From 4ad5d5514e8fccc17f7be900e008e83f09e34e97 Mon Sep 17 00:00:00 2001
From: Theo Weidmann <tweidmann@openjdk.org>
Date: Thu, 16 Jan 2025 12:16:14 +0000
Subject: [PATCH] 8325030: PhaseMacroExpand::value_from_mem_phi assert with
 "unknown node on this path"

Reviewed-by: chagedorn, kvn
---
 src/hotspot/share/opto/macro.cpp              |  6 +-
 .../macronodes/TestTopInMacroElimination.java | 55 +++++++++++++++++++
 2 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 test/hotspot/jtreg/compiler/macronodes/TestTopInMacroElimination.java

diff --git a/src/hotspot/share/opto/macro.cpp b/src/hotspot/share/opto/macro.cpp
index 289ea30a633..3ddab602c77 100644
--- a/src/hotspot/share/opto/macro.cpp
+++ b/src/hotspot/share/opto/macro.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2005, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2025, 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
@@ -430,6 +430,10 @@ Node *PhaseMacroExpand::value_from_mem_phi(Node *mem, BasicType ft, const Type *
           return nullptr;
         }
         values.at_put(j, res);
+      } else if (val->is_top()) {
+        // This indicates that this path into the phi is dead. Top will eventually also propagate into the Region.
+        // IGVN will clean this up later.
+        values.at_put(j, val);
       } else {
         DEBUG_ONLY( val->dump(); )
         assert(false, "unknown node on this path");
diff --git a/test/hotspot/jtreg/compiler/macronodes/TestTopInMacroElimination.java b/test/hotspot/jtreg/compiler/macronodes/TestTopInMacroElimination.java
new file mode 100644
index 00000000000..86ff4e9b874
--- /dev/null
+++ b/test/hotspot/jtreg/compiler/macronodes/TestTopInMacroElimination.java
@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2025, 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 8325030
+ * @summary Regression test for an assert triggered during allocation elimination because top is found during
+ * constructing new phis.
+ * @run main/othervm -XX:-ProfileExceptionHandlers compiler.macronodes.TestTopInMacroElimination
+ */
+
+package compiler.macronodes;
+
+public class TestTopInMacroElimination {
+    public static class A {
+        int a;
+    }
+
+    public static void main(String[] strArr) {
+        int i2 = 0;
+        for (int i = 0; i < 50; ++i) {
+            try {
+                synchronized (new A()) {
+                    synchronized (TestTopInMacroElimination.class) {
+                        for (int var19 = 0; var19 < Integer.valueOf(i2);) {
+                            Integer.valueOf(var19);
+                        }
+                    }
+                }
+                for (int var8 = 0; var8 < 10000; ++var8) ;
+            } catch (ArithmeticException a_e) {
+            }
+        }
+    }
+}