Test from Jorn

test/jdk/java/lang/invoke/VarHandles/PolymorphicCallSiteInlineTest.java

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+/*
+ * Copyright (c) 2025, 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.
+ *
+ * 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8160821
+ * @summary Ensures a polymorphic call site with non-exact invocation won't
+ *          be incorrectly inlined/optimized
+ * @requires vm.compiler2.enabled
+ * @run main/othervm -XX:CompileCommand=PrintCompilation,Main::*
+ *                   -XX:CompileCommand=dontinline,Main::payload*
+ *                   -Xbatch
+ *                   PolymorphicCallSiteInlineTest
+ */
+
+import java.lang.invoke.*;
+import java.util.concurrent.CountDownLatch;
+
+public class PolymorphicCallSiteInlineTest {
+
+    // C2 should inline m into payload1/payload2 in this many runs
+    static final int RUNS = 0x10000;
+
+    static final int X = 0;
+    static final long Y = 0L;
+
+    static final VarHandle VH_X;
+    static final VarHandle VH_Y;
+
+    static {
+        try {
+            var lookup = MethodHandles.lookup();
+            VH_X = lookup.findStaticVarHandle(PolymorphicCallSiteInlineTest.class, "X", int.class);
+            VH_Y = lookup.findStaticVarHandle(PolymorphicCallSiteInlineTest.class, "Y", long.class);
+        } catch (ReflectiveOperationException e) {
+            throw new ExceptionInInitializerError(e);
+        }
+    };
+
+    public static void main(String[] args) {
+
+        CountDownLatch latch = new CountDownLatch(2);
+
+        Thread.ofPlatform().start(() -> {
+            latch.countDown();
+            try {
+                latch.await();
+            } catch (InterruptedException ex) {
+                throw new RuntimeException(ex);
+            }
+            System.out.println("T1 running");
+            for (int i = 0; i < RUNS; i++) {
+                payload1();
+            }
+        });
+
+        Thread.ofPlatform().start(() -> {
+            latch.countDown();
+            try {
+                latch.await();
+            } catch (InterruptedException ex) {
+                throw new RuntimeException(ex);
+            }
+            System.out.println("T2 running");
+            for (int i = 0; i < RUNS; i++) {
+                payload2();
+            }
+        });
+    }
+
+    public static int payload1() {
+        return (int) m(VH_X);
+    }
+
+    public static long payload2() {
+        return (long) m(VH_Y);
+    }
+
+    public static Object m(VarHandle vh) {
+        // This is a polymorphic site that sees many VarHandle, but each VH
+        // is considered "constant" when inlined into payload1/payload2
+        // payload1/payload2 will throw exceptions if the incorrect VH gets inlined
+        return vh.get();
+    }
+}