From 2912349bfe24f5897d0872bb21edc5e384ae38eb Mon Sep 17 00:00:00 2001
From: d-kozak <david.kozak@oracle.com>
Date: Thu, 6 Feb 2025 16:54:38 +0100
Subject: [PATCH] prevent early constant folding of ZoneOffset.rules during
 class initializer simulation

---
 .../core/jdk/Target_java_time_ZoneOffset.java | 52 +++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jdk/Target_java_time_ZoneOffset.java

diff --git a/substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jdk/Target_java_time_ZoneOffset.java b/substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jdk/Target_java_time_ZoneOffset.java
new file mode 100644
index 000000000000..eb07925290ee
--- /dev/null
+++ b/substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jdk/Target_java_time_ZoneOffset.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2025, 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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.
+ */
+package com.oracle.svm.core.jdk;
+
+import java.time.ZoneOffset;
+import java.time.zone.ZoneRules;
+
+import com.oracle.svm.core.annotate.Alias;
+import com.oracle.svm.core.annotate.RecomputeFieldValue;
+import com.oracle.svm.core.annotate.TargetClass;
+
+@TargetClass(ZoneOffset.class)
+public final class Target_java_time_ZoneOffset {
+    /**
+     * This field is marked as @Stable, therefore we only constant fold it if it has a non-null
+     * value at the time the constant folding decision is being made.
+     * <p/>
+     * The value of this field on the image heap constant {@link ZoneOffset#UTC} gets lazily
+     * initialized at build time by calling the {@link ZoneOffset#getRules()} method. The same
+     * method is also analyzed when simulating class initializers, which can lead to
+     * non-deterministic analysis results: The success of the simulation depends on whether the
+     * method was already executed at build time. To achieve determinism, we mark this field with
+     * RecomputeFieldValue, thus preventing the constant folding during class initializer
+     * simulation.
+     */
+    @SuppressWarnings("unused") //
+    @Alias @RecomputeFieldValue(kind = RecomputeFieldValue.Kind.Reset) //
+    private ZoneRules rules;
+
+}