--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.replacements.test/src/org/graalvm/compiler/replacements/test/StringSubstitutionsTest.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2014, 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.graalvm.compiler.replacements.test;
+
+import org.junit.Test;
+
+import org.graalvm.compiler.nodes.StructuredGraph;
+import org.graalvm.compiler.replacements.StringSubstitutions;
+import org.graalvm.compiler.replacements.nodes.ArrayEqualsNode;
+
+import jdk.vm.ci.code.InstalledCode;
+import jdk.vm.ci.meta.ResolvedJavaMethod;
+
+/**
+ * Tests {@link StringSubstitutions}.
+ */
+public class StringSubstitutionsTest extends MethodSubstitutionTest {
+
+    public void testSubstitution(String testMethodName, Class<?> intrinsicClass, Class<?> holder, String methodName, boolean optional, Object[] args1, Object[] args2) {
+        ResolvedJavaMethod realMethod = getResolvedJavaMethod(holder, methodName);
+        ResolvedJavaMethod testMethod = getResolvedJavaMethod(testMethodName);
+        StructuredGraph graph = testGraph(testMethodName);
+
+        // Check to see if the resulting graph contains the expected node
+        StructuredGraph replacement = getReplacements().getSubstitution(realMethod, -1);
+        if (replacement == null && !optional) {
+            assertInGraph(graph, intrinsicClass);
+        }
+
+        // Force compilation
+        InstalledCode code = getCode(testMethod);
+        assert optional || code != null;
+
+        for (int i = 0; i < args1.length; i++) {
+            Object arg1 = args1[i];
+            Object arg2 = args2[i];
+            Object expected = invokeSafe(realMethod, arg1, arg2);
+            // Verify that the original method and the substitution produce the same value
+            assertDeepEquals(expected, invokeSafe(testMethod, null, arg1, arg2));
+            // Verify that the generated code and the original produce the same value
+            assertDeepEquals(expected, executeVarargsSafe(code, arg1, arg2));
+        }
+    }
+
+    @Test
+    public void testEquals() {
+        if (!Java8OrEarlier) {
+            // StringSubstitutions are disabled in 1.9
+            return;
+        }
+
+        final int n = 1000;
+        Object[] args1 = new Object[n];
+        Object[] args2 = new Object[n];
+
+        // equal strings
+        String s1 = "";
+        String s2 = "";
+        for (int i = 0; i < n / 2; i++) {
+            args1[i] = s1;
+            args2[i] = s2;
+            s1 = s1 + "0";
+            s2 = s2 + "0";
+        }
+
+        // non-equal strings
+        s1 = "";
+        s2 = "";
+        for (int i = n / 2; i < n; i++) {
+            args1[i] = s1;
+            args2[i] = s2;
+            s2 = s1 + "1";
+            s1 = s1 + "0";
+        }
+
+        testSubstitution("stringEquals", ArrayEqualsNode.class, String.class, "equals", false, args1, args2);
+    }
+
+    @SuppressWarnings("all")
+    public static boolean stringEquals(String a, String b) {
+        return a.equals(b);
+    }
+
+}