--- a/src/hotspot/share/opto/arraycopynode.cpp	Fri Jul 13 07:08:59 2018 -0700
+++ b/src/hotspot/share/opto/arraycopynode.cpp	Fri Jul 13 15:44:54 2018 +0200
@@ -366,6 +366,9 @@
   if (!forward_ctl->is_top()) {
     // copy forward
     mem = start_mem_dest;
+    uint alias_idx_src = phase->C->get_alias_index(atp_src);
+    uint alias_idx_dest = phase->C->get_alias_index(atp_dest);
+    bool same_alias = (alias_idx_src == alias_idx_dest);
 
     if (count > 0) {
       Node* v = LoadNode::make(*phase, forward_ctl, start_mem_src, adr_src, atp_src, value_type, copy_type, MemNode::unordered);
@@ -376,7 +379,7 @@
         Node* off  = phase->MakeConX(type2aelembytes(copy_type) * i);
         Node* next_src = phase->transform(new AddPNode(base_src,adr_src,off));
         Node* next_dest = phase->transform(new AddPNode(base_dest,adr_dest,off));
-        v = LoadNode::make(*phase, forward_ctl, mem, next_src, atp_src, value_type, copy_type, MemNode::unordered);
+        v = LoadNode::make(*phase, forward_ctl, same_alias ? mem : start_mem_src, next_src, atp_src, value_type, copy_type, MemNode::unordered);
         v = phase->transform(v);
         mem = StoreNode::make(*phase, forward_ctl,mem,next_dest,atp_dest,v, copy_type, MemNode::unordered);
         mem = phase->transform(mem);
@@ -408,18 +411,21 @@
   if (!backward_ctl->is_top()) {
     // copy backward
     mem = start_mem_dest;
+    uint alias_idx_src = phase->C->get_alias_index(atp_src);
+    uint alias_idx_dest = phase->C->get_alias_index(atp_dest);
+    bool same_alias = (alias_idx_src == alias_idx_dest);
 
     if (count > 0) {
       for (int i = count-1; i >= 1; i--) {
         Node* off  = phase->MakeConX(type2aelembytes(copy_type) * i);
         Node* next_src = phase->transform(new AddPNode(base_src,adr_src,off));
         Node* next_dest = phase->transform(new AddPNode(base_dest,adr_dest,off));
-        Node* v = LoadNode::make(*phase, backward_ctl, mem, next_src, atp_src, value_type, copy_type, MemNode::unordered);
+        Node* v = LoadNode::make(*phase, backward_ctl, same_alias ? mem : start_mem_src, next_src, atp_src, value_type, copy_type, MemNode::unordered);
         v = phase->transform(v);
         mem = StoreNode::make(*phase, backward_ctl,mem,next_dest,atp_dest,v, copy_type, MemNode::unordered);
         mem = phase->transform(mem);
       }
-      Node* v = LoadNode::make(*phase, backward_ctl, mem, adr_src, atp_src, value_type, copy_type, MemNode::unordered);
+      Node* v = LoadNode::make(*phase, backward_ctl, same_alias ? mem : start_mem_src, adr_src, atp_src, value_type, copy_type, MemNode::unordered);
       v = phase->transform(v);
       mem = StoreNode::make(*phase, backward_ctl, mem, adr_dest, atp_dest, v, copy_type, MemNode::unordered);
       mem = phase->transform(mem);

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/hotspot/jtreg/compiler/arraycopy/ACasLoadsStoresBadMem.java	Fri Jul 13 15:44:54 2018 +0200
@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2018, 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 8200282
+ * @summary arraycopy converted as a series of loads/stores uses wrong slice for loads
+ *
+ * @run main/othervm -XX:-TieredCompilation -XX:-BackgroundCompilation -XX:-UseOnStackReplacement -XX:CompileCommand=dontinline,ACasLoadsStoresBadMem::not_inlined  ACasLoadsStoresBadMem
+ *
+ */
+
+public class ACasLoadsStoresBadMem {
+    public static void main(String[] args) {
+        int[] dst = new int[5];
+        for (int i = 0; i < 20_000; i++) {
+            test1(dst, 1);
+            for (int j = 1; j < 5; j++) {
+                if (dst[j] != j) {
+                    throw new RuntimeException("Bad copy ");
+                }
+            }
+        }
+    }
+
+    private static void test1(int[] dst, int dstPos) {
+        int[] src = new int[4];
+        not_inlined();
+        src[0] = 1;
+        src[1] = 2;
+        src[2] = 3;
+        src[3] = 4;
+        System.arraycopy(src, 0, dst, dstPos, 4);
+    }
+
+    private static void not_inlined() {
+    }
+}