8294217: Assertion failure: parsing found no loops but there are some

src/hotspot/share/opto/loopnode.cpp

@@ -3693,24 +3693,45 @@ bool PhaseIdealLoop::process_expensive_nodes() {
 }
 
 #ifdef ASSERT
+// Goes over all children of the root of the loop tree, collects all controls for the loop and its inner loops then
+// checks whether any control is a branch out of the loop and if it is, whether it's not a NeverBranch.
 bool PhaseIdealLoop::only_has_infinite_loops() {
   for (IdealLoopTree* l = _ltree_root->_child; l != NULL; l = l->_next) {
-    uint i = 1;
-    for (; i < C->root()->req(); i++) {
-      Node* in = C->root()->in(i);
-      if (in != NULL &&
-          in->Opcode() == Op_Halt &&
-          in->in(0)->is_Proj() &&
-          in->in(0)->in(0)->Opcode() == Op_NeverBranch &&
-          in->in(0)->in(0)->in(0) == l->_head) {
-        break;
+    Unique_Node_List wq;
+    Node* head = l->_head;
+    assert(head->is_Region(), "");
+    for (uint i = 1; i < head->req(); ++i) {
+      Node* in = head->in(i);
+      if (get_loop(in) != _ltree_root) {
+        wq.push(in);
       }
     }
-    if (i == C->root()->req()) {
-      return false;
+    for (uint i = 0; i < wq.size(); ++i) {
+      Node* c = wq.at(i);
+      if (c == head) {
+        continue;
+      } else if (c->is_Region()) {
+        for (uint j = 1; j < c->req(); ++j) {
+          wq.push(c->in(j));
+        }
+      } else {
+        wq.push(c->in(0));
+      }
+    }
+    assert(wq.member(head), "");
+    for (uint i = 0; i < wq.size(); ++i) {
+      Node* c = wq.at(i);
+      if (c->is_MultiBranch()) {
+        for (DUIterator_Fast jmax, j = c->fast_outs(jmax); j < jmax; j++) {
+          Node* u = c->fast_out(j);
+          assert(u->is_CFG(), "");
+          if (!wq.member(u) && c->Opcode() != Op_NeverBranch) {
+            return false;
+          }
+        }
+      }
     }
   }
-
   return true;
 }
 #endif
@@ -3725,6 +3746,8 @@ void PhaseIdealLoop::build_and_optimize() {
 
   bool do_split_ifs = (_mode == LoopOptsDefault);
   bool skip_loop_opts = (_mode == LoopOptsNone);
+  bool do_max_unroll = (_mode == LoopOptsMaxUnroll);
+
 
   int old_progress = C->major_progress();
   uint orig_worklist_size = _igvn._worklist.size();
@@ -3794,8 +3817,8 @@ void PhaseIdealLoop::build_and_optimize() {
 
   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
   // Nothing to do, so get out
-  bool stop_early = !C->has_loops() && !skip_loop_opts && !do_split_ifs && !_verify_me && !_verify_only &&
-    !bs->is_gc_specific_loop_opts_pass(_mode);
+  bool stop_early = !C->has_loops() && !skip_loop_opts && !do_split_ifs && !do_max_unroll && !_verify_me &&
+          !_verify_only && !bs->is_gc_specific_loop_opts_pass(_mode);
   bool do_expensive_nodes = C->should_optimize_expensive_nodes(_igvn);
   bool strip_mined_loops_expanded = bs->strip_mined_loops_expanded(_mode);
   if (stop_early && !do_expensive_nodes) {
@@ -3934,7 +3957,7 @@ void PhaseIdealLoop::build_and_optimize() {
     return;
   }
 
-  if (_mode == LoopOptsMaxUnroll) {
+  if (do_max_unroll) {
     for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
       IdealLoopTree* lpt = iter.current();
       if (lpt->is_innermost() && lpt->_allow_optimizations && !lpt->_has_call && lpt->is_counted()) {

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

@@ -0,0 +1,72 @@
+/*
+ * 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 8294217
+ * @summary Assertion failure: parsing found no loops but there are some
+ * @library /test/lib
+ *
+ * @run main/othervm -Xmx1G -XX:-BackgroundCompilation TestInfiniteLoopNest
+ *
+ */
+
+import jdk.test.lib.Utils;
+
+public class TestInfiniteLoopNest {
+    long l;
+
+    void q() {
+        if (b) {
+            Object o = new Object();
+            return;
+        }
+
+        do {
+            l++;
+            while (l != 1) --l;
+            l = 9;
+        } while (l != 5);
+
+    }
+
+    public static void main(String[] p) throws Exception {
+        Thread thread = new Thread() {
+            public void run() {
+                TestInfiniteLoopNest t = new TestInfiniteLoopNest();
+                for (int i = 524; i < 19710; i += 1) {
+                    b = true;
+                    t.q();
+                    b = false;
+                }
+                t.q();
+            }
+        };
+        // Give thread some time to trigger compilation
+        thread.setDaemon(true);
+        thread.start();
+        Thread.sleep(Utils.adjustTimeout(4000));
+    }
+
+    static Boolean b;
+}