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From "Xiao-Feng Li" <xiaofeng...@gmail.com>
Subject Re: [DRLVM][VM] -- which header bits are available for GC mark and GC forwarding use?
Date Thu, 24 Aug 2006 04:04:51 GMT
Weldon, I experimented with last two bits for marking and forwarding
without problem.

The GC_OBJECT_MARK_BIT_MASK is for obj_info field, not the vt field. (
So far as I experimented, it's only used for heap verification).

Thanks,
xiaofeng

On 8/24/06, Weldon Washburn <weldonwjw@gmail.com> wrote:
> Looking at drlvm/trunk, it looks like vmcore/include/sync_bits.h
> defines the use of  *(ref_ptr +4) for 32-bit environment.  Just
> guessing that "#define BUSY_FORWARDING_OFFSET 0" is intended to tell
> the GC that it can use the least significant bit out of these four
> bytes.  Is this correct?  I would like to use this bit as an MMTk mark
> bit.  Will this work?  (Actually the name, BUSY_FORWARDING_OFFSET is
> probably not the best...)
>
> There is also a gc/src/gc_header.h file that contains, "#define
> GC_OBJECT_MARK_BIT_MASK 0x80".  This seems to step on top of
> sync_bits.h use of this area???    Can I assume gc_header.h is
> incorrect?
>
> --
> Weldon Washburn
> Intel Middleware Products Division
>
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