8371319: java.lang.reflect.Method#equals doesn't short-circuit with same instances

src/java.base/share/classes/java/lang/reflect/Executable.java

@@ -70,6 +70,10 @@ public abstract sealed class Executable extends AccessibleObject
     abstract ConstructorRepository getGenericInfo();
 
     boolean equalParamTypes(Class<?>[] params1, Class<?>[] params2) {
+        // The parameter arrays are trusted and the same for a root and all leaf
+        // copies. Thus, == on arrays is more useful than == on Executable.
+        if (params1 == params2)
+            return true;
         /* Avoid unnecessary cloning */
         if (params1.length == params2.length) {
             for (int i = 0; i < params1.length; i++) {

test/micro/org/openjdk/bench/java/lang/reflect/ExecutableCompareBenchmark.java

@@ -0,0 +1,84 @@
+/*
+ * 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.
+ */
+package org.openjdk.bench.java.lang.reflect;
+
+import java.lang.reflect.Method;
+import java.util.concurrent.TimeUnit;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+
+/**
+ * Benchmark measuring the speed of Method and Constructor comparison.
+ */
+@BenchmarkMode(Mode.AverageTime)
+@State(Scope.Benchmark)
+@OutputTimeUnit(TimeUnit.NANOSECONDS)
+@Fork(1)
+@Warmup(iterations = 3, time = 2, timeUnit = TimeUnit.SECONDS)
+@Measurement(iterations = 5, time = 2, timeUnit = TimeUnit.SECONDS)
+public class ExecutableCompareBenchmark {
+    Method appendRange;
+    Method appendRangeDup;
+    Method appendFull;
+
+    public ExecutableCompareBenchmark() {
+        try {
+            appendRange = Appendable.class.getMethod("append", CharSequence.class, int.class, int.class);
+            appendRangeDup = Appendable.class.getMethod("append", CharSequence.class, int.class, int.class);
+            if (appendRange == appendRangeDup || !appendRange.equals(appendRangeDup)) {
+                throw new IllegalStateException();
+            }
+            appendFull = Appendable.class.getMethod("append", CharSequence.class);
+        } catch (ReflectiveOperationException ex) {
+            throw new RuntimeException(ex);
+        }
+    }
+
+    // Comparing identical Method objects.
+    @Benchmark
+    public boolean sameMethodObject() {
+        return appendRange.equals(appendRange);
+    }
+
+    // Comparing equal Method objects with potentially different access
+    // suppression status.
+    @Benchmark
+    public boolean equalMethods() {
+        return appendRange.equals(appendRangeDup);
+    }
+
+    // Comparing Method objects with only different parameter types;
+    // The declaring class, name, and the return type are the same.
+    @Benchmark
+    public boolean distinctParams() {
+        return appendRange.equals(appendFull);
+    }
+}