8295788: C2 compilation hits "assert((mode == ControlAroundStripMined && use == sfpt) || !use->is_reachable_from_root()) failed: missed a node"

Backport-of: 761a4f4852cbb40660b6fb9eda4d740464218f75

Author: GoeLin

src/hotspot/share/opto/loopopts.cpp

@@ -2041,26 +2041,28 @@ void PhaseIdealLoop::clone_loop_handle_data_uses(Node* old, Node_List &old_new,
   }
 }
 
-static void clone_outer_loop_helper(Node* n, const IdealLoopTree *loop, const IdealLoopTree* outer_loop,
-                                    const Node_List &old_new, Unique_Node_List& wq, PhaseIdealLoop* phase,
-                                    bool check_old_new) {
+static void collect_nodes_in_outer_loop_not_reachable_from_sfpt(Node* n, const IdealLoopTree *loop, const IdealLoopTree* outer_loop,
+                                                                const Node_List &old_new, Unique_Node_List& wq, PhaseIdealLoop* phase,
+                                                                bool check_old_new) {
   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
     Node* u = n->fast_out(j);
     assert(check_old_new || old_new[u->_idx] == NULL, "shouldn't have been cloned");
     if (!u->is_CFG() && (!check_old_new || old_new[u->_idx] == NULL)) {
       Node* c = phase->get_ctrl(u);
       IdealLoopTree* u_loop = phase->get_loop(c);
-      assert(!loop->is_member(u_loop), "can be in outer loop or out of both loops only");
-      if (outer_loop->is_member(u_loop)) {
-        wq.push(u);
-      } else {
-        // nodes pinned with control in the outer loop but not referenced from the safepoint must be moved out of
-        // the outer loop too
-        Node* u_c = u->in(0);
-        if (u_c != NULL) {
-          IdealLoopTree* u_c_loop = phase->get_loop(u_c);
-          if (outer_loop->is_member(u_c_loop) && !loop->is_member(u_c_loop)) {
-            wq.push(u);
+      assert(!loop->is_member(u_loop) || !loop->_body.contains(u), "can be in outer loop or out of both loops only");
+      if (!loop->is_member(u_loop)) {
+        if (outer_loop->is_member(u_loop)) {
+          wq.push(u);
+        } else {
+          // nodes pinned with control in the outer loop but not referenced from the safepoint must be moved out of
+          // the outer loop too
+          Node* u_c = u->in(0);
+          if (u_c != NULL) {
+            IdealLoopTree* u_c_loop = phase->get_loop(u_c);
+            if (outer_loop->is_member(u_c_loop) && !loop->is_member(u_c_loop)) {
+              wq.push(u);
+            }
           }
         }
       }
@@ -2179,12 +2181,17 @@ void PhaseIdealLoop::clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealL
     Unique_Node_List wq;
     for (uint i = 0; i < extra_data_nodes.size(); i++) {
       Node* old = extra_data_nodes.at(i);
-      clone_outer_loop_helper(old, loop, outer_loop, old_new, wq, this, true);
+      collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
+    }
+
+    for (uint i = 0; i < loop->_body.size(); i++) {
+      Node* old = loop->_body.at(i);
+      collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
     }
 
     Node* inner_out = sfpt->in(0);
     if (inner_out->outcnt() > 1) {
-      clone_outer_loop_helper(inner_out, loop, outer_loop, old_new, wq, this, true);
+      collect_nodes_in_outer_loop_not_reachable_from_sfpt(inner_out, loop, outer_loop, old_new, wq, this, true);
     }
 
     Node* new_ctrl = cl->outer_loop_exit();
@@ -2195,7 +2202,7 @@ void PhaseIdealLoop::clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealL
       if (n->in(0) != NULL) {
         _igvn.replace_input_of(n, 0, new_ctrl);
       }
-      clone_outer_loop_helper(n, loop, outer_loop, old_new, wq, this, false);
+      collect_nodes_in_outer_loop_not_reachable_from_sfpt(n, loop, outer_loop, old_new, wq, this, false);
     }
   } else {
     Node *newhead = old_new[loop->_head->_idx];

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

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2022, 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 8295788
+ * @summary C2 compilation hits "assert((mode == ControlAroundStripMined && use == sfpt) || !use->is_reachable_from_root()) failed: missed a node"
+ *
+ * @run main/othervm -Xcomp -XX:CompileOnly=TestUseFromInnerInOuterUnusedBySfpt TestUseFromInnerInOuterUnusedBySfpt
+ *
+ */
+
+public class TestUseFromInnerInOuterUnusedBySfpt {
+
+    public static final int N = 400;
+
+    public static void dMeth(long l, int i5, int i6) {
+
+        int i7=14, i8=-14, i9=7476, i11=0;
+        long lArr[]=new long[N];
+
+        for (i7 = 3; i7 < 177; i7++) {
+            lArr[i7 + 1] >>= l;
+            l -= i8;
+            i6 = (int)l;
+        }
+        for (i9 = 15; i9 < 356; i9 += 3) {
+            i11 = 14;
+            do {
+                i5 |= i6;
+            } while (--i11 > 0);
+        }
+    }
+
+    public static void main(String[] strArr) {
+        TestUseFromInnerInOuterUnusedBySfpt _instance = new TestUseFromInnerInOuterUnusedBySfpt();
+        for (int i = 0; i < 10; i++) {
+            _instance.dMeth(-12L, -50242, 20);
+        }
+    }
+}