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From Salikh Zakirov <Salikh.Zaki...@Intel.com>
Subject Re: [Fwd: Re: [DRLVM][JET] write barrier for Java (mmtk)]
Date Fri, 13 Oct 2006 11:58:42 GMT

Weldon Washburn wrote:
>> I actually stumbled on this bug during bringup.  I replaced
>> ...plus(arrayOffset)... with ...plus(12)...  Its a hack.  But now it
>> looks
>> like I simply set ARRAY_BASE_OFFSET to 12 during <clinit>.  Does this
>> seem
>> right??

By the way, the array base offset may differ depending on the platform and array type.
As as I know, currently on 32 bit platform (ia32) the array base offset
is 12 for types of size <= 4.
Double[] and long[] arrays have array base offset 16.

on 64 bit platforms, if the vtable pointers are compressed (they are now),
the array base offset is the same as on 32 bit platforms.

Should someone disable vtable reference compression, the array base offset
will be always 16 (8 bytes vptr + 4 bytes flags + 4 bytes array size).


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