8236759: ShouldNotReachHere in PhaseIdealLoop::verify_strip_mined_sch…

…eduling

Reviewed-by: thartmann, neliasso

src/hotspot/share/opto/memnode.cpp

@@ -1483,14 +1483,20 @@ Node *LoadNode::split_through_phi(PhaseGVN *phase) {
   for (uint i = 1; i < region->req(); i++) {
     Node* x;
     Node* the_clone = NULL;
-    if (region->in(i) == C->top()) {
+    Node* in = region->in(i);
+    if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
+        in != NULL && in->is_OuterStripMinedLoop()) {
+      // No node should go in the outer strip mined loop
+      in = in->in(LoopNode::EntryControl);
+    }
+    if (in == NULL || in == C->top()) {
       x = C->top();      // Dead path?  Use a dead data op
     } else {
       x = this->clone();        // Else clone up the data op
       the_clone = x;            // Remember for possible deletion.
       // Alter data node to use pre-phi inputs
       if (this->in(0) == region) {
-        x->set_req(0, region->in(i));
+        x->set_req(0, in);
       } else {
         x->set_req(0, NULL);
       }

test/hotspot/jtreg/compiler/loopstripmining/LoadSplitThruPhi.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2020, Red Hat, 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 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 8236759
+ * @summary ShouldNotReachHere in PhaseIdealLoop::verify_strip_mined_scheduling
+ * @requires vm.compiler2.enabled
+ *
+ * @run main/othervm LoadSplitThruPhi
+ *
+ */
+
+public class LoadSplitThruPhi {
+
+    public static void getPermutations(byte[] inputArray, byte[][] outputArray) {
+        int[] indexes = new int[]{0, 2};
+
+        for (int a = 0; a < inputArray.length; a++) {
+            int oneIdx = indexes[0]++;
+            for (int b = a + 1; b < inputArray.length; b++) {
+                int twoIdx = indexes[1]++;
+                outputArray[twoIdx][0] = inputArray[a];
+                outputArray[twoIdx][1] = inputArray[b];
+            }
+        }
+    }
+
+    public static void main(String[] args) {
+
+        final byte[] inputArray = new byte[]{0, 1};
+        final byte[][] outputArray = new byte[3][2];
+
+        for (int i = 0; i < 1000000; i++) {
+            getPermutations(inputArray, outputArray);
+        }
+    }
+
+}