[LLVMdev] Metadata

[Chris Lattner]

On Feb 10, 2010, at 9:27 AM, Devang Patel wrote:

> On Wed, Feb 10, 2010 at 12:02 AM, David Greene <dag at cray.com> wrote:
>> Since 2.7 is getting close to code freeze, I'd like to see if I can get in our
>> changes to track non-temporal memory operations into trunk.
>> 
>> As discussed earlier, I was hoping to do this via metadata.  It's pretty clear
>> how to attach the data to Instructions, but after that, I'm not sure what
>> happens.  Somehow we have to carry this all the way back into MachineInstrs.
>> 
>> What happens to metadata when SelectionDAGs get built?  Is it lost?
> 
> It is still there.
> 
>> Is there any mechanism to attach metadata to SDNodes or MachineInstrs?
> 
> There is not any mechanism to attach metadata with SDNode or
> MachineInstrs today.

For nontemporal stores, you wouldn't want to do this anyway.  In selectiondag builder, you'd want to check the store instruction to see if it has the metadata on it, and if so make a different ISD opcode or something.

-Chris