[cfe-dev] improved vector bool/pixel support

Douglas Gregor dgregor at apple.com
Tue Jul 6 13:46:33 PDT 2010

On Jul 6, 2010, at 1:36 PM, Chris Lattner wrote:

> On Jul 6, 2010, at 10:37 AM, Douglas Gregor wrote:
>>> Eliminated changes to the canonical type, added compatibility checking instead - patch is attached. Verified changed tests and ensured that patch have not affected common test results.
>> Oops, I missed Chris's original request for me to look at this. Anyway, I disagree with Chris: if the AltiVec vector types are meant to be identical to GNU vector types, then they need to have the same canonical type. The code that is currently in the tree looks like it does that properly already.
> I'm happy to defer to Doug's opinion here.  However, I thought that the idea of a canonical type was that it represent the structural behavior of the type.  Semantically there should be no difference between the sugared and desugared type.  If "altivec" vectors have more behavior than just how they print, I don't think it's just sugar, right?

Do AltiVec vectors have more/different behavior from than GCC vectors? I honestly don't know. If they do, they need their own canonical types and we'll need to introduce appropriate implicit conversions between the two kinds of vectors. If the behavior is the same, then it's just sugar.

	- Doug

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