On 8/23/06, Xiao-Feng Li <[EMAIL PROTECTED]> wrote:
Weldon, I experimented with last two bits for marking and forwarding without problem.
I assume you are referring to the 2 lowest bits in the vtable pointer. The two lowest bits will step on the recursion mask in sync_bits.h... won't it? I am confused. It turns out that MMTk keeps the mark bits around even between GCs. Leaving an LSB of the vtable ptr set and then resuming application execution will surely cause a failure. Thus there needs to be a full time dedicated mark bit in the object header. This is in addition to the need for a forwarding bit.
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 <[EMAIL PROTECTED]> 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 > > --------------------------------------------------------------------- > Terms of use : http://incubator.apache.org/harmony/mailing.html > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > --------------------------------------------------------------------- Terms of use : http://incubator.apache.org/harmony/mailing.html To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
-- Weldon Washburn Intel Middleware Products Division --------------------------------------------------------------------- Terms of use : http://incubator.apache.org/harmony/mailing.html To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
