
+import jdk.graal.compiler.nodes.java.InstanceOfNode;
+
+public class InstanceOfCanonicalizationTest extends GraalCompilerTest {
+
+    public static boolean checkCastIncompatibleTypes(Object arr) {
+        // Cast first to a byte array, then to a boolean array. This only succeeds if arr is null.
+        byte[] barr = (byte[]) arr;
+        boolean[] bbarr = (boolean[]) (Object) barr;
+        return true;
+    }
+
+    public static int unsatisfiableInstanceOf(byte[] barr) {
+        // Plain instanceof does not allow null, so this will never succeed.
+        if ((Object) barr instanceof boolean[]) {
+            return -1;
+        }
+        return 1;
+    }
+
+    @Test
+    public void testCheckCastIncompatibleTypes() {
+        StructuredGraph g = parseEager("checkCastIncompatibleTypes", AllowAssumptions.NO, getInitialOptions());
+        createCanonicalizerPhase().apply(g, getDefaultHighTierContext());
+
+        // The second check-cast against boolean[] should canonicalize to a null check
+        Assert.assertEquals(1, g.getNodes().filter(InstanceOfNode.class).count());
+        Assert.assertEquals(1, g.getNodes().filter(IsNullNode.class).count());
+
+        testAgainstExpected(g.method(), new Result(checkCastIncompatibleTypes(null), null), null, new Object[]{null});
+        testAgainstExpected(g.method(), new Result(null, new ClassCastException()), null, new Object[]{new byte[10]});
+        testAgainstExpected(g.method(), new Result(null, new ClassCastException()), null, new Object[]{new boolean[10]});
+    }
+
+    @Test
+    public void testUnsatisfiableInstanceOf() {
+        StructuredGraph g = parseEager("unsatisfiableInstanceOf", AllowAssumptions.NO, getInitialOptions());
+        createCanonicalizerPhase().apply(g, getDefaultHighTierContext());
+
+        // Tested condition can never be true, so it should canonicalize to a constant.
+        Assert.assertEquals(0, g.getNodes().filter(InstanceOfNode.class).count());
+
+        testAgainstExpected(g.method(), new Result(unsatisfiableInstanceOf(null), null), null, new Object[]{null});
+        testAgainstExpected(g.method(), new Result(unsatisfiableInstanceOf(new byte[10]), null), null, new Object[]{new byte[10]});
+    }
+}