6935535: String.indexOf() returns incorrect result on x86 with SSE4.2

Summary: Added missing counter decrement when substring search restarted.
Reviewed-by: twisti

src/cpu/x86/vm/assembler_x86.cpp

@@ -8460,6 +8460,7 @@ void MacroAssembler::string_indexof(Register str1, Register str2,
   subptr(str1, result); // Restore counter
   shrl(str1, 1);
   addl(cnt1, str1);
+  decrementl(cnt1);
   lea(str1, Address(result, 2)); // Reload string
 
   // Load substr

test/compiler/6935535/Test.java

+/*
+ * Copyright 2010 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/**
+ * @test
+ * @bug 6935535
+ * @summary String.indexOf() returns incorrect result on x86 with SSE4.2
+ *
+ * @run main/othervm -Xcomp Test
+ */
+
+public class Test {
+
+  static int IndexOfTest(String str) {
+    return str.indexOf("1111111111111xx1x");
+  }
+
+  public static void main(String args[]) {
+    String str = "1111111111111xx1111111111111xx1x";
+    str = str.substring(0, 31);
+    int idx = IndexOfTest(str);
+    System.out.println("IndexOf(" + "1111111111111xx1x" + ") = " + idx + " in " + str);
+    if (idx != -1) {
+      System.exit(97);
+    }
+  }
+}
+