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From "Pavel Pervov" <pmcfi...@gmail.com>
Subject Re: [DRLVM] what's the purpose to set NEXT_TO_HIGH_BIT_SET_MASK in object size?
Date Wed, 21 Mar 2007 15:04:59 GMT
"is now implemented" it was supposed to be written. :)

On 3/21/07, Pavel Pervov <pmcfirst@gmail.com> wrote:
>
> It is indirectly used in the NSO for Class.newInstance. But this code is
> not currently executed, since Class.newInstance is not implemented in
> Java.
>
> WBR,
>     Pavel.
> On 3/21/07, Xiao-Feng Li <xiaofeng.li@gmail.com> wrote:
>
> > Pavel, Thanks for your reply.
> >
> > Would let me know how NEXT_TO_HIGH_BIT is used currently in DRLVM? Or
> > in other words, what functionalities are dependent on
> > NEXT_TO_HIGH_BIT?
> >
> > Thanks,
> > xiaofeng
> >
> > On 3/21/07, Pavel Pervov <pmcfirst@gmail.com> wrote:
> > > Xiao-Feng,
> > >
> > > All the infructructure is in place. It is just do not work at the
> > moment.
> > > As Class.newInstance is not native, NSO does not replace it's
> > implementation
> > > with VM's stub.
> > > If NEXT_TO_HIGH_BIT-supporting code is to be removed, the rest of the
> > code
> > > (NSO implementations for ia32 and ia64) has to be removed altogether
> > to not
> > > provoke any errors in the future.
> > >
> > > Does removing NSO overrides for Class.newInstance look reasonable for
> > you?
> > >
> > > WBR,
> > >     Pavel.
> > >
> > > On 3/21/07, Xiao-Feng Li <xiaofeng.li@gmail.com> wrote:
> > > >
> > > > If no one objects, I will try to remove this flag in DRLVM.
> > > >
> > > > Thanks,
> > > > xiaofeng
> > > >
> > > > On 3/21/07, Xiao-Feng Li <xiaofeng.li@gmail.com> wrote:
> > > > > Hi, the source code for class preparation calls
> > > > > set_instance_data_size_constraint_bit() for three situations:
> > special
> > > > > alignment requirement, having finalizer, and to be pinned. And the
> > > > > comments there say the constraint bit is for GC to understand.
> > > > >
> > > > > But current GC actually doesn't care about this bit, and simply
> > masks
> > > > > it off. Does anybody know what are the situations for the size
> > > > > constraint bit to be set for allocation?
> > > > >
> > > > > I recall this kind of constraint bit was ORP legacy, when the
> > > > > intention was for gc_alloc_fast to be really fast, avoiding any
> > > > > special allocation treatment. So once the big flag is set,
> > > > > gc_alloc_fast will simply return NULL, and the VM will invoke
> > gc_alloc
> > > > > to accomplish the allocation.
> > > > >
> > > > > Now DRLVM has different processing, and the GC doesn't use the
> > flag in
> > > > > size for allocation. I wonder what is the real purpose of this
> > size
> > > > > flag in allocation.
> > > > >
> > > > > Thanks,
> > > > > xiaofeng
> > > > >
> > > >
> > >
> > >
> > >
> > > --
> > > Pavel Pervov,
> > > Intel Enterprise Solutions Software Division
> > >
> >
>
>
>
> --
> Pavel Pervov,
> Intel Enterprise Solutions Software Division
>



-- 
Pavel Pervov,
Intel Enterprise Solutions Software Division

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