<br><br><div class="gmail_quote">On Wed, Mar 7, 2012 at 1:57 AM, Stefan Marr <span dir="ltr"><<a href="mailto:smalltalk@stefan-marr.de">smalltalk@stefan-marr.de</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
Hi Eliot:<br>
<div class="im"><br>
On 07 Mar 2012, at 01:47, Eliot Miranda wrote:<br>
<br>
> But the flag is really useful for VM/image communication.<br>
</div>Right, that's what I want to use it for.<br>
Flagged methods will allow me to mark exit points from a special interpretation mode.<br>
In that special mode, I enforce certain additional semantics, but need to be able to disable that to get back to the normal mode.<br>
The flag seems to be a convenient way to do that.<br>
<div class="im"><br>
<br>
> This is related to the above. I've just added support to Squeak trunk for accessing the sign bit in the method header and using this as an additional flag.<br>
<br>
</div>Ehm, I am not completely with you. I think, I misunderstand something here, which header word exactly?<br>
<br>
I looked through the diff of VMMaker.oscog-eem.146 and see this line:<br>
^(objectMemory integerValueOf: (self headerOf: aMethodObj)) < 0<br>
<br>
Isn't that the mark bit for the GC? Or am I confusing something?<br></blockquote><div><br></div><div>Yes, you're confusing the object header with the method header, which is unsurprising. herderOf: should really be called methodHeaderOf: but isn't (again history). So this is the sign bit in the method header (a SmallInteger) and is the bit next to the flag bit.</div>
<div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
#headerOf: should be the first word of every object, right?<br></blockquote><div><br></div><div>You'd think, but no :)</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
And at least in the RoarVM (I doubt that this is different from the standard interpreter), MarkBit is defined as (1 << 31), isn't that exactly the sign bit?<br></blockquote><div><br></div><div>Purely coincidental ;)</div>
<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
Thanks<br>
<font color="#888888">Stefan<br>
</font><div><div></div><div class="h5"><br>
<br>
--<br>
Stefan Marr<br>
Software Languages Lab<br>
Vrije Universiteit Brussel<br>
Pleinlaan 2 / B-1050 Brussels / Belgium<br>
<a href="http://soft.vub.ac.be/~smarr" target="_blank">http://soft.vub.ac.be/~smarr</a><br>
Phone: <a href="tel:%2B32%202%20629%202974" value="+3226292974">+32 2 629 2974</a><br>
Fax: <a href="tel:%2B32%202%20629%203525" value="+3226293525">+32 2 629 3525</a><br></div></div></blockquote></div>-- <br>best,<div>Eliot</div><br>