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Date: Fri, 2 Feb 2007 14:08:01 +0600
From: "Aleksey Ignatenko" <aleksey.ignatenko@gmail.com>
To: dev@harmony.apache.org
Subject: Re: [DRLVM] 64-bit support with compressed pointer
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I suppose there is no easy way to do that, but one can scan all places where

#ifdef _EM64T_ appears and change appropriate places to something like
#ifdef _COMPRESSED_MODE. Plus scan such places like gc_types.h in gc_cc,
there is object header:
    VT32 vt_raw;
    unsigned info;
You need to have VT64 vt_raw;  for 64 bit mode.

p.s. In some of discussions I read that compressed mode (comparing to
uncompressed one) improved performance on about 13% on em64t.

On 2/2/07, Xiao-Feng Li <xiaofeng.li@gmail.com> wrote:

> Yes, that's exactly my question. I couldn't find an easy way to turn
> off this compressed-ptr optimization. It's a little bit surprising me.
> :-)
>
> Thanks,
> xiaofeng
>
> On 2/2/07, Aleksey Ignatenko <aleksey.ignatenko@gmail.com> wrote:
> > Did you check that it works on 64 bit mode with uncomressed references.
> > I remember some time ago there were issues like hard coded compressed
> > references used in JIT (or probably somewhere else) in 64bit mode.
> >
> > Best regards,
> > Aleksey.
> >
> > On 2/2/07, Xiao-Feng Li <xiaofeng.li@gmail.com> wrote:
> > >
> > > Hi, current 64bit support uses compressed reference pointer by
> > > default, i.e., a 64bit reference is stored as a 32bit value plus a
> > > (global) base address. This can reduce the footprint of working set
> > > and at the same time improve cache locality. But this has max heap
> > > size limitation.
> > >
> > > I wonder why not use non-compressed pointer as by default, and the
> > > compressed pointer is only an optimization that can be applied when
> > > desirable. Comments?
> > >
> > > Thanks,
> > > xiaofeng
> > >
> >
> >
>

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