--- old/src/hotspot/share/opto/loopTransform.cpp	2019-08-21 16:33:55.327800773 +0800
+++ new/src/hotspot/share/opto/loopTransform.cpp	2019-08-21 16:33:55.215798859 +0800
@@ -831,6 +831,15 @@
     return false;
   }
 
+  // Protect against over-unrolling with SuperWordLoopUnrollAnalysis.
+  if (SuperWordLoopUnrollAnalysis &&
+      !cl->is_vectorized_loop() &&
+      future_unroll_cnt > LoopUnrollMin &&
+      cl->profile_trip_cnt() != COUNT_UNKNOWN &&
+      (uint)(2 * cl->unrolled_count()) > cl->trip_count()) {
+    return false;
+  }
+
   Node *init_n = cl->init_trip();
   Node *limit_n = cl->limit();
   int stride_con = cl->stride_con();
--- /dev/null	2019-08-21 16:04:56.746381791 +0800
+++ new/test/hotspot/jtreg/compiler/loopopts/superword/RunTestSuperWordOverunrolling.java	2019-08-21 16:33:55.487803508 +0800
@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2019, Loongson Technology Co. Ltd. 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 8227505
+ * @summary SuperWordLoopUnrollAnalysis may over unrolling
+ * @library /test/lib
+ * @compile TestSuperWordOverunrolling.java
+ * @run main/othervm compiler.loopopts.superword.RunTestSuperWordOverunrolling
+ *
+ */
+
+package compiler.loopopts.superword;
+
+import jdk.test.lib.process.OutputAnalyzer;
+import jdk.test.lib.process.ProcessTools;
+
+public class RunTestSuperWordOverunrolling {
+
+    public static void main(String[] args) throws Exception {
+        test();
+    }
+
+    private static void test() throws Exception {
+        ProcessBuilder pb;
+        OutputAnalyzer analyzer;
+        pb = ProcessTools.createJavaProcessBuilder("-XX:+IgnoreUnrecognizedVMOptions",
+                                                   "-Xbatch",
+                                                   "-XX:+TraceLoopOpts",
+                                                   "-XX:-TieredCompilation",
+                                                   "-XX:CompileCommand=quiet",
+                                                   "-XX:CompileOnly=compiler.loopopts.superword.TestSuperWordOverunrolling::execute",
+                                                   "compiler.loopopts.superword.TestSuperWordOverunrolling");
+        analyzer = new OutputAnalyzer(pb.start());
+        analyzer.shouldNotContain("Unroll 16");
+    }
+}
--- /dev/null	2019-08-21 16:04:56.746381791 +0800
+++ new/test/hotspot/jtreg/compiler/loopopts/superword/TestSuperWordOverunrolling.java	2019-08-21 16:33:55.771808362 +0800
@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2019, Loongson Technology Co. Ltd. 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 compiler.loopopts.superword;
+
+public class TestSuperWordOverunrolling {
+    public static void main(String[] args) {
+        double sum = 0.0;
+        long start = System.currentTimeMillis();
+        for (int i = 0; i < 5; i++) {
+            sum += execute(128);
+        }
+        long end = System.currentTimeMillis();
+        System.out.println("sum = " + sum + "; time = " + (end - start) + "ms");
+    }
+
+    public static double execute(int num_iterations) {
+        int M = 63;
+        byte[][] G = new byte[M][M];
+
+        int Mm1 = M-1;
+        for (int p = 0; p < num_iterations; p++) {
+            for (int i = 1; i < Mm1; i++) {
+                for (int j = 1; j < Mm1; j++)
+                    G[i][j] = G[i-1][j];
+            }
+        }
+
+        return G[3][2];
+    }
+}