[LLVMdev] variant generation question

[Chris Lattner]

On Fri, 9 Feb 2007, Scott Michel wrote:
> I would have expected four additional patterns, each with the (and $rC, $rA) 
> variant in it. But I only get the above four.
>
> Is this a bug or a feature? :-)

This is a feature.  They would match the same pattern, so it would just be 
generating dead code.  For the same reason, if you write something like:

(set $rd, (and $rs, 123))

you will only  get matching code for that pattern, and not for:

(set $rd, (and 123, $rs))

which is always canonicalized to the former.

-Chris

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