Automatic merge of jdk:master into master

src/hotspot/share/opto/loopTransform.cpp

@@ -1480,14 +1480,14 @@ void PhaseIdealLoop::insert_pre_post_loops(IdealLoopTree *loop, Node_List &old_n
   Node_Stack clones(main_head->back_control()->outcnt());
   // Step B3: Make the fall-in values to the main-loop come from the
   // fall-out values of the pre-loop.
-  for (DUIterator_Fast i2max, i2 = main_head->fast_outs(i2max); i2 < i2max; i2++) {
-    Node* main_phi = main_head->fast_out(i2);
+  for (DUIterator i2 = main_head->outs(); main_head->has_out(i2); i2++) {
+    Node* main_phi = main_head->out(i2);
     if (main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() > 0) {
-      Node *pre_phi = old_new[main_phi->_idx];
-      Node *fallpre  = clone_up_backedge_goo(pre_head->back_control(),
-                                             main_head->skip_strip_mined()->in(LoopNode::EntryControl),
-                                             pre_phi->in(LoopNode::LoopBackControl),
-                                             visited, clones);
+      Node* pre_phi = old_new[main_phi->_idx];
+      Node* fallpre = clone_up_backedge_goo(pre_head->back_control(),
+                                            main_head->skip_strip_mined()->in(LoopNode::EntryControl),
+                                            pre_phi->in(LoopNode::LoopBackControl),
+                                            visited, clones);
       _igvn.hash_delete(main_phi);
       main_phi->set_req(LoopNode::EntryControl, fallpre);
     }
@@ -1765,11 +1765,11 @@ Node *PhaseIdealLoop::insert_post_loop(IdealLoopTree *loop, Node_List &old_new,
   Node_Stack clones(main_head->back_control()->outcnt());
   // Step A3: Make the fall-in values to the post-loop come from the
   // fall-out values of the main-loop.
-  for (DUIterator_Fast imax, i = main_head->fast_outs(imax); i < imax; i++) {
-    Node* main_phi = main_head->fast_out(i);
+  for (DUIterator i = main_head->outs(); main_head->has_out(i); i++) {
+    Node* main_phi = main_head->out(i);
     if (main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() > 0) {
-      Node *cur_phi = old_new[main_phi->_idx];
-      Node *fallnew = clone_up_backedge_goo(main_head->back_control(),
+      Node* cur_phi = old_new[main_phi->_idx];
+      Node* fallnew = clone_up_backedge_goo(main_head->back_control(),
                                             post_head->init_control(),
                                             main_phi->in(LoopNode::LoopBackControl),
                                             visited, clones);

test/hotspot/jtreg/compiler/loopopts/TestPreMainPostFallInEdges.java

@@ -0,0 +1,93 @@
+/*
+ * Copyright (c) 2020, 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.
+ */
+
+/*
+ * @test
+ * @bug 8249602
+ * @summary Tests the rewiring and cloning of fall-in values from the main loop (and pre loop) to the post (and main loop)
+ *          which resulted in a DUIterator_Fast assertion failure due to an insertion in the outputs of the loop header node.
+ *
+ * @run main compiler.loopopts.TestPreMainPostFallInEdges
+ */
+
+package compiler.loopopts;
+
+public class TestPreMainPostFallInEdges {
+
+    public static int test() {
+        int iArr[] = new int[400];
+        float fArr[] = new float[400];
+        int x = 0;
+        byte y = 124;
+        short z = 0;
+
+        int i = 1;
+        do {
+            int j = 1;
+            do {
+                z *= 11;
+
+                // These 4 array stores live in the back control block and cannot float. They are cloned and their control input set to the preheader control
+                // block of the post loop. If their input edges also have their placement in the back control block (get_ctrl == back control) then they are
+                // cloned as well. The following code hits the assertion failure when we clone a node with a control edge to the loop header block of the main.
+                // loop. The DUIterator_Fast does not allow insertions. The fix is to replace it by a normal DUIterator which allows insertions.
+                iArr[j] = 3;
+                // load of iArr[j + 1] is also cloned but has a control edge to the main loop header block hitting the assertion failure.
+                iArr[j + 1] += 4;
+                fArr[j] = 5;
+                fArr[j + 1] += fArr[j + 5]; // same for load of fArr[j + 1] and load of fArr[j + 5]
+
+                int k = 1;
+                do {
+                    iArr[j] *= 324;
+                    x = 34;
+                    y *= 54;
+                } while (k < 1);
+            } while (++j < 6);
+        } while (++i < 289);
+        return checkSum(iArr) + checkSum(fArr);
+    }
+
+    public static int checkSum(int[] a) {
+        int sum = 0;
+        for (int j = 0; j < a.length; j++) {
+            sum += a[j] % (j + 1);
+        }
+        return sum;
+    }
+
+    public static int checkSum(float[] a) {
+        int sum = 0;
+        for (int j = 0; j < a.length; j++) {
+            sum += a[j] % (j + 1);
+        }
+        return sum;
+    }
+
+    public static void main(String[] strArr) {
+        for (int i = 0; i < 10000; i++) {
+            test();
+        }
+    }
+}
+