8273115: CountedLoopEndNode::stride_con crash in debug build with -XX…

…:+TraceLoopOpts

Backport-of: dc6358444b34a4861758a6b41aeebbe737345106

src/hotspot/share/opto/loopTransform.cpp

@@ -2156,6 +2156,20 @@ void PhaseIdealLoop::do_unroll(IdealLoopTree *loop, Node_List &old_new, bool adj
         new_limit = new CMoveINode(adj_bool, adj_limit, adj_max, TypeInt::INT);
       }
       register_new_node(new_limit, ctrl);
+      if (loop_head->unrolled_count() == 1) {
+        // The Opaque2 node created above (in the case of the first unrolling) hides the type of the loop limit.
+        // As a result, if the iv Phi constant folds (because it captured the iteration range), the exit test won't
+        // constant fold and the graph contains a broken counted loop.
+        const Type* new_limit_t;
+        if (stride_con > 0) {
+          new_limit_t = TypeInt::make(min_jint, limit_type->_hi, limit_type->_widen);
+        } else {
+          assert(stride_con < 0, "stride can't be 0");
+          new_limit_t = TypeInt::make(limit_type->_lo, max_jint, limit_type->_widen);
+        }
+        new_limit = new CastIINode(new_limit, new_limit_t);
+        register_new_node(new_limit, ctrl);
+      }
     }
 
     assert(new_limit != NULL, "");

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

@@ -0,0 +1,50 @@
+/*
+ * 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 8273115
+ * @summary CountedLoopEndNode::stride_con crash in debug build with -XX:+TraceLoopOpts
+ * @run main/othervm -XX:+IgnoreUnrecognizedVMOptions -XX:+TraceLoopOpts -Xcomp -XX:-TieredCompilation
+ *                   -XX:CompileOnly=TestBadlyFormedCountedLoop.main TestBadlyFormedCountedLoop
+ */
+
+public class TestBadlyFormedCountedLoop {
+    static int y;
+    static int[] A = new int[1];
+
+    public static void main(String[] args) {
+        for (int i = 0; i < 10; i+=2) {
+            int k;
+            int j;
+            for (j = 1; (j += 3) < 5; ) {
+                A[0] = 0;
+                for (k = j; k < 5; k++) {
+                    y++;
+                }
+            }
+            y = j;
+        }
+    }
+
+}