Is it possible for BitC on CLI to satisfy the representation requirements for unions? I don't believe so, and this strikes me as an area where CLI can/should be improved.<br><br><div class="gmail_quote">On Sat, Nov 15, 2008 at 12:31 AM, Eric Northup <span dir="ltr"><<a href="mailto:digitale@digitaleric.net">digitale@digitaleric.net</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Rodrigo Kumpera wrote:<br>
> The naive approach to support generics by a CLR VM is to expand every<br>
> instantiation and produce<br>
> native code for all variations. This is far from optimal as the<br>
> generated bloat usually interacts pretty bad<br>
> with the icache.<br>
><br>
> What the VMs support [1] is sharing code for all reference types,<br>
> which expands to pretty much the same thing.<br>
> For valuetypes this sharing is non-trivial so no VM does it.<br>
The very first CLR VM to support generics actually did share code for<br>
compatible (from the perspective of the GC's reference visitor)<br>
structure types - see section 4.1 of<br>
<a href="http://research.microsoft.com/projects/clrgen/generics.pdf" target="_blank">http://research.microsoft.com/projects/clrgen/generics.pdf</a> .<br>
<br>
[...]<br>
> BTW, I think BitC would map very well on top of the CLR given it had<br>
> interface injection support.<br>
I agree that a CLI target would be interesting for BitC. No particular<br>
support for interface injection is necessary - I can imagine several<br>
direct embeddings of type classes into CLI interfaces. Polyinstantation<br>
or method dictionaries could also be done while targeting the CLI, thus<br>
treating it as a lower-level IL. The lower-level IL might potentially<br>
be compatible with the CIL subset supported by the gcc cli front-end.<br>
<br>
<br>
I didn't quite understand what Shap said about sometimes needing to<br>
dynamically fabricate a dictionary, though. Is that a consequence of<br>
separate compilation?<br>
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</blockquote></div><br>