From ed4cd2acd2d8bb92c296c5a860c76cffaff53add Mon Sep 17 00:00:00 2001
From: Roland Westrelin <roland@openjdk.org>
Date: Mon, 26 May 2025 08:33:37 +0000
Subject: [PATCH] 8356989: Unexpected null in C2 compiled code

Reviewed-by: chagedorn, kvn, thartmann
---
 src/hotspot/share/opto/escape.cpp             | 12 ++--
 ...SameSrcDstInitializesNonEscapingArray.java | 60 +++++++++++++++++++
 2 files changed, 64 insertions(+), 8 deletions(-)
 create mode 100644 test/hotspot/jtreg/compiler/escapeAnalysis/TestArrayCopySameSrcDstInitializesNonEscapingArray.java

diff --git a/src/hotspot/share/opto/escape.cpp b/src/hotspot/share/opto/escape.cpp
index 3a6a81f656e..3dd43f12b2f 100644
--- a/src/hotspot/share/opto/escape.cpp
+++ b/src/hotspot/share/opto/escape.cpp
@@ -2260,14 +2260,10 @@ void ConnectionGraph::process_call_arguments(CallNode *call) {
             }
             PointsToNode* src_ptn = ptnode_adr(src->_idx);
             assert(src_ptn != nullptr, "should be registered");
-            if (arg_ptn != src_ptn) {
-              // Special arraycopy edge:
-              // A destination object's field can't have the source object
-              // as base since objects escape states are not related.
-              // Only escape state of destination object's fields affects
-              // escape state of fields in source object.
-              add_arraycopy(call, es, src_ptn, arg_ptn);
-            }
+            // Special arraycopy edge:
+            // Only escape state of destination object's fields affects
+            // escape state of fields in source object.
+            add_arraycopy(call, es, src_ptn, arg_ptn);
           }
         }
       }
diff --git a/test/hotspot/jtreg/compiler/escapeAnalysis/TestArrayCopySameSrcDstInitializesNonEscapingArray.java b/test/hotspot/jtreg/compiler/escapeAnalysis/TestArrayCopySameSrcDstInitializesNonEscapingArray.java
new file mode 100644
index 00000000000..ffc44266c1d
--- /dev/null
+++ b/test/hotspot/jtreg/compiler/escapeAnalysis/TestArrayCopySameSrcDstInitializesNonEscapingArray.java
@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2025, 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 8356989
+ * @summary Unexpected null in C2 compiled code
+ * @run main/othervm -XX:-BackgroundCompilation TestArrayCopySameSrcDstInitializesNonEscapingArray
+ * @run main TestArrayCopySameSrcDstInitializesNonEscapingArray
+ */
+
+ public class TestArrayCopySameSrcDstInitializesNonEscapingArray {
+    private static volatile int volatileField;
+
+    public static void main(String[] args) {
+        Object obj = new Object();
+        for (int i = 0; i < 20_000; i++) {
+            test1(obj);
+        }
+    }
+
+    private static void test1(Object obj) {
+        A a = new A();
+        Object[] array = new Object[2];
+        array[0] = obj;
+        a.field = array;
+        System.arraycopy(array, 0, array, 1, 1);
+        if (a.field[1] == null) {
+            throw new RuntimeException("Can't be null");
+        }
+    }
+
+    private static class A {
+        Object[] field;
+
+        public A() {
+            field = null;
+        }
+    }
+}