2011/8/31 Terry Reedy <span dir="ltr"><<a href="mailto:tjreedy@udel.edu">tjreedy@udel.edu</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div class="im">
I find myself more comfortable with the Cesare Di Mauro's idea of expanding to 16 bits as the code unit. His basic idea was using 2, 4, or 6 bytes instead of 1, 3, or 6.</div></blockquote><div><br></div><div>It can be expanded to longer than 6 bytes opcodes, if needed. The format is designed to be flexible enough to accommodate such changes without pains.</div>
<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div class="im">It actually tended to save space because many ops with small ints (which are very common) contract from 3 bytes to 2 bytes or from 9(?) (two instructions) to 6.</div>
</blockquote><div><br></div><div>It can pack up to 4 (old) opcodes into one wordcode (superinstruction). Wordcodes are designed to favor instruction "grouping".</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div class="im">I am sorry he was not able to followup on the initial promising results.</div></blockquote><div><br></div><div>In a few words: lack of interest. Why spending (so much) time to a project when you see that the community is oriented towards other directions (Unladen Swallow at first, PyPy in the last period, given the substantial drop of the former)?</div>
<div><br></div><div>Also, Guido seems to dislike what he finds as "hacks", and never showed interest.</div><div><br></div><div>In WPython 1.1 I "rolled back" the "hack" that I introduced in PyObject types (a couple of fields) in 1.0 alpha, to make the code more "polished" (but with a sensible drop in the performance). But again, I saw no interest on WPython, so I decided to put a stop at it, and blocking my initial idea to go for Python 3. </div>
<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div class="im">The dis output was probably easier to read than the current output.<br></div>
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Perhaps he made a mistake in combining the above idea with a shift from stack to hybrid stack+register design.<br><font color="#888888">
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-- <br>
Terry Jan Reedy</font><div><div class="h5"><br>
</div></div></blockquote><div>As I already said, wordcodes are designed to favor "grouping". So It was quite natural to became an "hybrid" VM. Anyway, both space and performance gained from this wordcodes "property". ;)<br>
</div><div><br></div><div>Regards</div><div><br></div><div>Cesare</div>