[LLVMdev] Fwd: Making a CopyToReg/CopyFromReg into a zext/sext?

[Ryan Taylor]

So you don't think it's the CopyToReg, it's the CopyFromReg potentially. If
that's the case it's still somewhat of the same issue right? I still need
an ext instead of the Copy Node.

On Tue, Jan 27, 2015 at 4:06 PM, Matt Arsenault <Matthew.Arsenault at amd.com>
wrote:

> On 01/27/2015 12:50 PM, Ryan Taylor wrote:
>
>> I have a CopyToReg that is moving a 16bit reg to a 32bit reg, it's
>> currently being mapped out as a simple mov (not an ext), I would like to
>> change that to an ext. It seemed that the SelDAG was the easiest and
>> cleanest way to do this.
>>
>> I can change the mov to an extension MI in the .td file; however, I can't
>> tell at that point whether it's a sext or a zext, so it seemed the SelDAG
>> was the better place to fix this.
>>
>>  I guess that depends on where the CopyFromReg is coming from. If you
> need an ext instruction for the copy, it sounds like the CopyFromReg that
> makes this copy is a bug in the first place.
>
> -Matt
>
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