Image format proposals... Re: [SqF]Report of VI4 Project for Feb '02

Hannes Hirzel hirzel at spw.unizh.ch
Sun Feb 3 11:09:19 UTC 2002


Just curious: Could somebody give me a pointer to the object header format
actually currently?

Hannes Hirzel


On Sun, 3 Feb 2002, Scott A Crosby wrote:

> On Sun, 3 Feb 2002, Scott A Crosby wrote:
> 
> > On Sun, 3 Feb 2002, Hans-Martin Mosner wrote:
> >
> > --
> > Switch to 128/64-bit headers?
> >
> > -- 64 bits
> > 18 length (all zero's indicate long header)
> >  2 object type
> >      00 - Object contains no references
> >      01 - Object is a forwarding pointer.
> >      10 - (long header) 4th word in header is an oop to be checked in GC
> >      11 - Object weakly references other objects.
> >  4 for reserved for GC.
> >  8 unused. (for immutible, special behavior, etc) [*]
> >
> > 16 hashbits
> > 16 class# (looked up on a seperate table)
> > --
> 
> Rereading, its wrong, but you get the idea of the brainstorm.
> 
> There needs to be a combination in the object type that signifies that its
> a normal object.
> 
> Scott
> 
> 
> 
> 




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