8220714: C2 Compilation failure when accessing off-heap memory using Unsafe

Reviewed-by: vlivanov, roland

src/hotspot/share/opto/library_call.cpp

@@ -2407,7 +2407,7 @@ bool LibraryCallKit::inline_unsafe_access(bool is_store, const BasicType type, c
   }
 
   // Can base be NULL? Otherwise, always on-heap access.
-  bool can_access_non_heap = TypePtr::NULL_PTR->higher_equal(_gvn.type(heap_base_oop));
+  bool can_access_non_heap = TypePtr::NULL_PTR->higher_equal(_gvn.type(base));
 
   if (!can_access_non_heap) {
     decorators |= IN_HEAP;

test/hotspot/jtreg/gc/shenandoah/compiler/TestUnsafeOffheapSwap.java

@@ -0,0 +1,109 @@
+/*
+ * Copyright (c) 2019, 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 TestUnsafeOffheapSwap
+ * @summary Miscompilation in Unsafe off-heap swap routines
+ * @key gc
+ * @requires vm.gc.Shenandoah
+ * @modules java.base/jdk.internal.misc:+open
+ *
+ * @run main/othervm -XX:-UseOnStackReplacement -XX:-BackgroundCompilation -XX:-TieredCompilation
+ *                   -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC
+ *                   TestUnsafeOffheapSwap
+ */
+
+import java.util.*;
+import jdk.internal.misc.Unsafe;
+
+public class TestUnsafeOffheapSwap {
+
+    static final int SIZE = 10000;
+    static final long SEED = 1;
+
+    static final jdk.internal.misc.Unsafe UNSAFE = Unsafe.getUnsafe();
+    static final int SCALE = UNSAFE.ARRAY_INT_INDEX_SCALE;
+
+    static Memory mem;
+    static int[] arr;
+
+    public static void main(String[] args) throws Exception {
+        // Bug is exposed when memory.addr is not known statically
+        mem = new Memory(SIZE*SCALE);
+        arr = new int[SIZE];
+
+        for (int i = 0; i < 10; i++) {
+            test();
+        }
+    }
+
+    static void test() {
+        Random rnd = new Random(SEED);
+        for (int i = 0; i < SIZE; i++) {
+            int value = rnd.nextInt();
+            mem.setInt(i, value);
+            arr[i] = value;
+        }
+
+        for (int i = 0; i < SIZE; i++) {
+            if (arr[i] != mem.getInt(i)) {
+                throw new IllegalStateException("TESTBUG: Values mismatch before swaps");
+            }
+        }
+
+        for (int i = 1; i < SIZE; i++) {
+            mem.swap(i - 1, i);
+            int tmp = arr[i - 1];
+            arr[i - 1] = arr[i];
+            arr[i] = tmp;
+        }
+
+        for (int i = 0; i < SIZE; i++) {
+            if (arr[i] != mem.getInt(i)) {
+                throw new IllegalStateException("Values mismatch after swaps");
+            }
+        }
+    }
+
+    static class Memory {
+        private final long addr;
+
+        Memory(int size) {
+            addr = UNSAFE.allocateMemory(size);
+        }
+
+        public int getInt(int idx) {
+            return UNSAFE.getInt(addr + idx*SCALE);
+        }
+
+        public void setInt(int idx, int val) {
+            UNSAFE.putInt(addr + idx*SCALE, val);
+        }
+
+        public void swap(int a, int b) {
+            int tmp = getInt(a);
+            setInt(a, getInt(b));
+            setInt(b, tmp);
+        }
+    }
+}