RFR (XS) 8241500: FieldLayout/OldLayoutCheck.java fails in 32-bit VMs

[David Holmes]

On 24/03/2020 11:19 pm, Frederic Parain wrote:
> Aleksey,
> 
> Looks good to me, thank you for fixing this.

I'm somewhat surprised that it has taken 4 weeks for this problem on 
32-bit to be noticed! :(

A comment as to why INT_OFFSET and LONG_OFFSET have those values would 
be good. Otherwise fix is fine by me too.

Thanks,
David

> Fred
> 
> 
>> On Mar 24, 2020, at 06:54, Aleksey Shipilev <shade at redhat.com> wrote:
>>
>> Test bug:
>>   https://bugs.openjdk.java.net/browse/JDK-8241500
>>
>> See the brief discussion and JOL dump in the bug.
>>
>> Fix:
>>
>> diff -r cc739b0abc44 test/hotspot/jtreg/runtime/FieldLayout/OldLayoutCheck.java
>> --- a/test/hotspot/jtreg/runtime/FieldLayout/OldLayoutCheck.java        Tue Mar 24 06:13:39 2020 +0100
>> +++ b/test/hotspot/jtreg/runtime/FieldLayout/OldLayoutCheck.java        Tue Mar 24 11:52:36 2020 +0100
>> @@ -45,28 +45,32 @@
>> import java.util.Arrays;
>> import java.util.Comparator;
>> import jdk.internal.misc.Unsafe;
>>
>> import jdk.test.lib.Asserts;
>> +import jdk.test.lib.Platform;
>>
>> public class OldLayoutCheck {
>>
>>      static class LIClass {
>>          public long l;
>>          public int i;
>>      }
>>
>> +    static final long INT_OFFSET  = Platform.is64bit() ? 12L : 16L;
>> +    static final long LONG_OFFSET = Platform.is64bit() ? 16L :  8L;
>> +
>>      static public void main(String[] args) {
>>          Unsafe unsafe = Unsafe.getUnsafe();
>>          Class c = LIClass.class;
>>          Field[] fields = c.getFields();
>>          for (int i = 0; i < fields.length; i++) {
>>              long offset = unsafe.objectFieldOffset(fields[i]);
>>              if (fields[i].getType() == int.class) {
>> -                Asserts.assertEquals(offset, 12L, "Misplaced int field");
>> +                Asserts.assertEquals(offset, INT_OFFSET, "Misplaced int field");
>>              } else if (fields[i].getType() == long.class) {
>> -                Asserts.assertEquals(offset, 16L, "Misplaced long field");
>> +                Asserts.assertEquals(offset, LONG_OFFSET, "Misplaced long field");
>>              } else {
>>                  Asserts.fail("Unexpected field type");
>>              }
>>          }
>>      }
>>
>> Testing: affected test on Linux {x86_64, x86_32}
>>
>> -- 
>> Thanks,
>> -Aleksey
>>
>