8361117: SIGSEGV in LShiftLNode::Ideal due to unexpected dead node

Reviewed-by: roland

Author: TheRealMDoerr

src/hotspot/share/opto/arraycopynode.cpp

@@ -307,7 +307,13 @@ bool ArrayCopyNode::prepare_array_copy(PhaseGVN *phase, bool can_reshape,
       return false;
     }
 
+    Node* hook = new Node(1);
+    hook->init_req(0, dest_offset);
+
     Node* src_scale  = phase->transform(new LShiftXNode(src_offset, phase->intcon(shift)));
+
+    hook->destruct(phase);
+
     Node* dest_scale = phase->transform(new LShiftXNode(dest_offset, phase->intcon(shift)));
 
     adr_src          = phase->transform(new AddPNode(base_src, base_src, src_scale));

test/hotspot/jtreg/compiler/c2/TestArrayCopyLShiftIdealization.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2025 SAP SE. 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 8361117
+ * @summary SIGSEGV in LShiftLNode::Ideal due to unexpected dead node
+ *
+ * @run main/othervm -XX:-TieredCompilation
+ *      -XX:CompileCommand=compileonly,compiler.c2.TestArrayCopyLShiftIdealization::test
+ *      compiler.c2.TestArrayCopyLShiftIdealization
+ */
+
+package compiler.c2;
+
+public class TestArrayCopyLShiftIdealization {
+    public static void test() {
+        int size = 1000;
+        int[] arr1 = new int[size];
+        int[] arr2 = new int[size];
+        for (int i = 0; i < size; i++) {
+            arr1[i] = i;
+        }
+        for (int i = 0; i < size; i += 10) {
+            for (int j = 0; j < 5; j++) {
+                int srcPos = i + j;
+                int destPos = i + j;
+                int length = 5 - j;
+                java.lang.System.arraycopy(arr1, srcPos, arr2, destPos,
+                        length);
+            }
+        }
+    }
+
+    public static void main(String[] args) {
+        for (int i = 0; i < 10_000; i++) {
+            test();
+        }
+    }
+}