8039043: Implicit null check is in the wrong place in C1 -UseCompressedOops

Summary: Null check is placed in a wrong place when storing a null to an object field on x64 with compressed oops off
Reviewed-by: roland, vlivanov, kvn

hotspot/src/cpu/x86/vm/c1_LIRAssembler_x86.cpp

@@ -799,7 +799,13 @@ void LIR_Assembler::const2mem(LIR_Opr src, LIR_Opr dest, BasicType type, CodeEmi
         if (UseCompressedOops && !wide) {
           __ movl(as_Address(addr), (int32_t)NULL_WORD);
         } else {
+#ifdef _LP64
+          __ xorptr(rscratch1, rscratch1);
+          null_check_here = code_offset();
+          __ movptr(as_Address(addr), rscratch1);
+#else
           __ movptr(as_Address(addr), NULL_WORD);
+#endif
         }
       } else {
         if (is_literal_address(addr)) {

hotspot/test/compiler/codegen/C1NullCheckOfNullStore.java

+/*
+ * Copyright (c) 2014, 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.
+ *
+ * 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 8039043
+ * @summary Null check is placed in a wrong place when storing a null to an object field on x64 with compressed oops off
+ * @run main/othervm -Xbatch -XX:+IgnoreUnrecognizedVMOptions -XX:CompileCommand=compileonly,C1NullCheckOfNullStore::test -XX:+TieredCompilation -XX:TieredStopAtLevel=1 -XX:-UseCompressedOops C1NullCheckOfNullStore
+ *
+ */
+
+public class C1NullCheckOfNullStore {
+  private static class Foo {
+    Object bar;
+  }
+  static private void test(Foo x) {
+    x.bar = null;
+  }
+  static public void main(String args[]) {
+    Foo x = new Foo();
+    for (int i = 0; i < 10000; i++) {
+      test(x);
+    }
+    boolean gotNPE = false;
+    try {
+      for (int i = 0; i < 10000; i++) {
+        test(null);
+      }
+    }
+    catch(NullPointerException e) {
+      gotNPE = true;
+    }
+    if (!gotNPE) {
+      throw new Error("Expecting a NullPointerException");
+    }
+  }
+}